Steering the outcome of a photochemical reaction-An in silico experiment on the HCSO sulfine using few-femtosecond dump pulses.

We propose a pump-dump control scheme using sub-10 fs pulses to enhance the photochemical formation of the three-membered C-S-O ring oxathiirane from the parent HCSO sulfine molecule. The ultrashort nature of the pulses is essential to promptly alter the photoinduced dynamics, e.g., while a bond is elongating, which is key to selectively form the oxathiirane by radiative dumping. We carried out an in silico pump-dump experiment with excited-state dynamics simulations that include the interaction with electric field of the pump and dump pulses. By applying the dump pulse when the CS bond is elongating, the population transferred to the ground state will form the oxathiirane with a branching ratio of 4, much higher than the one solely due to nonradiative relaxation (0.66). The overall oxathiirane yield can be increased by up to 17% when the 6 fs IR dump pulse is applied at a delay time of 47 fs.