Nanometer Resolution Elemental Mapping in Graphene-based TEM Liquid Cells

TL;DR

This paper introduces a novel graphene-based liquid cell design enabling nanometer-resolution elemental mapping in liquid TEM, facilitating detailed studies of nanoparticles with improved analytical capabilities.

Contribution

The work presents a new graphene liquid cell design with controlled volume and thickness, allowing high-resolution imaging and elemental mapping at the nanometer scale.

Findings

Achieved 1 nm spatial resolution elemental mapping of bimetallic nanoparticles.

Demonstrated reliable, reusable liquid cells with precise control over liquid volume.

Enabled tracking of nanoparticle dynamics in liquid with high resolution.

Abstract

We demonstrate a new design of graphene liquid cell consisting of a thin lithographically patterned hexagonal boron nitride crystal encapsulated from both sides with graphene windows. The ultra-thin window liquid cells produced have precisely controlled volumes and thicknesses, and are robust to repeated vacuum cycling. This technology enables exciting new opportunities for liquid cell studies, providing a reliable platform for high resolution transmission electron microscope imaging and spectral mapping. The presence of water was confirmed using electron energy loss spectroscopy (EELS) via the detection of the oxygen K-edge and measuring the thickness of full and empty cells. We demonstrate the imaging capabilities of these liquid cells by tracking the dynamic motion and interactions of small metal nanoparticles with diameters of 0.5-5 nm. We further present an order of magnitude improvement in the analytical capabilities compared to previous liquid cell data, with 1 nm spatial resolution elemental mapping achievable for liquid encapsulated bimetallic nanoparticles using energy dispersive X-ray spectroscopy (EDXS).