Ions of V were studied by using electron paramagnetic resonance and photo-electron paramagnetic resonance techniques. On the basis of observations of the central hyperfine interaction, the electron paramagnetic resonance measurements were found to identify 2 V-related defects. These were attributed to V3+ and V2+; both of which substituted for Cd. Whereas V3+ exhibited the classic isotropic electron paramagnetic resonance spectrum, the V2+ spectrum featured a triclinic symmetry that was caused by a strong Jahn-Teller coupling to both the 2 and  vibronic modes. By means of photo-electron paramagnetic resonance, the V2+/V3+-donor level was determined to be located 0.67eV below the conduction band.

P.Christmann, B.K.Meyer, J.Kreissl, R.Schwarz, K.W.Benz: Physical Review B, 1996, 53[7], 3634-7