Steady-state abundances (with respect to H nuclei) of nitrogen hydrides as a function of O/P, in a 10 K gas with n_H = 10⁴ cm^-3, and ζ = 1.3    ×    10^-17 s^-1. The rate of reaction (1) is given by Eq. (3). Two branching ratios for the channel N₂H ⁺  + e ⁻  → NH + N are considered: 0% (dashed lines) and 10% (full lines). The observed abundances from Paper I are also indicated (filled rectangles).