In this work we study in detail the Ne VII $2s3p-2s3s$ singlet line, which was also the object of a recent experiment. The standard perturbative impact theory predictions are tested against a fully nonperturbative semiclassical impact calculation, taking into account dipole and quadrupole interactions. Potentially very significant problems with the standard perturbative theory are encountered and discussed, and a simple remedy is proposed.

• Received 17 March 1995

DOI:https://doi.org/10.1103/PhysRevLett.75.3406