Deactivation of the first excited singlet state of thiophenols.

摘要: On the bases of picosecond and nanosecond laser flash photolysis with detection by emission absorption spectroscopy, a quantitative description is given all deactivation channels first excited singlet state thiophenols ArSH(S1) such as fluorescence, intersystem crossing (ISC), chemical dissociation into radicals, radiation-less internal conversion (IC). For this purpose, thiophenol its methyl-, methoxy-, chloro-substituted derivatives was studied in solvents increasing polarity: 1-chlorobutane, ethanol, acetonitrile. The fluorescence lifetime found to range from some hundreds picoseconds up few nanoseconds, correlating quantum yields between 0.001–0.040, at room temperature. Depending on substitution pattern aromatic ring, yield S–H bond be 0.3–0.5, irrespective solvent polarity. In photolysis, no triplet formation investigated compounds could observed neither direct way nor subsequent sensitization β-carotene. As difference total, (ΦIC ≥ 0.5) dominating process.