Instrumentation for Generating Tunable VUV Radiation

Abstract

In this paper, we discuss a simple system (one dye laser and one pumping laser) constructed for generating tunable vacuum ultraviolet (VUV) radiation suitable for high resolution spectroscopy. Our special considerations are focused on the capability of generating hydrogen lyman-α at 121.6 nm and helium two-photon excitation radiation at 120.3 nm, and on the capability of monitoring both the intensity and the wavelength of the generated VUV radiation for precision spectroscopy. Third-order sum-difference frequency mixing, ωVUV = 2ωUV - ωir, is used to generate the VUV radiation in rare gases of Kr, Xe, and Ar. The input UV frequency is tuned near, but not on, two-photon intermediate resonances (Kr: 4p - 5p) to enhance the nonlinear susceptibility χ(3), and to provide the tunability of the VUV radiation. Operating near, but not on, intermediate resonances allows an efficient, tunable system with only one tunable laser. The optimal phase matching condition is achieved by mixing two oppositely dispersive gases [1 - 5].