Ultrafast hydrogen migration in allene in intense laser fields: Evidence of two-body Coulomb explosion

Two-body Coulomb explosion of allene induced by an ultrashort (∼40 fs) intense laser field is investigated by the coincidence momentum imaging (CMI) method. From the CMI maps, two types of two-body Coulomb explosion pathways, C 3 H 4 2 + → CH m + + C 2 H 4 - m + (m = 1–3) and C 3 H 4 2 + → C 3 H 4 - n + + H n + (n = 1–3), are securely identified. The formation of CH 3 + , C 2 H 3 + , and H 3 + shows that the chemical bond rearrangement associated with the ultrafast hydrogen migration occurs prior to the ionization into C 3 H 4 2 + and that the extent of the hydrogen migration determines either one of the two initially identical CC chemical bonds is broken.