High resolution photoelectron spectra of carbon cluster anions and their monohydrides

The smaller carbon cluster anions, Cn- (n = 2-11), and their monohydrides, CnH- have been studied previously using anion photoelectron spectroscopy. In many cases, vibrational structure is obsd., but much of the structure remains hidden due to the resoln. typical to that method. Although anion ZEKE spectra are available for some of the carbon clusters (where some addnl. structure was seen), traditional ZEKE techniques cannot detect p-wave scatterers with reasonable efficiency. By using slow electron velocity-map imaging (SEVI) to detect photoelectrons near threshold, a considerable gain in resoln. is accomplished. We present our first results for these systems here, including some work on the odd monohydrides which has not been published previously. The addnl. features seen are accompanied by improved photoelectron angular distributions, whereas previous values were detd. only coarsely by rotation of detachment laser polarization, complementing the energetic information detd. by the radial distribution. [on SciFinder (R)]