Ultrafast dynamics of the Rydberg states of CO2: Autoionization and dissociation lifetimes

We report the measurement of ultrafast relaxation dynamics of excited states of the carbon dioxide molecule using time-resolved pump-probe photoelectron spectroscopy. Neutral ground-state carbon dioxide is excited to ndsσ_g Henning sharp Rydberg states with an attosecond extreme ultraviolet pulse train. A time-delayed near-infrared probe pulse is used to photoionize these states to their corresponding ionization limit B2ςu+. We obtain differential kinetic energy spectrograms and angular distributions for photoionization and autoionization channels. We model the competition between predissociation and autoionization in the Rydberg-state dynamics and analyze the differential photoelectron yield as a function of the time delay to extract autoionization and predissociation lifetimes for three Henning sharp states n=4,5,6.