The Absorption of Radiation by multiply periodic Orbits, and its relation to the Correspondence Principle and the Rayleigh-Jeans Law. Part I- (II). (I. Some Extensions of the Correspondence Principle. - II. Calculation of Absorption by multiply period.

Corning, N.Y., and Menasha, Wisc., The Physical Review, 1924. Royal8vo. Full buckram. Gilt lettering to spine. A stamp to top of titlepage and to front free endpaper. In: "The Physical Review. A Journal of Experimental and theoretical Physics", Vol. 24, Second Series. V,704 pp., textillustr. Van Vleck's papers: pp. 330-346 a. pp. 347-365. Internally clean and fine. First appearance of Van Vleck's two importent papers in which he clarifies and extends the Principle of Correspondence."Van Vleck made his greatest contribution to the old quantum theory in 1924, when he conceived his correspondence principle for absorption. He demonstrated that in the limit of high quantum numbers there would be a correspondence between absorption by classical, multiply periodic systems, and by their quantum analogues. His proof depended on interpreting net absorption in the quantum theory as the difference between gross absorption and stimulated emission of radiation (an interpretation prompted by a remark of Breit?s). Van Vleck was particularly pleased that his classical theory reproduced the quantum result without the need for stimulated emission, which he referred to as "negative absorption." (DSB)."Van Vleck?s theory of absorption by multiply periodic systems was consistent with the newly derived Kramers theory of dispersion, and it convinced Bohr that his correspondence principle applied not only to emission but also to absorption. Further, Van Vleck?s 1924 calculation made use of several of the ideas that Werner Heisenberg used in his matrix mechanics a year later. Van Vleck?s work, however, did not lead in the direction of matrix mechanics. His intent was to explain quantum phenomena (especially "negative absorption") in classical terms rather than to devise an internally consistent quantum theory." (DSB).In 1977 he shared the Nobel Prize with Philip Anderson and N. F. Mott.Van der Waerden "Sources of Quantum Mechanics", pp. 203 ff.…