Article

ISSN 0006-2979, Biochemistry (Moscow), 2025, Vol. 90, Suppl. 2, pp. S403-S431 © Pleiades Publishing, Ltd., 2025.

S403

REVIEW

The Discovery of Magnetic Resonance

in the Context of 20th Century Science:

Biographies and Bibliography.

I: Discoverers of Magnetic Resonance in Matter

Alexander V. Kessenikh

and Vasily V. Ptushenko

2,3,a

Vavilov Institute for the History of Science and Technology, Russian Academy of Sciences,

125315 Moscow, Russia

Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University,

119992 Moscow, Russia

Emanuel Institute of Biochemical Physics, Russian Academy of Sciences,

119334 Moscow, Russia

e-mail: ptush@belozersky.msu.ru

Received December 24, 2025

Revised December 24, 2025

Accepted December 30, 2025

Abstract— This article is a translation of the first chapter from the book “The Discovery of Magnetic Reso-

nance in the Context of 20th Century Science: Biographies and Bibliography”. The book, dedicated to the 75th

anniversary of magnetic resonance discovery, chronicles the history and bibliography of this major break-

through in the 20th century physics (in Russian). In it, biographical accounts of E.  K.  Zavoisky, E.  M.  Purcell,

and F.  Bloch, outstanding physicists and fathers of magnetic resonance methods, are given. For each, a path to

this discovery and works beyond it are described. Research preceding the discovery of the electron spin res-

onance and nuclear magnetic resonance as well as the first works in this new field of science are discussed.

DOI: 10.1134/S0006297925604459

Keywords: electron paramagnetic (spin) resonance (EPR/ESR), nuclear magnetic resonance (NMR), Gorter, Rabi,

Zavoisky, Purcell, Bloch

# Deceased.

* To whom correspondence should be addressed.

EVGENY K. ZAVOISKY (1907-1976) –

DISCOVERER OF EPR

Evgeny Konstantinovich Zavoisky, author of one

of the most dramatic discoveries of the 20th cen-

tury physics, paradoxically, is little known in his

country. His recognition is far exceeded by that of

Kapitsa, Landau, Semenov, Kurchatov, Artsimovich,

Kikoin, Skobeltsyn, or other Soviet physicists working

roughly at the same time; his unorthodox thinking,

ever-pushing the boundaries of accepted perception,

most likely, being the reason. He never belonged to

any of the prominent scientific schools. After he had

become the member of the Academy of Sciences of

the Soviet Union, he continued to perform his ex-

periments with his own hands. Zavoisky saw himself

first and foremost as a scientist, not as a “science

manager” (the latter was typical for the members of

the Academy). His aspirations were directed to the

advancement of Soviet science rather than to the

advancement of his personal scientific career. “Ser-

vant of the state” by his position at the Academy,

he nevertheless refused to sign the open letter de-

nouncing dissident Andrey Sakharov, unlike many of

his fellow academicians. By no means was electron

paramagnetic resonance his only contribution to sci-

ence, although a stellar one, worthy of a Nobel Prize.

He was the father of a whole new field of applied

physics – picosecond electron-optical chronography –

and thus made it possible for the researchers in plas-

ma physics, nuclear physics, laser physics, astronomy,

KESSENIKH, PTUSHENKOS404

BIOCHEMISTRY (Moscow) Vol. 90 Suppl. 2 2025

Fig.  1. E.  K.  Zavoisky. Source: N.  E.  Zavoiskaya’s personal

archive.

and biology to investigate ultrafast processes. He was

the man behind the advent of polarized nuclei sourc-

es for accelerators. As well he was the man behind

one of the greatest discoveries in plasma physics –

that of turbulent heating. His biography eloquently

shows all of his breakthrough accomplishments com-

ing along in spite of the trying circumstances of his

life and work (see Fig. 1).

Evgeny Zavoisky was born in Mohyliv-on-Dni-

ester, Ukraine, the Russian Empire, to a family of

an army doctor, Konstantin Ivanovich, and his wife

Yelizaveta Nikolaevna Zavoiskys [1]

. The family name

has toponymic origins and means, literally, the per-

son who lives behind the river Voya (a tributary of

the river Vyatka in European Russia, to the west of

the Urals). The name came from a direct ancestor

of the family, a clergyman, who settled down at the

river Voya early in the 19th century – it was custom-

ary at the time in rural Russia to call new settlers

by the name of the place they settled down nearby,

rather than by their original family names. Grandfa-

ther of Zavoisky was the first in the family to leave

clergy for the secular employment, his new position

demanded a good deal of traveling. His son, Kon-

stantin, farther to Evgeny Konstantinovich, was born

in Malmyzh, Vyatka Gubernia (Province). Konstantin

Zavoisky graduated from the Military Medical Acade-

my in Saint Petersburg and served as an army doctor

in the Far East, Russia, for several years before and

during the Russo-Japanese War. In 1908, the family

moved to Kazan, where Konstantin Zavoisky obtained

an appointment as a doctor at the powder mill.

There were five children in the family, two

daughters and three sons, of which Evgeny Konstan-

tinovich was the third child. When the First World

War broke out, his father was posted to a field hos-

pital. Then the Russian Revolution of 1917 broke out,

and life took a sharp turn for the worse. Konstantin

Zavoisky died of a severe illness. In 1921, the family

had to relocate back to Vyatka Gubernia to live with

the sister of their late farther – she had a kitchen

garden, a circumstance that provided the family with

a better chance to survive. There, young Zenya

was

sent to elementary school and first discovered his in-

terest in amateur radio. The provincial capital, Kazan

was far better suited for the children to finish their

education, so five years later, in 1925, the family re-

turned back to the capital city.

A gifted young man, Evgeny finished secondary

school in 1926, and passed brilliantly entrance ex-

aminations for the Kazan State University to study

mathematics and physics with his family difficult fi-

nancial situation never stopping him from pursuing

his passion for knowledge. He had to take odd jobs,

had a lot of household chores to perform, had only

his father hand-me-downs to wear, and yet, every day

he was walking a long way to get to the University.

Undoubted talent of the freshman student was rec-

ognized immediately by his professors, among which

there were renowned scientists teaching at the Uni-

versity at the time. Evgeny started experimental work

at the laboratory early on in his University years, and

was, by all accounts, an inquisitive student reading

far above and beyond his curriculum.

One of the key influences on his scientific

explorations was Professor Vsevolod Alexandrovich

Ulyanin (1863-1931) (Fig.  2), an outstanding experi-

mental physicist. The little that is known about the

life and work of Vsevolod Ulyanin was researched and

published by Zavoisky’s daughter, Natalya Zavoiskaya

[2]. Ulyanin was brilliantly educated. He studied

mathematics and physics at the Imperial University

of Dorpat, the Russian Empire (present day Univer-

sity of Tartu, Estonia), the University of Munich, and

the University of Strasbourg, both German Empire

at the time. From the latter he earned his Doctor of

Natural Philosophy degree. Among his teachers were

Ancestral data included below comes from the research by Natalya Evgenyevna Zavoiskaya, who kindly granted usher

permission to use the material [1].

The diminutive of Evgeny.

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BIOCHEMISTRY (Moscow) Vol. 90 Suppl. 2 2025

Fig.  2. V.  A.  Ulyanin, 1928. Source: N.  E.  Zavoiskaya’s per-

sonal archive.

Wilhelm von Bezold, Eduard Hagenbach-Bischoff,

Wilhelm von Beetz, and W. Voigt, outstanding phys-

icists of the time. August Kundt (1839-1894), a re-

nowned German physicist and a student of Heinrich

Gustav Magnus, presumably, had the most important

influence on Ulyanin who worked with him on two

occasions, late in 1880s and in 1890s. In this curi-

ous way, the paths of Evgeny Zavoisky and the USSR

most celebrated physicists symbolically crossed there,

in Munich: Abram Ioffe, farther of the Soviet physics,

studied under the tutelage of and acted as an assis-

tant to Wilhelm Röntgen, most prominent student of

Kundt. Vsevolod Ulyanin made a notable contribution

to experimental physics, namely to researching pho-

to-effect and to investigating potential for the radio

valves to be used in electronic equipment. In 1928,

Kazan hosted the Sixth Conference of the USSR Phys-

icists, invitations were extended to foreign scientists

as well. It was Professor Ulyanin, a pillar of local ac-

ademia, who welcomed Soviet and foreign physicists

to the Conference.

In 1929, Zavoisky published his first paper, On

Gas-Electric Analogies, in The Bulletin of the Kazan

State University Student’s Circle for Mathematics and

Physics. His undergraduate education was approach-

ing a finishing line, Zavoisky, a student of outstand-

ing talent, was recommended to be enrolled in the

postgraduate research program, despite of him inap-

propriately being of neither working class nor peas-

ant origin – a prerequisite for any kind of career to

take place in the post-Revolution Russia. Professor

Ulyanin insisted on him being admitted and took him

as his postgraduate student. For his thesis, the young

physicist chose to investigate potential of radio waves

for studying matter.

Unwavering commitment to his chosen field

of research was one of the cornerstones of his fu-

ture accomplishments. After Ulyanin passed away

in 1931, Zavoisky went to Leningrad to work at the

Central Radio Laboratory, heart of the Soviet radio

physics. There, for 8 months, he studied ultra-short

waves, their generation and reception. Management

of the Laboratory suggested that for his postgrad-

uate thesis he should study super-regenerative re-

ceiver. Zavoisky’s choice was to pursue two lines of

research instead. He committed himself to both the

applied research and to the development of a vacu-

um tube oscillator with an oscillation amplitude and,

hence, grid current and anode current, all to the

maximum extent depending on stability of the oscil-

lating circuit.

In this he succeeded. In the years of 1932-1933

Zavoisky both designed and experimented with a

scheme for an ultra-shortwave super-regenerator, and

developed an apparatus highly sensitive to the prop-

erties of dielectrics used in the oscillating circuit ca-

pacitor. Evgeny Konstantinovich was among the first

to study radio wave absorption in the substance by

means of this method, widely known today, but novel

in the early 1930s. Back then, he was awarded two

inventor’s certificates. Using frequencies in the short-

to ultra-short-wave range, though, could yield no

breakthrough results in his studies of either dielectric

or electrolyte properties. Meanwhile, the laboratory

notebooks of those years, located miraculously in the

archives by I.  I.  Silkin, make it clear that, when ex-

perimenting with oscillation frequency, Zavoisky was

searching specifically for resonances, i.e., areas of

stronger absorption of electromagnetic energy.

In 1933, Zavoisky defended his postgraduate the-

sis and was appointed Associate Professor (Docent) at

the Kazan State University. By mid-1930s, atmosphere

at the University had grown increasingly anxious.

With the University administration in a state of insta-

bility, it was a difficult time for scientific research. In

his memoirs, Zavoisky vividly described those years

at the University (citation by [3]):

“My memories of that administrative chaos are

in bits and pieces. Countless names got jumbled up in

my head: Mislavsky, Galanza, Segal … <…>. Rectors did

not stick around. N-B. Z.  Vexlin was the only one who

made a long-term rector. Exuberant, good hearted,

but burning up with ideas to revolutionize whatever

met his eye, he was convinced that the revolution-

ary spirit was not to be restrained and, astonishingly,

came to realize that physics is to become the leading

KESSENIKH, PTUSHENKOS406

BIOCHEMISTRY (Moscow) Vol. 90 Suppl. 2 2025

science. Yet, a revolutionary as he was, he took it

intohis head to replace Prof.A.  D.  Goldhammer, dean

of the Department of Physics and son of the famous

Prof. D.  A.  Goldhammer, with A.  G.  Sadreyev, an in-

ventor! <…> A few days later Sadreyev was officially

appointed as a dean of the Department of Mathemat-

ics and Physics. God almighty! All this “great mind”

invented was an electric mousetrap and an idea to

use electricity from lightning to power up the first

Five-Year Plan

. He barely had the smarts to calcu-

late cost per lightning strike (seven copecks as of late

1920s in Kazan). <…> How is it that in the “godfor-

saken Tsarist Russia” Lobachevsky, a mathematical

genius, was appointed rector of the University, and

in the post-Revolution Russia a good-natured, simple,

working man became a laughingstock for the sake of

playing democracy? Oh, right! That is a sacrificial of-

fering to the new God – Ideology <…>.

I was called into the rector’s office, where he

informed me with delight about his encounter (at a

comfort station at Narcompros

) with a very distin-

guished man, who called himself K.  N.  Shaposhnikov

a professor of physics. K.  N.  Shaposhnikov briefly ex-

plained how eager he was to go to Kazan, and Vex-

lin immediately counted his blessings. <…> The rec-

tor appointed Prof.  K.  N. Shaposhnikov as a dean of

the Department of Physics. <…> It did not take long

before Shaposhnikov began lecturing first-year stu-

dents on general physics and spoke at the meeting of

the University Society for Mathematics and Physics.

AsIknew what the speech was to be about, I advised

Prof. P.  A.  Shirokov against attending the meeting, but

he had a habit of learning from experience and came

anyway. Ten minutes into the speech, the lector dis-

missed the theory of relativity, and Shirokov whis-

pered in my ear: “I have never thought I will live to

see the University has been disgraced that much, with

professor of physics denying the theory of relativity”.

