...the classical theory of fluorescence and attempts, quite plausibly, to connect it with Shah’s theory. Namely, Curie assumes that, upon recombination, the electron returns not directly to the luminogenic atom, but to an ionized atom of the solvent, which is part of the luminogenic complex, and that the energy released in this recombination proceeds by impact to a luminogenic atom. Similar views had been expressed earlier by Tomaschek. This hypothesis makes understandable the experimental fact that one and the same luminogenic center, as calculation shows, can emit, when the phosphor is excited, from 2 to 4 quanta with one and the same emission spectrum.

However, even such a combined scheme of the emission process still does not seem sufficiently convincing in view of a number of experimental data. A way out of the difficulty, apparently, can be found only if one uses the images of wave mechanics. A sketch of such a theory was given not long ago by Blokhintsev.

All that has been said pertains mainly to the chapter—photoluminescence—which occupies 100 pages in Curie’s book. The remaining chapters, listed above, appear less interesting. There the author almost does not present his own personal considerations, but confines himself to an exposition of the material existing on the given questions. However, these chapters too are set forth very vividly and are written in an easy language.

The book is arranged quite satisfactorily and is supplied with a bibliography up to 1934.

B. Sveshnikov

A. REIMANN, Thermionic Emission, Chapman and Hall Ltd., London 1934, p. 324.

A. Reimann, Thermionic Emission.

In recent years a whole series of books devoted to electron emission has appeared in print. Even if one ignores the relatively old monograph by Richardson himself (1st edition—1916, 2nd edition—1921), then on this question we have, for the last period of time, the following books: 1) the monograph by Schottky and Rothe in Handbuch der Experimentalphysik, vol. XIII, part 2, 1928, 2) Deshman’s review from Reviews of Modern Physics for 1930, translated into Russian, 3) articles in the physics course of Müller—Pouillet, vol. IV, part 4, 1934, 4) Reimann’s book under review, 1934, 5) part 1 of Becker’s review in Reviews of Modern Physics for 1935, 6) de Boer’s monograph, 1935. The appearance of such a significant literature on this question is quite understandable, since electron emission is, on the one hand, the basis for the ever more developing and penetrating into the most diverse branches of technology electrovacuum industry, and, on the other, it is a node for the solution of a whole series of important theoretical problems, primarily those connected with the physics of surface phenomena. Being an object of study in numerous laboratories, in particular factory laboratories, and having recently undergone considerable theoretical restructuring thanks to the application of the methods of quantum statistics and wave mechanics, the question of electron emission has given rise to the appearance of such significant literature.

What place, then, does Reimann’s book under review occupy in the above list? As is seen from the preface, the author set himself the aim of giving in it a critical contemporary survey of all works in this field in a form accessible for reading by various categories of readers, especially in its theoretical part. The book consists of 6 chapters:

I. General survey.
II. Electron emission of pure metals.
III. Electron emission of metals covered with films.
IV. Oxide cathodes.
V. Contemporary theory of electron emission.
VI. Ion emission.

Bibliography

At the end of each chapter there is a fairly detailed bibliographic guide to original works.

On looking through the book, one sees that, in general, the author has coped quite satisfactorily with the task he set himself. The book is written vividly and interestingly, roughly in the style of the well-known review by Dushman. A descriptive form of exposition predominates in it, in which experimental works are covered, and sometimes in considerable detail; thanks to this, a substantial factual material has been collected in the book. A number of passages in the book are read with considerable interest, such as, for example, the chapter on oxide cathodes, in whose field the author himself has a number of works, the question of the film cathode, etc. The theoretical questions are touched upon much more modestly in the book—they are scattered in small quantities in various places, and only some of them (for example, potential barriers) are examined in detail in Chapter V. The author’s idea of giving in Chapter I a general introductory survey of the given question, and only after that going more deeply into its separate areas, should also be recognized as successful.

Along with all this, it must be acknowledged that this book also has a number of shortcomings, in particular the following. Nowhere in the whole book is there even a single word about the study of processes on the cathode surface by means of electron optics, which, as is known, has yielded its most interesting results precisely in this field. Further, the form of presentation of the chapter on film cathodes may also somewhat satisfy the reader only incompletely, since here very few generalizations of the numerous experimental data are given; possibly it would have been expedient here to preface it with an introduction setting forth the general properties of adsorbed films and their influence on the contact properties of surfaces, etc. Further, the author, as a collaborator of a firm laboratory, should undoubtedly have saturated the book with material of a purely practical character, as we have, for example, in Pote’s article, from which it undoubtedly would have benefited considerably, etc. Finally, it should also be pointed out—and this can no longer be charged to the author—that although the book was published in 1934, some of the data presented in it are already out of date today, as, for example, the theory of processes in a thoriated cathode (Langmuir), the Schottky effect in film cathodes (Becker), the electrical properties of adsorbed films (Langmuir, de Boer), etc. It must be noted, however, that these shortcomings of the book in no way offset the positive features noted above, and therefore Reimann’s book can be fully recommended as an interesting monograph giving a fairly clear and complete picture of the present state of the question of electron emission.

N. D. Morgulis

New Books*

V. D. KUPARADZE. Fundamental Problems of the Mathematical Theory of Diffraction (steady-state processes). L.—M., ONTI—Main Editorial Office for General Technical Literature, 1935, 111 pp. with figures, 3,000 copies, 2 rubles.

Contents: Fundamental equations (Formulation of the problem of electromagnetic diffraction. Formulation of the problem of diffraction in elastic media. Uniqueness theorem. Principles of radiation). Method of curvilinear coordinates. Construction of Mathieu functions. Properties of Mathieu functions. Expansion of Mathieu-Hankel functions. Diffraction near an ellipse, etc. Constructive methods (Diffraction near a semi-infinite segment. Diffraction near an angle. Method of parabolic coordinates). Method of integral equa-

* Compiled by the Review-Bibliographic Department of ONTI