A MODEL FOR THE TEMPERATURE-DEPENDENCE OF THE NEAR UV ABSORPTION-SPECTRA OF ORGANIC PEROXY-RADICALS

A Gaussian approximation, based on the sum rules that apply for allowe d electronic transitions, is used to model room-temperature and high-t emperature absorption data for three organic peroxy radicals. For HO2, the absorption spectra calculated from the model are in good agreemen t with available experimental data for temperatures in the range 300-1 100 K. For CH3O2 and C2H5O2, there is again good agreement between the experimental and calculated spectra at room temperature. A satisfacto ry fit to the high-temperature data for these two species can also be achieved if the integrated band strength of the experimental data is i ncreased by 10-15%, suggesting a systematic error in the normalization procedure used in finding the experimental cross sections. The use of the fitting parameters obtained from the sum rule model to obtain inf ormation about the excited electronic state potential of RO(2) radical s and limitations of the present;model are also discussed.