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用原子交叠和电子离域-分子轨道(ASED-MO)方法和原子集团模型Pt_(21)O_2研究了O_2与Pt(111)面的相互作用过程。由总能极小,发现O_2在Pt(111)面平躺吸附比垂直吸附能量更低,其中O_2平行吸附于桥位是最稳定的吸附位,而且O_2分子键长伸长到1.35A,与最近的近边X射线吸收精细结构谱(NEXAFS)实验值(1.37±0.05)A符合得很好。同时,衬底向O_2分子转移的电荷大约为0.6e,它们主要填充于O_2分子的1π_g反键轨道。平躺吸附的O_2分子在解离过程中存在约0.20eV的势垒,解离的O原子将占据能量最低的三度空位(hcp),Pt-O键长为1.95A。另外,还通过局域态密度计算对UPS谱峰的组分及起源作了详细分析,并对O_2在Pt(111)面的物理吸附作了一些半定量的讨论。
The interaction between O_2 and Pt (111) surface was investigated by atomic overlap and electron delocalization - molecular orbital (ASED-MO) method and atomic group model Pt_ (21) O_2. From the smallest total energy, it was found that the horizontal adsorption of O_2 on Pt (111) plane was lower than that on the vertical adsorption side. O_2 adsorbed parallel to the bridge site was the most stable adsorption site, and the molecular length of O_2 was 1.35A. The recent near-edge X-ray absorption fine structure spectrum (NEXAFS) experimental value (1.37 ± 0.05) A is in good agreement. At the same time, the charges transferred to the O 2 molecules are about 0.6e, which mainly fill the 1π_g antibonding orbital of O 2 molecules. O 2 molecules lying in the horizontal direction have a potential barrier of about 0.20 eV during dissociation, and the dissociated O atoms occupy the third lowest energy (hcp) with a Pt-O bond length of 1.95A. In addition, the composition and origin of the UPS peak are also analyzed in detail by means of the calculation of the local density of states, and some semi-quantitative discussions are made on the physical adsorption of O_2 on the Pt (111) surface.