Vibrational frequency heavy particle transfer

Naturally, neither of these approximations is valid near the border between the two regions. Physically sensible are only such parameters, for which b < 1. Note that even for a low vibration frequency Q, the adiabatic limit may hold for large enough coupling parameter C (see the bill of the adiabatic approximation domain in fig. 30). This situation is referred to as strong-fiuctuation limit by [Benderskii et al. 1991a-c], and it actually takes place for heavy particle transfer, as described in the experimental section of this review. In the section 5 we shall describe how both the sudden and adiabatic limits may be viewed from a unique perspective. 

There are no K(T) computations for specific reactions with heavy-particle transfer at present. In ref. 174 it is only noted that experimental values of K(0) ( 10 s ) for the reaction R -1- CI2 -> RCl -l- Cl correspond to the reasonable values of barrier height (0.2 eV) and intermolecular vibration frequencies (2 x 10 s ) at Rq = 3 A. The higher X(0) values, compared to H-transfer reactions, are explained by the decreased barrier height due to higher exothermicity of the reaction. Another example of the heavy-particle quantum transition is discussed in Section 5. 

A necessary condition for the two-term expansion of the distribution function of equation (2) to be valid is that the electron collision frequency for momentum transfer must be larger than the total electron collision frequency for excitation for all values of electron energy. Under these conditions electron-heavy particle momentum-transfer collisions are of major importance in reducing the asymmetry in the distribution function. In many cases as pointed out by Phelps in ref. 34, this condition is not met in the analysis of N2, CO, and C02 transport data primarily because of large vibrational excitation cross sections. The effect on the accuracy of the determination of distribution functions as a result is a factor still remaining to be assessed. 

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