Structural & Electronic Surface Dynamics
Structural & Electronic Surface Dynamics
Research Group Ralph Ernstorfer, MP Fellow
Research Group Ralph Ernstorfer, MP Fellow

News Post
New paper: Excited-state band mapping.
Feb 2022

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 to those dynamic states above the Fermi level that determine technologically relevant transport properties. We extend band structure mapping into the unoccupied states and across the entire Brillouin zone by using a state-of-the-art high repetition rate, extreme ultraviolet femtosecond light source to probe optically excited samples. The wide-ranging applicability and power of this approach are demonstrated by measurements on the two-dimensional semiconductorWSe2, where the energy-momentum dispersion of valence and conduction bands are observed in a single experiment. This provides a direct momentum-resolved view, not only on the complete out-of-equilibrium band gap but also on its renormalization induced by electronic screening. Our work establishes a benchmark for measuring the band structure of materials, with direct access to the energy-momentum dispersion of the excited-state spectral function.

Puppin et al., Phys. Rev. B 105, 075417 (2022).