SUPEROXIDE PHOTOELECTRON ANGULAR DISTRIBUTIONS: VIBRATIONAL DEPENDENCE AS A CONSQUENCE OF BORN-OPPENHEIMER BEHAVIOR
Duzor, Matthew Van
Lewis, B. R.
MetadataShow full item record
Publisher:Ohio State University
For atomic anions the photoelectron angular distribution (PAD) is a signature of the bound excess electron wavefunction. However, even for relatively simple molecular anions the relationship between the detachment orbital and the PAD is more complicated. We demonstrate this with a series of near threshold photoelectron images for superoxide detachment, recorded over small photon energy increments. The highest occupied, $\pi_g$ orbital has a strong resemblance to an atomic d-orbital. Detachment from the superoxide anion via the O_2$(X ^3 \Sigma_g^-$, v^\prime$)$ $\leftarrow $O_2^- $(X ^2\Pi_g$, v^\prime^\prime = 0)$ transitions reveals that the electron kinetic energy dependence of the PAD resembles that of atomic anions. However, there is also a clear dependence on the vibrational energy deposited in the neutral O_2$. Comparison with theoretical calculations reveals that this dependence is not due to non-adiabatic effects. Instead it arises in the change of the electronic transition moment across the X$-$X band, a direct consequence of the parametric dependence of the $\pi_g$ orbital function on the internuclear separation.
Author Institution: Department of Chemistry, Washington University, One Brookings Dr., Campus Box 1134 Saint Louis, Missouri 63130, USA; Research School of Physical Sciences and Engineering, The Australian National University, Canberra, Australian Capital Territory 0200, Australia
Items in Knowledge Bank are protected by copyright, with all rights reserved, unless otherwise indicated.