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Three definitive experiments designed to detect methanethiol dissociative adsorption on the clean Ag(110) surface shows that the S-H bond of adsorbed methanethiol does not dissociate on the clean Ag(110) surface and that methanethiol cleanly desorbs from the surface. These results are of importance in understanding the self-assembly of alkanethiol layers on silver where it has been commonly assumed that S-H bond scission occurs at room temperature.

An ion-molecule reaction has been observed from a condensed molecular crystal of CD3I using the time-of-flight electron-stimulated desorption ion angular distribution technique. The CD3I multilayer is produced by growth on an ordered substrate. The reaction occurs between CD3+ ions produced by electron- stimulated desorption and neighbor CD3I molecules in the topmost layer of the molecular crystal of CD3I, forming product C2D5+ ions whose desorption dynamics have been measured. The normal momentum of the product ion is close to that of the reactant ion, suggesting that the reaction is dominated by a two-body collision, i.e., the momentum of the reactant CD3+ ion governs the momentum of the product C2D5+ ion. The ion-molecule reaction is of high cross section since the C2D5+ yield is comparable to the CD3+ yield. It is found that the yield and directionality of the emission of the C2D5+ product ion is governed by the molecular order that is characteristic of the molecular crystal of CD3I. Destroying or modifying this order by using a spacer layer of H2O diminishes the C2D5+ product ion yield relative to the reactant CD3+ yield and broadens the ion emission directions. [ABSTRACT FROM AUTHOR]

An ion-molecule reaction has been observed from a condensed molecular crystal of CD(3)I using the time-of-flight electron-stimulated desorption ion angular distribution technique. The CD(3)I multilayer is produced by growth on an ordered substrate. The reaction occurs between CD(3)(+) ions produced by electron-stimulated desorption and neighbor CD(3)I molecules in the topmost layer of the molecular crystal of CD(3)I, forming product C(2)D(5)(+) ions whose desorption dynamics have been measured. The normal momentum of the product ion is close to that of the reactant ion, suggesting that the reaction is dominated by a two-body collision, i.e., the momentum of the reactant CD(3)(+) ion governs the momentum of the product C(2)D(5)(+) ion. The ion-molecule reaction is of high cross section since the C(2)D(5)(+) yield is comparable to the CD(3)(+) yield. It is found that the yield and directionality of the emission of the C(2)D(5)(+) product ion is governed by the molecular order that is characteristic of the molecular crystal of CD(3)I. Destroying or modifying this order by using a spacer layer of H(2)O diminishes the C(2)D(5)(+) product ion yield relative to the reactant CD(3)(+) yield and broadens the ion emission directions.

An ion-molecule reaction has been studied by measuring the momentum of both the reactant and the product ions. This is carried out in an ordered molecular film of CD3I where electron stimulated desorption causes the reaction CD+3+ CD3I--> C2D+5+DI. The close similarity of the normal momentum of CD+3 and C2D+5 indicates that a sticky collision occurs in which, to within 10%, the momentum of the reactant ion is transferred to the momentum of the product ion. The measurement represents the first use of molecularly aligned species to study momentum effects in an ion-molecule reaction.