Photoemission Tomography and Quantum Dynamics

The banner image shows the temporal evolution of the photoelectron intensity of the two occupied LUMO orbitals of PTCDA adsorbed on Cu(001) after excitation (Wallauer, Science 2021).

About

The electronic wave functions of molecules, the orbitals, can be imaged in momentum space with photoemission tomography. With its help, we investigate the electronic structure and the chemical state of adsorbed molecules in detail, and even “observe the unobservable”: the complete quantum mechanical wave function including its phase can be reconstructed from photoemission tomographs.

This research is funded by an ERC Synergy Grant: Orbital Cinema.

Research Topics

  • Momentum microscopy and time-resolved photoemission orbital tomography
  • Electronic and chemical properties of organic molecules
  • Reconstructing molecular wave functions

Contact

Prof. Dr. Frank Stefan Tautz

PGI-3

Building 02.4w / Room 317

+49 2461/61-4561

E-Mail

Members

Dr. Sergey SubachSenior scientistBuilding 02.4w / Room 320+49 2461/61-3469
Dr. Andrei MatetskiiPostdocBuilding 02.4w / Room 135+49 2461/61-5950
Dr. Anja HaagsScientific coordinatorBuilding 02.4w / Room 326+49 2461/61-85879
Monja StettnerPhD studentBuilding 02.4w / Room 128+49 2461/61-6313
Eric FackelmanPhD studentBuilding 02.4w / Room 135+49 2461/61-5950

Research

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Toroidal Electron Analyser

For photoemission tomography experiments we run a unique toroidal electron analyser, located permanently at the Metrological Light Source (MLS) of the Physikalisch-Technische Bundesanstalt (PTB) in Berlin.

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Electronic and Chemical Properties of Organic Molecules

Over the last years and in collaboration with our colleagues at Karl-Franzens Universtiy in Graz we have developed photoemission tomography into a powerful technique that provides direct access to the orbital structure of molecules (in particular of frontier orbitals that determine the electronic, optical and chemical properties of molecules) and thus helps revealing electronic and chemical states of molecules at surfaces.

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Reconstructing Molecular Wave Functions

Based on photoemission tomography, we have developed a technique to reconstruct the real-space probability amplitude density of molecular orbitals including their quantum mechanical phase.

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Tracing Orbital Images on Ultrafast Time Scales

Following molecular excitation and electron transfer processes in time and space within a single experiment is a long-standing goal of spectroscopy in the field of chemistry. Wallauer et al. combined tomographic photoemission imaging with a femtosecond pump-probe scheme to trace the excited state molecular orbitals of surface-adsorbed molecules with both spatial and temporal resolution. The present demonstration opens a new window for investigating the ultrafast electron transfer dynamics in such processes as chemical reactions on surfaces and intermolecular charge transfers.

Recent Publications
  • A. Adamkiewicz, M. Raths, M. Stettner, M. Theilen, L. Münster, S. Wenzel, M. Hutter, S. Soubatch, C. Kumpf, F. C. Bocquet, R. Wallauer, F. S. Tautz, and U. Höfer, “Coherent and Incoherent Excitation Pathways in Time-Resolved Photoemission Orbital Tomography of CuPc/Cu(001)-2O”, J. Phys. Chem. C 127, 20411 (2023). https://doi.org/10.1021/acs.jpcc.3c04859
  • C. S. Kern, A. Haags, X. Yang, H. Kirschner, A. Gottwald, M. Richter, U. D. Giovannini, A. Rubio, M. G. Ramsey, F. Bocquet, S. Soubatch, F. S. Tautz, P. Puschnig, and S. Moser, “Simple extension of the plane-wave final state in photoemission: Bringing understanding to the photon-energy dependence of two-dimensional materials”, Phys. Rev. Research 5, 033075 (2023), Editor’s suggestion. https://doi.org/10.1103/PhysRevResearch.5.033075
  • A. Haags, X. Yang, L. Egger, D. Brandstetter, H. Kirschner, A. Gottwald, M. Richter, G. Koller, M. G. Ramsey, F. C. Bocquet, S. Soubatch, F. S. Tautz, and P. Puschnig, “Benchmarking theoretical electronic structure methods with photoemission orbital tomography”, arXiv:2209.11516 [cond-mat.mtrl-sci] (2022). https://doi.org/10.48550/arXiv.2209.11516
Last Modified: 10.01.2025
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