We present a kinetic study of the reaction Rb + N20 ---, Rb + N20 kNro by direct spectroscopic monitoring of ground state atomic rubidium in the time domain. Rb(52Sm/2) was generated by the pulsed irradiation of rubidium halide vapors at elevated temperatures in the presence of low concentrations of N20 and excess helium buffer gas. Digitized decay profiles of the atom during reaction were recorded photoelectrically in the "single-shot mode" by time-resolved atomic resonance absorption spectroscopic measurements of the optically resolved Rydberg transitions at h = 420.2 nm (Rb(6,o(2P3/2)) --Rb(5s(2Si/2))) which were analyzed by computer.
Absolute second-order rate constants (ks2o) were characterized for a necessarily limited temperature range of T = 709-888 K and were expressed in Arrhenius form: kN2o = 8.5+1.0 x 10 -tl exp(-5.4i-0.7 kJ mol-I/RT) cm 3 molecule -I s -1.
These data are compared with the analogous results reported previously for Li, Na, and K + N20 where use of such rate data as kinetic standards for the alkali atoms are discussed in some detail. The present result is found to be close in magnitude to that described hitherto for K + N20 and is considered briefly in terms of the potential surfaces involved in the reaction.