Valence Electron Ionization Dynamics of Chromium by a Photoelectron Imaging Technique: J(+)-Dependent State and Angular Distribution

Abstract

The photoionization of Cr at excited states is investigated using a velocity-map photoelectron imaging technique. Benzene chromium carbonyl or bis(eta(6)- benzene) chromium was used as a precursor for the generation of excited Cr atoms. The a S-5(2) -> x P-5(3)0 and a D-5(3) -> y D-5(2)0 transitions are then employed for the preparation of resonant intermediate states in a two-color two-photon ionization process, in which an electronic configurational change from 3d(4)(D-5)4s4p(1P(0)) to 3d(4)4s(D-6(J+)) occurs. The photoelectron kinetic energy distribution is found to be very sensitive to the ionization energy and the total angular momentum quantum number of the chromium ion (J(+)). Anisotropy parameters associated with departing electrons also show significant variation depending on the energy and total angular momentum quantum number, suggesting that direct and/or indirect ionization should be quantum mechanically mixed, manifesting the complicated nature of angular momentum couplings in the ionization continuum.