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本文用真空热蒸镀的方法得到了表面处有微量氧污染的有序表面合金,并用AES,LEED和HREELS研究了CO在该合金表面上的吸附。合金在52,75和105meV处产生三个振动峰,它们分别对应于表面上和表面Al原子以下的Al和氧原子之间的伸缩振动,在室温和低温下(135K),CO分子直立吸附在合金表面Ni原子顶位和最近邻的两个Ni原子桥位上并在250meV 和222meV处产生相应的损失峰。CO暴露量太子2.0L以后,105meV的损失峰强度随CO暴露量的增加有明显的增加,这是由于吸附在表面的CO有部分分解,分解后的氧原子和Al原子结合优先占据表面以下的位置,CO的分解速率与氧污染的多少有关,氧原子越多,分解速率越快。据我们所知,这是第一次在室温下观察到在Ni-Al合金表面上CO的分解。
In this paper, an ordered surface alloy with micro-oxygen contamination on the surface was obtained by vacuum thermal evaporation. The adsorption of CO on the surface of the alloy was studied by AES, LEED and HREELS. The alloy produces three vibrational peaks at 52,75 and 105meV, which correspond to the stretching vibration between Al and oxygen atoms below the surface and surface Al atoms, respectively. At room temperature and low temperature (135K), the CO molecules adsorbed upright The Ni atoms at the top and the nearest neighbors of the Ni atom on the alloy surface are bridged and produce corresponding loss peaks at 250 meV and 222 meV. After 2.0L of CO exposure, the peak intensity of 105meV loss significantly increased with the increase of CO exposure, which is due to the partial decomposition of CO adsorbed on the surface, the decomposition of oxygen atoms and Al atoms preferentially occupy the surface below the surface Location, CO decomposition rate and how much oxygen pollution, the more oxygen atoms, the decomposition rate faster. To our knowledge, this is the first time that decomposition of CO on the surface of Ni-Al alloys has been observed at room temperature.