Far-infrared reflectance spectra of A2CuCl4,2H2O (A = NH4, K, or Rb) single crystals: copper–chlorine vibrations of the distorted octahedral aquochlorocuprate(II) anion

Abstract

The polarised far-i.r. reflectance spectra of A2CuCl4,2H2O (A = NH4, K, or Rb) single crystals have been recorded in the region 40–400 cm–1. These have permitted the observation and assignment of most of the predicted bands, including one at ca. 180 cm–1 due predominantly to the ‘long’ Cu–Cl stretching mode. Anomalies in the reflectance spectra of (111) faces of these crystals are discussed.