Ulrich Höfer

Affiliation: Philipps-University Marburg & University of Regensburg

Research Interests: Physics

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

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.