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Solomon Isaakovich Pekar
Solomon Isaakovich Pekar ( uk, Соломон Ісаакович Пекар; russian: Соломон Исаакович Пекар; 16 March 1917 – 8 July 1985) was a Soviet theoretical physicist, born in Kyiv, Ukraine. He was a full Member of the Ukrainian Academy of Sciences and is known for his fundamental contributions to condensed matter physics, especially for introducing and advancing the concept of polaron as a charge carrier in solids. Career In 1941 Pekar submitted his Candidate of Science thesis on nonlinear theory of semiconductor rectifiers for which he was awarded Doctor of Science Degree, this work was strongly approved by Lev Landau. In 1946, Pekar developed a concept of a polaron and coined this term. The model developed in this paper is macroscopic and based on electrostatic coupling of an electron to polar optical phonons. This coupling results in dressing of the electron by a cloud of virtual phonons and renormalization of its energy spectrum. In the s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kyiv
Kyiv, also spelled Kiev, is the capital and most populous city of Ukraine. It is in north-central Ukraine along the Dnieper, Dnieper River. As of 1 January 2021, its population was 2,962,180, making Kyiv the List of European cities by population within city limits, seventh-most populous city in Europe. Kyiv is an important industrial, scientific, educational, and cultural center in Eastern Europe. It is home to many High tech, high-tech industries, higher education institutions, and historical landmarks. The city has an extensive system of Transport in Kyiv, public transport and infrastructure, including the Kyiv Metro. The city's name is said to derive from the name of Kyi, one of its four legendary founders. During History of Kyiv, its history, Kyiv, one of the oldest cities in Eastern Europe, passed through several stages of prominence and obscurity. The city probably existed as a commercial center as early as the 5th century. A Slavs, Slavic settlement on the great trade ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polariton
In physics, polaritons are quasiparticles resulting from strong coupling of electromagnetic waves with an electric or magnetic dipole-carrying excitation. They are an expression of the common quantum phenomenon known as level repulsion, also known as the avoided crossing principle. Polaritons describe the crossing of the dispersion of light with any interacting resonance. To this extent polaritons can also be thought of as the new normal modes of a given material or structure arising from the strong coupling of the bare modes, which are the photon and the dipolar oscillation. The polariton is a bosonic quasiparticle, and should not be confused with the polaron (a fermionic quasiparticle), which is an electron plus an attached phonon cloud. Whenever the polariton picture is valid (i.e., when the weak coupling limit is an invalid approximation), the model of photons propagating freely in crystals is insufficient. A major feature of polaritons is a strong dependency of the propag ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Theoretical Physicists
The following is a partial list of notable theoretical physicists. Arranged by century of birth, then century of death, then year of birth, then year of death, then alphabetically by surname. For explanation of symbols, see Notes at end of this article. Ancient times * Thales (c. 624 – c. 546 BCE) * Pythagoras^* (c. 570 – c. 495 BCE) * Democritus° (c. 460 – c. 370 BCE) * Aristotle‡ (384–322 BCE) * Archimedesº* (c. 287 – c. 212 BCE) * Hypatia^ªº (c. 350–370; died 415 AD) Middle Ages * Al Farabi (c. 872 – c. 950) * Ibn al-Haytham (c. 965 – c. 1040) * Al Beruni (c. 973 – c. 1048) * Omar Khayyám (c. 1048 – c. 1131) * Nasir al-Din Tusi (1201–1274) * Jean Buridan (1301 – c. 1359/62) * Nicole Oresme (c. 1320 – 1325 –1382) * Sigismondo Polcastro (1384–1473) 15th–16th century * Nicolaus Copernicusº (1473–1543) 16th century and 16th–17th centuries * Gerolamo Cardano (1501–1576) * Tycho Brahe (1546–1601) * Giordano Bruno (1548– ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Scientists From Kyiv
A scientist is a person who conducts scientific research to advance knowledge in an area of the natural sciences. In classical antiquity, there was no real ancient analog of a modern scientist. Instead, philosophers engaged in the philosophical study of nature called natural philosophy, a precursor of natural science. Though Thales (circa 624-545 BC) was arguably the first scientist for describing how cosmic events may be seen as natural, not necessarily caused by gods,Frank N. Magill''The Ancient World: Dictionary of World Biography'', Volume 1 Routledge, 2003 it was not until the 19th century that the term ''scientist'' came into regular use after it was coined by the theologian, philosopher, and historian of science William Whewell in 1833. In modern times, many scientists have advanced degrees in an area of science and pursue careers in various sectors of the economy such as academia, industry, government, and nonprofit environments.'''' History The roles ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
1985 Deaths
The year 1985 was designated as the International Youth Year by the United Nations. Events January * January 1 ** The Internet's Domain Name System is created. ** Greenland withdraws from the European Economic Community as a result of a new agreement on fishing rights. * January 7 – Japan Aerospace Exploration Agency launches ''Sakigake'', Japan's first interplanetary spacecraft and the first deep space probe to be launched by any country other than the United States or the Soviet Union. * January 15 – Tancredo Neves is elected president of Brazil by the Congress, ending the 21-year military rule. * January 20 – Ronald Reagan is privately sworn in for a second term as President of the United States. * January 27 – The Economic Cooperation Organization (ECO) is formed, in Tehran. * January 28 – The charity single record "We Are the World" is recorded by USA for Africa. February * February 4 – The border between Gibraltar and Spai ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
1917 Births
