Cornelius Petrus
Groen, Attila Kovács
Matrix-isolation FT-IR study of (CsBr)n and (CsI)n
(n=1-3)
Vibrational Spectroscopy, 54 (2010) 30-34
The species present in the vapours
of CsBr and CsI have been
isolated in krypton and xenon matrices and were investigated by FT-IR
spectroscopy in the range of 180-30 cm-1. The recorded spectra
revealed the presence of substantial amounts of dimer
beside the alkali halide monomers. The assignment of the bands and
characterization of the fundamentals was carried out on the basis of DFT
quantum chemical calculations. The applied B3P86 exchange-correlation
functional in conjunction with the Stuttgart-Cologne relativistic effective
core potentials and polarized triple-zeta valence basis set reproduced the
accurate experimental monomer Cs–Br and Cs–I bond distances within
0.001 Å, and the harmonic stretching frequency within 1.1 cm-1.
Based on calculations at this level we report reliable geometrical parameters
and fundamental frequencies for the dimer and trimer species (CsBr)n
and (CsI)n. Utilizing the computed data we
propose the identification of the E’ asymmetric stretching mode of the trimer (CsI)3 trapped
in a Xe matrix and that of (CsBr)3
in Kr and Xe matrices.
