Trapping sites of hydrogen atoms in solid HD and D_2: An electron spin echo study

摘要

Trapping sites of H and D atoms in solid HD and D_2 have been determined using electron spin echo (ESE) spectroscopy. It was found that all the H and Dd atoms are trapped in substitutional sites and that the H atoms push back surrounding HD(D_2) molecules to produce local lattice distortion around the atoms, whereas the D atoms do not. It is expected that the local lattice distortion is produced by zero-point motion of the H atoms whose amplitude is larger than that of host HD(D_2) molecules and that the isotope effect is due to difference in the amplitude between the H and D atoms. The lattice distortion around the H atoms may induce the increase in rate constant for the tunneling reaction D + DH -> D_2 + H with the increase in temperature in solid HD reported in Chem. Phys. Lett. 261, 463 (1996).