Laser-induced fluorescence with tunable excimer lasers as a possible method for instantaneous temperature field measurements at high pressures: checks with an atmospheric flame.

A new method for instantaneous temperature field measurements based on LIF studies of OH, O(2), and H(2)O in an open atmospheric flame with a tunable excimer laser is suggested. In this method the crucial problem of quenching at higher pressures is almost completely eliminated by excitation to a fast predissociating state. The various possible excitation and fluorescence processes that can be induced in the narrow tuning range of the KrF laser are characterized experimentally by excitation and dispersion spectra for the three molecules OH, O(2), and H(2)O. Of particular importance is the large power of the KrF laser, which allows efficient excitation of even weak transitions. The fast predissociation of these molecules in connection with the powerful excitation laser suggests that instantaneous temperature field measurements should be possible at higher pressures.