Light, absorption energy

The effects of increased solvent polarity on the light absorption energy from the ground to the (Franck-Condon) excited state can be hypsochromic, if the ground state is more stabilized than the excited state or bathochromic if the opposite relative stabilization takes place. 

Cytec s family of light stabilizers includes Cyasorb UV absorbers, which prevent photo-degradation of polymers by competitive UV light absorption, energy quenchers, radical scavengers, and hydroperoxide decomposers. 

Fig. 4. Chemistry of poly(vinyl cinnamate) negative-acting resist. Initial light absorption by the photosensitizer is followed by energy transfer to produce a pendant cinnamate group in a triplet electronic state. This combines with a second cinnamate on another polymer chain, forming a polymer—polymer...

Because, in principle, transitions can occur on light absorption to any of the many possible energy levels of the excited state from any one of the many possible energy levels of the ground state, the absorption spectmm of a chromogen at room temperature or above is virtually continuous. 

In these dye-functionalized dendrimers, light absorbed by the numerous peripheral coumarin-2 units is funneled to the coumarin-343 core with remarkably high efficiency (toluene solution 98% for the first three generations 93% for compound 8). Given the large transition moments and the good overlap between donor emission and acceptor absorption, energy transfer takes place by Forster mechanism [34]. 

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