Development of High-Resolution Laboratory Rapid EXAFS Apparatus Using an Imaging Plate Detector

点击翻译按钮获取中文摘要

The detection of key species in dynamic reaction processes, in which the species change and react in every moment, is quite important for analysis in the molecular level. Because the detection and the evaluation of the dynamic behavior of reaction intermediates and short-lived species are the key points for the analysis in dynamic reaction systems, we have performed the following investigations in this work.1.Development of Stopped-Flow Laboratory EXAFS Apparatus Using an Imaging Plate DetectorThe stopped-flow laboratory EXAFS apparatus consists of a goniometer with a thin plate Ge (111) crystal as a polychromator in the dispersive mode, a fast imaging plate detector, and a stopped-flow sample-mixing apparatus. The imaging plate is rolled around a rotating dram and is exposed to transmitted X-rays through a sample cell in the stopped-flow assembly.2.Development of Time-Resolved Stopped-Flow EXAFS System Using Synchrotron RadiationOn the basis of knowledges obtained in the development o … More f the laboratory EXAFS apparatus, the time resolved stopped-flow EXAFS system using synchrotron radiation has been developed at the BL-12C station of the Photon Factory of the National Laboratory for High Energy Physics. The system consists of ionization chambers as an X-ray detector, fast current amplifiers, the stopped-flow sample-mixing apparatus modified to fit BL-12C,and a fast A/D converter used for the time-resolved mesurement in the step-scanning method. The minimum time-resolution was on the order of 1 ms due to the drift velocity of ions in the ionization chamber, and the dead time was 3.6 ms for the used stopped-flow assembly.3.Application to Dynamic Analysis for Some Fast Reaction SystemsThe structural determination has been performed for the reaction intermediates in the following reaction systems by using two newly developed time-resolved EXAFS apparatus, and then the reaction mechanisms have been evaluated.(1) Redox reaction between [Fe (CN) _6] ^<3-> and _L-ascorbic acid(2) Redox reaction between Fe^<2+> and [Co (NH_3) _5Cl] ^<2+> in N,N-dimethylformamide(3) Metalloporphyrin formation of 5,10,15,20-tetraphenylporphyrin in acetonitrile Less