Characterization of a UV prism compressor for UV-IR pump-probe experiments*

We report on the characterization of a setup for UV-IR pump-probe experiments on gas-phase molecules using third-harmonic generation (THG) of a Ti:Sapphire laser. Using a Calcium Fluoride prism compressor, we have been able to reduce the UV (266 nm) pulse duration in the interaction region from 100 fs to \textless 50 fs. We measure these pulse durations via cross-correlation of the UV pulse with the fundamental IR using a difference-frequency generation (DFG) crystal, as well as a cross-correlation in Ar gas using a cold target recoil ion momentum spectrometer (COLTRIMS). Results of the pulse characterization will be presented along with data on the time-dependent UV-induced photodissociation of CH$_{\mathrm{3}}$I.