Selective photodissociation of O–H and O–D bonds from ground vibrational state of HOD using simple UV pulses

Abstract

Selective cleaving of both O–H and O–D bonds in HOD is achieved using reasonably simple UV pulses to excite the HOD molecule in its ground vibrational state to the repulsive first excited  (¹B₁) surface. Detailed theoretical analysis of population transfer and flux in the H+O–D∕H–O+D channels reveals an important preparatory role for the cross-talk between the participating levels and a possible role for the beat structure of the population transfer oscillations in facilitating selective dissociation. Excitation using a 50 fs single color 67169 cm⁻¹ laserpulse achieves a branching ratio H+O–D∕H–O+D=5.64 with 82% flux in theH+O–D channel and 15% in the H–O+D channel. A two color 50fs laser pulse with frequencies of 54 920 and 52303 cm^-1 provides a branching ratio of H–O+D∕H+O–D=2.83 and 52% flux in the H–O+D channel and 18% in the H+O–D channel.