![si2p xps peak fitting si2p xps peak fitting](https://www.researchgate.net/profile/Shuyan-Yang-3/publication/269702299/figure/fig3/AS:294999221653509@1447344703546/The-XPS-fitting-peaks-of-model-compounds-a-O-1s-and-b-Si-2p-of-SiO-2-c-O-1s-and-d.png)
The studies indicate that the metallic As present at (111)B surface contributes strongly to the large surface recombination velocity found there, and to the inability of Na 2S to passivate the (111)B surface.
![si2p xps peak fitting si2p xps peak fitting](https://d12oja0ew7x0i8.cloudfront.net/images/Article_Images/ImageForArticle_4717(1).jpg)
The XPS results have been correlated with the results of previous photocorrosion and passivation studies conducted in a photoelectrochemical cell. The (111)B surface lacks this constituent, but shows significant amounts of metallic As. The (100) and (110) surfaces are relatively similar, with significant amounts of As-S species present at the interface. This last result has led us to examine n-GaAs as a function of crystallographic orientation after exposure to aqueous Na 2S containing solutions has been studied as a function of crystallographic orientation of the GaAs surface. The effect of coating the GaAs with a sulfide layer prior to immersion in the cell has also been explored. The dependence of GaAs more » photocorrosion on light intensity has been explored to better understand intrinsic differences between the lamplight studies and the picosecond photoluminescence studies. An important distinction between photocorrosion and photoetching of GaAs is elucidated by these studies. In our most extensive set of studies we conducted photo-illumination and XPS experiments to understand the chemistry occurring in the GaAs/methanol photoelectrochemical during photoexcitation. Studies of Corrosion, Passivation on n-GaAs(100)Methanol Photoelectrochemical Cell In these studies we have used picosecond photoluminescence and electrochemical studies to understand the GaAs/methanol interface. Since 1995 we have pursued a number of different studies that are quite diverse in nature but with the common theme of using novel laser based methods to study important processes at buried interfaces. Center for Functional Nanomaterials (CFN) Sponsoring Org.: USDOE Office of Science (SC), Basic Energy Sciences (BES) OSTI Identifier: 1614982 Alternate Identifier(s): OSTI ID: 1601515 Report Number(s): BNL-213845-2020-JAAM Journal ID: ISSN 0021-9606 TRN: US2104971 Grant/Contract Number: SC0012704 SC0014414 Resource Type: Journal Article: Accepted Manuscript Journal Name: Journal of Chemical Physics Additional Journal Information: Journal Volume: 152 Journal Issue: 8 Journal ID: ISSN 0021-9606 Publisher: American Institute of Physics (AIP) Country of Publication: United States Language: English Subject: 77 NANOSCIENCE AND NANOTECHNOLOGY Surface and interface chemistry 2D materials Chemical bonding Epitaxy Adsorption Ultra-high vacuum Density functional theory Silicates X-ray photoelectron = , Publication Date: Research Org.: Brookhaven National Lab. Center for Functional Nanomaterials (CFN) Yale Univ., New Haven, CT (United States).
![si2p xps peak fitting si2p xps peak fitting](https://www.researchgate.net/profile/Zied-Souguir/publication/229142830/figure/fig5/AS:667855116832782@1536240476501/The-fitted-high-resolution-C-1s-a-and-Si-2p-b-XPS-spectra-of-cellulose-after.png)
![si2p xps peak fitting si2p xps peak fitting](https://ars.els-cdn.com/content/image/1-s2.0-S2468217916300685-gr3.jpg)
The results reveal how the sensitivity of XPS to interfacial dipoles can be exploited to distinguish reactions taking place in confined spaces under 2D layers and how tuning the composition of the 2D layer can impact such reactions. Less water adsorption was observed at more » the aluminosilicate interface which is a consequence of Al strengthening the bond to the metal substrate. Although the stronger interaction between the bilayer and Pd substrate should restrict interfacial adsorption and reaction, similar trends were observed for water and hydrogen exposure to interfacial adsorbed oxygen. Incorporating Al into the 2D material caused the bilayer peaks to shift to lower binding energy which could be explained by electron donation from the metal to the bilayer. Spectra recorded under 0.5 Torr water revealed additional water adsorption and a further shift of the overlayer peaks to higher binding energy. Interfacial oxygen also reacted with H 2 to produce adsorbed water which also caused an upward binding energy shift of the SiO 2 peaks. These observations were attributed to the formation of a mixed water–hydroxyl interface, which eliminates the interfacial dipolar layer, and its associated electrostatic potential, created by adsorbed oxygen. Starting with oxygen adsorbed at the SiO2/Pd interface, exposure to water caused the SiO 2-derived XPS peaks to shift to higher binding energy and the removal of an O 1s feature associated with interfacial adsorbed oxygen. Ambient pressure x-ray photoelectron spectroscopy (AP-XPS) supported by density functional theory (DFT) calculations was used to characterize the interaction of water with two-dimensional (2D) silica and aluminosilicate bilayers on Pd(111).