Attosecond Spectroscopy Enables Observation of Ultrafast Atomic, Optical Phenomena . BERLIN, June 15, 2022 — Researchers from the Max Born Institute, University College London, and ELI-ALPS in Szeged, Hungary, demonstrated attosecond-pump attosecond- probespectroscopy . Demonstrat ion of the technique allowed the collaborators to study nonlinear multiphoton ionization of atoms. Femtosecond pump-probe spectroscopy has been instrumental to understanding extremely ...