Ji-Cai Liu, Nicolas Velasquez, Victor Kimberg, Sayantan Sarkar, Oksana Travnikova, Iyas Ismail, Renaud Guillemin, Man Zhang, Pavel Krasnov, Marcella Iannuzzi, Michael Odelius, Ralph Püttner, Maria Novella Piancastelli, Marc Simon, Faris Gel'mukhanov, Tatiana Marchenko
Ultrafast charge transfer (CT) lies at the heart of molecular and electronic functionality. We develop a Fano-based core-hole clock (FCHC) method that captures coherent coupling between localized excitons and the directly populated delocalized CT continua in resonant Auger scattering. Applied to sulfur KLL Auger spectra of a conductive organic polymer, FCHC reveals clear Fano interference and a CT time of 27±1.8 fs, demonstrating that the conventional core-hole clock model underestimates the CT dynamics timescale. We establish FCHC as a robust method for probing ultrafast CT in complex molecular systems.