Development of high resolution TRAXS and its applications to surface science

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The aim of this project is to improve a "RHEED-TRAXS" method, our original technique for surface analysis, and to develop a "high resolution TRAXS". The achievements in this project term are as follows;1. For the high resolution RHEED-TRAXS (reflection-high-energy electron diffraction--total-reflection-angle-X-ray spectroscopy), we developed an X-ray spectrometer which consisted of a crystal spectrometer and a position-sensitive X-ray detector. Combining it with our RHEED-MBE(molecular beam epitaxy) apparatus, we obtained high-resolution X-ray energy spectra which had intensities enough for observations of dynamical processes with short data-aquisition time.2. Using a flat LiF(200) crystals as a spectrometer, we confirmed an energy resolution of about 13eV at GaK lines (9.2keV), which was about ten times higher than that (150eV) of the previous TRAXS method. Then, we expect to carry out EXAFS (extended X-ray absorption fine structures) with this high energy resolution.3. With use of a Si surface, of which atomic structures and chemical compositions were well characterized with this new technique, we measured the surface conductance, and found it to be sensitively influenced by the atomic-scale structures of the surface. The changes in atomic arrangements on the surface lead to changes of surface electronic states and space-charge layer, resulting in changes in the macroscopic electrical properties such as surface conductance. This findings will be important not only from the fundamental interests, but also from their devise applications.