The lectures he gave to his students were little differ-

ent from the above-mentioned speech, but in them he

was, for the most part, telling jokes (sometimes sharp

ones) and recounting his accomplishments in science.”

Zavoisky appeared to be de  facto the most accom-

plished among the physicists at the University. His in-

nate sense of responsibility made him to compensate

for the lack of support on the part of his superiors

by his own health: he worked with all his might per-

forming scientific research and teaching students. On

the top of that, by mid-1930s he was put in charge

of a research laboratory set up by the University to

study ultra-short waves. “The idea of the laboratory

came out of the impression some of the “wondrous”

properties of ultra-short waves produced. I was called

into the Kuibyshev’s office at the People’s Commis-

sariat of the Workers’ and Peasant’s Inspection

(he

is V.  Kuibyshev’s

brother). When in the building on

Il’yinka Street, I was escorted to an office behind

two padded doors by some men in military tunics

and galliffet

trousers with hidden revolvers bulging

out of their behinds. There was a man sitting behind

the desk, reclined leisurely, heavyset and sleek, and

a military man standing nearby. I was asked, point-

blank, whether the ultra-short waves can kill from a

distance. I answered, that they could not, and I stood

my ground. They lost interest in me right away and

bade me farewell: we will support the laboratory, but

bear in mind, the question asked is of utmost impor-

tance! And I then thought: that is what they do at

the Workers’ and Peasant’s Inspection, where I have

never met a single worker or a peasant!” (cit. ex.[3])

Late in the 1930s, Evgeny Konstantinovich came

within a hair’s breadth of his life being destroyed.

Over a span of two years, in 1937-1938, Zavoisky’s

elder brother and his wife, as well as his brother-in-

law were all arrested. His younger siblings, a brother

and a sister, left the University of their own accord,

to stay out of harm’s way. Zavoisky himself was all

but accused of fascist propaganda for demonstrating

Airy’s spirals (an optical phenomenon observed in

biaxial minerals manifested as light interference pat-

terns of the same shape as swastika) in the lectures

on optical crystallography. Committees, one after an-

other, were “zealously, through a magnifying glass,

investigating crystals in their quest for a swastika

hidden inside, but to no avail, it was not there to

be found” [3]. This preposterous incident prompted

Zavoisky to turn in his resignation, but administra-

tion did not accept it.

Five-Year Plans – a method of planning economic growth over limited periods, through the use of quotas, used first

in the Soviet Union and later in other socialist states.

People’s Commissariat for Education, an antecedent of the later Ministry of Education.

Not to be confused with I.G. Shaposhnikov, Dean of the Department of Theoretical Physics at The Kazan State Uni-

versity in 1939-1941 and in 1946-1948, referred to in Chapter III: First Decades in the Soviet Union Following the

Discovery of Magnetic Resonances in Matter.

A state authority in the Soviet Union with functions similar to those of Russia’s present day Audit Chamber and

Ministry of Labor.

Valerian Kuibyshev, a high-ranking party official, member of the Politburo of the Communist Party of the Soviet Union

and a counselor for economic affairs to Joseph Stalin.

A style of trousers in the Soviet Army uniform: similar to riding breeches, fitting the knees and below and expanding

from above the knees.

DISCOVERERS OF MAGNETIC RESONANCE IN MATTER S407

BIOCHEMISTRY (Moscow) Vol. 90 Suppl. 2 2025

Fig.  3. Left to right: S.  A.  Altshuler, E.  K.  Zavoisky, B.  M.  Kozyrev. Kazan, 1968. Source: N.  E.  Zavoiskaya’s personal archive.

Evgeny Konstantinovich married Vera Konstanti-

novna Trufanova. The family’s day-to-day living was

anything but simple. In 1936, they lost their first-born

daughter to a decease.

Since 1933 Zavoisky had been working together

with B.  M.  Kozyrev, a physical chemist. In 1935, he

found another longtime associate in S.  A.  Altshuler

(Fig.  3), a brilliant physicist who will carry on Za-

voisky’s lifework. At the time, Altshuler was newly

appointed as an Associate Professor (Docent), Depart-

ment of Mathematics and Physics, upon finishing his

postgraduate research program under the tutelage of

I.  E.  Tamm.

Meanwhile, in 1939, results of the I.  Rabi’s fruit-

ful research on nuclear magnetic resonance in mo-

lecular beams were published [4]. Both Zavoisky and

Altshuler developed a strong interest in the subject,

as both had previously performed experiments with

resonance phenomena of their own: Zavoisky, by

that time, had invented a highly sensitive method for

studying radio frequency resonance absorption, and

Altshuler had just defended his postgraduate thesis

on the theory of nuclear magnetic moments. Kozyrev

shared their enthusiasm. The three physicists were

determined to detect resonance of nuclear magnetic

moments in matter rather than in molecular beams,

the latter essentially being an ordinary task inconve-

nienced by the need for a cumbersome vacuum appa-

ratus. To generate a magnetic field, they used a small

du Bois–Reymond-type electromagnet with a horse-

shoe-shaped yoke and rather narrow air-gap of no

more than 4 to 5  cm (1.5 to 1.9  in) in diameter and 3

to 4  cm (1.2 to 1.6  in) in length (Fig.  4). At the same

time, the “grid-current” method (when absorption

is measured by the changes of the grid current of

a vacuum tube oscillator) they used to measure res-

onance absorption, was extraordinarily sensitive for

that time. Based on the laboratory notebook records

and on their own recollections of the time, Zavoisky’s

co-authors [5] both later asserted that Evgeny Kon-

stantinovich had been observing nuclear, or proton,

magnetic resonance on more than one occasion.

Zavoisky performed measurements himself using the

frequency range of 6 to 8MHz in a magnetic field of

approximately 1500 G intensity.

Fig.  4. The du Bois–Reymond-type electromagnet, employed

by E.  K.  Zavoisky, S.  A.  Altshuler and B.  M.  Kozyrev in their

experiments in late 1930s. Kazan, E.  K.  Zavoisky Laboratory

Museum. Source: I.  I.  Silkin’s personal archive.

KESSENIKH, PTUSHENKOS408

BIOCHEMISTRY (Moscow) Vol. 90 Suppl. 2 2025

It was unclear whether it is at all possible to

observe NMR in substances (in “condensed matter”),

a circumstance putting considerable psychological

pressure on the experimenters. Some theoretical

physicists, like Heitler or Teller [6], came as far as

to predict that, having absorbed a small amount of

energy from electromagnetic field, a spin system

would achieve a saturated, i.e., overheated, state. In

quantum theory, when a system is saturated, ener-

gy levels, which correspond to different orientations

of the nuclear spin, hence, of the magnetic moment,

are equally populated. C.  J.  Gorter, a Dutch theoretical

and experimental physicist, was already struggling to

detect nuclear and electron paramagnetic resonance

in matter at the time, but to little avail, as the cal-

orimetric method he used proved to be ineffective

in this instance and took his experimentation on

the wrong path [7, 8]. Zavoisky came much closer to

the discovery. He suggested using the “grid current”

method permitting to detect absorption of energy in

a paramagnetic substance through the changes in

responding behavior of a radio circuit, an approach

considered to be the most sensitive up to the present

day. The “saturation avenue of exploration” showed

promise. Today, it is common knowledge, that there

are more than one mechanism for the spin to give off

energy to the crystal lattice, all providing sensitivity

high enough for the NMR to be observable: spin ener-

gy can be converted into kinetic energy of conduction

electrons or, in liquids, into thermal motion of mole-

cules, among other possibilities. If only the pioneers

were aware of that back then! Later on, after the dis-

covery had been made, with regard to different other

research, Evgeny Konstantinovich instructed his col-

leagues, that once energy is given off to the system,

the system would find its way to distribute it among

the multiple degrees of freedom.

Phenomena, considered as a clear indication of

NMR detected in matter now (with works by Purcell

and Bloch published in 1946), were not enough of

foundation for the group of physicists at the Kazan

University to publish their findings back then. For

the reasons unknown at the time, the resonant signal

was detected sporadically, depending on a number

of random factors, like accidental vibrations of the

apparatus. Hence, influence of the magnetic field in-

homogeneity applied to the sample was highly incon-

sistent, unpredictable, and hard to measure. In most

cases, spread in the field intensity values, of which

resonant frequency was a function, was too wide,

and therefore the line width broadened to become

undetectable. The du Bois–Reymond-type magnet

was not absolutely reliable in terms of its mechani-

cal integrity, while optimum inhomogeneity value in

the air gap of this miniature magnet was on itself

too big. This circumstance did not permit Zavoisky

to announce the discovery, but he was still persistent

in his experiments. Meanwhile, in 1945, his Ameri-

can colleagues were “hunting” for NMR in the air

gap of a large electromagnet used in a cyclotron to

study cosmic rays. The gap was up to 60 to 70cm (23

to 21  in) in diameter and provided, if compared to

Zavoisky’s magnet, two to three orders of magnitude

more homogeneous magnetic field within a specimen

with a hundred to a thousand times lower spatial dis-

persion of the magnetic field intensity.

Basically, Bloch and Purcell had only one diffi-

culty to overcome: they needed to find the magnitude

of electromagnetic current required for the field to

reach the resonance value (it was enough to rough-

ly estimate strength of the field for the cyclotron to

work). In the USSR, there were five or six magnets

comparable to the one used by the American physi-

cists, but they were all available to only few scientists

engaged in a totally different line of research.

The plot thickened as the World War II broke

out and interrupted the search for NMR effects in an

absolutely ludicrous way. Before the war, the Univer-

sity scientific brainpower was not at its best, while

Zavoisky needed accomplished physicists to partake

in his experiments. One would think that relocation of

the Leningrad Physical-Technical Institute (PTI) of the

USSR Academy of Sciences from Leningrad to Kazan

would reinforce the research. The reality proved oth-

erwise. For the high commission of academicians and

professors of this scientific institution one glance was

enough to give the verdict: this primitive device is

unfit for scientific purposes. Evgeny Konstantinovich

reminisced: the apparatus was dismantled, or, rather,

it was destroyed, its owner not present and in oppo-

sition to this act of vandalism; in the vacated office,

for two years, PTI’s employees had been redeeming

their bread ration coupons.

S.  I.  Altshuler volunteered for the front lines.

Zavoisky was redeployed to assist with the defense-

related project. On paper, the research pertained to

radio location, but de  facto Zavoisky was compelled

to assist V.  K.  Arkadyev, a corresponding member of

the Academy of Sciences, with his rather hopeless re-

search [9]. And yet, Arkadyev’s project was provided

with generous financing (“5000  RUB for special work”)

and was nominally developed at the P.  N.  Lebedev

Physical Institute (LPI) of the Academy of Sciences

[10]. To sustain the University staff amid the famine

and chaos of the war, Zavoisky and his colleagues

worked in the fields – agricultural allotments the

University had to provide for its needs – harvesting

crops and firewood. Evgeny Konstantinovich was of-

ten in charge of those survival efforts. Institutes of

the Academy of Sciences, relocated from Moscow and

Leningrad to Kazan, got to occupy a good number of

the University’s buildings. One should bear in mind,

DISCOVERERS OF MAGNETIC RESONANCE IN MATTER S409

BIOCHEMISTRY (Moscow) Vol. 90 Suppl. 2 2025

that this arrangement went far beyond overcrowd-

ed premises. All of the buildings belonging to the

Kazan University were reallocated to the Academy

of Sciences. Only some of them, but mostly offices,

sometimes floors in separate buildings, were left at

the disposal of the University “to ensure the academ-

ic process continued” [11]. At their home, employees

of the University were at the mercy of the Academy

with very little control over the situation, if any. They

were not allowed to the majority of the buildings.

At war times, collateral damage is unavoidable. But

why destroy a fully functional apparatus!

In 1943, following the Academy’s institutes relo-

cation back where they belonged, Arkad’yev’s labo-

ratory included, Zavoisky resumed his experimental

work and insisted on a new research plan to be ap-

proved. This time, he meant to study parallel and,

most importantly, perpendicular fields absorbing

radio-wave energy. Zavoisky suggested placing vials

containing paramagnetic salts and salt solutions, as

well as metal powders, inside the oscillating circuit

induction coil, as there the magnetic component of

electromagnetic oscillations was the strongest.

Up to this day, it is an open question as to why

Zavoisky’s discovery of EPR did not lead him straight-

away to observing NMR as well. The question might

seem relevant from today’s perspective only, as

phenomena obvious to modern scientists were not

known to Zavoisky or to his contemporaries. One of

such phenomena is a wide diversity of magnetic res-

onance manifestations and related research, a reali-

ty the today’s experimenters are accustomed to. It is

evident now, that the NMR spectroscopy as applied

to liquids or solids, organic or inorganic materials,

and so on are each a distinct line of research with

its own nature and experimental approach. As would

be shown later, after Rabi had discovered magnetic

resonance phenomenon, it had still to be rediscov-

ered over again in each new substance. There was

no clear differentiation between, at the very least,

nuclear magnetic, electron paramagnetic, or ferro-

magnetic resonance experimentation in the times,

when the first discoveries were made. In the scien-

tific magazines of those years you can see findings

on EPR, NMR, and FMR spectroscopy often published

in the same section. Comparing to geographical explo-

rations, a discovery of the South Pole does not imply

an expedition should be immediately sent to find the

South Magnetic Pole, the Pole of Cold, or the Pole of

Inaccessibility. Discovering Antarctica is considered

a great endeavor of its own merits with these other

“points on the map” gaining explorative interest later.

