Hans Frauenfelder (July 28, 1922 – July 10, 2022) was an American physicist and biophysicist notable for his discovery of

perturbed angular correlation The perturbed γ-γ angular correlation, PAC for short or PAC-Spectroscopy, is a method of nuclear solid-state physics with which magnetic and electric fields in crystal structures can be measured. In doing so, electrical field gradients and the L ...

(PAC) in 1951. In the modern day, PAC

spectroscopy Spectroscopy is the field of study that measures and interprets the electromagnetic spectra that result from the interaction between electromagnetic radiation and matter as a function of the wavelength or frequency of the radiation. Matter wa ...

is widely used in the study of

condensed matter physics Condensed matter physics is the field of physics that deals with the macroscopic and microscopic physical properties of matter, especially the solid and liquid phases which arise from electromagnetic forces between atoms. More generally, the sub ...

. Within

biophysics Biophysics is an interdisciplinary science that applies approaches and methods traditionally used in physics to study biological phenomena. Biophysics covers all scales of biological organization, from molecular to organismic and populations. ...

, he is known for his experimental and theoretical research on the dynamical behavior of

protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, respo ...

tertiary structure Protein tertiary structure is the three dimensional shape of a protein. The tertiary structure will have a single polypeptide chain "backbone" with one or more protein secondary structures, the protein domains. Amino acid side chains may int ...

Education

Frauenfelder received his Dr. sc. nat. in physics in 1950 at the Swiss Federal Institute of Technology (ETH) in Zurich under

Paul Scherrer Paul Hermann Scherrer (3 February 1890 – 25 September 1969) was a Swiss physicist. Born in St. Gallen, Switzerland, he studied at Göttingen, Germany, before becoming a lecturer there. Later, Scherrer became head of the Department of Physics ...

, his thesis being on the study of radioactive surfaces. At ETH, he was also taught by

Gregor Wentzel Gregor Wentzel (17 February 1898 – 12 August 1978) was a German physicist known for development of quantum mechanics. Wentzel, Hendrik Kramers, and Léon Brillouin developed the Wentzel–Kramers–Brillouin approximation in 1926. In his early y ...

and

Wolfgang Pauli Wolfgang Ernst Pauli (; ; 25 April 1900 – 15 December 1958) was an Austrian theoretical physicist and one of the pioneers of quantum physics. In 1945, after having been nominated by Albert Einstein, Pauli received the Nobel Prize in Physics fo ...

. Through Pauli, he also got to know many of the leading scientists such as

Hendrik Kramers Hendrik Anthony "Hans" Kramers (17 December 1894 – 24 April 1952) was a Dutch physicist who worked with Niels Bohr to understand how electromagnetic waves interact with matter and made important contributions to quantum mechanics and statistical ...

Werner Heisenberg Werner Karl Heisenberg () (5 December 1901 – 1 February 1976) was a German theoretical physicist and one of the main pioneers of the theory of quantum mechanics. He published his work in 1925 in a breakthrough paper. In the subsequent series ...

, Hans Jensen, and

Wolfgang Paul Wolfgang Paul (; 10 August 1913 – 7 December 1993) was a German physicist, who co-developed the non-magnetic quadrupole mass filter which laid the foundation for what is now called an ion trap. He shared one-half of the Nobel Prize in Ph ...

Career

Frauenfelder migrated to the United States in 1952, joining the Department of Physics at the

University of Illinois at Urbana-Champaign The University of Illinois Urbana-Champaign (U of I, Illinois, University of Illinois, or UIUC) is a public land-grant research university in Illinois in the twin cities of Champaign and Urbana. It is the flagship institution of the Univ ...

as a research associate. He stayed at the UIUC till 1992, ultimately as Center for Advanced Study Professor of Physics, Chemistry, and Biophysics. His research interests included

nuclear physics Nuclear physics is the field of physics that studies atomic nuclei and their constituents and interactions, in addition to the study of other forms of nuclear matter. Nuclear physics should not be confused with atomic physics, which studies the ...

particle physics Particle physics or high energy physics is the study of fundamental particles and forces that constitute matter and radiation. The fundamental particles in the universe are classified in the Standard Model as fermions (matter particles) an ...

conservation laws In physics, a conservation law states that a particular measurable property of an isolated physical system does not change as the system evolves over time. Exact conservation laws include conservation of energy, conservation of linear momentum, ...

