Polarized electronic infrared spectra of CoCl2single crystals

摘要

Polarized infrared absorption spectra of single crystal CoCl2from 8 to 300 deg;K with light propagated parallel and perpendicular to the trigonal axis are reported. At 8deg;K spectra are presented in magnetic fields from 3 to 43 kG. Three polarized lines arising from magnetic dipole transitions are identified as transitions to electronic levels within the lower4T1gmanifold of a Co2plus;ion. A line at 956 cmminus;1(3 kG) and 960 cmminus;1(43 kG) of oscillator strength1.65times; 10minus;8, and a second line at 977 cmminus;1(3 kG) and 980 cmminus;1(43 kG) of oscillator strength2.5times; 10minus;8, are transitions to components of a Kramers doublet. Their separation of 21 cmminus;1measures the splitting of an excited electronic level of a Co2plus;ion in the exchange field of ground state neighbors. A third line at 1007 cmminus;1(3 kG) and 1010 cmminus;1(43 kG) is the transition to the next higher Kramers doublet whose exchange splitting is not resolved. Calculations of positions, polarizations, and oscillator strengths of magnetic dipole transitions are in accord with the observations. A broad band is observed at 8 deg;K between 1100 and 1500 cmminus;1. A structured absorption between 300 and 600 cmminus;1is reported in the unpolarized axial spectrum.