E\crIatron of a-phr'nylbenzom solutron in accronitrde generates cmissron from thu drphcnyl hclyl radrcll with a Lfctimc oi 3.7 ns Thus IS quenched by methyl methaayhrc andp-chlorobcnzcncdiazonium tctrafluorobontc. The rate constant with dazomum salt is about the umc for Found and exncd radrals, whr
Room temperature fluorescence of the diphenyl ketyl radical
โ Scribed by K.Razi Naqvi; Urs P. Wild
- Publisher
- Elsevier Science
- Year
- 1976
- Tongue
- English
- Weight
- 541 KB
- Volume
- 41
- Category
- Article
- ISSN
- 0009-2614
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โฆ Synopsis
IViJitrogcn laser excitation of benzophenone solutions in some hydrogencontaining solvents generates emission from the diphenyl ketyI radical. In relatively unreactive solvents, a kety1 radical (produced by a benzophenone triplet) accepts energy fmm another benzophenone triplet; in highly reactive solvents, a ketyl radical produced during the laser pu!~ is excited by the absorption of a photon from the same pulse.
๐ SIMILAR VOLUMES
The lifetime of excited diphenyl ketyl radicals is lengthened by deuterium substitution. The largest effect is obyrved by substitution at the hydroxyllc positioni for example, the lifetimes are 3.9, 4.2, 8.7 and 10.5 ns for (C6H5)2COH, (C&)#OH, (C6Hs)2COD and (C&)2COD, respectively, in toluene or to
Fluorescence spectra and lifetimes have been measured at 77 K for the chalcone ketyl radical anion, and its hydroxy and methoxy derivatives. The radical anions were produced by y-irradiation of sample molecules at 77 K in alkaline polyvinyl alcohol films and in EPA rigid glasses with set-butylamine,
The diphenyl ketyl radical which is formed upon photolysis of a-phenyl benzoin is produced in its excited state upon intense pulsed laser irradiation. Using the techniques of time-resolved absorption and emission spectroscopy, reaction rate constants for the ground and excited states of this radical
irradiation of benzophcnone in isopropanol solution results in orange fluorescence, the yield of which depends on the laser pulse duration. This is shown to be due to benzophenone ketyl (hydroxydiphenyl methyl), formed as a photoproduct. It is shown that simple time-resolved fluorescence measurement
Using the technique of molecular modulation spectrometry, we have measured directly the rate constants of several reactions involved in the oxidation of methyl radicals at room temperature: (1) kl is in the fall-off pressure regime at our experimental pressures (20-760 torr) where the order lies b