Multi-body fragmentation of polyatomic molecules following ionization by intense laser pulses

Intense laser pulses that multiply ionize polyatomic molecules often create unstable molecular ions that can fragment in complex ways. Coincidence momentum imaging of the ionic products reveals the fragmentation dynamics, including whether the process is concerted or sequential. These processes are distinguished using the native frames analysis method. For example, in both formic acid (HCOOD³⁺ → D⁺ + O⁺ + HCO⁺) and ethanol (CH₃CH₂OH²⁺ → H₃⁺ + C₂H₂O⁺ + H), different sequential processes lead to the same final products. We identified several examples of hydrogen elimination as the first fragmentation step, such as eliminating both hydrogen atoms from HCOOD²⁺, forming a long-lived CO₂²⁺ intermediate. In other cases, however, we find that eliminating a neutral is the final step stabilizing the intermediate ion, e.g. CH₃CH₂OH²⁺ → H₃⁺ + CH₃⁺ + CO.