ULTRAVIOLET RAMAN-SCATTERING MEASUREMENTS IN FLAMES BY THE USE OF A NARROW-BAND XECL EXCIMER-LASER

Spectra with simultaneous peaks of CO2, O2, N2, CH4, and H2O are taken by the use of spontaneous Raman scattering from free jets and a turbu lent CH4 diffusion flame. A narrow-band XeCl excimer laser working at 308 nm and an intensified multichannel camera are used to give full in formation about all major species and the spectral background. Knowled ge of the structure of the background is important for data analysis. For O2, an enhancement that is due to near-resonant Raman scattering i s found. Assuming no influence of this enhancement on the temperature dependence of the O2 Raman-scattering cross section, temperature and c oncentrations of all major molecules are determined simultaneously fro m the intensity of the Raman bands. Experimental details and a data re duction scheme based on the analysis of the entire spectral shape are reported. Strong fluorescence backgrounds from OH radicals found in th e high-temperature regions of the flame are discussed.