Autoionisation resonances in the photoabsorption spectra of Ge I and Sn I

Abstract

We report new measurements in the photoabsorption spectra of Ge I and Sn I in the vacuum ultraviolet region. The spectra were recorded in the first order of a 1-metre vacuum spectrograph using synchrotron radiation as the background source of continuum. Autoionisation resonances above the first ionisation were observed which are identified as the 4s 4p31P1 and 5s5p31P1 levels in Ge I and Sn I respectively. Resonances due to excitation to these levels from thermally populatedms2mp23P0, 1, 2 levels in the ground states have also been observed. Single configuration Hartree-Fock calculations are reported for the 4s4p3 and 5s5p3 configurations for Ge I and Sn I. Fano parameterisation was used to determine the Resonance wavelengths, the line widths and the asymmetry or line shape parameters.