title: ESR study of atomic hydrogen and tritium in solid T2and T2:H2matrices below 1 K.
abstract: We report on the first ESR study of atomic hydrogen and tritium stabilized in solid T2and T2:H2matrices down to 70 mK. The concentrations of T atoms in pure T2approached 2 × 1020cm-3(0.60%) and record-high concentrations of H atoms ∼1 × 1020cm-3(0.33%) were reached in T2:H2solid mixtures where a fraction of T atoms became converted into H due to the isotopic exchange reaction T + H2→ TH + H. The maximum concentrations of unpaired T and H atoms were limited by their recombination which becomes enhanced by efficient atomic diffusion due to the presence of a large number of vacancies and phonons generated in the matrices by β-particles. Recombination also appeared in an explosive manner, both being stimulated and spontaneously in thick films where sample cooling was insufficient. We suggest that the main mechanism for H and T migration is physical diffusion related to tunneling or hopping to vacant sites in contrast to tunneling chemical exchange reactions which govern diffusion of H and D atoms created in H2and D2matrices by other methods.
authors.affiliation: Wihuri Physical Laboratory, Department of Physics and Astronomy, University of Turku, 20014 Turku, Finland. seshel@utu.fi.
authors.forename: S
authors.identifier: http://orcid.org/0000-0001-9909-2360
authors.initials: S
authors.lastname: Sheludiakov
authors.affiliation: Wihuri Physical Laboratory, Department of Physics and Astronomy, University of Turku, 20014 Turku, Finland. seshel@utu.fi.
authors.forename: J
authors.identifier: http://orcid.org/0000-0001-5857-1541
authors.initials: J
authors.lastname: Ahokas
authors.affiliation: Wihuri Physical Laboratory, Department of Physics and Astronomy, University of Turku, 20014 Turku, Finland. seshel@utu.fi.
authors.forename: J
authors.initials: J
authors.lastname: Järvinen
authors.affiliation: Wihuri Physical Laboratory, Department of Physics and Astronomy, University of Turku, 20014 Turku, Finland. seshel@utu.fi.
authors.forename: L
authors.initials: L
authors.lastname: Lehtonen
authors.affiliation: Wihuri Physical Laboratory, Department of Physics and Astronomy, University of Turku, 20014 Turku, Finland. seshel@utu.fi.
authors.forename: O
authors.identifier: http://orcid.org/0000-0001-6045-2963
authors.initials: O
authors.lastname: Vainio
authors.affiliation: Wihuri Physical Laboratory, Department of Physics and Astronomy, University of Turku, 20014 Turku, Finland. seshel@utu.fi.
authors.forename: S
authors.initials: S
authors.lastname: Vasiliev
authors.affiliation: Institute for Quantum Science and Engineering, Department of Physics and Astronomy, Texas A&M University, College Station, TX 77843, USA.
authors.forename: D M
authors.initials: DM
authors.lastname: Lee
authors.affiliation: Institute for Quantum Science and Engineering, Department of Physics and Astronomy, Texas A&M University, College Station, TX 77843, USA.
authors.forename: V V
authors.identifier: http://orcid.org/0000-0002-3362-3891
authors.initials: VV
authors.lastname: Khmelenko