Nov 21, 2024

Title: Time-resolved photoemission: From bandstructure to orbital movies

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Speaker: Prof. Ulrich Höfer (Department of Physics, Philipps University of Marburg, Germany)

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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, in the case of THz and MIR pump radiation with subcycle resolution. 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.

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Reference

[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)