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One-dimensional cuts through multidimensional potential-energy surfaces by tunable x rays

Type of publication Peer-reviewed
Publikationsform Original article (peer-reviewed)
Author Eckert Sebastian, da Cruz Vinícius Vaz, Gel'mukhanov Faris, Ertan Emelie, Ignatova Nina, Polyutov Sergey, Couto Rafael C., Fondell Mattis, Dantz Marcus, Kennedy Brian, Schmitt Thorsten, Pietzsch Annette, Odelius Michael, Föhlisch Alexander,
Project Coupled spin, charge and orbital dynamics of low-dimensional cuprates
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Original article (peer-reviewed)

Journal Physical Review A
Volume (Issue) 97(5)
Page(s) 053410 - 053410
Title of proceedings Physical Review A
DOI 10.1103/physreva.97.053410

Open Access

Type of Open Access Publisher (Gold Open Access)


The concept of the potential-energy surface (PES) and directional reaction coordinates is the backbone of our description of chemical reaction mechanisms. Although the eigenenergies of the nuclear Hamiltonian uniquely link a PES to its spectrum, this information is in general experimentally inaccessible in large polyatomic systems. This is due to (near) degenerate rovibrational levels across the parameter space of all degrees of freedom, which effectively forms a pseudospectrum given by the centers of gravity of groups of close-lying vibrational levels. We show here that resonant inelastic x-ray scattering (RIXS) constitutes an ideal probe for revealing one-dimensional cuts through the ground-state PES of molecular systems, even far away from the equilibrium geometry, where the independent-mode picture is broken. We strictly link the center of gravity of close-lying vibrational peaks in RIXS to a pseudospectrum which is shown to coincide with the eigenvalues of an effective one-dimensional Hamiltonian along the propagation coordinate of the core-excited wave packet. This concept, combined with directional and site selectivity of the core-excited states, allows us to experimentally extract cuts through the ground-state PES along three complementary directions for the showcase H2O molecule.