分类： 核科学技术 >> 粒子加速器 提交时间： 2023-06-18 合作期刊: 《Nuclear Science and Techniques》
摘要： In order to do alignment between the timing signal and the synchrotron X-ray pulse on the sample spot in the time domain, measuring time structure of the storage ring on the sample spot inside the experimental hutch is a foundational step during the time-resolved experiments using the pulsed synchrotron X-rays with the time structure defined by the storage ring. In this work, the method of time-resolved X-ray excited optical luminescence (TRXEOL) was designed and implemented to do the measurement. It is based on the principle of time-correlated single photon counting techniques. The measurement system consists of a spectrometer with a detector of photomultiplier tube, a timing system, a set of nuclear instrument modules and a luminescent material of zinc oxide. The measurement was performed on the X-ray absorbed fine structure spectrum beamline at Shanghai Synchrotron Radiation Facility. The results show that this method can be used to measure the time structure of the storage ring with a precision of less than 1 ns. The measurement system can also be used for the time-resolved research for the optical luminescent materials.
分类： 物理学 >> 核物理学 提交时间： 2023-06-20
Zhang, Huan
Xie, Lei
Liang, Zhao-feng
Huang, Chao-qin
Wang, Hong-bing
Hu, Jin-ping
Jiang, Zheng
Song, Fei
摘要： Bimetallic catalysts typically exploitunique synergetic effects betweentwo metal species to achieve theircatalytic . Understanding the mechanism of CO oxidation using hybrid heterogeneous catalysts is important for effective catalyst design and environmental protection. Herein, we report a Bi-Au/SiO2tandem bimetallic catalyst forCO oxidation reactionoverthe Au/SiO2surface, which was monitoredusingnear-ambient-pressure X-ray photoelectron spectroscopy. The Au-decorated SiO2catalyst exhibited scarce activity in the CO oxidation reaction; However, the introduction of Bi to the Au/SiO2system promoted the catalytic activity. The mechanism is thought to involve the dissociationO2molecules in the presence of Bi, which results inspilloverofthe O species to adjacent Au atoms, thereby formingAu+. Further CO adsorption, followed by thermal treatment, facilitated theoxidation ofCO at the Au-Bi interface, resulting in a reversible reversion to the neutral Au valence state. Our work provides insightinto the mechanism of CO oxidation on tandem surfaces and will facilitatethe rational design of other Au-based catalysts
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