Vibrational redistribution, intramolecular

Tannor D J, Rice S A and Weber P M 1985 Picosecond CARS as a probe of ground electronic state intramolecular vibrational redistribution J. Chem. Phys. 83 6158... 

Beil A, Luckhaus D, Quack M and Stohner J 1997 Intramolecular vibrational redistribution and unimolecular reactions concepts and new results on the femtosecond dynamics and statistics in CHBrCIF Ber. Bunsenges. Phys. Chem. 101 311-28... 

Mukamel S and Shan K 1985 On the selective elimination of intramolecular vibrational redistribution using strong resonant laser fields Chem. Rhys. Lett. 5 489-94... 

Nesbitt D J and Field R W 1996 Vibrational energy flow in highly excited molecules role of intramolecular vibrational redistribution J. Rhys. Chem. 100 12 735-56... 

Marquardt R and Quack M 1991 The wavepacket motion and intramolecular vibrational redistribution... 

In order to define how the nuclei move as a reaction progresses from reactants to transition structure to products, one must choose a definition of how a reaction occurs. There are two such definitions in common use. One definition is the minimum energy path (MEP), which defines a reaction coordinate in which the absolute minimum amount of energy is necessary to reach each point on the coordinate. A second definition is a dynamical description of how molecules undergo intramolecular vibrational redistribution until the vibrational motion occurs in a direction that leads to a reaction. The MEP definition is an intuitive description of the reaction steps. The dynamical description more closely describes the true behavior molecules as seen with femtosecond spectroscopy. 

In highly exothermic reactions such as this, that proceed over deep wells on the potential energy surface, sorting pathways by product state distributions is unlikely to be successful because there are too many opportunities for intramolecular vibrational redistribution to reshuffle energy among the fragments. A similar conclusion is likely as the total number of atoms increases. Therefore, isotopic substitution is a well-suited method for exploration of different pathways in such systems. 

The surface in Fig. 12 demonstrates that there is little coupling between the C—F translation coordinate and the bending coordinate of the complex. Stated another way, the time scale for intramolecular vibrational redistribution between these coordinates is slow compared to the time scale for breaking the C—F bond. These conclusions are not obvious upon examination of the minimum energy path shown in Fig. 11, and indeed such diagrams, while generally instructive, can lead to improper conclusions because they hide the multidimensional nature of the true PFS. A central assumption of statistical product distribution theories... 

Highly Excited Molecules Role of Intramolecular Vibrational Redistribution. 

The combination of low-resolution and spectral unzipping into noninteracting polyads enables systematic, model-free surveys of deperturbed Franck-Condon factors, deperturbed zero-order energy levels, and trends in intramolecular vibrational redistribution (IVR) rates and pathways [3]. The H[ res,/i polyad model permits extraction of the most important resonance strengths directly from fits to a few polyads [6-8]. Once these anharmonic... 

Figure 23 A proposal for dephasing in ethanol by solvent-assisted intramolecular vibrational redistribution (IVR). The yym-methyl stretch is initially excited, but rapidly equilibrates with one or more modes within kT (the ayym-methyl stretch and/or CH bend overtones). Dephasing occurs with this rapid equilibration time Tivr- However, significant population remains in the sym-methyl stretch after equilibration. Relaxation from this group of state to lower states causes the final relaxation of the population to zero, which is measured as Tj in energy relaxation experiments. (Adapted from Ref. 7.)...

This chapter is concerned with how energy deposited into a specific vibrational mode of a solute is dissipated into other modes of the solute-solvent system, and particularly with how to calculate the rates of such processes. For a polyatomic solute in a polyatomic solvent, there are many pathways for vibrational energy relaxation (VER), including intramolecular vibrational redistribution (IVR), where the energy flows solely into other vibrational modes of the solute, and those involving solvent-assisted processes, where the energy flows into vibrational, rotational, and/or translational modes of both the solute and the solvent. 

Spectroscopic studies have identified a range of time scales for intramolecular vibrational redistribution (IVR) in molecules, large and small, all the way from... 

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