Ion-ion coincidence experiments with low extraction fields

The fragmentation of a polyatomic molecular dication has been investigated by means of a Monte Carlo simulation which can take into account realistic experimental conditions. The simulation applied to the three body process CH42+ → CH2+ + H+ + H shows that the low angular acceptance, consequence of the low extraction field, does not prevent the distinction between the initial charge separation and the synchronous concerted decay mechanisms, which lead to the same final state. The comparison of the results with recent experiments [1] confirms that an initial charge separation with a following loss of a hydrogen atom describes better the experimental observations.