Freiburg 2024 – scientific programme

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MO: Fachverband Molekülphysik

MO 11: X-ray Spectroscopy

MO 11.1: Talk

Wednesday, March 13, 2024, 11:00–11:15, HS 3044

Photon-recoil imaging: Nonlinear X-ray physics in molecules — •L. Germeroth¹, M. Agåker², T. Baumann³, R. Boll³, A. De Fanis³, S. Eisebitt⁴, M. Génévriez⁵, V. Kimberg⁶, H. Lee¹, E. Marin-Bujedo⁵, T. Mazza³, M. Meyer³, J. Mikosch¹, Y. Ovcharenko³, S. Patchkovskii⁴, D. Reiser³, J.-E. Rubensson², J. Söderström², P. Schmidt³, B. Senfftleben³, A. Senftleben¹, S. Usenko³, and U. Eichmann⁴ — ¹Universität Kassel — ²Uppsala University — ³XFEL Hamburg — ⁴MBI Berlin — ⁵UCLouvain — ⁶KTH Stockholm

Non-linear Raman spectroscopy was originally developed for narrow-band lasers. It has since become important in the spectroscopy and microscopy of technological and biological processes. Stimulated Raman scattering with optical femtosecond lasers is routinely used to excite coherent vibrational and rotational wavepackets. The advance of ultrabright FELs enabled the extension of non-linear physics to the X-ray domain. Some of us have recently established photon-recoil imaging as a background-free technique to detect stimulated X-ray Raman scattering (SXRS) [1]. This process is similar to STIRAP, a form of state-to-state coherent control well known in the optical domain. Here we extend the pioneering experiments on Neon atoms to molecules. Near and far-off resonance SXRS in CO molecules populates efficiently an electronically excited long-lived metastable final state. Demonstration of far-off resonance SXRS in molecules opens new possibilities to study site-selective non-linear processes avoiding spontaneous decays. [1] Eichmann et al., Science 369, 1630 (2020)

Keywords: Raman scattering; X-ray physics; nonlinear physics; photon-recoil imaging