Franco Rasetti
   HOME

TheInfoList



OR:

Franco Dino Rasetti (August 10, 1901 – December 5, 2001) was an Italian (later naturalized American) physicist, paleontologist and botanist. Together with
Enrico Fermi Enrico Fermi (; 29 September 1901 – 28 November 1954) was an Italian (later naturalized American) physicist and the creator of the world's first nuclear reactor, the Chicago Pile-1. He has been called the "architect of the nuclear age" and ...
, he discovered key processes leading to
nuclear fission Nuclear fission is a reaction in which the nucleus of an atom splits into two or more smaller nuclei. The fission process often produces gamma photons, and releases a very large amount of energy even by the energetic standards of radio ...
. Rasetti refused to work on the
Manhattan Project The Manhattan Project was a research and development undertaking during World War II that produced the first nuclear weapons. It was led by the United States with the support of the United Kingdom and Canada. From 1942 to 1946, the project w ...
on moral grounds.


Life and career

Rasetti was born in
Castiglione del Lago Castiglione del Lago is a town in the province of Perugia of Umbria (central Italy), on the southwest corner of Lake Trasimeno. Orvieto is south, Chiusi is to the south west, Arezzo is to the north west, Cortona is to the north and Perugi ...
, Italy. He earned a ''
Laurea In Italy, the ''laurea'' is the main post-secondary academic degree. The name originally referred literally to the laurel wreath, since ancient times a sign of honor and now worn by Italian students right after their official graduation ceremony ...
'' in physics at the
University of Pisa The University of Pisa ( it, Università di Pisa, UniPi), officially founded in 1343, is one of the oldest universities in Europe. History The Origins The University of Pisa was officially founded in 1343, although various scholars place ...
in 1923, and Fermi invited him to join his research group at the University of Rome. In 1928-1929 during a stay at the
California Institute of Technology The California Institute of Technology (branded as Caltech or CIT)The university itself only spells its short form as "Caltech"; the institution considers other spellings such a"Cal Tech" and "CalTech" incorrect. The institute is also occasional ...
(Caltech), he carried out experiments on the
Raman effect Raman scattering or the Raman effect () is the inelastic scattering of photons by matter, meaning that there is both an exchange of energy and a change in the light's direction. Typically this effect involves vibrational energy being gained by a ...
. He measured a spectrum of dinitrogen in 1929 which provided the first experimental evidence that the
atomic nucleus The atomic nucleus is the small, dense region consisting of protons and neutrons at the center of an atom, discovered in 1911 by Ernest Rutherford based on the 1909 Geiger–Marsden gold foil experiment. After the discovery of the neutron i ...
is not composed of protons and electrons, as was incorrectly believed at the time.Caltech oral history interview
by
Judith R. Goodstein Judith Ronnie Goodstein (née Koral, born 1939) is an American historian of science, historian of mathematics, archivist, and book author. She worked for many years at the California Institute of Technology (Caltech), where she is University Archi ...
, 4 February 1982
In 1930, he was appointed to the chair in
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 ...
at the Physics Institute of the University of Rome, at that time still located in Via Panisperna. His colleagues included
Oscar D'Agostino Oscar D'Agostino (29 August 1901 – 16 March 1975) was an Italian chemist and one of the so-called ''Via Panisperna boys'', the group of young scientists led by Enrico Fermi: all of them were physicists, except for D'Agostino, who was a chemist. ...
,
Emilio Segrè Emilio Gino Segrè (1 February 1905 – 22 April 1989) was an Italian-American physicist and Nobel laureate, who discovered the elements technetium and astatine, and the antiproton, a subatomic antiparticle, for which he was awarded the Nobel ...
,
Edoardo Amaldi Edoardo Amaldi (5 September 1908 – 5 December 1989) was an Italian physicist. He coined the term "neutrino" in conversations with Enrico Fermi distinguishing it from the heavier "neutron". He has been described as "one of the leading nuclear ...
,
Ettore Majorana Ettore Majorana (,, uploaded 19 April 2013, retrieved 14 December 2019 ; born on 5 August 1906 – possibly dying after 1959) was an Italian theoretical physicist who worked on neutrino masses. On 25 March 1938, he disappeared under mysteri ...
