Measurements of energy partitioning in H2 formation by photolysis of amorphous water ice

Akihiro Yabushita, Tetsuya Hama, Daisuke Iida, Noboru Kawanaka, Masahiro Kawasaki, Naoki Watanabe, Michael N.R. Ashfold, Hans Peter Loock

Research output: Contribution to journalArticlepeer-review

24 Citations (Scopus)


We demonstrate experimentally that photodissociation of amorphous solid water at 100 K results in formation of H2 molecules with an ortho/para ratio of gOPR = 3. Two distinct mechanisms can be identified: endothermic abstraction of a hydrogen atom from H2O by a photolytically produced H atom yields vibrationally cold H2 products, whereas exothermic recombination of two H-atom photoproducts yields translationally and internally hot H2. These results are in accord with predictions by molecular dynamics calculations and their astrophysical implications are discussed.

Original languageEnglish
Pages (from-to)L69-L72
JournalAstrophysical Journal
Issue number1 PART 2
Publication statusPublished - 2008
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

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