Theory of ultrafast laser control of isomerization reactions in an environment: Picosecond cope rearrangement of substituted semibullvalenes

An efficient approach to control isomerization reactions by ultrashort infrared laser pulses in the presence of a thermal environment is developed and demonstrated by means of model simulations within the reduced density matrix formalism beyond a Markov-type approximation for a picosecond Cope rearrangement of 2,6-dicyanoethyl-methylsemibullvalene coupled to a quasi-resonant environment. The population transfer from the reactant state via the delocalized transition state to the product state is accomplished by two picosecond infrared laser pulses with a probability up to 80% despite the rather strong coupling to the environment, which reduces the lifetime of the transition state into the femtosecond time domain. Simulations, carried out for helium (4 K), nitrogen (77.2 K) and room (300 K) temperatures, show that low temperatures are preferable for state-selective laser control of isomerization reactions.