Abstract
The absorption spectrum of manganese formate dihy-drate has been studied at liquid nitrogen temperature (80 K) in the region λ 650 nm to 300 nm. Three bands of the spectrum resolved themselves exhibiting fine structure. The splitting of the 4Eg (G) band is explained as due to exciton-magnon interaction. Weak bands on either side of 4A1g (G) band are assigned to phonon progressions with = 0.12 kK. The fine structure of the 4T2g (D) band is explained as due to spin-orbit interaction. The observed band positions are fitted to four parameters B, C, ηq and α the best fit being obtained with B = 0.82 kK; C = 3.02 kK; Dq = 0.81 kK; α = 0.076 kK.