alphaCART is WITec’s mobile, confocal Raman system for all applications that require bringing the lab to the sample.
alphaCART’s Raman probe can be flexibly positioned in front of bulky, immovable or precious objects that can’t be transported to a microscope or that don’t fit under one.
The system's high confocality and signal sensitivity also allow measurements through protective glass and windows, which enables studies of gases or chemical processes inside reaction chambers and other enclosures. Researchers working in the arts and archaeology, geo- or materials science will especially benefit from this versatile and powerful analytical tool.
alphaCART: Freely positionable, fiber-coupled, confocal Raman system
The alphaCART system leverages the advanced optics and modular design of WITec’s established alpha300 series Raman microscopes and profits from WITec’s longstanding expertise in fiber coupling technology. Laser, probe and spectrometer are connected through optical fibers, ensuring the highest signal throughput and optimal beam shape. Thus, alphaCART provides the same diffraction-limited spatial resolution and confocality and superior signal sensitivity as all WITec alpha300 systems.
alphaCART is available in different configurations to meet your specific requirements regarding excitation wavelength and spectrometer set-up. For detailed sample survey, white-light illumination and a color video camera are available. Data acquisition and post-processing are controlled through the latest WITec Software Suite.
The complete stand-alone alphaCART system is bundled into a compact rolling flight case for easy and safe transport to experiments in the field. Additionally, the Raman probe can be connected to a stationary alpha300 microscope to extend its flexibility within a lab.
Research-grade Raman microspectroscopy goes mobile
Key Features
Freely positionable, fiber-coupled Raman probe
High spectral and spatial resolution, confocality and signal sensitivity
Sample survey with white-light illumination and color video camera
Objective, laser and spectrometer configuration options
Rolling flight case containing and protecting all components (optional)
Advanced data post-processing
Polarization-sensitive measurements (optional)
Full compatibility with alpha300 series upgrades and accessories
Benefits
The positioning flexibility of the alphaCART probe combined with its high confocality and signal sensitivity enables the nondestructive analysis of:
Oversized samples that don’t fit under a microscope
Fragile or precious objects that can’t be moved to a lab
Samples that exhibit fluorescence, as background is minimized
Inclusions in various materials
Processes inside reaction chambers
Gases and liquids inside glass containers, as even weak signals can be detected
Samples at high temperature, as background from black body radiation is effectively minimized
Flexible positioning
alphaCART Raman probe positioned in front of a framed picture. The white-light illumination allows for the recording of a survey image. The probe’s confocality and sensitivity enable high-quality Raman measurements of the painting through the protective glass.
Specifications
Laser, probe and spectrometer coupled by optical fibers for high signal throughput and optimal beam shape
Rolling flight case containing and protecting all components (ca. 100x60x60 cm) (optional)
High spatial resolution and confocality (diffraction-limited)
High spectral resolution over full spectral range (from ca. 90 to 3500 cm-1, depending on excitation wavelength)
Data acquisition and post-processing with latest WITec Software Suite (including time-series, advanced background subtraction algorithms and more)
Laptop with Microsoft Windows™ 11 operating system included
Application Areas
Arts and Archeology
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Geo Science
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Materials Science
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Gas Science
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Application Examples
alphaCART’s high confocality and sensitivity enable Raman analyses of fluorescing materials and weak Raman scatterers, even if the sample is behind protective glass or inside an enclosure.
For illustration, the Raman probe was positioned in front of a framed poster showing a portrait of Sir C. V. Raman. Using the alphaCART’s white-light illumination and video camera, a part of the poster was magnified, showing differently colored ink spots. The raw Raman data recorded at different positions with a 532 nm laser was partially obscured by the high fluorescence background from the paint. However, applying efficient background subtraction algorithms included in the WITec Project software revealed the Raman spectra of the various pigments and of the coated paper. Due to the system’s high confocality, the protective glass in front of the poster remained outside of the focal plane of the measurement, reducing the fluorescence background and enabling the detection of the Raman signals.
Raman analysis of a poster through protective glass. The white-light illumination and camera showed ink spots in different colors. Initially, the Raman spectra recorded at the indicated positions with a 532 nm laser were partially obscured by a high background, but they were subsequently revealed through background subtraction.
Nondestructive characterization of art and historic objects
Being a portable system, alphaCART can be used for investigating objects that can’t be moved into a lab. A WITec Raman probe was brought to the Kunsthistorisches Museum in Vienna, Austria, to conduct the most thorough analysis to date of the Imperial Crown of the Holy Roman Empire.
Raman and photoluminescence measurements of the Imperial Crown’s 172 gemstones were performed in the Imperial Treasury in Vienna by researchers from the Institute of Mineralogy and Crystallography at the University of Vienna. The study provided detailed insights into this historic treasure, which were published in the Journal of Gemmology (DOI: 10.15506/JoG.2023.38.5.448).
Further information about this unique project can be found in the following articles:
L. Nasdala et al. (2023) The Imperial Crown of the Holy Roman Empire, Part I: Photoluminescence and Raman Spectroscopic Study of the Gemstones. The Journal of Gemmology38: 448-473. (DOI: 10.15506/JoG.2023.38.5.448)
Materials science: In situ observation of diamond coating
alphaCART is ideally suited to monitoring chemical processes inside reaction chambers. In this example, the diamond coating of a steel tool was observed in situ through the window of a hot-filament chemical vapor deposition (HF-CVD) reactor. The probe was equipped with a long working distance objective. Its high sensitivity and confocality enabled the detection of the relatively weak Raman signals from the thin diamond layer despite the black-body radiation of the hot sample.
Diamond coatings are applied to many machine tools and mechanical components for their hardness, chemical inertness and wear resistance. In situ chemical characterization of the material is beneficial for optimizing production methods, for example, to minimize stress in the finished tool. By positioning the alphaCART Raman probe in front of the HF-CVD reactor, temperature-dependent Raman spectra could be obtained from the diamond material during the entire coating and subsequent cooling process. From the Raman spectra, the temperature-dependent sp3 peak positions (around ca. 1330 cm-1) were quantified. After subtracting the temperature-dependent Raman shift, thermal stress and the quality of the diamond layer could be determined and conclusions were drawn about crystallographic modifications in the steel substrate.
alphaCART Raman probe positioned in front of a window in the HF-CVD reactor for in situ monitoring of the processes of diamond coating and cooling.
Raman spectra, normalized after background subtraction, of the diamond coating at the beginning (870°C, red) and the end of the cooling process (30°C, blue). The result of a Lorentzian fit for determining the position of the sp3 peak is overlaid on the measured spectra.
Data courtesy of Thomas Helmreich, Maximilian Göltz, Stefan M. Rosiwal, Chair of Materials Science and Engineering for Metals (WTM), Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Germany.
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