Tracing Electron Dynamics with Femtosecond Time-Resolved ARPES

Much of our current knowledge about electronic band structure in materials comes from angle-resolved photoemission spectroscopy (ARPES).  Extending traditional ARPES into the time domain opens the possibility of disentangling interactions between electron, phonon and spin degrees of freedom, all while directly tracking electron dynamics in energy-momentum space.  In this talk I will briefly describe some of the challenges of femtosecond time-resolved ARPES, and highlight some of the recent work in this field.  I will then present some of our initial results on graphene, the high-temperature superconductor Bi-2212 and the heavy fermion compound URu2Si2.  I will conclude by presenting some very preliminary results across the phase diagram of Bi-2212, using soft x-rays from LCLS tuned to the Copper L3 edge to photoexcite the system, while probing the ultrafast dynamics in the visible range.