Elucidating isotopic effects in intense ultrafast laser-driven D2H+ fragmentation

The triatomic hydrogen molecular ion is instrumental as a benchmark towards understanding the strong-field dynamics of polyatomic molecules. Using a crossed-beams coincidence three-dimensional momentum imaging method, we demonstrate clear isotopic effects in the fragmentation of D2H+ induced by 7 fs (40 fs), 790 nm laser pulses at an intensity of 1016 W cm−2 (5 × 1015 W cm−2). Our experiment uniquely separates all fragmentation channels and provides kinematically complete information for the nuclear fragments. For example, we show that for dissociative ionization of D2H+ there is a large difference in branching ratios of the two-body channels, namely, H++D2+ dominates D++HD+, whereas there is minimal difference in branching ratios between the dissociation channels H++D2 and D++HD. (fast track communications)