Electron transparent graphene windows for environmental scanning electron microscopy in liquids and dense gases

TL;DR

This paper demonstrates the use of graphene membranes as transparent windows for environmental electron microscopy in liquids and gases, enabling high-resolution imaging of biological and nanomaterials.

Contribution

It introduces a reusable environmental cell with exchangeable graphene windows and evaluates imaging conditions for liquids using colloidal gold nanoparticles.

Findings

Graphene membranes allow electron transmission in liquids and gases.

Imaging of nanoparticles in liquids was successfully demonstrated.

Limitations include water radiolysis and membrane damage at high doses.

Abstract

Due to its ultrahigh electron transmissivity in a wide electron energy range, molecular impermeability, high electrical conductivity and excellent mechanical stiffness the suspended graphene membranes appear to be a nearly ideal window material for in situ (in vivo) environmental electron microscopy of nano- and mesoscopic objects (including bio-medical samples) immersed in liquids and/or in dense gaseous media. In this communication, taking advantage of little modification of the graphene transfer protocol on to metallic and SiN supporting orifices, the reusable environmental cells with exchangeable graphene windows have been designed. Using colloidal gold nanoparticles (50 nm) dispersed in water as model objects for scanning electron microscopy in liquids, the different imaging conditions through graphene membrane have been tested. The limiting factors for electron microscopy in liquids such as electron beam induced water radiolysis and damage of graphene membrane at high electron doses were discussed.