Potamianos Dionysios, Schnitzenbaumer Maximilian, Lemell Christoph, Scigalla Pascal, Libisch Florian, Schock-Schmidtke Eckhard, Haimerl Michael, Schröder Christian, Schäffer Martin, Küchle Johannes T, Riemensberger Johann, Eberle Karl, Cui Yang, Kleineberg Ulf, Burgdörfer Joachim, Barth Johannes V, Feulner Peter, Allegretti Francesco, Kienberger Reinhard
Physik Department, Technische Universität München, Garching, 85748, Germany.
Institute for Theoretical Physics, Vienna University of Technology, Vienna, 1040, Austria.
Sci Adv. 2024 Jun 28;10(26):eado0073. doi: 10.1126/sciadv.ado0073. Epub 2024 Jun 26.
We report on the energy dependence of the photoemission time delay from the single-element layered dielectric HOPG (highly oriented pyrolytic graphite). This system offers the unique opportunity to directly observe the Eisenbud-Wigner-Smith (EWS) time delays related to the bulk electronic band structure without being strongly perturbed by ubiquitous effects of transport, screening, and multiple scattering. We find the experimental streaking time shifts to be sensitive to the modulation of the density of states in the high-energy region ( ≈ 100 eV) of the band structure. The present attosecond chronoscopy experiments reveal an energy-dependent increase of the photoemission time delay when the final state energy of the excited electrons lies in the vicinity of the bandgap providing information difficult to access by conventional spectroscopy. Accompanying simulations further corroborate our interpretation.
我们报告了来自单元素层状电介质高定向热解石墨（HOPG）的光电子发射时间延迟的能量依赖性。该系统提供了独特的机会，可直接观察与体电子能带结构相关的艾森布德 - 维格纳 - 史密斯（EWS）时间延迟，而不会受到传输、屏蔽和多次散射等普遍存在的效应的强烈干扰。我们发现实验条纹时间偏移对能带结构高能区域（≈100 eV）中态密度的调制敏感。当前的阿秒计时实验表明，当激发电子的终态能量位于带隙附近时，光电子发射时间延迟随能量增加，这提供了传统光谱难以获取的信息。伴随的模拟进一步证实了我们的解释。
