Absorption Spectrum of RbMnF3

Abstract

Absorption spectrum of RbMnF₃ crystal has been studied at room temperature and at 77°K. The observed band positions are fitted with four parameters, B, C, Dq, and α, and the values of the parameters for the 77°K spectrum are 840, 3080, 780, and 76 cm⁻¹, respectively. The shift in band positions on reducing the temperature is attributed to an increase in Dq. Intensities of the two sharp bands assigned to the [⁴A_1g(G), ⁴E_g(G)] and ⁴E_g(D) levels are found to be higher than those of the broad bands. This enhancement of the intensities of the sharp bands is compared with the similar observations of earlier workers. Fine structure observed in the ⁴T_2g(D) band is attributed to the spin‐orbit splitting, and the analysis yields a value of 320 cm⁻¹ for the spin‐orbit coupling parameter ξ. Vibrational structure of the bands is analyzed by finding the vibrational modes of perovskite‐structured RbMnF₃.