Degenerate vibrations kinetic energy

Figure 6.12 Free energy correlation (shown schematically) for the H and D zero-point vibrations for a degenerate stepwise double hydrogen transfer reaction according to Eq. (6.31), where secondary kinetic isotope effects and isotopic fractionation between the initial and the intermediate state were neglected. Adapted from Ref [18c],...

Degenerate energy-transfer mechanisms may be thought of as collections of physically distinct kinetic processes that lead to the same vibrational temperature distribution. An example of such a degenerate set for CHjF is... 

VT relaxation in molecular collisions with atoms and radicals can be illustrated by relaxation of vibrationally excited N2 on atomic oxygen (Andreev Nikitin, 1976 see Fig. 2-35). The interval between degenerated electronic terms grows when an atom approaches the molecule. When the energy interval becomes equal to avibrational quantum, non-adiabatic relaxation (the so-called vibronic transition, Fig. 2-35) can take place. The temperature dependence of this relaxation is not significant, and typical rate coefficients are high lO -lO cm /s. Sometimes, as in the case of relaxation on alkaline atoms, the non-adiabatic VT-relaxation rate coefficients reach those of gas-kinetic collisions, that is, about 10 ° cm /s. 

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