The identification of 'optically forbidden' autoionising levels of zinc

In a recent study of the ejected-electron spectrum of zinc vapour following excitation by electron impact (see Back et al. (1981)), a number of lines were reported which could not be attributed to the autoionisation of known Zn I levels, viz. levels which had been excited in photoabsorption experiments. Most of the new lines are identified by comparison with ab initio Zn I calculations by the author. In the course of the analysis some anomalies encountered in previous comparisons between theory and photoabsorption measurements are explained. In particular the energy adopted for the Zn I 4p5s 1 P 1 level is changed significantly. Four Zn I configurations, 3d 9 4s 2 4p, 3d 10 4p5s, 3d 10 4p5p and 3d 10 4p4d are analysed in detail.