Ultrafast dynamics in core-excited states probed by resonant Auger spectroscopy: pyrrole

We present high-resolution resonant Auger spectra of pyrrole at both the nitrogen and carbon edges. Through comparison to high-level quantum chemical calculations and a linear vibronic coupling model, we show how resonant Auger spectroscopy can capture the out-of-plane nuclear motions that occur during the few femtosecond core-hole relaxation processes. We also demonstrate how, in scenarios where there are near-degenerate electronic transitions in the X-ray absorption spectrum that cannot be resolved experimentally, resonant Auger can be used as a probe of the underlying electronic structure. Overall, resonant Auger is a technique capable of revealing detailed information about core-excited molecules that cannot be recovered through X-ray absorption or photoelectron spectroscopy alone.