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 °C and the decreases again for material that has been heated to 1000 °C. The emission was assigned to the 4T1g→6A1g crystal field transition of octahedral Fe3+. A large Stokes shift is associated with these transitions.