Light-Field Dressing of Transient Photoexcited States above the Fermi Energy

Time-periodic light field provides an emerging pathway for dynamically engineering quantum materials by forming hybrid states between photons and Bloch electrons. So far, experimental progress on light-field dressed states has been mainly focused on the occupied states; however, it is unclear if the transient photoexcited states above the Fermi energy E_{F} can also be dressed, leaving the dynamical interplay between photoexcitation and light-field dressing elusive. Here, we provide direct experimental evidence for light-field dressing of the transient photoexcited surface states above E_{F}, which exhibits distinct dynamics with a delay response as compared to light-field dressed states below E_{F}. Our work reveals the dual roles of the pump pulse in both photoexcitation and light-field dressing, providing a more comprehensive picture with new insights on the light-induced manipulation of transient electronic states.