Spectroscopy golden rule

Recently, the electron-transfer kinetics in the DSSC, shown as a schematic diagram in Fig. 10, have been under intensive investigation. Time-resolved laser spectroscopy measurements are used to study one of the most important primary processes—electron injection from dye photosensitizers into the conduction band of semiconductors [30-47]. The electron-transfer rate from the dye photosensitizer into the semiconductor depends on the configuration of the adsorbed dye photosensitizers on the semiconductor surface and the energy gap between the LUMO level of the dye photosensitizers and the conduction-band level of the semiconductor. For example, the rate constant for electron injection, kini, is given by Fermi s golden rule expression ... 

Other cases that require going beyond the golden-rule involve transitions which by their nature are of high order in the interaction. Processes studied in conjunction with nonlinear spectroscopy (see Section 18.7) are obvious examples. 

It is important to realize that the only approximations that enter into this rate expression is the use of the Fenni golden-rule, which is compatible with the weak coupling nonadiabatic limit, and the Condon approximation which is known to be successful in applications to electronic spectroscopy. The solvent effect on the electronic process, including the slow dielectric response, must arise from the FC factor that contains contributions from all the surrounding intermolecular and intramolecular nuclear degrees of freedom. In fact, if the nuclear component of the solvent polarization was the only important nuclear motion in the system, then on the classical level of treatment used by Marcus Eqs (16.53) and (16.51) with Ea given by (16.49) should be equivalent. This implies that in this case... 

Induced and spontaneous transitions in the two-level atom In the absence of a strong excitation field, which is the case with classical spectroscopy before the use of lasers, an induced transition between two levels would be described by the well-known Golden Fermi Rule based on first-order perturbation theory... 

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