The investigation of the isotopic ratio of interstellar nitrogen -- 14N versus 15N -- is done, for explaining its variations observed for N2H+ in different interstellar and Solar environments. The goal is to produce cross sections and rate coefficients for electron impact dissociative recombination for different isotopologues of N2H+, since it was envisioned as a novel source that can lead to nitrogen fractionation. We calculate dissociative recombination cross sections and rate coefficients using the normal mode approximation combined with the R-matrix theory and vibronic frame transformation within the multichannel quantum defect theory for eight isotopologues containing both 14N, 15N and H, D. Our calculations show that the relative differences respective to the main isotopologue (14N2H+) is below 1% for the hydrogen containing isotopologues, but reaches almost 30% for the heaviest deuterated isotopologue, leading us to the conclusion that according to the present status of the theory, dissociative recombination is not responsible for the peculiar 14N/15N isotopic ratios of N2H+ observed in the different interstellar molecular clouds.
@article{arxiv.2501.18434,
title = {Dissociative recombination of N$_2$H$^+$: Isotopic effects},
author = {J. Zs. Mezei and A. Orban and S. Demes and M. Ayouz and A. Faure and P. Hily-Blant and Ioan F. Schneider},
journal= {arXiv preprint arXiv:2501.18434},
year = {2025}
}
Comments
7 pages, 8 figures, 2 tables. arXiv admin note: text overlap with arXiv:2305.17976