FRANCK (Franck), James( German-American physicist, Nobel Prize in physics. 1925)
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Biography FRANCK (Franck), James
German-American physicist James Franck was born in Hamburg, the son of Jacob Frank, a banker, and Rebecca Frank, nee Drucker, who was from a famous family of rabbis. In the Hamburg High School, where he attended the FA, the emphasis was on classical education and languages - things that did not interest him. When in 1901. his father sent him to the University of Heidelberg, it is expected that F. will study law and economics, then will the traditional for the family banking. However, in Heidelberg, he also studied geology and chemistry, here he met Max Born, who has supported interest F. to science and became his lifelong friend. Later Born persuaded parents F. help his son in his quest to get scientific education.
In 1902, Mr.. F. moved to Berlin University, the then center of physical science and education in Germany. Doctoral degree he received in 1906. for the study of motion of ions in gas discharges. After a brief period working as an assistant-lecturer at the University of Frankfurt F. returned to Berlin University assistant physics laboratory and became a lecturer at the same university in 1911
F. began to work together with Gustav Hertz in 1913. In their first joint experiment F. and Herz investigated the interaction of electrons with atoms of noble gases of low density. They found that at low energies, electrons collide with atoms of noble gases without large loss of energy, ie. these collisions are elastic. In 1914, Mr.. researchers repeated their experiments using mercury vapor, and found that the electrons interact strongly with atoms of mercury, giving them a larger share of its energy. It is this work on inelastic collisions resulted in F. and Hertz to the discovery of the quantized energy transfer in collisions of atoms and electrons. Between 1900. and the time of experiments F. and Hertz, Max Planck, Albert Einstein and Niels Bohr created the quantum theory. This theory assumes that energy is not transmitted continuously, and discrete portions, which Einstein called quanta. The energy of photon expressed in terms of the frequency emitted or absorbed energy through the multiplier, known as Planck's constant. In 1913, Mr.. Bohr proposed a quantum model of the atom, . in which the electrons move around the nucleus only in certain orbits, . the special energy states, where the electrons are transferred from one orbit to another, . they emit or absorb quanta,
. Bohr's model was responsible for some of the then opposition to the nuclear model of the atom and, in particular, explain the spectra of elements. When heated, the gas absorbs energy in the form of heat, then releases it in the form of light, each element emits light of specific colors, or wavelengths, which can be divided to arrive at a series of lines, called the spectrum of. According to Bohr, every line of the spectrum corresponds to a specific amount of energy emitted during the transition of an electron with a higher energy orbit to a lower. Although this theory has aroused great interest among physicists and largely persuaded them to justice, quantum theory, it still has not been confirmed experimentally.
In his famous experiments, F. and Hertz showed that the electrons can transfer energy to the atom of mercury only integer multiples of 4, 9 electron volts. (One electron-volts - this is the amount of energy, . acquired by an electron, . accelerated by using the voltage in one volt.) Then, they suggested, . that the mercury atoms can radiate energy, . equal one, . they absorb, . giving a spectral line with the calculated wavelength,
. Having discovered this line in the spectrum of mercury, F. and Hertz concluded that the atoms by bombarding them with electrons and absorb and emit energy indivisible units, or quanta. Working with other elements of the gases confirmed this discovery.
Experiments F. and Hertz not only demonstrated the existence of energy quanta more convincingly than any previous work, but also gave a new method for measuring Planck's constant. Moreover, their results were the experimental confirmation of the Bohr model of the atom. Neither the FA nor Hertz did not understand this at first, paying little attention to the assumption of Bohr. However, Bohr and others soon benefited from the F. and Hertz, to confirm the ideas of Bohr, had a profound influence on the development of quantum theory.
In 1926, Mr.. The Royal Swedish Academy of Sciences awarded the Nobel Prize in Physics for 1925. F. and Hertz 'discovery of the laws of collisions between electrons and atoms'. In his Nobel lecture F. pointed out that 'the first work of Niels Bohr on atomic theory appeared six months before the end of this work'. 'Later on, - he continued - it seemed to me quite inexplicable why we are not aware of the fundamental significance of Bohr's theory, to such an extent that never even mentioned it in his scientific paper'.
