Photoemission and electron-energy-loss spectroscopy investigation of CO
Photoemission and electron-energy-loss spectroscopy investigation of CO
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CO 的光电发射和电子能量损失光谱研究
DOI：
10.1103/physrevb.32.6222
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发表时间：
1985
期刊：
影响因子：
--
通讯作者：
de Paola Ra
中科院分区：
文献类型：
--
作者：
D. Heskett;I. StrathyI;Plummer Ew;de Paola Ra
本文采用低能电子衍射、角分辨同步辐射紫外光电子能谱（UPS）、角积分UPS和X射线光电子能谱、电子能量损失谱（EELS）、热脱附谱和功函数测量等技术，研究了钾预覆盖量为Θ K ≥ 0.3时CO+ K/Cu（100）体系的电子结构。我们的UPS结果表明，在K存在下，CO分子的对称性降低，CO的5σ和1π能级的强烈分裂和杂化，σ共振的位置没有实质性的移动，CO卫星峰的强度显著降低，在促进体系中的E-F增强，在不同的K和CO覆盖度下，K 3 p核心能级发生了显著变化。EELS表明，在Cu（100）上存在K时，在共吸附体系中，CO伸缩频率从2070 cm-1移动到1530 cm-1。功函数的结果是类似的变化，在其他共吸附系统与高碱金属precoverages。我们的多探针的结果是最好的解释CO分子结合到干净的表面主要通过σ键。K原子的局部存在导致成键主要为类π键，包括电荷转移到CO 2π轨道和显著的1π-K直接相互作用。
We have investigated the system CO+ K/Cu (100) at a potassium precoverage of Θ K∼ 0.3 using the techniques of low-energy electron diffraction, angle-resolved ultraviolet photoemission spectroscopy (UPS) with a synchrotron radiation source, angle-integrated UPS and x-ray photoemission spectroscopy, electron-energy-loss spectroscopy (EELS), thermal desorption spectroscopy, and work-function measurements. Our UPS results demonstrate a reduction in symmetry of the CO molecules in the presence of K, a strong splitting and hybridization of the CO 5σ and 1π levels, lack of a substantial shift in the position of the σ resonance, a dramatic reduction in the intensity of CO satellite peaks, enhancement at E F in the promoted system, and significant changes in the K 3p core levels at different coverages of K and CO. EELS demonstrates a dramatically weakened C—O bond in the presence of K on Cu (100), with a shift in the CO stretching frequency from 2070 to 1530 cm− 1 in the coadsorbed system. The work-function results are similar to changes reported in other coadsorbed systems with high alkali-metal precoverages. Our multiprobe results are best explained by a CO molecule bound to the clean surface primarily through a σ bond. The local presence of a K atom causes the bonding to become predominately π-like, involving both charge transfer into the CO 2π orbital and significant 1π-K direct interaction.