| Popis: |
The strong nozzle-temperature dependence of the cluster content in supersonic beams enabled us to measure the chemiluminescent excitation functions of Ba(1S) atoms with NO2(2A2) molecules and with (NO2)n (mainly n = 2) clusters. The monomers react with appreciable cross section even at the lowest collision energy, and their excitation function is bimodal, exhibiting the type of minimum observed previously in other systems. The cross section for clusters, in contrast, rises monotonically from a threshold near zero collision energy. In a separate beam-gas experiment we have measured the temperature dependence of the rate constants for Ba-beam attenuation kT and for CL production kCL. Arrhenius plots for both quantities are non-linear and have opposite curvature. |
