This conference proceeding reports on the usage and applications of a high numerical aperture mirror for cathodoluminescence and other photon-based spectroscopies in a scanning transmission electron microscope.

Four-dimensional scanning transmission electron microscopy (4D-STEM) offers an attractive approach to simultaneously obtain precise structural determinations and capture details of local electric fields and charge densities. However, accurately extracting quantitative data at the atomic scale poses challenges, primarily due to probe propagation and size-related effects, which may even lead to misinterpretations of qualitative effects. In this study, we present a comprehensive analysis of electric fields and charge densities in both pristine and defective h-BN flakes. Through a combination of experiments and first-principle simulations, we demonstrate that while precise charge quantification at individual atomic sites is hindered by probe effects, 4D-STEM can directly measure charge transfer phenomena at the monolayer edge with sensitivity down to a few tenths of an electron and a spatial resolution on the order of a few angstroms.

Raw data set related to the article "μeV electron spectromicroscopy using free-space light", currently on arXiv (arXiv: 2212.12457)

Electron-photon temporal correlations in electron energy loss (EELS) and cathodoluminescence (CL) spectroscopies have recently been used to measure the relative quantum efficiency of materials. This combined spectroscopy, named Cathodoluminescence excitation spectroscopy (CLE), allows the identification of excitation and decay channels which are hidden in average measurements. Here, we demonstrate that CLE can also be used to measure excitation's decay time. In addition, the decay time as a function of the excitation energy is accessed, as the energy for each electron-photon pair is probed. We used two well-known insulating materials to characterize this technique, nanodiamonds with \textit{NV$^0$} defect emission and h-BN with a \textit{4.1 eV} defect emission. Both also exhibit marked transition radiations, whose extremely short decay times can be used to characterize the instrumental response function. It is found to be typically 2 ns, in agreement with the expected limit of the EELS detector temporal resolution. The measured lifetimes of \textit{NV$^0$} centers in diamond nanoparticles (20 to 40 ns) and \textit{4.1 eV} defect in h-BN flakes ($<$ 2 ns) matches those reported for those materials previously.

Direct electron detection is currently revolutionizing many fields of electron microscopy due to its lower noise, its reduced point-spread function, and its increased quantum efficiency. More specifically to this work, Timepix3 is a hybrid-pixel direct electron detector capable of outputting temporal information of individual hits in its pixel array. Its architecture results in a data-driven detector, also called event-based, in which individual hits trigger the data off the chip for readout as fast as possible. The presence of a pixel threshold value results in an almost readout-noise-free detector while also defining the hit time of arrival and the time the signal stays over the pixel threshold. In this work, we have performed various experiments to calibrate and correct the Timepix3 temporal information, specifically in the context of electron microscopy. These include the energy calibration, and the time-walk and pixel delay corrections, reaching an average temporal resolution throughout the entire pixel matrix of 1.37±0.04ns. Additionally, we have also studied cosmic rays tracks to characterize the charge dynamics along the volume of the sensor layer, allowing us to estimate the limits of the detector's temporal response depending on different bias voltages, sensor thickness, and the electron beam ionization volume. We have estimated the uncertainty due to the ionization volume ranging from about 0.8 ns for 60 keV electrons to 8.8 ns for 300 keV electrons.

The synergy between free electrons and light has recently been leveraged to reach an impressive degree of simultaneous spatial and spectral resolution, enabling applications in microscopy and quantum optics. However, the required combination of electron optics and light injection into the spectrally narrow modes of arbitrary specimens remains a challenge. Here, we demonstrate microelectronvolt spectral resolution in the nanoscale mapping of photonic modes with quality factors as high as 10$^4$. We rely on mode-matching of a tightly focused laser beam to whispering gallery modes to achieve a 10$^8$-fold increase in light-electron coupling efficiency. By adapting the shape and size of free-space optical beams to address specific physical questions, our approach allows us to interrogate any type of photonic structure with unprecedented spectral and spatial detail

