Quantum non-adiabatic dynamics through conical intersections: spectroscopy to reactive scattering

Some of the recent developments in the quantum dynamical studies at the conical intersections of molecular potential energy surfaces is briefly reviewed in this article. Particular emphasis is given to a variety of molecular processes studied by us in the recent past. The non-adiabatic effects due both to the electronic as well as relativistic spin–orbit coupling are considered. The discussions include the Jahn–Teller effect (and also the pseudo-Jahn–Teller effect whenever applicable) in the Rydberg emission spectrum of triatomic hydrogen and the photoelectron spectrum of cyclopropane and methyl fluoride, probing the conical intersections in ClO<SUB>2</SUB> and the reagent van der Waals well in the Cl(<SUP>2</SUP>P)+H<SUB>2</SUB> reaction via the photodetachment spectroscopy of the negative ions, ClO<SUP>-</SUP><SUB>2</SUB> and ClH<SUP>-</SUP><SUB>2</SUB>, respectively, and the thermal scattering dynamics of H+H<SUB>2</SUB> and Cl(<SUP>2</SUP>P)+H<SUB>2</SUB> reactions on multisheeted potential energy surfaces