The design and construction of a solid state femtosecond laser system and its application to chemistry

This thesis outlines the design and construction of an amplified ultrashort pulse femtosecond laser system specifically for use as a tool for the analysis of chemical and biochemical systems. A summary of the problems associated with such a laser system and a stage by stage description of the design will be given along with a selection of experimental results aimed at emphasising the versatility of the system. Three separate experimental arrangements have been constructed for use with the laser system, all of which can be run at the same time: pump-probe transient absorption spectroscopy using a 400nm pump, and a white-light continuum probe, using 4% of the laser output, photon echo and transient grating spectroscopy, again using 4% of the laser output and ultrashort x-ray production using a novel liquid jet target for time-resolved x-ray diffraction, using 92% of the laser output. Pump-probe transient absorption studies have been carried out on zinc 5,10,15,20-tetracarboxyphenylporphyrin (Zn(TCPP)) sensitised TiO2 nanocrystalline films in an attempt to determine the rate of electron transfer between the Zn(TCPP) dye sensitiser and the TiO2 nanocrystalline film. Ultrashort x-ray production has been carried out using a liquid jet target of near-saturated aqueous copper nitrate or ethylene glycol. Through the use of a fast-flowing liquid target, the problem of precise movement of a solid target is removed. The commonly associated problems of debris production have also been successfully tackled and both the x-ray yield and output spectrum have been measured. Future experiments designed to measure x-ray diffraction from liquid water are also presented. (author)