Photochemical reactions Rydberg states

Since most known photochemical reactions occur at the lowest excited states of molecules a Rydberg state will be photochemically important if it is one of the lowest excited states of the given molecule. This will be especially true if it is actually the lowest of them. Now, on the basis of a great amount of experimental and theoretical knowledge accumulated during the last ten years we might sum up the situation as follows. 

At this stage one might ask if there is any connection between the Rydberg or valence-shell character of the orbital of the excited electron and Woodward and Hoffnian s and Salem s scheme of interpretation of photochemical reactions " In the words of Dauben, Salem and Turro the latter is based on the assumption that . .. all photochemical processes are controlled by generation of primary products which have the characteristics of diradicals . The states of the diradicals which they consider are the typical diradical states and with the... 

The radial distribution of this orbital is large in comparison with the 2p orbitals that are the basis set for the n orbital. In essence, this is an orbital around the entire molecule. ° ° Moreover, internal conversion of the n,a, Rydberg, and k,tz states of alkenes is slow. These states may therefore exhibit their own characteristic photochemical reactions, so there can be si hcant wavelength effects on the distribution of photochemical products. ... 

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