Optical emission in the dissociation of ammonia by low energy He+ ions Ryszard Drozdowski, Slawomir Werbowy, Łukasz M. Sobolewski and Andrzej Kowalski Eur. Phys. J. D, 71 3 (2017) 76 Published online: 28 March 2017 DOI: 10.1140/epjd/e2017-70732-7