title: Dynamic nuclear polarization of high-density atomic hydrogen in solid mixtures of molecular hydrogen isotopes.
abstract: We report on magnetic resonance studies of high-density atomic hydrogen and deuterium in solid hydrogen matrices at temperatures below 1 K. Average concentrations of H atoms ≈3×10(19)  cm(-3) are obtained in chemical tunneling reactions of isotope exchange with D atoms. The products of these reactions are closely located pairs of H atoms near D2 molecules with strong exchange interactions. We discovered a dynamic nuclear polarization effect on H atoms created by pumping the center of the H electron spin resonance spectrum, similar to the Overhauser effect in metals. Our results indicate that H atoms may be arranged inside molecular matrices at separations equivalent to local concentrations of 2.6×10(21)  cm(-3). This opens up a way to build a metallic state of atomic hydrogen at zero pressure.
authors.affiliation: Department of Physics and Astronomy, Wihuri Physical Laboratory, University of Turku, 20014 Turku, Finland.
authors.forename: S
authors.initials: S
authors.lastname: Sheludiakov
authors.affiliation: Department of Physics and Astronomy, Wihuri Physical Laboratory, University of Turku, 20014 Turku, Finland.
authors.forename: J
authors.initials: J
authors.lastname: Ahokas
authors.affiliation: Department of Physics and Astronomy, Wihuri Physical Laboratory, University of Turku, 20014 Turku, Finland.
authors.forename: J
authors.initials: J
authors.lastname: Järvinen
authors.affiliation: Department of Physics and Astronomy, Wihuri Physical Laboratory, University of Turku, 20014 Turku, Finland and Institute of Physics, Kazan Federal University, 18 Kremlyovskaya Street, Kazan 42008, Republic of Tatarstan, Russian Federation.
authors.forename: D
authors.initials: D
authors.lastname: Zvezdov
authors.affiliation: Department of Physics and Astronomy, Wihuri Physical Laboratory, University of Turku, 20014 Turku, Finland.
authors.forename: O
authors.initials: O
authors.lastname: Vainio
authors.affiliation: Department of Physics and Astronomy, Wihuri Physical Laboratory, University of Turku, 20014 Turku, Finland.
authors.forename: L
authors.initials: L
authors.lastname: Lehtonen
authors.affiliation: Department of Physics and Astronomy, Wihuri Physical Laboratory, University of Turku, 20014 Turku, Finland.
authors.forename: S
authors.initials: S
authors.lastname: Vasiliev
authors.affiliation: Department of Physics and Astronomy, Institute for Quantum Science and Engineering, Texas A&M University, College Station, Texas 77843, USA.
authors.forename: S
authors.initials: S
authors.lastname: Mao
authors.affiliation: Department of Physics and Astronomy, Institute for Quantum Science and Engineering, Texas A&M University, College Station, Texas 77843, USA.
authors.forename: V V
authors.initials: VV
authors.lastname: Khmelenko
authors.affiliation: Department of Physics and Astronomy, Institute for Quantum Science and Engineering, Texas A&M University, College Station, Texas 77843, USA.
authors.forename: D M
authors.initials: DM
authors.lastname: Lee