Photodissociation dynamics of I3- using femtosecond photoelectron spectroscopy

The photodissociation dynamics of gas phase I-3(-) following 390 nm excitation are studied with femtosecond photoelectron spectroscopy. Both I- and I-2(-) photofragments are observed; the I-2(-) exhibits coherent oscillations with a frequency corresponding to an average vibrational level[upsilon]=67. The oscillations dephase by 4 ps and rephase by similar to 45 ps. This can be understood by considering the dynamics of a coherent superposition of vibrational stales on the anharmonic I-2(-) potential. Our results represent the first example of coherently produced photodissocation products undergoing dynamical rephasing. Also for the first time the gas phase frequency of ground state I-3(-) is determined via a resonance impulsive stimulated Raman scattering process. Finally, the photoelectron spectrum of I-3(-) yields the vertical detachment energy of I-3(-) and the spacing between the first two electronic states of the neutral I-3(-) molecule. The photodissociation dynamics of gas phase I-3(-) differ considerably from those observed in condensed phase experiments.