Threshold photodetachment spectroscopy of C−5

Abstract

have obtained vibrationally resolved photoelectron spectra of G&-l1 at a resolution of about 100 cm- ‘. This resolution is comparable to the lowest vibrational frequencies for these clusters, and not all features in the spectra were cleanly resolved. In this Communication, we report a considerably higher resolution (6-10 cm-’ ) photodetachment study of C< using threshold photodetachment spectroscopy.*v9 We observe considerably more vibrational structure than in the CT photoelectron spectrum and obtain evidence for a low-lying excited electronic state of Cs. The threshold photodetachment spectrometer used in this study is described in detail elsewhere.89’0 A beam of cold anion carbon clusters is generated in a laser vaporization/pulsed molecular beam source and is massselected using time of flight. The cluster of interest is then photodetached using a excimer-pumped tunable dye laser operating at 20 Hz, and electrons with near zero kinetic energy (ZEKE) are collected as a function of photon enery. The selective detection of the ZEKE electrons is done using the method developed by Mtiller-Dethlefs