Pyrene photodecomposition

Payne [30] carried out a field investigation of benzopyrene hydrolysate induction as monitor for marine petroleum pollution. Isaaq et al. [31] isolated stable mutagenic ultraviolet photodecomposition products of benzo(a)pyrene by thin-layer chromatography. 

All the 1-pyrenylbismuthonium salts photochemically decompose (2ex > 320 nm / > 150 mW cm 2) to generate their respective protic acids, accompanied by the formation of bismuth(III) compounds and pyrene (Scheme 25). The quantum yields of the photodecomposition (<7>dcc) in acetonitrile were determined by chemical actinometry to be 0.20-0.22. These values are comparable to the values reported for the triarylsulfonium and diaryliodonium salts (dec = 0.17-0.22) [98, 99]. 

Fig. 11. Luminescence of impurities in ethanol at 20°C. sensitized by 10 Mf phenanthrene. Rate of light absorption was 0.7 X 10- einstein liter-1 sec.-1 at 341 to 362 mji. (a) normal fluorescence (b) and (c) delayed fluorescence at 1000 times greater sensitivity (d) fluorescence of dilute pyrene solution. Photodecomposition of (i>) to give (c) was produced by irradiation for 30 min. with rate of light absorption equal to 10 - einstein liter-1 sec.-1.

Penetration of light. Poly(methyl methacrylate) film doped with a high concentration of pyrene shows well defined ablation. Small curd-like particles are observed for a film with a low dopant concentration. The origin of these particles can be explained by the low density and inhomo-genous distribution of bond scission in the polymer subsurface during ablative photodecomposition with an increase in beam penetration [1417]. 

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