Quantum Control of Molecular Photodissociation Reactions with Intense Laser Fields

Quantum control of molecular reaction dynamics has been a challenging subject of research for many years. Here, a new control scheme is proposed to modify the fragment distributions of molecular photodissociation reactions. The scheme is applied to the A-band photolysis of CH3I, which is simulated using a realistic wave packet model. The control scheme applies a single moderately intense (1010–1013 W cm–2) pump pulse to excite CH3I. This pulse produces light-induced conical intersections (LICIs) between the ground and excited electronic states, that reshape the natural diabatic potentials, generating new adiabatic light-induced potentials (LIPs). The new LIPs lead to different photodissociation dynamics, producing different fragment distributions compared to the weak-field regime. Complete inversion of the branching ratio I*(2P1/2)/I(2P3/2) between the two dissociation channels is achieved, with the previously dominant I*(2P1/2) channel practically suppressed, and the minor I(2P3/2) channel becoming the dominant one. Experimental implementation of the scheme appears straightforward and of universal application to photodissociation processes.