Reaction dynamics of Na*(4 (2)P)+H2: Effect of reactant orbital alignment on reactivity and product rotational state distribution.

Abstract

We have investigated the direct reaction of ${\mathrm{Na}}^{\mathrm{*}}$(4 $^{2}$P) with ${\mathrm{H}}_{2}$ to form the product NaH. Using far-wing absorption techniques, we have measured absorption into the ${\mathrm{NaH}}_{2}$ collision complex, followed by branching into nonreactive (formation of ${\mathrm{Na}}^{\mathrm{*}}$) or reactive (formation of NaH[X $^{1}\mathrm{\ensuremath{\Sigma}}^{+}$(v'',J'')]) channels. We have observed the reaction to occur both via the attractive potential-energy surfaces and over a barrier on the repulsive surfaces. We have studied the effect of reactant orbital alignment on product rotational distribution for v''=1. Specifically we find reaction on the repulsive surfaces leads preferentially to low rotational product states of NaH, while reaction on the attractive surfaces leads preferentially to high rotational states.