Controlling radiolysis chemistry on the nanoscale in liquid cell scanning transmission electron microscopy

Abstract

When high-energy electrons from a scanning transmission electron microscope (STEM) are incident on a liquid, the vast majority of the chemical reactions that are observed are induced by the radiolysis...

Understanding the Dynamics of Molecular Water Oxidation Catalysts with Liquid-Phase Transmission Electron Microscopy: The Case of Vitamin B12

“…As one of the critical challenges in liquid phase TEM is to avoid any electron beam damage and radiolysis effects, 64 we performed all experiments in the low dose TEM in order to minimize the electron beam-induced artifacts during our EC-LTEM studies. Moreover, all our in situ TEM studies were carried out under the same, carefully adjusted illumination conditions (emission, spot size, condenser aperture, condenser lens value, magnification, and proper electrolyte flow rate) to stay below the threshold for any detectable nanostructure changes in a field of view.…”

AXON Dose: A Solution for Measuring and Managing Electron Dose in the TEM

“…One common approach is to use "low dose" techniques that seek to minimize the beam/sample interactions to a level where they do not substantially impact the sample or the analysis results [1]. These efforts to limit both the cumulative electron dose (e -/Å 2 ) and the dose rate (e -/Å 2 s) are well documented in the literature both for conventional and in situ TEM, especially for techniques sensitive to radiolysis, such as liquid EM [2][3][4]. A more advanced approach would allow users to calibrate their TEM, quantify dose and dose rate throughout an experiment, and control either parameter within a user-defined threshold.…”

Spatial Distribution of the Electron Dose and the Effects on Beam Damage in STEM

“…This model was then extended to include a chemical model of the radiolysis of water [5] to study how subsampling effects the formation of hydrogen bubbles during in-situ liquid STEM experiments. Linehop subsampling was shown to reduce the amount of hydrogen produced not due to a reduced number of electrons, but due to a more efficient distribution of electrons resulting in a reduction in the amount of beam overlap that occurs [6]. Figure 2 (A) The average H2 concentration produced from a series of scans obtained with a step separation of 1 pixel (B), 2 pixels (C), 4 pixels (D), 8 pixels (E) and 16 pixels (F).…”

“…For all scans the total beam dose and dose rate was kept constant with the only difference being the spatio-temporal profile of the beam delivery, i.e. the separation in space and time of the electrons hitting the liquid cell [6].…”