Probing Electron Correlation in Molecular Photoionization with Attosecond Interferometry

Understanding the role of interchannel coupling and correlated electron motion in atomic and molecular systems remains an outstanding problem in chemistry and physics. Measurements of the phase of the photoionization dipole matrix element of helium, neon, and carbon dioxide were performed at the Low Density Matter beamline at FERMI using an attosecond interferometry technique exploiting a train of harmonic pulses dressed by a 266 nm field. Photon energy dependence of this phase was analyzed with a novel correlation-based analysis that allows for investigation into time dynamics such as shape resonances and autoionizing states. Comparison of the intercycle and intracycle phase differences of neon at different photon energies has allowed for direct probing of the continuum structure as well as inherent structure in the attosecond pulse train. Furthermore, phase offsets between the different ionic states of CO2 help clarify the cause of the long-standing discrepancy between experiment and theory surrounding the C-state shape resonance in CO2.