Time-resolved spectroscopy of photo-induced transitions and electronic excitations in quasi-1D metal wires on semiconductors

E5项目旨在从根本上理解半导体表面准一维金属线的非平衡性质，重点研究电子激发的超快动力学，包括未占据电子态的光谱和寿命，以及此类系统在光致相变过程中电子能带结构的瞬时变化。这些主题将以In/Si(111)、Pb/Si(557)和Au/Si(553)作为模型系统来讨论。位于杜伊斯堡和柏林的活动有着共同的科学目标，但使用了不同的实验方法：杜伊斯堡-埃森大学的团队专注于使用时间和角度分辨光电子发射(ARPES)和双光子光电子发射(2PPE)光谱学来研究布里渊区中心附近空置电子态的光谱学和动力学。柏林Fritz Haber研究所的研究小组开发了基于时间分辨XUV的ARPES，以研究整个布里渊区光致相变过程中的电子动力学和电子结构变化。在E3中进行的静态光学光谱(RAS)实验的基础上，后面的实验将得到高激光通量下的时间分辨光学光谱(SFG，RAS)的补充。我们项目中使用的超快技术研究了激发态电子动力学。在研究单位内，我们的活动与项目T1和T2一起形成，该项目在理论上处理CDW形成和光诱导相变时电子结构的变化，以及项目E7，该项目通过飞秒电子衍射分析互补的结构动力学，飞秒电子衍射是一维系统动力学的一个重点领域。

The project E5 aims at a fundamental understanding of the non-equilibrium properties of quasi-1D metal wires on semiconductor surfaces and focuses on the ultrafast dynamics of electronic excitations, including spectroscopy and lifetimes of unoccupied electronic states as well as on transient changes of the electronic band structure during photoinduced phase transitions in such systems. These topics will be addressed using In/Si(111), Pb/Si(557), and Au/Si(553) as model systems. The activities located in Duisburg and Berlin share joint scientific goals, but use different experimental approaches: The group at the University of Duisburg-Essen focuses on the spectroscopy and dynamics of unoccupied electronic states near the center of the Brillouin zone using time- and angle-resolved photoemission (ARPES) and two-photon photoemission (2PPE) spectroscopy. The group at the Fritz Haber Institute in Berlin develops time-resolved XUV-based ARPES to study electron dynamics and electronic structure changes during photoinduced phase transitions throughout the complete Brillouin zone. The latter experiments will be complemented by time-resolved optical spectroscopy (SFG, RAS) in the regime of high laser fluence building on experiments with static optical spectroscopy (RAS) performed in E3. The ultrafast techniques employed in our project investigate the excited state electron dynamics. Within the Research Unit our activity forms together with projects T1 and T2, which theoretically treat changes in the electronic structure upon CDW formation and photo-induced phase transitions, and with project E7, which analyzes the complementary structural dynamics by femtosecond electron diffraction, a focus area on dynamics in 1D systems.