scholarly journals Multi-step atomic mechanism of platinum nanocrystals nucleation and growth revealed by in-situ liquid cell STEM

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Walid Dachraoui ◽  
Trond R. Henninen ◽  
Debora Keller ◽  
Rolf Erni
Keyword(s):  
Liquid Phase ◽  
Driving Forces ◽  
Classical Model ◽  
Theoretical Models ◽  
Atomic Scale ◽  
Single Atom ◽  
Growth Mechanisms ◽  
Platinum Nanocrystals ◽  
Scanning Transmission

AbstractThe understanding of crystal growth mechanisms has broadened substantially. One significant advancement is based in the conception that the interaction between particles plays an important role in the growth of nanomaterials. This is in contrast to the classical model, which neglects this process. Direct imaging of such processes at atomic-level in liquid-phase is essential for establishing new theoretical models that encompass the full complexity of realistic scenarios and eventually allow for tailoring nanoparticle growth. Here, we investigate at atomic-scale the exact growth mechanisms of platinum nanocrystals from single atom to final crystals by in-situ liquid phase scanning transmission electron microscopy. We show that, after nucleation, the nanocrystals grow via two main stages: atomic attachment in the first stage, where the particles initially grow by attachment of the atoms until depletion of the surrounding zone. Thereafter, follows the second stage of growth, which is based on particle attachment by different atomic pathways to finally form mature nanoparticles. The atomic mechanisms underlying these growth pathways are distinctly different and have different driving forces and kinetics as evidenced by our experimental observations.

Multimodal Optical Nanoprobe for Advanced In-Situ Electron Microscopy

2012 ◽  
Vol 20 (6) ◽  
pp. 32-37 ◽  
Author(s):  
Y. Zhu ◽  
M. Milas ◽  
M.-G. Han ◽  
J.D. Rameau ◽  
M. Sfeir
Keyword(s):  
Electron Microscopy ◽  
Driving Forces ◽  
Atomic Scale ◽  
Magnetic Domains ◽  
Photovoltaic Devices ◽  
Electromagnetic Devices ◽  
In Situ Electron Microscopy ◽  
Electric And Magnetic Fields ◽  
Anions And Cations

In-situ electron microscopy has gained considerable attention in recent years. It provides a “live” view of a material or device under study at various length scales. For example, by heating or cooling a sample one can study structural change at the atomic scale to understand the driving forces and mechanisms of phase transitions. By applying electric and magnetic fields on a ferroelectric or magnetic architecture in operation, one can directly observe how electric and magnetic domains switch, how anions and cations shift their positions, and how spins change their configuration across a domain wall, aiding the development of better electromagnetic devices. In the study of photovoltaic devices and junctions, a major challenge is to directly correlate light-induced electric currents with local structural inhomogeneities and dynamics. Such a capability would allow us to evaluate the performance of individual p-n junctions and to improve optoelectronic efficiency.

scholarly journals Single-atom vibrational spectroscopy in the scanning transmission electron microscope

Science ◽  
2020 ◽  
Vol 367 (6482) ◽  
pp. 1124-1127 ◽  
Author(s):  
F. S. Hage ◽  
G. Radtke ◽  
D. M. Kepaptsoglou ◽  
M. Lazzeri ◽  
Q. M. Ramasse
Keyword(s):  
Electron Microscope ◽  
Vibrational Spectroscopy ◽  
Materials Science ◽  
Scanning Transmission Electron Microscope ◽  
Atomic Scale ◽  
Single Atom ◽  
Phonon Modes ◽  
Resonant States ◽  
Resolution Electron ◽  
Scanning Transmission

Single-atom impurities and other atomic-scale defects can notably alter the local vibrational responses of solids and, ultimately, their macroscopic properties. Using high-resolution electron energy-loss spectroscopy in the electron microscope, we show that a single substitutional silicon impurity in graphene induces a characteristic, localized modification of the vibrational response. Extensive ab initio calculations reveal that the measured spectroscopic signature arises from defect-induced pseudo-localized phonon modes—that is, resonant states resulting from the hybridization of the defect modes and the bulk continuum—with energies that can be directly matched to the experiments. This finding realizes the promise of vibrational spectroscopy in the electron microscope with single-atom sensitivity and has broad implications across the fields of physics, chemistry, and materials science.

scholarly journals Visualizing single atom dynamics in heterogeneous catalysis using analytical in situ environmental scanning transmission electron microscopy

2020 ◽  
Vol 378 (2186) ◽  
pp. 20190605
Author(s):  
Edward D. Boyes ◽  
Alec P. LaGrow ◽  
Michael R. Ward ◽  
Thomas E. Martin ◽  
Pratibha L. Gai
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Scanning Transmission Electron Microscopy ◽  
Single Atom ◽  
Environmental Scanning ◽  
Technological Processes ◽  
Scanning Transmission Electron ◽  
Transmission Electron ◽  
Scanning Transmission

Progress is reported in analytical in situ environmental scanning transmission electron microscopy (ESTEM) for visualizing and analysing in real-time dynamic gas–solid catalyst reactions at the single-atom level under controlled reaction conditions of gas environment and temperature. The recent development of the ESTEM advances the capability of the established ETEM with the detection of fundamental single atoms, and the associated atomic structure of selected solid-state heterogeneous catalysts, in catalytic reactions in their working state. The new data provide improved understanding of dynamic atomic processes and reaction mechanisms, in activity and deactivation, at the fundamental level; and in the chemistry underpinning important technological processes. The benefits of atomic resolution-E(S)TEM to science and technology include new knowledge leading to improved technological processes, reductions in energy requirements and better management of environmental waste. This article is part of a discussion meeting issue ‘Dynamic in situ microscopy relating structure and function’.

Atomic-Scale Imaging and Spectroscopy for In Situ Liquid Scanning Transmission Electron Microscopy

2012 ◽  
Vol 18 (3) ◽  
pp. 621-627 ◽  
Author(s):  
Katherine L. Jungjohann ◽  
James E. Evans ◽  
Jeffery A. Aguiar ◽  
Ilke Arslan ◽  
Nigel D. Browning
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Scanning Transmission Electron Microscopy ◽  
Path Length ◽  
Atomic Scale ◽  
Scanning Transmission Electron ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Aberration Corrected

AbstractObservation of growth, synthesis, dynamics, and electrochemical reactions in the liquid state is an important yet largely unstudied aspect of nanotechnology. The only techniques that can potentially provide the insights necessary to advance our understanding of these mechanisms is simultaneous atomic-scale imaging and quantitative chemical analysis (through spectroscopy) under environmental conditions in the transmission electron microscope. In this study we describe the experimental and technical conditions necessary to obtain electron energy loss (EEL) spectra from a nanoparticle in colloidal suspension using aberration-corrected scanning transmission electron microscopy (STEM) combined with the environmental liquid stage. At a fluid path length below 400 nm, atomic resolution images can be obtained and simultaneous compositional analysis can be achieved. We show that EEL spectroscopy can be used to quantify the total fluid path length around the nanoparticle and demonstrate that characteristic core-loss signals from the suspended nanoparticles can be resolved and analyzed to provide information on the local interfacial chemistry with the surrounding environment. The combined approach using aberration-corrected STEM and EEL spectra with the in situ fluid stage demonstrates a plenary platform for detailed investigations of solution-based catalysis.

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