Exploring Ultrafast Molecular Dynamics using Photoelectron Spectra from UV/XUV Pump-Probe Experiments

The motion of atoms in molecules can drive electron dynamics via non-adiabatic couplings. In small molecules such as Ethylene, Carbon Dioxide, and Nitrophenol, this can lead to isomerization, electronic relaxation, or other time-dependent effects following excitation from a bonding to an anti-bonding molecular orbital. To study these mechanisms, we use ultraviolet photons of various energies from a bright High Harmonic Generation source to first initiate dynamics and subsequently probe the system through ionization. We record the kinetic energy and angular distribution of the resultant photoelectrons using a Velocity Map Imaging spectrometer, allowing us to track the evolution of the electronic state.