Strong Field Probes of Ultrafast Molecular Dynamics: Dissociation of NO$_{2}$

Strong laser-field based methods such as high-harmonic generation and strong field ionization (SFI) are considered novel probes of ultrafast excited state molecular dynamics. We present an experimental femtosecond time-resolved SFI study of the excited state dynamics of NO$_{2}$ using channel-resolved above-threshold ionization (CRATI) as the probe technique. CRATI makes use of PhotoElectron-PhotoIon COincidence (PEPICO) spectroscopy to study correlations in fragmentation dynamics in molecular systems. The use of PEPICO and covariance methods allows us to correlate ATI photoelectrons associated with a particular ionic fragment and, hence, SFI electron orbital ionization channel. In all ionization channels considered, we observed variations in the ion and photoelectron yields as a function of pump-probe delay as well as the observation of persistent ATI combs at long time delays. In disentangling the excited state dynamics of NO$_{2}$, we examine the complex roles of one-photon excitation, multiphoton excitation to higher lying excited neutral states, non-adiabatic excited state dynamics and several neutral and ionic dissociation channels.