The interaction of high-energy protons and alpha particles with Ta, Au, and Bi to produce Tb149 was investigated by the recoil technique and by measuring the excitation functions. The experimental results were analyzed in terms of a two-step mechanism: (1) An initial interaction causes the struck nucleus to recoil forward. (2) This excited nucleus then loses its energy of excitation by emitting various particles until the final nucleus is formed. The results of this analysis confirm the main features of this mechanism. These results were further analyzed for the details of the mechanism by applying the laws of energy and momentum conservation in a general way.