Angular distribution of electron emission from ultrafast nanotip sources

TL;DR

This paper models and analyzes the angular distribution of electron emission from ultrafast tungsten nanotips, linking emission mechanisms to angular patterns and enabling optimization of electron source performance.

Contribution

It introduces a theoretical model that connects emission mechanisms with angular distribution and maps work function variations across the nanotip surface.

Findings

Identifies the relationship between emission mechanisms and angular distribution.

Provides a method to map work function variations on the nanotip surface.

Predicts electron emission characteristics based on laser power and tip voltage.

Abstract

We investigate the angular distribution of ultrafast laser-induced electron emission from a tungsten nanotip in the multiphoton regime. A theoretical model allows precise determination of the relative contribution of different electron emission mechanisms, revealing connections between emission mechanism and the angular distribution of emitted electrons. We infer a continuous map of the work function across the surface of the tip, which in combination with the model can be used to predict values including the number of electrons per pulse and the angular divergence of the resulting beam as a function of laser power and tip voltage for (310)-oriented tungsten nanotips. The model is straightforward to implement and can be used to optimize the performance of instruments using ultrafast nanotip electron sources.