Low Temperature Physics: 29, 505 (2003); https://doi.org/10.1063/1.1542539 (5 pages)
Физика Низких Температур: Том 29, Выпуск 6 (Июнь 2003), c. 678-683 ( к оглавлению , назад )
ESR investigation of hydrogen and deuterium atoms in impurity-helium solids
S.I. Kiselev, V.V. Khmelenko, E.P. Bernard, and D.M. Lee
Laboratory of Atomic and Solid State Physics Cornell University, Ithaca, NY 14853-2501, USA
Received December 19, 2002
Impurity-helium solids (Im-He solids) are porous solids created by injecting a beam of mixed helium and impurity gases into superfluid 4He. In this work we use electron spin resonance (ESR) techniques to investigate Im-He solids containing atoms and molecules of hydrogen and/or deuterium. We have performed studies of low temperature (T ~ 1.35 K) tunnelling chemical reactions in which deuterium atoms replace the hydrogen atoms bound in H2 or HD molecules to produce large (up to 7.5×1017cm-3) and relatively stable concentrations of free hydrogen atoms. The time dependence of H and D atom concentrations has been investigated for Im-He samples with different initial ratios of hydrogen and deuterium ranging from 1:20 to 1:1.The satellite ESR lines associated with the dipolar coupling of electron spins of H and D atoms to the nuclear moments of the hydrogen nuclei found in neighboring molecules have been observed in Im-He solids. The forbidden hyperfine transition of atomic hydrogen involving the mutual spin flips of electrons and protons has also been observed.