Abstract

(a). We have computed an approximate absorption spectrum for unstable intermediates H3≠ which constitute the transition states in the fundamental exchange reaction H+H2→H3≠→H2+H. Reaction takes place across the Siegbahn, Liu, Truhlar, Horowitz (SLTH) ground state energy surface, and electronic excitation is to the bound state that correlates with H*(22P)+H2. Features in the spectrum are indicative of the favored turning points for the mean of many classical trajectories across the SLTH surface. (b). Preliminary experimental data are reported which give evidence of emission arising from the transition states of NaI≠* in the (cw or pulsed) photolysis of NaI→222nmNaI≠*→Na*(32P)+I. The observed transition state emission is compared with a simple calculation.