Tech focus: Raman spectroscopy

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A look at the current market for Raman spectroscopy and some of the products and solutions available

Raman spectroscopy is a spectroscopic technique most often used to determine vibrational modes of molecules. It is commonly used in chemical applications to provide a structural fingerprint by which molecules can be identified. 

Raman spectroscopy uses a light scattering technique, where a molecule scatters incident light from a high-intensity light source. This is most often from a laser in the visible, near infrared, or near ultraviolet range, but it is also possible to use X-rays. The light interacts with molecular vibrations, phonons or other excitations in the system, causing the energy of the laser photons to be shifted up or down. 

This shift provides information about the vibrational modes in the system. Most of the scattered light is at the same wavelength as the light source and does not provide useful information, but around 0.0000001 per cent is scattered at different wavelengths, depending on the chemical structure, and this is known as Raman scatter. 

Traditionally, photomultipliers were used for dispersive Raman setups, but many found that this meant long acquisition times. Developments in modern instrumentation led to notch or edge filters being used for laser rejection. Dispersive single-stage spectrographs (axial transmissive (AT) or Czerny–Turner (CT) monochromators paired with CCD detectors have become common, alongside Fourier transform (FT) spectrometers for use with NIR lasers. 

According to Stellar Market Research’s latest Raman spectroscopy market report, the market for Raman spectroscopy is predicted to reach $996.92m by 2027, at a compound annual growth rate (CAGR) of 7.6 per cent. 

 

Pro-Lite Technology: featured product

High performance Raman; reproducible SERS

Raman spectroscopy is a powerful analytical technique – combining high selectivity, speed and ease of use – yet Raman scattering is an inherently low-signal effect. The measurement of low concentration solutions, such as the trace detection of drugs, remains a challenge for this spectroscopic technique, but a signal enhancement technique exists. 

Surface enhanced Raman spectroscopy (SERS) uses nanoscale metal structures to significantly amplify the electric field of the laser, resulting in some 1,000 times increase in the Raman signal. Current implementation of SERS has, however, presented either a difficulty in sample preparation or spatial inhomogeneities, resulting in low signal reproducibility. 

Wasatch Photonics and Nikalyte recently announced a partnership to facilitate evaluation and testing of a novel SERS substrate manufactured using Nikalyte’s vacuum nanoparticle deposition technique, resulting in ultra-pure and highly uniformly distributed nanoparticles, free of contamination and easy to prepare. 

Contact us and discover how Wasatch Raman spectrometers make trace detection and identification of materials using Raman a viable technique for use in the laboratory, the field and the clinic. Find out more at: https://wasatchphotonics.com/applications/novel-sers-substrate/

 

Commercial products

Vendors of products and solutions for Raman spectroscopy include Agilent Technologies. The company develops technologies and products for Raman spectroscopy that have been supplied for applications in airport security, hazardous chemical identification and pharmaceutical quality control. 

APE Angewandte Physik und Elektronik offers the picoEmerald system, which facilitates stimulated Raman scattering (SRS) microscopy. It allows simple spectroscopic identification of the samples’ fingerprint region based on Raman spectra databases. Imaging at high video rates is possible due to short integration times of the SRS detection module (lock-in amplifier). 

Available from Avantes is the AvaRaman range, which combines its AvaSpec range of spectrometers with a 532nm or 785nm laser. The spectrometers are appropriately configured according to the wavelength of the laser. The power of the laser source is adjustable via software. AvaRaman systems are equipped with cooling systems and delivered with AvaSoftRaman software. 

B&W Tek has two lines of handheld Raman spectrometers: TacticID and NanoRam. TacticID is specifically geared toward unknown material identification in the safety and security field, where users are encountering unknown substances they need to identify for personal and public safety reasons. NanoRam is designed for pharmaceutical users, offering 21 CFR part 11 compliance and giving users the ability to identify incoming raw materials, as well as finished dosage products.

CNI Laser offers combined Raman spectroscopy systems. The range includes portable Raman spectrometers and a micro Raman spectrum measurement system. The available wavelengths are 405nm, 532nm, 785nm and 830nm. 

