Optical spectroscopy of perfluorothiophenyl, perfluorothionaphthyl, xanthate and dithiophosphinate radicals

Laser flash photolysis has been used to record the optical spectra of sulfu r-containing radicals forming from photodissociation of diphenyl disulfide, perfluorodiphenyl disulfide, perfluoro-2,2'-dinaphthyl disulfide, diisopro pyldixantogene and bis(diisobutylthio-phosphoryl-disulfane). The extinction coefficients of absorption bands were determined from the reaction of S-ra dicals with a stable nitroxyl radical. The rate constant of this reaction w as for all radicals close to 10(9) M-1 s(-1) and successfully competes with the reaction of recombination. The presence of a narrow and strong absorpt ion band in the optical spectrum of a nitroxyl radical and the absence of a bsorption in the reaction products allows one to accurately determine the e xtinction coefficients of the absorption bands of S-radicals. (C) 2000 Publ ished by Elsevier Science B.V.