ISSN:
1089-7690
Source:
AIP Digital Archive
Topics:
Physics
,
Chemistry and Pharmacology
Notes:
Our paper presents a fit of an orientational equilibrium renewal process in terms of a sequence of random events of free rotational motion and libratory oscillations [Lindenberg and Cukier, J. Chem. Phys. 62, 3271 (1975)] to new pure-rotational spectra and correlation data of the ν3 mode (367 cm−1) of liquid chloroform–Cl-35 at 300 and 213 K. The model fits are good; they account fully for the frequently observed (but rarely well-simulated) partial regain of the memory of the orientational coherence at intermediate time domains. Further, the physical-statistical picture of the nature of the orientational motion turns out to be that of a librator in a potential-well of a strongly temperature-dependent depth; stages of free rotation are significant but one order of magnitude shorter than the oscillatory regimes, even at room temperature and at ambient pressure. This contrasts notions of rotational motion hitherto held for such systems. Second, we explored the rotational correlation data of the C–H stretching mode ν1, which exhibits much faster vibrational relaxation than mode ν3, to ascertain empirically effects of significant vibration-rotation coupling in ν1. We find that this effect is significant for the longer time domains only. Finally, we report low-frequency depolarized Raman spectra (5–200 cm−1) at 212, 243, 273, and 295 K. They yield a temperature dependence of the peak-frequencies of the reduced Raman intensity (density-of-vibrational-states) which can only be reconciled with a predominance of librational motion within the liquid cage.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.465561
