Seminars Archive

Photoelectron spectroscopy of reactive intermediates with synchrotron radiation

Abstract
The work presented is a study of atmospherically important unstable species in the gas phase using photoelectron spectroscopy at the Elettra Synchrotron Source. Unstable species, including complexes and radicals, are currently receiving a great deal of attention from the chemistry community as a result of recent developments in experimental and theoretical methods. All of the chemical properties of molecules are a consequence of their electronic structure, in particular the nature of their valence electrons. The overall aim is to probe the electronic structure of reactive intermediates using photoelectron spectroscopy (PES), constant ionic state (CIS) and threshold photoelectron (TPE) techniques combined with angular distribution studies performed with linear polarised Synchrotron Radiation light. Examples of UV photoelectron spectroscopy studies of N and S atoms and CF and CF2 radicals are presented. In these experiments, autoionizing resonances have been observed and assigned to members of series of Rydberg states converging towards higher ionic limits. For example, for the first time Rydberg series converging to the fourth ionization limit of S atoms have been observed and assignments have been proposed after fitting the experimental spectra with lineshape formula based on multichannel quantum-defect theory (MQDT). These studies have highlighted the improvement in resolution that can be obtained using a third generation synchrotron, especially when constant ionic state measurements are performed.