FAR-INFRARED SPECTROSCOPIC INVESTIGATIONS ON CUO

Far-infrared reflection spectra of a polycrystalline sample of monoclinic CuO were measured in the frequency range from 30 to 700 cm-1 at temperatures between 10 and 300 K. The six observed lattice vibrational modes at 147, 161, 321, 478, 533, and 587 cm-1 (300 K) were assigned by comparison with those of PdO using Cartesian symmetry coordinates. Normal coordinates were calculated within a short-range valence-force-field model. A broad mode at about 414 cm-1 at 300 K, whose intensity changes drastically as the temperature is lowered, may be explained in terms of magnetic ordering in CuO. © 1990 The American Physical Society.