title: Gradual collapse of nuclear wave functions regulated by frequency tuned X-ray scattering.
abstract: As is well established, the symmetry breaking by isotope substitution in the water molecule results in localisation of the vibrations along one of the two bonds in the ground state. In this study we find that this localisation may be broken in excited electronic states. Contrary to the ground state, the stretching vibrations of HDO are delocalised in the bound core-excited state in spite of the mass difference between hydrogen and deuterium. The reason for this effect can be traced to the narrow "canyon-like" shape of the potential of the state along the symmetric stretching mode, which dominates over the localisation mass-difference effect. In contrast, the localisation of nuclear motion to one of the HDO bonds is preserved in the dissociative core-excited state . The dynamics of the delocalisation of nuclear motion in these core-excited states is studied using resonant inelastic X-ray scattering of the vibrationally excited HDO molecule. The results shed light on the process of a wave function collapse. After core-excitation into the state of HDO the initial wave packet collapses gradually, rather than instantaneously, to a single vibrational eigenstate.
authors.affiliation: Theoretical Chemistry and Biology, Royal Institute of Technology, S-10691, Stockholm, Sweden.|Institute of Nanotechnology, Spectroscopy and Quantum Chemistry, Siberian Federal University, 660041, Krasnoyarsk, Russia.
authors.forename: Nina
authors.initials: N
authors.lastname: Ignatova
authors.affiliation: Theoretical Chemistry and Biology, Royal Institute of Technology, S-10691, Stockholm, Sweden.
authors.forename: Vinícius V
authors.initials: VV
authors.lastname: Cruz
authors.affiliation: Theoretical Chemistry and Biology, Royal Institute of Technology, S-10691, Stockholm, Sweden.|Instituto de Química, Universidade Federal de Goiás, Campus Samambaia, CP 131 CEP 74001-970, Goiânia-GO, Brazil.
authors.forename: Rafael C
authors.initials: RC
authors.lastname: Couto
authors.affiliation: Department of Physics, Stockholm University, AlbaNova University Center, 10691, Stockholm, Sweden.
authors.forename: Emelie
authors.initials: E
authors.lastname: Ertan
authors.affiliation: Theoretical Chemistry and Biology, Royal Institute of Technology, S-10691, Stockholm, Sweden.|Institute of Nanotechnology, Spectroscopy and Quantum Chemistry, Siberian Federal University, 660041, Krasnoyarsk, Russia.
authors.forename: Andrey
authors.initials: A
authors.lastname: Zimin
authors.affiliation: Instituto de Química, Universidade Federal de Goiás, Campus Samambaia, CP 131 CEP 74001-970, Goiânia-GO, Brazil.
authors.forename: Freddy F
authors.initials: FF
authors.lastname: Guimarães
authors.affiliation: Institute of Nanotechnology, Spectroscopy and Quantum Chemistry, Siberian Federal University, 660041, Krasnoyarsk, Russia.
authors.forename: Sergey
authors.initials: S
authors.lastname: Polyutov
authors.affiliation: Theoretical Chemistry and Biology, Royal Institute of Technology, S-10691, Stockholm, Sweden.
authors.forename: Hans
authors.initials: H
authors.lastname: Ågren
authors.affiliation: Theoretical Chemistry and Biology, Royal Institute of Technology, S-10691, Stockholm, Sweden.|Institute of Nanotechnology, Spectroscopy and Quantum Chemistry, Siberian Federal University, 660041, Krasnoyarsk, Russia.
authors.forename: Victor
authors.initials: V
authors.lastname: Kimberg
authors.affiliation: Department of Physics, Stockholm University, AlbaNova University Center, 10691, Stockholm, Sweden.
authors.forename: Michael
authors.initials: M
authors.lastname: Odelius
authors.affiliation: Theoretical Chemistry and Biology, Royal Institute of Technology, S-10691, Stockholm, Sweden.|Institute of Nanotechnology, Spectroscopy and Quantum Chemistry, Siberian Federal University, 660041, Krasnoyarsk, Russia.
authors.forename: Faris
authors.initials: F
authors.lastname: Gel'mukhanov