In scanning transmission electron microscopy (STEM), following the advent of aberration correctors, a more recent breakthrough has been the development of new-generation monochromators, preserving the brightness of electron sources, and thus opening the way to new applications in Electron Energy-Loss Spectroscopy (EELS). More than just improving spectral resolution (now available in combination with atomic resolution), monochromation in EELS has given access to a whole new range of low-energy elementary excitations (down to the infrared range) with nanoscale resolution. The field of nano-optics using fast electron beams has been booming in recent years, boosted by recent developments in experiments combining photons and electrons in the microscope: cathodoluminescence (EELS), electron energy-gain spectroscopy (EEGS), photon-induced near-field electron microscopy, etc. Further advances are still to be expected by pushing the limits of time resolution, both as instrumentation advances and for accessing new physical information. I will review some of our latest results obtained in the field. This will encompass the observation by monochromated EELS/CL combined measurements of the nanoscale modification of WS 2 monolayers trion emission by local electromagnetic environment [1] the mapping of high-quality plasmons in copper nanostructures [2] or the three-dimensional vectorial imaging of surface phonon polaritons in MgO nanocubes [3]. Very recently, we have developed new acquisition schemes making use of a Timepix3 direct electron detector providing sub 10 ns time resolution over arbitrary EELS energy We introduce our technology for in situ studies inside transmission electron microscope (TEM), where next to heating and biasing studies, also environmental studies (i.e. in gaseous or liquid environments) are made possible. The systems rely on a Micro Electro-Mechanical System (MEMS)-based device as a smart sample carrier, which contains an integrated set of biasing electrodes or an integrated microheater, to enable in situ electrochemistry, battery research, catalytic studies and failure analysis, among others. As a result, the system provides users with the capability to visualize exciting dynamics in vacuum or liquid/gas environments as a function of different stimuli. In order to provide meaningful results and address historical challenges, our MEMS device controls the flow direction and ensures the gas/liquid will always pass through the region of interest. Thereby, the developed systems offer the opportunity to define the mass transport and control the kinetics of the reaction. Furthermore, the system´s modularity enables the user to remove the tip, referred to as a “lab-on-a-cartridge”, which can be inserted in the Synchrotron, in order to enable powerful correlative studies while keeping the environmental conditions constant. We believe that our developments will play a fundamental role in addressing many of the research questions within battery optimization, fuel cells, (electro)catalysis, as well as for advanced materials. The number of electrons in a beam can be parsed in many ways, but the total number is fixed. The faster you go, the fewer electron you have at each data point leaving you starved for counts. The same can be said for other data acquisition modes that parses the electrons into finer bins, such as increasing the energy dispersion to achieve better EELS resolution or reducing the energy selecting slit size to get sharper energy filtered images. The final limit of your experiment may not be the resolution of the hardware, but the Poisson or “shot” noise associated with counting discrete events. For a signal with N electrons, you can never have better noise than SQRT(N). microscopy in many ways, but they too cannot get around the SQRT(N) limit. However, due to the fast readout rate and sharp point spread function of these cameras, the traditional methods of acquiring electron microscopy data have been turned on their heads. In this presentation, we will discuss and illustrate the strategies for acquiring EELS, EFTEM and 4D STEM data using electron counting detector to optimally use the fixed number of electron available in the system. We will draw on examples from high-speed multimodal data acquisition and extreme low dose EELS fine structure analysis to demonstrate these strategies. Electron microscopy is an old technique -it has been in use for more than 90 years-, and whereas in Material Science it soon showed its great potential in structure determination, this has not been the case with biological molecules. The two main problems for this practical limitation are: a) the inability to find ways of preserving the three-dimensional structure of the molecules, which is maintained by weak bonds that are easily destroyed by electron radiation; b) the inability of properly determining the angular position of the particles during the tomographic, three-dimensional reconstruction procedure. Part