Vibrational spectra of In2S3, CuIn5S8 and AgIn5S8 compounds with a spinel structure

The IR reflection spectra of In2S3, CuIn5S8, AgIn5S8 compounds with a spinel structure are investigated. Using the DA-K-K method, we determined the frequencies of longitudinal and transverse phonons, attenuation coefficients of phonons, and IR intensities, as well as the dielectric constants e0 and e∞.