Fluorescence yield absorption spectroscopy (PFY): After the X-photon strikes out an electron in the inner shell, a valence orbital electron returns to the inner shell cavity, and at the same time release another X-photon (with a slightly lower energy), which is the fluorescent photon. The yield of fluorescence for soft X-rays is about 1%. Advantage: low element-content samples, more bulk phase information of the sample.
Schematic diagram of fluorescence yield absorption spectroscopy
Soft X-ray fluorescence absorption spectra are collected in PFY mode. The PFY measurement system consists of an SDD, a data acquisition electronics device (PX5), an in-vacuum adjustable stand, vacuum leads, and vacuum connection flanges. The internal configuration of the chamber is shown in the right figure, with the incident soft X-rays at an angle of about 45 degree to the sample. The sample is also at about 45 degree to the SDD probe.
Reactivity regulation of lithium-rich oxide cathode materials
Lithium-rich manganese-based layer-like oxide cathode materials have attracted much attention due to advantages such as high specific capacity. In this study, a three-in-one lithium-rich oxide material modification strategy is proposed, which integrates LiSnO3 capping, Sn doping and spinel heterostructure. This strategy can significantly improve the oxygen ion redox activity and reversibility and reduce the irreversible release of oxygen. Meanwhile, the Coulombic efficiency, specific capacity, multiplicity characteristics and cyclability are all greatly improved. The O-K edge XAS in fluorescence mode demonstrated that the materials containing oxygen vacancies and spinel structure enhanced the reversibility of anion redox. This study is an important guide for improving the electrochemical performance of anode materials。[Adv. Funct. Mater. 2019, 1806706]
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