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Semenov, Nikolaî Nikolaevich

SEMENOV, NIKOLAî NIKOLAEVICH

(b. Saratov, Russia, 15 April 1896, d. Moscow, Russia, 25 September 1986), molecular physics, physical chemistry, chemical physics.

Semenov is credited with the discovery of a new type of chemical process: the so-called branched chain reaction. He determined the mechanisms of chain processes and developed a general theory for them. Semenov also created theories of chain and thermal explosions and developed the understanding of flame spreading, detonation, and burning of explosives. His theoretical models foreshadowed the discovery of nuclear chain reactions. Together with his colleagues, Semenov made a considerable contribution to the realization of nuclear projects in the Soviet Union. In 1956, he became the first Soviet scientist to be awarded a Nobel Prize in Chemistry.

Early Life Semenov was born into a middle-class family: his father, Nikolai Aleksandrovich Semenov, served as a clerk in Saratov Appanage District. As a reward for his long service, he was granted a rank of state advisor and life nobleman. His mother, Elena Aleksandrovna (born Dmitrieva), was from a medical assistant’s family. In 1913 Nikolai Semenov graduated from a professional secondary school in Samara. He entered the Physical Department of the Physical-Mathematical Faculty of St. Petersburg in 1913. (The name was changed to Petrograd University in 1914). Semenov graduated with honors in 1917, on the eve of Bolshevik Revolution, and was immediately granted a bursary that allowed him to prepare for the title of professor.

During his second year of study at the university, he engaged in experimental scientific work under the direction of Abram F. Ioffe. He studied the electron impact ionization of atoms and molecules in gas discharges. In 1918 Semenov went on vacation to visit his parents, who were living in Samara, and found himself in the vortex of civil war. He served several months in the White Army, in the troops of Aleksandr Vasiliyevich Kolchak—the head of internal counterrevolution in Russia, who organized anti-Bolshevik government in Siberia and Far East in autumn of 1918.

Scientific Career During 1918–1920 he taught at Tomsk University and at the Tomsk Technological Institute (Siberia). In 1920 he received an invitation to continue his research from Ioffe, who had just been elected as a full member of the Academy of Sciences to come to Petrograd (known as Leningrad since 1924). Semenov became head of the Electronic Phenomena Laboratory of the Petrograd Physical-Technical Radiological Institute. Beginning in 1927 he directed the Physical-Chemical Sector of the Institute. In 1931 on its basis there was established the Institute of Chemical Physics (Institut khimicheskoî fiziki, IKhF, Leningrad, after 1943 located in Moscow). Semenov headed it for some fifty-five years. The major mission of the institute was to introduce physical theories and methods to academic chemistry and to the chemical industry. In 1929 Semenov was elected a corresponding member of the Academy of Sciences (AS) of the USSR; in 1932 he became a full member of the AS. Having become a member of USSR AS Presidium (in 1957), Semenov held from 1957–1963 the position of secretary of its Department of Chemical Sciences and in 1963–1971 served as USSR AS vice-president. In 1963 he organized the Section of Chemical-Technological and Biological Sciences within the academy. In the Moscow suburb of Chernogolovka he established in 1955 a division of the IKhF that played an important role in the development of the Noginsk Scientific Center of USSR AS, a large complex of institutes. Several years later he founded within that center the Institute of New Chemical Problems. These reorganizations within the academy’s framework made it possible to concentrate the attention of scientists on the solution of scientific tasks necessary for the development of the country’s economy.

