Optical Absorption of NaMnF3

Abstract

Optical absorption of a NaMnF₃ single crystal has been studied at 300°K and 80°K. The scheme of fitting the band positions involves four parameters B, C, Dq and α. With α fixed at its free ion value (76 cm⁻¹) the values of B, C, and Dq at 80°K are found to be 845, 3040, and 775 cm⁻¹, respectively. Vibrational progressions are observed in the fine structure of some of the bands at 80°K from which approximate vibration frequencies of the crystal have been determined and compared with those of other perovskite fluorides. Some of the bands observed above 35 000 cm⁻¹ are identified with the simultaneous electronic excitation of Mn²⁺ ion pairs.