Photo-dissociation of CD₄⁺: D₂ vs 2D elimination

Fragmentation of singly- or doubly-charged hydrocarbon molecules is dominated by H-elimination. It is challenging to distinguish experimentally between H₂-elimination and the competing 2H-elimination, as the later involves the detection of neutral particles with small relative momentum. We investigate the photo-dissociation of CD₄⁺ by intense ultrashort laser pulses and focus on the competition between D₂-elimination (CD₂⁺ + D₂) and 2D-elimination (CD₂⁺ + D + D). A coincidence three-dimensional momentum imaging measurement of a fast (keV) CD₄⁺ beam is used to identify both channels above. For the CD₂⁺ + D + D channel, we evaluate the Newton sphere diameter of 2D’s at the detector, using the Native frame analysis technique, to determine the detection limitation. Interestingly, data suggests that D₂-elimination is more likely than 2D-elimination.