Electron spin resonance study of atomic hydrogen stabilized in solid neon below 1 K



: Sheludiakov S, Ahokas J, Jarvinen J, Lehtonen L, Vasiliev S, Dmitriev YA, Lee DM, Khmelenko VV

Publisher: AMER PHYSICAL SOC

: 2018

: Physical Review B

: PHYSICAL REVIEW B

: PHYS REV B

: ARTN 104108

: 97

: 10

: 12

: 2469-9950

: 2469-9969

DOI: https://doi.org/10.1103/PhysRevB.97.104108

: https://research.utu.fi/converis/portal/detail/Publication/31575306


We report on an electron spin resonance study of atomic hydrogen stabilized in solid Ne matrices carried out at a high field of 4.6 T and temperatures below 1 K. The films of Ne, slowly deposited on the substrate at a temperature of similar to 1 K, 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 H-2 in the pores of the Ne film. The latter type of atoms was very unstable against recombination at temperatures 0.3-0.6 K. Based on the observed nearly instant decays after rapid small increases of temperature, we evaluate the lower limit of the recombination rate constant k(r) >= 5 x 10(-20) cm(3) s(-1) at 0.6 K, five orders of magnitude larger than that previously found in the thin films of pure H-2 at the same temperature. Such behavior assumes a very high mobility of atoms and may indicate a solid-to-liquid transition for H-2 clusters of certain sizes, similar to that observed in experiments with H-2 clusters inside helium droplets [Phys. Rev. Lett. 101, 205301 (2008)]. We found that the efficiency of dissociation of H-2 in neon films is enhanced by two orders of magnitude compared to that in pure H-2 as a result of the strong action of secondary electrons.

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