The structure and spectra of organic peroxy radicals

Recent spectroscopic and computational work on organic peroxy radicals, RO2, is reviewed and extended with an emphasis on radicals where R is an alkyl group. Detailed experimental spectral, structural relationships are developed and show the dependence of spectral properties on the number of carbon atoms in the radical, and its isomeric and conformeric structure. These empirical relationships are explored and rationalized with the help of a series of quantum chemistry calculations, which are in turn benchmarked by the experimental data. The application of the spectra as a diagnostic for sensitive and selective measurement of radical concentrations for different RO2 species in an isomer- and conformer-specific manner is described. Future areas of research including investigation of additional peroxy species and high resolution spectra of cold radicals are discussed.