Comparison of radical generation efficiencies of the oxime-based initiator radicals using galvinoxyl radical as an indicator

The absolute quantum efficiency of free radicals is one of the most important primary parameters in UV curing processes initiated by photoradical initiators. Herein, a novel experimental protocol has been developed to evaluate the radical generation yield of photoinitiators upon UV irradiation using...

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Bibliographic Details
Published in:Japanese Journal of Applied Physics 2018-08, Vol.57 (8), p.86504
Main Authors: Tsuneishi, Asuka, Sakamaki, Daisuke, Gao, Qi, Shoda, Takayuki, Kozawa, Takahiro, Seki, Shu
Format: Article
Language:English
Subjects:
Free radicals
Initiators
Oxidation
Photoinitiators
Process parameters
Quantum efficiency
Ultraviolet radiation
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Summary:The absolute quantum efficiency of free radicals is one of the most important primary parameters in UV curing processes initiated by photoradical initiators. Herein, a novel experimental protocol has been developed to evaluate the radical generation yield of photoinitiators upon UV irradiation using a galvinoxyl radical as an indicator. The absolute quantum efficiency of free radical generation was determined by this method for six different photoinitiators. The yields were in good agreement with the results of theoretical calculations, where the rate of intersystem crossing was revealed to be the determinant step for the resultant radical generation yield. In particular, note that the high quantum yield of initiators could be attainable in the design of a molecule with an efficient intersystem crossing from the first singlet excited state (S1: nπ*) to the second triplet excited state (T2: ππ*).
ISSN:0021-4922
1347-4065
DOI:10.7567/JJAP.57.086504