Nonradiative transitions photochemistry

The lowest vibrational energy levels of a state are indicated by thick horizontal lines other horizontal lines represent associated vibrational levels. Vertical straight lines represent radiative transitions, wavy lines nonradiative transitions. The orders of magnitude of the first-order rate constants for the various processes are indicated. From R. B. Gundall and A. Gilbert, Photochemistry, Thomas Nelson, London, 1970. Reproduced by permission of Thomas Nelson and Sons Limited. 

A large amount of spectroscopic data are now available for benzene, providing much information on photophysics and photochemistry properties of the lowest excited states of this molecule. Nevertheless the nature of the various radiative and nonradiative transitions involved in the deexcitation of the first excited states is far from being completely understood. 

Figure 3.17 Excited-state photochemistry of free 2 and hypothesized primary pathway of the antibody—2 complexes (gray). Dashed lines nonradiative transition solid lines radiative transitions. FC Franck-Condon excited state [64].

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