Photolytic interference affecting two-photon laser-induced fluorescence detection of atomic oxygen in hydrocarbon flames

This study reports on photochemical interferences affecting atomic oxygen detection using two-photon laser-induced fluorescence at 226 nm. In contrast to previous studies in which molecular oxygen was proven to be the relevant photochemical precursor molecule in a hydrogen-fueled flame, the present investigations were carried out in a laminar diffusion flame of methane and air. The most significant interferences were found at the fuel side of the flame in the absence of molecular oxygen, and vibrationally excited carbon dioxide was identified as the most probable precursor molecule for the photochemical production of oxygen atoms. Received: 11 December 2002 / Revised version: 10 March 2003 / Published online: 16 April 2003 RID="*" ID="*"Corresponding author. Fax: +1-925/294-2595, E-mail: tbsette@sandia.gov