Energy and orientation independence of the channel branching in Ne* + ND3 chemi-ionisation.

Collisions of excited neon atoms with ammonia molecules can lead to two reaction processes, dissociative ionisation and Penning ionisation. Both processes result in the ionisation of the ammonia molecule and redistribution of the electronic energy into the internal ammonia ion rovibrational modes. We performed energy dependent, crossed-beam stereodynamics studies of the branching ratio between the two ionisation processes. It was found that the branching ratio is totally and completely insensitive to both the neon orientation and the collision energy across the range we sampled, 370-520 cm-1. The total lack of stereodynamics can be explained by the structure of the ammonia and that its orientation, which we do not attempt to control, is the critical factor in the reaction outcome.