Doppler-free two-photon-excited fluorescence spectroscopy of atomic hydrogen in flames

Abstract
We describe Doppler-free 205-nm two-photon excitation studies of atomic hydrogen performed using a single-mode pulsed dye-laser system in low-pressure flames. Excitation spectra confirm calculated line-strength ratios for transitions to the 3S and 3D states. Collisional broadening rates are obtained in several flames and compared with quenching rates measured in the same flames, using time-resolved fluorescence measurements.