During all his life Semenov gave much attention to the training of new specialists. In 1920–1931 he taught in Petrograd (Leningrad) Polytechnic Institute, after 1928 as professor, and later as the dean’s deputy (1929) and the dean of the Physical-Mechanical Faculty of the Polytechnic Institute. In 1944 he became a professor at Moscow State University, at the Chemical Faculty, where he organized the Chair of Chemical Kinetics, remaining its head until the end of his life. Semenov also taught at the Moscow Mechanical Institute of Ammunition (later Moscow Engineer-Physical Institute), where in 1951 he founded and headed the Chair of Physics of Fast-proceeding Processes (1951–1957). He was also one of initiators and organizers of the Moscow Physical-Technical Institute (1951). Semenov created his own scientific school, having trained a brilliant pleiad of scholars, including V. V. Voevodskiî, V. I. Gol’danskiî, N. S. Enikopolov, Ia. B. Zel’dovich, D. G. Knorre, V. N. Kondrat’ev, M. A. Sadovskiî, Iu. B. Khariton, A. I. Shal’nikov, A. E. Shilov,N. M.Emanu!e’ (all of whom became full members of USSR AS); A. B. Nalbandian (full member of Armenian SSR AS); A. F. Walther, F. I. Dubovitskii, A. A. Koval'skiî,K. I. Shchelkin (USSR AS corresponding members); and others.

Semenov gave a good deal of attention to communication within the scientific physical-chemical community. He actively participated in holding scientific conferences (in particular, as an active organizer of the First Physical-Chemical Conference in the USSR held in 1927), and was an initiator of the establishment of Zhurnal fisicheskoi khimiî (Journal of physical chemistry; 1930) and the journal Khimicheskaia fizika(Chemical physics; 1981). With his direct assistance, a number of new educational establishments and research institutes were organized in the Soviet Union.

The Creative Path Having returned to Petrograd in 1918, Semenov worked on problems in molecular physics and studied the nature of electronic phenomena. He focused his attention on the processes of molecular dissociation under the action of electron impact, and he studied changes in the reactivity of atoms and molecules as a function of their electron excitation. This work laid the groundwork for the molecular beam methods that later became widespread in chemical physics. He researched the interaction of molecular beams of metal atoms with a chemically inert surface, which led to a model for the dependence of two-dimensional gas condensation on the temperature of the condensation surface. In 1925 Semenov, in collaboration with the theoretical physicist Iakov Frenkel, worked out a universal theory of this phenomenon.

Another sphere of Semenov’s interest in 1920s was the research of electric fields. He developed two new methods of experimental research of electrostatic fields (1920–1924), which were applied to a number of technically important cases (high-voltage isolators, cables and cable joints, and others). Studying the nature of electric breakdown of dielectrics in collaboration with A. F. Walther and L. D. Inge (1925–1929), he discovered the phenomenon of thermal dielectric breakdown (see Die physikalischen Grundlagen der elektrischen Festigkeitlehre, 1928; Teoriia i praktika proboia dielektrikov, 1929). His research on what appeared to be purely physical problems later led Semenov to develop a thermal theory of spontaneous ignition of a combustible gas.

Creation of a Theory of Chain Reactions The results of experiments carried out in Semenov’s laboratory in 1926–1927 heightened his interest in chemistry. One of the reactions under study was the vapor phase oxidation of phosphorus. The rate of reaction was observed to be marked by unexpected discontinuities. He discovered critical phenomena, consisting in sudden change from an almost absence of reaction to great increases in rate, these abrupt changes were in response to only slight changes in reaction conditions. For example, it was determined that at low pressures the reaction does not proceed at all. But when the pressure of oxygen was increased, at a certain point the combination reaction with phosphorus vapor occurs with ignition. Experiments showed the existence of a lowest limit of oxygen pressure, below which the reaction is very slow, but above which it runs quite rapidly, eventually resulting in the ignition of the mixture of reacting substances. Experiments with inert gas admixtures produced unexpected results. For example, the addition of argon caused ignition at pressures below the critical value observed in the absence of added argon. To explain such critical phenomena, Semenov put forward the idea of branched chain reactions, the theory of which he formulated for the first time in 1930–1934 and showed its wide occurrence. Experiments with oxidation reactions of sulfur vapor, hydrogen, carbon monoxide, carbon bisulfide, and other substances completely confirmed the results that were achieved in course of this work.

