Excited states of photosensitive groups

TSUDA AND oiKAWA Excited States of Photosensitive Groups... 

Few reports(, 11 ) have been published on the electronicstates of cinnamoyloxy group although there are many of those on the photochemical reactions ). In this paper, the electronic structures in the excited states of cinnamoyloxy group are clarified by the molecular orbital calculations and the spectroscopic procedures, and discussed in connection with the intensity of light absorption, photochemical reaction processes and energy transfers in the sensitization which are important in the comprehensive understanding of the photosensitive polymer. 

Electronic Structures in the Excited States of the Photosensitive Groups of Photocrosslinkable Polymers. (I) Polyvinyl dnnamate... 

Studies [126] of electronic structures in photo-isomerization and photo-dimerization of cinnamic acid showed that phosphorescence of cinnamic groups occurs at about 20,000/cm. Also, it was demonstrated when photo sensitizers are present, the critical distance between donor, sensitizer, and acceptor molecules (cinnamic acid) is about 10 A [126]. Although all the details of incipient photocross-linking of poly(vinyl cinnamate) have to date stUl not been fully worked out, most accept that all three mechanisms take place. These are dimerizations to truxillic and truxinic acid type structures and polymerizations through the double bonds. The excited states of the molecules can be produced by direct irradiation and also through intersystem crossing from an appropriate photosensitizer [126]. 

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