Bibliography

H. S. Massey and E. H. S. Burhop, Electronic and Ionic Impact Phenomena, Oxford, 1952, 669 pp., 286 illustrations.

Massey and Burhop. Electronic and Ionic Collision Processes.

Mott and Massey, in the preface to the second edition of their well-known book The Theory of Atomic Collisions, reported in 1949 the forthcoming publication of the book under review by Massey and Burhop, which is, as it were, the second volume of a large monograph on collisions. However, it took three years before the completed book appeared. This is evidently explained by the difficulties experienced by English publishers. Massey and Burhop hint at these difficulties at the end of their preface. Massey and Burhop’s book differs from that of Mott and Massey both in content and in manner of presentation. The whole book by Massey and Burhop is devoted to questions of “old” atomic physics, i.e. atomic physics in the proper sense of the term (and not nuclear physics).

Theoretical questions are presented in qualitative form, without detailed derivations, but with a clear effort toward a visual interpretation of the physical meaning of theoretical relations. In addition, special attention is paid to the experimental side of the matter. The book brings together a large body of experimental data and gives brief descriptions of experimental methods.

The first chapter is the passage of electrons through a gas and the total effective cross section. This chapter discusses general questions connected with the determination of the total effective cross section and presents the results of experimental data for total effective cross sections.

It should be noted that the question of the finiteness of the total effective cross section is more complicated than is formulated on p. 4 (see, for example, L. A. Sena, Collisions of Electrons and Ions with Gas Atoms). It is not clear why this chapter gives a detailed, but uncritical, account with all the derivations of the distribution function of electrons in a gas according to Morse, Allis, and Lamar. This derivation takes into account only collisions of electrons with gas atoms and does not take into account the interaction of the electrons with one another, and therefore leads to greatly exaggerated deviations from the Maxwellian distribution.

The second chapter describes the methods and results of determining effective cross sections for the ionization and excitation of atoms by electron impacts. In this chapter a number of works by Soviet scientists are used (Rozhdestvenskii, Latyshev and Leipunskii, and others), but the Soviet data on cross sections for collisions of the second kind, obtained on the basis of the principle of detailed balance, are not given (DAN XVII, 245, 1937).

Chapter three is devoted to a very qualitative exposition of questions connected with the theory of electron collisions with atoms. As is well known, the theory of collisions of slow electrons with atoms has encountered serious difficulties. The book soberly assesses the reliability of the resul-

... obtained in this field of theory, and the need for further research is emphasized. Among the comparatively recent questions touched upon is the question of the limiting resolving power of the electron microscope from the standpoint of obtaining an image of an individual atom. However, in doing so, no interesting Soviet work is used.

The fourth chapter—collisions of electrons with molecules—contains very extensive and interesting material, comprehensively characterizing all the principal types of interaction of electrons with molecules. Here theoretical questions and experimental data relating to elastic and inelastic collisions of electrons with molecules are combined. The chapter ends with an exposition of the theory of the Luxembourg–Gorky effect in the propagation of radio waves, but without mentioning Gorky.

The contents of the fifth chapter are somewhat unexpected in this book. This chapter is devoted to the reflection and secondary emission of electrons by solid bodies. Obviously, the authors proceeded from the scheme of the book: collisions of electrons with bodies having a gradually more complicated structure—atom, molecule, and solid body. Secondary emission of electrons can indeed be considered, in a certain sense, as ionization of a solid by electron impact. In the exposition of secondary emission, much less attention is paid to theoretical questions than is usually done in the corresponding monographs. There are especially many references to the theory of secondary emission developed by Kadyshevich, and the advantages of this theory over Wooldridge’s theory are noted (see p. 318) in the question of the distribution of primary electrons by velocities. Also widely used is the well-known experimental work of Afanas’eva and Timofeev. However, on the whole, Soviet work on secondary emission is used insufficiently, and the priority of Soviet scientists in solving a number of essential problems of secondary emission is not noted. In particular, although there is a reference to one work by Vudynskii, his priority in developing experimental methods for the study of secondary emission of dielectrics is not noted.

The sixth chapter—electronic collisions associated with the emission of radiation. This includes, above all, ordinary radiative recombination with a positive ion. However, alongside ordinary recombination the chapter considers a number of more subtle effects involving neutral atoms and bremsstrahlung radiation. The authors rightly emphasize the insufficiency of experimental data on ordinary radiative recombination of electrons with ions.

The next three chapters are devoted to collisions between heavy particles—atoms and ions.

The voluminous seventh chapter examines very important collisions between atoms under gas-kinetic conditions. Here a general classification of the types of collisions is given, and then all the principal types of elastic and inelastic collisions between atoms are considered in sequence. At the same time, data are presented from experimental investigations carried out by the most diverse methods (the phenomenon of transfer, mobility, molecular beams, etc.), and the corresponding theoretical works are set forth. Questions connected with collisions of the second kind between atoms are expounded briefly but sufficiently clearly. The theory of ion rearrangement is set forth less distinctly. Soviet works are used in the chapter (Terenin, Prilezhaev, Kondrat’ev, Senya, and others), but in an insufficiently complete form.

The eighth chapter—the passage of a homogeneous beam of positive ions or atoms through a gas—presents an interesting summary of experimental data compared with theoretical results. Most of the data naturally relate to particles possessing rather high energies, since inelastic collisions involving heavy particles occur at much higher energies than for electrons.

The ninth chapter corresponds essentially to the fifth chapter and is devoted to collisions of positive ions and neutral atoms with the surface of a solid. At the beginning of the chapter, brief information is given on secondary electron emission caused by impacts of positive ions. As is well known, this effect plays an exceptionally important role in electronic discharges and has been known to us for a very long time. Nevertheless, one must agree with the authors of the book, who point to the wholly insufficient study of the phenomenon as a whole. Thus, the neutralization of positive ions on the surface of a solid and the ejection of electrons by metastable atoms have not been studied sufficiently. In the chapter, some space is devoted to cathode sputtering. Here, however, Soviet works on this question have not been used, and in this connection the “state of the theory of cathode sputtering” is presented somewhat one-sidedly. The chapter concludes with a discussion of selective adsorption and accommodation.

The last chapter concerns the recombination of ions with one another and with the participation of electrons. Here, in particular, the very important process of triple recombination is considered.

The brief supplements contain reference material and annotations of some works that appeared mainly during the preparation of the book for publication (1948–1951).

In particular, the work of Baroody is cited, which gave a simple formulation of Kadyševich’s theory, and the results of a microwave study of the deionization of a discharge gap are described. On the whole, Massey and Burhop’s book is of undoubted interest for physicists working not only in this field, but also for specialists in electrical discharge in gases, for radio physicists, and finally for astrophysicists. The book is at once a reference work and a serious monograph, raising a number of problems for further research.

The book deserves translation into Russian. In the translation, the remarks made above should be taken into account, and, first of all, the editor of the translation should ensure a fuller reflection of Soviet works.

V. A. Fabrikant