Experimental determination of the X-ray attenuation coefficient of In at 8.047 keV

An experimental value of μ/ρ_In = 235.3 cm² g⁻¹ for the In attenuation coefficient with a Cu Kα wavelength has been determined with an improved accuracy of ±1%, by measuring the X-ray beam absorption of an In film deposited on an aluminium foil in which the total In content was determined by weighing the sample. To avoid errors in the absorption measurements due to the non-uniform layer thickness, the absorption was mapped and averaged over the whole sample area. The μ/ρ_In value obtained is 2.6% lower than the values obtained from International Tables of Crystallography (Vol. IV, 1974, pp. 47–70) and 7% lower than a recent experimental value. The value determined is essentially in agreement with data calculated from recent theoretical models. The method proposed can be applied to several other materials that can be deposited as thin layers on a light absorber.