Spatial Diffusion of Hydrogen Atoms in Normal and Para-Hydrogen Molecular Films at Temperature 0.7 K

Abstract

<p>We report on electron spin resonance studies of H atoms stabilized in solid H2 flms at temperature 0.7 K and in a magnetic feld of 4.6 T. The H atoms were produced by bombarding H2 flms 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 flms 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 infuence of ortho-H2 molecules on spatial difusion of H atoms in solid H2 flms. The spatial difusion of H atoms in both normal and para-H2 flms is faster than the difusion obtained from the measurement of H atom recombination. The rate of spatial difusion of H atoms in para-H2 flms was slower in comparison with that in the normal H2 flms. We discuss possible explanations of these observations. <br></p>