Experimental small-angle electron differential cross sections (DCS’s) for the resonance transition in Na at 10, 20, and 54.4 eV are contrasted through the generalized oscillator strength (GOS) and with the GOS from a recent universal extrapolation function [A. Z. Msezane and I. A. Sakmar, Phys. Rev. A 49, 2405 (1994)]. We conclude that almost all of the measurements reported suffer from an incorrect determination of the DCS near-zero scattering angles and/or from an improper normalization. Dynamic effects are unimportant at 20 and 54.4 eV at small scattering angles.

• Received 11 July 1994

DOI:https://doi.org/10.1103/PhysRevA.50.3905