Electron rescattering at metal nanotips induced by ultrashort laser pulses

TL;DR

This paper investigates electron rescattering phenomena at metal nanotips induced by ultrashort laser pulses, revealing strong-field effects at low intensities and using the cut-off as a probe for local electric fields.

Contribution

It is the first to observe plateau and cut-off structures in photoelectron spectra from nano-scale metal tips under few-cycle laser pulses, highlighting surface effects and field enhancement.

Findings

Plateau and cut-off structures observed at low laser intensities.

Enhanced electron yield compared to atomic systems.

Cut-off position as a probe for local electric fields.

Abstract

We report on the first investigation of plateau and cut-off structures in photoelectron spectra from nano-scale metal tips interacting with few-cycle near-infrared laser pulses. These hallmarks of electron rescattering, well-known from atom-laser interaction in the strong-field regime, appear at remarkably low laser intensities with nominal Keldysh parameters of the order of $\gtrsim 10$. Quantum and quasi-classical simulations reveal that a large field enhancement near the tip and the increased backscattering probability at a solid-state target play a key role. Plateau electrons are by an order of magnitude more abundant than in comparable atomic spectra, reflecting the high density of target atoms at the surface. The position of the cut-off serves as an in-situ probe for the locally enhanced electric field at the tip apex.