Mode-selective decay dynamics of the ortho-H2—OH complex: experiment and theory

Abstract

The predissociation dynamics of ortho-H2—OH in its ground electronic state are studied in time-resolved experiments and quantum mechanical calculations. The experiments use stimulated Raman and infrared overtone pumping to excite the νH2 = 1 or νOH = 2 vibrational states of the complex. The appearance of the OH X 2Π products is monitored as a function of time. Vibrational predissociation lifetimes and rotational product distributions are calculated in full dimensionality with a time-dependent wavepacket technique using a potential energy surface derived from high quality ab initio calculations. Both experiment and theory give predissociation lifetimes for νH2 = 1 that are an order of magnitude shorter than those for νOH = 2, and only a small number of OH rotational product states are found to be populated. The possibility of inducing chemical reaction via initial vibrational excitation of H2—OH is discussed.