[en] Absolute state-selected total cross sections σ/sub v//sub '/, v' = 0 and 1, for the reaction N⁺₂(X,v' = 0,1) +Ar(¹S₀)→N₂(X,v)+Ar⁺(²P/sub 3/2,1/2/) [reaction (1)] over the center-of-mass collisional energy (E/sub c.m./) range of 1.2--140 eV have been measured using the photoionization mass spectrometric and radio frequency ion guide methods. These measurements, together with the relative values for σ/sub v//sub '/, v' = 0--2, and spin-orbit-state distributions of product Ar⁺ ions determined using the crossed ion-neutral beam photoionization apparatus, allow the determination of the absolute values for σ₂ and partial state-to-state cross sections σ/sub v//sub '//sub →//sub J/, v' = 0--2, for reaction (1). Absolute values for σ/sub v//sub '/, v' = 0--2, at E/sub c.m./ = 8 and 20 eV are in good agreement with those determined previously by the threshold photoelectron secondary ion coincidence method. Absolute values for σ/sub v//sub '//sub →//sub J/, v' = 0--2, at E/sub c.m./ = 8 and 20 eV are also found to be in satisfactory accord with the predictions of the semiclassical multistate calculation which uses the ab initio potential energy surfaces of the [N₂+Ar]⁺ system