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Factors influencing surface carbon contamination in ambient-pressure x-ray photoelectron spectroscopy experiments
Journal of Vacuum Science & Technology A ( IF 2.9 ) Pub Date : 2021-05-20 , DOI: 10.1116/6.0001013 Nicolo’ Comini 1 , Thomas Huthwelker 2 , J. Trey Diulus 1 , Jürg Osterwalder 1 , Zbynek Novotny 1, 2
Journal of Vacuum Science & Technology A ( IF 2.9 ) Pub Date : 2021-05-20 , DOI: 10.1116/6.0001013 Nicolo’ Comini 1 , Thomas Huthwelker 2 , J. Trey Diulus 1 , Jürg Osterwalder 1 , Zbynek Novotny 1, 2
Affiliation
Carbon contamination is a notorious issue that has an enormous influence on surface science experiments, especially in near-atmospheric conditions. While it is often mentioned in publications when affecting an experiment’s results, it is more rarely analyzed in detail. We performed ambient-pressure x-ray photoelectron spectroscopy experiments toward examining the build-up of adventitious carbon species (both inorganic and hydrocarbons) on a clean and well-prepared surface using large-scale (50 × 10 mm2) rutile TiO2(110) single crystals exposed to water vapor and liquid water. Our results highlight how various factors and environmental conditions, such as beam illumination, residual gas pressure and composition, and interaction with liquid water, could play roles in the build-up of carbon on the surface. It became evident that beam-induced effects locally increase the amount of carbon in the irradiated area. Starting conditions that are independent of light irradiation determine the initial overall contamination level. Surprisingly, the rate of beam-induced carbon build-up does not vary significantly for different starting experimental conditions. The introduction of molecular oxygen in the order of 10 mbar allows for fast surface cleaning during x-ray illumination. The surface carbon contamination can be completely removed when the oxygen partial pressure is comparable to the partial pressure of water vapor in the millibar pressure range, as was tested by exposing the TiO2(110) surface to 15 mbar of water vapor and 15 mbar of molecular O2 simultaneously. Furthermore, our data support the hypothesis that the progressive removal of carbon species from the chamber walls by competitive adsorption of water molecules takes place following repeated exposure to water vapor. We believe that our findings will be useful for future studies of liquid-solid interfaces using tender x rays, where carbon contamination plays a significant role.
中文翻译:
环境压力 X 射线光电子能谱实验中影响表面碳污染的因素
碳污染是一个臭名昭著的问题,它对表面科学实验有着巨大的影响,尤其是在接近大气条件下。虽然在影响实验结果的出版物中经常提到它,但很少对其进行详细分析。我们进行了环境压力 X 射线光电子能谱实验,以使用大规模 (50 × 10 mm 2 ) 金红石型 TiO 2在干净且准备充分的表面上检查外来碳物质(无机和碳氢化合物)的积累(110) 暴露于水蒸气和液态水的单晶。我们的结果强调了各种因素和环境条件,如光束照明、残余气体压力和成分以及与液态水的相互作用,如何在表面碳的积聚中发挥作用。很明显,光束引起的效应会局部增加照射区域中的碳量。与光照射无关的启动条件决定了初始的总体污染水平。令人惊讶的是,对于不同的起始实验条件,束诱导碳堆积的速率没有显着变化。10 毫巴量级的分子氧的引入允许在 X 射线照射期间快速清洁表面。2 (110) 表面同时承受 15 毫巴的水蒸气和 15 毫巴的分子 O 2。此外,我们的数据支持这样的假设,即在反复暴露于水蒸气后,通过水分子的竞争吸附逐渐从室壁去除碳物质。我们相信,我们的发现将有助于未来使用嫩 x 射线研究液固界面,其中碳污染起着重要作用。
更新日期:2021-07-02
中文翻译:
环境压力 X 射线光电子能谱实验中影响表面碳污染的因素
碳污染是一个臭名昭著的问题,它对表面科学实验有着巨大的影响,尤其是在接近大气条件下。虽然在影响实验结果的出版物中经常提到它,但很少对其进行详细分析。我们进行了环境压力 X 射线光电子能谱实验,以使用大规模 (50 × 10 mm 2 ) 金红石型 TiO 2在干净且准备充分的表面上检查外来碳物质(无机和碳氢化合物)的积累(110) 暴露于水蒸气和液态水的单晶。我们的结果强调了各种因素和环境条件,如光束照明、残余气体压力和成分以及与液态水的相互作用,如何在表面碳的积聚中发挥作用。很明显,光束引起的效应会局部增加照射区域中的碳量。与光照射无关的启动条件决定了初始的总体污染水平。令人惊讶的是,对于不同的起始实验条件,束诱导碳堆积的速率没有显着变化。10 毫巴量级的分子氧的引入允许在 X 射线照射期间快速清洁表面。2 (110) 表面同时承受 15 毫巴的水蒸气和 15 毫巴的分子 O 2。此外,我们的数据支持这样的假设,即在反复暴露于水蒸气后,通过水分子的竞争吸附逐渐从室壁去除碳物质。我们相信,我们的发现将有助于未来使用嫩 x 射线研究液固界面,其中碳污染起着重要作用。