Speaker
Description
It is a long-standing goal of surface and interface science to simultaneously image atomic positions, molecular orbital wavefunctions, and electronic-state dynamics as bonds and bands rearrange in time. Here, we realize this in a single experimental scheme by combining four modalities of time-resolved photoelectron spectroscopy: trARPES, tr-orbital tomography, trXPS, and trXPD—using ultrashort XUV/soft-X-ray pulses and a time-of-flight momentum microscope.
In a combined experimental and theoretical study, we investigate the ultrafast dynamics of an adsorbed molecular layer on the surface of a 2D quantum material. We disentangle how charge and energy transfer across the interface drive structural rearrangements, collective molecular rotation, and the emergence of homochiral domains. Efficient charge injection into the molecular layer transiently modifies the molecular wavefunction, deforms the molecules, and reshapes the interfacial energy landscape, thereby initiating rotational motion. Our results demonstrate a route toward multidimensional ultrafast imaging of surface and interface dynamics at high-repetition-rate FELs such as FLASH, European XFEL, and LCLS-II.
Baumgärtner, .. , Scholz, et. al. Femtosecond concerted rotation of molecules on a 2D material interface. Nat Commun 17, 2110 (2026) https://doi.org/10.1038/s41467-026-69801-6