of the first problem can be overcome witht the use of very low temperatures, and thus the name of cryoelectron microscopy. The rest of the limitation were successfully solved around 10 years ago, resulting in a revolution that is dominating structural biology and soon cell biology. The talk will deal with a description of the problems, show how they have been solved and what are the avenues that cryoelectron microscopy offers to biology. Liquid phase transmission electron microscopy LP EM offers remarkable capabilities with regard to imaging label-free, time-resolved structures in their native liquid media by removing the artefacts caused by traditional drying or cryogenic treatments. One of the most exciting applications of LP EM is the investigation of cell molecular machinery structures such as proteins. The liquid nature of the sample offers novel opportunities such as accessing previously inaccessible protein states or the possibility of 3D structure reconstruction by applying tomographic methods. The free movement of soft objects in LP EM allows for screening proteins’ structural landscape during the imaging process. Such a feature provides a unique selling point for the technique for structural biology investigations. We propose the combination of all-atom simulations with imaging via LP EM to complement protein structural studies with dynamic investigations. We have employed LP EM to investigate Amyloid- β (Aβ) aggregation. Aβ is a short 39-42 amino acid peptide that aggregates into larger assemblies, including neurotoxic oligomers, fibrils, and plaques. This process is highly associated with Alzheimer’s disease and has been of great interest to drug development research. The details of the aggregation pathway remain elusive, with much of the current knowledge arising from computational simulations and chemical kinetics investigations. We have been able to visualise processes including oligomers attaching to the surface of fibres, an essential step in secondary nucleation of A β and one of the most critical aggregation steps to consider for developing oligomer-targeting drugs. We have also been able to visualise the growth of a short fibril over a 10s video. This investigation demonstrates the capabilities of LP EM for imaging molecular aggregating systems over time in solution and in-situ. Although still in the early stages, the presented findings promise to provide relevant and novel biological information on Aβ aggregation pathways. Correlative light and electron microscopy (CLEM) entails a group of multimodal imaging techniques that are combined to pinpoint to the location of fluorescently labelled molecules in their ultrastructural context. Correlative super resolution and electron microscopy is one CLEM modality in which super resolution microscopy is used instead of conventional fluorescence microscopy techniques. Single-molecule localization microscopy (SMLM) is one of the super resolution microscopy families, offering excellent resolution (5–25 nm), multi-colour imaging and quantification capability with single-particle precision. Thus, the improved resolution of SMLM leads to a nanoscale localization precision of the specific fluorescent labels in the ultrastructural reference space provided by EM. Super-resCLEM methods have been mainly applied to biological samples; here we introduce it for materials. The decoration of nanoparticles functional is a key strategy to achieve targeting in The ligand to understand structure−activity However, to measure the address by a specifically by combining one of SMLM (DNA-PAINT) nanoparticle: functional ligands are counted by DNA-PAINT, while TEM provides the morphology and size.. Electron Energy Loss Spectroscopy (EELS) in the Transmission Electron Microscope (TEM) is a powerful tool to access materials atomic composition, oxidation state and optoelectronic properties at the nanoscale, and even with atomic resolution. With recent improvements in TEM instrumentation and EELS spectrometers, it is now possible and even frequent that in EELs experiments large Spectrum Images are obtained, containing a huge amount of data. So the problem arises of how to analyze this data in a fast and reliable way, independently of user biases, and allowing to access all the information contained therein. They have in common that they can all be rapidly (and easily) characterized by Scanning Electron Microscopy (SEM). SEM is a user-friendly complete technique to characterize a wide viaritey of samples for different applications, from cultural heritage objects and textiles, to cosmetics and innovative nanomedicines. The Dual Beam technique (FIB-SEM) is a smart solution to characterize a wide range of materials and to obtain nanoscale information about their structure and properties. It also allows the design and patterning of nanostructures opening new research lines in fields like nanoelectronics, sensors and quantum technologies. Fisher to operate in a of temperatures, fr

