Low-temperature Photoluminescence of CoO excited by Synchrotron Radiation

We report the first observation of low-temperature luminescence of CoO crystals under synchrotron irradiation. At 8 K, the photoluminescence of CoO is characterized by smaller bandwidth and higher intensity relative to the corresponding photoluminescence band of NiO. The photoluminescence excitation spectra of CoO and NiO are similar. Position of the band related to charge transfer from oxygen ions to 3d-shell of cobalt ions is determined. The excitation energy is found to be 3.5 eV