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Ultrafast orbital tomography of a pentacene film using time-resolved momentum microscopy at a FEL

2022; Nature Portfolio; Volume: 13; Issue: 1 Linguagem: Inglês

10.1038/s41467-022-30404-6

2041-1723

Kiana Baumgärtner, Marvin Reuner, Christian Metzger, Dmytro Kutnyakhov, Michael Heber, Federico Pressacco, Chul-Hee Min, T. R. F. Peixoto, Mario Reiser, Chan Kim, Wei Lu, Roman Shayduk, M. Izquierdo, Günter Brenner, Friedrich Roth, A. Schöll, С. Л. Молодцов, W. Würth, F. Reinert, Anders Madsen, Daria Popova-Gorelova, Markus Scholz,

Mechanical and Optical Resonators

We use time-resolved momentum microscopy at a free-electron laser (FEL) and extend orbital tomography into the time domain to image the electronic wave functions of excited molecular orbitals. This technique provides unprecedented insight into the ultrafast interplay between structural and electronic dynamics. In this work we prove general applicability and establish the experimental conditions at FEL sources to minimize space charge effects and radiation damage. We investigate a bilayer pentacene film on Ag(110) by optical laser pump and FEL probe experiments. From the momentum microscopy signal, we obtain time-dependent momentum maps of the excited-state dynamics of both pentacene layers separately. Combining experimental observations with a theoretical study, we interpret the observed signal for the bottom layer as resulting from the charge redistribution between the molecule and the substrate induced by excitation. We identify that the dynamics of the top pentacene layer resembles excited-state molecular dynamics.