The acquisition of a hyperspectral image is nowadays a standard technique used in the scanning transmission electron microscope. It relates the spatial position of the electron probe to the spectral data associated with it. In the case of electron energy loss spectroscopy (EELS), frame-based hyperspectral acquisition is much slower than the achievable rastering time of the scan unit (SU), which sometimes leads to undesirable effects in the sample, such as electron irradiation damage, that goes unperceived during frame acquisition. In this work, we have developed an event-based hyperspectral EELS by using a Timepix3 application-specific integrated circuit detector with two supplementary time-to-digital (TDC) lines embedded. In such a system, electron events are characterized by their positional and temporal coordinates, but TDC events only by temporal ones. By sending reference signals from the SU to the TDC line, it is possible to reconstruct the entire spectral image with SU-limited scanning pixel dwell time and thus acquire, with no additional cost, a hyperspectral image at the same rate as that of a single channel detector, such as annular dark-field. To exemplify the possibilities behind event-based hyperspectral EELS, we have studied the decomposition of calcite (CaCO$_3$) into calcium oxide (CaO) and carbon dioxide (CO$_2$) under the electron beam irradiation.

Following optical excitations’ life span from creation to decay into photons is crucial in understanding materials photophysics. Macroscopically, this is studied using optical techniques, such as photoluminescence excitation spectroscopy. However, excitation and emission pathways can vary at nanometer scales, preventing direct access, as no characterization technique has the relevant spatial, spectral, and time resolution. Here, using combined electron spectroscopies, we explore excitations’ creation and decay in two representative optical materials: plasmonic nanoparticles and luminescent two-dimensional layers. The analysis of the energy lost by an exciting electron that is coincident in time with a visible-ultraviolet photon unveils the decay pathways from excitation toward light emission. This is demonstrated for phase-locked (coherent) interactions (localized surface plasmons) and non–phase-locked ones (point defect excited states). The developed cathodoluminescence excitation spectroscopy images energy transfer pathways at the nanometer scale, widening the available toolset to explore nanoscale materials.

Journal Article Unveiling Single Particle Coupling of Metallic Nanoparticles and Whispering Gallery Mode Resonators Get access Yves Auad, Yves Auad Laboratoire de Physique des Solides, Orsay, 91405, France Search for other works by this author on: Oxford Academic Google Scholar Cyrille Hamon, Cyrille Hamon Laboratoire de Physique des Solides, Orsay, 91405, France Search for other works by this author on: Oxford Academic Google Scholar Marcel Tencé, Marcel Tencé Laboratoire de Physique des Solides, Orsay, 91405, France Search for other works by this author on: Oxford Academic Google Scholar H Lourenço-Matins, H Lourenço-Matins Max Planck Institute for Biophysical Chemistry, G̈ottingen, 37077, GermanyIV. Physical Institute, University of G̈ottingen, G̈ottingen 37077, Germany Search for other works by this author on: Oxford Academic Google Scholar Vahagn Mkhitaryan, Vahagn Mkhitaryan ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, 08860 Castelldefels (Barcelona), Spain Search for other works by this author on: Oxford Academic Google Scholar Odile Stéphan, Odile Stéphan Laboratoire de Physique des Solides, Orsay, 91405, France Search for other works by this author on: Oxford Academic Google Scholar F Javier García de Abajo, F Javier García de Abajo ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, 08860 Castelldefels (Barcelona), SpainICREA-Institució Catalana de Recerca i Estudis Avançats, Passeig Lluís Companys 23, 08010 Barcelona, Spain Search for other works by this author on: Oxford Academic Google Scholar Luiz H G Tizei, Luiz H G Tizei Laboratoire de Physique des Solides, Orsay, 91405, France Search for other works by this author on: Oxford Academic Google Scholar Mathieu Kociak Mathieu Kociak Laboratoire de Physique des Solides, Orsay, 91405, France Search for other works by this author on: Oxford Academic Google Scholar Microscopy and Microanalysis, Volume 28, Issue S1, 1 August 2022, Pages 1962–1964, https://doi.org/10.1017/S1431927622007656 Published: 01 August 2022

An abstract is not available for this content so a preview has been provided. As you have access to this content, a full PDF is available via the ‘Save PDF’ action button.

