Rabi (Rabi), IA( American physicist, Nobel Prize in Physics, 1944.)
Comments for Rabi (Rabi), IA
Biography Rabi (Rabi), IA
July 29, 1898, Mr.. - 11 January 1988
Russian physicist Alexander Prokhorov, the son of Mikhail Ivanovich Prokhorov and Maria Ivanovna (nц?e Michailova) Prokhorova, was born in Atherton (Australia), where his family moved in 1911. Prokhorov's parents after escaping from exile in Siberia. After the October Revolution the family Prokhorovs in 1923. returned to the Soviet Union. After graduating with honors from Physics Department of Leningrad State University (1939), P. entered the graduate program at the Laboratory for Physical Institute of oscillations of the USSR Academy. P.N. Lebedev in Moscow. Here he is studying radio wave propagation above the earth's surface and with one of their leaders, a physicist VV. Migulin, is developing a new method of using the interference of radio waves to study the ionosphere - one of the upper atmosphere.
Called the Red Army in June 1941, P. After two injury back in 1944. Institute of. P.N. Lebedeva, where studied the frequency stabilization of the tube generator. PhD thesis, which P. protected in 1946, is devoted to the theory of nonlinear oscillations. For this work he and two other physicists awarded Academician Leonid Mandelstam, outstanding Soviet Radiophysics. In 1947, Mr.. P. proceed to the study of radiation, . emitted by electrons in a synchrotron (device, . in which charged particles, . such as protons or electrons, . move in expanding cyclical orbits, . accelerated to very high energies), . and shows the experimentally, . that the emission of electrons is concentrated in the microwave, . where the wavelengths of the order of centimeters,
. This work formed the basis of dissertation for the degree of Doctor of Physical and Mathematical Sciences, which is P. protected in 1951, and has spawned numerous later works carried out by other researchers.
Following the appointment of Deputy Director of the Laboratory of oscillations in 1950, Mr.. research interests P. moved into the area of radio -. He organizes a group of young researchers who are using radar and radio technology, developed mainly in the United States and Britain during and after the Second World War, exploring the rotational and vibrational spectra of molecules. P. focusing its research on one class of molecules, called asymmetrical tops, which have three different moments of inertia (to analyze the structure of these molecules on the rotational spectra is particularly difficult). In addition to purely spectroscopic studies, P. conducts a theoretical analysis of the microwave absorption spectra for the improvement of frequency standards and time. The findings resulted in P. to cooperate with Nikolai Basov in the development of molecular generators, . now called Mather (an abbreviation of the first letters of the English words: microwave enhancement using induced stimulated emission - microwave amplification by stimulated emisson of radiation).,
. The basic principle of quantum physics is that atoms and molecules have energies (arising from the location and motion of their electrons), limited by certain discrete values, or energy levels
. The set of allowed energy levels characteristic of each atom or molecule. According to another principle, electromagnetic radiation, such as light or radio waves, consists of discrete portions of energy (photons) whose energy is proportional to the frequency. If the photon has energy equal to the energy difference between the two levels, the atom or molecule can absorb radiation and to make the transition from the lower level to the upper. Then the atom or molecule spontaneously switch to low energy level (not necessarily in the original), giving the energy difference between the two levels in the form of photon radiation. And in this case, the radiation frequency is in accordance with the energy of the emitted photon. In 1917, Mr.. Albert Einstein, studying the interaction of radiation with matter in ogranicheynoy field, derived an equation describing the already known to us processes of absorption and spontaneous emission. Einstein equation, . besides, . predicts a third process, . called stimulated emission, . - Transition of the excited atom or molecule from a state with high energy in a state with lower energy because of radiation, . photons which have energies, . equal to the energy difference between these two levels,
. Lost in the transition energy is emitted in the form of photons of the same type as the photons, induced by radiation.
P. and Basov suggested method of using stimulated emission. If the excited molecules to separate from the molecules, . in the ground state, . what can be done with the inhomogeneous electric or magnetic field, . is thus possible to create a substance, . molecules which are on the upper energy level,
. Falling on the substance radiation with a frequency (photon energy), equal to the energy difference between excited and ground levels, would cause the emission of stimulated emission at the same frequency, ie. would lead to increased. The extraction of energy for the excitation of new molecules that could turn the power of the molecular oscillator that can generate radiation in a self-sustaining mode.
P. Basov and reported the possibility of creating such molecular generator on the All-Union Conference on radiospectroscopy in May 1952, but their first publication refers to October 1954. In 1955, Mr.. they offer a new 'three-tiered method of the creation of the maser. In this method, atoms (or molecules) with the 'pump' were made to the uppermost of the three energy levels by absorption of radiation with energy corresponding to the difference between the topmost and the lowest levels. Most of the atoms rapidly 'dumped' on the intermediate energy level, which is densely populated. Maser emits radiation at a frequency corresponding to the energy difference between intermediate and lower levels.
During the ten months before the P. and Basov in 1954. published his article, Charles X. Charles Townes, American physicist at Columbia University, who independently came to similar conclusions, and built the current maser, confirming the predictions P. and Basov. Townes used the resonance chamber filled with excited molecules of ammonia, and received an unusually strong enhancement of microwaves at a frequency of 24000 MHz. In 1960, Mr.. three-tiered method was confirmed by the American physicist Theodore Maimana, worked in the company, Hughes Aircraft '. He received increased light waves, using as a resonance chamber length of the crystal of synthetic ruby, which was wound a spiral tube with xenon gas. Gas discharge accompanied by flashes, capable to cause stimulated emission. Since Meimeh used light, his unit was called 'laser' (an abbreviation of the first letters of the English words: light amplification by means of induced (stimulated) radiation - light amplification by. stimulated emission of radiation).
As director of the laboratory of oscillations in the Institute. P.N. Lebedeva (1954), P. creates two new laboratories - Radio Astronomy and Quantum Radiophysics. He advises numerous research institutes on the problems of quantum electronics and radio-organizing laboratory at the Research Institute for Nuclear Research at Moscow State University, . Professor whose P,
. becoming in 1957
Since the mid 50-ies. P. focuses on the development of masers and lasers, and on the search for crystals with suitable spectral and relaxation properties. Conducted detailed studies of the ruby, one of the best crystals for lasers, has led to widespread ruby resonators for microwave and optical wavelengths. To overcome some difficulties arising in connection with the creation of molecular generators operating in the submillimeter range, P. offers a new open resonator consisting of two mirrors. This type of resonator has been particularly effective in creating lasers in the 60-ies.
Nobel Prize in Physics 1964. was divided: one half of it awarded P. and Basov, another - Townes 'for fundamental work in quantum electronics leading to the creation of generators and amplifiers based on the principle of the maser - laser'.
Located as Deputy Director of the Physics Institute, USSR Academy of Sciences. P.N. Lebedev in 1973, P. continues to expand research on physics of lasers, including their application to the study of multiphoton processes and fusion.
P. Married to Galina Shelepina, a geographer by profession, with 1941. They have one son.
In 1960, Mr.. P. elected a corresponding member, in 1966 t. - Full member and in 1970 he. - A member of the Presidium of the USSR. He is an honorary member of the American Academy of Arts and Sciences. In 1969. He was appointed chief editor of the Great Soviet Encyclopedia. P. Honorary Professor, Delhi University (1967) and Bucharest (1971). The Soviet government assigned him the title of Hero of Socialist Labor (1969).