Raman time-delay in attosecond transient absorption of strong-field created Krypton vacancy

Abstract

Abstract One of the cornerstone for attosecond science is strong field ionization that injects a transient vacancy in the atom which is entangled to the outgoing photoelectron. When the electron is finally detached, the ions are left in a statistical population of different excited states with part of the coherence information lost. The preserved coherence of matter after interacting with intense short pulses has important consequences on the subsequent nonequilibrium evolution and energy relaxation. Here we employ attosecond chronoscopy to measure the time-delay of the resonant transitions of Krypton vacancy during their creation. It is observed that the absorptions by the two spin-orbit split states are modulated at different paces when varying the time delay between the near-infrared pumping pulse and the isolated attosecond probing pulse. It is shown that the coupling of the injected ions with the remaining field leads to a suppression of ionic coherence. The comparison between theory and experiments uncovers that the coherent Raman coupling between the two spin-orbit split states induces time-delay between the resonant absorptions, which provides new insight into laser-ion interactions enriching attosecond chronoscopy.