MoO3 layers — optical properties, colour centres, and holographic recording

The spectral variations of optical absorption and refractive index are reported for thin layers of molybdenum trioxide prepared by evaporation in vacuum. These layers can be coloured by ultraviolet light and the absorption spectra of coloured layers show a single broad absorption band centred at 850 nm. The appearance of the colour centre absorption and the associated changes in the intrinsic edge have been used to record stable ‘thin’ holograms. A short discussion is given of the electronic structure of MoO3 and of the defects responsible for coloration.