Infrared absorption of gaseous benzoylperoxy radical C6H5C(O)OO recorded with a step-scan Fourier-transform spectrometer

Abstract

A step-scan Fourier-transform infrared spectrometer coupled with a multipass absorption cell was utilized to monitor the transient species produced in gaseous reactions of benzoyl radical, C6H5CO, with O-2. C6H5CO was produced either from photolysis of acetophenone, C6H5C(O)CH3, at 248 nm, or from photolysis of a mixture of benzaldehyde, C6H5CHO, and Cl-2 at 355 nm. Two intense bands near 1830 and 1226 cm(-1) are assigned to the C=O stretching (nu(6)) and the C-C stretching mixed with C-H deformation (nu(13)) modes, and two weaker bands near 1187 and 1108 cm(-1) are assigned to the nu(14) (C-H deformation) and nu(16) (O-O stretching/C-H deformation) modes of C6H5C(O)OO, the benzoylperoxy radical. These observed vibrational wave numbers and relative infrared intensities agree with those reported for syn-C6H5C(O)OO isolated in solid Ar and values predicted for syn-C6H5C(O)OO with the B3LYP/cc-pVTZ method. The simulated rotational contours of the two intense bands based on rotational parameters predicted with the B3LYP/cc-pVTZ method fit satisfactorily with experimental results. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3664304]