Excited States of Lignin Aromatic Carbonyl Model Compounds

Excited States of Lignin Aromatic Carbonyl Model Compounds 

The aromatic carbonyl is an important structure in lignin photochemistry. The electronic structure of aromatic carbonyl compounds has been exhaustively studied [141], 

FIGURE 3.17 Jablonski (energy-level) diagram for a closed-shell molecule. Solid line transitions that occnr with absorption or emission of radiation dashed line radiationless transitions. 

A favorite model compound for photochemical studies is a-(2-methoxyphenoxy)- 

The lifetime of this triplet state is unusual for its longevity compared with other aromatic ketones and for its solvent dependence. The lifetime varies from about 200 ns in dioxane or acetonitrile, to 600 ns in 2-ethoxyethanol [144]. In contrast, the 

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