Vibrational and rotational relaxation of CDCl3 in nonpolar solvents

Abstract

Articles you may be interested inA study of molecular vibrational relaxation mechanism in condensed phase based upon mixed quantumclassical molecular dynamics. I. A test of IBC model for the relaxation of a nonpolar solute in nonpolar solvent at high density Solvent dependence of the deuteron quadrupole coupling constant of CDCl3 determined by 2H spinlattice relaxation and Raman line shape studies Vibrational and reorientational correlation functions and correlation times for the VI band of CDCl 3 in the pure liquid and in solutions in carbon tetrachloride. n -hexane. and carbon disulfide have been obtained using spontaneous Raman scattering. and reorientational correlation times have been obtained from deuterium spin relaxation measurements. The concentration dependence of the reorientational correlation times in the CDCl 3 /CS 2 and CDCl/ n -hexane solutions closely paralleled the solution viscosity. while in CDCl/CCI 4 mixtures. the correlation time exhibited little concentration dependence. These features reflect differences in the anisotropy of the intermolecular potential experienced by the CDCl 3 molecules in these solutions. The reorientational correlation functions for the pure liquid exhibited time dependences different from that of the extended rotational diffusion models and a stochastic second-order memory function model. The temperature dependence of the vibrational relaxation times and vibrational second moments of VI in CDCl 3 liquid is not consistent with Kubo-type dephasing models. The vibrational relaxation data indicate that collisional dephasing (Fischer-Lauberau model) is the probable mechanism of relaxation. but do not rule out contributions from energy relaxation via independent binary collisions. In CDCl 3 1CS 2 mixtures. the band frequency and the bandwidth exhibit concentration dependence in accord with microscopic concentration fluctuations in the solution.4280

Interpretation of Vapor-Liquid Frequency Shift of CH stretching vibration of chloroform and Fluoroform

“…It is important to note that, based on the experi mental studies on the temperature [27,28] and pres sure [29] dependences of infrared and Raman band peaks, the CH stretching frequency in liquid chloro form increases both with increasing pressure and tem perature. This is possible only when the equilibrium H ■ ■ • CI intermolecular distances are in the vicinity of "s" belonging to the minimum of zlv(s) function.…”

“…The calculated vibrational frequency shifts are reported in Table 3. It was found by Raman spec troscopic measurement that the frequency of the CD stretching vibration shifts to the blue with increasing temperature by about 0.020 cm "l/°C around room temperature [27], This is in good agreement with the value of 0.024 cm "7°C for the CH vibrational fre quency estimated from the temperature dependence of infrared band peaks [28]. Although the temperature dependence calculated from Table 3 (0.002 cm-1/°Q is small by comparison with experiment, the direction of the shift agrees with the experimentally observed one.…”

“…Since there are experimental data available in the literature on the pressure [29] and temperature [27,28] dependence of the CH stretching frequency of chloro form. a comparison with calculated values can be ex pected to be a sensitive test of the validity of the approximations employed in our model calculations.…”

Raman study of vibrational relaxation of 1-alcynes in solutionv(≡CH) andv(C≡C) modes of 1-hexyne and 1-decyne

“…Up to recently the only expression proposed for qbv(t ) was Kubo and Rothschild's relation [32] *v(t) = exp [ -M2rM~(exp ( --t/%,) --1 + t/%~)], (9) where M 2 is the vibrational second moment and r M the correlation time for the frequency fluctuations Am. This formula is obtained by adopting <AoJ(t)Aa~(0)) = M2ex p ( -t/r~a).…”

“…rather heavy molecules, should be preferred. A few studies in this line have already been realized by spontaneous Raman spectroscopy [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18]. They nearly always bear on pure liquids.…”