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BIOGRAPHIES OF GREAT SCIENTISTS
Semyonov Nikolai Nikolaevich Biography of a scientist
Directory / Biographies of great scientists
Nikolai Nikolaevich Semenov was born on April 3 (15), 1896 in Saratov, in the family of Nikolai Alexandrovich and Elena Dmitrievna Semenov. After graduating from a real school in Samara in 1913, he entered the Faculty of Physics and Mathematics of St. Petersburg University, where, studying with the famous Russian physicist Abram Ioffe, he proved to be an active student. After graduating from the university in 1917, the year of the Russian Revolution, Nikolai was left to prepare for a professorship. Until the spring of 1918 he worked in Petrograd. Here is how the scientist himself wrote about that time in one of his autobiographies: “Being carried away by scientific work, I had little interest in politics and had a poor understanding of events. In the spring of 1918, I went on vacation to my parents in Samara, where the Czechoslovak coup found me. petty bourgeoisie to the Mensheviks and Socialist-Revolutionaries (as you know, who headed the Samara Komuch), I voluntarily joined the so-called people's army of the Samara "constituent assembly" in mid-July. I was appointed as a soldier in an artillery battery, where during the entire time of my stay in the "army" (which lasted about a month) I performed the duties of a horse-breeder. Of this month, I spent about three weeks at the front ... Taking advantage of the news of my father's grave condition (he soon died), in mid-August I managed to get a vacation in Samara, arranged for myself to be transferred to the newly formed Ufa battery and, without stopping in Ufa, drove (in September) directly to Tomsk, deserted in this way from white army. Tomsk at that time was the only university city in Siberia, and I went there, hoping to devote myself to scientific work again. Indeed, Professor Weinberg (now serving in Leningrad) immediately gave me the opportunity to work scientifically in the laboratories of the Technological Institute, and from December I also began to teach at the university at the Department of Physics (Professor Pospelov). During my stay in Tomsk, I did several small, but completely independent scientific works. I organized a permanent scientific seminar at the Technological Institute, and finally, on my own initiative, I directed the scientific work and scientific education of the circle of the most talented student youth. In September 1919, I was mobilized by Kolchak and ended up as a "lower rank" in the Tomsk Artillery Battalion, from where, thanks to the efforts of Professor Weinberg and mine, I was transferred (in October 1919) to the radiobattalists and immediately seconded from there to the Technological Institute, where I continued my scientific work. After the arrival of the Red Army in Tomsk (in December), at the request of the university, I was finally expelled from the radio battalion (already transferred to the Red troops) by order of the commandant of Tomsk. After that, I continued my scientific and teaching work until May 1920, when, at the invitation of the State Institute of Physics, Technology and Radiology, I moved to work in Petrograd. Semenov is appointed Deputy Director of the Petrograd Institute of Physics and Technology and Head of the Laboratory of Electronic Phenomena. In 1921, Semyonov married Maria Isidorovna Boreisha-Liverovskaya, a bright, talented woman. She was a well-known specialist in the field of Romance philology, worked at the Petrograd University at the department of V. M. Zhirmunsky, translated Dante. Maria Isidorovna was much older than Nikolai Nikolaevich and had four children. From the very beginning, this difficult marriage was overshadowed by a serious illness that befell his wife. She died in August 1923, having lived with Nikolai Nikolayevich for less than two years. His most difficult spiritual drama was softened and cured by the niece of Maria Isidorovna, Natalia Nikolaevna Burtseva. She became the wife of Semenov and the mother of their two children - Yuri and Lyudmila. At that difficult time, in collaboration with Peter Kapitsa, Semenov proposed a method for measuring the magnetic moment of an atom in a non-uniform magnetic field, describing the experimental process in an article that was published in 1922. This method was later successfully developed by Otto Stern and Walter Gerlach. Then Semenov returns to the problem of gas ionization, apparently the first scientific problem that interested him. While still a university student, he published his first paper, which dealt with collisions between electrons and molecules. Upon his return from Tomsk, Semenov engaged in deeper studies of dissociation and recombination processes, including the ionization potential of metals and salt vapors. The results of these and other studies are