Electron spin resonance study of atomic hydrogen stabilized in solid neon below 1 K
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2018 American Physical Society. We report on an electron spin resonance study of atomic hydrogen stabilized in solid Ne matrices carried out at a high field of 4.6T and temperatures below 1K. The films of Ne, slowly deposited on the substrate at a temperature of 1K, exhibited a high degree of porosity. We found that H atoms may be trapped in two different substitutional positions in the Ne lattice as well as inside clusters of pure molecular H2 in the pores of the Ne film. The latter type of atoms was very unstable against recombination at temperatures 0.3-0.6K. Based on the observed nearly instant decays after rapid small increases of temperature, we evaluate the lower limit of the recombination rate constant kr510-20cm3s-1 at 0.6K, five orders of magnitude larger than that previously found in the thin films of pure H2 at the same temperature. Such behavior assumes a very high mobility of atoms and may indicate a solid-to-liquid transition for H2 clusters of certain sizes, similar to that observed in experiments with H2 clusters inside helium droplets [Phys. Rev. Lett. 101, 205301 (2008)PRLTAO0031-900710.1103/PhysRevLett.101.205301]. We found that the efficiency of dissociation of H2 in neon films is enhanced by two orders of magnitude compared to that in pure H2 as a result of the strong action of secondary electrons.