Role of photolysis frequency in enhanced selectivity and yield for controlled bond breaking in HOD

Abstract

Quantum dynamical calculations on HOD subjected to different combinations of IR and UV pulses have been made to isolate field attributes which maximize selectivity and yield in the photodissociation of the desired O-H/O-D bond. Results from IR/UV pulse combinations which provide very high selectivity and/or yield are analyzed in detail by using population transfer, probability density flow, and flux variations to obtain microdynamic details favoring selectivity and yield. Results indicate that a 2727 cm^-1 50 fs Gaussian IR pulse in conjunction with a 46062 cm^-1 50 fs Gaussian UV pulse with a time lag of ~90 fs between the IR and UV pulses gives 79.1% flux in the H-O + D channel and 6.6% flux in the H + O-D channel, whereas a 3706 cm^-1 50 fs IR pulse in conjunction with a 51090 cm^-1 UV pulse gives 9.2% flux in the H-O + D channel and 82.1% flux in the H + O-D channel. A 2727 cm^-1 50 fs IR pulse in conjunction with a 40062 cm^-1 50 fs UV pulse provides the greatest selectivity among the sampled field profiles with a flux branching ratio of H-O + D/H + O-D ≈ 487.8, and a 3706 cm^-1 50 fs IR pulse in conjunction with a 45090 cm^-1 50 fs UV pulse achieves a flux branching ratio of H + O-D/H-O + D ≈ 1354.8.