2014 Articles

Dissociative recombination measurements of NH+ using an ion storage ring

Novotny, Oldrich; Berg, M.; Bing, D.; Buhr, H.; Geppert, W.; Grieser, M.; Grussie, F.; Krantz, C.; Mendes, M.; Nordhorn, C.; Repnow, R.; Schwalm, D.; Yang, B.; Wolf, A.; Savin, Daniel Wolf

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 pl = 10 to 18,000 K. We show that the NH+ DR rate coefficient data in current astrochemical models are underestimated by up to a factor of approximately nine. Our new data will result in predicted NH+ abundances lower than those calculated by present models. This is in agreement with the sensitivity limits of all observations attempting to detect NH+ in interstellar clouds.