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High‐pressure Raman study of dense methane: CH 4 and CD 4
Author(s) -
Wu Y. H.,
Sasaki S.,
Shimizu H.
Publication year - 1995
Publication title -
journal of raman spectroscopy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.748
H-Index - 110
eISSN - 1097-4555
pISSN - 0377-0486
DOI - 10.1002/jrs.1250261007
Subject(s) - raman spectroscopy , diamond anvil cell , solid solution , chemistry , phase (matter) , phase transition , analytical chemistry (journal) , methane , molecule , crystallography , spectral line , high pressure , thermodynamics , optics , organic chemistry , astronomy , physics
High‐pressure Raman spectra of liquid and solid CH 4 and CD 4 were measured up to 18 and 13 GPa, respectively, at 300 K in a gasketed diamond‐anvil cell. On the basis of visual observations under the polarizing microscope and changes in the Raman spectra, it was confirmed that there are only two solid phases (I and VII) for CH 4 and CD 4 at 300 K up to 18 GPa; no solid‐solid phase transition was found around 12 GPa, in contrast to earlier claims. In phase VII, some molecules are orientationally ordered, whereas others are orientationally disordered, just like the low‐temperature solid phases II, III, IV and V.