OH LASER-INDUCED FLUORESCENCE AT HIGH-PRESSURES - SPECTROSCOPIC AND 2-DIMENSIONAL MEASUREMENTS EXCITING THE A-X(1,0) TRANSITION

Laser-induced fluorescence (LIF) spectra of OH were recorded in the ex haust of a laminar premixed methane/air flame in the pressure range be twen 5 and 36 bar. The OH A-X (1,0) transition near 280 nm was excited . From these spectra, temperatures and effective collisional broadenin g coefficients were determined by means of a detailed simulation progr amm. The strong dependence of the pressure broadening coefficient on t he rotational quantum number had to be accounted for, in order to avoi d systematic errors in the temperature determination. Strategies for t emperature measurements at high pressures by two line measurements are presented. In order to demonstrate the applicability of the detection scheme discussed here for high-pressure applications, single-pulse tw o-dimensional measurements of the OH distribution at 36 bar are presen ted, as well as an averaged temperature distribution.