Bands in the secondary spectrum of hydrogen

Abstract

Fulcher’s discovery of bands in the secondary spectrum of hydrogen at low pressures proved the starting point of a number of investigations, including those, based on the valuable tables of Merton and Barratt, which have been carried out in the University of St. Andrews. The application of the quantum theory to these bands has been discussed by one of us (H. S. A.), by Curtis, and in particular by Richardson who, partly in association with Tanaka, has added greatly to the number of known regularities and done much to bring them into line with the theory of band spectra. Nevertheless, apart from the Fulcher system, of which Richardson has recently given a very complete account, there remains a very large number of lines which have not yet been classified. One of the present writers (I. S.) has been engaged in a study of the secondary spectrum at higher pressures, and among the regularities which have been selected by this method is a band with head at 4582·58 A. U. and shading towards the violet, which has been described in a recent communication. This band yielded an initial moment of inertia agreeing closely with a value deduced from a static model of triatomic hydrogen, H 3 . This band has since been found to be one of a large number of similar bands which it will be the purpose of this paper to describe. We shall refer to it for convenience as “Band II A , a .”