Semenov’s general theory of chain reactions eventually included consideration of both branched and unbranched chain processes. It represents a series of self-initiating stages of chemical reactions, which, once started, continue until the process halts for lack of reactant. The key to a chain reaction is an initial formation of a so-called active center—an atom or a group of atoms that has a free (unpaired) electron, that is, a free radical. Once formed, the free radical interacts with another molecule in such a way that a new free radical (continuation of chain) is formed as one of reaction’s products. The reaction continues until free radicals are somehow prevented from continuing to form similar particles (e.g., by destruction at the flask’s walls), that is, until a termination of the chain occurs. In a branched chain reaction, free radicals do not only regenerate active centers, but also actively multiply, creating new chains and constantly accelerating the reaction.

Semenov’s model was sufficiently general to explain many regularities of chain processes even without an identification of the precise nature of the active centers. His theory of chain reactions gave an explanation of chemically unusual facts such as a sharp dependence of rate reaction on minor changes of pressure, the effects of the additions of inert gas or a dependence on the diameter of the reaction flask and the condition of its walls. Semenov did not confine the role of the reaction vessel walls to the break of chains. He considered that on solid surfaces there can also occur reactions of origination and branching of chains, and the appearance of free radicals that which initiate a volumetric chain reaction when entering the gas phase from the surface. He established that among chain processes there is prevalence of heterogeneous-homogeneous reactions that begin on the surface of the flask and then pass to the volume. Experiments by Semenov and his colleagues during 1928 and 1929 established the existence of upper and lower ranges of ignition, that is, pressures, above and below which the explosive character of reaction’s progress disappears.

According to the theory developed by Semenov, and independently by the English chemist Sir Cyril Norman Hinshelwood, the concentration of active centers in a chain reaction increases exponentially with time. If branching of the chain prevails over breaks, then the speed of the reaction progressively grows in time, and the reaction ends with an explosion. Such a process is characterized as an “isothermal explosion”; there is nearly no heat generation. The origin of the ignition (or chain explosion) in this case is a progressive increase of the number of active centers, and as a consequence, the rate of reaction grows. The existence of an upper range of ignition in this theory is connected with the formation of low-activity radicals or molecules due to “triple concussion” (stabilization of a low-activity radical by a third particle), a result of increasing the system’s pressure. A lower range of ignition is caused by an increasing possibility of the loss of active centers (radicals or atoms) on the flask walls (the lower the pressure and the smaller the flask’s diameter, the faster the wall is reached by active particles). Though Hinshelwood and his colleagues were satisfied by this variant of the theory, Semenov extended it considerably.

Semenov substantiated important peculiarities of conducting chain processes especially connected with the interaction of active centers between each other (a so-called interaction of chains). In 1930–1932 he showed that the cases when chain self-acceleration occurs over a long period of time without chain ignition happening are quite widespread (for example, for oxidation of hydrocarbons in gas and liquid phases). In such reactions quite substantial periods of induction are typical, sometimes reaching many minutes or even hours. Semenov called these processes reactions of “degenerate explosion.” Regularities of development of degenerate explosion reactions are similar to kinetics laws of usual chain ignition, but these processes are developed quite slowly. As a rule, such reactions cannot reach explosive speeds due to a burnout of the initial substances. In cases when these reactions terminate in an explosion, the latter turns out to be connected not with a progressive increase of the number of active centers, but with the predominance of heat generation speed over the rate of heat rejection from the zone of reaction. Slow behavior of acceleration processes of reactions is connected with existence of special kind of “degenerate bifurcation.” Active centers are formed as a result of comparatively rare processing reactions of labile molecular intermediate substances.

Academician A. F. Ioffe noted in 1932 that Semenov’s studies of chain reactions “have revised the classic study of rates of chemical reactions, [they] created basis of new kinetics” (Zapiska ob uchenykh trudakh N. N. Semenova, p. 242). The major theories of chain reactions were expounded by Semenov in his monograph Tsepnye reaktsii (1934; published in English as Chemical Kinetics and Chain Reactions, 1935). This fundamental work became a classic reference of the chemical physics literature.