Another phenomenon affecting modern perspec-

tive is the focus on success, awards, and priority rule,

characteristic of the present-day science. It would be

unreasonable, though, to ascribe motivations com-

mon in the 21st century to the pioneers of magnetic

resonance making history in the 20th century. It is

hard to imagine Zavoisky being driven by the urge to

win the race for all possible resonance phenomena,

when performing his experimental work. Meanwhile,

his discovery of EPR opened up as much new ave-

nues for research as any other, though hypothetical

at the time, resonance phenomenon would.

Indeed, Zavoisky’s very first experiments with

paramagnetic substances showed much promise.

In the period of late 1943-early 1944, experiments

were performed sporadically, a casualty of the war.

Yet, it was in those years that, in his notebooks,

he first mentioned resonances for the fields of the

order of 12 Oe and excitation frequency of the or-

der of 35 MHz, detected with a radio-frequency coil

aligned perpendicular to the constant magnetic field.

To generate constant field Zavoisky used two identical

circular magnetic coils placed symmetrically along a

common axis, a Hemholtz pair (Fig.  5), instead of the

magnet he had previously employed. Radio-frequency

constantly increased, the resonance appeared at ap-

proximately several dozen megahertz in the magnetic

fields of two to three dozen gauss [9].

The scheme allowed for the current in the coils

to be modified repeatedly by means of sawtooth volt-

age supply. With a low-frequency sinusoidally modu-

lated field added to the constant field, sensitivity of

the method grew dozens of times higher. The device

allowed for an audio-frequency oscillator to be con-

nected to the Hemholtz coils via the capacitors and in

parallel with the storage battery, a DC power source,

to obtain a low-frequency signal (resulting from de-

modulation of the oscillator signal), which was ready

to be filtered out of noise.

Reproducibility, that is repeatability of the re-

sults, was strong enough this time with the laborato-

ry notebook entries on resonances recurring repeat-

edly. A simple calculation showed that for some of

copper, manganese, and chromium salts maximum

of absorption corresponded to the resonance of the

magnetic moment, which was close or even identi-

cal to the magnetic moment of the free electron. The

most telling was position of the peak in the absorp-

tion curve A  (H), sawtooth current I fed to the coil,

in which A was the signal intensity as registered by

the recorder and H  =  kl was the magnetic field inten-

sity (Fig.  6). The curve was plotted point by point by

means of a galvanometer or on the moving film of

the cathode-ray oscillograph with the Hemholtz coils

direct current, i.e., field intensity, slowly changing.

The calculation definitively demonstrated that the

phenomenon observed was a resonance absorption

of the energy from electromagnetic oscillations by

the electron magnetic moments of a transition metal

(copper, manganese and chromium) ions contained

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BIOCHEMISTRY (Moscow) Vol. 90 Suppl. 2 2025

Fig.  5. The apparatus by means of which E.  K.  Zavoisky observed EPR for the first time ever, as reconstructed

by I.  I.  Silkin. Kazan, E.  K.  Zavoisky Laboratory Museum. Source: I.  I.  Silkin’s personal archive.

Fig.  6. Title page and one of the pages of E.  K.  Zavoisky’s doctoral dissertation. Source: V.  V.  Ptushenko’s personal archive.

DISCOVERERS OF MAGNETIC RESONANCE IN MATTER S411

BIOCHEMISTRY (Moscow) Vol. 90 Suppl. 2 2025

in their salts. The spectroscopic factor g, or g-factor

as it is known today, of a free electron (its magnetic

moment equal to 1 Bohr magneton or β) is almost 2.

Zavoisky’s experiments showed the g-factor, indeed,

approximating2. With the frequencyƒ being changed,

the peak position shifted proportional to the change

in the excitation frequency for the maximum of A

to be obtained once the condition ƒ  =  (gβ/ h)H

max

was

met, in which h was the Planck’s constant.

In the Zavoisky’s first experiments, the spectral

line, an essential EPR attribute, at the coordinates of

A  (H) was broad enough for non-negligible absorption

in the low-frequency alternating magnetic field to re-

main far from the resonant field H

max

(for example,

both at H  =  0 and at H  =  2  H

max

). In May 1944, hav-

ing finalized the first stage of his research, Evgeny

Konstantinovich submitted his doctoral dissertation to

the Physical Institute of the USSR Academy of Scienc-

es, Moscow (Fig. 6).

Zavoisky did his experimental work in the cir-

cumstances hard to survive in, let alone to advance

the science. His major competition in the magnetic

resonance research, C.  J.  Gorter, lamented that the sit-

uation in the Netherlands occupied by Nazis made it

extremely difficult to perform experimental research.

Unbeknownst to Gorter at the time (most likely the

Dutch physicist came to know of the Zavoisky’s work

not before 1945), his colleague in the war-time Kazan

continued his experimentation in between managing

the University’s subsistence farm, cultivating the fam-

ily’s kitchen garden, and hunting for rooks (for food).

To assemble his new apparatus Zavoisky had to pro-

cure parts himself or with the help of his students,

employed in the defense industry, his prior associa-

tion with the radio location project being of no help.

In his memoirs (published after his death), Zavoisky

reminisced about how hard it was to get hold of ev-

ery piece of equipment [12]. In 1943, Evgeny Konstan-

tinovich returned to teaching as well.

Ya.  I.  Frenkel (Fig.  7), the USSR’s most renowned

theoretical physicist and head of the Department of

Theoretical Physics at the Leningrad Physical-Techni-

cal Institute, was the first to develop interest in the

discovery of EPR and to give it a theoretical formu-

lation [13]. He definitively confirmed the nature of

the observed phenomenon as an electron spin reso-

nance. His interpretation of the resonance line shape,

though, was rather formalistic. Yet, his endeavor fa-

cilitated acknowledgment of the Zavoisky’s work by

the scientific community.

In 1944-1945, Evgeny Konstantinovich was a fre-

quent visitor to Moscow, defense of his dissertation

continuously deferred. Some of academicians, scien-

tific elite, no less, remained largely skeptical of it

being possible for a little-known physicist to observe

such a fine phenomenon, as perceived back then,

all by himself and in the direst of circumstances.

Optical physicists doubted it was within the realm of

possibility to directly observe such low-energy quan-

tum absorption. This quantum phenomenon in the

Zavoisky’s experiment corresponded to the Zeeman

effect, or hyperfine splitting of a spectral line, and it

was known to be observable in optical spectra of va-

pors or gases placed in a magnetic field. “Professional

naysayers” were in abundance too, they always are,

rejecting all that was created by the minds other than

from Harvard, Oxford, Berkeley or, if nothing else,

from Leningrad Physical-Technical Institute, Lebedev

Physical Institute, or Kharkiv Institute of Physics and

Technology.

Help came from the Soviet Institute for Physi-

cal Problems (IPP), namely from Peter Kapitsa and

Aleksander Shalnikov (Figs.  8 and 9). To address the

doubts, they invited Zavoisky to the IPP to reproduce

his experiments using vast resources the Institute

could offer. He was now able to replicate his exper-

imentation, firstly, in the higher frequency range of

up to 2.75  GHz, corresponding to higher fields of up

to 1200  Oe; and secondly, over a wider range of tem-

perature, with liquid hydrogen temperature at −253°C

or 20  K. Next, he reproduced the experiment using

the boil-off vapors from liquid helium as a coolant,

thus obtaining the temperature of −269°C or 4.2  K.

Shalnikov, a virtuoso experimenter, assisted Zavoisky

in person and was astonished by the extraordinary

sensitivity of this method. The apparatus was assem-

bled and given a test run in January of 1945, with-

in a couple of weeks! The EPR phenomenon in the

same substances Zavoisky investigated in Kazan was

Fig.  7. Ya.  I.  Frenkel. Source: The Free Encyclopedia; URL:

https://fr.wikipedia.org/wiki/Yakov_Frenkel.

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BIOCHEMISTRY (Moscow) Vol. 90 Suppl. 2 2025

Fig.  8. Left to right: L.  A.  Artsimovich, M.  A.  Lavrentyev,

N.  N.  Semenov, P.  L.  Kapitsa. 1956. Source: Peter  Kapitsa

Memorial Museum of the Institute for Physical Problems.

Provided by T.  I.  Balakhovskaya.

Fig.  9. Standing (left to right): A.  I.  Alikhanov, P.  Savich;

seated (left to right): A.  I.  Shalnikov, L.  D.  Landau. Moscow,

Institute for Physical Problems, 1946. Source: N.  A.  Shalniko-

va's personal archive.

officially confirmed, all skeptics were proven wrong.

Supported by Ya.  I.  Frenkel, Zavoisky, finally, defend-

ed his doctoral dissertation

, with E.  I.  Kondorsky

and A.  I.  Shalnikov participating in the capacity of

dissertation opponents.

Unfortunately, official acknowledgement of the

discovery brought about only little improvement, if

any, to the Zavoisky’s working environment, or to his

living circumstances, for that matter. On the bright

side, Semen Alexandrovich Altshuler, a close associ-

ate of him, came back from the front lines of war.

Together, the three of them, Altshuler, Kozyrev, and

Zavoisky, soon determined the mechanism behind the

broadened profile of spectral lines. They attributed

the phenomenon to interaction between the magnetic

moments of unpaired electrons in paramagnetic salts.

In 1947, having no knowledge of the James Griffiths’s

recent discovery, Zavoisky detected ferromagnet-

ic resonance. Evgeny Konstantinovich was formally

offered his own laboratory at the recently re-estab-

lished Kazan Physical-Technical Institute of the Acad-

emy of Sciences (in 1984 named after E.  K.  Zavoisky).

Yet, the provided financing was negligible. The let-

ter, dated November 11, 1946, he and his colleagues,

I.  G.  Shaposhnikov, S.  A.  Altshuler, and B.  M.  Kozyrev,

wrote to S.  I.  Vavilov, president of the Academy of

Sciences, was most illustrative of the circumstances

he had to grapple with in those years. In the letter,

the accomplished scientists asked Vavilov for assis-

tance with procuring an electromagnet, essential for

carrying out further research on electron and, more

importantly, nuclear magnetic resonance. Official re-

quests for a magnet, or at the very least for the com-

ponents to assemble it with, submitted to both local

authorities and to the Academy of Sciences had all

proven unhelpful (published in: [9]). Meanwhile, by

the end of the year 1946, nuclear magnetic resonance

had already been discovered, its potential for further

scientific advancements was obvious enough for the

physicists in the West to start massively researching

the relating phenomena [14, 15].

The Zavoiskys lived in two storage rooms some-

what redesigned to serve as living quarters. Heat

coming from a potbelly stove barely lasted for a

couple of hours with the opposite wall being freez-

ingly cold all the time. Zavoisky’s wife and daugh-

ter were both ill, and his home was absolutely unfit

for any serious work. The University administration

refused to help the esteemed scientist to improve

his living conditions, as his situation was referred

to in the official documents. Altshuler reminisced,

that the post-war hardship was not blame, rather it

was the attitude on the part of the University’s rec-

tor, K.  P.  Sitnikov, for whom Zavoisky’s integrity was

hard to put up with ([16]). Meanwhile, dissertation

Evgeny Konstantinovich had recently defended draw

some serious attention. News of a gifted experiment-

er reached I.  V.  Kurchatov, head of the Soviet nuclear

program. In 1947, he suggested that Zavoisky should

join his research team.

According to the memoirs of his colleagues at

the nuclear research laboratory, Zavoisky was as-

signed the task of calculating shockwave (initiated

by the chemical explosion) velocity enough to com-

press the subcritical sphere of a fissile material in

the atomic bomb into a supercritical mass. In his

experimentation, Evgeny Konstantinovich employed

electromagnetic methods, his research being one of

The transcript of the defense was published almost in its entirety in the book by N.  E.  Zavoiskaya [26].

DISCOVERERS OF MAGNETIC RESONANCE IN MATTER S413

BIOCHEMISTRY (Moscow) Vol. 90 Suppl. 2 2025

the several with the same goal carried out simultane-

ously. Zavoisky appreciated complexity of the project

he was assigned to, but felt profoundly uncomfort-

able about the ultimate goal of the nuclear program.

