Identification of Vibrational Modes in BaSi_2 Epitaxial Films by Infrared and Raman Spectroscopy

摘要

Infrared (IR) absorption and polarized Raman spectra were measured in BaSi_2 epitaxial films to investigate the vibrational modes and the symmetry of Si_4 cluster in BaSi_2. By an analysis based on Raman and/or IR activity in the spectra, the symmetry of Si_4 cluster was determined as T_h-symmetry and the observed Raman lines and IR peaks were assigned to A_g, E_g, F_g, and F_u, respectively. In the three Raman lines of F_g-mode, one LO phonon line and two TO phonon lines were classified by the depolarization ratio of polarized Raman intensities.