Mid-Infrared Spectrum of the Gas-Phase Ethyl Peroxy Radical: C2H5OO

Abstract

The mid-IR spectrum of gas-phase C2H5OO has been measured over the spectral range of 800−4000 cm-1. The employed experimental technique was long-path-length absorption in which a White cell was coupled to an FTIR spectrometer. Radicals were generated in a mixing manifold prior to the absorption cell by passing an F2/He mixture through a microwave discharge to create fluorine atoms followed by the reaction of atomic fluorine with an ethane/oxygen mixture. A number of absorption bands were observed to increase in intensity with increasing atomic fluorine concentration. Verification that the observed bands originated from the ethyl peroxy radical was done first by comparing measured band frequencies with the spectra of possible secondary reaction products and second by titrating C2H5OO• with excess nitric oxide and observing the nitrogen dioxide and ethyl nitrite products that ultimately result from the titration reaction. Bands were assigned to normal modes of C2H5OO• through comparing the observed band positions and intensities to the results of ab initio calculations and to the previous work of Chettur and Snelson (Chettur, G.; Snelson, A. J. Phys. Chem. 1987, 91, 3484) and Pushkarsky, Zalyubovsky, and Miller (Pushkarsky, M.B.; Zalyubovsky, S. J.; Miller, T. A. J. Chem. Phys. 2000, 112, 10695).