Laser Spectroscopy of Atoms and Molecules Below 100 nm

For most atoms and molecules single photon excitation from the ground state to Rydberg states requires working in the vacuum ultraviolet (VUV). In recent years frequency upconversion of high power dye lasers has extended the application of laser spectroscopy into the VUV and even the windowless region below 104 nm, the extreme vacuum ultraviolet (XUV) [1]. In this work we generate XUV radiation by tripling the frequency of a frequency doubled dye laser in a free jet of the rare gases Ar and Xe [2]. In order to avoid unwanted UV multiphoton absorption processes in the sample under investigation we separate the third harmonic XUV beam from the collinearly propagating high power fundamental UV light in a dichroic beam splitter set-up. The XUV is focussed into an atomic or molecular beam for studying the photoexcitation, ionization or fragmentation of the species.