title: Evidence for Ionic Bonding in YH(3-delta).
abstract: The infrared transmission spectra of YH(3-delta) and YD(3-delta) thin films have been measured in the energy range from 300 to 6000 cm(-1), and the optical constants have been calculated by Kramers-Kronig analysis. From a fit of the frequency-dependent conductivity and the dielectric loss functions with one Drude term and five Lorentz oscillators, the longitudinal and transverse optical-phonon frequencies have been determined. The Born and Szigeti effective charges have been calculated and the ionicities of the ions in YH(3-delta) have been derived. We find that hydrogen does not enter as a proton in the compound, but that it is negatively charged, with a Szigeti effective charge of nearly 0.5e.
authors.affiliation: Institut für Halbleiterphysik und Optik, TU Braunschweig, Mendelssohnstrasse 3, D-38106 Braunschweig, Germany. ma.rode@tu-bs.de
authors.forename: M
authors.initials: M
authors.lastname: Rode
authors.forename: A
authors.initials: A
authors.lastname: Borgschulte
authors.forename: A
authors.initials: A
authors.lastname: Jacob
authors.forename: C
authors.initials: C
authors.lastname: Stellmach
authors.forename: U
authors.initials: U
authors.lastname: Barkow
authors.forename: J
authors.initials: J
authors.lastname: Schoenes