Summary: Reactions of Boron Oxide and BnOmH+ Cluster Ions with Water
Adam Lapicki, Dilrukshi M. Peiris, Jason N. Smolanoff, and Scott L. Anderson*
Department of Chemistry, UniVersity of Utah, Salt Lake City, Utah 84112
ReceiVed: June 17, 1998; In Final Form: July 27, 1998
Reactions of BnOm
+ and BnOmH+ clusters (n e 3, m e 4) with D2O have been studied over a collision energy
range from 0.1 to 10 eV (center of mass). The reactivity and product branching are found to be highly dependent
on the structure of the reactant ion. When available, the preferred site of attack is on a terminal B atom, and
the chemistry is dominated by O and OD addition. Even for the most reactive clusters the peak reaction
efficiency is only 5-7%, indicating the presence of a bottleneck to reaction. When the reactant has no terminal
B atoms, reaction is 1 order of magnitude less efficient and appears to be dominated by attack at nonterminal
B atoms. The BnOmH+ react similarly, suggesting that the added H atom does not block the reactive sites.
This is in contrast to the isoelectronic reaction with HF, where H addition decreased reactivity dramatically.
The results are compared with those for related reactions, and with recent ab initio results. In general, theory
is consistent with experiment; however, there remain a few problem species.
BnOmHx chemistry is critical in combustion of boron, a
potential high energy density fuel additive. Boron particles are
coated with a BnOmHx layer, and the chemistry and properties
of this "oxide" layer control particle ignition. In addition,