Femtosecond quantum beam pulse radiolysis

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For the purpose of investigating ultra fast chemical reactions in a subpico- or picosecond regime, we constructed a new pump and probe system and performed the experiment. The new pump and probe system consists of a 100 fs 0.3TW laser with passive mode-locked laser oscillator, a laser photocathode rf-gun which can generate a low emittance electron beam. Before the pump and probe experiment, the performance of the system such as a pulse duration of the laser, that of the third higher harmonies, that of white light, energy of the laser, the stability of the system and timing jitters of each components were investigated. Simultaneously the diagnostics skins to measure the timing jitter had been improved. In the pump and probe experiment, chemical reactions of transient species in a water was studied. As a sample, millipore water and 1M HClO4 in the 1.8 cmィイD1tィエD1 cell were selected and the decay of concentrations of eaq- and proton were measured. The reaction of eaq-with proton could be also observed.We performed time-resolved X-ray diffraction experiment, which is also a kind of pump and prove analysis. The laser pulse excites the lattice vibration of the target (pump) and picosecond laser plasma X-ray (LPX) is diffracted by the target (probe). As the preliminary experiment, the static diffraction images were obtained first. Picosecond LPX was produced using 50 fs 12 TW laser and the diffraction images of Ge, GaAs and Si were obtained.