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用高分辨率电子能量损失谱研究了O_2和CO在有序合金表面Pd{θ01}c(2×2)-Ma上的共吸附.室温下,当CO的暴露量为1.0L(朗缪尔Langmuir)时,能量损失谱中位于253mcV的峰是由吸附于第一层中Pd原子顶位的CO的C—O伸缩振动引起的.继续暴露θ.1L的O_1之后,上述253meV峰的强度大大减弱.低温140K时,O_2和CO在Pd{001}C(2×2)-Mn上共吸附后测得的能量损失谱中出现了一个损失能量为285meV的新峰.在相同的CO的暴露量下,该峰的强度随预吸附的氧量的增加而增加.样品升温至300K停留1min,285meV的峰消失.分析表明,该峰是由垂直吸附于表面的CO_2引起的.在上述有序合金表面生成CO_2的微观过程可以解释为离解吸附于第一层中两个Mn原子和两个Pd原子间中心位上的氧原子与吸附于其近邻Pd原子顶位上的CO分子之间的相互作用.
The co-adsorption of O_2 and CO on the Pd {θ01} c (2 × 2) -Ma surface was investigated by high-resolution electron energy loss spectroscopy. When CO exposure was 1.0L (Langmuir Langmuir), the peak at 253 mcV in the energy loss spectrum is caused by the C-O stretching vibration of the CO adsorbed on the top site of the Pd atom in the first layer. The intensity of the above 253 meV peak was greatly increased after continued exposure of O.1 at 0.1 L And a new peak with an energy loss of 285meV appeared in the energy loss spectra of O_2 and CO adsorbed on Pd {001} C (2 × 2) -Mn at low temperature of 140 K. At the same CO exposure The peak intensity increased with the increase of preadsorbed oxygen.The samples were heated to 300 ℃ for 1min and the peak of 285meV disappeared.The results showed that the peak was caused by the vertical adsorption of CO_2 on the surface.In the above order The microscopic process of CO 2 generation on the alloy surface can be explained as the mutual dissociation between the oxygen atoms which are dissociated and adsorbed on the center of two Mn atoms and two Pd atoms in the first layer and the CO molecules adsorbed on the top of Pd atom adjacent to it effect.