No abstract

No abstract

A local atomic structure analysis of the interface between chemical vapor-deposited SiO2 and 4H-SiC was achieved via a combination of chemical-state-selective X-ray absorption spectroscopy and the use of a sample with a very thin oxide film. The Si K-edge spectrum, which monitors the SiC-assigned Auger peak, allows the SiC side of the SiO2/SiC interface to be selectively measured through the SiO2 film. We estimate the coordination number of the first nearest neighbor to be reduced by 17% with respect to the SiC bulk. This suggests that C vacancy defects exist at the SiC side of the interface.

The absorption spectra of the HCl, NaCl, and NaOH solutions during and after the solution plasma sputtering for the preparation of gold nanoparticles are measured by in situ ultraviolet-visible (UV-vis) spectroscopy to determine the particle diameter and behavior. In the solution plasma sputtering, gold particles are directly formed from the plasma phase and not by the reduction of Au 3+ ions dissolved from electrodes. The initial diameter and behavior differ according to the solution used. In HCl solution, gold nanoparticles are formed and dissolve into Au 3+ ions. When the solution is saturated, the gold nanoparticles grow by the aggregation of Au 3+ ions. Cluster-sized particles are formed in NaCl solution that constitute nanoparticles, which are very stable for several days. Gold nanoparticles of 3 nm diameter are formed in NaOH solution, which aggregate over several days. The contribution of chlorine ions to the day-order stability of gold nanoparticles is suggested.

At the beamline BL6N1 of Aichi Synchrotron Radiation Center (AichiSR), X-ray absorption and X-ray photoemission spectroscopies with the photon energy range of 1.75 -6 keV can be carried out. In 2018, the former double-crystal monochromator has been replaced to a new one equipped with a cooling system for monochromator crystals. As a consequence, the stability of X-ray beam in terms of photon energy and intensity has been improved significantly. Taking this opportunity, the latest details of the experimental instruments of BL6N1 and the examples of the X-ray absorption and photoemission spectroscopy experiments available at BL6N1 will be presented in this article.