Fluorescence of Mercury Vapor.

Chr. Füchtbauer. Über eine neue Art der Erzeugung von Spektrallinien durch Einstrahlung (Fluoreszenz). Phys. Zeitschr. 21, 635 (1920).

When mercury vapor was illuminated with the light of a mercury arc, until now it had been possible to obtain only the so-called resonance radiation of the lines 253.7 and 184.9. The author of the paper under review, together with A. Kröner and G. Joos, succeeded in exciting in mercury vapor, when it was illuminated, the appearance of other lines not absorbed by mercury vapor in its ordinary state (fluorescence). This was achieved by increasing the energy of the exciting light. The exciting mercury lamp (quartz) had the form of a hollow cylinder, inside which a tube with mercury vapor (also quartz) could be placed. A branch of this inner tube, containing a drop of mercury, was immersed in water of the desired temperature. In this way it was possible to change the density of the mercury vapor inside the resonance tube. The resonance tube was closed at one end by a plane-parallel quartz plate, directed toward the slit of the spectrograph. To strengthen the exciting light, the mercury lamp was surrounded on the outside by a Palladinian glass jacket, into which mercury was poured, serving as a mirror. The lamp was fed with a current of 10–12 amp. The fluorescence spectrum was so bright that an exposure of 15 sec. was sufficient to obtain a clear image of seven lines on the photographic plate. The author exhaustively interprets the spectrum observed by him from the standpoint of Bohr’s theory.

S. Vavilov