Raman Studies on Solid CO2 and N2 with Excess He at Pressures up to 40 GPa

A. P. Jephcoat, H. Olijnyk

    Research output: Contribution to journalArticlepeer-review

    Abstract

    Raman spectra of CO2 and the van-der-Waals compound He(N2)11 were obtained under nearly hydrostatic pressures up to 40 GPa. The pressure induced changes of the librational spectra suggest that solid CO2 does not transform directly from phase-I (cubic Pa3) to phase-Ill (orthorhombic Cmca). An intermediate phase-IV. which may involve only minor modifications of phase-I, is formed prior to the transition to Cmca structure Phases IV and III coexist over some pressure range. The pressure shifts of all four Raman active librons of phase-Ill were determined over a wide pressure range and are compared to previous theoretical results. Spectra of external and internal modes of the van-der-Waals compound He(N2)11 are very similar to those of ε-N2 and imply a close relationship between the structures of He(N2)11 and ε-N2. The observed splitting of the main vibron of isotopic species 14N-15N indicates that in addition to factor-group interactions site effects are responsible for the observed splittings of the 14N2 main vibron of He(N2)11.

    Original languageEnglish
    Pages (from-to)121-123
    Number of pages3
    JournalReview of High Pressure Science and Technology/Koatsuryoku No Kagaku To Gijutsu
    Volume8
    Issue number2
    DOIs
    Publication statusPublished - 1998

    Keywords

    • high pressure
    • molecular crystals
    • phase transitions
    • vibrational spectroscopy

    ASJC Scopus subject areas

    • Chemistry(all)
    • Materials Science(all)
    • Condensed Matter Physics

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