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November 2021

WITec and Oxford Logos rendered with lithography and imaged by Raman

This example of nanolithography was created on silicon using a pulsed 532 nm laser. It shows a representation of the Raman effect and the logos of both WITec and parent company Oxford Instruments.

The upper image depicts the integrated intensity of the Si band, while the lower image visualizes the Si peak position shift that occurs when vaporization leaves residual stresses in the adjacent material.

Scan range: 560x360 pixels; 140x90 µm². Excitation: @532 nm; 50 mW. Objective: 100x; NA 0.9

Learn more about our nanolithography capabilities in our Lithography Application Note.

Logos Lithography 504

Raman images of nanolithographed logos. Scan range: 560x360 pixels; 140x90 µm². Excitation: @532 nm; 50 mW. Objective: 100x; NA 0.9

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October 2021

Conference Review: 17th Confocal Raman Imaging Symposium

Ulm, Germany  
October 7, 2021

This year’s Confocal Raman Imaging Symposium, held online, achieved a new level of engagement with a record number of participants from around the world. Over 500 registrants signed up to view and discuss a field of 55 posters grouped under the topics: Advanced Materials Analysis; Environmental and Geo Science; and Life Sciences, Biomedical and Pharma Research. Attendees were treated to five featured talks presented by esteemed researchers, everyone was encouraged to offer ratings that were compiled to determine the winner of the 2021 Best Poster Award, and more than 80 researchers registered to take part in virtual equipment demonstration sessions.

During the one-week virtual Symposium, participants were invited to explore the conference platform and on-demand oral presentations. A good starting point was the thorough introduction to Raman spectroscopy and microscopy provided by Prof. Sebastian Schlücker (University of Duisburg-Essen, Essen, Germany). Prof. Barbara Cavalazzi (University of Bologna, Bologna, Italy) described how she uses 3D Raman imaging in her work on microbial paleontology, including the detection of the oldest fossilized methanogens ever found. Prof. Dominique Lunter (Eberhard Karls University, Tübingen, Germany) shared details of her investigations of skin penetration by pharmaceutical ingredients and the impact of penetration enhancers. WITec’s own Dr. Ute Schmidt covered recent developments in studies of transition metal dichalcogenides and Prof. Laurene Tetard (University of Central Florida, Orlando, USA) presented 3D Raman analyses of thermal barrier coatings in jet engines.

Along with the featured speakers, the 55 contributed posters provided a wealth of scientific content. In the end, one poster received the highest rating from fellow attendees and that honor belongs to Jessica Caldwell from the Adolphe Merkle Institute at the University of Fribourg, Switzerland. She won the Best Poster Award for her contribution: Detection of Various Nanoplastics via Gold Nanoparticle-Based Surface Enhanced Raman Spectroscopy (SERS) Substrates. Together with Patricia Taladriz-Blanco, Barbara Rothen-Rutishauser and Alke Petri-Fink, she explored one of the most resonant topics in contemporary science: the detection of micro- and nanoplastic particles.

Equipment demonstrations had previously been offered onsite in our laboratories on the final day of the Symposium. This year morning and afternoon sessions were hosted online every day of the conference to accommodate over 80 registrants. WITec application scientists showed the instruments in action with demos of confocal Raman imaging, Raman-AFM, topographic Raman imaging, and Raman-based particle analysis coupled to a spectral database.

The 17th Confocal Raman Imaging Symposium flourished in its transition to a virtual event. Given recent disruptions, it was reassuring to see the spectroscopic imaging community persist in convening to share, discuss and celebrate new techniques and discoveries. We look forward to seeing everyone in person again when possible.

The 18th Confocal Raman Imaging Symposium will take place from September 26th – 28th, 2022. Details including the list of invited speakers and reviews of previous symposia can be found on the Confocal Raman Imaging Symposium homepage: www.raman-symposium.com.

