Maxima and minima in the angular dependence of the [np)(n+1)s] transition in the rare gases observed by high-energy electron impact spectroscopy

A minimum and a maximum in the generalized oscillator strength are observed as a function of momentum transfer for the [$np\left)\right(n+1\mathrm{})s$] transition in Ne, Ar, Kr, and Xe using 25-keV incident electrons. The results indicate that the occurrence of these extrema is due to zeros in the first Born scattering amplitude, and the positions of the extrema are found to be in excellent agreement with available Hartree-Fock calculations.