Liquids vibrational dephasing

Loring R F and Mukamel S 1985 Selectivity in coherent transient Raman measurements of vibrational dephasing in liquids J. Chem. Phys. 83 2116-28... 

The quasi-classical description of the Q-branch becomes valid as soon as its rotational structure is washed out. There is no doubt that at this point its contour is close to a static one, and, consequently, asymmetric to a large extent. It is also established [136] that after narrowing of the contour its shape in the liquid is Lorentzian even in the far wings where the intensity is four orders less than in the centre (see Fig. 3.3). In this case it is more convenient to compare observed contours with calculated ones by their characteristic parameters. These are the half width at half height Aa)i/2 and the shift of the spectrum maximum ftW—< > = 5a>+A, which is usually assumed to be a sum of the rotational shift 5larger scale A determined by vibrational dephasing. 

Fig. 3.8. The Q-branch Raman width alteration with condensation of nitrogen. The theoretical results for the strong (A) and weak (B) collision limits are shown together with experimental data for gaseous [89] ( ) and liquid nitrogen [145] ( ) (point a is taken from the CARS experiment of [136]). The broken curves in the inset are A and B limits whereas the intermediate solid curve presents the rotational contribution to line width at y = 0.3. The straight line estimates the contribution of vibrational dephasing [143], and the circles around it are the same liquid data but without rotational contribution.

Knaap E. W. Vibrational dephasing of diatomic molecules in liquids role of anharmonicity of the diatom, Chem. Phys. Lett. 58, 221-4 (1978). 

Kroon R., Baggen M., Lagendijk A. Vibrational dephasing in liquid nitrogen at high densities studied with time-resolved stimulated Raman gain spectroscopy, J. Chem. Phys. 91, 74-8 (1989). 

XVII. Subquadratic Quantum Number Dependence of the Overtone Vibrational Dephasing in Molecular Liquids... 

XVII. SUBQUADRATIC QUANTUM NUMBER DEPENDENCE OF THE OVERTONE VIBRATIONAL DEPHASING IN MOLECULAR LIQUIDS... 

This is a subject of great interest to the physical chemistry/chemical physics community. In this section we discuss how the mode coupling theory calculation of the friction on atoms connected by a chemical bond can lead to a better understanding of vibrational dephasing in dense liquids. In particular, the application of MCT is shown to provide a possible explanation of an old ill-understood problem. 

Vibrational Dephasing in Liquids Raman Echo and Raman Free-Induction Decay Studies... 

The first time-resolved investigations on vibrational dephasing and vibrational lifetimes of molecules in the liquid phase were reported in 1971 and 1972 by Kaiser et al. utilizing nonlinear Raman scattering (3,4). A combination of infrared excitation with spontaneous Raman probing... 

In this chapter we will first discuss coherent anti-Stokes Raman scattering (CARS) of simple liquids and binary mixtures for the determination of vibrational dephasing and correlation times. The time constants represent detailed information on the intermolecular interactions in the liquid phase. In the second section we consider strongly associated liquids and summarize the results of time-resolved IR spectroscopy (see, e.g., Ref. 17) on the dynamics of monomeric and associated alcohols as well as isotopic water mixtures. 

The concept of the Raman echo extends back to Hartmann in 1968 (27), and a few early experiments were performed on gas-phase electronic (28,29) and vibrational (30) transitions. However, it was the paper by Loring and Mukamel in 1985 that pointed out the importance of the Raman echo for studying condensed-phase vibrational dephasing (26). Initial attempts to perform the Raman echo in liquids failed (31), but technical improvements allowed the first successful Raman echo experiment in a liquid in 1991 (3). 

In many cases, the dynamics in low-viscosity liquids are sufficiently rapid to put vibrational dephasing in the fast modulation limit (73,85). However, several plausible mechanisms for producing slow modulation dephasing have... 

The FID results in toluene show the need for a theory of vibrational dephasing that works throughout the range from low-viscosity liquid to solid glass. It is also important that such a theory address the different roles of inertial and diffusive solvent dynamics explicitly. We developed the viscoelastic (VE) theory of vibrational dephasing to address these issues (8). 

Time-resolved coherent anti-Stokes Raman scattering has produced much important information on the dynamics of molecular vibrations and rotations (Laubereau and Kaiser, 1978 Duppen et al., 1983 Akhmanov et al., 1985 Angeloni et al., 1988). Particularly vibrational dephasing time constants in liquids and solids could be determined with this technique (Laubereau et al., 1978 Kohles and Laubereau, 1987 Weber and Rice, 1988 Bron et al., 1989). In these experiments pump and tunable Stokes beams serve to produce... 

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