Tunneling chemical reactions in solid parahydrogen: direct measurement of the rate constants of R + H2 --> RH + H (R = CD3,CD2H,CDH2,CH3) at 5 K

Hiromichi Hoshina; Mizuho Fushitani; Takamasa Momose; Tadamasa Shida

doi:10.1063/1.1642582

Tunneling chemical reactions in solid parahydrogen: direct measurement of the rate constants of R + H2 --> RH + H (R = CD3,CD2H,CDH2,CH3) at 5 K

J Chem Phys. 2004 Feb 22;120(8):3706-15. doi: 10.1063/1.1642582.

Authors

Hiromichi Hoshina¹, Mizuho Fushitani, Takamasa Momose, Tadamasa Shida

Affiliation

¹ Division of Chemistry, Graduate School of Science, Kyoto University, 606-8502, Japan.

PMID: 15268533
DOI: 10.1063/1.1642582

Abstract

Tunneling chemical reactions between deuterated methyl radicals and the hydrogen molecule in a parahydrogen crystal have been studied by Fourier transform infrared spectroscopy. The tunneling rates of the reactions R + H2 --> RH + H (R = CD3,CD2H,CDH2) in the vibrational ground state were determined directly from the temporal change in the intensity of the rovibrational absorption bands of the reactants and products in each reaction in solid parahydrogen observed at 5 K. The tunneling rate of each reaction was found to differ definitely depending upon the degree of deuteration in the methyl radicals. The tunneling rates were determined to be 3.3 x 10(-6) s(-1), 2.0 x 10(-6) s(-1), and 1.0 x 10(-6) s(-1) for the systems of CD3, CD2H, and CDH2, respectively. Conversely, the tunneling reaction between a CH3 radical and the hydrogen molecule did not proceed within a week's time. The upper limit of the tunneling rate of the reaction of the CH3 radical was estimated to be 8 x 10(-8) s(-1).