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.

Con tents

No abstract

Table 1 for 49 compounds (with Si and Ge for comparison) for which reasonably complete optical spectra are available. An asterisk indicates that E has been taken from an incomplete optical spectrum or from reflectivity measuremepts only. For alkali halides and II -VI compounds (following band structure calculations and electron energy loss spectra) we use n pounds and the thallous halides. The prelirninaryvalues of i in Table 1 are mostly reliable to 5 to 1% and the precision should improve as better optical spectra become av = 6 but n eff eff = 8 for m-Vcom-