Glow-Discharge Shock Tube for Studying Chemiluminescent, Surface-Catalytic, and Gas-Phase Reaction Rates; Temperature Dependence of NO–O and CO–O Chemiluminescence

Abstract

The ordinary glow-discharge tube has been used extensively to study both surface and gas-phase recombination rates, as well as chemiluminescent reactions, typically at room temperature. The combination of a glow-discharge flow tube with a shock-tube driver to provide a considerable extension of atom fluxes, temperatures, and densities for the study of these kinetic processes is described. In operation, the ordinary glow-discharge-tube situation appropriate to the particular process under study is first established and, then, a shock is propagated into the predissociated gas by a driver upstream of the rf region. Typically, the shock strength is less than that which causes further dissociation. Under these conditions, the effect of the shock is to compress, heat, and accelerate to high speed those species already in the glow tube. The high temperature and compression provide a means for studying the temperature dependence of gas-phase recombination processes and chemiluminescent reactions, while the high-speed flow, in increasing the atom flux, provides a means for studying surface-catalysis phenomena occurring on a short time scale (<1 msec). Application of the present technique to determine the temperature dependences of the NO–O and CO–O chemiluminescent reactions is described in considerable detail.