Crossed supersonic beam measurements of the Penning ionization electron spectrum for the title system are reported for a collision energy range E=1.6 to 7.4 kcal/mol. The spectra are deconvoluted to obtain separate line shapes for the four possible combinations of J(Ne) and J(')(Ar+). The reagent fine structure ionization cross-section ratio Q(J=0)/Q(J=2) is found to increase from 1.1 to 1.5 over this energy range, in good agreement with other studies. The anomalous product branching ratios Q(J,J)(')=3/2/Q(J,J)(')=1/2 found by Hotop [J. Electron Spectrosc. Relat. Phenom. 23, 347 (1981)] are reproduced; these also depend weakly on E. The width and blueshift of all lines increase with E, while line shape asymmetry increases rapidly at low E and levels off at high. Comparison is made with quantum-mechanical calculations based on previously proposed potentials; the calculations predict oscillatory E dependence of the linewidth and asymmetry. (C) 2003 American Institute of Physics.