Tracking dynamic wave packets in the O$_{2}$ dication using a pump/probe approach*

Vibrational wave packet dynamics in the O$_{2}$ dication have been tracked with few-cycle near-infrared laser pulses. Bound and dissociating wave packets were launched and subsequently probed via a pair of 8 fs pulses at 800 nm. Ionic fragments from the dissociating molecules were monitored using a velocity-map imaging apparatus. Pronounced oscillations in both the time-dependent kinetic energy release spectra and in the time-dependent fragment yields were observed. Facilitated by the observation of vibrational revivals, the dynamics of the wave packets on specific potential energy curves of the O$_{2}$ dication are discerned. Quantum and semi-classical calculations are in good agreement with the measured dynamics.