title: Vibrational property study of SrGa2H2 and BaGa2H2 by inelastic neutron scattering and first principles calculations.
abstract: Vibrational properties of the gallium hydrides SrGa2H2 and BaGa2H2 have been investigated by means of inelastic neutron scattering (INS) and first-principles calculations. The compounds contain Ga-H units being part of a two-dimensional polyanionic layer, [(GaH)(GaH)]2-. The INS spectra are composed of dispersed internal Ga-H bending and stretching modes at frequencies above 600 cm(-1) and external lattice modes at frequencies below 220 cm(-1). Frequencies of the internal modes are not susceptible to the metal countercation, indicating a strong integrity of the polyanionic layer as a building unit in the structures of SrGa2H2 and BaGa2H2. The Ga-H stretching modes have frequencies between 1200 and 1400 cm(-1), which is very low compared to molecular gallium hydrides. The weak Ga-H bond in SrGa2H2 and BaGa2H2 is balanced by Sr(Ba)-H interactions.
authors.affiliation: Department of Physics, Arizona State University, P.O. Box 871504 Tempe, Arizona 85287-1504, USA.
authors.forename: Myeong H
authors.initials: MH
authors.lastname: Lee
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Evans
authors.forename: Luke L
authors.initials: LL
authors.lastname: Daemen
authors.forename: Otto F
authors.initials: OF
authors.lastname: Sankey
authors.forename: Ulrich
authors.initials: U
authors.lastname: Häussermann