The family moved to Moscow, where he was finally

offered a decent apartment, while Evgeny Konstan-

tinovich left for Arzamas-16, now Sarov, to join the

nuclear program. His daughter reminisced: “That was

a dark period of my father’s life. I was too young at

the time to comprehend the high price he had to pay

for our family’s well-being. He did not like revisiting

those painful years, neither was he allowed to, as his

work was classified. In February 1949, he wrote to

my mother, who was giving birth to their son at a

maternity hospital “… I would not like him to become

a physicist: this science grows increasingly despica-

ble, he would be much better to engage in human

physiology or astronomy” [17]. In 1951, Zavoisky, at

long last, managed to break away from Arzamas-16

and from atomic weapons development, something

he had been asking Kurchatov for. From then on, for

many years, he had been working at the Laborato-

ry of Measuring Instruments of the USSR Academy

of Sciences, several years later changing its name to

the Institute of Atomic Energy (IAE) and ultimately

named after I.  V.  Kurchatov.

In seven years Zavoisky did not published a sin-

gle paper. For seven years he had been working hard

together with a large team of physicists and engi-

neers to create spin-polarized atomic beams, an unre-

warding, yet necessary process. In 1956, a source for

spin-polarized protons and deuterons was developed.

In parallel, Evgeny Konstantinovich had been de-

veloping experimental methods for studying ultrafast

processes, a certain follow-up to his work in the So-

viet nuclear program. In 1953, Zavoisky was elected

a Corresponding Member the Academy of Sciences of

the Soviet Union.

His experimental work on the nuclear project

showed, however, that his electromagnetic method,

with the equipment available, was not the most effec-

tive for studying shockwave propagation. Soon after-

wards, Zavoisky set out to study electrical discharges.

To that end, together with S.  D.  Fanchenko he de-

signed a multi-stage cascaded optoelectronic convert-

er. At every stage of the cascade there was a pho-

tocathode (a cathode emitting electrons when struck

by light) and a compact linear accelerator with an

output phosphor screen. When hitting the phosphor

screen, an accelerated electron produced a brighter

than originally flash of light. Skillful experimenters,

Zavoisky and Fanchenko used simultaneously five to

six of such cascaded stages with time-dependent light

pulses remaining largely undistorted. The optoelec-

tronic converter allowed for the electron image to be

analyzed in time and scanned in space. Zavoisky also

designed a new method for detecting ionizing par-

ticles, which he named a scintillation chamber [18].

Evgeny Konstantinovich together with M.  M.  But-

slov and colleagues made some significant improve-

ments to the design of a multi-stage high-resolution

time-analyzing image intensifier tube. The enhanced

scheme permitted observing processes with 10

−14

time resolution. The new apparatus, for example,

helped to establish that the glow phase in the minia-

ture spark discharges may last for as little as 10

−10

a thousand times less than it had initially been be-

lieved. This finding was at the root of using opto-

electronic converters for counting charged particles.

Cascaded multi-stage optoelectronic converters found

numerous applications in studying laser pulses, in as-

tronomy, in high-speed photography of matter shock

disintegration process, etc. [19].

It is worth noting here, that Zavoisky was among

the first laureates of the Lenin Prize, when it was

re-established in the USSR in 1957. He was awarded

the Prize for his discovery of electron paramagnetic

resonance, a decision welcomed enthusiastically by

the great majority of the Soviet scientific community.

Evgeny Konstantinovich, an outstanding experimenter

and a wonderful, considerate, and principled person,

was widely respected and loved.

In 1957, Zavoisky focused efforts on investigating

plasma phenomena. Among other things, his research

team worked to achieve controlled nuclear fusion re-

action. Numerous problems stood in the way, one of

them there being absence of an obvious method for

pumping energy into plasma to heat it. As a possible

solution, Zavoisky suggested using magneto-acoustic

resonance manifesting itself when the frequency of

magnetic field oscillations coincided with the one of

many frequencies of the charged particle self-oscil-

lations in a plasma. He thus discovered a complex

and multifaceted phenomenon of turbulent heating

characterized by the transfer of energy between the

regular oscillations and chaotic oscillations of the

charged particles or charged-particle bunches. This

particular research project proved to be a strong

start for a good many prominent experimental phys-

icists, like A.  P.  Akhmatov and M.  B.  Babykin to name

a few. L.  I.  Rudakov, soon to be a renowned theoreti-

cal physicist, was also on the Zavoisky’s team.

In 1964, Evgeny Konstantinovich was elected

a full member of the USSR Academy of Sciences,

breakthrough results his research team delivered

were recognized. In that period, Zavoisky set direc-

tions for the advances in plasma physics in the USSR

and beyond, across the Soviet bloc. His vision of

this branch of physics development included, among

many other things, establishing an Institute for

Hot Plasma Physics in the USSR, an idea that found

little support, however. In 1967, he proposed that

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BIOCHEMISTRY (Moscow) Vol. 90 Suppl. 2 2025

the Soviet and Czech physicists should join their sci-

entific efforts, the latter being at the cutting edge of

plasma research at the time. Thwarted by the turmoil

of the Prague Spring, 1968, though, this cooperation

never happened.

In 1967, Evgeny Zavoisky was cut off all commu-

nication with his colleagues in the West for reasons

still unclear. Only thrice in 20 years had he been al-

lowed out of the country, despite invitations to the

prestige international conferences, both on electron

paramagnetic resonance and on plasma physics, ex-

tended to him on a regular basis. Meanwhile, other

USSR scientists of the comparable caliber and repute

were much more frequent participants on the in-

ternational stage. His classified work for the Soviet

nuclear project in the 1940s can hardly be blamed,

as his Arzamas-16 colleagues suffered no such obsta-

cles. Frustratingly, on quite a number of occasions,

Zavoisky was authorized to accept an invitation and

speak at a conference outside the country only to

be informed days before the departure, all of a sud-

den and after months of preparation, that the deci-

sion had been reconsidered, his trip cancelled. Three

times only he delivered his paper in person: in 1961,

Salzburg, Austria, in 1965, Culham, Great Britain, and

in 1967, Prague, Czechoslovakia.

A scientist of overwhelming, prominent talent,

many would say a genius, Evgeny Konstantinovich

unraveled puzzles never approached before, at

times much to annoyance of some of his colleagues

and rivals – such an observation was shared by

G.  A.  Askaryan [20], who knew Zavoisky well through

the plasma research. Zavoisky treated all his col-

leagues with unvarying kindness and respect, with-

out exception. He was a true intellectual, a living

example of devotion to Truth and to Science. “Some

researchers joked, that Zavoisky was the only aca-

demician at the Institute who indeed worked there”

[21]. An episode, R.  A.  Antonova related in her rem-

iniscences about Evgeny Konstantinovich, would me

the most descriptive of him:

“It was mid-1960s. G.  I.  Rostomashvili and I came

to the I.  V.  Kurchatov IAE to get to know some of the

methods used by Evgeny Konstantinovich and his

team in plasma experimentation, and to discuss our

research. <…> We were warmly welcomed into his

laboratory and were given directions to the office

Evgeny Konstantinovich worked in. We felt awful-

ly shy of meeting the “father of paramagnetic res-

onance”. We knocked slightly on the door. Someone

invited us in. Once inside, we found ourselves in a lab-

oratory room rather than in an academician’s office,

as one would expect. Busy with one of the apparatus-

es, the only person in the room was a middle-aged

experimenter, dressed in a black laboratory gown, a

soldering iron in his hand. He was re-soldering to-

gether some pieces of a scheme. We immediately felt

at ease and asked simply where to find academician

Zavoisky. His astounding reply took us aback: “I am

listening”. We were speechless with astonishment.

Evgeny Konstantinovich put aside his soldering iron

and looked at us, his eyes slightly squinted, kind, and

tranquil.” [22]

In his last years, Zavoisky experimented with

relativistic electron beams, i.e., streams of electrons

moving with the speed comparable to that of light,

as a method for igniting fusion. Also, in those years

he approached the problem of high-temperature

superconductivity.

His last years, regrettably, were full of hindranc-

es impeding his life and work. As mentioned above,

he was repeatedly denied international speaking op-

portunities in quite unceremonious manner, at the

eleventh hour. He thus never got to speak at the con-

ferences in Japan, in 1970, and in the USA, in 1971.

Uncannily refused the right to travel the day he was

due to get his papers at the State Committee on the

Utilization of Atomic Energy, Evgeny Konstantinovich,

no doubt, felt deeply insulted. When he came to col-

lect his papers for the trip to the US, he was not al-

lowed inside the office, no explanation offered. In the

eyes of a bureaucrat, an ordinary Soviet man, obvi-

ously, knew no other attitude. “Why are you here?

You are not going anywhere,” so much for explana-

tion. Someone decided that Evgeny Konstantinovich

must not travel abroad. Most importantly, no one in

the IAE management would not or failed to, at best,

to defend the right of the Institute’s most prominent

scientist to deliver his papers to his colleagues at

the international stage in person. After one of such

incidents, Zavoisky, 64, resigned. Straggling to grasp

the motive behind, some of his colleagues attribut-

ed his unexpected resignation, at the very peak of

his career, to the persistent refusals to his requests

for permission to travel abroad. G.  A.  Askaryan, for

example, believed, according to his reminiscences,

that Zavoisky thus protested against violation of his

individual rights. The reality was far more complex,

though: Evgeny Konstantinovich was repeatedly re-

fused not only to travel to present papers by the

State Committee, but, most importantly, he was re-

peatedly refused financing by the Institute. Basically,

at the IAE, with full-scale research on the controlled

thermonuclear synthesis launched and generously fi-

nanced, Zavoisky’s laboratory struggled to get financ-

ing essential for any serious experiment to be car-

ried out. Many years later, V.  L.  Ginzburg recounted

his conversations with Evgeny Konstantinovich: “We

both were completely candid. He should not have

left the Institute. He could have carried on working.

Artsimovich resorted to playing dirty tricks against

him? So what? He should have carried on working.

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BIOCHEMISTRY (Moscow) Vol. 90 Suppl. 2 2025

He had pride. I do not have pride, you know. I cannot

afford pride” [23]. If Zavoisky would be a theoretical

physicist he could have indeed “carried on working”.

Yet, he was an experimenter. The outdated apparatus

he had at his disposal exhausted its capacity for pro-

ducing data for new research, assembling of a new

one was put on hold indefinitely. Zavoisky literally

had no options left, apart from moving focus to a

different field. Basically, he found himself trapped in

a situation very similar to his circumstances in 1947.

This time, however, he had nowhere to go. Kurchatov,

who made a difference back then and whom Evgeny

Konstantinovich, by accounts of many, respected

deeply, had passed away. Denied essential resources

to continue his work, Zavoisky left the Institute. He

was 64, in the prime of a true scientist’s life.

In 1972, after he had retired, Evgeny Konstan-

tinovich suffered a severe heart attack. A man of

honor, Zavoisky, still in recovery, was one of the few

ready to come to the defense of Andrey Sakharov in

1973, when the latter became the target of official

censure and harassment. His poor health, however,

did not allow him to do much. In that period, Evgeny

Konstantinovich finished writing his reminiscences

about the Kazan University and some of his col-

leagues. He never stopped working on the new ideas

in plasma physics, although, retired, it was harder to

get them published. In his last year, Zavoisky worked

as Editor-in-Chief for the Advances in Physical Scienc-

es magazine (Physics-Uspekhi). Like with everything

he ever did, he took this last commitment seriously,

devoting much of his time and intellect to the job.

As ever, his personality and attitude made lasting

impression upon his co-workers. L.  I.  Kopeykina [24],

managing editor at the Advances in Physical Scienc-

es thus reminisced about her experience of working

with Zavoisky:

“I remember meeting Evgeny Konstantinovich. It

was April, 1976, soon after the Presidium of the Acad-

emy of Sciences appointed him as an Editor-in-Chief.

I was in the editorial office, when I heard someone

knock on the door delicately, and then a man came in,

of short stature, his hair streaked with gray, his eyes

radiating kindness, with an element of shyness about

him. He greeted me politely. I offered him a seat.

He took a seat and said: “I am Zavoisky.” At first, it

felt awkward <…> I expected the new Editor-in-Chief

to ask the staff to his home office to meet him. Evg-

eny Konstantinovich, however, made it clear right

away, that he would prefer to meet with the staff at

the editorial office to prevent visitors from finding

the doors closed during office hours and to make

sure they can always get assistance they came for.

His attitude stunned me: he was a prominent

scientist, an academician, his schedule always tight,

he was advanced in his years, his health failing him,

and, on top of that, he lived a long way from the

editorial office. What amazed me most, though, was

his kind and caring manner, his respect for other peo-

ple’s time.

Business matters were discussed last. Evgeny

Konstantinovich first got acquainted with the edi-

torial staff, wages, and responsibilities of each and

every member of the team, and only after that he

delved into the day-to-day matters of the editorial

office.” [24]

On October 10, 1976, Evgeny Zavoisky, 69, passed

away.

Throughout his life, after 1953, Evgeny Konstan-

tinovich never severed his longstanding friendly or

scientific ties with his fellow physicists at the Kazan

University or with many Soviet scientists sharing his

interest in magnetic resonance. Appointed by the

Academy of Sciences, Zavoisky oversaw development

of the Kazan Physical-Technical Institute. Among oth-

er things, he facilitated constructing its new building

at the Siberian Route (Sibirsky Trakt).

