A study of the SO molecule with photoelectron spectroscopy using synchrotron radiation

Abstract

The SO molecule has been studied by photoelectron spectroscopy using vacuum ultraviolet radiation from a synchrotron as the photon source. Both constant ionic state (CIS) and photoelectron spectra have been recorded. Resonances which appear in the CIS spectra recorded for selected vibrational levels of SO+ X 2Π in the photon energy region hν=11.5–15.0 eV have been assigned to excitations to Rydberg states which converge to the SO+ a 4Π and A 2Π states and autoionize to SO+ X 2Π. Also, resonances which appear in the CIS spectra recorded in the photon energy region 15.0–16.4 eV for selected vibrational levels of SO+ b 4Σ− have been assigned to excitations to Rydberg states which converge to SO+ B 2Σ− and autoionize to SO+ b 4Σ−. Photoelectron spectra recorded at selected resonant photon wavelengths show that autoionization can dramatically alter the intensities of the vibrational components in a photoelectron band and may allow extra vibrational structure to be observed. The additional information obtained from using this method to study short-lived molecules is discussed.