Electronic spectra of radicals in a supersonic slit-jet discharge by degenerate and two-color four-wave mixing

Abstract

Four-wave mixing techniques have been used for the measurement of electronic transitions of cold transient species generated in a supersonic slit-jet discharge expansion. The origin band of the d³Π_g–a³Π_u system of C₂ and òΠ_3/2–²Π_3/2 electronic transition of HC₄S were recorded. A signal-to-noise ratio of 10⁴ in the spectra was achieved, resulting in detection limits of 10¹⁰ cm⁻³ for these two molecules. Application of selective two-color resonant four-wave mixing is used for the spectral assignment utilizing the double-resonance nature of the method. The combination of these techniques with a slit source proves to be a sensitive approach for the detection of transient molecules in a molecular beam discharge.