Measured reaction loss rates r_N⁺, r_NH⁺, , and of N⁺, NH⁺, NH, and NH ions, respectively, as a function of H₂ number density. The primary N⁺ ions are injected into the ion trap from the SIS. The collisional temperature is T = 18 K and helium number density is [He]=8 × 10¹³ cm⁻³. For the relatively slow reaction of NH ions, the plotted values of are multiplied by a factor of 2000. The corresponding binary reaction rate coefficients k_N⁺, k_NH⁺, , and given by the slope of the plotted dependences are indicated in the legend.