The Fine Structure of Certain X-Ray Absorption Edges

Abstract

X-ray absorption edges for certain elements and compounds.—In a recent paper ${\mathrm{Coster}}^1$ reports a white line on the long wave-length side of the x-ray absorption edge of some metallic oxides. Evidence is here reported which shows that in each case the white line is the absorption edge for some of the material which had been reduced to the metal by the x-ray beam. Screens were prepared by covering black paper with a thin layer of finely divided metal weighing 2 to 3 mg per ${\mathrm{cm}}^2$. (1) $K$ absorption edges for $\mathrm{Ti}\left(22\right)\mathrm{}$, $V\left(23\right)\mathrm{}$, $\mathrm{Cr}\left(24\right)\mathrm{}$ and $\mathrm{Mn}\left(25\right)\mathrm{}$ were found at 2489.5, 2261.9, 2064.9 and 1891.4 x-units. (2) $L_{\mathrm{III}}$ absorption edges for $\mathrm{Sn}\left(50\right)\mathrm{}$, $\mathrm{Sb}\left(51\right)\mathrm{}$ $\mathrm{Te}\left(52\right)\mathrm{}$ and $I\left(53\right)\mathrm{}$ are 3146.9, 2291.5, 2847.1 (Coster) and 2712 (Coster). These values are all in good agreement (within less than 1 x-unit) with the positions of Coster's white lines. (3) In the case of compounds of higher valence, the white line Coster obtained is therefore due to reduced element. (4) In the case of sulfides and sulfites, the secondary absorption edge at 4988 x-units reported by ${\mathrm{Lindh}}^3$ may likewise be due to traces of sulfate in the screen produced by the action of the x-rays.