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This white paper describes applications of cryoRaman, a cryogenic Raman microscope offering VIS to NIR excitation, high magnetic fields, and full polarization control.

Cutting-Edge Cryogenic Raman Microscope v2

This overview of advanced microparticle analysis shows how particles can be found, classified, and then identified automatically using confocal Raman microscopy.

ParticleScout for Automated Raman Imaging Analysis of Microparticles

This application note shows correlative Raman–SEM–EDS imaging investigations of Li-ion batteries that reveal charge cycle-induced chemical and structural changes.

Looking into Batteries with RISE Microscopy

This application note describes a correlative Raman–scanning electron microscope (SEM) investigation of a lithium-ion battery cathode before and after hundreds of charge cycles. The technique provides an exceptionally detailed chemical and structural analysis of degradation processes on the nanoscale.

Lithium-ion battery technology is the key enabler of the current revolution in transportation and energy. Improving the performance of Li-ion cells is among the highest priorities in contemporary research and a detailed understanding of how charging cycles affect their electrodes is crucial. In the following, we use correlative Raman imaging and scanning electron (RISE) microscopy to visualize changes in molecular composition and the formation of grain fractures.

The investigated lithium nickel manganese cobalt oxide (Li-NMC) cell was subjected to 400 charge cycles, leading to a 40% loss of capacity. Changes in performance are often a result of inhomogeneous degradation in battery electrodes. Local deterioration of microstructure in a Li-NMC battery electrode subjected to fast charging and long-term cycling was studied using a WITec/Tescan RISE microscopy system. This instrument allows samples to be automatically transferred from one measuring position to the other within a common vacuum chamber, enabling the correlation of Raman and SEM data, streamlining the experimental workflow and drastically improving ease of use. Cross sections were created for imaging with the integrated focused ion beam.

RISE analysis of the cathode of a fast-cycled Li-NMC battery (Sample courtesy of Dean Miller [Tescan USA])

Cross section of an uncycled cathode (a). Particles embedded in amorphous carbon (red) contain uniformly distributed lithium nickel cobalt manganese oxide (blue). Cross section of a cycled and rapidly charged cathode (b). Compared to the uncycled cathode, the particles appear inhomogeneous. Changes in peak positions and peak width indicate variance of Li-NMC composition. One particle (bottom left) shows a completely different composition, including a spectrum (blue) identical to the Li-NMC spectrum of the uncycled electrode. RISE image of a particle of a cycled cathode that reveals changes in Li-NMC composition and substantial structural degradation (c).

In the RISE image of the uncycled cathode (a) its particles appear to consist of uniform lithium nickel cobalt manganese oxide. Rapid cycling induced significant changes in lithiation of the particles as indicated by changes in the Raman spectra (green) (b). The Raman data reveals local variations even at the single-particle level. In b, one particle is characterized by two spectra, one of which corresponds to the Li-NMC spectrum of the native electrode, indicating that this particle might not have participated in the cycling process. Lorentzian fitting of the spectral peak positions of another particle also shows a high level of inhomogeneity and degradation in the form of cracks (c).

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This application note describes a correlative Raman–scanning electron microscope (SEM) investigation of a lithium-ion battery cathode before and after hundreds of charge cycles. The technique provides an exceptionally detailed chemical and structural analysis of degradation processes on the nanoscale.


Correlative Raman Imaging for Battery Research

This survey shows how Raman imaging can characterize food samples such as honey, chocolate, and fat spreads to help understand the products and production processes.  



Food Analysis with Confocal Raman Microscopy v3

Cutting-Edge Cryogenic Raman Microscope

In a demonstration of the new cryoRaman low-temperature Raman microscope’s capabilities, a tungsten diselenide flake on Si/SiO

 was investigated and its numbers of layers were determined.

Interest in Raman microscopy at cryogenic temperatures has been increasing across a range of scientific fields over the past two decades. Though initially the primary driver of applications was the carbon nanotubes and graphene community, a recent surge in the number of published cryogenic Raman studies is dominated by research on transition metal dichalcogenides and van der Waals heterostructures.

To meet both existing and evolving market requirements, cryoRaman was jointly developed by cryogenic specialists attocube systems and Raman microscope developer WITec GmbH. It offers excitation wavelengths from vis to NIR with optimized spectrometers, 1.6 to 300 K operating temperatures, high magnetic fields, unique cryogenically compatible Raman-specific objectives, and an exceptionally precise piezoelectric scan stage.

In the following demonstration, cryoRaman was used to investigate a WSe

, characterize its numbers of layers, and to establish the system’s sub-400 nm lateral resolution (1).

To measure the tungsten diselenide flake, a 532 nm laser was used for excitation, and a RayShield coupler allowed detection of Raman bands down to ~±10 1/cm. The experimental setup also included a UHTS300 spectrometer optimized for detection in the visible range with an 1800 g/mm grating and a back-illuminated CCD camera.

The cryostat cooled the sample to 120 K. An LT-APO 532-Raman objective with a numerical aperture of 0.82 and piezoelectric positioners controlled through the Control Five software were used. The acquired data set was evaluated with the Project Plus software package.

Images of the tungsten diselenide that show different numbers of layers were acquired and combined in the false color image shown in Figure 1a. It is color-coded according to the Raman spectra shown in Figure 1b. The image is 30 × 30 μm

 in size with 400 × 400 pixels and was created with an integration time of 150 ms per spectrum. A zoomed-in image (Figure 1c) shows the low-wavenumber area with the most prominent peaks for the double and triple layers as labelled.

 of various layer numbers at 120K. (a) Combined false-color image showing the location of the different numbers of layers. (b) Raman spectra of the layers in the corresponding colors and (c) zoom-in of the spectra around the Rayleigh peak.

The cryoRaman microscopy system offers researchers a fast, user-friendly and versatile tool for examining transition metal dichalcogenide samples and determining their numbers of layers at very low temperatures. Its sub-400 nm lateral resolution together with low-wavenumber detection, high magnetic fields, and polarization control all make it unique in the marketplace. These capabilities will be of great use as research on 2D materials and TMDs continues.

(1) Extracted from the white paper: Cutting-edge Cryogenic Raman Microscope. https://www.witec.de/assets/Literature/Files/AppNote-cryoRaman.pdf

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Cryogenic Raman Imaging of a Tungsten Diselenide Flake

This study describes the generation of 3D images of pharmaceutical, biological, and geological samples using image stacking enabled by a highly confocal beam path.


3D Raman Imaging—Best Practice Examples from Various Fields of Application