Photoelectron spectroscopy of reactive intermediates using synchrotron radiation

Abstract

Experiments performed with a purpose built spectrometer to study reactive intermediates with synchrotron radiation are described. Results are presented for some short-lived molecules of atmospheric and combustion importance. Constant ionic state (CIS) and photoelectron spectra were recorded. In each case, the observation of resonant structure in the CIS spectrum enabled the identification and characterization of Rydberg series associated with excited neutral states to be carried out. Examples of window resonances (SO) and possible competition between autoionization and predissociation (O2(a1Δg)) are encountered. Photoelectron spectra recorded at selected resonant energies exhibited extended vibrational structure, which led to improved estimates of ionic state spectroscopic parameters (ω-e$/, ω-e$/xe). Franck-Condon calculations for both CIS and PES data provided confirmation of resonant state assignments. Preliminary angular distribution measurements performed on O2(a14Δg) are presented, where the asymmetry parameter (β) showed structure at energies corresponding to neutral state resonances.