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Y. MIYAMOTO, Graduate School of Natural Science and Technology, Okayama University, 3-1-1 Tsushima-naka Okayama 700-8530, Japan; T. MOMOSE, Department of Chemistry, The University of British Columbia, 2036 Main Mall, Vancouver, British Columbia V6T 1Z1, Canada; H. KANAMORI, Department of Physics, Tokyo Institute of Technology, Ohokayama 2-12-1, Tokyo 152-8551, Japan.
FTIR absorption spectra of CH3F-( ortho -H2)n clusters in solid para -H2 were studied in the C-H stretching region (
3000 cm-1). As shown previously, the
3 C-F stretching band at 1040 cm-1 of the CH3F-( ortho -H2)n (n = 0
12) gives a distinct regular series of absorption lines in solid para -H2, which correspond to each n -th component of the cluster. On the other hand, broaden single lines were observed in the 3000 cm-1 region, which were assigned to the
1 and
4 modes with axial rotation. We found that their lineshape varied depending on ortho -H2 concentration in crystals and could be represented as superposition of the cluster components. Least square fitting based on the CH3F-( ortho -H2)n cluster model worked very well to resolve the broaden bands and provided us the linewidth and line shift of resolved lines. The large difference of the linewidth and line shift between the vibrational modes shows the distinct nature of each mode in cold quantum solids.