Hydrostatic pressures, excited state rates

The purpose of outlining the decay pathways for this simple model (Fig. 6.1) is to emphasize that hydrostatic pressure can affect rates of the individual processes. Pressure can also affect energies of excited states relative to the ground state as well as relative to each other. 

A theoretical paper discusses the nature of solvent effects which affect the deactivation of A 02 . The effect of hydrostatic pressure on the radiationless deactivation of 03 in solution has also been reported . The perturbing effects of the solvents H2O, DjO, and QH5CH3 on the luminescence rate constant of O2 up to 100 atm provide evidence for pardcipation of complexes involving both the ground and excited states of molecular oxygen . The application of a collision complex model has been applied to the interpretation of photophysical quenching of 03 in liquids by 4-amino-TEMPO . 

Excited-State Kinetics. A principal emphasis of this chapter is concerned with how the application of hydrostatic pressures influences rates of ES processes such as those illustrated in Figure 9. In this simple model, it is assumed that electronic excitation leads efficiently to the formation of a single, bound state, which can decay by unimolecular radiative decay (rate constant kr), nonradiative decay (fc ), or chemical reaction to give products (kp). Alternatively, there may be bimolecular quenching of the ES dependent on the nature and concentration of some quencher Q (fcq [Q]). Each of these processes may be pressure dependent. 

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