PHOTOCHEMICAL PROCESSES ON TRANSITION-METAL ATOMS AND SMALL CLUSTERS

Reported here are the first results of a new approach to studying the chemistry of metal clusters. Bare metal atoms emd clusters complexed w ith one or two reactant molecules (either ethanol or propanol) are gen erated in an ion trap where they are excited with radiation from a tun eable infrared laser. Although a single photon of the latter is not su fficient to break a chemical bond, because the clusters spend approxim ate to 1 ms within the radiation field, they absorb 15-20 photons (1.5 -2 meV) which, in some cases, is sufficient to drive a chemical reacti on. The photofragment yields exhibit a pronounced dependence on laser wavelength and at least one infrared absorption feature has a peak cen tre close to that seen for alcohol molecules adsorbed on to the surfac es of metals and metal oxides.