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The absorption factor of a powder usually assumes a homogeneous material distribution with a locally independent absorption coefficient  αμ ,  α : relative mass density. To correct for the influence of inhomogenity, a semiempirical correction factor  κ  has been developed in several steps. First a general approximation formula for  κ  has been derived. On the basis of the  κ -formula found, a computer program has been established for a 2-dimensional powder model. It represents the grains by circles of diameters equal to the mean grain diameter [unk] and is useful to an upper limit  ϑ G   of the Bragg-angle, where the correction is due to the absorption in exactly the volume of a single grain. Comparison of experimental  P ( ϑ )-curves of Suortti (1972) –  P ( ϑ ) = 1 −  κ ( ϑ ) – with corresponding model curves in the range  ϑ  [unk]  ϑ G   showed qualitative, and in some respects quantitative agreement. Therefore  P ( ϑ )-formulas were sought, on one side giving good agreement with Suortti's experimental  P ( ϑ )-curves, on the other reflecting the theoretical outline made before. The result is: For  ϑ G  , given by tg ϑ G   = [unk], we have  P ( ϑ G  ) =  μ g[unk] −  αμ [unk]/sin  ϑ G  ,  g  = 0.83 ± 0.01. Theoretically  g [unk] means the mean absorption path in a single grain, which in our model we have  g  = 8/(3 π ) = 0.85. For  ϑ  &lt;  ϑ G   we obtain  P ( ϑ ) =  P ( ϑ G  ){1 + 0.5( μ [unk] +  α )[( ϑ G   −  ϑ )/ ϑ G   − 10°)] 3 }.

Korrektur des Absorptionsfaktors für eine ebene, undurchlässige Pulverplatte und zum symmetrischen Braggfall analogen Strahlengang