Title:    Time-resolved photoemission orbital tomography of molecular excitation at surfaces and interfaces

Time:    2025-10-23 10:00

Lecturer:  Prof. Ulrich Höfer

University of Regensburg

Venue:    Conference room 2, Energy Materials Building 3, Xiang 'an Campus

Abstract：

Photoemission orbital tomography (POT) is a powerful technique, by which the electron distribution in orbitals of well-ordered molecules at solid surfaces can be imaged in momentum space. We have recently combined the method with laser-pump probe techniques and investigated the dynamics of charge transfer processes at molecular interfaces. In this talk, I will first review the basic principles of time-resolved photoemission orbital tomography (tr-POT) and briefly discuss these results. Then, I will present recent progress in imaging exciton wavefunctions in organic semiconductors. Finally, I will outline a promising strategy to time-resolve surface bond formation with tr-POT by driving the molecular frame by strong THz pulses and performing photoelectron spectroscopy with subcycle time resolution.

Bio of Ulrich Höfer：

Ulrich Höfer 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. Höfer’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).