期刊
APPLIED SURFACE SCIENCE
卷 530, 期 -, 页码 -出版社
ELSEVIER
DOI: 10.1016/j.apsusc.2020.147257
关键词
Adenine; Cerium oxide; Photoelectron spectroscopy; Resonant photoelectron spectroscopy; X-ray absorption spectroscopy; Density functional theory
类别
资金
- CERIC-ERIC consortium
- Czech Ministry of Education [LM2018116]
- U.S. National Science Foundation [CHE-1664984]
- Office of Science of US-DOE [DE-AC02-05CH11231]
- U.S. National Science Foundation Research Experience for Undergraduates Grant at LSU [EEC-1560305]
The adsorption of adenine on the CeO2(1 1 1)/Cu(1 1 1) surface in vacuum was studied by photoelectron spectroscopy, resonant photoelectron spectroscopy and near-edge X-ray absorption fine structure spectroscopy, and the present work describes in detail the bonding of the molecule to the ordered stoichiometric cerium dioxide film. The experimental findings were supported by density functional theory (DFT + U) analysis of different adsorption geometries of adenine on CeO2(1 1 1). The phase with adenine lying flat on the surface dominates on CeO2(1 1 1) up to 0.1 monolayer (ML) of adenine coverage. The mobility of single molecules was apparently sufficiently high to allow diffusion and formation of chain structures, which were observed to be stable in the temperature range from 25 to 250 degrees C. Beyond 0.1 ML, adenine molecules adsorb predominantly in an upright orientation. This phase, stable up to 120 degrees C, is according to theory stabilised via N3/Ce4+ and N9H/O2-. It was further complemented by experimental findings demonstrating free N10H(2) groups in adsorbed molecules. Thus, the saturation coverage of adenine on CeO2(1 1 1), 0.23 ML, is most likely characterised by a combination of parallel and upright bound molecules.
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