The Development of Chain Theory While making experimental verification of the main postulates of chain reactions theory, Semenov began to think in terms of a chemical substantiation of the chain mechanism. Though in Chemical Kinetics and Chain Reactions numerous examples of chain mechanisms were mentioned, they were mostly more or less possible schemes. In 1934–1958 Semenov began a series of researches designed to more concretely define the mechanisms of elementary stages of complicated chain reactions. He developed concepts of the reactionary ability of active particles (atoms and radicals)—participators of this process. These ideas led to the creation of new physical methods of investigation that allowed him to begin the study of the active particles themselves (atoms and radicals), the existence of which in the end of 1930s could be only surmised.

In this connection Semenov completed a large cycle of works relating to the study of a model reaction of hydrogen oxidation. Experiments confirmed that up to 20 percent of the initial hydrogen converts to the atomic form in the course of reaction. Semenov and his collaborators, using special methods of research involving hydrogen flames, also discovered the free hydroxide radical, the concentration of which was found to reach rather large values. A bit later, in 1960, using electronic paramagnetic resonance, they managed to detect considerable quantities of oxygen atoms and also free hydroxide radicals in a rarefied hydrogen flame.

An important aspect of the research conducted by Semenov was establishing a quantitative link between the structure of reacting substances and their reactivity from the position of chemical kinetics. In his monograph titled O nekotorykh problemakh khimicheskoi kinetiki i reaktsionnoi sposobnosti (1954; published in English as Some Problems of Chemical Kinetics and Reactivity, 1958), he summarized experimental material on the chemical mechanisms of chain processes. It covered various radical reactions, including those with biradicals. Specific attention was paid to the competition between chain, molecular, and ionic reactions. Semenov also formulated a semi-quantitative theory of reactivity of free radicals, which was a generalization of a famous rule of Polanyi. The Polanyi-Semenov rule found broad application in the kinetics of radical reactions, especially in the analysis of complicated chain reactions with a large number of elementary stages. It is used for approximate estimates of activation energy values of any stage.

While researching the mechanisms of degenerate-branched reactions, Semenov also investigated processes of chain oxidation of hydrocarbons in liquid phase. These works had a large practical importance. By direct oxidation of natural and industrial hydrocarbon gases and by oxidation of liquid hydrocarbons and their mixtures (oil stock), it was possible to develop methods of production of aldehydes (in particular, formaldehyde), ketones, organic acids, peroxides, and compound esters, all of industrial importance.

By 1929, in the course of his research on chain processes, Semenov concluded that excited molecules, forming in exothermic elementary steps, can cause branched chains due to excitation energy. But there was no experimental confirmation of that for some time. In the early 1960s Semenov’s colleagues showed experimentally for the first time that many fluoridation reactions— in particular, hygrogen fluoridation—are typical chain reaction with energetic branching. During such reactions, products are formed in excited states. In the course of destruction they give rise to free radicals, initiating new chains of chemical transformations. The phenomena of energetic branching were reported as a discovery of Semenov in 1962; his colleagues followed up in 1976. The results served as a stimulus for creating chemical lasers, and the first such laser (on the basis of reaction of fluorine with hydrogen) was created in the Institute of Chemical Physics.

The Theory of Burning and Explosion Semenov and his school (1930–1950s) laid the foundation of the contemporary theory of burning and detonation of gas mixtures, explosives, and gunpowder. The theory of flame spreading, which received a wide international acknowledgment, a theory of detonation, and a theory of turbulent burning were developed in his institute. A quantitative theory of thermal explosion (the formation of thermal self-accelerating avalanche) was put forward by Semenov in 1928. In the following decade he developed a mathematical formulation for such types of spontaneous ignition. At the same time he established regularities of flame and explosive wave propagation. Thus, along with chain ignition, thermal spontaneous ignition (or thermal explosion) is possible in reactions. The cause of explosion in this case is that heat escaping in the course of the reaction does not have time to be distributed to the surrounding environment; a progressively increasing temperature continually accelerates the speed of the chemical process. Self-heating of the mixture and self-acceleration of the reaction lead to thermal auto-ignition (or explosion). The theory of thermal auto-ignition permits a calculation of the temperature of spontaneous inflammation, if the thermal characteristics of the flammable gas mixture (e.g., thermal conductivity) and the kinetics of burning reactions (rate constants, energy of activation) are known.

