Dissociative recombination measurements of NH${}^{+}$ using an ion storage ring

Abstract

We have investigated dissociative recombination (DR) of NH${}^{+}$ with electrons using a merged beams configuration at the TSR heavy-ion storage ring located at the Max Planck Institute for Nuclear Physics in Heidelberg, Germany. We present our measured absolute merged beams recombination rate coefficient for collision energies from 0 to 12 eV. From these data we have extracted a cross section which we have transformed to a plasma rate coefficient for the collisional plasma temperature range from $T_{\mathrm{pl}}=10$ to $18000$ K. We show that the NH${}^{+}$ DR rate coefficient data in current astrochemical models are underestimated by up to a factor of $\sim 9$. Our new data will result in predicted NH${}^{+}$ abundances lower than calculated by present models. This is in agreement with the sensitivity limits of all observations attempting to detect NH${}^{+}$ in interstellar clouds.

arXiv commentJuly 1st 2014: Accepted for publication in ApJ

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