STUDIES OF REACTIONS OF SMALL TITANIUM-OXIDE CLUSTER CATIONS TOWARD OXYGEN AT THERMAL ENERGIES

Reactions of small titanium oxide cluster cations with oxygen are studied using a selected-ion drift tube operated at thermal energies, in conjunction with a laser vaporization source. Clusters of most compositions are observed to react rapidly with oxygen in the drift tube reactor, but a few of them display very inert behavior. The studies of size-selected oxide clusters indicate that the inert clusters belong to two series, namely, (TiO2)n+ (n greater-than-or-equal-to 3) and TiO3(TiO2)m+ (m greater-than-or-equal-to 1). Interestingly, reactions of the oxygen-poor clusters with the oxygen molecule are seen to yield products containing fewer titanium atoms, while the clusters with higher oxygen-to-titanium ratios undergo attachment of one or two oxygen atoms. The reaction patterns are interpreted in terms of the difference in the bonding structure of the clusters.