Near-threshold electron impact excitation of the argon 3p54s configuration--new and revised normalized differential cross sections using recent time-of-flight measurements for normalization

Revised electron impact differential cross section (DCS) for excitation of the four levels comprising the 3p54s configuration of argon and their sum are reported for incident electron energies of 12.5, 13.0, 14.0, 14.5, 15.0, 15.5, 15.76, 16.0, 16.75, 17.5 and 20 eV. These cross sections were obtained using two conventional high-resolution electron spectrometers, but normalized where possible to recent inelastic-to-elastic scattering DCS ratios of the time-of-flight (TOF) measurements by Mondal et al (2009 PMC Phys. B 2 3). We also present results from new calculations of these DCSs using the B-spline R-matrix method (Zatsarinny and Bartschat 2004 J. Phys. B: At. Mol. Opt. Phys. 37 4693). Comparisons with earlier experimental DCS results are made, and we provide correction factors for the argon DCS values of Khakoo et al (2004 J. Phys. B: At. Mol. Opt. Phys. 37 247), based on TOF measurements.