Ultrafast field-driven monochromatic photoemission from carbon nanotubes

TL;DR

This paper demonstrates ultrafast, monochromatic electron emission from carbon nanotubes excited by a femtosecond laser at 410 nm, achieving unprecedented energy spread compression and promising advances in ultrafast microscopy and light-wave electronics.

Contribution

The study introduces a novel carbon nanotube-based ultrafast electron source with highly monochromatic emission, surpassing conventional sources in energy spread and phase synchronization.

Findings

Energy spread compressed to 0.25 eV

Achieved field-driven photoemission at 410 nm

Enhanced prospects for attosecond imaging

Abstract

Ultrafast electron pulses, combined with laser-pump and electron-probe technologies, allow for various forms of ultrafast microscopy and spectroscopy to elucidate otherwise challenging to observe physical and chemical transitions. However, the pursuit of simultaneous ultimate spatial and temporal resolution has been largely subdued by the low monochromaticity of the electron pulses and their poor phase synchronization to the optical excitation pulses. State-of-the-art photon-driven sources have good monochromaticity but poor phase synchronization. In contrast, field-driven photoemission has much higher light phase synchronization, due to the intrinsic sub-cycle emission dynamics, but poor monochromaticity. Such sources suffer from larger electron energy spreads (3 - 100 eV) attributed to the relatively low field enhancement of the conventional metal tips which necessitates long pump wavelengths (> 800 nm) in order to gain sufficient ponderomotive potential to access the field-driven regime. In this work, field-driven photoemission from ~1 nm radius carbon nanotubes excited by a femtosecond laser at a short wavelength of 410 nm has been realized. The energy spread of field-driven electrons is effectively compressed to 0.25 eV outperforming all conventional ultrafast electron sources. Our new nanotube-based ultrafast electron source opens exciting prospects for attosecond imaging and emerging light-wave electronics.