ABSTRACT
The quantum yield for disappearance of 2-(2-hydroxy-5-methylphenylbenzotriazole (Tinuvin P) in dimethyl sulfoxide (DMSO) solution was highly dependent on wavelength varying from 2.6 x 10 -4 at 290 nm to 0.4 x 10 -4 at 350 nm (21). The plot of quantum yield versus wavelength was coincident with the absorption spectrum calculated for the "open," nonintramolecularly hydrogen-bonded form of the UVA, suggesting that the photochemistry arose from the open form.
