Intramolecular vibrational energy transfer

Uzer T 1991 Theories of intramolecular vibrational energy transfer Rhys. Rep. 199 73-146... 

T. Uzer, Phys. Rep., 199, 73 (1991). Theories of Intramolecular Vibrational Energy Transfer. 

Beckerle JD, Cavanagh RR, Casassa MP, Heilweil EJ, Stephenson JC. Subpicosecond study of intramolecular vibrational energy transfer in solution-phase Rh(CO)2acac. Chem Phys 1992 160 487-496. 

The second part of the chapter (Section III) deals with the time-dependent self-consistent-field (TDSCF) method for studying intramolecular vibrational energy transfer in time. The focus is both on methodological aspects and on the application to models of van der Waals cluster systems, which exhibit non-RRKM type of behavior. Both Sections II and III review recent results. However, some of the examples and the theoretical aspects are presented here for the first time. 

Single vibrational levels of the 82 state of aniline, formed by excitation within a He-aniline molecular beam, have been shown to relax in low-energy collisions with the He diluent at rates which are markedly dependent upon the identity of the vibrational mode excited. Intramolecular vibrational energy transfer within the 82 state induced by collision with HjO and CH3F is also mode specific, and rates for these processes are of the same order for these two collision partners and considerably faster than for energy transfer caused by Ar. Within p-alkylanilines, collisionless intramolecular vibrational relaxation from the initially excited NHj inversion mode to the alkyl chain modes appears to be complete within 1 ns, ... 

Straub J E and Berne B J 1986 Energy diffusion in many-dimensional Markovian systems the consequences of competition between inter- and intramolecular vibrational energy transfer J. Chem. Phys. 85 2999-3006... 

Collision-induced intramolecular vibrational energy transfer is restricted to a small subset of the levels in the energetically accessible range. 

Fig. 2. The pathways for collision-induced intramolecular vibrational energy transfer from the 6 level of benzene. The figures entered are the cross-sections relative to the hard sphere collision cross-section. Collision partner He.

Slater [13] has criticized the RRKM theory, mainly on the grounds that the proposed model assumes that the intramolecular transfer of energy between vibrational degrees of freedom is very rapid compared to the rate of reaction. In fact, all theories of unimolecular reactions, aside from Slater s, involve this particular assumption. Slater assumes that the rate of intramolecular vibrational-energy transfer is very slow. He then performs a normal-mode analysis of the reacting molecule, assuming that reaction occurs when the bond to be broken reaches a certain critical length. A formally correct expression for is obtained, namely. 

Several recent studies suggest that the basic assumption of the RRKM theory of rapid intramolecular vibrational-energy transfer is, in fact, essentially correct. For example, several cases have been well documented where the experimental results are contrary to those predicted from physical assumptions of Slater s theory [14]. Butler and Kistiakowsky [15] studied the isomerization of vibrationally excited methylcyclopropane molecules formed by two different chemical reactions (I). 

K. G. Kay, Numerical study of intramolecular vibrational energy transfer Quantal, classical, and statistical behavior, J. Chem. Phys. 72 5955 (1980). 

D. C. Tardy and B. S. Rabinovitch, Intramolecular vibrational energy transfer in thermal unimolecular systems, Chem. Rev. 77 369 (1977). 

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