Signatures and mechanisms of plasmon-enhanced electron emission from clusters in few-cycle laser fields

Intense laser pulses with well-defined waveforms enable unprecedented control over electronic strong-field processes in atoms, molecules and nanostructures. In particular, carrier-envelope phase (CEP) controlled few-cycle pulses allow the modification of various features in high-harmonic or photoelectron spectra. Vice versa, such signatures open up the opportunity to identify the underlying physical processes. Here, we utilize this approach to investigate plasmon-enhanced electron emission from simple metal clusters under resonant few-cycle laser pulses. Photoelectron energy spectra extracted from our semiclassical trajectory simulations reveal a set of pronounced but strongly intertwined CEP-dependent signatures. We find, that electron trajectories associated with these signatures can be categorized by two characteristic timestamps, i.e. the escape from the cluster and the last transit through its central plane. A correlation analysis of these times enables us to disentangle the intertwined features and to associate them with different acceleration mechanisms. We expect that our results will support the interpretation of specific patterns in the photoelectron spectra of future CEP-resolved cluster experiments.