Vibrational trapping

In the classical limit where the condition << kgT is met for the trapping vibrations, the rate constant for electron transfer is given by eq. 6. In eq. 6, x/4 is the classical vibrational trapping energy which includes contributions from both intramolecular (X ) and solvent (XQ) vibrations (eq. 5). In eq. 6 AE is the internal energy difference in the reaction, vn is the frequen-... 

For the normal modes that contribute to vibrational trapping, AQe 0. If there is a series of such modes, X, is given by equation (22) where the summation is over all of the trapping vibrations. For the general case of unequal force constants, the contribution of the intramolecular vibrations to AG is not given by but rather by a more complex expression arising from the energy minimization procedure described in the derivation of equation (16a). 

The expression for Ke includes a rather elaborate correction for reversibility. It takes into account the fact that in the intersection region, there is no vibrational trapping. Electron transfer can occur back and forth between redox sites until vibrational redistribution removes the system from the intersection region. 

Other normal vibrations of the molecules may also be affected by the change in oxidation state but still not make a significant contribution to vibrational trapping. For example, for Fe(CN)6 / exchange in water there is a shift in (C—N) from 2094 cm for FeiCNg) " to 2132 cm for... 

This dependence of the H+ KE on the XUV-IR delay in this case of the longer, 35 fs FWHM, IR pulse can be understood in terms of the adiabatic-ity of the Floquet dynamics underlying the dissociation processes, and the way that the IR intensity affects both the preparation and the propagation of the Floquet components of the wavepackets. More precisely, the IR probe pulse projects the various vibrational components of the wavepacket onto Floquet resonances, whose widths vary with the intensity of the IR pulse. We recall that these resonances are of two types Shape resonances supported by the lower adiabatic potential defined at the one-photon crossing between the dressed (g, n), (u, n ) channels and leading to efficient dissociation through the BS mechanism, or Feshbach resonances, vibrationally trapped in the upper adiabatic potential well. 

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