David Storm

On the Relation between Symmetric and Asymmetric Charge Exchange

A theoretical calculation was made of the cross sections for the processes: Li++Li→Li+Li+, Li++Na→Li+Na+, using hydrogenic 2s traveling orbitals in a two‐state approximation. It was found that the general outline of the results found by Rapp and Francis, using a very crude approximate model, remain unchanged in this more rigorous calculation. The main difference between the present results and those of Rapp and Francis is that the cross sections fall off more rapidly at velocities above 5 × 107 cm/sec when traveling orbitals are used. It may be concluded that nonresonant charge transfer does indeed behave like symmetric resonant charge transfer at velocities above that necessary to satisfy the adiabatic criterion υ = ΔEa / h.

ONE-ELECTRON MODEL FOR CHARGE EXCHANGE IN ION--ATOM COLLISIONS.

In attempting to calculate cross sections for charge exchange in other than proton‐hydrogen atom collisions, it has been common to simplify the system by assuming that only one active electron is moving in the field of two ions. With this one‐electron approximation, the extensive formalism developed to treat proton‐hydrogen atom collisions has then been applied. It is shown that the use of some common one‐electron orbitals in such a formalism can destroy either the ability to interpret the expansion coefficients as transition amplitudes, or probability conservation. In this work, a one‐electron model Hamiltonian and corresponding expansion functions are proposed by which the physical system is more accurately described. With this model it is shown that physically acceptable transition amplitudes can be calculated, probability is conserved, and the principle of microreversibility is satisfied.