Molecular reorientational motion in liquid acetonitrile: Raman band shapes, diffusion constants and activation energy of reorientation
- 15 July 1973
- journal article
- research article
- Published by AIP Publishing in The Journal of Chemical Physics
- Vol. 59 (2), 751-758
- https://doi.org/10.1063/1.1680084
Abstract
Isotropic I α(ω) and anisotropic I β(ω) Raman band shape analyses of the ν1(a1) fundamentals in liquid CH3CN and CD3CN are reported. The ν2 and ν4 fundamentals are complicated by secondary structure and therefore were not studied in detail. Values of the perpendicular rotational diffusion constants , derived from the ν1(a1) fundamentals of both isotopic species are in good agreement with those obtained using NMR relaxation and dielectric methods and in addition agree closely with values calculated from microviscosity theory. The latter is based upon a model which involves a connection between the rotational and translational motions in liquids. In this model, reorientations perpendicular to the C3 axis proceed by small step Brownian diffusion and (Raman) for CD3CN yields an activation energy for liquid state molecular reorientations perpendicular to the C3 symmetry axis of , in good agreement with existing NMR and microviscosity values. Comparison of Raman data and results reported here with available infrared results reveals that the values are too high by a factor of 2. The source of the infrared errors is discussed.
Keywords
This publication has 16 references indexed in Scilit:
- Molecular reorientations in liquid benzene: raman line shapes and 2D NMR relaxationChemical Physics Letters, 1972
- Reorientation and Vibrational Relaxation as Line Broadening Factors in Vibrational SpectroscopyThe Journal of Chemical Physics, 1972
- Matrix isolation studies of methyl cyanide and methyl isocyanide in solid argonSpectrochimica Acta Part A: Molecular Spectroscopy, 1972
- Raman Scattering: Orientational Motions in LiquidsThe Journal of Chemical Physics, 1972
- An Infrared Spectroscopic Study of Rotational Diffusion and Intermolecular Interactions In AcetonitrileSpectroscopy Letters, 1972
- Carbon-13 Spin—Rotational Relaxation in CH3I and CH3CNThe Journal of Chemical Physics, 1971
- Raman Study of Liquids. I. Theory of the Raman Spectra of Diatomic Molecules in Inert SolutionsPhysical Review A, 1971
- Simple Photoelectric Laser Raman SpectrophotometerApplied Spectroscopy, 1968
- Molecular Motion in Infrared and Raman SpectraThe Journal of Chemical Physics, 1965
- INTENSITY IN THE RAMAN EFFECT: IV. RAMAN INTENSITY SUM RULES AND FREQUENCY ASSIGNMENTS FOR CH3CN, CD3CN, CH3CCl3, AND CD3CCl3Canadian Journal of Chemistry, 1955