Absolute oscillator strengths for photoabsorption and the molecular and dissociative photoionization of nitric oxide

Abstract

The absolute dipole oscillator strengths (cross sections) for the photoabsorption of NO, measured from 6–190 eV, are compared with a variety of other published measurements. In the 20–30 eV region the present photoabsorption data, determined by dipole (e,e) spectroscopy, are in excellent agreement with those reported by Gardner et al. using synchrotron radiation. At higher energies good agreement is obtained with data reported by Cole and Dexter out to 190 eV. Photoionization branching ratios and absolute dipole oscillator strengths for molecular single and double photoionization as well as for all dissociative photoionization channels are measured by dipole (e,e + ion) spectroscopy in the equivalent photon energy range up to 80 eV. The photoionization efficiency is also measured from threshold up to 60 eV. The ion time-of-flight mass spectra show clear evidence of processes leading to O + and also to N + with high fragment ion kinetic energies. Earlier determined photoelectron branching ratios are used together with the present photoabsorption and photoionization efficiency data to recalculate partial photoionization oscillator strengths for production of electronic states of NO +. Finally these partial oscillator strengths for production of electronic states of NO + are considered together with those for molecular and dissociative photoionization in an attempt to predict the quantitative dipole ionic breakdown pathways for the interaction of energetic radiation with NO below 60 eV.