The Absorption Coefficients of Homogeneous X-rays between Wave-Lengths 0.1 A and 0.71 A

Abstract

Using the general radiation from a tungsten target, dispersed by reflection from a crystal, the total mass absorption in fourteen elements of atomic number 6 to 83 (C, Mg, Al, S, Fe, Ni, Zn, Ag, Sn, W, Pt, Au, Pb and Bi) was determined for various wave-lengths from.10 A to.51 A by the ordinary ionization measurements. The $\mathrm{K}\ensuremath{\alpha}$ and $\mathrm{K}\ensuremath{\beta}$ radiation from a Mo target was used to give values for wave-lengths.63 A and.71 A. Very good agreement was found with the results of Richtmyer and Duane wherever these are comparable. For the elements from C(6) to W(74) the results are represented within a few per cent by the formula $\frac{\ensuremath{\mu}}{\ensuremath{\rho}}=\frac{\ensuremath{\tau}}{\ensuremath{\rho}}+\frac{\ensuremath{\sigma}}{\ensuremath{\rho}}=C{\ensuremath{\lambda}}^{2}^{92}N^{2.92}+\frac{\ensuremath{\sigma}}{\ensuremath{\rho}}$, where $C=7.82{(10)}^{\ensuremath{-}3}$ for the K absorption and 1.00${(10)}^{\ensuremath{-}3}$ for the L absorption and the scattering coefficient $\frac{\ensuremath{\sigma}}{\ensuremath{\rho}}$ is assumed to increase with $N$ from.144 for Al to.50 for W at.12 A, and also with the wave-length. The jump in the value of the fluorescent absorption coefficient $\frac{\ensuremath{\tau}}{\ensuremath{\rho}}$ from L to K absorption is the ratio of ${C}_{K} \mathrm{to} {C}_{L}$ or 7.8. The atomic absorption ${\ensuremath{\tau}}_{a}=2.18{(10)}^{\ensuremath{-}26}{\ensuremath{\lambda}}^{2.92}{N}^{4}$ (Bragg-Owens law). For the heavier elements Pt, Au, Pb and Bi the values of ${C}_{K}$ get progressively lower to 4.7 ${(10)}^{\ensuremath{-}3}$ and those of ${C}_{L}$ increasingly higher to 1.12 ${(10)}^{\ensuremath{-}3}$, the ratio or jump decreasing to 4.1 for Bi.