Direct Observations of the Rotation and Translation of Anisotropic Nanoparticles Adsorbed at a Liquid–Solid Interface

Abstract

We can learn about the interactions between nanoparticles (NPs) in solution and solid surfaces by tracking how they move. Here, we use liquid cell transmission electron microscopy (TEM) to follow directly the translation and rotation of Au nanobipyramids (NBPs) and nanorods (NRs) adsorbed onto a SiN x surface at a rate of 300 frames per second. This study is motivated by the enduring need for a detailed description of NP motion on this common surface in liquid cell TEM. We will show that NPs move intermittently on the time scales of milliseconds. First, they rotate in two ways: (1) rotation around the center of mass and (2) pivoted rotation at the tips. These rotations also lead to different modes of translation. A NP can move through small displacements in the direction roughly parallel to its body axis (shuffling) or with larger steps via multiple tip-pivoted rotations. Analysis of the trajectories indicates that both displacements and rotation angles follow heavy-tailed power law distributions, implying anomalous diffusion. The spatial and temporal resolution afforded by our approach also revealed differences between the different NPs. The 50 nm NRs and 100 nm NBPs moved with a combination of shuffles and rotationmediated displacements after illumination by the electron beam. With increasing electron fluence, 50 nm NRs also started to move via desorption-mediated jumps. The 70 nm NRs did not exhibit translational motion and only made small rotations. These results describe how NP dynamics evolve under the electron beam and how intermittent pinning and release at specific adsorption sites on the solid surface control NP motion at the liquid−solid interface. We also discuss the effect of SiN x surface treatment on NP motion, demonstrating how our approach can provide broader insights into interfacial transport.

Interactions of sub-five-nanometer diameter colloidal palladium nanoparticles in solution investigated via liquid cell transmission electron microscopy

“…2À and Cl À should also be taken into account. 52 Note that, other electron beam induced effects such as the radiolysis reactions in the presence of Br À (from CTAB) and the charge re-distribution 58,59 on the CTA + -NPs were not considered. As predicted by Schneider et al, 52 the concentration of H + in solution under e-beam irradiation was almost unchanged when initial pH < 3, and thus we treated the initial solution pH ¼ 2.2 as a steady state.…”

Liquid phase transmission electron microscopy for imaging of nanoscale processes in solution

“…To minimize electron-beam effects, low electron flux and dose imaging can be the most effective route, which requires sensitive detectors. Recent advances in new CMOSbased direct electron detectors now enable us to record at milliseconds times resolution or higher, 50,51 and at lower electron fluxes, owing to their higher sensitivity, 52 which significantly reduces the effect of the beam on the observed process. Electron-beam effects can be complex, and there have been efforts in uncovering the mechanisms of electron-beam damage.…”

“…For example, minimizing the effects of the electron beam on the imaged processes is one of the important ones. 50,79,141 While beam effects can be drastically reduced by taking advantage of new direct electron detectors, there is an inherent tradeoff between electron flux, spatial and temporal resolutions because the images get increasingly noisy and less interpretable with decreasing electron flux on the camera. 50 Alleviating these challenges will require the development of adaptive image processing tools that can be trained using noisy image data sets of known structures to identify unknown structures and recognize the subtle LiqUid PhaSE TRanSMiSSiOn ELEcTROn MicROScOPy fOR iMaging Of nanOScaLE PROcESSES in SOLUTiOn structural transformations in low signal-to-noise ratio image sequences acquired for any given solution-based process.…”

Dynamic Imaging of Nanostructures in an Electrolyte with a Scanning Electron Microscope

“…This need has spurred the development of different reaction cells that integrate a fluid environment within various standard imaging platforms, such as fluorescence microscopy (Dukes et al, 2010;Peddie et al, 2014) and scanning probe microscopy (Hörber & Miles, 2003). Among the different techniques currently available for studying processes in liquid, liquid cell electron microscopy (LC-EM) occupies a unique niche since it allows for the direct (in situ) imaging of nanoparticles (NPs) and their dynamics without the need for labeling at relatively high frame rates up to a few hundred frames per second with state-of-the-art electron detectors (Liao et al, 2014;Park et al, 2015;Chee et al, 2016Chee et al, , 2019Lin et al, 2016).…”