Professor Ya. G. Dorfman addressed a letter to the editorial board of UFN in which he protests against the name “cyclotron resonance” for an effect predicted by him at one time.

This letter may create the impression that I alone—the author of a brief review article in UFN—insist on the indicated name, while most physicists either already call, or propose in the future to call, the effect by its original designation: “diamagnetic resonance.” It also follows from the letter that my statement that “the name originally given did not take hold” is my conjecture and that, in using the term “cyclotron resonance,” I am uncritically transferring American terminology into Soviet physical literature.

In reality the situation is not at all so simple. In the course of working on the article I thought a great deal about the terminology, and adopted the term “cyclotron resonance” not without hesitation. Nevertheless I did so and did not replace the new term by the old one during correction of the proofs, although I was also aware of Prof. Ya. G. Dorfman’s views on this question.

Strange as it may seem at first glance, the not very successful term “cyclotron resonance” has in fact become more widely used than the former designation “diamagnetic resonance,” above all among physicists engaged in the study of semiconductors and radiospectroscopy. Without referring to foreign data,* I should like to note that Soviet physicists—specialists in semiconductors for the effect under discussion—use only the former name and do not at all use the latter. Thus, at the All-Union Conference on Semiconductors (Leningrad, November 14–20, 1955), which brought together more than 1100 Soviet physicists and more than 50 scientists from the countries of the People’s Democracies, all speakers who touched in one connection or another on cyclotron-resonance absorption called it only by this term. This terminology was reflected in the official documents of the conference. In the resolution adopted at the final plenary session of the conference, in section 3 (on tasks in the field of semiconductor research), we read:

“g) preparation of investigations on paramagnetic, cyclotron, and other types of resonance phenomena in semiconductors...”

It should be noted that the conference and the work of the organizing committee were guided by Academician A. F. Ioffe, whom it is difficult to suspect of failing to understand the essence of physical phenomena in semiconductors or of careless handling of terminology. The author of these lines took part in the work of the conference organizing committee, but it can hardly be supposed that he inspired the use of unfortunate terminology in an official document adopted by a numerous and highly authoritative gathering of physicists.

Furthermore, the term “cyclotron resonance” is generally accepted in the plans of scientific institutions engaged in the study of semiconductors.

Thus, this term has become generally widespread among physicists and has been officially recognized as the only name for the given phenomenon.

Under these circumstances it would hardly have been appropriate if the author of the review had not noted that the name originally given did not take hold, and that the designation “cyclotron resonance” became more commonly used.

Of course, it was not only these formal considerations that compelled the author of the review to use a term that he himself does not consider successful.

The situation that has arisen with the name of the effect predicted by Prof. Ya. G. Dorfman did not arise by chance. In science it often happens that the terminology initially adopted by an author does not take hold. Thus, for example, the term “photomagnetic effect” once proposed (to denote magnetic resonance absorption) did not take hold in science, because another term was found that conveyed more precisely the physical essence of the phenomenon.

Can the term “diamagnetic resonance” be considered more successful than “cyclotron resonance”? In our view, this cannot be asserted.

The term “diamagnetic resonance” emphasizes the affiliation of the effect with the class of magnetic resonances. In reality, there are no serious grounds for considering it a variety of magnetic resonance. Magnetic resonant absorption of electromagnetic energy arises as a result of magnetic dipole transitions induced by the magnetic component of the radiation field acting on the substance. Cyclotron resonant absorption (let us call it that for the time being) is the result of di—

* For example, the materials of the Amsterdam Conference on Semiconductors (autumn 1954).

dipole electric transitions induced by the electric component of the same radiation field. There is no direct connection between this absorption and the diamagnetism of an ensemble of charges. The only thing that relates these two physical phenomena is the presence of a constant magnetic field, which forces the charges to move in circular orbits (in the simplest case) and thereby creates, on the one hand, the diamagnetic properties of the ensemble of charges and, on the other, a situation in which, by quantization of the orbital energy, absorption of the energy of the incident electromagnetic wave becomes possible through dipole electric transitions. The magnetic moments play no role here.

These considerations led the experimentalists not to call the new effect diamagnetic resonance, but to seek some other term. This term was indeed found from a comparison of the mechanism described above, that of resonance absorption, with the mechanism by which particles absorb energy in a cyclotron. These mechanisms are similar (more precisely, identical).

Of course, new effects should be named in accordance with their physical essence, and not after the instruments in which certain features of the given phenomenon appear. This is always observed, however. Of course, we do not call the Joule–Lenz effect “electric-kettle heating” or boiling “the samovar effect.” But we do call the frequency of revolution of a charge in a magnetic field the “cyclotron frequency,” and the fact of its independence from energy the “cyclotron principle,” and such terminology arouses no undesirable emotions among numerous listeners—physics students, with whom the author of these lines has constant contact.

Does this mean that I approve of all this “cyclotron” terminology? By no means. It seems to me most correct to name new physical phenomena after their authors, even if those phenomena have already acquired perfectly unobjectionable names. (Unfortunately, this good tradition has been increasingly lost in recent times.) In light of this, it would apparently be most correct to call the effect under discussion the Dorfman–Dingle effect*), after the physicists of whom the first predicted the effect and the second (a year later) repeated the prediction and gave the first outline of a theory. This would be all the more justified because the significance of the effect is in no way inferior to, for example, the Hall–Kikoin effect or the de Haas–van Alphen effect. In any case, the domain of its existence is wider.

V. N. Lazukin.

*) Incidentally, it should be noted that R. B. Dingle, in his recent papers, along with the term “diamagnetic resonance,” also uses the new term “cyclotron resonance.”