EPR and optical absorption studies of V O2+ ions in L-asparagine monohydrate

Electron paramagnetic resonance (EPR) studies of V O2+ ions in L-asparagine monohydrate single crystals are reported at room temperature. It is found that the V O2+ ion takes up an interstitial site. The angular variations of the EPR spectra in three mutually perpendicular planes are used to determine the principal g and A values and their direction cosines. The values of g and A parameters are: gx=1.9011, gy=2.1008, gz=1.9891 and Ax=100, Ay=78, Az=126 (×10−4) cm−1. The optical absorption spectrum of V O2+ ions in L-asparagine monohydrate is also studied at room temperature. The band positions are calculated using the energy expressions and compared with the observed band positions to confirm the transitions. The best-fit values of the crystal field (Dq) and tetragonal (Ds and Dt) parameters are evaluated from the observed band positions.