Photodissociation of Mg+-(CH3OH)N complexes: evidence for the onset of solvation

Mg+-(CH3OH)N complexes are produced in a molecular beam with a pulsed nozzle laser vaporization source and studied with mass-selected photodissociation spectroscopy. Resonance-enhanced photodissociation for Mg+-CH3OH produces a structured spectrum near 350 nm. Broad bands are assigned to vibronic structure in the 2Aseconds or inches and 2Aminutes or feet excited states near the region predicted by theory. Larger clusters for 1<N<6 exhibit efficient dissociation at 350 nm, proceeding via the elimination of solvent and the excited state photoinduced reaction to MgOH+-(CH3OH)MN=5 have no efficient photodissociation, indicating the loss of the Mg+ chromophore. Clusters in this size range bind water effectively while smaller ones do not, indicating stronger electrostatic interactions in the cluster. These observations imply that intracluster solvation to species of the form Mg2+,OH-(CH3OH)NCH3 or Mg2+,OCH3-(CH3OH)NH has taken place. (Copyright (c) 1998 Elsevier Science B.V., Amsterdam. All rights reserved.)