BestPosterAward2021 JessicaCaldwell AdolpheMerkleInstitute UniversityOfFribourg NEWS web

Best Poster Award Winner Jessica Caldwell presents the certificate in front of her poster about detecting nanoplastics using gold nanoparticle-based SERS substrates. © Jessica Caldwell, Adolphe Merkle Institute, University of Fribourg, Switzerland.

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September 2021

Raman microscopy detects titanium dioxide in food samples

Titanium dioxide (TiO2) has long been used as a white pigment (E 171) in the food industry. Recently it’s been subject to increased scrutiny due to concerns that it might be carcinogenic. In May 2021, the European Food Safety Authority (EFSA) announced that the substance can no longer be considered a safe food additive (EFSA web news). This led European food manufacturers to replace TiO2 in their products with alternative white pigments.

Raman imaging microscopy is a very effective method for analyzing food additives and TiO2 is especially easy to detect as it exhibits a strong Raman signal. This study is a comparison of the same kind of candy produced for two different markets: the EU and the USA. All of the pieces have a white “S” printed on their colorful coatings (A) and Raman analysis reveals the chemical identities of the pigments used. The measurements were performed with an alpha300 R equipped with a 488 nm excitation laser and TrueSurface technology for topographic Raman imaging and active focus stabilization.

Raman imaging clearly distinguished the print from the surrounding sugar coating in both candies and the topographic Raman images show their curved surfaces (B and C). The white pigments forming the S were identified by their Raman spectra as TiO2 in the USA candy (red in B and D) and calcium carbonate (CaCO3) in the EU candy (blue in C and D). Raman spectroscopy can even differentiate crystal forms of TiO2; The print in the USA candy consists of anatase (B and D).

Skittles News 504 Labels

Raman imaging of candy coatings. Photograph of the investigated candy (A). Topographic Raman images of the print on the candy produced for the USA (B) and the EU (C). The “S” prints are color coded according their Raman spectra (D), revealing that the white pigment is TiO2 in the USA, but CaCO3 in the EU.

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September 2021

WITec Now Officially Part of Oxford Instruments

We are pleased to announce that the final step in the acquisition process of WITec GmbH by Oxford Instruments plc has been concluded. WITec joins the Materials Analysis Group of the UK-based technology company with WITec’s founders Dr. Joachim Koenen and Dr. Olaf Hollricher continuing as Managing Directors. Further details about the acquisition were announced in our press release on June 16, 2021.

Dr. Ian Barkshire, Chief Executive, Oxford Instruments said, “We are delighted to complete the acquisition of WITec and welcome our new colleagues to Oxford Instruments. WITec’s leading Raman microscopy solutions are a great complement to our existing products and techniques. We look forward to growing the business through investment in R&D as well as enabling them to reach new customers through our global sales and service channels, thereby supporting our customers in facilitating a greener economy, achieve increased connectivity, improved health and leaps in scientific understanding.”

“We’re very grateful for the warm welcome we’ve all received from Oxford Instruments,” said Dr. Koenen, WITec co-founder and Managing Director. “Joining Oxford Instruments provides us with greater resources and enables continued growth while also maintaining WITec’s innovative spirit. Now that the formalities are completed, we look forward to working together with the other business units.”

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August 2021

WITec alpha300 apyron wins 2021 Microscopy Today Innovation Award

The fully automated Raman microscope is deemed one of the year’s best developments.

Ulm, Germany
August 2, 2021

WITec GmbH, the prime mover of technological advance in commercial Raman microscopes, has received a 2021 Microscopy Today Innovation Award for its alpha300 apyron fully automated Raman imaging system.

It was selected by the editors of Microscopy Today as one of the ten most significant innovations in the areas of light microscopy, electron microscopy, and microanalysis. As described by the award organizers, “These innovations will make microscopy and microanalysis more powerful, more productive, and easier to accomplish.”

