DOPPLER-FREE SPECTRUM OF THE BARIUM S-1(0)-P-1(1) TRANSITION BY DEGENERATE 4-WAVE-MIXING USING AN AIR ACETYLENE FLAME

Doppler-free flame spectrometry based on resonant degenerate four-wave mixing (D4WM) is shown to be an effective analytical tool for the determination of barium at high spectral resolution. Optical phase conjugation is produced in an air/acetylene flame, resulting in an optical signal that is a coherent time-reversed replica of the probe beam. The degenerate four-wave mixing spectrum of barium for the 6s21S(o)-6s6p 1P1 transition at 18,060.19 cm-1 is collected with a linewidth of 0.08 cm-1 (FWHM) with the use of a convenient continuously flowing atmospheric-pressure flame atomizer. A preliminary detection limit of 5-mu-g/mL barium, while a Doppler-free linewidth is maintained at 0.08 cm-1, is reported.