collected in the book "Chemistry of the Electron", which he wrote in 1927 in collaboration with two of his students. Semenov was also interested in the molecular aspects of the phenomena of adsorption and condensation of vapors on a solid surface. His studies revealed the relationship between the vapor density and the temperature of the condensation surface. In 1925, together with the famous theoretical physicist Yakov Frenkel, he developed a comprehensive theory of these phenomena. Another area of interest for Semenov at that time was the study of electric fields and phenomena associated with the passage of electric current through gases and solids. The scientist, in particular, studied the passage of electric current through gases, as well as the mechanism of breakdown of solid dielectrics (electrically inert substances) under the influence of an electric current. Based on this latest research, Semenov and Vladimir Fok, famous for his work in the field of quantum physics, developed the theory of thermal breakdown of dielectrics. This, in turn, prompted Semenov to carry out work that led to his first important contribution to the science of combustion - the creation of a theory of thermal explosion and combustion of gas mixtures. According to this theory, the heat released during a chemical reaction, under certain conditions, does not have time to be removed from the reaction zone and causes an increase in the temperature of the reactants, accelerating the reaction and leading to the release of even more heat. If the increase in the amount of heat is fast enough, then the reaction can end in an explosion. Shortly after finishing this work in 1928, Semyonov was appointed professor at the Leningrad Institute of Physics and Technology, where he helped organize the department of physics and mechanics and also introduced the teaching of physical chemistry. At his insistence and with the help of his colleagues interested in the development of physical chemistry, the laboratory of electron physics became in 1931 the Institute of Chemical Physics of the USSR Academy of Sciences, and Semenov became its first director. “In 1931, a new institute was created under my leadership, and I was able to staff it entirely with my students. In 1920, I already had a team of 1931 good, active scientists trained by me!The staff grew so rapidly in all the laboratories of the Physico-Technical Institute, and in many other institutes organized in the country at the turn of the twenties. One should not think that our 25-year-old scientific supervisors of those years were some kind of inferior people in science. No, in those years, the growth of knowledge and experience among talented young people was amazing. By this age, all of them already had several printed works, sometimes of significant pioneering significance on the scale of the entire world of science. These works were widely referred to in their writings by foreign scientists. In our laboratory, fundamental works were prepared on the theory of branched chemical chain reactions, the theory of thermal explosion, the thermal theory of breakdown of dielectrics, the theory of molecular beams, on the first application of mass spectroscopy in chemistry, and many others." In 1929, Semenov was elected a corresponding member of the USSR Academy of Sciences, and in 1932 he became an academician. By this time, Semenov was conducting in-depth studies of chain reactions. They are a series of self-initiating steps in a chemical reaction that, once started, continues until the last step is completed. Despite the fact that the German chemist Max Bodenstein first suggested the possibility of such reactions back in 1913, there was no theory explaining the stages of a chain reaction and showing its speed. The key to a chain reaction is the initial stage of the formation of a free radical - an atom or group of atoms that has a free (unpaired) electron and, as a result, is extremely chemically active. Once formed, it interacts with the molecule in such a way that a new free radical is formed as one of the reaction products. The newly formed free radical can then interact with another molecule, and the reaction continues until something stops the free radicals from forming their own kind, i.e., until chain termination occurs. A particularly important chain reaction is the branched chain reaction, discovered in 1923 by the physicists G. A. Kramers and J. A. Christiansen. In this reaction, free radicals not only regenerate active centers, but also actively multiply, creating new chains and forcing the reaction to go faster and faster. The actual course of the reaction depends on a number of external constraints, such as the size of the vessel in which it takes place. If the number of free radicals grows rapidly, then the reaction can lead to an explosion. In 1926, two students of Semenov observed this phenomenon for