Optical spectroscopy of perfluorothiophenyl, perfluorothionaphthyl, xanthate and dithiophosphinate radicals

Laser flash photolysis has been used to record the optical spectra of sulfur-containing radicals forming from photodissociation of diphenyl disulfide, perfluorodiphenyl disulfide, perfluoro-2,2′-dinaphthyl disulfide, diisopropyldixantogene and bis(diisobutylthio-phosphoryl-disulfane). The extinction coefficients of absorption bands were determined from the reaction of S-radicals with a stable nitroxyl radical. The rate constant of this reaction was for all radicals close to 109 M−1 s−1 and successfully competes with the reaction of recombination. The presence of a narrow and strong absorption band in the optical spectrum of a nitroxyl radical and the absence of absorption in the reaction products allows one to accurately determine the extinction coefficients of the absorption bands of S-radicals.