In 1969, an international conference took place

in Kazan to mark 25th anniversary of the EPR dis-

covery, an important milestone for the entire mag-

netic-resonance community. Zavoisky, one of the key

persons in the history of this discovery, was highly

praised for his pioneering work on the phenomenon

by Cornelis Gorter and Alfred Kastler, a Noble Prize

laureate “for the discovery and development of opti-

cal methods for studying Hertzian resonances in at-

oms”, both speaking in Kazan. Alfred Kastler ended

his speech by saying: “Dear colleagues! As our plane

approached the Kazan airport, it flew over the Volga

River. For us, to see this river with our own eyes was

emotionally overwhelming. Beginning from a small

spring, The Volga then grows wider and wider, until

it becomes a mighty river, deep as an ocean. So does

paramagnetic resonance. It began from a small exper-

iment, performed here, in Kazan, 25 years ago. Now

that the years have passed it became a vast scientific

field, rich in research and papers…” [25]

Zavoisky, in his speech, offered his ideas on two

promising, groundbreaking experiments on magnetic

resonance.

As the scientific community bid its final farewell

to the late father of EPR, the question “Why was

not Zavoisky ever given the Nobel Prize for his dis-

covery?” bewildering many of his colleagues across

the world loomed large, prompting the search for

the answer. N.  E.  Zavoiskaya, daughter of Evgeny

Zavoisky, collected a huge amount of first-hand ac-

counts to get at least some understanding [26].

S.  A.  Altshuler and B.  M.  Kozyrev [5, 27, 28], as well

as many other scientists, presented their thoughts and

evidence in their contributions to the “Magician of

Experiment” volume, a collection of essays, published

KESSENIKH, PTUSHENKOS416

BIOCHEMISTRY (Moscow) Vol. 90 Suppl. 2 2025

to commemorate Zavoisky. So did S.  V.  Vonsovsky, a

patriarch of the Soviet magnetism research, who, in

association with Cornelius Gorter, the Netherlands,

and Ivar Waller, a Swedish theoretical physicist and

the author of the first theory of paramagnetic relax-

ation, nominated E.  K.  Zavoisky to the Nobel Prize.

V.  L.  Ginzburg [29] also wrote about his nominating

Zavoisky to the Nobel Prize. The Nobel Prize history

of magnetic resonance is recounted in more detail in

the next section. At the international conference, held

in Heidelberg, Germany, in 1976, the Prize Committee

of the International Society for Magnetic Resonance

(ISMAR) decided to award the ISAR Prize for the year

1977 to Evgeny Zavoisky. Sadly, the Award was given

to him posthumously.

In 1991, the International Zavoisky Award was es-

tablished to recognize outstanding research and devel-

opments in the field of electron paramagnetic reso-

nance. The idea of the Award was suggested by Pro-

fessor K.  M.  Salikhov, head of the Kazan Physical-Tech-

nical Institute. The Zavoisky Award is presented every

year in September, in Kazan, celebrating birthday

anniversary of the EPR discoverer. Among the sci-

entists, who received the Zavoisky Award, there are

internationally recognized experts on EPR-spectros-

copy, such as William Mims, USA; Brebis Bleaney,

UK; Yakov Lebedev, Russia; Klaus Moebius, Germany;

James Norris, USA; James Hyde, USA; George Feyer,

USA; and Kamil Valiev, Russia.

E. M. PURCELL:

LIFE AND SCIENTIFIC JOURNEY

The obituary in the New York Times [30] paid

tribute to Edward M.  Purcell as a person “who made

it possible to “listen” to the whisperings of hydrogen

throughout the universe”, the fact of him sharing

the Nobel Prize in Physics “for discovering a way to

detect the extremely weak magnetism of the atomic

nucleus” made reference to in a later paragraph. (see

Fig.  10).

Best known for his two “fundamental discover-

ies” [31] – the discovery of NMR absorption and the

detection of the emission of radiation at 1421  MHz by

atomic hydrogen in the interstellar medium – each

leading “to an extraordinary range of developments”

in atomic, molecular and nuclear physics, chemistry,

medicine and radio astronomy, Purcell made “inge-

nious contributions” in biophysics and astronomy,

and “set a new standard of scholarship” in his Berk-

ley Course introductory textbook on electricity and

magnetism.

Anatole Abragam, a Russian born French physi-

cist held in high regard by his Soviet colleagues, who

knew Purcell well, greatly appreciated his personality

and professionalism. He wrote [32]: “As a physicist

and a human being Ed Purcell is perhaps the man

I admire the most. I have never met anyone more

profoundly authentic, more detached from the wish

to appear other than he is.”

In his autobiography [32] he compared Purcell to

Andrey Sakharov. Once you remember how in 1965

he resigned from the President ’s Science Advisory

Committee in protest against the continuing war in

Vietnam, this parallel between the two great men

comes out ever more convincing.

Below is a brief account of the life and scientif-

ic path of Edward Purcell, an outstanding scientist,

an indefatigable researcher, a brilliant teacher and a

visionary, any scientific project was lucky to have at

its team. Facts of his life and his personal attitudes

have been preserved for future generations in his

interviews and in reminiscences of his close associ-

ates (for example, [31]), courtesy of the efforts from

his colleagues at the American Institute of Physics,

the Institute of Electrical and Electronics Engineers,

the Harvard University, the Perdue University, the

American Philosophical Society, the Nobel Founda-

tion archives, the Niels Bohr Library and Archives,

and other institutions, like in [33-35]. In Russian, the

most detailed biographical account of E. Purcell and

F. Bloch was given by N.  E.  Zavoiskaya [26].

Fortune seemed to favor E.  M.  Purcell through-

out his entire life. He was born in a small Ameri-

can town of Taylorville, Illinois, some two hundred

miles southeast of Chicago, in a Presbyterian family.

His mother, Elizabeth, taught Latin in a high school

in Taylorville. His father, also Edward, was manager

Fig.  10. E.  M.  Purcell. Source: The Free Encyclopedia; URL:

https://en.wikipedia.org/wiki/Edward_Mills_Purcell.

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BIOCHEMISTRY (Moscow) Vol. 90 Suppl. 2 2025

of the local telephone company. Hence, for his son

the discarded electronic equipment and periodic is-

sues of scientific journals, like the Bell System Tech-

nical Journal, were part of his everyday life. When

in high school, his family had moved to Mattoon,

Illinois – a bigger town closer to Chicago, where

Edward, together with his equally enthusiastic school

friend, took an interest in chemical experiments. His

chemistry teacher was a great influence on him – as

Purcell himself reminisced, “it was the first time I

had encountered any grownup who was a real sci-

entist” [35]. The woman who taught him physics

was not that much versed in her subject, but she re-

spected it and fostered that respect in her students.

“She introduced me to physics in a humane way that

probably was important”, – he said in one of the

interviews [35].

As Purcell himself recounted [35], for him, a high

school graduate in late 1920s, the name of Steinmetz,

a famous electrical engineer, was “more familiar and

exciting than the name Einstein”. Edward entered the

Perdue University, Indiana, to study electrical engi-

neering. His aptitude for research did not go unno-

ticed and eventually he studied under the tutelage

of Karl Lark-Horovitz (1892-1958, an Austrian immi-

grant), the man who brought the Perdue University

to prominence. In 1933, after he had graduated from

Perdue University with the degree of Bachelor of Sci-

ence in Electrical Engineering, Purcell was awarded

an exchange fellowship in Europe, in Germany to

be precise, at the time the world’s most important

center for physics – namely, he went to Technische

Hochschule in Karlsruhe (Karlsruhe Institute of Tech-

nology, now part of the University of Karlsruhe).

Unfortunately, it was the very time when the Nazi

Party was rising to power, a political development to

which academic life was not immune either. Profes-

sor Walter  Weizel (1901-1982), a theoretical physicist

whose lectures on physics Purcell attended, for exam-

ple, was forced to temporarily leave the Institute for

his anti-Nazi views. As an exchange student, Purcell

spent in Karlsruhe one year, and, despite the disturb-

ing political circumstances, it happened to be a lucky

turning point in his life. On his way to Germany Ed-

ward met another exchange student, Beth  C.  Busser.

She was going to Munich to study German literature.

Although Busser had little to no interest in physics,

she accompanied Purcell to the lectures given by the

distinguished physicist Arnold  Sommerfeld in Mu-

nich – she helped take notes. Four years later, not

long before Purcell earned his PhD, they got married,

for life. Edward and Beth had been together for 60

years and raised two sons.

On his return to the United States, in 1934, Purcell

won a scholarship to Harvard and joined the Depart-

ment of Physics as a graduate student, with the sup-

port of Lark-Horovitz. There, at first, he was involved

in electron diffraction studies of thin films to later

embark on other research projects (including his in-

vestigation of magnetic properties of salts at liquid

helium temperatures [36]). One of his projects, the

study of the focusing properties of charged parti-

cles in a spherical condenser, provided him with his

dissertation and his Doctor of Philosophy degree in

1938. Purcell was also on the team constructing the

first Harvard cyclotron. He helped to build a magnet

for it [34].

Throughout the World War II Purcell worked

at the Radiation Laboratory established at the Mas-

sachusetts Institute of Technology in the autumn of

1940. There he joined a team of American and British

physicists entrusted with developing a military micro-

wave radar technology. The Rad Lab was a gigantic

institution employing up to 3500 people at its peak in

1945. By the end of the war the innovative designs

developed by its scientists resulted in mass radar

production. It looks like some of the equipment was

supplied to the Soviet Union under the Lend-Lease

Act for military purposes. The series of books, com-

missioned by the Laboratory to preserve the tech-

nology developed within its walls and to the writing

of which Purcell and his NMR apparatus co-authors

contributed, included, according to N.  E.  Zavoiskaya,

28 volumes! Some of these books were translated into

Russian and were in wide circulation among the Sovi-

et laboratories researching ultra-high frequencies and

radar technology.

In his Radiation Laboratory years Purcell worked

directly with Isidor  I.  Rabi, associate director of the

Laboratory and father of the experimental magnetic

resonance method, as well as with some other phys-

icists, who partook in the first magnetic resonance

research. With this in mind, it comes as no surprise

that after the war was over, since the autumn of 1945

up till 1954, Purcell and his close associates had been

directing their major efforts to the development of

NMR theory and methods (more on this in “The Part

E.  K.  Zavoisky, E.  M.  Purcell, and F.  Bloch Each Played

in the Development of Magnetic Resonance Theory,

Methods, and Applications” Section). In those same

years he carried out other equally groundbreak-

ing research. The last century can undoubtedly be

dubbed as “the Century of Radio Physics”, among

its other history-inspired names. Midway through

the century were the years when radio instrumen-

tation was taken by its designers to the new level of

sensitivity, horizons for its application dramatically

broadened. NMR was a new development in radio

spectroscopy, but Purcell made a major contribution

to yet another field of science – to radio astronomy.

Together with Harold Ewen (see Fig.  11), his PhD stu-

dent, Purcell was the first to detect radio emission

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BIOCHEMISTRY (Moscow) Vol. 90 Suppl. 2 2025

Fig.  11. Horn antenna used by Harold  I.  Ewen and

Edward  M.  Purcell at Harvard University in 1951. Source:

The Free Encyclopedia; URL: https://en.wikipedia.org/wiki/

Edward_Mills_Purcell.

from the neutral atomic hydrogen gas in the Milky

Way, also referred to as the 21-centimeter radiation,

with a horn antenna placed at the top of one of the

Harvard’s buildings [37].

Average interstellar atomic gas density is less

than 1 atom per cm

. The bulk of gas is contained

in a layer of several hundred parsec at a close dis-

tance from the galactic plane. The gas density aver-

ages around 10 to 21  kg/m

. The idea of hydrogen

atoms presents in the interstellar medium and thus

of the possibility of radiation at the frequency of

1420  MHz (λ  ≈  21  cm) had already been discussed by

astronomers for several years before the experiment.

I.  S.  Shklovsky, a Soviet astrophysicist, for example,

back in 1948, performed detailed calculations for the

neutral hydrogen line, predicted by H.  C.  van  de  Hulst

(the Netherlands) in 1944, and demonstrated, that the

intensity of galactic radio-frequency radiation within

this line was high enough to be detected with the

equipment available at the time.

This radiation is emitted when a transition oc-

curs in an H-atom between the energy levels of anti-

parallel magnetic moments of a proton and an elec-

tron, induced by Fermi interactions of the F = AIS

type, where I,S are spin operators of the proton and

the electron, respectively. This interaction, originating

from the collision between an electron occupying an

s-orbital and a proton, had been predicted by Enrico

Fermi [38] with the use of the Dirac equation, years

before the Ewen–Purcell discovery. For its compara-

tively small magnitude (if compared to both Coulomb

interaction and to “fine” spin-orbital interactions) this

interaction is called ‘hyperfine’, and for its nature it

is called ‘contact’. When no external magnetic field

is applied, the energy 2πħA equals the difference be-

tween the triplet state energy (parallel spin pairing)

and the singlet state energy (antiparallel spin pair-

ing). Observing radiation from the interstellar clouds

of atomic hydrogen makes it possible to estimate

their density as well as presence or otherwise of in-

terplanetary dust clouds in the space between them

and the Earth, among other things. Later on, Purcell

took part in a number of other astrophysical (radio

astronomical) research projects [39-41].

