Attosecond streaking of photoelectron emission from disordered solids

Abstract: Attosecond streaking of photoelectrons emitted by extreme ultraviolet light has begun to reveal how electrons behave during their transport within simple crystalline solids. Many sample types within nanoplasmonics, thin-film physics, and semiconductor physics, however, do not have a simple single crystal structure. The electron dynamics which underpin the optical response of plasmonic nanostructures and wide-bandgap semiconductors happen on an attosecond timescale. Measuring these dynamics using attosecond streaking will enable such systems to be specially tailored for applications in areas such as ultrafast opto-electronics. We show that streaking can be extended to this very general type of sample by presenting streaking measurements on an amorphous film of the wide-bandgap semiconductor tungsten trioxide, and on polycrystalline gold, a material that forms the basis of many nanoplasmonic devices. Our measurements reveal the near-field temporal structure at the sample surface, and photoelectron wavepacket temporal broadening consistent with a spread of electron transport times to the surface.