RESONANCE CARS OF OH IN HIGH-PRESSURE FLAMES

Resonance-enhanced coherent anti-Stokes Raman spectra of the OH radical have been obtained in a burner at high pressures up to 9.6 bar. Three separately tunable lasers were used to achieve optimal enhancement. The experimentally observed spectral profiles were fitted by using numerical computations. From these, collisional broadening parameters have been derived for one-photon transitions and for the ground and excited electronic state vibrational Raman transitions. Temperature measurements were made using OH spectra obtained by a slight detuning of a single pump-laser frequency. The vertical OH concentration profiles above the flame front were recorded from 1 to 9.6 bar. The sensitivity is sufficient to permit detection of OH in flames up to 30 bar with the present system and at still higher pressures with slight modifications of the experimental parameters. © 1990.