Vibrational predissociation of the ethylene dimer

Abstract

The energies, lifetimes and product state distributions for vibrational predissociation of the van der Waals complex (C₂H₄)₂ have been calculated. A coupled channel method, which includes both vibration and azimuthal rotation of the ethylene monomers, has been used. Lifetimes are found to be of the order of 10^–6 s, which supports the recent observation by Snels et al. that fine structure exists within the infrared photodissociation spectrum. A curve-crossing mechanism propsed by Ewing is also investigated but cannot account for lifetimes on the picosecond timescale.