Department of Physics, Philipps University of Marburg, Germany

腾讯会议ID:  678-190-773

会议密码：1019

Abstract：

Time-resolved photoemission combines femtosecond pump-probe techniques with angle-resolved photoelectron spectroscopy (ARPES). Recent developments enable the method to track electron motion in two-dimensional momentum space on ultrafast time scales. This capability allows exploring ultrafast electronic processes of a variety of novel quantum materials by clear-cut experiments. In this talk, I will briefly introduce the state-of-the-art of the method and discuss a couple of examples from our recent work. These include bandstructure movies of the intraband acceleration of electrons in topologically protected Dirac surface states [1,2], of the birth and collapse of Floquet-Bloch states [3], and of the formation of momentum-forbidden and spin-forbidden dark excitons in TMDC monolayers [4]. Finally, I will outline the perspectives of photoemission orbital tomography [5] to take slow-motion movies of molecular orbitals while they are driven by lightwaves.

[1] J. Reimann et al., Nature 562, 396 (2018)

[2] C. P. Schmid et al., Nature 593, 385 (2021)

[3] S. Ito et al., Nature 616, 696 (2023)

[4] R. Wallauer et al., Nano. Lett. 21, 5867 (2021)

[5] R. Wallauer et al., Science 371, 1056 (2021)

Brief CV of Prof. Ulrich H fer:

Ulrich H fer received his doctoral degree in physics in 1989 from the Technical University of Munich, Germany. After spending two years as a visiting scientist at the IBM Watson Research Center in Yorktown Heights, New York, he joined the Max-Planck-Institute for Quantum Optics in Garching/Munich, as a group leader. In 1999, he became a full professor for experimental physics at the Philipps University of Marburg. Since 2022, he is also an adjunct professor of the University of Regensburg. H fer’s main research interests are ultrafast processes at surfaces and interfaces. He is a pioneer of time-resolved ARPES (angle-resolved photoemission spectroscopy) and coherent light-matter interaction at surfaces. His awards include the Arnold Sommerfeld prize of the Bavarian Academy of Sciences and a Synergy Research Grant from the European Research Council (ERC).

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