The spectrum of H 2 : The bands analogous to the orthohelium line spectrum.-Part II

Abstract

1. It will be recalled that all the bands in this group of band systems end on an electronic level with total quantum number 2, which does not combine with the ground level of H₂. For this and other reasons, we call them the bands analogous to the orthohelium line spectrum since the n = 2 level of that spectrum does not combine with the ground level of He. Since our former paper* was written a number of new facts have come to light bearing on this group of band systems. These will now be briefly described. § 2. The System formerly called 3³S → 2³S, now called 2³S' → 2³S. Important additions have been made to this band system which require a reconsideration of its structure. By making use of Poettker’s infra-red measurements Sandeman has found three bands with initial vibrational levels lower than those of any of the bands which we discovered. This makes it necessary to change the numbering of the initial vibrational levels which we gave. The progressions to which we assigned the initial vibrational numbers n' = 0, 1 and 2 should be n' = 2, 3 and 4 respectively. The 3 new bands found by Sandeman are the 0' → 0", 0' → 1" and I' → 1". The new additions made by Sandeman to our former Tables XIII and XIV are collected in Table I. The wave numbers are given, followed by Gale, Monk and Lee’s§ eye estimates of intensities, in brackets.