Speaker
Description
Electron attachment by closed-shell species presents an interesting fundamental question: If an electron cannot be accommodated by an open valence, what attractive forces must be at play to allow for electron binding? Such attractive forces are non-valence interactions, which include electron attraction by a molecule’s dipole or quadrupole moment, polarizability, or electron correlation. Often anionic states that arise from these interactions are highly-excited states of anions, for which ground valence-bound states exist. However, an anion where electron binding can only persist through non-valence interactions is a matter worth exploring. Small xenon clusters provide an ideal test case for the study of non-valence bound systems, as the Xe$_N^-$ anions are purely correlation-bound. A Xe atom, alone, is unable to bind an electron, but due to xenon’s polarizability, an increase in electron attraction can occur with the addition of atoms to a cluster. Past experimental studies have substantiated the existence of these anions in the gas phase, and previous theoretical work has predicted the smallest bound Xe$_N$ cluster. However, the quantitative determination of the onset of electron attachment to Xe$_N$ clusters remains elusive. I have proposed investigating small Xe$_N^-$ clusters using velocity map imaging (VMI) spectroscopy with the exclusive utilization of the infrared output of the Fritz Haber Institute’s free electron laser for electron photodetachment. The electron binding energies (eBEs) of small xenon clusters are predicted to be in the meV range. Therefore, the combination of VMI and near threshold infrared photodetachment will allow for high resolution characterization of these anions. With these capabilities, it is not only possible to establish the lower bound for electron attachment to xenon clusters, but also determination of accurate eBEs and structural elucidation are within grasp. The pursuit of this work is expected to assist in verifying theoretical treatment of electron correlation, provide new information in the field of cluster evolution and aid in our understanding of non-valence bound anions.
