Optical Absorption Red Shift of Capped ZnFe₂O₄ Nanoparticle

Nanometer-sized ZnFe₂O₄ particles capped with a layer of surfactant are synthesized and their optical absorption is investigated. Such capped ZnFe₂O₄ particles present a strong band edge absorption in visible region and their energy band gap is estimated to be about 1.53eV. It is also found that the capped nanoparticles have a significant red shift of optical absorption band edge in contrast with that of uncapped ZnFe₂O₄ nanoparticles, which is mainly related to the trapped and self-trapped excitons absorption resulting from an interfacial dipole layer formed on the surface of ZnFe₂O₄ nanoparticles.