The Reflection of X-Rays by Plane Surfaces

The reflection of the $K{\alpha }_1$ radiation of molybdenum by plane surfaces of glass and quartz and by sputtered films of nickel, platinum, and silver has been investigated. It was found that the critical angle of reflection of nickel was smaller for transparent films than for opaque ones. The critical angles for both nickel and platinum were lower than the values calculated from the electron theory. The experimental value for the critical angle of silver agreed with the theoretical within the limits of error of the experiment. Doan has found experimental values of the critical angle for films of a number of metals that agree with those predicted by the theory, and Edwards has obtained similar results using solid reflectors. If it is to be granted that the theory does hold true in the case of nickel and platinum, too, it is necessary to assume that the densities of sputtered films of nickel and platinum are less than those of the metals. Further it must be assumed that in the case of nickel the density varies with the thickness of the film, being smaller for the thinner films.