Near-infrared luminescence of ferric oxide particles

A weak near-infrared luminescence has been observed for fine-particle Fe2O3 when excited by 1064 nm radiation from a Nd:YAG laser. There are three broad luminescence peaks at 7994, 7225 and 6686 cm(-1), with intensities about 10 times that of the Raman scattering. The relative intensities vary with particle morphology and with heat treatment. Overall band intensities increase by about a factor of 10 for Fe2O3 that has been heated to 500 degrees C and the decreases again for material that has been heated to 1000 degrees C. The emission was assigned to the T-4(1g) -> (6)A(1g) crystal field transition of octahedral Fe3+. A large Stokes shift is associated with these transitions. (c) 2005 Elsevier B.V. All rights reserved.