Siegfried Kaidisch » People

@article{Stettner2026,

title = {Tracing the film structure of an organic semiconductor with photoemission orbital tomography},

author = {M. Stettner and S. Kaidisch and Andrey V. Matetskiy and E. Fackelman and S. Soubatch and C. Kumpf and F. C. Bocquet and M. G. Ramsey and P. Puschnig and F. S. Tautz},

url = {https://arxiv.org/abs/2603.06204},

doi = {10.48550/arXiv.2603.06204},

year  = {2026},

date = {2026-03-06},

journal = {arXiv:2603.06204 [cond-mat.mtrl-sci]},

keywords = {},

pubstate = {forthcoming},

tppubtype = {article}

}

@article{Theilen2025,

title = {Observing the spatial and temporal evolution of exciton wave functions},

author = {M. Theilen and S. Kaidisch and M. Stettner and S. Zajusch and E. Fackelman and A. Adamkiewicz and R. Wallauer and A. Windischbacher and C. S. Kern and M. G. Ramsey and F. C. Bocquet and S. Soubatch and F. S. Tautz and U. Höfer and P. Puschnig},

url = {https://arxiv.org/abs/2511.23001},

doi = {10.48550/arXiv.2511.23001},

year  = {2025},

date = {2025-11-28},

urldate = {2025-11-28},

journal = { arXiv:2511.23001  [cond-mat.mtrl-sci]},

abstract = {Excitons, the correlated electron-hole pairs governing optical and transport properties in organic semiconductors, have long resisted direct experimental access to their full quantum-mechanical wave functions. Here, we use femtosecond time-resolved photoemission orbital tomography (trPOT), combining high-harmonic probe pulses with time- and momentum-resolved photoelectron spectroscopy, to directly image the momentum-space distribution and ultrafast dynamics of excitons in  -sexithiophene thin films. We introduce a quantitative model that enables reconstruction of the exciton wave function in real space, including both its spatial extent and its internal phase structure. The reconstructed wave function reveals coherent delocalization across approximately three molecular units and exhibits a characteristic phase modulation, consistent with ab initio calculations within the framework of many-body perturbation theory. Time-resolved measurements further show a  % contraction of the exciton radius within 400 fs, providing direct evidence of self-trapping driven by exciton-phonon coupling. These results establish trPOT as a general and experimentally accessible approach for resolving exciton wave functions -- with spatial, phase, and temporal sensitivity -- in a broad class of molecular and low-dimensional materials. },

keywords = {},

pubstate = {forthcoming},

tppubtype = {article}

}

@article{Kaidisch2025_arxiv,

title = {Photoemission tomography of excitons in 2D systems: momentum-space signatures of correlated electron-hole wave functions},

author = {S. Kaidisch and A. Kleiner and S. Refaely-Abramson and P. Puschnig and C. S. Kern},

url = {https://arxiv.org/abs/2511.14956},

doi = {10.48550/arXiv.2511.14956},

year  = {2025},

date = {2025-11-18},

urldate = {2025-11-18},

journal = { arXiv:2511.14956 [cond-mat.mtrl-sci]},

abstract = {The momentum-space signatures of excitons can be experimentally accessed through time-resolved (pump-probe) photoelectron spectroscopy. In this work, we develop a computational framework for exciton photoemission orbital tomography (exPOT) in periodic systems, enabling the simulation and interpretation of experimental observables within many-body perturbation theory. By connecting the  +Bethe-Salpeter Equation (BSE) approach to photoemission tomography, our formalism captures exciton photoemission in periodic systems, explicitly incorporating photoemission matrix element effects induced by the probe pulse. The correlated nature of electrons and holes introduces distinct consequences for excitonic photoemission, including a dependence on pump pulse polarization. Using the prototypical two-dimensional material hexagonal boron nitride, we demonstrate these effects and show how our framework extends to excitons with finite center-of-mass momentum, making it well-suited to studying momentum-dark excitons. This provides valuable insights into the microscopic nature of excitonic phenomena in quantum materials. },

keywords = {},

pubstate = {forthcoming},

tppubtype = {article}

}