The photodetachment of the O 2 -·H 2O cluster anion at 780 and 390 nm is investigated in comparison with O 2 - using photoelectron imaging spectroscopy. Despite the pronounced shift in the photoelectron spectra, the monohydration has little effect on the photoelectron angular distributions: for a given wavelength and electron kinetic energy (eKE) range, the O 2 -·H 2O angular distributions are quantitatively similar to those for bare O 2 -. This observation confirms that the excess electron in O 2 -·H 2O retains the overall character of the 2pπ g* HOMO of O 2 -. The presence of H 2O does not affect significantly the partial wave composition of the photodetached electrons at a given eKE. An exception is observed for slow electrons, where O 2 -·H 2O exhibits a faster rise in the photodetachment signal with increasing eKE, as compared to O 2 -. The possible causes of this anomaly are (i) the long-range charge-dipole interaction between the departing electron and the neutral O 2·H 2O skeleton affecting the slow-electron dynamics; and (ii) the s wave contributions to the photodetachment, which are dipole-forbidden for π g -1 transitions in O 2 -, but formally allowed in O 2 -·H 2O due to lower symmetry of the cluster anion and the corresponding HOMO.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry