A Reaction Accelerator: Mid-infrared Strong Field Dissociation Yields Mode-Selective Chemistry.

Mode-selective chemistry has been a dream of chemists since the advent of the laser in the 1970s. Despite intense effort, this goal has remained elusive due to efficient energy randomization in polyatomic molecules. Using ab initio molecular dynamics calculations, we show that the interaction of molecules with intense, ultrashort mid-infrared laser pulses can accelerate and promote reactions that are energetically and entropically disfavored, owing to efficient kinetic energy pumping into the corresponding vibrational mode(s) by the laser field. In a test case of formyl chloride ion photodissociation, the reactions are ultimately complete under field-free conditions within 500 fs after the laser pulse, which effectively overcomes competition from intramolecular vibrational energy redistribution (IVR). The approach is quite general and experimentally accessible using currently available technology.