Exchange approximations, vibrational modes

The Fe111/11 case is particularly simple. For electron transfer reactions in general, several normal modes may contribute to the trapping of the exchanging electron at a particular site. In addition, intramolecular vibrational modes are of relatively high frequency, 200-4000 cm-1, and at room temperature the classical approximation is not valid since only the v = 0 level is appreciably populated. In order to treat the problem more generally, it is necessary to turn to the quantum mechanical results in a later section. 

In considering the adatom-solvent interaction, we follow the theories of electron transfer reactions in solution (for a review, e.g., Ref.[166]) and distinguish between the librational and vibrational modes of the solvent, which are slow compared to the rate of electron exchange, and the polarizability of the solvent molecules. In the harmonic approximation, we can write for the slow solvent modes and their interaction with the adsorbate in the following expression... 

To complete the two-temperature approximation we should introduce vibrational kinetic relation controlling rates of e ( W -, and VT-relaxation processes and chemical reactions (Potapkin, Rusanov, Fridman, 1984a,b, 1987). They have to be considered as functions of the average number of vibrational quanta in CO2 symmetric valence mode ( i, quantum ftco ), CO2 symmetric deformation mode ( 2. quantum >2), CO2 asynunetric mode ( 3, quantum tws), and in CO vibrations (0(4, quantum <04). Rates of W -relaxation exchange between CO and CO2 molecules (rate coefficient k, ) and between asymmetric and symmetric modes of CO2 molecules in collisions with ar r i components of the mixture (rate... 

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