INFRARED ABSORPTION OF THE $nu$$sub 3$ FUNDAMENTAL OF LIQUID AND SOLID CH$sub 4$ AND CD$sub 4$
The nu /sub 3/ fundamental of CH/sub 4/, CD/sub 4/, and solutions of CD/ sub 4/ in CH/sub 4/ was studied in the liquid and solid state from 105 to 28 deg K. The broad liquid-state absorption approximates the gas-phase vibration- rotation envelope in the wings, but has significantly more absorption at the band center. This deviation is consistent with the assumption that molecules in the liquid can undergo hindered rotation. Cme consequence of this model is that rotatory motion of molecules is in part librational in character and selection rules predict an intense Q branch and weaker P, R, S, and O branches. Another consequence is that the liquid environment may induce molecular dipoles causing Raman selection rules to be operative that contribute further to an intensification of the Q branch. The bandwidth decreases gradually with temperature but undergoes no discernible discontinuous change on passing through the freezing point, which suggests that rotatory motion persists in the solid phase. The bandwidth of the fundamental of liquid and solid CD/sub 4/ is narrower than CH/sub 4/ but behaves in a similar fashion with temperature. The band shape and position of nu /sub 3/ of CD/sub 4/ in solution with CH/sub 4/ is indistinguishable from that of pure liquid CD/sub 4/, and suggests that resonance broadening or coupling of rotatory motion is not important for this phase. In the solid state, however, the alpha /sub 3/ bandwidth of CD/sub 4/ in the CD/sub 4/--CH/sub 4/ solut ion is slightly larger than the nu /sub 3/ bandwidth of pure CD/sub 4/. (auth)
- Research Organization:
- California Inst. of Tech., Pasadena
- Sponsoring Organization:
- USDOE
- NSA Number:
- NSA-18-008401
- OSTI ID:
- 4130615
- Journal Information:
- Journal of Chemical Physics (U.S.), Journal Name: Journal of Chemical Physics (U.S.) Vol. Vol: 40; ISSN JCPSA
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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