Collisional dissociation and chemical relaxation of alkali halide molecules: 2000ndash;4200 K

摘要

Shockhyphen;induced dissociation and the subsequent chemical relaxation processes of diatomic alkali halide molecules have been studied by timehyphen;resolved absorption spectrometry of alkali atoms, halide ions, and alkali halide molecules. The salts studied in detail are NaCl, KBr, RbCl, RbBr, CsCl, CsBr, and CsI. Rate coefficients have been determined in the temperature range2000ndash;4200 K for these processes: collisional detachment by argon Ar+Xminus;rarr;Ar+X+e; ionization of alkali atoms by thermal electron impacte+M0rarr;2e+M+; ionndash;ion neutralization M++Xminus;rarr;M0+X0; collisional dissociation to ions Ar+MXrarr;Ar+M++Xminus;; and finally, collisional dissociation to atoms Ar+MXrarr;Ar+M0+X0. The branching ratio (probability of dissociation to atoms)/(probability of dissociation to ions) is, in all cases studied, favorable to formation of ion pairs, relative to the equilibrium distribution of atom pairs/ion pairs. However, in every case except CsI, the primary collisional dissociation process gives a significant fraction of atom pairs.