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#H2o xps peak full#

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).

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.

#H2o xps peak full#

As for the H 2O-exposed surface, the saturated band bending depends on the H 2O supply rate: When the supply rate is high, half dissociation of H 2O is dominant and the band bending approaches the flat-band condition due to the termination of surface Ga dangling bonds by H and OH when the supply rate is low, the saturated band bending matches that of the O 2-adsorbed surface, presumably due to the O atoms that are formed by full dissociation of H 2O.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). In the case of the O 2-exposed surface, upward band bending is observed above the effective coverage of 3/4 ML (3/8 ML of O atoms) because the Fermi level becomes pinned to the N-2p-originated surface states, which is formed through Ga–N bond scission by O atom adsorption and insertion into the slab. Overall, the AP-XPS results are in good agreement with the predictions, and we discuss the possible origin of the difference in the band bending of H 2O- and O 2-adsorbed surfaces. In this study, the evolution of the n-GaN(0001) surface geometric structure and the corresponding band bending (a key parameter that describes the surface electronic structure of a semiconductor) during H 2O and O 2 exposure is predicted from first-principles calculations and confirmed by ambient pressure X-ray photoemission spectroscopy (AP-XPS) measurements. GaN is an excellent candidate for photocatalytic, optoelectronic, and high-power devices, and the interaction between the GaN surface and ambient species, especially H 2O and O 2, has drawn exceptional attention.