Fourier transform infrared spectra and normal vibrations of CuO

Abstract

The Fourier transform infrared spectra of CuO were recorded in the region 15-1000 cm^-1 at 300 K and 90 K. Combining our IR data with Raman data of Cu¹⁶O and Cu¹⁸O from the literature, a normal coordinate analysis has been carried out for the crystallographic unit cell of CuO. This has given detailed assignments and atomic displacements for all the normal modes and also expected infrared frequency values of (Cu¹⁸O). It has also provided a reasonable set of force constants which would enable one to calculate the frequency values for other copper-oxygen compounds. A band was found to develop at 418 cm^-1 at liquid N₂ temperature and this is assigned as a possible transition from the spin wave excitation to the Au vibrational level at 444 cm^-1. All the weaker observed IR bands are satisfactory explained as combination bands.