Chemical Physics Seminar: Multidimensional High Harmonic Spectroscopy of Polyatomic Molecules

Abstract:

High harmonic generation (HHG) spectroscopy has opened up a new frontier in ultrafast science, where electronic dynamics can be measured on an attosecond time scale. The strong laser field that triggers the high harmonic response also opens multiple quantum pathways for multielectron dynamics in molecules, resulting in a complex process of electron rearrangement during ionization.  This dynamical information is encoded in the HHG spectrum in principle, but extracting it is extremely challenging in practice.  New experimental and theoretical approaches are essential to maximize the potential of HHG spectroscopy.  We show how a form of multi-dimensional HHG spectroscopy can be used to detect and follow electronic dynamics of core rearrangement on sub-laser cycle time scales. These dynamics leave a clear fingerprint in multidimensional HHG spectra, from which we can reconstruct the relative phases and amplitudes for relevant ionization channels in a CO2 molecule on a sub-cycle time scale. Our study brings us one step closer to developing robust schemes for sub-femtosecond imaging of multielectron dynamics in complex molecular systems.