Events Below, the events of World War I have the "WWI" prefix. January * January 9 – WWI – Battle of Rafa: The last substantial Ottoman Army garrison on the Sinai Peninsula is captured by the Egyptian Expeditionary Force's Desert Column. * January 10 – Imperial Trans-Antarctic Expedition: Seven survivors of the Ross Sea party were rescued after being stranded for several months. * January 11 – Unknown saboteurs set off the Kingsland Explosion at Kingsland (modern-day Lyndhurst, New Jersey), one of the events leading to United States involvement in WWI. * January 16 – The Danish West Indies is sold to the United States for $25 million. * January 22 – WWI: United States President Woodrow Wilson calls for "peace without victory" in Germany. * January 25 ** WWI: British armed merchantman is sunk by mines off Lough Swilly (Ireland), with the loss of 354 of the 475 aboard. ** An anti- prostitution drive in San Francisco occurs, and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Institute Of Physics Of The National Academy Of Sciences Of Ukraine
The Institute of Physics (IOP) of the National Academy of Sciences of Ukraine ( uk, Інститут фізики Національної академії наук України) founded in 1926 is the oldest research institution of physical science within the academy. Being on the path of both infrastructure development and research diversification for more than 80 years, the institute has eventually originated five more specialized research institutions. Currently, the institute employs more than 300 researchers (together with two full members and eight corresponding members of the NASU) and around 200 peoples of supporting personnel. It has more than 20 scientific units (including the state-of-the-art Femtosecond Laser Complex) which are grouped around four research programs Traditionally, the institute is focused on fundamental research. At the same time, applied research on cryogenics, LC displays, laser systems, pyroelectric detectors, biophysics and plasma technologies s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polaron
A polaron is a quasiparticle used in condensed matter physics to understand the interactions between electrons and atoms in a solid material. The polaron concept was proposed by Lev Landau in 1933 and Solomon Pekar in 1946 to describe an electron moving in a dielectric crystal where the atoms displace from their equilibrium positions to effectively screen the charge of an electron, known as a phonon cloud. This lowers the electron mobility and increases the electron's effective mass. The general concept of a polaron has been extended to describe other interactions between the electrons and ions in metals that result in a bound state, or a lowering of energy compared to the non-interacting system. Major theoretical work has focused on solving Fröhlich and Holstein Hamiltonians. This is still an active field of research to find exact numerical solutions to the case of one or two electrons in a large crystal lattice, and to study the case of many interacting electrons. Experime ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polariton
In physics, polaritons are quasiparticles resulting from strong coupling of electromagnetic waves with an electric or magnetic dipole-carrying excitation. They are an expression of the common quantum phenomenon known as level repulsion, also known as the avoided crossing principle. Polaritons describe the crossing of the dispersion of light with any interacting resonance. To this extent polaritons can also be thought of as the new normal modes of a given material or structure arising from the strong coupling of the bare modes, which are the photon and the dipolar oscillation. The polariton is a bosonic quasiparticle, and should not be confused with the polaron (a fermionic quasiparticle), which is an electron plus an attached phonon cloud. Whenever the polariton picture is valid (i.e., when the weak coupling limit is an invalid approximation), the model of photons propagating freely in crystals is insufficient. A major feature of polaritons is a strong dependency of the propag ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vadim Lashkaryov
Vadim Evgenievich Lashkaryov (October 7, 1903 – December 1, 1974), a prominent Soviet experimental physicist, was born in Kyiv, to a family of a lawyer. He was an Academician of the National Academy of Sciences of Ukraine and is known for his fundamental contributions to physics of semiconductors. Career Lashkaryov graduated from the Kiev Institute for People Education (as the Taras Shevchenko National University of Kiev, Kiev University was termed at that time) in 1924. He started his research work on the diffraction of X-rays in the Kiev Polytechnic Institute and continued it in the newly established Institute of Physics of the Ukrainian Academy of Sciences. In 1928 he moved to Physical-Technical Institute in Leningrad (currently Ioffe Institute in St. Petersburg), where he performed first in the Soviet Union experiments on electron diffraction. After a forced stay in Archangelsk, where he taught physics in the local Medical Institute, Lashkaryov returned to Kiev in 1939, where ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electric Dipole Spin Resonance
Electric dipole spin resonance (EDSR) is a method to control the magnetic moments inside a material using quantum mechanical effects like the spin–orbit interaction. Mainly, EDSR allows to flip the orientation of the magnetic moments through the use of electromagnetic radiation at resonant frequencies. EDSR was first proposed by Emmanuel Rashba. Computer hardware employs the electron charge in transistors to process information and the electron magnetic moment or spin for magnetic storage devices. The emergent field of spintronics aims in unifying the operations of these subsystems. For achieving this goal, the electron spin should be operated by electric fields. EDSR allows to use the electric component of AC fields to manipulate both charge and spin. Introduction Free electrons possess electric charge e and magnetic moment \boldsymbol whose absolute value is about one Bohr magneton \mu_. The standard electron spin resonance, also known as electron paramagnetic resonance (EP ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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