title: Anomalously strong two-electron one-photon X-ray decay transitions in CO caused by avoided crossing.
abstract: The unique opportunity to study and control electron-nuclear quantum dynamics in coupled potentials offered by the resonant inelastic X-ray scattering (RIXS) technique is utilized to unravel an anomalously strong two-electron one-photon transition from core-excited to Rydberg final states in the CO molecule. High-resolution RIXS measurements of CO in the energy region of 12-14 eV are presented and analyzed by means of quantum simulations using the wave packet propagation formalism and ab initio calculations of potential energy curves and transition dipole moments. The very good overall agreement between the experimental results and the theoretical predictions allows an in-depth interpretation of the salient spectral features in terms of Coulomb mixing of "dark" with "bright" final states leading to an effective two-electron one-photon transition. The present work illustrates that the improved spectral resolution of RIXS spectra achievable today may call for more advanced theories than what has been used in the past.
authors: Theoretical Chemistry &Biology, School of Biotechnology, Royal Institute of Technology, S-106 91 Stockholm, Sweden.|Instituto de Química, Universidade Federal Goiás, Campus Samambaia, CP 131, 74001-970 Goiânia, Goiás, Brazil.
authors: Rafael C
authors: RC
authors: Couto
authors: Laboratorio Nacional Luz Sincrotron, 10000 Campinas, Brazil.|Sorbonne Universités, UPMC Univ Paris 6, UMR7614, Laboratoire de Chimie Physique - Matière et Rayonnement, F-75005 Paris, France.
authors: Marco
authors: M
authors: Guarise
authors: Synchrotron SOLEIL, l'Orme des Merisiers, Saint-Aubin, BP 48, 91192 Gif-sur-Yvette Cedex, France.
authors: Alessandro
authors: A
authors: Nicolaou
authors: Synchrotron SOLEIL, l'Orme des Merisiers, Saint-Aubin, BP 48, 91192 Gif-sur-Yvette Cedex, France.
authors: Nicolas
authors: N
authors: Jaouen
authors: Sorbonne Universités, UPMC Univ Paris 6, UMR7614, Laboratoire de Chimie Physique - Matière et Rayonnement, F-75005 Paris, France.
authors: Gheorghe S
authors: GS
authors: Chiuzbăian
authors: Sorbonne Universités, UPMC Univ Paris 6, UMR7614, Laboratoire de Chimie Physique - Matière et Rayonnement, F-75005 Paris, France.
authors: Jan
authors: J
authors: Lüning
authors: Department of Physics and Astronomy, Uppsala University, Box 516, 751 20 Uppsala, Sweden.
authors: Victor
authors: V
authors: Ekholm
authors: Department of Physics and Astronomy, Uppsala University, Box 516, 751 20 Uppsala, Sweden.
authors: Jan-Erik
authors: JE
authors: Rubensson
authors: MAX IV Laboratory, Lund University, Box 118, 221 00 Lund, Sweden.
authors: Conny
authors: C
authors: Såthe
authors: MAX IV Laboratory, Lund University, Box 118, 221 00 Lund, Sweden.
authors: Franz
authors: F
authors: Hennies
authors: Theoretical Chemistry &Biology, School of Biotechnology, Royal Institute of Technology, S-106 91 Stockholm, Sweden.
authors: Victor
authors: V
authors: Kimberg
authors: Instituto de Química, Universidade Federal Goiás, Campus Samambaia, CP 131, 74001-970 Goiânia, Goiás, Brazil.
authors: Freddy F
authors: FF
authors: Guimarães
authors: Theoretical Chemistry &Biology, School of Biotechnology, Royal Institute of Technology, S-106 91 Stockholm, Sweden.
authors: Hans
authors: H
authors: Agren
authors: Theoretical Chemistry &Biology, School of Biotechnology, Royal Institute of Technology, S-106 91 Stockholm, Sweden.
authors: Faris
authors: F
authors: Gel'mukhanov
authors: Sorbonne Universités, UPMC Univ Paris 6, UMR7614, Laboratoire de Chimie Physique - Matière et Rayonnement, F-75005 Paris, France.
authors: Loïc
authors: L
authors: Journel
authors: Sorbonne Universités, UPMC Univ Paris 6, UMR7614, Laboratoire de Chimie Physique - Matière et Rayonnement, F-75005 Paris, France.
authors: Marc
authors: M
authors: Simon