Ultrafast XUV photoelectron spectroscopy: source development and applications

The ultrafast pulses of extreme ultraviolet radiation produced through high harmonic generation (HHG) have great potential for applications in photoelectron spectroscopy in gases, liquids and solids. They can be used in time- and angle-resolved photoemission spectroscopy (tr-ARPES), a powerful technique for directly observing electron dynamics in condensed matter. In this talk I show examples of the application of tr-ARPES with HHG to graphene. Exploiting graphene’s novel properties for applications in optoelectronics requires understanding of the electron dynamics at the Dirac points in graphene, where a photon energy of >16 eV is needed. We are now able to carry out tr-ARPES measurements with sub-10 femtosecond temporal resolution, while still retaining the sub-eV energy resolution which allows spectroscopic techniques to be used to interpret the data.
A key future direction for our work is to use HHG at higher photon energies. We are developing a few-cycle source in the infrared at 1700 nm with the aim of generating HHG photons into the water window. I will also present first results from this work including pulse characterisation and OPA modelling.