Experimental demonstration of a Raman scattering detector based on laser-enhanced ionization

We report what is to our knowledge the first experimental demonstration of detection of Raman photons by means of laser-enhanced ionization of magnesium atoms in an air-acetylene flame. A frequency-doubled dye laser was directed into a cell containing carbon tetrachloride. The resulting Stokes Raman photons were transferred into the flame, where they excited the magnesium atomic vapor into the 3p(1)P(1) state. The excited atoms were then pumped by another laser into the 5d(1)D(2) state, from which efficient collisional ionization occurred. We estimate a quantum efficiency of approximately 50% for the detector.