The optical constants of aluminium oxide from 12.0 to 24.4 eV

The optical constants of aluminium oxide have been determined from reflection measurements made at 5° intervals from 30° to 70° using an interative-type computer programme. The samples were prepared by anodization of evaporated aluminium in ammonium tartrate solution. The results are self consistent within ±10% and indicate a maximum in the extinction coefficient of 1.1 at about 12 ev and a minimum at energies just above 25 ev. The refractive index has a minimum value of 0.61 at 21 ev. The results are compared with those of other authors.