Frequencies, molecular

Ulness D J, Stimson M J, Kirkwood J C and Albrecht A C 1997 Interferometric downconversion of high frequency molecular vibrations with time-frequency-resolved coherent Raman scattering using quasi-cw noisy laser light C-H stretching modes of chloroform and benzene J. Rhys. Chem. A 101 4587-91... 

As reviewed above, there have been many QELS studies on liquid surfaces. However, until a few years ago, reports were scarce on molecular dynamics at liquid-liquid interfaces which used time courses of capillary wave frequency. Molecular collective behavior at liquid-liquid interfaces from a QELS study was first reported by Zhang et al. in 1997 [5]. 

A simple model for collective high-frequency and low-frequency molecular modes... 

To determine the characteristics of the 2x1 phase in the system CO/NaCl(100) from general formulae (4.3.47), we equate expressions (4.3.47) and (4.3.48) thus deriving four equations in four unknown parameters, y, ij and A ty with j = S, and A. It is noteworthy that for the spectral lines associated with local vibrations S and A, the vector k assumes two values k = 0 and k = kA (kA is a symmetric point at the boundary of the first Brillouin zone). The exact solution of the system of equations provides parameter values listed in Table 4.3.187 The same parameters were previously evaluated by formulae (4.3.49) without regard for lateral interactions of low-frequency molecular modes." As a consequence, the result was physically meaningless the quantities y and t] proved to be different for vibrations S and A (also see Table 4.3). 

The most pronounced relaxation phenomena (in terms of field dependence) were to be expected at relatively low fields where low-frequency molecular motions can have a very large impact on the longitudinal relaxation times Ti. 

Dcinerdache. A. and R.H. Wright "Low-Frequency Molecular Vibration in Relation lu Odor," in Olfaction and Taste (T. Hayaski, editor). Vo] 2, Pergatnon, Elrmfnrd, New York, NY. 1979. 

It is interesting to note that this is of the same order of magnitude as the period of a low-frequency molecular vibration. For real molecules Vr will be larger than average thermal velocities because of the increase in velocity due to attractive forces. 

In the Sumi-Marcus (SM) model 13a], the perspective is changed, with a TST rate constant based on a low-frequency molecular mode (m) as the reaction coordinate, and with G dependent on a diffusive solvent coordinate X. For ease of comparison with other models, we transform X (relative to its definition in [13a]) so as to correspond to a continuous charging parameter (X = 0 for the bottom of the reactant well, and X = 1 for the bottom of the product well for the case of parabolic free energy profiles the transformation is linear the more general situation is dealt with in [98]). Also, 7.ci = A + z , and /.d = a, , where 7, , is the reorganization energy associated with the low-frequency mode m. These definitions lead to the following equation ... 

Boutin, H., H. Prask, S. F. Trevino, and H. Danner Study of the low-frequency molecular motions in polyethylene and the -paraffins by slow neutron inelastic scattering. Proceedings of Symposium on Inelastic Scattering of Neutrons, Bombay, Dec. 1964, Vol II, 407—419 pp. I. A. E. A., Vienna, 1965. 

The vibrational frequencies, molecular structure and constants were taken from Mann and Fano (3). The barrier restricting internal rotation about the B-B single bond is fixed at 1.53 0.60 kcal raol" obtained from Mason and Kreevoy (4) The reduced... 

The mclusion of high-frequency molecular modes in the spirit of Eq. (16.62) is critical for the quantitative aspects of this behavior, in particular in the inverted regime (see Fig. 13 in the Review by Bixon and Jortner cited at the end of this chapter). 

Under the influence of the applied gradients and the thus effected space dependence of the Larmor frequencies, molecular migration leads to a decrease of the signal intensity. The echo attenuation due to diffusion becomes (cf., e.g., (6,S-i0))... 

The most reactive atoms in a molecule are those that are involved in high frequency molecular motions. 

For inverted-region ET, the rate was almost completely independent of temperature. This result was in strong contrast to the predictions of classical Marcus theory, but in excellent agreement with quantum mechanical modifications that include the effects of high-frequency molecular vibrations in the donor and acceptor groups. 

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