Infrared photodesorption of methanol molecules adsorbed on a Au4+ cluster

The infrared photodissociation of mass selected cluster-adsorbate complexes Au4+(CH3OH)m (m = 1–3) is studied in a Penning ion trap. Spectra are obtained by the excitation of vibrational modes of methanol, the desorption of neutral molecules and the detection of fragment ions by time-of-flight mass spectrometry. The photodissociation spectra are red-shifted with respect to the absorption of frequency of free methanol. The number of photons necessary for the desorption of the adsorbate molecules and the respective separation energies are estimated.