Multiphoton ionization of NO/CD3OH heteroclusters:: Observation of [(NO)n(CD3O)x(CD3OH)m]+ cluster ions

Ion-molecule reactions within heterogeneous NO/CD3OH cluster ions have been investigated through the use of multiphoton ionization time-of-flight mass spectrometry. For the case of the mixed cluster ions having two or more NO molecules, heterogeneous cluster ions of the form [(NO)(n)(CD3O)(x)(CD3OH)(m)](+), produced by multiple hydrogen atom loss, are observed. In contrast, the generation of [NO(CD3OH)(m)](+) is predominant in the mixed cluster ions containing one NO molecule. The hydrogen loss reaction proceeds up to x less than or equal to n-1 for [(NO)(n)(CD3O)(x)(CD3OH)(m)](+) with the generation of cluster ions possessing an even number of electrons being clearly preferred. These results lead us to conclude that the generation of cluster ions containing the CD3O species is strongly dependent on the electron configuration and the number of NO molecules in the cluster. Possible mechanisms of generating cluster ions having multiple CD3O species are discussed in terms of either a prompt multiphoton ionization or photochemical process prior to ionization. (C) 1999 American Institute of Physics. [S0021-9606(99)01312-4].