Excited-state band structure mapping

Angle-resolved photoelectron spectroscopy is an extremely powerful probe of materials to access the occupied electronic structure with energy and momentum resolution. However, it remains blind those dynamic states above Fermi level that determine technologically relevant transport properties. In this work we extend band mapping into unoccupied across entire Brillouin zone by using a state-of-the-art high repetition rate, extreme ultraviolet femtosecond light source optically excited samples. The wide-ranging applicability power approach are demonstrated measurements on two-dimensional semiconductor ${\mathrm{WSe}}_{2}$, where energy-momentum dispersion valence conduction bands observed in single experiment. This provides direct momentum-resolved view, not only complete out-of-equilibrium gap but also its renormalization induced screening. Our establishes benchmark for measuring materials, excited-state spectral function.