Formation of hydrogen atoms in arbitrary excited states by electron capture in p-H collisions

A new technique for the evaluation of the exchange amplitude for the process H+ + H(1s) → H(nlm) + H+ in the Born approximation taking the full interaction into consideration has been presented. This technique is also applied to two other first-order approximations which aim an improvement over the Born approximation by taking account of the lack of orthogonality of the initial-and final-state wavefunctions. It is found that, over a wide range of incident proton energies, the cross sections for electron capture into different angular momentum states of an excited state having a moderate or high value of the principal quantum number are related to the respective asymptotic cross sections by a simple scaling law. The results in the various approximations discussed have been compared with experimental data. (author)