Early in 1950s another original work was pub-

lished, in which Purcell and S.  J.  Smith discovered

emission of visible light by a relativistic electron

beam sent close to the surface of a diffraction grat-

ing. In some respect, this radiation is comparable to

Vavilov–Cherenkov radiation. Interestingly, Purcell,

apparently, holds no patent relating to either NMR

methods or the Smith–Purcell radiation (as it is now

often referred to, as in [42]), while others, with Pur-

cell mentioned and not, took patents on inventions in

both those fields. For example, a U.S. patent on the

microwave generator using the Smith–Purcell effect

was granted to C.  A.  Ekhdal in 1986 (application filed

in 1983), the work by Smith and Purcell [43] referred

to in the application. The U.S. patent of F.  Bloch and

W.  W.  Hansen on NMR chemical uses, purchased by

Varian Associates, is discussed in the last section of

this work.

In 1950s Purcell also participated in the research

project investigating radio propagation at very high

frequencies observable over long distances by means

of inhomogeneities in the ionosphere (the team was

comprised of eight co-authors from four institutions

including the U.S.  National Bureau of Standards, the

Harvard University, etc. [44]). He also was a part of

the team that proved, with high precision, the hy-

pothesis of elementary particles and nuclei having

no electric dipole moments (together with Norman

Ramsey, Jr. [45]).

In 1949, Purcell became Professor of Physics at

Harvard, one of the most respected Departments at

the University and in the U.S in general, one may say.

He wrote a textbook on electricity and magnetism

[46], which was published in 1965 and became Vol-

ume  II of the Berkley Physics Series (second edition

in 1985) (Fig.  12). To the present day this textbook

is considered to be one of the most up-to-date phys-

ics courses. In the second edition, published in 1985,

DISCOVERERS OF MAGNETIC RESONANCE IN MATTER S419

BIOCHEMISTRY (Moscow) Vol. 90 Suppl. 2 2025

Fig.  12. Collage of volumes of the Soviet edition (1971) of the Berkeley Physics Course, including Vol.  2 (Electricity and

Magnetism) by Purcell  [46]. A page of the journal with semi-humorous illustration of E.  M.  Purcell to his paper “Life at Low

Reynolds Number”  [51] can be seen at the background. Source: V.  V.  Ptushenko’s personal archive.

Purcell, retaining his preferred Gaussian units, in-

cluded alternative versions of the equations in Sys-

tème International (SI), thus harmonizing the use of

different systems of measurement in the courses of

general physics and electrodynamics of continuous

media. Purcell’s textbook is instrumental in analyzing

the differences in using H and B in the formula no-

tations for magnetic resonance effects (and for other

magnetic field phenomena) [47].

In 1962, Purcell joined yet another attempt

at finding Dirac monopoles – this time the search

was for magnetic monopoles produced in collisions

of the 30-BeV protons with different targets at the

Brookhaven alternating gradient synchrotron. The

result was a negative solution for the collisions of

protons with heavy nuclei [48], with an accuracy of

−40

cross sections. This problem – set by Dirac

with many unknowns, like the said monopole mass

and magnetic charge – added a negative experiment

outcome to the Purcell’s otherwise brilliant track re-

cord of solving scientific enigma. As A.  Abragam re-

marked on this episode in his career: “the best hunt-

er comes home with an empty bag if the game is

not there”.

In 1967, Purcell took an interest in some biophys-

ical problems, namely in those relating to biomechan-

ics: his collaboration with H.  C.  Berg, a Harvard bio-

physicist, resulted in the U.S. patent for an elegant

particle separator [49] and a number of publications

[50]. In 1967 the American Journal of Physics reprinted

his talk intriguingly titled “Life at Low Reynolds Num-

ber” with the figures reproducing the transparencies

used by Purcell in the original talk and made by his

hand [51] (Fig.  12). The paper described locomotion of

E.  coli bacteria in water. In the same very 1977, with

the above-mentioned Howard Berg, Purcell published

a joint paper on bacterial chemoreception [52].

In 1970 Purcell became the President of the

American Physical Society. Up till 1980 he was teach-

ing at the University, and in 1980s he was a regular

pedagogical contributor to the American Journal of

Physics, including writing an educational column un-

der the name “Back of the Envelope” ([53] and other

issues).

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BIOCHEMISTRY (Moscow) Vol. 90 Suppl. 2 2025

FELIX BLOCH:

BIOGRAPHICAL ACCOUNT

Felix Bloch (Oct.  23,  1905-Sep.  10,  1983), a historic

figure in the 20th century physics, who shared the

1952 Nobel Prize for Physics with Edward Purcell,

was born in Zurich, Switzerland, to a family of

Gustav Bloch, a wholesale grain dealer, and Agnes

Bloch (née Mayer). A concise but detailed account of

his life is available at the Nobel Foundation archive

[54] (see Fig. 13). Among the many materials devoted

to his life and work and available across the Internet,

the interviews he gave in person and his colleagues’

memoirs stand out [55-57].

Felix Bloch attended a gymnasium run by the

Canton of Zurich, which he graduated in 1924. With

mathematics and astronomy taking his particular in-

terest, he (like E.  M.  Purcell) chose engineering as his

future profession and entered the Federal Institute of

Technology (Eidgenössische Technische Hochschule) in

Zurich. One year into his studies, though, he changed

from engineering to physics having made a decision

to become a theoretical physicist instead. Between the

years of 1924-1927 he studied at the Federal Institute

of Technology, Perter Debye and Erwin Schrödinger

among his teachers. In 1928, Bloch defended his dis-

sertation and earned his Doctor of Philosophy Degree

at the University of Leipzig under the direction of

Werner Heisenberg, who suggested that he should

dedicate his thesis to the study of conductivity of

metals by applying the quantum mechanical theory.

Significance of this paper cannot be overstated, for in

it Bloch provided the basis for a number of fields in

solid state physics by formulating a theorem for the

electron wave functions in metals (Bloch function or

Bloch waves or Bloch state).

In the years following publication of his doctoral

thesis, Bloch held a number of assistantships and fel-

lowships, through which he worked with Heisenberg,

Bohr, Fermi, and Pauli. That was the time when he

made arguably his biggest contribution to theoretical

physics. Bloch gave a theoretical justification for the

empirical Grüneisen’s rule connecting conductivity

of metals to temperature – nowadays it is known as

the Bloch–Grüneisen relation. More than several the-

orems and phenomena bear the name of Felix Bloch

following his contribution to the theory of supercon-

ductivity and his theoretical treatment of magnetic

systems. Among them are: the Bloch’s theorem in the

theory of superconductivity; the Bloch’s T

3/2

law for

temperature dependence of magnetization; the Bloch

walls (a transition region between two domains in a

ferromagnetic material with antiparallel spontaneous

magnetization alignment). In 1932, he developed fur-

ther the ideas of Niels Bohr and Hans Bethe on the

stopping power of charged particles in matter and, as

a result, obtained the famous Bethe–Bloch formula.

Most of the outstanding papers mentioned here he

worked on and published in Germany.

When, in 1933, Hitler came to power in Germa-

ny, Bloch, a Jew by birth, left the country to never

return. He spent some time in Europe– Zurich, Paris,

Copenhagen, Utrecht, and Rome – giving lectures and

continuing his scientific work. Among his options for

a secure place to work from then on, he considered

the Soviet Union as well. Through his work with

W.  E.  Pauli, Bloch knew L.  D.  Landau in person and,

in 1931, upon Landau’s invitation, he visited Lenin-

grad. He was also personally acquainted with another

Soviet physicist, Y.  G.  Dorfman. There are three let-

ters Bloch wrote to Dorfman, all three now kept at

the museum of St. Petersburg Polytechnic University,

from which it is clear that he considered accepting a

position at the nascent Ural Institute of Physics and

Technology offered to him by Dorfman (for more on

this see N.  E.  Zavoiskaya’s book [26]).

Bloch understood all too well how fragile was the

situation in Europe in the face of the rising Nazism,

as he understood the dangers of being a foreigner in

the Soviet Russia. So, in 1934 he left Europe for the

United States, where, as a “displaced German schol-

ar”, he was offered a position at Stanford University

[56]. In 1939, he became a naturalized citizen of the

United States. In 1940, Felix Bloch married Lore  C.

Misch, another physicist, who had also fled Germany;

they had three sons and a daughter.

He joined Stanford as acting associate professor

of physics to become full professor two years later.

In that period Bloch published a number of import-

ant research papers treating problems relating to

the quantum theory of electromagnetic field. Then

he took an interest in the newly discovered neutron,

his research leading him to the assumption that its

Fig.  13. Felix Bloch. Source: The Free Encyclopedia; URL:

https://en.wikipedia.org/wiki/Felix_Bloch.

DISCOVERERS OF MAGNETIC RESONANCE IN MATTER S421

BIOCHEMISTRY (Moscow) Vol. 90 Suppl. 2 2025

magnetic moment could be determined by scattering

of slow neutrons in the magnetized matter and that

the scattering could result in a beam of polarized

neutrons. Next year validity of his hypothesis was

confirmed. Following his interest in physics of neu-

tron interactions, Bloch turned to the experimental

research. In 1930s I.  I.  Rabi developed his molecu-

lar beam resonance method of measuring magnetic

moments of nuclei. In 1939, together with Luis  W.

Alvarez, Bloch experimentally measured magnetic

moment of a neutron with the magnetic resonance

method similar to the one employed by Rabi. To pro-

duce neutron beams they used the 37-inch cyclotron

at the University of California, Berkeley [58]. In 1940,

together with Arnold Siegert, he published a paper

suggesting an approximation procedure for calcu-

lating magnetic resonance frequency in the linearly

polarized magnetic field [59]

, which proved to

be of high significance for the magnetic resonance

method.

Unlike E.  M. Purcell or E.  K.  Zavoisky, Bloch thus

began his investigations into magnetic resonance in

condensed matter armed with some prior experi-

ence with magnetic resonance phenomena. During

the World War II Bloch was invited to Los Alamos

to join the Manhattan Project team, where, for some

time, he was researching properties of uranium iso-

topes. Later, he joined the Radio Research Laboratory,

established at Harvard University to develop counter-

measures to radar, as an associate group leader in

the theoretical division.

When the war was over, shortly after he re-

turned to Stanford University, Bloch embarked upon

the studies of atomic nuclei (protons) magnetic res-

onance, in which radio wave technology, obviously,

was employed. For physicists to investigate behavior

magnetic moments in atomic nuclei of various types

of nuclei they needed to be obtained with high accu-

racy. To make this possible, Bloch, in 1946, suggested

using an original nuclear induction method (for more

on this see “The Part E.  K.  Zavoisky, E.  M.  Purcell, and

F.  Bloch Each Played in the Development of Magnetic

Resonance Theory, Methods, and Applications” Sec-

tion). Felix Bloch is renowned for a great many con-

tributions to the advances of physics, but it was the

nuclear induction method he was awarded the Nobel

Prize for.

After 1946, Bloch devoted most of his time to ex-

perimental and theoretical research of NMR (“nuclear

induction”) (more on this later). In 1954-1955 he took

a two-year sabbatical leave to assume a position of

Director General at CERN (the European Organization

for Nuclear Research, Geneva, Switzerland), the first

in its history. A.  Abragam vividly described the CERN

period of the Bloch’s life in his book [32]. Suffice it to

say, Bloch, according to Abragam, “accepted his posi-

tion out of good will towards old Europe”, “disliked

the “Big Science”

and hated administration”.

In the fall of 1955 Bloch resigned his position in

CERN and returned to Stanford. In 1971, after his res-

ignation from Stanford, Bloch came back to Zurich,

where he passed away on September  10, 1983. Felix

Bloch was elected to the American National Academy

of Science, American Academy of Arts and Sciences,

Royal Netherlands Academy of Arts and Sciences,

Swiss Physical Society, and the American Physical So-

ciety of which he was President in 1965.

THE PART E. K.ZAVOISKY,

E. M.PURCELL, ANDF.BLOCH

EACH PLAYED INTHEDEVELOPMENT

OFMAGNETIC RESONANCE THEORY,

METHODS, ANDAPPLICATIONS

The problem of resonance radiation detected

when a transition occurs between the energy lev-

els of magnetic moments differently oriented in the

external field was first posed by P.  Ehrenfest and

A.  Einstein [60]. O.  Stern’s et  al. [61], through experi-

mentation, determined the hydrogen molecule’s pro-

ton spin orientation in a magnetic field, a discovery

that won him the 1943 Nobel Prize for “his discovery

of the magnetic moment of the proton”

. Very per-

sistent in his search for nuclear magnetic resonance,

although much less lucky, was C.  J.  Gorter (Fig.  14).

