Dissociation Dynamics of Superexcited Molecukes studied using the Advantage of Synchrotron Radiation for Continuous Wavelength, Linear Polarization, and Pulsed Time-Structure

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On the basis of the general understanding on the dynamic behavior of superexcited molecules, which was demonstrated by the present investigator for the first time in radiation chemistry and further carified by our previous dissociation studies using a low energy electron beam and a vuv-synchrotoron radiation, the present investigation has been proposed to perform detailed studies on the electronic property of superexcited states and their sissociation dynamics by advancing the synchrotron radiation (SR) for linear polarization and pulsed time-structure in combination with its continuous wavelength character.In the term of investigation, 1991-1993, we have carried out the following studies in accordance with our proposal.(1) Measurements of the angular momentum population of excited H atoms produced in the neutral-photodissociation of H_2 via superexcited state have been made by establishing a fast-response delayd coincidence method for time-resolved fluorescence measurement. Higher res … More olution measurements have also been performed in order to obtain further more state resolved information. The measurements have also been made for D_2 moleculars. We have also obtained the information on the symmetry of the superexcited H_2 by measuring the fluorescence intensity from excited H fragments relative to linear polarization vector of synchrotron radiation.(2) Absolute cross sections for photoabsorption, photoionization, and neutral photodissociation of polyatomic molecules, such as CH_4, CCl_4, SiF_4, and SiCl_4 have been measured to obtain the detailed information on partitioning of given photon energy into these processes.(3) vuv-fluorescence from neutral fragments produced in the dissociation of superexcited O_2, N_2, and N_2O has been observed and measured as a function of SR wavelength. The fluorescence has further been dispersed and measured as two dimensional fluorescence excitation spectra, which are the excitation function of both synchrotron radiation wavelength and fluorescence wavelength. Thease excitation spectra have given the detailed information on the potential structures of superexcited states, through which neutral dissociation proceeds. Less