Dissociation-Recombination Dynamics of Iodine Molecule in Super Fluid State Helium

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In this research project we planned to observe some chemical reactions in the super-fluid helium as a solvent and to build up a measurement system for this purpose. The experimental setup needed for this purpose is a femtosecond-picosecond laser system synchronized with a nanosecond laser system which excites just before the pump-probe experiment. We improved the experimental system which we built previously to realize this synchronization. Completed improvements are follows ; 1)The laser pulses from Regen amplifier system of which repetition rate is 1kHz are reduced to a single pulse of variable repetition by using of a shutter system driven by galvano motors.2) To enhance the probe wavelength in pump-probe experiment to near-IR region. We built a new multi-channel spectrograph system and realize a measurement in 1100-1700nm area. 3) To improve the accuracy of the pump-probe experiment, we built up a new system to detect a small deviation of probing light less than about 10^<-7>. T check and to improve the accuracy of these experimental systems, we performed coherent phonon (CP) spectroscopy and optical heterodyne detection of optical Kerr effect (OKE). In CP experiment, we succeeded to probe the relaxation process of lattice vibrations clearly and developed a new method to estimate amount of lattice defects quantitatively by using of ion-irradiation. In OKE experiment, we attempted to detect very small signal to discuss the relationship between the molecular orientational relaxation and inter-molecular interactions. These new experimental result was obtained because of the remarkable improvement of the experimental accuracy. In the next step, we planned to enter the liquid helium experiment.