The K-shell fluorescence yield and atomic shell structure effects

Calculations of the Auger and radiative transition rates from the K shell over the whole range of periodic table have been assembled and extended where necessary in order to derive a set of predicted values of the K-shell fluorescence yield omega k . The results are compared with a set of best experimental values of omega k established by polynomial fitting to the experimental data. It is shown that both sets of data may be accurately represented by a relation of the form omega k =(1+ alpha Z -m ) -1 , where alpha =(1.25+or-0.05)*10 -5 , m=3.41+or-0.01 theoretically and alpha =(1.16+or-0.07)*10 -5 , m=3.36+or-0.02 experimentally. Clear deviations from these simple relations are observed in both sets of data and it is shown that these deviations may be interpreted in terms of atomic shell-structure effects.