title: Surface Temperature Dependence of Hydrogen Ortho-Para Conversion on Amorphous Solid Water.
abstract: The surface temperature dependence of the ortho-to-para conversion of H_{2} on amorphous solid water is first reported. A combination of photostimulated desorption and resonance-enhanced multiphoton ionization techniques allowed us to sensitively probe the conversion on the surface of amorphous solid water at temperatures of 9.2-16 K. Within a narrow temperature window of 8 K, the conversion time steeply varied from ∼4.1×10^{3} to ∼6.4×10^{2}  s. The observed temperature dependence is discussed in the context of previously suggested models and the energy dissipation process. The two-phonon process most likely dominates the conversion rate at low temperatures.
authors.affiliation: Institute of Low Temperature Science (ILTS), Hokkaido University, Sapporo 060-0819, Japan.
authors.forename: Hirokazu
authors.initials: H
authors.lastname: Ueta
authors.affiliation: Institute of Low Temperature Science (ILTS), Hokkaido University, Sapporo 060-0819, Japan.
authors.forename: Naoki
authors.initials: N
authors.lastname: Watanabe
authors.affiliation: Institute of Low Temperature Science (ILTS), Hokkaido University, Sapporo 060-0819, Japan.
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Hama
authors.affiliation: Institute of Low Temperature Science (ILTS), Hokkaido University, Sapporo 060-0819, Japan.
authors.forename: Akira
authors.initials: A
authors.lastname: Kouchi