Abstract
The differential capture amplitude for charge exchange from the hydrogenic ground state (1s) to an arbitrary final state (nlm) of hydrogen is calculated within the Coulomb-Brinkman-Kramers approximation in closed form. The result serves to determine orientation, alignment and s-p coherence as a function of the scattering angle theta . Applications to electron capture from the K shell of argon by fast protons and alpha particles are discussed. Coherences between substates provide a sensitive test for the validity of the semiclassical approximation.