N-14/N-15 isotope fractionation in the reaction N2H/+/ + N2 - Interstellar significance

The forward and reverse rate coefficients have been determined at 80 and 292 K for the reactions: (N-14)2H(+) + (N-14)(N-15) reversibly yields (N-14)(N-15)H(+) + (N-14)2; (N-14)(N-15)H(+) + (N-15)2 reversibly yields (N-15)2H(+) + (N-14)(N-15); and (N-14)2H(+) + (N-15)2 reversibly yields (N-15)2H(+) + (N-14)2. At 80 K, there are measurable differences between the forward and reverse rate coefficients for all three reactions, and so approximate values for the reaction ergicities have been obtained. The data for the first reaction are considered in relation to fractionation of (N-15) into N2H(+) in interstellar clouds, and it is argued that this phenomenon could enhance (N-15) in N2H(+) by about a factor of 2 above that in N2, the assumed reservoir of nitrogen in these media.