Temperature dependence of infrared-absorption lines ofCo2+in cadmium halides

A. P. Vink, A. Meijerink, G. D. Jones
2002 Physical Review B (Condensed Matter)  
Temperature-dependent infrared-absorption measurements were performed on the spin orbit and trigonalcrystal-field split levels of the 4 T 1g cubic-field ground term of Co 2ϩ (3d 7 ) in the cadmium halides CdX 2 ͑X: Cl, Br, and I͒. Besides ␥ 4 ϩ →␥ 4 ϩ and ␥ 4 ϩ →␥ 5,6 ϩ electronic transitions, sharp vibronic lines are observed. From temperature-dependent line shift and line-broadening measurements of these lines, electron-phonon coupling parameters were determined. For Co 2ϩ in CdCl 2 , where
more » ... in CdCl 2 , where the energy separation of the ␥ 4 ϩ and ␥ 5,6 ϩ levels studied is comparable to the phonon energies, a contribution from direct one-phonon processes needs to be included. Further line-shift measurements were made on Co 2ϩ pair lines to determine whether the electron-phonon coupling differed for Co 2ϩ pairs, with no significant difference being observed. The infrared-absorption spectrum for Co 2ϩ in CdI 2 is reported.
doi:10.1103/physrevb.66.134303 fatcat:akwjoz4kdzavpba52zqnrbvgc4