The Department of Chemical Engineering welcomes Canadian Light Source’s Senior Staff Scientist Yongfeng Hu for a seminar about hard x-ray photoemission spectroscopy. All are welcome.
Photoemission spectroscopy (or XPS) has been used widely to study the electronic structure of valence and core levels. However, the conventional XPS is only surface sensitive. In order to probe the interface and bulk properties of materials, the hard X-ray photoemission spectroscopy (HXPES) has received an increasing interest in the last decade, due to the deep probing ability of photoelectron with higher kinetic energy (2-10 keV).
Recently, a HXPES system was developed at the Canadian Light Source, using the high energy version of a R4000 electron analyzer based spectrometer connected to a medium energy beamline, the Soft X-ray Microcharacterization Beamline (SXRMB). After an introduction to the HXPES, Yongfeng Hu will give examples demonstrating the controlled probing depth of HXPES at SXRMB by tuning the photon energy (2-9 keV) in the study of a series of SiO2/SiC multi-layer samples.
The electric charging effect makes the conventional XPS measurements of non-conducting samples challenging. Taking advantage of the probing ability of the HXPES, the electronic structure of insulating SiO2 glass can be studied by depositing a thin layer of Cr metal. Yongfeng will show examples of application of HXPES on the study of interface and bulk properties (eg, SEI layers) of battery materials. Finally, he will discuss the development of the in-situ study of energy materials by HXPES.
Combined with the high resolution X-ray absorption spectroscopy available at the SXRMB, the HXPES offers a powerful non-destructive technique in applications on Li ion battery, fuel cell and nano-catalysts.
Yongfeng Hu is a Senior Staff Scientist at the Canadian Light Source (CLS), which is a leading centre of excellence in synchrotron science and its applications.
The CLS is a critical tool for Canadian research and development in sectors such as mining and energy, health and life sciences, and advanced manufacturing. Yongfeng’s research interests include synchrotron instrumentation and the application of synchrotron radiation techniques.
He has built and commissioned three beamlines (soft and hard x-rays) at the synchrotron facilities in US and Canada. He has also designed and built many endstations, including photoelectron and photoabsorption and others, for the application of synchrotron based technique.
He studies chemical and electronic structure and its interplay with material properties and spectroscopy, and is pushing for ‘real,’ in-situ measurement of energy, environmental and catalytic samples. He has published more than 260 peer-reviewed papers in areas of atomic and molecular chemistry and physics, material and environmental science, and synchrotron instrumentation.
Yongfeng’s areas of expertise include:
- Synchrotron radiation and beamlines
- Instrumentation in spectroscopy
- Solid state and surface chemistry
- Photoelectron and photoabsorption spectroscopy
- Material and environmental science
- Atomic and molecular spectroscopy
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