STIMULATED RAMAN PUMPING TO H-2(UPSILON''=1,J''=1) AND RESONANCE-ENHANCED MULTIPHOTON IONIZATION FROM IT USING A SINGLE LASER

Light pulses from one ArF laser are used both a) to produce H2 in v″=1, J″=1 of the X-state by means of stimulated Raman pumping (SRP) and b) to analyze for that state via (2+1) resonance-enhanced multiphoton ionization (REMPI). Both SRP and REMPI have been previously measured in H2, but with a different laser for each process. Some of our laser light is Raman shifted in H2. The resulting mixture of fundamental (≈193 nm) and first Stokes (≈210 nm) light is focused into low-pressure H2 where the SRP and REMPI both occur. The SRP is efficient and it produces only v″=1, J″=1. As the laser is tuned, a REMPI spectrum occurs from excitation by two photons of 193 nm, by two photons of 210 nm, or by one photon each of 210 and 193 nm. The features of this approach are a) that the necessary temporal and spatial overlaps are automatically achieved, b) that the frequency difference generated in the Raman shifter is precisely that needed for SRP, c) that large pulse energies are available for the REMPI, and d) that only one laser is needed. © 1991 Springer-Verlag.