An abstract is not available for this content so a preview has been provided. As you have access to this content, a full PDF is available via the ‘Save PDF’ action button.

An abstract is not available for this content so a preview has been provided. As you have access to this content, a full PDF is available via the ‘Save PDF’ action button.

Ultra-fast transmission electron microscopy (UTEM) combines sub-picosecond time-resolution with the versatility of TEM spectroscopies. It allows one to study the dynamics of materials properties combining complementary techniques. However, until now, time-resolved cathodoluminescence, which is expected to give access to the optical properties dynamics, was still unavailable in a UTEM. In this paper, we report time-resolved cathodoluminescence measurements in an ultrafast transmission electron microscope. We measured lifetime maps, with a 12 nm spatial resolution and sub-nanoseconds resolution, of nano-diamonds with a high density of NV center. This study paves the way to new applications of UTEM and to correlative studies of optically active nanostructures.

Whispering-gallery mode resonators host multiple trapped narrow-band circulating optical resonances that find applications in quantum electrodynamics, optomechanics, and sensing. However, the spherical symmetry and low field leakage of dielectric microspheres make it difficult to probe their high-quality optical modes using far-field radiation. Even so, local field enhancement from metallic nanoparticles (MNPs) coupled to the resonators can interface the optical far field and the bounded cavity modes. In this work, we study the interaction between whispering-gallery modes and MNP surface plasmons with nanometric spatial resolution by using electron-beam spectroscopy with a scanning transmission electron microscope. We show that gallery modes are induced over a selective spectral range of the nanoparticle plasmons, and additionally, their polarization can be controlled by the induced dipole moment of the MNP. Our study demonstrates a viable mechanism to effectively excite high-quality-factor whispering-gallery modes and holds potential for applications in optical sensing and light manipulation.

This file contains the raw dataset used in the manuscript "Tailored Nanoscale Plasmon-Enhanced Vibrational Electron Spectroscopy" published in L. H. G. Tizei et al Nano Letters, 2020 (doi: 10.1021/acs.nanolett.9b04659) Data has been acquired using Nion Swift (https://nionswift.readthedocs.io/en/stable/). Experimental details can be found in L. H. G. Tizei et al Nano Letters, 2020 (doi: 10.1021/acs.nanolett.9b04659). The dataset has been analyzed using the following Python libraries: Numpy, Scipy, Hyperspy, Matplotlib EELS hyperspectral images have been aligned using the Hyperspy "align1D" method. Aligned EELS hyperspectral images are saved in files finished with "_Aligned.hspy": For the strong coupling experiments: Tip 1 is on hBN Tip 2 is on vacuum For each of the nanowires tips, a file with the fitted coefficients are available, as well as a plot of the data and the fitted curve. Datasets have been fitted with gaussian and/or lorentizan functions, as described in the published text. Any question can be forwarded to the corresponding authors of the published text.

An abstract is not available for this content so a preview has been provided. As you have access to this content, a full PDF is available via the ‘Save PDF’ action button.

This paper discusses the reconstruction of partially sampled spectrum-images to accelerate the acquisition in scanning transmission electron microscopy (STEM). The problem of image reconstruction has been widely considered in the literature for many imaging modalities, but only a few attempts handled 3D data such as spectral images acquired by STEM electron energy loss spectroscopy (EELS). Besides, among the methods proposed in the microscopy literature, some are fast but inaccurate while others provide accurate reconstruction but at the price of a high computation burden. Thus none of the proposed reconstruction methods fulfills our expectations in terms of accuracy and computation complexity. In this paper, we propose a fast and accurate reconstruction method suited for atomic-scale EELS. This method is compared to popular solutions such as beta process factor analysis (BPFA) which is used for the first time on STEM-EELS images. Experiments based on real as synthetic data will be conducted.