Environmental Liquid Cell Technique for Improved Electron Microscopic Imaging of Soft Matter in Solution

Abstract

Liquid-phase transmission electron microscopy is a technique for simultaneous imaging of the structure and dynamics of specimens in a liquid environment. The conventional sample geometry consists of a liquid layer tightly sandwiched between two Si3N4 windows with a nominal spacing on the order of 0.5 μm. We describe a variation of the conventional approach, wherein the Si3N4 windows are separated by a 10-μm-thick spacer, thus providing room for gas flow inside the liquid specimen enclosure. Adjusting the pressure and flow speed of humid air inside this environmental liquid cell (ELC) creates a stable liquid layer of controllable thickness on the bottom window, thus facilitating high-resolution observations of low mass-thickness contrast objects at low electron doses. We demonstrate controllable liquid thicknesses in the range 160 ± 34 to 340 ± 71 nm resulting in corresponding edge resolutions of 0.8 ± 0.06 to 1.7 ± 0.8 nm as measured for immersed gold nanoparticles. Liquid layer thickness 40 ± 8 nm allowed imaging of low-contrast polystyrene particles. Hydration effects in the ELC have been studied using poly-N-isopropylacrylamide nanogels with a silica core. Therefore, ELC can be a suitable tool for in situ investigations of liquid specimens.

Determining the radial distribution function of water using electron scattering: A key to solution phase chemistry

“…In order to realize a thin (135 nm), stable, and uniform water film for acquiring the electron scattering data, we used an in-house developed environmental liquid cell (ELC) assembly and method, the technical details of which will be published elsewhere. 66 The above-mentioned ELC setup incorporates silicon nitride (Si 3 N 4 ) flow-cell technology with a design based on that of Ref. 49, which was subsequently also utilized in Refs.…”

“…50,[54][55][56] This implies that microscopy and scattering signals are necessarily burdened with a significant background due to the Si 3 N 4 window material. Here, we present electron scattering data of liquid water at near-ambient temperature (23 ○ C) and pressure acquired using a recently developed environmental liquid cell (ELC) setup 66 that combines standard Si 3 N 4 flow cell approaches with windowed environmental cell technology, thus avoiding water layer bulging and enabling the maintenance of ideal layer thicknesses. 43,49,57 We provide a full analysis methodology of the obtained radial function pertaining to the combined water and Si 3 N 4 layers based on the existing x-ray data analysis approaches and include multiple scattering effects.…”

Challenges and Opportunities in Understanding Proton Exchange Membrane Fuel Cell Materials Degradation Using In‐Situ Electrochemical Liquid Cell Transmission Electron Microscopy

“…The fabrication procedure of the SiN x window chips for LCTEM holders can be found in the related literature. [70,101,102] In the following sections we discuss the windows' effects on imaging resolution, proper calibration of the Pt reference electrodes on LCTEM chips for electrochemical experiments, and the potential for chemical damage (radiolysis) that can be caused by the imaging electron beam.…”

“…Bearing in mind the pressure difference between the confined liquid-cell and the TEM column, it is expected that each thin window bows outward when the LCTEM holder is inserted into the column, which can be reduced using a pressure control over the fluidic flow lines. [102,103] The thickness of the space between the two windows, the liquid thickness, largely defines the achievable imaging performance. De Jong et al [93,104] has reviewed the fundamentals of TEM imaging resolution and signal-to-noise ratio of objects within liquid media in details.…”