Attosecond-Scale Charge Migration Studies using a Water-Window X-ray Source Chase E. Geiger, Quynh V. Le, Zenghu Chang, W. T. Hill III

Charge migration is an electronic ultrafast process – unlike charge transfer which involves a slower redistribution of electrons and nuclei – and requires tools with sub-femtosecond temporal resolution to observe. This research involves the use of a broadband, Carrier Envelope Phase (CEP)-stable, femtosecond pulsed 1.7-micron infrared source to generate attosecond pulses through High Harmonic Generation (HHG) in a target gas. These X-ray attosecond pulses have sufficient photon energy (284-543 eV) to perform studies at the Carbon and Nitrogen K-edge, and have been used to probe vibrational, rotational, and electronic dynamics in atoms, molecules, and condensed matter on attosecond, femtosecond, and picosecond timescales. It is planned to use the 1.7-micron Optical Parametric Chirped Pulse Amplifier (OPCPA) as the driving laser for the X-ray source in an attosecond transient absorption spectroscopy (ATAS) setup to observe electronic and nuclear motion during photoinduced charge migration in propiolic acid molecules. This study will provide valuable information about the coupling between electrons and nuclei.