In addition to the laws of thermal explosion for simple types of reactions, Semenov and his colleagues determined regularities of explosion for autocatalytic reactions, established criteria of thermal explosion as a function of the time of chemical reaction and the time of thermal relaxation, reviewed thermal explosions for cases of convectional transmission, and solved many other theoretic problems concerning thermal explosion in gases. In the IkhF, under Semenov’s direction, a contemporary theory of detonation phenomena was also developed.

The Nuclear Project Being the author of a theory of branched chain reactions, burning, and explosions, Semenov perfectly understood the meaning of works on the uses of nuclear energy for peaceful and military purposes. Towards the end of 1930s classic researches on the kinetics of chain decay of uranium (Ia. B. Zel’dovich, Iu.

B. Khariton) were accomplished within IKhF. Simultaneously, pioneering estimations of early variants of thermonuclear weapons were conducted. V. N. Kondrat’ev, together with his colleagues, investigated functions of reaction excitation of light nuclei, which were of interest for the realization of nuclear explosions. By the end of 1940 Semenov made an effort to stimulate research in this direction. He addressed the corresponding department (Narkomnefteprom of USSR, to which the institute was subordinated at that time) with a request to support such research, noting the potential for creating a nuclear bomb, but the decision to begin such work was not made.

The beginning of World War II stimulated research on explosives considerably. At the end of 1945, Semenov again submitted to the government a proposal for research on the creation of a nuclear weapon to be carried out within his institute. He formulated a number of objectives that the IKhF could reach theoretically and experimentally by his own efforts, and through collaborations with employees from other organizations. By a Resolution of the USSR Council of Ministers of 9 April 1946, the Institute was charged with the development of a nuclear weapon. IKhF was commissioned to perform calculations connected with the construction of atomic bombs, measurements of necessary constants, preparation of a training ground, and design of equipment for the assessment of the damage resulting from a nuclear weapon. A special sector, with a number of departments and laboratories, was established in the institute for implementation of this work.

Under Semenov’s direction, the institute made a substantial contribution to building the nuclear power of the Soviet Union, creating the scientific bases of exploding an atomic bomb and the principles of protection from it. Semenov was the originator of the electronuclear breeding method, which remains one of most promising and safest directions in nuclear power engineering. The first nuclear test was carried out (1949, Semipalatinsk) at a training ground prepared under the aegis of the institute.

Solutions in the Sphere of Catalysis Processes of homogeneous and heterogeneous catalysis also came within the scope of Semenov’s scientific interest. As early as the 1930s, works on heterogeneous catalysis (S. Z. Roginskiî, then O. V. Krylov and others) were begun in the IKhF under Semenov’s direction. Starting from concepts of an electronic theory of catalysis that had been developed by S. Z. Roginskiî and F. F. Vol’kenshteîn (1948), Semenov, together with V. V. Voevodskii and F. F. Vol’kenshtein (1955), formulated a model for heterogeneous chain processes. Under Semenov’s guidance, research began in 1947 on a new type of catalysis: ionic-heterogeneous catalysis in thin films of acid. The mechanism of this catalysis was revealed, and the effectiveness of industrial catalysts of the acid type was substantially improved. In the 1970s at his initiative there began research in the USSR on the possibility of developing new fermentation catalytic processes that would be similar to photosynthesis or the fixation of nitrogen and which would utilize solar energy.

At his initiative, research on application of major approaches of fermention catalysis to the elaboration of new catalytic processes with the usage of solar energy (similar to photosynthesis, fixation of nitrogen) opened in the 1970s. It was at this time that Semenov called attention of his scholars to the problems of searching new ways of conducting purely chemical reaction on the principle of biochemical processes, occurring in live organisms. Semenov considered the solution of this problem, which also relates to photochemical usage of solar energy, as a very important area in the future of chemistry.

