Electron-nuclear-double-resonance of the VAl center in MgO

An ENDOR study of a hole center in MgO with g_|=2.0032±0.0001 and g_⊥=2.0385±0.0001 reveals that the hole interacts with an axial aluminum ion with A_⊥=±0.178±0.008 MHz, A_⊥=±0.074±0.008 MHz, and P= ±0.366±0.002 MHz. The structure of the center is consistent with the label, V_Al. It is suggested that the V_Al center may have been mistaken in the past for the V^- center because of the similarity of their g-values, method of production, and thermal properties.