UC Berkeley

The intriguing electronic properties of two-dimensional materials motivates experiments to resolve their rapid, microscopic interactions and dynamics across momentum space. Essential insight into the electronic momentum-space dynamics can be obtained directly via time- and angle-resolved photoemission spectroscopy (trARPES). We discuss the development of a high-repetition rate trARPES setup that employs a bright source of narrowband, extreme-UV harmonics around 22.3 eV, and its application to sensitive studies of materials dynamics. In the bulk transition-metal dichalcogenide MoSe2 momentum-space quasiparticle scattering is observed after resonant excitation at the K-point exciton line, resulting in the time-delayed buildup of electrons at the Σ-point conduction band minimum. We will discuss this and other aspects of the non-equilibrium electronic response accessible with the extreme-UV trARPES probe.