Measuring Attosecond Photonionization Delays in N₂O

Photoionization delays are a tool to probe complex electronic interactions in atoms and molecules. The ionization delay of core level electrons in atoms and molecules can be especially sensitive to many-body electronic processes. In this work, we measure the photoionization delay near the oxygen K-edge in N₂O via angular streaking at the LCLS using attosecond x-ray pulses. We observe a delay that cannot be explained by just the atomic potential of the molecule and assign this unusually large delay to the oxygen shape resonance. We calculate the photonionization delay and compare these calculations to our measurement.