Spatial Diffusion of Hydrogen Atoms in Normal and Para-Hydrogen Molecular Films at Temperature 0.7 K
We report on electron spin resonance studies of H atoms stabilized in solid H2 films
at temperature 0.7 K and in a magnetic field of 4.6 T. The H atoms were produced by
bombarding H2 films with 100 eV electrons from a radiofrequency discharge run in
the sample cell. We observed a one order of magnitude faster H atom accumulation
in the films made of para-H2 gas with a small ortho-H2 concentration (0.2% ortho-H2 )
as compared with those made from normal H2 gas content (75% ortho-H2 ). We also
studied the influence of ortho-H2 molecules on spatial diffusion of H atoms in solid
H2 films. The spatial diffusion of H atoms in both normal and para-H2 films is faster
than the diffusion obtained from the measurement of H atom recombination. The rate
of spatial diffusion of H atoms in para-H2 films was slower in comparison with that in
the normal H2 films. We discuss possible explanations of these observations.
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