Dynamics of the chemiluminescent oxidation of zinc atoms by nitrous oxide

Abstract

The dynamics of the chemiluminescent oxidation of zinc atoms by nitrous oxide to form ZnO* have been studied utilizing a laser vaporization pulsed beam source to produce the zinc reactant. The kinetic energy dependence of the chemiluminescent reaction cross section has a threshold at 1.6×10−19 J/molecule (1.0 eV) in the center of mass; this threshold value has been used to estimate the dissociation energy of ZnO as D≥4.48×10−19±0.32×10−19 J [2.8(±0.2) eV]. The reaction cross section increases with increasing kinetic energy in accord with the Arrhenius model from threshold to 3.2×10−19 J (2.0 eV), but then increases more rapidly. Above threshold, small amounts of thermal energy added to the N2O reactant increase the reaction cross section 70 times more than the equivalent energy supplied as relative kinetic energy. This energy selectivity is interpreted in terms of an electron jump reaction mechanism which is significantly enhanced by the ν2 bending vibrational mode of N2O.