Awards and Honors Semenov’s contribution to the development of science was honored, in addition to the Nobel Prize (shared with Hinshelwood), with state prizes: he was twice Hero of Socialist Labor (1966 and 1976) and the recipient of Lenin (1976) and State (Stalin) Prizes (1941 and 1949), and was awarded the order of Labor Red Banner (1946) and the order of the October Revolution (1986). He was awarded seven Lenin Orders (1945, 1953, 1956, 1966, 1971, 1976, 1981), the minor D. I. Mendeleev Prize (USSR AS 1936), and eleven medals.

Semenov’s works have received a distinguished assessment in the world. He was elected an honorary member of foreign academies and scientific societies of England, India, Hungary, the United States, Romania, Czechoslovakia, Bulgaria, and was a foreign member of six academies (United States, Czechoslovakia, GDR, Bulgaria, Poland, and France) and of the Royal Society of London (1958). Semenov was granted the title Dr. Honorius Causa by universities of the following cities: Oxford, Brussels, Milan, Budapest, London, Prague, Berlin, and Wroc aw.

Semenov was married three times: in 1921 to Mariia Isidorovna Boreîsha-Liverovskaia, who died in 1923; in 1924 to Natal’ia Nikolaevna Burtseva (this marriage led to the birth of a son, Iuriî, and a daughter, Liudmila); and after their divorce, to Shcherbakova Lidiia Grigor’evna in 1971.

BIBLIOGRAPHY

Semenov’s creative and scientific heritage, correspondence, and other documents are located in the RAS Archive. In 1989, with a view of preservation and preparation for the publication of archive documents and other materials, the Resolution of USSR AS Presidium established the Commission for Semenov’s Scientific Heritage (chairman-academician Aleksandr E. Shilov; deputy chairman-professor Gleb B. Sergeev). A full list of works by Semenov is published in the book Nikola î Nikolaevich Semenov, 1896–1986. Materialy k biobibliografii uchenykh SSSR, 3rd ed. Moscow: Nauka, 1990 (see Other Sources). Executive editors Aleksandr E. Shilov and Gleb. B. Sergeev with the assistance of Russian Foundation for Basic Research published his selected works in 4 volumes: Semenov N.N. Izbrannye trudy (Selected works). Moscow: Nauka, 2004–2006.

WORKS BY SEMENOV

“K teorii protsessov goreniia. Soobshchenie 1” (To the theory of burning processes. 1st report). Zhurnal Russkogo Fizikokhimicheskogo obshchestva (Journal of Russian Physical-Chemical Society) 60, no. 3, (1928): 247–250.

“Zur Theorie des Verbrennungsprozesses.” Zeitschrift f. Physikalische Chemie 48, no. 8, (1928): 571–582.

With A. Walther. Die physikalischen Grundlagen der elektrischen Festigkeitlehre. Berlin: Springer, 1928.

With S. M. Bragin and A. F. Walther. Teoriia i praktika proboia dielektrikov (Theory and practice of dielectric breakdown). Moscow and Leningrad: Gosizdat, 1929.

Sovremennoe uchenie o skorosti gazovykh khimicheskikh reaktsiî(Contemporary studies of speed of gas chemical reactions). Moscow and Leningrad: Gosizdat, 1929.

“Tsepnye reaktsii” (Chain reactions). Uspekhi fizicheskikh nauk(Progress of physical sciences) 10, no. 3 (1930): 347–365.

“Gazovye vzryvy i teoriia tsepnykh reaktsiî” (Gas explosions and theory of chain reactions). Uspekhi fizicheskikh nauk(Progress of physical sciences) 1, no. 2 (1931): 250–275.

“Tsepnaia teoriia i okislitel’nye protsessy” (Chain theory and oxidation processes). Uspekhi khimii(Progress of chemistry) 2, no. 5 (1933): 590–621.

Tsepnye reaktsii (Chain reactions). Leningrad: ONTI-Gosizdat,1934; 2nd ed., revised and complemented. Moscow: Nauka, 1986.

