Valence electron ionization dynamics of chromium by a photoelectron imaging technique: J+-dependent state and angular distribution.

The photoionization of Cr at excited states is investigated using a velocity-map photoelectron imaging technique. Benzene chromium carbonyl or bis(η(6)-benzene) chromium was used as a precursor for the generation of excited Cr atoms. The a (5)S2 → x (5)P°3 and a (5)D3 → y (5)D°2 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)((5)D)4s4p((1)P°) to 3d(4)4s((6)D(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.