[en] The optical emission of N₂⁺(B²Σ⁺sub(u)→X²Σ⁺sub(g)) induced by energy transfer (Penning ionization) to nitrogen from 2³S metastable helium atoms (He*) has been measured by pulse radiolysis of helium-nitrogen mixtures. The emission decay rate tau^-1 varies as a function of helium or nitrogen pressure, which gives a Penning ionization rate constant k₂(He*+N₂) = (6.8+-0.4)x10^-11cm³ molecule^-1s^-1. (Auth.)