The vibrational analysis of the absorption spectrum of lead sulphide

Abstract

Band spectra due to the oxides of many elements are well known, but as yet little is known about the spectra of the sulphides of the same elements. Especially is this true of the sulphides of the metals, for up to the present only one, germanium sulphide, has been reported, A search for the absorption band spectra of the sulphides of the related elements, tin and lead, resulted in the discovery of two very extensive spectra, the first lying in the region λ 2600-λ 4500 and the second in the region λ 3100- λ 8000. A general description of these spectra has already been published. Both consist of overlapping progressions of bands degraded to the red. Raising the temperature of the absorbing vapour causes bands at the long wave-length ends of the spectra to be developed, the extent of the bands depending only on the maximum temperature used (for the same vapour-pressure). Lead sulphide bands in the region of greatest dispersion show apparently simple rotational structure. By analogy with PbO it would appear that the electronic transition is 1 ∑ ⟵ 1 ∑.