The dielectric and lattice vibrational spectrum of cuprous oxide

The i.r. reflection and Raman spectra of single crystal specimens of cuprous oxide have been studied between 20 and 900 cm−1 over a wide temperature range. The optical and dielectric parameters have been derived by Kramers-Krönig analysis and the effective dynamic charge calculated. The Raman spectrum is far more complex than a group theoretical analysis suggests and this is interpreted in terms of a selection rule breakdown in the crystal due to nonstoichiometry. Variable temperature and polarisation measurements have been made in order to characterise some of the structure in the spectrum. The implications of the results for the lattice dynamical calculations is discussed.