Total Reflection of X-Rays from Nickel Films of Various Thicknesses

The total reflection of x-rays ($\lambda =0.707\mathrm{}\mathrm{A}$) is obtained from mirrors of sputtered nickel films having thicknesses from 0 to 3.3×${10}^{-5\mathrm{}}$ cm. The measured critical angles were found to vary from a minimum value of 0.0016 radians, that of blank glass, to a maximum value of 0.00339 radians, which was obtained from the thickest nickel film. A satisfactory agreement between the maximum experimental value of the critical angle and that calculated by the Lorentz dispersion formula in which the density of nickel was placed at 8.75 gm/cc, is used as evidence for concluding that the density of the nickel is entirely normal and also that the thickness of sputtered metal films which are to be used in x-ray reflection phenomena must be sufficiently large or misleading results may be obtained. The critical angle from a thick silver sputtered mirror was found to be identical with that obtained from a chemically prepared silver mirror which indicates that the density of silver is independent of the method of deposition.