IR and UV spectra of the matrix-isolated peroxy radicals CF3OO, trans-FC(O)OO, and cis-FC(O)OO

The peroxy radicals CF3OO and FC(O)OO are prepared in high yields by vacuum flash pyrolysis of ROO-NO2 or ROOOR (R = CF3, FC(O)), highly diluted in in ert gases, and subsequent isolation in inert-gas matrices by quenching the product mixtures at low temperatures. The IR spectrum of FC(O)OO was observ ed for the first time and eight fundamentals as well as several combination s were measured and assigned for both cis and trans rotamers of FC(O)OO Dis crepancies in an earlier assignment of the fundamentals of CF3OO have been eliminated and its IR spectrum is reported fully The matrix UV spectra of b oth peroxy radicals (X(2)A" --> 2(2)A" transition) are in agreement with th e gas-phase spectra; however, there are differences in the absorption cross -sections, for which possible reasons are discussed. The X(2)A"-->1(2)A' tr ansitions in the near IR region are too weak to be detected with our instru mentation.