Ortho-positronium reactions in water studied by positron annihilation age-momentum correlation

Tetsuya Hirade, Toshitaka Oka, Lee Jeong Jae

Research output: Chapter in Book/Report/Conference proceedingConference contribution

3 Citations (Scopus)


Temperature dependence on S(t), positron age dependent shape parameter of annihilation gamma-rays, in water was observed. S(t) at the ortho-Ps pick off annihilation time region were higher at higher temperatures. It is indicating that there are more reactions of ortho-Ps at higher temperature. Hence it was successfully indicated that the longest lifetime, i.e. ortho-Ps component, on positron annihilation lifetime spectra for water could be shorter at higher temperatures. The radical reactions, such as PsOH formation or ortho-Ps oxidation by hydroxyl radicals, are spin dependent reactions. The geminate pair of ortho-Ps and hydroxyl radical in water can give spin dependent reaction and the enhancement of S(t) with certain time interval, i.e. quantum beats, were expected. It was observed even for water at 11°C. It is probably indicating the hyperfine coupling constants of hydroxyl radicals in water.

Original languageEnglish
Title of host publicationProgress in Positron Annihilation
PublisherTrans Tech Publications Ltd
Number of pages6
ISBN (Print)9780878492084
Publication statusPublished - 2011

Publication series

NameMaterials Science Forum
ISSN (Print)0255-5476
ISSN (Electronic)1662-9752


  • Geminate pairs
  • Hydrated electrons
  • OH radical
  • Positron
  • Positronium
  • Radical reaction
  • Spin conversion
  • Spur
  • Water

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering


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