Defining the radiation chemistry during liquid cell electron microscopy to enable visualization of nanomaterial growth and degradation dynamics

Abstract

We present a critical review of methods for defining the chemical environment during liquid cell electron microscopy investigation of electron beam induced nanomaterial growth and degradation. We draw from the radiation chemistry and liquid cell electron microscopy literature to present solution chemistry and electron beam-based methods for selecting the radiolysis products formed and their relative amount during electron irradiation of liquid media in a transmission electron microscope. We outline various methods for establishing net oxidizing or net reducing reaction environments and propose solvents with minimal overall production of radicals under the electron beam. Exemplary liquid cell electron microscopy experiments in the fields of nanoparticle nucleation, growth, and degradation along with recommendations for best practices and experimental parameters are reported. We expect this review will provide researchers with a useful toolkit for designing general chemistry and materials science liquid cell electron microscopy experiments by 'directing' the effect of the electron beam to understand fundamental mechanisms of dynamic nanoscale processes as well as minimizing radiation damage to samples.

Liquid‐Phase Transmission Electron Microscopy for Studying Colloidal Inorganic Nanoparticles

“…It is also a consensus that extensive understanding is still needed to quantitatively control the beam effect. More details about current understanding on the electron‐beam effects can be found in another recent review paper …”

Nanoscale Imaging and Stabilization of Silica Nanospheres in Liquid Phase Transmission Electron Microscopy

“…The majority of the published articles highlight an important challenge in liquid phase TEM, which is to distinguish electron beam induced effects from the phenomena under investigation, and ultimately to suppress these effects. Along with the beam damage already known from TEM imaging in vacuum, liquid phase TEM suffers from additional beam induced effects, the most prominent challenge being the formation of radicals and other reactive species in the liquid upon electron beam irradiation, which significantly changes local chemistry . It was recently found that such a change in chemistry also affects oxides, materials usually considered quite stable under electron beam irradiation .…”

Utilizing Electron Beam Control and Radiation Chemistry during Liquid Cell Electron Microscopy to Image Protein Aggregates in their Native Hydrated State

“…While this approach allows for direct imaging of nanoscale samples in a thin ( ) liquid layer [4], radiation damage quickly deteriorates the tertiary and quaternary structure of protein aggregates [5,6]. Radiation damage is due mainly to oxidizing radicals created from electron beam induced radiolysis in the liquid layer [7,8]. In this talk, I will outline our recently developed experimental approaches to mitigate radiation damage and enable damage-free imaging of protein aggregate structure and other beam sensitive soft materials.…”

“…In this talk, I will outline our recently developed experimental approaches to mitigate radiation damage and enable damage-free imaging of protein aggregate structure and other beam sensitive soft materials. These approaches include (1) the addition of radical scavengers [8] to selectively eliminate oxidizing radicals and (2) the use of advanced electron beam control during imaging to reduce the overall production of damaging radicals.…”