Adsorption structure of adenine on cerium oxide
Adsorption structure of adenine on cerium oxide
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DOI：
10.1016/j.apsusc.2020.147257
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发表时间：
2020-11-15
影响因子：
6.7
通讯作者：
Tsud, Nataliya
中科院分区：
文献类型：
--
作者：
Bercha, Sofiia;Bhasker-Ranganath, Suman;Tsud, Nataliya
利用光电子能谱、共振光电子能谱和近边X射线吸收精细结构谱研究了腺嘌呤在CeO 2（111）/Cu（111）表面的真空吸附，详细描述了腺嘌呤分子与有序化学计量比的CeO 2薄膜的键合过程.实验结果得到支持的密度泛函理论（DFT + U）分析不同的吸附几何腺嘌呤CeO 2（1 1 1）。腺嘌呤平躺在表面上的相占主导地位的CeO 2（1 1 1）高达0.1单层（ML）的腺嘌呤覆盖。单分子的流动性显然足够高，以允许扩散和形成链结构，观察到其在25至250摄氏度的温度范围内稳定。超过0.1 ML，腺嘌呤分子主要以直立方向吸附。该相在高达120摄氏度下稳定，根据理论，通过N3/Ce 4+和N9 H/O2-稳定。实验结果进一步补充了吸附分子中的游离N10 H（2）基团。因此，腺嘌呤在CeO 2（111），0.23 ML上的饱和覆盖度最有可能以平行和直立结合分子的组合为特征。
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.