The recoil energies of up to several MeV developed during nuclear reactions involving particle emission lead to the radionuclides
used in the analysis being redistributed between adjacent materials. In aluminum irradiated by reactor neutrons,24Na losses were observed up to a depth of 8·10−6 m; in the adjacent silicon, a24Na penetration depth was observed up to 4·10−6 m. Similar results were obtained from reaction products deriving from irradiation of Ti, Ni, N, S and Cl. This means that
the results of activation analysis investigations performed for the purpose of evaluating this type of reaction might contain
significant errors if thin layers, boundary zones of very small sample volumes are examined. In the analysis of surface layers
on silicon devices, completely erroneous results have been obtained in some cases due to the recoil phenomena described.