and Enrico Fermi, as well as the institute's director
Orso Mario Corbino Orso Mario Corbino (30 April 1876, Augusta – 23 January 1937, Rome) was an Italian physicist and politician. His younger brother was Epicarmo Corbino. He served as the minister for education in 1921 and as the minister for economy in 1921. H ...
. Rasetti remained in this position until 1938. Rasetti was one of Fermi's main collaborators in the study of
neutron The neutron is a subatomic particle, symbol or , which has a neutral (not positive or negative) charge, and a mass slightly greater than that of a proton. Protons and neutrons constitute the nuclei of atoms. Since protons and neutrons beh ...
s and neutron-induced radioactivity. In 1934, he participated in the discovery of the artificial radioactivity of fluorine and aluminium which would be critical in the development of the
atomic bomb A nuclear weapon is an explosive device that derives its destructive force from nuclear reactions, either fission (fission bomb) or a combination of fission and fusion reactions (thermonuclear bomb), producing a nuclear explosion. Both bomb ...
. In 1939 the advance of fascism and the deteriorating Italian political situation led him to leave Italy, following the example of his colleagues Fermi, Segré and
Bruno Pontecorvo Bruno Pontecorvo (; russian: Бру́но Макси́мович Понтеко́рво, ''Bruno Maksimovich Pontecorvo''; 22 August 1913 – 24 September 1993) was an Italian and Soviet nuclear physicist, an early assistant of Enrico Fermi an ...
. With Fermi he had discovered the key to
nuclear fission Nuclear fission is a reaction in which the nucleus of an atom splits into two or more smaller nuclei. The fission process often produces gamma photons, and releases a very large amount of energy even by the energetic standards of radio ...
, but unlike many of his colleagues, he refused for moral reasons to work on the
Manhattan project The Manhattan Project was a research and development undertaking during World War II that produced the first nuclear weapons. It was led by the United States with the support of the United Kingdom and Canada. From 1942 to 1946, the project w ...
. From 1939 to 1947, he taught at
Laval University Laval means ''The Valley'' in old French and is the name of: People * House of Laval, a French noble family originating from the town of Laval, Mayenne * Laval (surname) Places Belgium * Laval, a village in the municipality of Sainte-Ode, Luxemb ...
in
Quebec City Quebec City ( or ; french: Ville de Québec), officially Québec (), is the capital city of the Provinces and territories of Canada, Canadian province of Quebec. As of July 2021, the city had a population of 549,459, and the Communauté métrop ...
(Canada), where he was founding chairman of the physics department. In 1947, he moved to the United States where he became a
naturalized citizen Naturalization (or naturalisation) is the legal act or process by which a non-citizen of a country may acquire citizenship or nationality of that country. It may be done automatically by a statute, i.e., without any effort on the part of the in ...
in 1952. Until 1967, he held a chair in physics at
Johns Hopkins University Johns Hopkins University (Johns Hopkins, Hopkins, or JHU) is a private university, private research university in Baltimore, Maryland. Founded in 1876, Johns Hopkins is the oldest research university in the United States and in the western hem ...
in
Baltimore Baltimore ( , locally: or ) is the List of municipalities in Maryland, most populous city in the U.S. state of Maryland, fourth most populous city in the Mid-Atlantic (United States), Mid-Atlantic, and List of United States cities by popula ...
. From the 1950s onward, he gradually shifted his commitment to naturalistic studies, which had been his great interest outside of physics already as a child. He devoted himself to geology, paleontology, entomology, and botany, becoming one of the most authoritative scholars of the Cambrian geological era. He died in
Waremme Waremme (; nl, Borgworm, ; wa, Wareme) is a city and municipality of Wallonia located in the province of Liège, in Belgium. The city is located on the River Geer ( nl, Jeker), in the loessic Haspengouw region. The economy is based on the c ...
, Belgium at the age of 100. The ''Nature'' obituary noted that Rasetti was one of the ''most prolific generalists'' whose ''work and writing are noted for the elegance, simplicity and beauty''.


