Dissociation pathways of sulfur dioxide clusters and mixed sulfur dioxide-water clusters

摘要

A reflectron-time-of-flight mass spectrometer (RTOFMS) coupled with a femtosecond multiphoton ionization technique is used to study the combined metastable and collision-induced dissociation of sulfur dioxide clusters and mixed sulfur dioxide-water clusters. From the dissociation patterns, the general structural arrangement of the clusters is clearly identified: (SO_2)_m~(centre dot +) clusters have a SO_2~(centre dot +) core solvated by SO_2 molecules; [SO(SO_2)_n]~(centre dot +) and [S(SO_2)_(n+1)]~(centre dot +) have a structure of SO~(centre dot +). (SO_2)_n and (SO)_2~(centre dot +), respectively. For [HSO_2(SO_2)]~+ clusters, the ion core is HSO_2~+. H_2SO_3~+ appears to have two isomeric structures: one HSO_2~+ centre dot H_2O, the other H_3O~+ centre dot SO_2.