Chemical Kinetics and Chain Reactions. London: Oxford University Press, 1935.

“Teplovaia teoriia goreniia i vzryvov. Vvedenie. Ch. 1, 2”(Thermal theory of burning and explosions. Introduction. Parts 1, 2). Uspekhi fizicheskikh nauk(Progress of physical sciences) 23, no. 3 (1940): 251–292; “Teplovaia teoriia goreniia i vzryvov. Vvedenie. Ch. 3” (Thermal theory of burning and explosions. Introduction. Part 3). Uspekhi fizicheskikh nauk(Progress of physical sciences) 24, no. 4 (1940): 433–486.

“K voprosu o trekh predelakh vosplameneniia” (To the issue of three ranges of inflammation). Doklady AN SSSR (USSR AS Reports) 81, no. 6 (1951): 645–648.

O nekotorykh problemakh khimicheskoî kinetiki i reaktsionnoî sposobnosti (Some problems in chemical kinetics and reactivity). Moscow: Izdatel'stvo AN SSSR, 1954, 2nd ed.; Moscow: Izdatel'stvo AN SSSR, 1958.

Some Problems in Chemical Kinetics and Reactivity. Princeton, NJ: Princeton University Press, 1958.”

Energeticheskoe razvetvlenie tsepei “(Energy branching of chains). Vestnik AN SSSR (USSR AS Bulletin), 5 (1970): 38–48.

Khimicheskaia fizika (Chemical physics). Chernogolovka: Institut Chemicheskoi Fiziki AN SSSR, 1975; Moscow: Znanie, 1978.

Nauka i obshchestvo: stat’i i rechi (Science and society: Articles and speeches). Moscow: Nauka, 1981.

OTHER SOURCES

Dainton, F. S. “Nikolaî Nikolaevich Semenov (16 April 1896–25 Sept. 1986).” Biographical Memoirs of Fellows of the Royal Society London 36 (1990): 527–545.

Ioffe, Abram F. “Zapiska ob uchenykh trudakh N. N. Semenova”

(Notes on the scientific works of N. N. Semenov). In Khimiki o sebe (Chemists about themselves), complied by I. Solov’ev. Moscow: Vladmo UMIZ Graf-Press, 2001.

Khimichaskaia kinetika i tsepnye reaktsi: sbornik stateʾ. K 70-letiiu akademika N. N. Semenova (Chemical kinetics and chain reactions: Collected articles. For the seventieth anniversary of academician N. N. Semenov). Moscow: Nauka, 1966.

Kritsman, Viktor.A., Zaikov Gennadiî E., and Õmanuel NikolaîM. Chemical Kinetics and Chain Reactions: Historical Aspects. New York: Nova Science Publishers, 1995. The role of Semenov in the creation of chain reactions theory is described in detail, and an analysis of his work Chain Reactions is given.

Nikolaî Nikolaevich Semenov 1896–1986: Materialy k biobibliografii uchenykh SSSR (Materials for the bibliography of USSR scientists). Seriia khimicheskikh nauk; Vyp. 84, 3rd ed., revised and complemented. Moscow: Nauka, 1990.

Shilov, Aleksandr E., Gleb B. Sergeev, Lidiia G. Shcherbakova-Semenova, et al., compilers. Semenov, N. N.: Ia ne mysliu drugoî zhizni, kak zhizn’ vmeste s naukoî (Semenov, N. N.: I do not see any other life, but a life with science). Moscow: Konva, 2001. The book is for a wide readership and includes many documentary photographs. It is a bilingual edition (in Russian and English).

Solov’ev, Iuriî I., comp. Akademik Nikolaî Nikolaevich Semenov: Vitse-prezident Akademii Nauk SSSR(Academician Nikolaî Nikolaevich Semenov: The vice-president of USSR Academy of Sciences). Moscow: Vlladmo, UMIZ Graf-Press, 2002. The book includes archive materials (RAS Archive), characterizing the scientific and organizational activity of the scientist, including reports and appearances of Semenov at general meetings of USSR AS and of USSR AS Presidium (1957–1971), and documents concerning the organization of new scientific centers.

