Stimulated Raman shifting of the Nd:YAG fourth harmonic (266 nm) in H/sub 2/, HD, and D/sub 2/

The dependence of the first Stokes stimulated Raman conversion efficiency of fourth-harmonic radiation from a Nd:YAG laser at 266 nm has been studied for the isotopic species H/sub 2/, HD, and D/sub 2/ as a function of gas pressure and laser energy using a low numerical aperture ( approximately 4.5*10/sup -3/) pumping geometry. While the laser energy threshold for first Stokes conversion is seen to vary significantly between the species it has been found that photon conversion efficiencies of at least 50% can be achieved for all of them for laser pump energies at 266 nm >