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Title: Electron-stimulated reactions in nanoscale water films adsorbed on α-Al 2 O 3 (0001)

The radiation-induced decomposition and desorption of nanoscale amorphous solid water (D 2O) films adsorbed on an α-Al 2O 3(0001) surface was studied at low temperature in ultrahigh vacuum using temperature programmed desorption (TPD) and electron stimulated desorption (ESD) with a mono-energetic, low energy electron source. ESD yields of molecular products (D 2, O 2 and D 2O) and the total sputtering yield increased with increasing D 2O coverage up to ~15 water monolayers (i.e. ~15 x 10 15 cm -2) to a coverage-independent level for thicker water films. Experiments with isotopically-layered water films (D 2O and H 2O) demonstrated that the highest water decomposition yields occurred at the interfaces of the nanoscale water films with the alumina substrate and vacuum. However, the increased reactivity of the water/alumina interface is relatively small compared to the enhancements in the non-thermal reactions previously observed at the water/Pt(111) and water/TiO 2(110) interfaces. Here, we propose that the relatively low activity of Al 2O 3(0001) for the radiation-induced production of molecular hydrogen is associated with lower reactivity of this surface with hydrogen atoms, which are likely precursors for the formation of molecular hydrogen.
Authors:
 [1] ;  [1]
  1. Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Physical Sciences Division
Publication Date:
Report Number(s):
PNNL-SA-132648
Journal ID: ISSN 1463-9076; TRN: US1802372
Grant/Contract Number:
AC05-76RL01830
Type:
Accepted Manuscript
Journal Name:
Physical Chemistry Chemical Physics. PCCP (Print)
Additional Journal Information:
Journal Name: Physical Chemistry Chemical Physics. PCCP (Print); Journal Volume: 20; Journal Issue: 17; Journal ID: ISSN 1463-9076
Publisher:
Royal Society of Chemistry
Research Org:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Energy Frontier Research Centers (EFRC) (United States). Interfacial Dynamics in Radioactive Environments and Materials (IDREAM)
Sponsoring Org:
USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; 08 HYDROGEN; water; alumina; non-thermal chemistry; nuclear waste; hydrogen; electron-stimulated desorption
OSTI Identifier:
1432718

Petrik, Nikolay G., and Kimmel, Greg A.. Electron-stimulated reactions in nanoscale water films adsorbed on α-Al 2 O 3 (0001). United States: N. p., Web. doi:10.1039/c8cp01284a.
Petrik, Nikolay G., & Kimmel, Greg A.. Electron-stimulated reactions in nanoscale water films adsorbed on α-Al 2 O 3 (0001). United States. doi:10.1039/c8cp01284a.
Petrik, Nikolay G., and Kimmel, Greg A.. 2018. "Electron-stimulated reactions in nanoscale water films adsorbed on α-Al 2 O 3 (0001)". United States. doi:10.1039/c8cp01284a.
@article{osti_1432718,
title = {Electron-stimulated reactions in nanoscale water films adsorbed on α-Al 2 O 3 (0001)},
author = {Petrik, Nikolay G. and Kimmel, Greg A.},
abstractNote = {The radiation-induced decomposition and desorption of nanoscale amorphous solid water (D2O) films adsorbed on an α-Al2O3(0001) surface was studied at low temperature in ultrahigh vacuum using temperature programmed desorption (TPD) and electron stimulated desorption (ESD) with a mono-energetic, low energy electron source. ESD yields of molecular products (D2, O2 and D2O) and the total sputtering yield increased with increasing D2O coverage up to ~15 water monolayers (i.e. ~15 x 1015 cm-2) to a coverage-independent level for thicker water films. Experiments with isotopically-layered water films (D2O and H2O) demonstrated that the highest water decomposition yields occurred at the interfaces of the nanoscale water films with the alumina substrate and vacuum. However, the increased reactivity of the water/alumina interface is relatively small compared to the enhancements in the non-thermal reactions previously observed at the water/Pt(111) and water/TiO2(110) interfaces. Here, we propose that the relatively low activity of Al2O3(0001) for the radiation-induced production of molecular hydrogen is associated with lower reactivity of this surface with hydrogen atoms, which are likely precursors for the formation of molecular hydrogen.},
doi = {10.1039/c8cp01284a},
journal = {Physical Chemistry Chemical Physics. PCCP (Print)},
number = 17,
volume = 20,
place = {United States},
year = {2018},
month = {4}
}