Fakultät für Physik und Zentrum für Nanointegration (CENIDE), Universität Duisburg-Essen, Lotharstr. 1, 47048 Duisburg, Germany.
J Phys Condens Matter. 2014 Sep 3;26(35):352001. doi: 10.1088/0953-8984/26/35/352001. Epub 2014 Aug 12.
The electron-phonon coupling parameters in the vicinity of the Γ point, λ(Γ), for electronic quantum well states in epitaxial lead films on a Si(1 1 1) substrate are measured using 5, 7 and 12 ML films and femtosecond laser photoemission spectroscopy. The λ (Γ) values in the range of 0.6-0.9 were obtained by temperature-dependent line width analysis of occupied quantum well states and found to be considerably smaller than the momentum averaged electron-phonon coupling at the Fermi level of bulk lead, (λ = 1.1-1.7). The results are compared to density functional theory calculations of the lead films with and without interfacial stress. It is shown that the discrepancy can not be explained by means of confinement effects or simple structural modifications of the Pb films and, thus, is attributed to the influence of the substrate on the Pb electronic and vibrational structures.
利用飞秒激光光电子发射谱，测量了外延在 Si(111)衬底上的 Pb 薄膜中电子量子阱态在 Γ 点附近的电子-声子耦合参数λ(Γ)。通过占据量子阱态的温度相关线宽分析，得到了 5、7 和 12 ML 薄膜的 0.6-0.9 范围内的 λ(Γ)值，发现其明显小于体 Pb 的费米能级处的平均动量电子-声子耦合值（λ=1.1-1.7）。将实验结果与有/无界面应力的 Pb 薄膜的密度泛函理论计算进行了比较。结果表明，这种差异不能用限制效应或 Pb 薄膜的简单结构修改来解释，因此归因于衬底对 Pb 电子和振动结构的影响。