The alpha300 apyron delivers the full benefits of 3D Raman imaging at the click of a mouse, to researchers of all experience levels. Motorized components and software-driven routines enable self-optimization to accelerate experimental setup for increased sample turnover rates and to ensure the consistency of results. It is also capable of remote operation, in environmental enclosures such as glove boxes and even from home offices.

“We’re very honored to receive the 2021 Innovation Award,” said Harald Fischer, Marketing Director at WITec. “Microscopy Today is such an esteemed publication and they really understand what matters to the people in the labs, using the instruments. The alpha300 apyron brings all our know-how in optics, mechanics and software together so it’s great to have that recognized.”

For further details, please visit the alpha300 apyron product page.

MT IA News

The Innovation Award-winning alpha300 apyron

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July 2021

17th Confocal Raman Imaging Symposium Goes Virtual

Europe’s foremost molecular characterization conference will be held online.

Ulm, Germany
July 29, 2021

WITec GmbH, the technology leader in Raman microscopy solutions, has re-envisioned the Confocal Raman Imaging Symposium as a virtual event for its 17th year. This scientific conference has become highly regarded within the international chemical imaging community for its amiable atmosphere, compelling presentations and the range of research on display in its poster sessions.

With the enthusiastic reception to last year's Virtual Raman Imaging Poster Summit, and the ongoing complications regarding travel, the decision was made to adopt the online format for this year's event. With an established platform the 17th Confocal Raman Imaging Symposium will preserve both the scientific depth and variety characteristic of previous symposia with the convenience of worldwide distributed participation.

The Confocal Raman Imaging Symposium will take place from September 27th through October 1st, 2021. Invited speakers from pertinent fields of application will deliver presentations that can be viewed on demand throughout the week of the conference. The scientific poster sessions will be grouped into three categories: Advanced Materials Analysis, Environmental and Geo Science and Life Sciences, Biomedical and Pharma Research. Online equipment demonstrations will also be offered so that researchers can experience the latest Raman microscopy innovations in action.

Registration is now open and free of charge. Participants can look forward to seeing the current state of the art in confocal Raman imaging techniques and applications while interacting online with speakers and fellow attendees through the platform’s chat function. Details including the list of invited speakers, reviews of previous symposia, and registration information can be found on the Confocal Raman Imaging Symposium homepage: https://www.raman-symposium.com/

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July 2021

WITec and attocube launch cryoRaman

Technology leaders combine expertise for very low-temperature Raman imaging

Ulm, Germany - Haar, Germany
July 20, 2021

Raman imaging innovator WITec GmbH and cryogenic microscopy specialist attocube systems AG have jointly introduced cryoRaman. This cryogenic Raman imaging system integrates attocube’s leading-edge cryostat and nanopositioner technology with the vaunted sensitivity and modularity of WITec’s alpha300 correlative microscope series. For the first time, Raman imaging at the lowest temperatures in high magnetic fields is now easily accessible with unmatched spatial resolution.

Designed to meet existing and emerging challenges, cryoRaman offers excitation wavelengths from VIS to NIR with optimized spectrometers, 1.6K to 300K operating temperatures, high magnetic fields, patented cryogenic Raman-specific objectives and an exceptionally precise piezoelectric scan stage.

“We’ve seen interest in cryogenic Raman grow rapidly and expand beyond the initial core of graphene and carbon nanotube research groups,” said Florian Otto, Head of Business Sector Cryogenic Instruments at attocube. “We decided together with WITec to address the broadened user base’s increasingly varied experimental requirements. cryoRaman is the successful realization of that effort to redefine low-temperature chemical characterization in terms of user-friendliness, flexibility and outright capability.”

