HIGH-ENERGY BORN COLLISION STRENGTHS FOR OPTICALLY FORBIDDEN TRANSITIONS

Collision strengths for optically forbidden transitions in positive io ns excited by electron impact tend to finite limits as the energy of t he colliding electron becomes infinitely great. This statement applies to theoretical data obtained by means of approximations which ignore relativistic effects. The high-energy limiting values are given by the Born approximation, which Bethe showed can be reduced to a closed exp ression requiring integration over momentum transfer and the radial di stance of the atomic orbital. In the appendix we describe an accurate numerical procedure for evaluating this double integral and also show how to perform the Racah algebra which arises when mixed configuration s are used to describe the target. We make applications to several iso electronic sequences taking configuration interaction into account.