Quantitative studies of the photoabsorption (4.5–488 eV) and photoionization (9–59.5 eV) of methyl iodide using dipole electron impact techniques

Abstract

Absolute oscillator strengths (cross sections) for the valence shell, I 4d, 4p, 4s and C 1s inner shell photoabsorption of CH 3I have been measured using low resolution (1 eV fwhm) dipole (e,e) spectroscopy in the equivalent photon energy range from 4.5 to 488 eV. In addition, high resolution (0.05–0.1 eV fwhm) dipole (e,e) spectroscopy has been used to study the absolute valence shell and I 4d inner shell photoabsorption spectra of CH 3I from 4 to 65 eV in more detail. The photoionization efficiency, ionic photofragmentation branching ratios and absolute partial oscillator strengths for molecular and dissociative photoionization have been determined for CH 3I by dipole (e,e+ion) spectroscopy from the first ionization threshold to 59.5 eV. The major pathways of the ionic dipole induced breakdown scheme have been predicted from these results. Estimates of the absolute electronic state partial oscillator strengths of CH 3I + from photoionization of CH 3I were derived from the dipole induced breakdown scheme and the molecular and dissociative photoionization partial oscillator strengths.