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≤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.