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

TLDR

The high power of the KrF excimer laser enables efficient excitation of even weak transitions. The study proposes a new LIF-based method using a tunable excimer laser to measure instantaneous temperature fields in an atmospheric flame. By exciting OH, O₂, and H₂O to a fast predissociating state with the KrF laser, the method eliminates quenching at high pressures and characterizes excitation and fluorescence processes through excitation and dispersion spectra. Fast predissociation of these molecules, together with powerful excitation, indicates that instantaneous temperature field measurements should be possible at higher pressures.

Abstract

A new method for instantaneous temperature field measurements based on LIF studies of OH, O2, and H2O 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, O2, and H2O. 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.