Research on phase-transitions and emergent properties of novel low-dimensional materials will benefit in particular from cryoRaman’s high magnetic field options. The solenoid or vector magnets, with a strength of up to 12T, are ideal for investigating transition metal dichalcogenides (TMDs) and van der Waals heterostructures, and can also help in determining the temperature- and magnetic field-dependence of photoluminescence. Optional modules include precise software-controlled laser power adjustment, multi-wavelength excitation capabilities, automated switching from optical microscopy to spectroscopic imaging, automated spectrometer calibration light source and routines, and time-correlated single photon counting (TCSPC) modes.

cryoRaman also introduces a pair of unique functionalities to cryogenic Raman microscopy: the ability to detect low-wavenumber Raman peaks, and full polarization control in excitation and detection. “Researchers looking at materials in cryogenic environments like to get as close as possible to the excitation wavelength, and they’re very interested in polarization measurements,” said Olaf Hollricher, Co-founder and Managing Director at WITec. “To meet those requirements, we developed features that have no equivalent in the marketplace. In fact, with its imaging capability at low temperatures, level of integration, performance and accessibility to both Raman newcomers and experts, cryoRaman is really in a class by itself.”

The close cooperation between attocube and WITec has produced an instrument ready for an unprecedented range of measurements. cryoRaman incorporates the very latest technology from two trailblazers in their respective fields to establish cryogenic Raman microscopy as a convenient, versatile and indispensable tool for materials scientists.

For more information and a detailed application note, please visit our cryoRaman product page

About WITec

WITec GmbH pioneered 3D Raman imaging and correlative microscopy and continues to lead the industry with a product portfolio that offers speed, sensitivity and resolution without compromise. Raman, AFM and SNOM microscopes, combinations thereof, and WITec-developed Raman-SEM (RISE) systems can be configured for specific challenges in chemical and structural characterization through a modular hardware and software architecture with built-in capacity for expansion. Research, development and production are located at WITec headquarters in Ulm, Germany, and the WITec sales and support network has an established presence in every global region.

About attocube

attocube systems AG is a leading pioneer for nanotechnology solutions in industry and research. The company develops, produces and distributes components and systems for nanoscale applications such as precision motion, cryogenic microscopy, and nanoscale analytics. All products are manufactured in the NanoFactory, the company’s headquarters in Haar, close to Munich. An international team of 200 physicists, engineers, software developers, and product designers work in close collaboration from conception through to delivery. attocube has sales offices in the US and a broad network of worldwide distributors, covering more than 40 countries and 4,000 customers.

cryoRaman News 2

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June 2021

Photon antibunching identifies single-photon emitters

WITec combines antibunching experiments with fast Raman and photoluminescence imaging.

Single-photon emitters have quantum mechanical properties that are exploited in quantum technology and information science, including the development of quantum computers and cryptography methods. Nitrogen vacancy (NV) centers in diamonds, single fluorescent molecules, carbon nanotubes and quantum dots are prominent examples of single-photon emitters. In order to identify them in a sample, antibunching experiments are commonly performed.

Antibunching is a quantum mechanical effect that reveals the particle-like behavior of light. It arises because a single-photon emitter can only emit one photon at a time. The minimum interval between photon emissions depends primarily on the excited-state lifetime of the emitter, because a cycle of excitation and relaxation must be completed between two photons. If the signal is split and measured with two detectors, each single photon can only be detected by one of them. Antibunching therefore results in an anticorrelation of the two detectors’ signals at very short lag times (Hanbury Brown-Twiss experiment).

Here WITec in cooperation with PicoQuant demonstrates the integration of antibunching measurements within a confocal Raman microscope. This combination makes it possible to characterize a sample with fast Raman and photoluminescence (PL) imaging and identify areas of interest for subsequent antibunching experiments with the same instrument, a WITec alpha300 Raman microscope. Antibunching measurements are performed in a Hanbury Brown-Twiss configuration, where the signal is split by a 50/50 beam splitter and detected by two APDs. Both detectors are connected to a MultiHarp 150 time-correlated single photon counting (TCSPC) unit from PicoQuant, which records the delay between two single-photon events at picosecond resolution. A histogram of the time differences shows a pronounced dip for very short times, i.e. antibunching, if the investigated structure is a single-photon emitter. Lifetime measurements are additionally possible in this configuration. A 532 nm continuous wave laser was applied for excitation here, but the setup also supports other wavelengths and pulsed laser sources.

