Polarization rejection of scattered incident laser light in resonance fluorescence flame atomic detection

In the detection of trace atomic species by resonance fluorescence, scattering of the incident light may cause a significant interference. Fluorescence detection of flame atomized sodium in the presence of intense scattering resulting from the combustion of aluminium in an air-acetylene flame was investigated. A linearly polarized cw dye laser was used as the excitation source. Due to the high polarization of the scattered light, insertion of a polarizer in the detection optics allowed effective rejection of this interference. Improvements in the signal-to-noise and background ratios of 460 and 200, respectively were observed upon introduction of the polarizer. Further improvement was observed employing harmonic saturated spectroscopy.