Speaker
Description
Understanding and control of photon-induced dynamics of molecules on solid surfaces are of essential importance for surface chemistry as well as for design of novel devices. Here, such a multiview experiment is realized by integrating four modalities of time-resolved photoelectron spectroscopy—time-resolved orbital tomography, trARPES, trXPS, and trXPD—using ultrashort-pulsed extreme ultraviolet and soft x-ray radiation for valence- and core-electron emission.
In our contribution, we go beyond time-resolved orbital tomography [2] and correlate these data with time-resolved information on the chemical state, band structure evolution of the 2D quantum material, and structural information of the molecule - all in real time and simultaneously. This opens up the possibility of observing the evolution of the wave function during a reaction in real time. In our detailed analysis, we discover a new mechanism that triggers the unprecedented rotation of a large ensemble of molecules. We find that the rotation is triggered by a complex interplay between hot carrier transfer, modification of the wave function, a global shift of all 2D material bands, charging of the film, and a chiral symmetry breaking in the molecules. We show how the macroscopic and microscopic worlds are connected in dynamically driven reactions on surfaces. Using theory, we explain a new mechanism for how gear motion can be realized in a large ensemble of molecules on a 2D quantum material.
Our results provide a preview of upcoming experiments at the high-repetition-rate free-electron lasers European XFEL and LCLS-II, where we are currently setting up a similar experimental approach.
References
[1] P. Puschnig, S. Berkebile, A. J. Fleming, G. Koller, K. Emtsev, T. Seyller, J. D. Riley, C. Ambrosch-Draxl, F. P. Netzer, M. G. Ramsey, Reconstruction of molecular orbital densities from photoemission data. Science. 326, 702–706 (2009).
[2] K. Baumgärtner, M. Reuner, C. Metzger, D. Kutnyakhov, M. Heber, F. Pressacco, C.-H. Min, T. R. F. Peixoto, M. Reiser, C. Kim, W. Lu, R. Shayduk, M. Izquierdo, G. Brenner, F. Roth, A. Schöll, S. Molodtsov, W. Wurth, F. Reinert, A. Madsen, D. Popova-Gorelova, M. Scholz, Ultrafast orbital tomography of a pentacene film using time-resolved momentum microscopy at a FEL. Nat Commun. 13, 2741 (2022).
| Keywords | free-electron laser, FEL, photoemission, electronic, structural, dynamics, 2D quantum material, molecule |
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