the first time while studying the oxidation of phosphorus vapor with water vapor. This reaction did not go the way it should according to the theories of chemical kinetics of the time. Semenov saw the reason for this discrepancy in the fact that they were dealing with the result of a branched chain reaction. But such an explanation was rejected by Max Bodenstein, then the recognized authority on chemical kinetics. For another two years, intensive study of this phenomenon by Semenov and Cyril N. Hinshelwood, who conducted his research in England independently of Semenov, continued, and after this period it became obvious that our scientist was right. In 1934, Semenov published the monograph "Chemical Kinetics and Chain Reactions", in which he proved that many chemical reactions, including the polymerization reaction, are carried out using the chain or branched chain reaction mechanism. In the following decades, Semyonov and other scientists who accepted his theory continued to work on clarifying the details of the chain reaction theory by analyzing relative experimental data, many of which were collected by his students and collaborators. Later, in 1954, his book "On Some Problems of Chemical Kinetics and Reactivity" was published, in which the scientist summarized the results of discoveries made by him over the years of work on his theory. Service with Kolchak in the light of subsequent Stalinist repressions, apparently, often kept Nikolai Nikolaevich in suspense. He did not know that in 1937 a "university" case about an allegedly existing "fascist-terrorist organization" was fabricated in Leningrad. This organization, along with well-known physicists (V. A. Fok, L. D. Landau, and others), was supposed to include the "conspirator" N. N. Semenov, but, fortunately, no arrest followed. During the war, Semyonov, like many famous Soviet scientists, was evacuated to Kazan. Here he works on problems related to combustion and explosion issues. In 1943, the scientist moved to Moscow, where, according to a government decree, the Institute of Chemical Physics was transferred. The Semenov Institute took an active part in the nascent Soviet nuclear project. At the end of the forties, Nikolai Nikolaevich was subjected to disgusting persecution when a group of scoundrels from science accused him of lack of patriotism, "complaining to foreigners", even plagiarism! Semenov was "saved" from the fate of Kapitsa by her involvement in uranium work - the "uranium shield" truly worked. In 1956, Semenov, together with Hinshelwood, was awarded the Nobel Prize in Chemistry "for research in the field of the mechanism of chemical reactions." In his Nobel lecture, Semenov reviewed his work on chain reactions: “The theory of a chain reaction opens up the possibility of getting closer to solving the main problem of theoretical chemistry - the relationship between the reactivity and structure of the particles that enter into the reaction ... It is hardly possible to enrich chemical technology or even achieve decisive success in biology without this knowledge ... It is necessary to unite the efforts of educated people of all countries and solve this most important problem in order to uncover the secrets of chemical and biological processes for the benefit of the peaceful development and well-being of mankind. After Semenov was appointed professor at Moscow State University in 1944, he continued to publish his work on various problems until the XNUMXs. His voluminous work on the oxidation of phosphorus vapor has not lost its relevance today, many years after its creation. During World War II, the Institute of Chemical Physics moved to Moscow. Many areas of research conducted there are directly related to Semenov's original scientific interests, although now they were carried out with the help of mass spectrometry and quantum mechanics. Even in the last years of his life, Semyonov, according to his colleagues, remained a science enthusiast, a creative person who was distinguished by overflowing energy. He was tall and thin, loved to hunt and work in the garden, was fond of architecture. One of the grandsons of A. Yu. Semenov, Doctor of Biological Sciences, recalls: "Grandfather Kolya often worked on weekends, so the whole family got together only for lunch or in the evening at a large revolving table. Grandfather loved company and a cheerful feast. Numerous friends, relatives and students often gathered for weekends or holidays - employees of the Institute of Chemical Physics created by him. Not having a good ear, grandfather, nevertheless, loved to sing. I remember how he sings the song "Oh, Samara-town ..." Grandfather often laughed - softly, but very contagious. Even more often he squinted and smiled through his mustache. Semyonov died on September 25, 1986 at the age of ninety. Author: Samin D.K.
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