EN
We have performed photoluminescence measurements in order to study the optical properties of hydrogenated GaAs_{1-y}N_y/GaAs heterostructures for y ranging from 0 to 0.03. Hydrogen irradiation leads to: (i) a progressive passivation of N-related recombination lines for low N content (y≈ 0.001); (ii) a sizable blue shift of the band gap in the "alloy" limit (y≈0.01). Thermal annealing restores the optical properties samples had before hydrogenation. These results can be accounted for by the formation of N^- -H^+ complexes and demonstrate that hydrogen irradiation provides a powerful tool for the analysis of photoluminescence spectra of GaAs_{1-y}N_y.