Raman spectroscopy and the model of the atomic nucleus

After the discovery of
Raman scattering Raman scattering or the Raman effect () is the inelastic scattering of photons by matter, meaning that there is both an exchange of energy and a change in the light's direction. Typically this effect involves vibrational energy being gained by a ...
by organic liquids, Rasetti decided to study the same phenomenon in gases at high pressure during his stay at Caltech in 1928–29. The spectra showed vibrational transitions with rotational fine structure. In the homonuclear diatomic molecules H2, N2 and O2, Rasetti found an alternation of strong and weak lines. This alternation was explained by
Gerhard Herzberg Gerhard Heinrich Friedrich Otto Julius Herzberg, (; December 25, 1904 – March 3, 1999) was a German-Canadian pioneering physicist and physical chemist, who won the Nobel Prize for Chemistry in 1971, "for his contributions to the knowledge o ...
and
Walter Heitler Walter Heinrich Heitler (; 2 January 1904 – 15 November 1981) was a German physicist who made contributions to quantum electrodynamics and quantum field theory. He brought chemistry under quantum mechanics through his theory of valence bond ...
as a consequence of nuclear spin isomerism. For dihydrogen, each nucleus is a proton of spin 1/2, so that it can be shown using
quantum mechanics Quantum mechanics is a fundamental theory in physics that provides a description of the physical properties of nature at the scale of atoms and subatomic particles. It is the foundation of all quantum physics including quantum chemistry, ...
and the
Pauli exclusion principle In quantum mechanics, the Pauli exclusion principle states that two or more identical particles with half-integer spins (i.e. fermions) cannot occupy the same quantum state within a quantum system simultaneously. This principle was formulated ...
that the odd rotational levels are more populated than the even levels.P.W. Atkins and J. de Paula, "Atkins' Physical Chemistry" (8th edn, W.H. Freeman 2006) p.451 The transitions originating from odd levels are therefore more intense as observed by Rasetti. In dinitrogen, however, Rasetti observed that the lines originating from even levels are more intense. This implies by a similar analysis that the
nuclear spin In atomic physics, the spin quantum number is a quantum number (designated ) which describes the intrinsic angular momentum (or spin angular momentum, or simply spin) of an electron or other particle. The phrase was originally used to describe th ...
of nitrogen is an integer. This result was difficult to understand at the time, however, because the
neutron The neutron is a subatomic particle, symbol or , which has a neutral (not positive or negative) charge, and a mass slightly greater than that of a proton. Protons and neutrons constitute the nuclei of atoms. Since protons and neutrons beh ...
had not yet been discovered, and it was thought that the 14N nucleus contains 14 protons and 7 electrons, or an odd number (21) of particles in total which would correspond to a half-integral spin. The Raman spectrum observed by Rasetti provided the first experimental evidence that this proton-electron model of the nucleus is inadequate, because the predicted half-integral spin has as a consequence that transitions from odd rotational levels would be more intense than those from even levels, due to nuclear spin isomerism as shown by Herzberg and Heitler for dihydrogen. After the discovery of the neutron in 1932,
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 ...
proposed that the nucleus contains protons and neutrons, and the 14N nucleus contains 7 protons and 7 neutrons. The even total number (14) of particles corresponds to an integral spin in agreement with Rasetti's spectrum. He is also credited with the first example of electronic (as opposed to vibronic) Raman scattering in
nitric oxide Nitric oxide (nitrogen oxide or nitrogen monoxide) is a colorless gas with the formula . It is one of the principal oxides of nitrogen. Nitric oxide is a free radical: it has an unpaired electron, which is sometimes denoted by a dot in its che ...
.


Awards

*In 1952 he was awarded the
Charles Doolittle Walcott Medal Charles Doolittle Walcott Medal is an award presented by the National Academy of Sciences every five years to promote research and study in the fields of Precambrian and Cambrian life and history. The medal was established and endowed in 1934 by ...
by 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 ...
for his contributions to Cambrian paleontology.


References


External links


Franco Dino Rasetti Papers
from the
Smithsonian Institution Archives Smithsonian Libraries and Archives is an institutional archives and library system comprising 21 branch libraries serving the various Smithsonian Institution museums and research centers. The Libraries and Archives serve Smithsonian Institution ...
{{DEFAULTSORT:Rasetti, Franco 1901 births 2001 deaths People from Castiglione del Lago Italian emigrants to the United States 20th-century Italian physicists Italian nuclear physicists 20th-century American physicists American nuclear physicists Université Laval faculty Italian centenarians American centenarians Men centenarians Sapienza University of Rome faculty Charles Doolittle Walcott Medal winners Italian paleontologists Italian exiles Spectroscopists