In his first attempt [7] to observe the phenomenon

with the use of calorimetric method for measuring

energy absorption, he failed. In the same year, though,

Gorter and his team detected absorption and disper-

sion phenomena in a specimen exhibiting paramag-

netism induced by an applied external magnetic field

(see, for example, [8]). They thus demonstrated that

the energy absorption and dispersion was a function

As is commonly known, the simplest is the equation for a resonance frequency v

in an induced magnetic field B

specific (let us suppose, it is clockwise with γ  >  0) circular polarization of the resonance field applied: 2πv

 = γB

A linearly polarized field is the sum of two circularly polarized fields rotating in opposite directions. Unfortunately,

the Nobel Foundation archive biographical note [54] does not mention this paper [59] which resulted in another

phenomenon – changing of the above equation due to effect of the counter-rotating polarized field – taking Bloch’s

name (Bloch–Siegert effect or Bloch–Siegert shift).

Accelerators.

Full prize motivation reads as follows: “for his contribution to the development of the molecular ray method and his

discovery of the magnetic moment of the proton.”

KESSENIKH, PTUSHENKOS422

BIOCHEMISTRY (Moscow) Vol. 90 Suppl. 2 2025

of electromagnetic oscillations frequency, both im-

pacted by the intensity of magnetic dipole transitions,

also (resonance) frequency-dependent. However, for

some subjective reason (possibly, he considered elec-

tron magnetic resonance lines too broad, or the re-

quired range of accessible magnetic fields and fre-

quencies was not available), Gorter never tried to

detect electron paramagnetic resonance.

Not long after, I.  I.  Rabi and his group observed

nuclear magnetic resonance with his molecular beam

method [4] (Fig. 15). A couple years later, the same

group of physicists observed electron paramagnetic

resonance in atomic beams [62]. Finally, F.  Bloch and

L.  Alvarez determined magnetic moment of a neu-

tron by means of the cyclotron-produced polarized

neutron beam [58]. In all the three experiments res-

onance absorption was registered by particle detec-

tors, when particles, excited by magnetic resonance,

“jumped” from one orientation to another. All this

groundbreaking research prompted a string of dis-

coveries in the vast field of magnetic resonance phe-

nomena. Meeting particular conditions, though, was

a prerequisite for any specific line of investigation to

yield successful results.

In the same period (1940-1941), E.  K.  Zavoisky,

S.  A.  Altshuler, and B.  M.  Kozyrev had been perform-

ing their own experiments, in which they all but

succeeded in observing nuclear magnetic resonance

in matter. The Soviet physicists were the first to uti-

lize the radio physical methods to register resonant

absorption and dispersion induced by magnetic res-

onance. With a far more sensitive method at their

disposal, they were not discouraged by Gorter’s fail-

ure, and the advances made by Rabi’s group were in-

spiring. Zavoisky was determined to exploit potential

of the “grid current” method in scientific research to

the maximum [63]. In the years of 1935-1939 Evgeny

Konstantinovich published a series of papers, in all

of which he employed this method to study electro-

magnetic energy absorption in different substances

(electrolyte solutions, crystalline acids and salts, etc.).

None of the papers, though, demonstrated results of

particular interest or practical importance. Zavoisky

decided to use the “grid current” method in his mag-

netic resonance research. First promising results be-

gan to take shape. Tragic circumstances triggered by

the breakout of the World War II, though, put a stop

to his NMR experimentation (for details see [26, 47]

and other sources). To continue, he “only” needed to

get hold of another magnet or to update the one he

had at his disposal. At the very first opportunity – in

wartime Kazan it was equivalent to the slightest pos-

sible chance – Zavoisky returned to his magnetic res-

onance research, only this time he studied electron

paramagnetic resonance instead. Unlike C.  J.  Gorter,

pedantic but indecisive, Evgeny Konstantinovich

started straight away with investigating the media in

which EPR was expected to be observed, those with

the maximum or near maximum concentration of

paramagnetic electrons (third-row transition metal

salts and their concentrated solutions).

The reasoning behind his decision to move his fo-

cus to EPR instead of NMR is somewhat of a mystery

up to the present day. Indeed, Altshuler and Kozyrev

both mentioned, more than once, this change of focus

in their reminiscences: “In 1943, Evgeny Konstanti-

novich decided against continuing with NMR research

to embark on the studies of paramagnetic relaxation

for perpendicular fields instead… Meanwhile, it was

absolutely unclear why Evgeny Konstantinovich, who

came up with and performed the <…> modulation in

1943, made no attempts at observing NMR. It would

have been easier than to observe EPR. There was

no need to modify anything, all that needed to be

done was to place a vial with water inside a fully

functional apparatus. Apparently, Evgeny Konstan-

tinovich was fascinated by his EPR investigations

to the point when everything else was neglected”,

S.  A.  Altshuler shared with the audience of the First

Zavoisky Readings held at the Kazan University on

15 October, 1982 [27]. I.  I.  Silkin, founder and direc-

tor of the Museum-Laboratory of E.  K. Zavoisky at the

Kazan State University, believes there was no “change

of focus” per  se, rather his investigations were not

confined to NMR only and he searched for a signal

within a wide range of parameters (I.  I.  Silkin, a per-

sonal message). His judgment is supported by the re-

cords in the Zavoisky’s laboratory notebook for the

period of late 1943-early 1944, in which, along with

studying paramagnetic losses for paramagnetic spe-

cies, he frequently mentioned planning to do experi-

mental research “pertaining to the expected nuclear

spin resonance”, as well as drew tables of resonance

wavelength values for different nuclei he calculat-

ed, etc. (excerpts from the laboratory notebook were

published by Silkin in his book [9]). At the same time,

according to S.  A.  Altshuler [27], “In 1946, Purcell and

Bloch published their papers, both announcing they

observed NMR. I was there when Evgeny Konstanti-

novich looked through the papers. He was not disap-

pointed. On the contrary, he was glad the apparatuses

were largely the same as his. He considered those

papers a continuation and development of his EPR

research.”

There is a Latin proverb “Fortune favors thebold”.

Early in 1944, Zavoisky observed EPR in the frequency

range between 10 to 100  MHz and higher in the fields

produced by means of solenoids with no iron core

and providing for magnetic induction ranging from 3

to 30  G (that is 3·10

−4

to 3·10

−3

  T). High concentration

of paramagnetic electrons did not result in excessive

broadening of the EPR line (an outcome Gorter had

DISCOVERERS OF MAGNETIC RESONANCE IN MATTER S423

BIOCHEMISTRY (Moscow) Vol. 90 Suppl. 2 2025

Fig.  14. S.  A.  Altshuler, C.  J.  Gorter, C.  D.  Jeffries, Kazan, USSR, 1969. Source: N.  E.  Zavoiskaya’s personal archive.

Fig.  15. E.  Lawrence, E.  Fermi, I.  Rabi, Los Alamos, US, 1942-1943. Source: The Free Encyclopedia; URL: https://en.wikipedia.

org/wiki/Isidor_Isaac_Rabi.

KESSENIKH, PTUSHENKOS424

BIOCHEMISTRY (Moscow) Vol. 90 Suppl. 2 2025

presumably expected), quite the opposite – due to

the so-called exchange narrowing, determined later

by Van  Vleck, it caused the EPR line to slim down

in the center, its wings though still broadened. Some

simple paramagnetic substances – transition-element

salts– turned out to be the easiest to observe EPR in.

The discovery of such a fine physical phenome-

non in Kazan, severely understaffed and in desper-

ate need of equipment and financing, baffled sci-

entific minds of the Physical Institute of the USSR

Academy of Sciences to the point of skepticism. Any

doubts were dispelled though when A.  I.  Shalnikov

reproduced the Zavoisky’s experiment at the Institute

for Physical Problems and validated the discovery.

N.  E.  Zavoiskaya in her book [26] recounts the events

surrounding the breakthrough experimentation in de-

tail. His first paper announcing the discovery of EPR

in English Zavoisky published with a delay, but still

six months before Purcell and Bloch each published

theirs. It may not have had any influence on the tra-

jectory of the American physicists’ NMR research

Both Nobel Prize winners-to-be had been ready at

the starting line, if an analogy can be drawn between

science and high-performance sport with its nev-

er-ending competition to be pronounced the first, the

best, the strongest. This was not, however, the point.

Purcell and Bloch had both been working at the

world’s best radio research laboratories for some

five years immediately before they engaged in their

respective NMR investigations. Radio equipment was

thus their clear choice for observing the phenome-

non of interest. Purcell mentioned that early on in

his quest for NMR he heard of the second unsuc-

cessful attempt Gorter and Broer [64] made to detect

nuclear resonance – with the use of a radio appara-

tus (working largely according to the same principle

as the apparatus Zavoisky built for his experiment).

R.  V.  Pound, one of Purcell’s co-authors in his first

fruitful NMR experiment, and W.  D.  Knight [65] later

successfully employed this principle (a marginal os-

cillator with a sample contained in a cylindrical coil)

to quickly detect intense and not too narrow reso-

nances.

Gorter’s bad luck with NMR was largely due

to his unfortunate choice of substances (diamagnet-

ic crystalline salts) and conditions (low tempera-

tures) for the experiment

. But Purcell (a student

of J.  Van  Vleck and I.  Rabi) and Bloch (a student of

P.  Debye, close acquaintance of Van  Vleck and an ex-

pert in the theory of solids) were not meant to make

the same mistake – they both were aware of the

nature of spin–“lattice” (molecular oscillations and

movement) interaction.

The moral of the story: discovery of magnet-

ic resonance was not a one and done process. The

relation between resonance frequency and magnetic

induction v

 = (γ/2π)B

(the resonance condition; note

that in the first papers on NMR, for the resonance

condition, H notation was used instead of B, because

in the Gaussian unit system then in use, in vacuum,

induction as measured in Gauss was equal to mag-

netic field intensity as measured in Oersted. On top

of this, according to H.  Kopfermann [66], G.  Mie and

A.  Sommerfeld both used H, not B, as a notation for

induction; see also [47]) was, by 1945, known for pro-

ton, electron, and several more nuclides (at least ap-

proximately). As was well known that, at resonance

frequency, magnetic induction of the alternating field

must be perpendicular to magnetic induction of the

polarization field. What else was there to be discov-

ered? At times, gyromagnetic ratio γ for a particular

nuclide NMR was to be determined (measured), that

is, in modern terminology, EPR g = γ/2πβ, in which

β is a Bohr magneton, for a particular molecular

or nuclear system containing an unpaired electron.

At times, signal power or excitation process was to

be chosen, according to the spin–lattice interaction

conditions. In a word, magnetic resonance, deter-

mined by Rabi experimentally, had to be observed

again and again in totally different circumstances, or

re-discovered all over again for every new object if

you will. Interaction between the paramagnetic sub-

stances with high electron concentrations and res-

onance field (EPR for transition element salts) was

discovered by Zavoisky. EPR of minor transition el-

ement impurities in the diamagnetic crystals, within

a wide temperature range, was first studied by the

group of B.  Bleaney at Oxford [67]. EPR of the sta-

ble free radicals was first observed by B.  M.  Kozyrev

and S.  G.  Salikhov [68], Zavoisky’s collaborators. Their

research narrowly escaped being stamped classified

and thus, unfortunately, it was published later, when

similar papers by their colleagues in the West had

already been released. In 1949, EPR in the crystals

colored by irradiation was observed for the first time

[69], etc.

An altogether different story unfolded with re-

spect to observing nuclear resonance – that is, NMR

But it definitely had an influence on and de facto facilitated research on EPR resulting in the first papers on the

subject to be published a year later.

To observe NMR, the difference in population between the magnetic spin levels must not equalize too quickly by

transitions induced by magnetic field at resonance frequency, that is the resonance must not be saturated. To avoid

saturation there must be quite intense interaction between the spins and lattice oscillations or molecular movement.

Such interaction intensifies, when there are paramagnetic impurities present, temperature somewhat increased.

DISCOVERERS OF MAGNETIC RESONANCE IN MATTER S425

BIOCHEMISTRY (Moscow) Vol. 90 Suppl. 2 2025

in diamagnetic substances. The latter included gases,

liquids, glasses, crystals, etc., conditions for the spin–

lattice or spin–spin interactions different in every

case. Analysis of the papers published immediate-

ly after NMR was first observed clearly shows that

Purcell, much like Zavoisky, was driven by the am-

bition to maximize the use of radio equipment, its

capabilities unprecedented for the time in scientific

research. A modest set of radio apparatus Zavoisky

had in 1940s paled in comparison to what Purcell,

Torrey, and Pound had at their disposal. Design of the

apparatus E.  M.  Purcell, H.  C.  Torrey, and R.  V.  Pound

[15] chose for their NMR experimentation was simi-

lar to that of radar equipment in its radio-frequency

part, only it was adjusted for a different frequency

range (30  MHz or λ  =  10  m). That is, they placed the

sample (over 750  g of paraffin) in an inductive part

of a resonant cavity loaded by the capacity, instead

of simply putting it within a coil.

The subjects of the earliest papers on nuclear

magnetic resonance co-authored by Purcell are inter-

esting to pay attention to. First, he detected nucle-

ar magnetic resonance for protons in paraffin [15].

