title: Atomic insight to lattice distortions caused by carrier self-trapping in oxide materials.
abstract: We gain hitherto missing access to the spatio-temporal evolution of lattice distortions caused by carrier self-trapping in the class of oxide materials - and beyond. The joint experimental/theoretical tool introduced combines femtosecond mid-infrared probe spectroscopy with potential landscape modeling and is based on the original approach that the vibration mode of a biatomic molecule is capable to probe strongly localized, short-lived lattice distortions in its neighborhood. Optically generated, small, strong-coupling polarons in lithium niobate, mediated by OH-ions present as ubiquitous impurities, serve as a prominent example. Polaron trapping is found to result in an experimentally determined redshift of the OH-stretching mode amounting to Δνvib= -3 cm-1, that is successfully modeled by a static Morse potential modified by Coulomb potential changes due to the displacements of the surrounding ions and the trapped charge carrier. The evolution of the trapping process can also be highlighted by monitoring the dynamics of the vibrational shift making the method an important tool for studying various systems and applications.
authors.affiliation: Osnabrueck University, School of Physics, Barbarastraße 7, 49076 Osnabrueck, Germany.
authors.forename: Felix
authors.initials: F
authors.lastname: Freytag
authors.affiliation: Wigner Research Centre for Physics, Institute for Solid State Physics and Optics, Hungarian Academy of Sciences, Konkoly-Thege u. 29-33, 1121 Budapest, Hungary.
authors.forename: Gábor
authors.initials: G
authors.lastname: Corradi
authors.affiliation: Osnabrueck University, School of Physics, Barbarastraße 7, 49076 Osnabrueck, Germany.
authors.forename: Mirco
authors.initials: M
authors.lastname: Imlau