2019 Volume 88 Issue 11 Pages 716-719
The functionalities of materials are governed by their electronic states and it is significantly important to trace their temporal variations to understand their dynamics. This paper describes the principles of time-resolved measurements by photoelectron spectroscopy that directly probes the electronic states of matter. The paper introduces research examples of carrier dynamics in graphene layers, grown on SiC substrates, at the time scale from femtoseconds to nanoseconds. Temporal evolution of the Dirac Fermions in graphene indicates a significant role of the scattering process at the Dirac point. Selective chemical measurements at the overlayer/substrate interface revealed the distinguishing carrier dynamics between graphene and SiC crystals. These research projects demonstrate that measurements by time-resolved soft X-ray photoemission spectroscopy are significant for developing the next generation of ultrafast devices.