[London: Taylor & Francis], 1915. First edition.
Author’s presentation offprint, inscribed by Bohr to Prof. Biilmann, of this seminal paper in which Bohr introduced the concept of ‘stationary state’.
Soon after the completion of Bohr’s great trilogy on atomic constitution had appeared in November 1913, Moseley began to carry out experiments on X-ray spectra. Among other things, he found that the frequency of the Kα-line followed a Balmer-type formula similar to those which had inspired Bohr to develop his theory of atomic structure. In this paper Bohr attempts an explanation of this formula, refuting Moseley’s suggestion that the lines might be caused by several electrons jumping simultaneously (See Pais 182).
“Moseley was later killed in a war-related incident, a death that shocked Bohr and the entire scientific community.... coping with the calamity of his colleague’s death and the constant pressures created by the war, Bohr had to frequently revise and refine his atomic model in light of new discoveries. One significant paper, ‘On the Quantum Theory of Radiation and the Structure of the Atom,’ added more specific details about atomic states. For example, Bohr had earlier made the argument that electrons could jump from one orbit to another as energy was emitted or absorbed. In this paper, he theorized that an atom possesses stationary states in which energy was neither emitted nor absorbed. Any emission or absorption that did occur, such as might induce an electron to jump, would correspond to the transition between two stationary states.” (http://www.sparknotes.com/biography/bohr/section4.rhtml)
“Franck and Hertz unwittingly provided an independent confirmation of the concept of stationary state. In 1914 they observed an energy threshold in the electron-stopping power of mercury vapor. This threshold, Bohr explained the following year [in the present paper], corresponded to a transition between the normal state and another (first excited) stationary state of the mercury atom (and not, as Franck and Hertz had originally thought, to the ionization of the atom).” (http://content.cdlib.org/xtf/view?docId=ft4t1nb2gv&chunk.id=d0e5922&toc.depth=1&toc.id=d0e5922&brand=eschol).
Offprint from the Philosophical Magazine, vol. xxx, September 1915, pp. [i], 394-415 [1:blank], 8vo (222 x 145 mm), original printed orange wrappers, with inscription in Bohr's hand 'Hr. Prof. E. Biilmann // ærbødigst fra Forf.', with numbering to the upper left corner of the front wrapper, from the library of the Danish chemist Prof. Einar Biilmann (1873-1946).