Generation Of VUV - Radiation By Means Of Excimer-Lasers And Application To Fluorescence Diagnostics

Abstract

UV-excimer lasers have proven to be interesting sources for applications in the field of nonlinear optics, photochemistry and spectroscopy because of both their high pulse energy and high average power. In addition, they allow tuning over a wide range due to the relatively broad fluorescence bandwidth of several hundred wavenumbers. We report on generation of tunable radiation around 193 nm (ArF) and 248 nm (KrF) by Raman-shifting of dye laser radiation (ArF, KrF) or second harmonic generation (KrF) and subsequent amplification in excimer laser sections. Measurements of resulting energies and tuning ranges are presented. The beam quality and power density of the amplified radiation is suitable to the generation of tunable VUV radiation by stimulated anti-Stokes Raman-scattering in H2 down to 116 nm. This VUV radiation allows many applications in atomic and molecular physics. As an example, we present results of concentration- and velocity distribution measurements of 0-, Be- and C-atoms by laser-induced fluorescence spectroscopy. An alternative method to generate high-power VUV radiation with the aid of excimer lasers is two-photon pumping of H2 with 193 nm-radiation (ArF). Emission of laser radiation on more than 20 transitions is observed in the Lyman and Werner bands between 160 nm and 117 nm. We compare results obtained using the same set-up as for the Raman shifting mentioned above with results obtained using a commercial oscillator-amplifier ArF laser source.