Bibliography

P. S. Tartakovsky, Experimental Foundations of Wave Matter, GTTI, Leningrad–Moscow, 1932, 150 pp., 59 figs., price 4 rubles, bound 5 rubles.

Physical theories go through the same cycle as living beings: childhood, youth, maturity, old age—and, incidentally, sometimes also rejuvenation. The wave theory of matter is rather the childhood name of the modern quantum theory, which embraces both matter and electromagnetic processes. But despite the fact that quantum theory is rather in its late youth, if not in mature age, the turbulent growth of it has not yet ceased. During the 6–7 years that have elapsed since the publication of the first papers of Heisenberg and Schrödinger, we have had a series of brilliant works that have applied the new quantum methods to the calculation of elementary physical phenomena in almost all fields of physics and physical chemistry. The success of this application is at the same time sufficient substantiation of the wave theory of matter. But its basis, in the proper sense of the word, may be called the experiments on the diffraction of material waves—the most graphic and popular proof of the existence of waves. It is precisely the diffraction of electrons to which Tartakovsky’s book is mainly devoted.

Undoubtedly, one must recognize as a happy idea the bringing together of the data scattered through many journals and relating to this comparatively narrowly restricted subject. First, despite the narrowness of this subject, up to the present time probably as many as a hundred, if not more, works have been devoted to it in various countries; reading a survey, especially if it is well compiled, considerably facilitates acquaintance with these numerous articles. This is all the more important since the diffraction of electrons, apart from its theoretical interest as the fundamental experiment of the wave theory of matter, is worthy of independent study.

A diffraction grating—a crystal—is, of course, by no means a simple physical instrument like an optical grating. Existing theories of electron diffraction that do not take into account the perturbing action of the electron on the periodically potential lattice are several simplifications, leading to an almost complete analogy with the dynamical theory of diffraction of X-rays, except for the fact that the mean internal potential of the lattice is introduced. It is therefore not surprising that a closer acquaintance with the diffraction of electrons in crystals brings us face to face with such riddles as half-integer and forbidden maxima, selective transparency of metals for slow electrons in the absence of a diffraction phenomenon upon reflection from the surface (Schliff), etc. In the development of the theory, these “unpleasant” facts will probably become the basis for understanding both the electronic structure of the lattice and the interactions between external and internal electrons.

In addition, electronography may be of considerable interest also in the structural analysis of matter, in the proper sense of the word, especially for polycrystalline bodies, colloids, etc. All this makes the monograph on electron diffraction very timely.

P. S. Tartakovsky’s book has been compiled carefully; the material is arranged in a good systematic order and is fairly complete, if one bears in mind that the book was completed at the beginning of 1932. It gives, in a very elementary form, an account of the theory of de Broglie and Schrödinger and of the diffraction of short waves (Chs. I, III), a survey of investigations on the scattering of electrons up to the wave—

mechanics (ch. II), a description of experiments on electron diffraction (chs. IV–VIII), a number of applications of diffraction (atomic factor), surface studies, etc. (chs. IX, X), practical information on experiment (ch. XI), a brief description of atom diffraction, and theoretical additions.

It is somewhat regrettable that the author did not consider it possible to acquaint readers more fully with the theories of Bethe and Morse. The connection of the latter with modern theories of electrical conductivity (Bloch), in which conduction electrons play the role of electrons of a cathode beam in electron diffraction, is obvious, and some deepening of the exposition in this direction would have made the booklet still more useful for the physicist experimenting in this field.

One could, of course, note a few unfortunate expressions or obscurities in the booklet (thus, on p. 64 it is said that the electron interferes with itself), but such points are isolated and do not diminish the general value of the book, which is undoubtedly useful and well written.

One wish to the publishing house: to print monographs of this type, in the nature of surveys, more quickly. Their significance lies in their timeliness, and they possess the property of aging to the highest degree.

S. Konobeevsky