On the spectra of the metals of the aluminium sub-group

Abstract

Continuing the previous work on absorption of light by thallium vapour, the author has now studied the absorption of T1 vapour from λ2400 to λ2000, and that of In from λ6000 to λ2000. The absorption tube was of steel, and provided with quartz windows at the ends, and absorption was studied with a quartz spectograph. Tables were given in each case of the wavelengths of the lines absorbed. The absorption spectra indicate marked similarities. The first members of the series, ¹π₂ - mδ', of both T1 and In, are found to exhibit assymmetrical absorption. In both cases there appear at high temperatures and on the short wave side of ¹π₂ - 2δ' a channelled space spectrum consisting of assymmetrical bands degraded towards the red. None of the lines of the principal series appeared in absorption, even at the highest temperatures used by the author. One remarkable feature is the very marked absorption of the members of ¹π₂ - mδ'.