Born cross sections have been calculated for electron-impact excitation of metastable levels of argon and krypton to higher-lying excited states. It is shown that the intermediate-coupling representation must be used to obtain reliable results. An approximate treatment of strong-coupling effects is included for the dominant $ns-np$ transitions, and the applicable range and validity of the Born calculations are considered.

• Received 7 April 1978

DOI:https://doi.org/10.1103/PhysRevA.18.441