A modified pairwise-energy model applied to exothermic ion-molecule reactions

For an exothermic ion-molecule reaction A + BC → AB + C our modified pairwise-energy model shows that the reduced cross section Qred = [(mB + mC)/2mB]12QR depends only on ES, the pairwise energy between A and B. The four reactions of N2+ (and the four of Ar+) with H2, D2, and HD agree very well with this model, particularly for ES values above 0.7 eV.