Zero electron kinetic energy and photoelectron spectroscopy of the XeI- anion

The XeI- anion and the corresponding neutral X1/2, I3/2, and II1/2 electronic states have been studied by means of zero electron kinetic energy (ZEKE) and photoelectron spectroscopy. The ZEKE spectra show rich and well-resolved progressions in the low-frequency vibrations of the anion and the neutral van der Waals complexes. From our spectroscopic data we construct model potentials for the anion and three neutral states, which are compared to previously obtained potential functions for this system. The intensity of the I3/2<--anion transitions relative to the X1/2 <--anion transitions in the XeI- ZEKE spectrum is considerably lower than expected from a Franck-Condon simulation based on the model potentials. Comparison with the photoelectron spectrum of XeI- indicates this is due to a small s-wave partial cross section for photodetachment to the I3/2 state. (C) 1998 American Institute of Physics. [S0021-9606(98)00148-2].