INFRARED PHOTODESORPTION OF METHANOL MOLECULES ADSORBED ON A AU-4(+) CLUSTER

The infrared photodissociation of mass selected cluster-adsorbate comp lexes Au-4(+)(CH3OH)(m) (m = 1-3) is studied in a Penning ion trap. Sp ectra are obtained by the excitation of vibrational modes of methanol, the desorption of neutral molecules and the detection of fragment ion s by time-of-flight mass spectrometry. The photodissociation spectra a re red-shifted with respect to the absorption frequency of free methan ol. The number of photons necessary for the desorption of the adsorbat e molecules and the respective separation energies are estimated.