Angle-resolved photoelectron spectroscopy of Cl2 as a function of photon energy from 18 to 70 eV

Abstract

Angle-resolved photoelectron spectroscopy using synchrotron radiation has been carried out on gaseous chlorine as a function of photon energy from 18 to 70 eV. From this data the partial cross sections and angular distribution parameter β have been derived for the first three orbitals. For the lone pair orbitals 2πg and 2πu, distinct minima are found in both the partial cross sections and β values in the region of photoelectron energies from 30 to 40 eV. Less well-defined minima are also seen in the case photoionization for the nonlone pair orbital 5σg. These features are believed related to the Cooper minimum that arises from an atomic 3p subshell. Calculations have also been carried out on the partial cross sections and β values using the multiple scattering Xα method. Comparison with experiment gives excellent qualitative agreement with regard to the ‘‘Cooper minimum.’’ The nature of the Cooper minimum in molecules and its usefulness in understanding photoelectron dynamics is discussed.