Nuclear spin dependence of the reaction of H(3)+ with H2. II. Experimental measurements

Kyle N Crabtree; Carrie A Kauffman; Brian A Tom; Eftalda Beçka; Brett A McGuire; Benjamin J McCall

doi:10.1063/1.3587246

Nuclear spin dependence of the reaction of H(3)+ with H2. II. Experimental measurements

J Chem Phys. 2011 May 21;134(19):194311. doi: 10.1063/1.3587246.

Authors

Kyle N Crabtree¹, Carrie A Kauffman, Brian A Tom, Eftalda Beçka, Brett A McGuire, Benjamin J McCall

Affiliation

¹ Department of Chemistry, University of Illinois, Urbana, Illinois 61801, USA.

PMID: 21599063
DOI: 10.1063/1.3587246

Abstract

The nuclear spin dependence of the chemical reaction H(3)(+)+ H(2) → H(2) + H(3)(+) has been studied in a hollow cathode plasma cell. Multipass infrared direct absorption spectroscopy has been employed to monitor the populations of several low-energy rotational levels of ortho- and para-H(3)(+) (o-H(3)(+) and p-H(3)(+)) in hydrogenic plasmas of varying para-H(2) (p-H(2)) enrichment. The ratio of the rates of the proton hop (k(H)) and hydrogen exchange (k(E)) reactions α ≡ k(H)/k(E) is inferred from the observed p-H(3)(+) fraction as a function of p-H(2) fraction using steady-state chemical models. Measurements have been performed both in uncooled (T(kin) ∼ 350 K) and in liquid-nitrogen-cooled (T(kin) ∼ 135 K) plasmas, marking the first time this reaction has been studied at low temperature. The value of α has been found to decrease from 1.6 ± 0.1 at 350 K to 0.5 ± 0.1 at 135 K.