, the

Mössbauer effect The Mössbauer effect, or recoilless nuclear resonance fluorescence, is a physical phenomenon discovered by Rudolf Mössbauer in 1958. It involves the resonant and recoil-free emission and absorption of gamma radiation by atomic nuclei bound in ...

, and the

protein folding Protein folding is the physical process by which a protein chain is translated to its native three-dimensional structure, typically a "folded" conformation by which the protein becomes biologically functional. Via an expeditious and reproduci ...

and motions. Frauenfelder was a visiting Scientist at the European Organization for Nuclear Research (CERN) in 1958/59, 1963 and 1973. In 1992, Frauenfelder moved to the

Los Alamos National Laboratory Los Alamos National Laboratory (often shortened as Los Alamos and LANL) is one of the sixteen research and development laboratories of the United States Department of Energy (DOE), located a short distance northwest of Santa Fe, New Mexico, ...

where he directed the Center for Nonlinear Studies
CNLS
until 1997. In 1997, he left CNLS and joined the theoretical biology and biophysics group at Los Alamos (T-10 recently renamed T-6) and continued research in biophysics. Frauenfelder was the inventor of the "Frauenfelder Rules", which provide a guideline about the most successful way to run a seminar at a research workshop, according to which a presentation should take up no more than 66% of the allotted time, the rest being used for questions and in-depth discussion.

Personal life

Frauenfelder died in

Tesuque, New Mexico Tesuque (Tewa: Tetsʼúgéh Ówîngeh / Tetsugé Oweengé ) is a census-designated place (CDP) in Santa Fe County, New Mexico, United States. It is part of the Santa Fe, New Mexico, Metropolitan Statistical Area. The population was 909 at the 2 ...

, on July 10, 2022, eighteen days away from his 100th birthday.

Honors

Frauenfelder was elected a Fellow of the American Physical society in 1961. He was a member of the

National Academy of Sciences The National Academy of Sciences (NAS) is a United States nonprofit, non-governmental organization. NAS is part of the National Academies of Sciences, Engineering, and Medicine, along with the National Academy of Engineering (NAE) and the Nati ...

(elected in 1975), the

American Philosophical Society The American Philosophical Society (APS), founded in 1743 in Philadelphia, is a scholarly organization that promotes knowledge in the sciences and humanities through research, professional meetings, publications, library resources, and communit ...

, and a Foreign Member of the

Royal Swedish Academy of Sciences The Royal Swedish Academy of Sciences ( sv, Kungliga Vetenskapsakademien) is one of the Swedish Royal Academies, royal academies of Sweden. Founded on 2 June 1739, it is an independent, non-governmental scientific organization that takes special ...

Publications

* Thomas G. Ebrey, Hans Frauenfelder, Barry Honig, and Koji Nakanishi ''Biophysical Studies,'' University of Illinois Press (1988) * Hans Frauenfelder, ''The Mössbauer Effect,'' W. A. Benjamin, Inc. (1962) ASIN B000Q7QEBG * Hans Frauenfelder and Ernest M. Henley, ''Subatomic Physics,'' Benjamin Cummings (1991)

References

External links

References on Perturbed Angular Correlation (PAC)

Frauenfelder's homepage

Frauenfelder's math genealogy
{{DEFAULTSORT:Frauenfelder, Hans 1922 births 2022 deaths American biophysicists American nuclear physicists 21st-century American physicists ETH Zurich alumni Members of the United States National Academy of Sciences Probability theorists Swiss biophysicists Swiss nuclear physicists Swiss physicists University of Illinois Urbana-Champaign faculty Fellows of the American Physical Society Members of the American Philosophical Society Fellows of the American Academy of Arts and Sciences Fellows of the American Association for the Advancement of Science Members of the Royal Swedish Academy of Sciences Los Alamos National Laboratory personnel People associated with CERN Swiss emigrants to the United States