Experimental tests of reaction rate theory: Mu+H2 and Mu+D2

Bimolecular rate constants for the thermal chemical reactions of muonium (Mu) with hydrogen and deuterium: Mu+H2→MuH+H and Mu+D2→MuD+D: over the temperature range 473--843 K are reported. The Arrhenius parameters and 1σ uncertainties for the H2 reaction are log A (cm3 molecule-1 s-1) = -9.605 +- 0.074 and E/sub a/ = 13.29 +- 0.22 kcal mol-1, while for D2 the values are -9.67 +- 0.12 and 14.73 +- 0.40, respectively. These results are significantly more precise than those reported earlier by Garner et al. For the Mu reaction with H2 our results are in excellent agreement with the 3D quantum mechanical calculations of Schatz on the Liu--Siegbahn--Truhlar--Horowitz potential surface, but the data for both reactions compare less favorably with variational transition-state theory, particularly at the lower temperatures