A new upper limit to the vibrational predissociation lifetime of ethylene dimer excited at 950 cm−1

A direct measurement in the time domain has been performed of ethylene dimer population decay following single-quantum excitation of the ν7 monomer vibrational mode. Nonresonant multiphoton ionization at 355 nm was used to probe the dimer population as a function of time following excitation with a pulsed CO2 laser. The measured signal decay was found to be determined by the experimental time resolution function, implying that the predissociation lifetime of the dimer is less than about 10 ns.