Abstract

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 6<i>s</i>² ¹<i>S</i>₀-6<i>s</i>6<i>p</i> ¹<i>P</i>₁ 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 μg/mL barium, while a Doppler-free linewidth is maintained at 0.08 cm⁻¹, is reported.

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