We demonstrate this functionality using a sample of diamond micropillars, a fraction of which contain single NV centers. The sample was provided courtesy of Dr. Rainer Stöhr and Prof. Dr. Jörg Wrachtrup from the 3rd Physics Institute at the University of Stuttgart, Germany.

The pillars were first imaged with Raman and PL microscopy. The Raman image represents the intensity of the diamond peak at 1330 cm-1 and reveals the positions of intact pillars (Fig. A). In the fluorescence image, some pillars are particularly bright, indicating the presence of NV centers (Fig. B). By comparing the Raman and PL images, structures of interest can be distinguished from fluorescent contaminations on the sample: intact pillars with NV centers exhibit a strong diamond Raman signal and bright fluorescence (arrows in Fig. A and B), while contaminations lack the Raman signal.

Antibunching experiments were performed at some of the identified structures of interest in order to test for the presence of single NV centers. The resulting correlation curve for one selected pillar is displayed in Fig. C. The histogram has a pronounced dip at a detection time difference of zero. This indicates that the observed micropillar indeed contained a single NV center and was a single-photon emitter. The observed drop in the curve toward longer delay times reveals the presence of a shelving state, which is a well-known phenomenon for diamond NV centers.

The integration of antibunching experiments within a confocal Raman microscope offers many benefits. Such an instrument is capable of carrying out both spatially resolved chemical characterization and quantum mechanical investigations. As demonstrated here, the correlation of Raman and photoluminescence signals can pre-select candidate locations for NV centers to be subsequently confirmed by antibunching experiments. This provides valuable insight and an accelerated workflow to researchers exploring single photon emitters for use in emerging technologies, including quantum computers.

Antibunching NVcenter web

Identifying single-photon emitters in diamond micropillars containing NV centers. A: Raman intensity image of the diamond line (1330 cm-1). Bright spots represent intact diamond micropillars. B: Fluorescence intensity image of the same area. Bright spots originate from NV centers and fluorescent contaminations. Micropillars with NV centers show both Raman and fluorescence signal (arrows). C: Photon antibunching curve from one NV center. The pronounced dip in the histogram at zero time difference indicates the presence of a single emitter. Sample courtesy of Dr. Rainer Stöhr and Prof. Dr. Jörg Wrachtrup from the 3rd Physics Institute at the University of Stuttgart, Germany.

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June 2021

WITec GmbH joins Oxford Instruments plc

The management team of WITec GmbH is proud to announce that WITec was acquired by Oxford Instruments plc, a UK based company that has a great reputation in the scientific community, and in the future will be part of their Materials Analysis Group. WITec’s founders Dr. Joachim Koenen and Dr. Olaf Hollricher will continue as Managing Directors and the well-established WITec brand will be retained in the new organizational structure.

Founded in 1997, WITec grew from a small university spin-off into the most innovative Raman imaging company. It made exceptional progress in developing microscopy technology and installed more than a thousand Raman, AFM and SNOM systems worldwide.

“We look back on a 24-year track record of making WITec a prosperous and most innovative Raman imaging company. Now that we are joining the Oxford Instruments Group, we look forward to continuing this success together with a strong partner to grow even faster and to use existing synergies to further expand our reach into the range of markets that will benefit from our wide product portfolio,” Koenen said.

“WITec developed ground-breaking solutions in confocal Raman microscopy and correlative Raman microscopy. Oxford Instruments’ key technologies in AFM and scientific spectroscopic cameras with the brands Asylum and Andor puts WITec in an even better position for future developments,” Hollricher added.

