Huang Weixin, Wei Wei, Zhao Wei, White J M
Department of Chemical Physics, University of Science and Technology of China, Hefei 230026, China.
J Phys Chem B. 2006 Mar 23;110(11):5547-52. doi: 10.1021/jp0541922.
The characteristics of 1,3-butadiene (C(4)H(6)) adsorbed on Cu(111) were investigated with temperature-programmed desorption (TPD) and two-photon photoemission spectroscopy (2PPE). Dosed at 90 K, the work function drops by 0.4 eV and TPD provides no evidence for dissociation, but there are four coverage-dependent local maxima located at 195, 135, 121, and 115 K. From the 2PPE spectra, three unoccupied electronic states of the C(4)H(6)-Cu(111) system were identified: the LUMO (pi(1), 2a(u)), LUMO + 1 (pi(2), 2b(g)), and LUMO + 2 (sigma*, 7b(u)), lying 1.3, 3.4, and 4.8 eV above the Fermi level, respectively. Although the excitation mechanisms for the LUMO and LUMO + 1 are substrate mediated, the excitation of the LUMO + 2 is attributed to intramolecular excitation.
采用程序升温脱附（TPD）和双光子光电子能谱（2PPE）研究了吸附在Cu(111)上的1,3 - 丁二烯（C₄H₆）的特性。在90 K下进行剂量注入时，功函数下降了0.4 eV，TPD没有提供解离的证据，但有四个与覆盖度相关的局部最大值，分别位于195、135、121和115 K。从2PPE光谱中，确定了C₄H₆ - Cu(111)体系的三个未占据电子态：最低未占分子轨道（LUMO，π₁*，2aᵤ）、LUMO + 1（π₂*，2b₉）和LUMO + 2（σ*，7bᵤ），分别位于费米能级上方1.3、3.4和4.8 eV处。虽然LUMO和LUMO + 1的激发机制是由衬底介导的，但LUMO + 2的激发归因于分子内激发。
