Direct Optical Coupling to an Unoccupied Dirac Surface State in the Topological Insulator Bi${}_2$Se${}_3$

Jonathan A. Sobota, Shuolong Yang, Alexander F. Kemper +9

We characterize the occupied and unoccupied electronic structure of the topological insulator Bi${}_2$Se${}_3$ by one-photon and two-photon angle-resolved photoemission spectroscopy an…