Ian Barkshire, Chief Executive, Oxford Instruments said, “We are delighted to welcome WITec colleagues to Oxford Instruments. WITec’s leading Raman microscopy solutions are a great complement to our existing products and techniques. Raman microscopy is an important and widely used technique across academic and commercial customers for fundamental research, applied R&D and QA/QC. The technique is used in conjunction with and alongside our existing characterization solutions and broadens the capabilities that we can bring to existing customers and expands opportunities into new market areas. Providing a broader range of solutions helps us support our customers in facilitating a greener economy, increasing connectivity, improving health and achieving leaps in scientific understanding.”

Ian Wilcock, Managing Director of Oxford Instruments Nanoanalysis and Magnetic Resonance added, “We look forward to working with our new colleagues at WITec to develop new routes to market for their products. WITec’s RISE Raman for SEM product, for example, will ideally complement our own extensive suite of analyzers for electron microscopes.”

WITec will, of course, fulfill its obligations toward existing customers and business partners in the usual manner and the management team will work to make the transition as smooth as possible.

See the official press release from Oxford Instruments here.


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The companies’ representatives following the official announcement at WITec Headquarters in Ulm, Germany. From left to right: Joachim Koenen (Managing Director at WITec), Alexandra Lipes (HR Generalist at Oxford Instruments), Dirk Keune (Managing Director Germany and Director Sales EMEAI at Oxford Instruments) and Olaf Hollricher (Managing Director at WITec).

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June 2021

Observing polymerization reactions with Raman microscopy

Polymerization reactions are involved in many industrial processes and also occur in everyday tasks, for example during the hardening of glues and drying of paints and varnishes. In order to optimize their products, manufacturers require analytical methods for monitoring polymerization reactions and evaluating the influence of chemical modifications or additives such as catalysts. Here we use Raman imaging for monitoring the polymerization of an air-drying alkyd resin varnish. Such products are commonly used for protective coating of wood and other materials.

The liquid sample was applied to a microscope slide and the polymerization progress was characterized as a function of depth and time using a WITec alpha300 Raman microscope. To this end, an initial depth scan through the entire coating layer was recorded, followed by one per hour at the same sample position for a total of 25. Due to the system’s automated components, no user interaction was required during the entire investigation time of 24 hours. Each of the presented Raman images covers an area of 25 x 31 µm² and consists of 3900 spectra recorded in about 8 minutes.

First, all images were analyzed with the TrueComponent Analysis feature of the WITec Project software. Three components were identified by their Raman spectra and attributed to the liquid varnish, the polymerized product and the glass substrate. The image series clearly shows that the hardening process began at the interface between the air and the varnish and progressed through the sample over time (Fig. A and video). After 24 hours, the sample was almost completely hardened. A small stretch of unpolymerized sample was still present at the glass interface after 24 hours, but was no longer detectable when the sample was re-measured a few weeks later.

The spectra of liquid and solid varnish differed mainly in the intensity of the C=C stretching mode at 1654 cm-1 wavenumbers (Fig. B). As the C=C double bonds react during the polymerization, this peak’s intensity is drastically reduced in the Raman spectrum of the product. This enabled an even more detailed monitoring of the polymerization reaction. While the C=C stretching mode was decreased during the reaction, the C-H stretching mode (ca. 3072 cm-1) stayed almost constant. The ratio of these two peaks thus served as a measure for the polymerization progress. It was quantified for each pixel by peak fitting and the mean of each image line was plotted over the sample depth and the observation time (Fig. C). The graph illustrates in detail how the polymerization progresses over time into the deeper layers of the varnish.

For more examples for Raman imaging of polymers, visit our applications section about polymers or download our Application Note about polymeric materials.

Alkydharz WebNews

Polymerization reaction of an alkyd resin varnish monitored over 24 hours. 2D Raman depth scans at different times after the reaction start (A), color coded according to the Raman spectra (B) of liquid varnish (red), polymerized product (blue) and glass substrate (green). Polymerization progress versus depth and time (C). See text for more details.

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