Site-selective fluorescence excitation spectroscopy of a KMgF3:Sm2+ crystal

Abstract We investigate the defect structure of KMgF3:Sm2+ by site-selective laser spectroscopy. The transitions between 5 D 0 and 7 F J (J=0, 1 and 2) states of Sm2+ in KMgF3 strictly obey induced electric dipole (ED) and magnetic dipole (MD) selection rules and symmetry selection rules from which three dominant sites with Oh, C4v and C2v symmetries and two minor C3v sites are identified at 11 K. The sites with C4v and C2v symmetries are assigned to Sm2+ with the vacancies at the nearest-neighbor K+ site along the [1 0 0] direction and at the second-nearest-neighbor K+ site along the [1 1 0] direction, respectively. It is assumed that the two C3v sites do not come from Sm2+ with the third-nearest-neighbor K+ vacancy along the [1 1 1] direction but from Sm2+ associated with other defects.