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Raman matrix isolation spectroscopy of dihydrogen. II. Aggregation processes in argon

Journal Article · · Journal of Chemical Physics; (USA)
DOI:https://doi.org/10.1063/1.458468· OSTI ID:6982177
; ;  [1]
  1. Laboratoire de Spectrochimie Moleculaire (CNRS, UA 508) Universite Pierre et Marie Curie, 4 Place Jussieu 75252 Paris Cedex 05, France (FR)

The vibrational spectra of H{sub 2}, D{sub 2}, and HD trapped in solid argon were examined as a function of concentration and sample annealing. Before annealing, increasing the hydrogen concentration only leads to an asymmetrical broadening and a small blue shift of the {ital Q}( {ital J}) lines assigned to monomeric species. These observations are believed due to formation of low stoichiometry aggregates. After annealing above 35 K, new features---10 cm{sup {minus}1} blue shifted with respect to monomer and small aggregate lines---appear with properties comparable to those reported for solid dihydrogen at 2 K. Force field calculations on aggregates involving two to six molecules (including ortho/para and isotopic mixtures) allow a semiquantitative interpretation of the experimental data, and suggest an aggregation degree larger than six. Finally it is concluded that a possible interpretation of all the data is the formation of microcrystals upon annealing, tied to the low solubility and the high mobility of dihydrogen in solid argon.

OSTI ID:
6982177
Journal Information:
Journal of Chemical Physics; (USA), Journal Name: Journal of Chemical Physics; (USA) Vol. 92:1; ISSN JCPSA; ISSN 0021-9606
Country of Publication:
United States
Language:
English