Excitation of the 3p-subshell in chromium vapour

The absorption spectrum of CrI between 30 and 400 Å++ has been photographed. At least 17 discrete features have been recorded and all are attributed to excitation of the 3p-subshell, after comparison with Hartree-Fock calculations. Previous observations of photoabsorption in Mn vapour (Connerade, Mansfield & Martin 1976) have shown a close correspondence to exist between the atomic and metallic spectra. For Cr, however, no similar correspondence has been found and reasons for this difference are proposed. The observation of a prominent discrete spectrum has enabled the energy of a 3p ionization threshold to be determined with reasonable confidence.