Resolving vibrations in a polyatomic molecule with femtometer precision via x-ray spectroscopy
Patrick Rupprecht, Lennart Aufleger, Simon Heinze, Alexander Magunia, Thomas Ding, Marc Rebholz, Stefano Amberg, N. M. Mollov, Felix Henrich, M. W. Haverkort, Christian Ott, Thomas Pfeifer
Abstract
We measure molecular vibrations with femtometer precision via resonance energy shifts using time-resolved x-ray absorption spectroscopy. For a demonstration, a Raman process excites the ${A}_{1g}$ mode in gas-phase ${\mathrm{SF}}_{6}$ molecules with an amplitude of approximately $50\phantom{\rule{4pt}{0ex}}\mathrm{fm}$, which is probed by a time-delayed soft-x-ray pulse at the sulfur ${L}_{2,3}$ edge. Mapping the extremely small measured energy shifts to internuclear distances requires an understanding of the electronic contributions provided by a many-body ab initio simulation. Our study establishes core-level spectroscopy as a precision tool for time-dependent molecular-structure metrology.