Photochemistry of thioxanthones—I. Spectroscopic and flash photolysis study on oil soluble structures

摘要: Abstract The photochemistry of three water soluble thioxanthone photoinitiators is studied in using absorption, luminescence (fluorescence and phosphorescence) conventional microsecond flash photolysis techniques. Longest wavelength absorption maxima extinction coefficients are similar to those the oil types earlier. fluorescence phosphorescence properties, on other hand, differ significantly. In this case, certainly for two initiators, high very low quantum yields observed, former being effectively quenched by addition a tertiary amine, diethylmethylamine. End-of-pulse transient spectra show presence weakly absorbing semiquinone type radical at ∼ 340 nm formed hydrogen atom abstraction. formation due neutral ketyl significantly enhanced coupled with new band longer wavelengths, 480–510 nm, anion electron transfer. oxygen, particularly abstraction little affected consistent data, suggesting that these initiate free via singlet state. significance results, contrast types, discussed.