Raman Spectroscopy and Chemical Bonding of BaFCl, BaFBr, and BaFl

Abstract

We investigated in detail the Raman scattering of barium fluorohalides BaFX (X = Cl, Br, I) in an effort to characterize changes in structure and chemical bonding. The overall picture that emerges from the BaFX Raman data is that with the compositional change from X = Cl → Br → I, electron density shifts from the axial Ba-X bond to the equatorial Ba-X bonds with compositional change to the heavier halide, and that the charge distribution becomes more delocalized in the halide layers. This change in electron density indicates an increase in covalency of the Ba-X bonds from Cl to I.