Abstract: | Positive and negative cluster ions in methanol have been examined using a direct fast atom bombardment (FAB) probe technique. Positive ion (CH3OH)IIH + clusters with n = 1-28 have been observed and their clusters are the dominant ions in the low-mass region. Cluster-ion reaction products (CH3OH)II(H2O)H+ and (CH3OH)II(CH3OCH3)H+ are observed for a wide range of n and the abundances of these ions decrease with increasing n. The negative ion (CH3OH)II(CH3O)? clusters are also readily observed with n = 0-24 and these form the most-abundant negative ion series at low n. The (CH3OH)II(CH2O)?, (CH3OH)II(HIIO)(CH2O)? and (CH3OH)II(H2OXCH3O)? cluster ions are formed and the abundances of these ions approach those of the (CH3OH)II(CH3O)? ion series at high n. Cluster-ion structures and energetics have been examined using semi-empirical molecular orbital methods. |