Absolute oscillator strengths for hydrogen sulphide: II. Ionic photofragmentation and photoionization in the valence shell continuum regions (10–60 eV)

Abstract

Absolute oscillator strengths (cross sections) of ionic photofragmentation and photoionization for hydrogen sulphide in the valence shell continuum regions have been determined using dipole (e,e+ion) coincidence spectroscopy (∼1 eV fwhm) at equivalent photon energies from the first ionization threshold to 60.2 eV. These have been determined from the recently published absolute photoabsorption oscillator strengths [Feng et al., Chem. Phys. 244 (1999) 127] together with the photoionization efficiency and ionic photofragmentation branching ratios obtained from time-of-flight mass spectra reported in the present work. Consideration of the presently reported data together with the photoelectron branching ratios for H 2S and ionization potentials obtained from previously reported photoelectron and dipole (e,2e) spectroscopies yields quantitative information on the breakdown pathways of H 2S following absorption of radiation in the VUV and soft X-ray regions. A new photofragmentation product (H 2 +) and the doubly charged molecular ion (H 2S 2+) from hydrogen sulphide have been found in the present work. Partial photoionization oscillator strengths for production of the four valence shell electronic states of H 2S + have also been derived from the molecular and dissociative partial photoionization oscillator strengths over the entire energy range up to 60.2 eV.