Symmetry-induced kinetic isotope effects in the dissociation dynamics of CHCl3 + and CHCl4 −

Loss of Cl from CHCl₃⁺ with little excess energy is found to proceed via two distinct pathways, the reaction channel which is being followed is determined by a symmetry-induced kinetic isotope effect. Computational investigations suggest competition between a statistical adiabatic process and a process of electronic predissociation. For CHCl₄⁻ and CH₂Cl₃⁻, rotational predissociation contributes to the kinetic isotope effects for all isotopomers, whereas the particularly large effect observed for CH³⁵Cl₃³⁷Cl⁻ also originates from symmetry-induced degeneracy of vibrational modes in the C_3V point.