News

August 2020

WITec Announces Virtual Raman Imaging Poster Summit 2020

Online conference offers the Raman community a forum for scientific exchange

Ulm, Germany
August 11th, 2020

WITec GmbH, technology leader in Raman microscopy, is hosting its first Virtual Raman Imaging Poster Summit from September 28th to October 2nd, 2020.  

This online conference offers the worldwide Raman community the chance to present and discuss their work from the convenience of their homes or home laboratories. Session topics will include: Life Sciences, Biomedical and Pharma Research, Advanced Materials Analysis, Environmental and Geosciences, and Correlative Imaging Applications.

The Virtual Raman Imaging Poster Summit takes the place of the Confocal Raman Imaging Symposium in the calendar of premiere events for chemical imaging and spectroscopy. The annual Symposium is acclaimed for both the diversity of the disciplines represented in its presentations, and its sociable atmosphere. The Virtual Raman Imaging Poster Summit will preserve both of these qualities while moving to a distributed format in response to the ongoing pandemic.

As expressed by Harald Fischer, Marketing Director at WITec, “We can’t wait to see what the Raman community has been up to. Even in these uncertain times, scientific progress continues and people are understandably excited about their latest discoveries. The Virtual Raman Imaging Poster Summit is in 2020 the best platform for sharing that excitement.”

Participants will be able to discuss the research presented through an online chat tool and send questions directly to the poster authors. To conclude the event, everyone will have the chance to vote for their favorite in the Best Poster Award competition. The deadline to submit an abstract for the conference is September 15th, 2020.

For further details, please see the Virtual Poster Summit 2020 homepage:
www.raman-symposium.com/virtual-poster-summit

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July 2020

Correlative high-resolution imaging of TMDs – Raman, SHG and PL imaging of an MoS2 flake

Two-dimensional (2D) materials such as transition metal dichalcogenides (TMDs) are receiving increasing attention due to their unique optical and electronic properties. Their possible applications include the production of transistors, photo detectors, light emitting diodes (LEDs) and photovoltaic cells. In order to produce high-quality devices, synthesis processes must be evaluated efficiently. Thus, non-destructive imaging techniques are required for monitoring crystal properties and features such as grain boundaries, layer number, defect density, doping and strain fields.

In our new application note, we present a series of measurements of CVD-grown mono-layer molybdenum disulfide (MoS2), which illustrate the advantages of correlative Raman, second harmonic generation (SHG) and photoluminescence (PL) microscopy for investigating TMDs. All measurements were performed at the same area of interest using a WITec alpha300 microscope equipped with a 532 nm laser for Raman and PL imaging and a picosecond-pulsed 1064 nm laser for SHG excitation.

Strain fields in the crystal were visualized by Raman and PL imaging, as both the frequency of the E2g Raman mode (upper left image) and the wavelength of the PL signal (lower left image) were red-shifted in the same areas. Rim effects around the border of the MoS2 flake were clearly visible in the PL image (lower left image), as well as in the image of the A1g Raman mode (see the attached application note).

SHG microscopy is sensitive to changes in crystal orientation and symmetry and visualized grain boundaries in the MoS2 flake (upper right picture). Additionally, polarization-dependent SHG measurements can identify the crystal orientation and reveal strain fields. To this end, the excitation polarization is rotated while recording the intensity of the SHG signal component that has the same polarization as the incident light. Polarization series were recorded in a fully automated manner at three positions of the MoS2 flake (lower right picture). The distinct patterns observed indicate different strain levels.

Correlative Raman, PL and SHG imaging yields complementary and consistent information for characterizing single-layer TMD crystals by visualizing features of the crystal structure, such as grain boundaries or strain fields, without damaging the sample.

For more details, including further pictures and references, please download our 2-page application note on correlative high-resolution imaging of MoS2.

Correlative Raman, PL and SHG imaging of a mono-layer MoS2 flake. 200 nm per pixel for all images. For a detailed description and more pictures, please download the attached application note.

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July 2020

Graphene fine structures visualized by high-resolution confocal Raman imaging

Raman imaging is a non-destructive tool for evaluating the quality of 2D materials as strain, doping, defects and layer number can be assessed. These two large-area Raman images visualize defect density (top) and strain fields (bottom) in a CVD-grown graphene flake at high spatial resolution (100 nm per pixel). They were acquired using the fully automated Raman microscope alpha300 apyron equipped with a 532 nm laser for excitation and TrueSurface for focus stabilization.

The upper Raman image is color-coded according to the intensity of the D-band in the recorded Raman spectra. It visualizes crystal defects, as the D-band intensity depends on the defect density in the carbon lattice. The observed width of the fine structures is very close to the diffraction limited lateral resolution achievable with 532 nm excitation, demonstrating the microscope’s high performance.

The lower Raman image is color-coded according to the peak position of the 2D-band, which was quantified by a Pseudo-Voigt fit. The image visualizes local strain/doping effects, as the frequency of the 2D-band is influenced by local strain and, to a lesser extent, by doping.

These examples offer conclusive proof that with an advanced and highly sensitive system, Raman imaging alone can provide access to the finest details of graphene crystal properties.

High-resolution Raman imaging of CVD-grown graphene (100 nm per pixel). Top: Raman image representing the intensity of the D-band, visualizing crystal defects. Bottom: Raman image representing the frequency of the 2D-band, visualizing local strain/doping effects.

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July 2020

ParticleScout is a contender for the Wiley Analytical Science Award 2021

We’re thrilled to share that ParticleScout, our automated microparticle analysis tool, has been chosen as a finalist for the 2021 Wiley Analytical Science Award!

This distinction from a neutral jury of researchers and industry representatives includes ParticleScout among six nominated products in the “Spectroscopy & Microscopy” category. Now, the readers of “GIT Labor-Fachzeitschrift”, “Imaging & Microscopy” and all users of the Wiley Analytical Science Portal can vote for their favorite product on the following page:

http://www.was-award.com/

Voting is possible from July 1st until August 28th. Wish us luck, or even better, voice your support for ParticleScout, the revolutionary tool that uses Raman spectroscopy to characterize microparticles, including microplastics in the environment.

https://www.witec.de/products/accessories/particlescout/

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July 2020

Researchers in India use a WITec Raman microscope to detect RNA viruses

A paper just published in the Journal of Biophotonics describes how Raman spectoscopy can enable the detection of RNA viruses in human saliva. Dr. Amit Dutt's group at the Tata Memorial Centre, based in Mumbai, obtained raw data with a WITec Raman microscope and carried out statistical analysis to find a set of 65 Raman spectral features that positively identified the presence or absence of viruses in a sample.

The analysis could be performed in less than a minute without adding a reagent to increase the signal. Their signal set was able to achieve 92.5% sensitivity and 88.8% specificity.  

“This conceptual framework to detect RNA viruses in saliva could form the basis for field application of Raman Spectroscopy in managing viral outbreaks, such as the ongoing COVID-19 pandemic,” said the researchers.

https://onlinelibrary.wiley.com/doi/abs/10.1002/jbio.202000189

Scientists in the research group of Dr. Amit Dutt, who used Raman microscopy to detect RNA viruses in human saliva samples.

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