Strong system–bath interactions and the control of the photodissociation of CH3I

Abstract

We present a time-dependent theory of system–bath interactions resulting in a reduced set of readily solvable integro-differential equations for the exact description of the multi-level system dynamics. We apply the method to the strong-field laser-induced dynamics of bound states interacting with multiple electronic states and multiple nuclear continua, and in particular to the bichromatic control of the photodissociation of methyl iodide, CH3 + I*(2P1/2) ← CH3I → CH3 + I(2P3/2). We have computed the complete strong-field control-map ‘landscapes’, depicting the yield of the I(2P3/2) ground atomic state as a function of external laser parameters. Employing pulses of 50–75 fs durations and 10–100 TW cm−2 intensities, we find yields which range between ∼10% and ∼45%, as compared to the natural value of ∼30%. These values should be contrasted with the weak-field control case where the yields vary over the much larger range of ∼0–80%, though with a much lower total dissociation yield per pulse. In addition to the above, we demonstrate the validity of the Markov approximation for strong laser-mediated system–bath interactions involving ‘slowly varying’ continua.