Study of vanadium complexes in potassium oxalate monohydrate crystals

The optical absorption of VO2+ doped K2C 2O4:H2O has been studied at 300 and 77°K. The existence of vanadyl ion in the crystal was verified by IR absorption study. Four optical peaks corresponding to d-d transitions and an intense peak at 28900 cm-1 due to charge transfer have been recorded at 300°K. The identity of charge transfer band was established by polarization studies. At 77°K the band at 15 384 cm-1 showed vibronic structure with a separation ∼755 cm-1. The spectra have been interpreted in terms of both molecular orbital (MO) theory and crystal field theory. Radiation damage studies of VO2+ doped K2C2O 4·H2O revealed the formation of VO2. The two bands due to d-d transitions in VO2 and other optical peaks due to interband transitions have been recorded for parallel and perpendicular polarizations of light. This evidence for the formation of VO2 has been discussed. © 1980 American Institute of Physics.