Diffusion of hydrogen fluoride in solid parahydrogen

Hiroki Ooe, Yuki Miyamoto, Susumu Kuma, Kentarou Kawaguchi, Kyo Nakajima, Itsuo Nakano, Noboru Sasao, Jian Tang, Takashi Taniguchi, Motohiko Yoshimura

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

We studied diffusion of hydrogen fluoride (HF) in solid parahydrogen (pH2) around 4 K. Diffusion rates were determined from time dependence of FT-IR spectra of HF monomers. The absorption of HF monomers shows temporal decay due to dimerization reaction via diffusion. It was found that the rates are affected by the sample temperature, the initial HF concentration, and annealing of samples. The observed non-Arrhenius-type temperature dependence suggests that the diffusion is dominated by a quantum tunneling process, that is, "quantum diffusion." Deceleration of the diffusion in condensed samples and acceleration in annealed samples were also observed. These results can be attributed to the fact that lower periodicity of samples due to impurities or defects suppresses the quantum tunneling. It seems to be difficult to explain the observed dependences by three possible diffusion mechanisms, exchange of chemical bonds, direct cyclic exchange, and exchange with mobile vacancy. Therefore, we propose a hypothetical mechanism by exchange of vacancies originating from quantum effect.

Original languageEnglish
Article number214309
JournalJournal of Chemical Physics
Volume138
Issue number21
DOIs
Publication statusPublished - Jun 7 2013

ASJC Scopus subject areas

  • Physics and Astronomy(all)
  • Physical and Theoretical Chemistry

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