ABSORPTION SPECTRA OF MnF2, KMnF3, RbMnF3, AND CsMnF3

Abstract

Absorption spectra in the 3 000–4 000 Å region are presented for MnF₂, KMnF₃, RbMnF₃, and CsMnF₃ at room temperature, liquid-air temperature, and liquid-helium temperature. The spectra are similar at room temperature, but at low temperatures some differences appear. The 4.2 °K spectra of KMnF₃ and CsMnF₃ show evidence of splittings due to exchange-coupled ion pairs, and an estimate is made of the exchange-coupling constant for the excited states. The spectrum of KMnF₃ shows two lines associated with a ⁴Γ₃ level, which may be satellites caused by the magnetic phase transition. The spectra were examined in external magnetic fields up to 100 000 Oe, and no splitting or shiftings of the lines were observed. Crystal field parameters were calculated by fitting the room-temperature spectra.