Phonon effects in Yb3+ and Nd3+ spectra of GdCOB

A review of the results obtained from the low temperature selective excitation and emission spectra of Nd3+ and Yb3+ in GdCa4O(BO3)3, GdCOB, is presented. The non-equivalent sites and inhomogeneous line widths of zero-phonon lines indicate the partially disordered character of this crystal. The large vibronics and homogeneous broadening for Nd3+ and Yb3+ suggest a strong coupling to the lattice. The vibronic structure characteristics for two Yb3+ centers is analyzed.