RAMAN FREQUENCY-SHIFTING IN A CH4-H-2-AR MIXTURE PUMPED BY THE 4TH HARMONIC OF A ND-YAG LASER

Mixtures of methane, hydrogen, and argon (CH4:H-2:Ar) were studied as UV Raman shifters for ozone differential absorption lidar application. They have higher photochemical stability than pure CH4 and the capabi lity to produce, with high enough efficiency, either first CH4 Stokes or, simultaneously, CH4 and H-2 first Stokes with equal energies. Thes e mixtures can he used as an inexpensive replacement for D-2 or a more stable substitute for pure CH4 in single-pass high-power Raman shifte rs. (C) 1998 Optical Society of America.