Quantitative studies of the photoabsorption of carbonyl sulphide in the valence-shell, S 2p, 2s and C 1s inner-shell regions (4-360 eV) by dipole electron impact spectroscopies

Electronic excitation spectra and absolute photoabsorption oscillator strengths (cross-sections) have been measured in the UV, VUV and soft X-ray energy regions for the valence- and inner- (S 2p, 2s, C 1s) shell photoabsorption of carbonyl sulphide (OCS) from 5 to 360 eV using low-resolution(similar to l eV fwhm) dipole (e,e) spectroscopy. The absolute oscillator strength scale has been determined using valence-shell TRK (i.e., S(0)) sum-rule normalization. The discrete structures, as well as the continuum structures, in the valence region also have been studied at high resolution(similar to 0.05 eV fwhm) from 4 to 32 eV. The presently reported high- and low-resolution absolute photoabsorption oscillator strengths are compared with previously published data (from the direct photoabsorption measurements) in those limited energy regions where such data exist. Evaluation of the S(-2) sum using the presently reported absolute differential photoabsorption oscillator strength data gives a static dipole polarizability for carbonyl sulphide in excellent agreement (within 2%) with previously reported polarizability values. Other dipole sums S(u) (u = -1, -3 to -6, -8, -10) and logarithmic dipole sums L(u) (u = -1 to -6) are also determined from the presently reported absolute differential photoabsorption oscillator strength data. (C) 2000 Elsevier Science B.V. All rights reserved.