3D characterization of heat-induced morphological changes of Au nanostars by fast in-situ electron tomography

Abstract

A thorough understanding of the thermal stability and potential reshaping of anisotropic gold nanostars is required for various potential applications. Combination of a tomographic heating holder with fast tilt series acquisition has been used to monitor temperature-induced morphological changes of Au nanostars. The outcome of our 3D investigations can be used as an input for boundary element method simulations, enabling us to investigate the influence of reshaping on the nanostars' plasmonic properties. Our work leads to a better understanding of the mechanism behind thermal reshaping. In addition, the approach presented here is generic and can hence be applied to a wide variety of nanoparticles made of different materials and with arbitrary morphology.

Quantitative 3D Characterization of Elemental Diffusion Dynamics in Individual Ag@Au Nanoparticles with Different Shapes

“…Since a conventional electron tomography experiment is quite time-consuming, we employed a fast HAADF-STEM tomography methodology, which comprises fast tilting of the specimen holder and continuous tracking of the sample. 33 In this manner, such a challenging experiment, where in total 33 tomographic series needed to be acquired, became feasible. From the obtained HAADF-STEM reconstructions we retrieved 3D compositional information on the different states of alloying for each studied nanoparticle, which we describe in the following.…”

“…The improved signal-to-noise ratio is not surprising, since the cross-section for the HAADF-STEM signal is generally 6 orders of magnitude higher than that of EDX. 42 The high signal-to-noise ratio of our method, combined with the fast HAADF-STEM tomography approach, 33 enabled us to retrieve a full 3D compositional distribution in a given nanoparticle in only ∼10 min. In this manner, it became possible to follow the complete timeline of the alloying process in situ during a single experiment for several particles.…”

“…48 Tilt series for the nanoparticles were acquired between −75°and 75°using a fast tomography approach, described elsewhere. 33 The projection images were acquired with 50 pA beam current and 1 s exposure time. Image resolution constituted 1024 × 1024 pixels with a pixel size of 0.212 nm.…”

Deep learning-based noise filtering toward millisecond order imaging by using scanning transmission electron microscopy

“…Keywords: scanning transmission electron microscopy, image processing, deep learning, noise filtering, dislocation Transmission electron microscopy (TEM) is commonly used in various fields such as materials science 1,2 , biology 3 , and so on. Recent advancement of TEM technique has enabled us to conduct various kinds of in situ observation with different external stimuli, e.g., loading 4,5 , heating 6,7 , etc.…”

Fast electron low dose tomography for beam sensitive materials

“…In a conventional electron tomography experiment, pre-acquisition steps, such as focusing and tracking at every tilt angle needs additional acquisition time and electron dose. Recently, we proposed an acquisition approach where a tilt series of 2D high angle annular dark field scanning transmission electron microscopy (HAADF-STEM) projection images is acquired by continuously tilting the holder and simultaneously acquiring projection images while focusing and tracking the particle [1,2]. For HAADF-STEM, this approach results in an electron dose reduction of almost an order of magnitude and an acquisition time of a few minutes instead of an hour or longer.…”