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PHOTOIONIZATION OF MELANIN PRECURSORS: AN ELECTRON SPIN RESONANCE INVESTIGATION USING THE SPIN TRAP 5,5‐DIMETHYL‐1‐PYRROLINE‐1‐OXIDE (DMPO)
Author(s) -
Kalyanaraman B.,
Felix C. C.,
Sealy R. C.
Publication year - 1982
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.1982.tb04332.x
Subject(s) - photoionization , chemistry , photochemistry , radical , electron paramagnetic resonance , free radical scavenger , scavenger , electron , spectroscopy , spin trapping , ionization , nuclear magnetic resonance , ion , organic chemistry , antioxidant , physics , quantum mechanics
The photoionization of 3,4‐dihydroxyphenylalanine (dopa) and catechol has been studied by electron spin resonance spectroscopy using the free radical scavenger 5,5‐dimethyI‐1‐pyrroline‐1 ‐oxide as a spin trap for hydrated electrons and hydrogen atoms. The photochemistry of these materials is shown to resemble tyrosine in that both photoionization and photohomolysis (to give H) occur, with photoionization predominating (by a factor of 2.6 for dopa). Ionization of one of the phenolic hydroxyl groups increases the yield of radicals by a factor of 2. Action spectra and quantum yields for radical production are reported.