Vardugin, Vladimir I. Taîna ognia: Povest’ o N. N. Semenove(Mystery of the flame: Narrative about N. N. Semenov). Saratov: Privolzhskoe knizhnoe izdatel'stvo, 1986.

Vospominaniia ob akademike Nikolae Nikolaeviche Semenove(Reminiscences about academician Nikolaî Nikolaevich Semenov). Seriia “Uchenye Rossii. Ocherki, Vospominaniia, Materialy,” composed by N. V. Gorbunova, preface by Aleksandr E. Shilov. Moscow: Nauka, 1993. For a wide readership; Semenov’s colleagues, friends, and relatives tell about his life and activity.

Elena Zaitseva

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Nikolai Nikolaevich Semenov

Nikolai Nikolaevich Semenov

The Russian physicist and physical chemist Nikolai Nikolaevich Semenov (1896-1986) is famous for his experiments explaining chemical reactions by means of the mechanism of chain reactions.

Nikolai Semenov was born on April 15, 1896, in Saratov. He displayed a keen interest in the physical sciences by the time he was 16 and in 1913 entered the physics and mathematics department of the University of St. Petersburg (later Petrograd and now Leningrad). At the age of 20 he published his first paper on the collision of molecules and electrons. In 1917 he ended his studies at the University of Petrograd, obtained a position as physicist in the Siberian University of Tomsk and later, in 1920, returned to work for the next 11 years at the Petrograd (in 1924 Leningrad) Institute of Physics and Technology.

In 1928 Semenov became a professor at the Leningrad Polytechnical Institute and organized its physics and mathematics department. Three years later he was appointed scientific chief of the Institute of Physical Chemistry of the Soviet Academy of Sciences. In 1932 he was elected to full membership in the academy, and from 1957 to 1963 he was the academy's secretary of the division of the chemical sciences. In 1944 he was assigned to the University of Moscow, heading the department of chemical kinematics. He also was instrumental in launching scientific journals and organizing Soviet conferences on physical chemistry.

Semenov's scientific investigations dealt primarily with molecular physics and electronic phenomena, the mechanism of chemical transformations, and the propagation of explosive waves. He published in "The Oxidation of Phosphorus Vapor at Low Pressures" (1927) his discovery of branching reaction chains in chemical transformations having the character of an explosion. Semenov intensively continued his researches in chemical reactions involving the chain theory and published his results in Chemical Kinetics and Chain Reactions (1935) and in the exhaustive two-volume study Some Problems in Chemical Kinetics and Reactivity (1958-1959). For his contributions to reaction kinetics, Semenov was awarded the Nobel Prize in 1956, the first resident Soviet citizen to achieve this distinction.

Semenov also played an active role in his country's affairs. He first joined the Communist party of the Soviet Union in 1947, served as a deputy in the Supreme Soviet in 1958, 1962, and 1966, and in 1961 was elected an alternate member of the party's Central Committee. In the Soviet Union he fought for the liberty of experimentation for the scientist, freedom of expression for the artist, and "chain reactions of success" for humanity as a consequence of international scientific exchanges. In 1971, Semenov, along with thirteen other Soviet scientists, signed a cablegram letter to President Richard Nixon, expressing concern that the Federal murder trial of African American militant and philosophy teacher Angela Davis be conducted such that her life would be spared (she was a member of the Communist party). Nixon responded by inviting all the scientists to attend her trial. Semenov died in 1986.

Further Reading

Only scattered articles on Semenov have thus far appeared in English and Russian newspapers and journals. A brief biographical sketch of Semenov by Albert Parry is in George W. Simmonds, ed., Soviet Leaders (1967). Semenov's scientific contributions receive mention in the comprehensive work of V. N. Kondratev, Chemical Kinetics of Gas Reactions, translated by J. M. Crabtree and S. N. Carruthers (1964), and in Keith J. Laidler, Reaction Kinetics (1966). □

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