Properties of liquid CS₂from the allowed light scattering spectra

Abstract

Measurements of the anisotropic Rayleigh and the allowed Raman spectra of carbon disulphide over the normal liquid range are described. The Raman reorientation times agree well with N.M.R. values and are qualitatively well predicted by the Stokes-Einstein-Debye formula with slip boundary conditions, although significant departures are found. The Hubbard relationship is obeyed. A careful comparison of the Rayleigh and anisotropic Raman intensities indicates that the orientational correlation parameter (g2) decreases with increasing temperature. Using values of g~ obtained in this way the ratio of the Rayleigh and Raman reorientation times is shown to be consistent with a small value for the correlation in angular velocity between molecules. The vibrational dephasing time is found to be roughly constant with temperature in contrast with the predictions of the theories for this quantity. An attempt is made to correlate its behaviour with that of the collision induced Raman spectra of CSv

Assessing the non-ideality of the CO2-CS2 system at molecular level: A Raman scattering study

“…The ν 1 symmetric stretch vibration, as an allowed Raman mode, gives rise to a strongly active polarised band. 20,32,82 In contrast to CI bands, this mode will mainly give access to mono-molecular information (discarding an extremely weak CI contribution acting in its far-wing), and for this reason, will not a priori constitute a so-sensitive probe of the intermolecular multibody interactions as the ν 2 and ν 3 modes. The 2ν 2 overtone, which is in principle expected to have a vanishing intensity, is in fact strongly active due to a Fermi resonance coupling with the ν 1 mode.…”

“…First, we will present the experimental observations using Raman spectroscopy on the ν 1 -2ν 2 CO 2 Fermi dyad domain, followed by those on the induced (ν 2 and ν 3 ) and allowed (ν 1 and 2ν 2 ) modes of CS 2 . Then, we will rationalize these observations using the collision induced framework of Madden et al for the forbidden CS 2 modes, 18,20,21,[23][24][25][26][27][28][29][30][31][32]35 and vibrational relaxation models to discuss the departures from ideality probed by the allowed CO 2 and CS 2 modes. Finally, we will discuss the non ideality of the mixture from the existence of two distinct solvation regimes with a transition characterised by a plateau domain found in the evolution of the spectroscopic observables with the concentration.…”

“…[4][5][6][7][8][9][10][11][12][13][14][15][16][17] In dense phase, the aim was to provide insight on the nature and time scale of the intermolecular interactions from "allowed" vibrational spectra or from the analysis of collision induced (CI) spectra which are unique probes of the multi-body interactions. [18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36] The study of the interaction of carbon dioxide with molecular liquids and complex fluids as ionic liquids is a field of current interest, motivated not only from the fundamental point of view but mainly under the impetuous motivation of understanding the interactions of CO 2 in the field of environmental studies. [67][68][69][70] Surprisingly, in this context, studies of the CO 2 -CS 2 binary mixture are extremely scarce.…”

Molecular dynamics simulation using hard particles

“…As a consequence, there is a scarcity of reliable data from which j, can be determined. The available information [74,75,76] suggests that j, is small compared to 1, and it is common practice among experimentalists to assume that j, = 0. Using kinetic theory, Evans and coworkers [17, 77,78] have derived explicit expressions for j, for hard ellipsoids and hard spherocylinders.…”

Evolution from quantum to classical fluctuation in low-frequency dynamics in liquids

“…The cooperative rotational dynamics of anisotropic molecules in liquids appears as a quasi-elastic light scattering spectrum called central mode or relaxational mode [1][2][3][4][5][6][7][8][9][10]. It shows a character of the classical fluctuation in the spectrum, that is, its Stokes to anti-Stokes intensity ratio I S (x)/I AS (x) at frequency shift x for carbon disulfide becomes unity in a frequency region less than several wavenumbers [11], while the usual relation I S ðxÞ=I AS ðxÞ ¼ e hx=k B T holds for structure-less low-frequency phonon modes (Boson peak) up to $100 cm À1 .…”