scholarly journals Revisiting heat treatment and surface activation of GaAs photocathodes: In situ studies using scanning tunneling microscopy and photoelectron spectroscopy

2020 ◽  
Vol 128 (4) ◽  
pp. 045308
Author(s):  
Jyoti Biswas ◽  
Jiajie Cen ◽  
Mengjia Gaowei ◽  
Omer Rahman ◽  
Wei Liu ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Scanning Tunneling Microscopy ◽  
Photoelectron Spectroscopy ◽  
Scanning Tunneling ◽  
Surface Activation ◽  
Tunneling Microscopy ◽  
In Situ Studies

scholarly journals Recent Progress with In Situ Characterization of Interfacial Structures under a Solid–Gas Atmosphere by HP-STM and AP-XPS

Materials ◽  
2019 ◽  
Vol 12 (22) ◽  
pp. 3674 ◽  
Author(s):  
Zhang ◽  
Sun ◽  
Shen ◽  
Hu ◽  
Hu ◽  
...  
Keyword(s):  
Scanning Tunneling Microscopy ◽  
Photoelectron Spectroscopy ◽  
Ambient Pressure ◽  
High Vacuum ◽  
Catalytic Reactions ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
X Ray ◽  
Heterogeneous Catalytic

: Surface science is an interdisciplinary field involving various subjects such as physics, chemistry, materials, biology and so on, and it plays an increasingly momentous role in both fundamental research and industrial applications. Despite the encouraging progress in characterizing surface/interface nanostructures with atomic and orbital precision under ultra-high-vacuum (UHV) conditions, investigating in situ reactions/processes occurring at the surface/interface under operando conditions becomes a crucial challenge in the field of surface catalysis and surface electrochemistry. Promoted by such pressing demands, high-pressure scanning tunneling microscopy (HP-STM) and ambient pressure X-ray photoelectron spectroscopy (AP-XPS), for example, have been designed to conduct measurements under operando conditions on the basis of conventional scanning tunneling microscopy (STM) and photoemission spectroscopy, which are proving to become powerful techniques to study various heterogeneous catalytic reactions on the surface. This report reviews the development of HP-STM and AP-XPS facilities and the application of HP-STM and AP-XPS on fine investigations of heterogeneous catalytic reactions via evolutions of both surface morphology and electronic structures, including dehydrogenation, CO oxidation on metal-based substrates, and so on. In the end, a perspective is also given regarding the combination of in situ X-ray photoelectron spectroscopy (XPS) and STM towards the identification of the structure–performance relationship.

scholarly journals In situ scanning tunneling microscopy study of Ca-modified rutile TiO2(110) in bulk water

2015 ◽  
Vol 6 ◽  
pp. 438-443 ◽  
Author(s):  
Giulia Serrano ◽  
Beatrice Bonanni ◽  
Tomasz Kosmala ◽  
Marco Di Giovannantonio ◽  
Ulrike Diebold ◽  
...  
Keyword(s):  
Scanning Tunneling Microscopy ◽  
Photoelectron Spectroscopy ◽  
Surface Segregation ◽  
Microscopy Study ◽  
Bulk Water ◽  
Scanning Tunneling ◽  
Aqueous Environment ◽  
Tunneling Microscopy ◽  
Stm Images

Despite the rising technological interest in the use of calcium-modified TiO2 surfaces in biomedical implants, the Ca/TiO2 interface has not been studied in an aqueous environment. This investigation is the first report on the use of in situ scanning tunneling microscopy (STM) to study calcium-modified rutile TiO2(110) surfaces immersed in high purity water. The TiO2 surface was prepared under ultrahigh vacuum (UHV) with repeated sputtering/annealing cycles. Low energy electron diffraction (LEED) analysis shows a pattern typical for the surface segregation of calcium, which is present as an impurity on the TiO2 bulk. In situ STM images of the surface in bulk water exhibit one-dimensional rows of segregated calcium regularly aligned with the [001] crystal direction. The in situ-characterized morphology and structure of this Ca-modified TiO2 surface are discussed and compared with UHV-STM results from the literature. Prolonged immersion (two days) in the liquid leads to degradation of the overlayer, resulting in a disordered surface. X-ray photoelectron spectroscopy, performed after immersion in water, confirms the presence of calcium.

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