Wavelength-Dependent Features of Photoelectron Spectra from Nanotip Photoemission

Xiao-Yuan Wu,Liang-You Peng,Hao Liang,Marcelo Ciappina

doi:10.3390/photonics7040129

Abstract

If a metal nanotip is irradiated with the light of a wavelength much larger than the nanotip’s radius of curvature, optical near-fields become excited. These fields are responsible for distinct strong-field electron dynamics, due to both the field enhancement and spatial localization. By classical trajectory, Monte Carlo (CTMC) simulation, and the integration of the time-dependent Schrödinger equation (TDSE), we find that the photoelectron spectra for nanotip strong-field photoemission, irradiated by mid-infrared laser pulses, present distinctive wavelength-dependent features, especially in the mid- to high-electron energy regions, which are different from the well known ones. By extracting the electron trajectories from the CTMC simulation, we investigate these particular wavelength-dependent features. Our theoretical results contribute to understanding the photoemission and electron dynamics at nanostructures, and pave new pathways for designing high-energy nanometer-sized ultrafast electron sources.

Highlights

IntroductionStrong-field physics refers to an extreme light-matter interaction [1,2], which takes place when the force exerted by a light electric field is comparable to the binding force acting on electrons
Strong-field physics refers to an extreme light-matter interaction [1,2], which takes place when the force exerted by a light electric field is comparable to the binding force acting on electrons.Usually, in order to access the strong-field regime, high-intensity lasers are required
Comparing a series of simulation results at different wavelengths, we find distinctive wavelength-dependent features in the photoelectron spectra, in the mid to high electron energy region

Summary

Introduction

Strong-field physics refers to an extreme light-matter interaction [1,2], which takes place when the force exerted by a light electric field is comparable to the binding force acting on electrons. In order to access the strong-field regime, high-intensity lasers are required. The original scope of strong-field physics is focused on gas-phase atomic and molecular systems, where the most notable phenomena, such as high-order harmonic generation (HHG) [2,3,4], above-threshold ionization (ATI) [5,6,7] and non-sequential double ionization (NDSI) [8,9], have been extensively investigated, both theoretically and experimentally. Sharp nanometer-size metallic tips configure the fundamental blocks for investigating various strong-field phenomena at a much lower laser intensity [19,20,21]. Under the lightning rod effect, the moderate applied voltage translates into an enhanced electric field right at the tip’s apex

Methods

Results

Conclusion