Research F. were interrupted by the outbreak in 1914. First World War. He served as an officer in the Russian-germanskom front, then because of the serious illness of dysentery has been sent to the rear for long-term care. In 1917. F. became head of the section at the Institute of Physical Chemistry, Kaiser Wilhelm, working under the guidance of Fritz Haber. There he continued his research on inelastic collisions of electrons with atoms and molecules. F. and his colleagues found that the electrons can excite the atom (forcing him to absorb the energy) so that he can not get rid of the excitation energy by emitting light. These atoms are in a 'metastable state', in the terminology introduced by F. and his staff, and can lose only the excitation energy in collisions with particles. Metastable states play an important role in chemistry and physics: in photosynthesis, for example, they are crucial for the accumulation of energy in plants. Later F. turned to photosynthesis, which remained the most important to him the subject of research the last 30 years of his life.
When Max Born in 1912. asked to lead the department of theoretical physics at Gottingen University, he agreed on condition that F. headed the Department of Experimental Physics. The next 12 years, two scientists worked closely together, discussing with each other every aspect of their work. When Bourne began to develop a formal mathematical apparatus of quantum theory, which he called quantum mechanics, profound scientific intuition F. proved invaluable to him. In GцІttingen F. first studied the interaction of atoms with electrons, light and other atoms. His work on the formation and structure of the molecules, which used molecular spectra, allowed him to identify the main chemical properties of the spectroscopic measurements. Approach he developed with his colleague Edward Condon, known as the Franck - Condon.
Soon after Adolf Hitler became Chancellor (1933), Germanic government began to remove Jews from academic positions. Although F. a Jew, but his achievements during the First World War, first to protect him from removal from office. He nevertheless he resigned, not wanting to carry out instructions to dismiss staff and students of Jewish. He stated his disagreement publicly, that was an act of personal courage. Before leaving Germany, F., despite the economic depression, was able to find work abroad for every member of his laboratory.
After one year at the Research Institute of Bohr in Copenhagen, F. in 1935. emigrated to the United States, becoming a professor at Johns Hopkins University. Here he began to study the influence of light on chemicals and began work on unraveling the mysteries of photosynthesis, the fundamental photochemical processes in nature. In 1938. He was appointed professor of physical chemistry and director of the new laboratory of photosynthesis, University of Chicago. Three years later he became an American citizen.
After the U.S. entry into World War II F. directed chemical department of the University of Chicago Metallurgical Laboratory, which was a part of the Manhattan Project to build atomic bomb. While the prospect of a nuclear weapons was hateful to him, he feared that Germany is moving towards the same goal. After the defeat of Germany F. headed the committee, who has studied social and political consequences of use of nuclear weapons. The committee's report, made in June 1945. and known as 'Frank's report', insisted that nuclear weapons are not used for military purposes up until it can be demonstrated in some desert place, representatives of all nations, particularly the Japanese. The report also predicted the risk of a nuclear arms race. These recommendations have neglected, and the Japanese cities of Hiroshima and Nagasaki were destroyed in August of that year.
In 1907, Mr.. F. married Ingrid Josephson, they had two daughters. Ingrid Frank died in 1942. after long illness. In 1946, Mr.. F. married Hertha Sponer, his former student, who became professor of physics at Duke University in Durham (North Carolina). After the Second World War, F. returned to his studies at the University of Chicago, dividing time between Chicago and the family home in Durham. In 1949, Mr.. He became an honorary professor emeritus, University of Chicago and continued his active research, especially on photosynthesis.
F. died suddenly, when he and his wife in 1964. visiting friends in GцІttingen.
His colleagues knew F. as a kind, gentle, democratic rights, and many of them have repeatedly appealed to him for advice on scientific and personal matters. They remember his public protest against the Nazis and his attempt to prevent the use of atomic bombs against the civilian population as examples of moral courage.
In addition to the Nobel Prize, F. received the Medal of the Max Planck Germanskogo Physical Society (1951) and the Rumford Medal of the American Academy of Arts and Sciences (1955). In 1953, Mr.. he became an honorary citizen of Goettingen. F. was a member of many scientific organizations, . including the U.S. National Academy of Sciences, . Association for the Advancement of Science, . American Philosophical Society, . American Chemical Society, . American Botanical Society and the Royal Society.,