It was followed by the NMR for protons observed in

hydrogen gas [70]. Then, he investigated anisotropy

of NMR properties for fluorine

F nuclei in a sin-

gle crystal of CaF

[71]. Three years later a paper on

NMR in rigid crystal lattices was published, which in-

troduced the phenomenon of NMR second moments

to practical spectroscopy [72]. Finally, nuclear mag-

netic resonance in solid hydrogen was studied [73].

Numerous times Purcell shifted his focus to the

study of NMR phenomenon specific properties and

the nature of interactions between the magnetic mo-

ment system and an apparatus or a substance (the

lattice). Such “digressions” led to publication of a

number of papers. Among them are: the paper by

Purcell and Pound on the nuclear spin system at

negative temperature [74], and the famous BPP pa-

per – the paper by Bloembergen, Purcell, and Pound

on relaxation effects in liquids containing hydrogen

[75]. The latter for many years had been a classic of

practical spectroscopy of liquid solutions for analyz-

ing line broadening and saturation effects pertaining

to NMR. The paper on NMR line shapes, by Pake and

Purcell [76], had a profound effect on the terminolo-

gy now in use in NMR spectroscopy. In particular, it

set the stage for modern line shape functions clas-

sification (in “zero approximation” – Lorentzian and

Gaussian line shapes).

Among the Purcell’s works, which had an impact

on physics in general, his paper on spontaneous emis-

sion probabilities at radio frequencies, induced by the

interaction between a magnetic moment system and

a resonant electrical circuit [77] with a high Q factor

stands out. From the Einstein relation, the probabil-

ity of a spontaneous emission A

from an oscillator

system at frequency v is proportional to v

(that is to

the number of radiation oscillators per unit volume

8πv

multiplied by the energy hv of the oscillator).

However, in a resonator of volume V and quality fac-

tor Q, the first of the factors increases (3λ

/4π)(Q/V )

times, where λ is the wavelength. Purcell presented

this paper at the meeting of the American Physical

Society immediately after he had observed NMR for

the first time. Spontaneous emission effects, detected

when a polaron interacts with a resonant structure

in crystals, is now also referred to as the Purcell ef-

fect [78].

In 1949, Purcell published an important metro-

logical research paper on determination of the proton

magnetic moment in Bohr magnetons [79], to which

end he compared the diamagnetic (cyclotron) reso-

nance frequency to that of the proton magnetic reso-

nance in one and the same magnetic field.

Together with Herman Carr, he published an

outstanding, methodical work [80], which, in many

respects, anticipated the multiple-pulse sequence

technique for NMR excitation (“spin choreography” –

the term R. Freeman coined for the method in his

book [81).

Pulse sequences designed in a specific way are

now widely used in chemistry in multidimensional

NMR spectroscopy (e.g., Ernst et al. [82]) and in NMR

imaging [83, 84].

From this Carr–Purcell research stemmed the

method of measuring molecular diffusion coefficient

in liquids by multiple excitation pulses applied to an

inhomogeneous polarization field.

It also laid foundation for the development of

the DOSY (Diffusion Ordered SpectroscopY) method.

With this method, signals in the NMR spectrum are

differentiated according to molecular weight by sep-

arating large (slowly diffusing) molecules from small

molecules. The latter are faster diffusing in the re-

gion of the sample with different values for polar-

ization field induction and resonance frequency, and

produce quickly decaying signals.

For Felix Bloch, the leader of the Stanford

group of NMR explorers (F.  Bloch, W.  Hanses, and

M.  Packard), inspiration came, we believe, from two

sources. Firstly, it was his prior experience with

magnetic resonance [58,  59]. Secondly, according to

H.  Staub, one of Bloch’s co-authors, it was his inter-

est in the magnetic properties of a neutron (for the

quotation from H.  Staub see [26]). To observe proton

magnetic resonance, Bloch and his group used an

original apparatus. Its receiver coil was arranged per-

pendicular to the transmitter coil (Bloch’s crossed-coil

arrangement – pretty much everything he touched

was eventually named after him!). Given the electro-

magnetic signal transmitted by the excitation coil was

KESSENIKH, PTUSHENKOS426

BIOCHEMISTRY (Moscow) Vol. 90 Suppl. 2 2025

“steered” to the receiver coil (by means of semicircu-

lar copper “paddles”) before the resonance occurred,

it could only be precession of the proton magnetic

moment in the sample that led the signal off to the

receiver to be measured. He gave this phenomenon

the name of magnetic induction, thus echoing the pa-

per he co-authored with A.  Siegert [59], in which mag-

netic resonance excited under the action of rotating

and linearly polarized fields was considered. Bloch

developed a simple but efficient theoretical appara-

tus [85] that phenomenologically described magnetic

resonance for a magnetic moment in a macroscopic

sample. The vector differential equation or, respec-

tively, the three linear differential equations for each

of the components of a magnetic moment, were im-

mediately termed (obviously!) the Bloch equations.

It took some time for the inventors of the two

different NMR excitation methods to realize that

both were similar in that the phase balance or en-

ergy balance was registered by a specific part of the

apparatus, although they did vary in their technical

execution. The balance is changed by the nuclear

magnetic resonance signal, and the Bloch equations

are applicable (more often in liquids, as demonstrat-

ed by Bloch’s further investigations) or inapplicable

(according to the nature of the substance NMR is ob-

served in) independent on the method used to ex-

cite or receive the signal. In zero approximation, the

Bloch equations describe behavior of the magnetic

moment in basically any substance.

Bloch did not hesitate to use his method to per-

form another series of measurements to determine

the magnetic moment of a neutron, including in its

free state, with higher precision. Next, by means of

the nuclear induction method, the magnetic moment

of deuteron was determined [86] with that of tritium

(a heavy isotope of hydrogen, its nucleus containing

two neutrons and a proton) to follow suit a year

later [87].

Finally, on his initiative, Larmor precession fre-

quencies for neutrons and protons were determined

in the same magnetic field [88]. Thus, Bloch followed

through with his plan he shared in the early months

upon his return to Stanford.

Nuclear relaxation in gases resulting from nuclei

interaction with paramagnetic centers on the surface

of a container filled with gas was studied in a stand-

alone paper [89]. According to Bloch, in gases (as in

liquids), paramagnetic centers act as a catalyst in or-

der to obtain sufficiently short relaxation times for

the establishment of thermal equilibrium. His last

experimental research in the field [90] proved to be

instrumental to the development of NMR equipment.

In this last experimental paper, Bloch proposed quick-

ly rotating the specimen

to eliminate the influence

of the magnetic induction azimuthal inhomogeneity

on the observable NMR line broadening. This method

soon became firmly established in the high-resolution

NMR laboratory practice. At the time, it increased re-

solving power of spectrometers almost ten times.

After 1952, Felix Bloch returned to his theoreti-

cal investigations. He concentrated on the treatment

of the equations now bearing his name, the Bloch

equations, assessing their applicability from the view-

point of statistical physics [91, 92]. Anatole Abragam,

who later integrated the key ideas presented in those

works into The Principles of Nuclear Magnetism [93] –

the Bible as this volume was sometimes referred

to [32] – described his reaction in such a way [32]:

“When he asked for my opinion of it, I replied

in one word: ‘Wagnerian

’”.

In some of his later papers, Bloch treated prob-

lems relating to the quantum statistical theory as per-

taining to NMR as well [94, 95].

One of the Bloch’s co-discoverers of NMR (Wil-

liam Hansen, who died untimely in 1949) had close

ties with the Russell and Sigurd Varian brothers,

entrepreneurs highly competent and busy in the field

of electronics (Fig.16). Back in 1946, it was their idea

to apply for a patent on the “Method and Means for

Chemical Analysis by Nuclear Inductions” Accord-

ing to Weston Anderson, neither Bloch nor Hansen

showed any particular interest in pursuing the patent,

but Russel was persistent and took it upon himself to

file a US patent for them [96]. The patent was grant-

ed in 1951 with exclusive rights assigned to Varian

Associates, a family business of the said brothers. In

its first claim the final text of the patent covers all

magnetic resonances, EPR included. The story of this

patent Weston Anderson told for the Encyclopedia

of Nuclear Magnetic Resonance [96]. In his letter to

N.  E.  Zavoiskaya, dated 2003, R.  Pound also mentioned

that the text of the claim was later changed to include

EPR [26]. The stories told by Anderson and Pound

both speak to the fact that the claim was “edited” lat-

er to strengthen the company’s positions against other

market players, contending for similar inventions.

For over 15 years Varian Associates had been

the leader in NMR instrumentation development and

its investment in the patent, including royalty paid

to Bloch and Hansen, certainly paid off generously.

Nuclear magnetic resonance, instead of remaining

If the frequency of rotation v

rot

>> ( δ B ·γ), where δB is the maximum azimuthal inhomogeneity of the magnetic

field induction in the sample, the spectrometer registers a magnetic resonance frequency equal to the mean value

(it averages the frequency range and narrows the resonance line).

An allusion to the grandiose style of operas by Richard Wagner.

DISCOVERERS OF MAGNETIC RESONANCE IN MATTER S427

BIOCHEMISTRY (Moscow) Vol. 90 Suppl. 2 2025

Fig. 16. Brothers Russel (left) and Sigurd Varian (right).

Source: Sempervirens Fund, URL: https://sempervirens.org/

news/russell-varian-the-man-who-helped-win-the-battle-of-

britain-and-create-castle-rock-state-park/.

a “lonely idea”, as Loren Graham once put it [97],

yielded profits and provided for its own further de-

velopment. (For instance, the patent by W.  Anderson

and R. Ernst [98] underlying the transition from con-

tinuous-wave NMR to pulsed-gradient Fourier trans-

form NMR was based on the inventions made in the

laboratory of Varian Associates. Papers published by

other researches, though, gave Varian’s competitors

grounds for bypassing this patent as well.)

Up until the beginning of the 21st century, Varian

was the major player on the market of NMR instru-

mentation (till the 1980s, EPR instrumentation includ-

ed), in particular in its chemical analysis segment

(visionaries, aren’t they are!). Its closest competitor,

Bruker Corporation, originally a Swiss-German com-

pany Bruker–Physik AG, was established a decade lat-

er, but eventually grabbed the biggest market share.

The fact that Bruker–Physik AG and the like were

established and succeeded demonstrated that open

access research published by Purcell, Zavoisky and

other explorers of magnetic resonance phenomena

created loopholes for the Varian competitors to get

around the Bloch–Hansen patent.

Students of Purcell, outstanding scientists

N.  Bloembergen, H.  Carr, R.  Pound, G.  Pake, H.  Torrey,

all made significant contributions of their own to NMR

research. Among them, the most impressive strides,

albeit in another field, were made by N.  Bloembergen

(the Nobel Prize 1981 winner for the development

of laser spectroscopy). Their papers, with Purcell as

co-author, were referred to above. The famous Pake

Doublet – a characteristic NMR line shape seen in the

crystalline hydrates, which arises from dipolar cou-

pling between the two isolated protons in H

O – is

worth mentioning in this context as well [99].

Many of the Bloch’s collaborators continued

their research in the laboratory of Varian Associates.

Among them were Martin Packard, the youngest in

the group that observed NMR, and a successful re-

searcher and inventor Weston Anderson, who was

mentioned earlier in the context of the Bloch–Hansen

patent story. The Bloch equations were solved for the

case of rapid resonance passage by the theoretical

physicists R.  K.  Wangsness and B.  A.  Jacobsohn [100].

Later, Wangsness contributed to the quantum-statisti-

cal treatment of the Bloch equations [91].

Bloch and Purcell both had direct influence on

the development of NMR research in the USSR. The

first paper on NMR published in the Soviet Union,

by K.  V.  Vladimirskii, provided references to both

their works [101]. A collection of selected research

papers on NMR published by ‘Inostrannaya Literatu-

ra’ (Foreign Literature Press) in 1942-1950 served as

a reference book in the S.  D.  Gvozdover laboratory in

Moscow State University, for example

In 1950-1951, NMR found its application in a

number of Soviet Research and Development Centers,

like Laboratory #3 (now, the Institute for Theoreti-

cal and Experimental Physics of the Kurchatov Insti-

tute), Sukhumi Institute of Physics and Technology,

and Electrosila Power Engineering Plant in Leningrad

(more on this in [102]) immediately following its dis-

covery by Bloch and Purcell.

Acknowledgments

We are grateful to Natalya E. Zavoiskaya, Igor I. Silkin,

Tatyana I. Balakhovskaya, Natalya A. Shalnikova, and

Sempervirens Fund for kindly providing the photos.

Funding

This work was carried out within the framework of

the State Assignment for the Lomonosov Moscow State

University and State Assignment for the Emanuel In-

stitute of Biochemical Physics, Russian Academy of

Sciences (no.001201253314).

Ethics approval and consent to participate

This work does not contain any studies involving hu-

man and animal subjects.

Conflict of interest

The authors of this work declare that they have no

conflicts of interest.

S. D.  Gvozdover’s first paper on NMR [Gvozdover and Magazanik, 1950] was published right in 1950.

KESSENIKH, PTUSHENKOS428

BIOCHEMISTRY (Moscow) Vol. 90 Suppl. 2 2025

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