Pressure Effect on Predissociation

Abstract

THE absorption spectrum of S₂ vapour shows two regions of predissociation (marked by the diffuseness of the bands) which are known to extend over a considerable spectral range, including several bands belonging to different vibrational states. Using, however, an extremely low vapour pressure of sulphur—this may be obtained experimentally by heating carbon disulphide vapour in the absorbing cell up to about 500° C.—the previously diffuse bands appear sharp, with the exception of one band ( = 0, = 16) which is situated nearest to the predissociation limit and remains quite diffuse. (The spectrum extends only over a limited range; for this reason the first predissociation limit could not be observed.) The next following band ( = 0, = 17) shows a broad but well developed rotational fine structure.