Cobolt offers a broad range of compact lasers that are suited to high-resolution Raman spectroscopy applications. Stable single-frequency operation combined with the robust thermomechanical architecture of HTCure provides narrow linewidths over a large range of operating temperatures, low spectral drift and a spectral purity guaranteed better than 80dB. 

Coherent supports Raman spectroscopy and imaging with narrow-line lasers across the entire visible spectrum, with output power from milliwatts to Watts. The ThZ Raman range includes both integrated and modular systems to help access structural information only found in the low frequency region of Raman; to easily identify polymorphic forms or quantify the degree of crystallinity of materials.

The RM5 from Delta Photonics is a compact and fully automated Raman microscope for analytical and research purposes. It is designed to be truly confocal, with variable slit and multiple position-adjustable pinhole for higher image definition, better fluorescence rejection and application optimisation. 

Horiba Scientific has more than 50 years of experience in Raman. The company provides complete Raman spectroscopy solutions for analytical measurements, research Raman, UV Raman, QC/QA and industrial Raman applications. These include Raman spectrometers, hybrid Raman systems (such as AFMRaman), modular Raman systems, transmission Raman analysers, dedicated in-situ process Raman spectrometers, and miniaturised Raman instruments for high volume OEM manufacturers. 

Integrated Optics supplies continuous-wave (CW), single-longitudinal mode (SLM) lasers with all the most frequently used wavelengths for Raman spectroscopy: 405nm, 488nm, 532nm, 633nm, 785nm, 830nm, 1030nm and 1064nm. 

Klar Scientific’s instruments target scientists and engineers with more modest budgets, whose primary interest is in photoluminescence but who occasionally need to make a Raman measurement as well. The company provides a Raman spectroscopy kit at 532nm, which includes a powerful laser and more sensitive spectrometer. For users whose needs span multiple types of spectroscopy, Klar’s reconfigurable, modular instruments can be a cost-effective solution. 

Laser Quantum manufactures suitable lasers for Raman spectroscopy, including 473, 532, 660 and 671nm wavelengths. The Gem family is ideal for OEM integration, whilst Ventus lasers are better suited to scientific and research applications. 

Nanobase provides total solutions for Raman spectroscopy research and other material analysis techniques. Its product range includes the XperRF hybrid micro Raman instrument, XperRAM S and C series of micro Raman instruments and XperRAM M series of macro Raman instruments. 

Ocean Insight offers modular systems, bundled setups and custom solutions for Raman analysis of solids, liquids and gases. Products include the QE Pro series and Ocean HDX series of Ramam spectrometers. The NS200 Raman spectrometer from QS Lasers is a personal benchtop Raman spectrometer that has been designed considering the experimental convenience, integrated with the optical imaging microscope to see the target sample. It is a compact, turn-key Raman spectrometer system including laser, spectrometer and CCD in a compact rugged base module. 

RPMC Lasers offers a wide range of wavelength-stabilised and single-frequency laser sources for Raman spectroscopy. Additionally, a wide range of pulsed laser sources are available for coherent Raman spectroscopy, such as SRS and CARS. 

Toptica Photonics offers several products fulfilling the requirements of Raman spectroscopy, particularly newer applications that require pulsed laser sources operating in the femto- and picosecond regime. Its FemtoFiber laser family is widely used in various broadband CARS and SRS applications. 

Wavelength Electronics supplies a number of components necessary for ultra-stable laser output when using Raman spectroscopy. Providing up to 3A of current with 200 ppm stability, the WLD3343 laser diode driver delivers the well-defi ned current required. Pairing this current source with the WTC3243 temperature controller ensures the operating temperature of the laser stays consistent, minimising the eff ect that temperature fluctuations have on laser wavelength. 

Wasatch Photonics manufactures high throughput UV-VIS-NIR spectrometers. The company says that the f/1.3 fibre coupled spectrometers have 10 times more throughput compared to rival f/4 spectrometers and are ideal for the characteristically weak signals involved in Raman spectroscopy. Solutions include Raman spectrometer systems with integrated laser, modular Raman spectrometers, OEM spectrometer units and Raman probes. Wasatch Photonics Raman spectrometers and spectroscopy systems are available via distribution partner, Pro-Lite Technology.  

This is not an exhaustive list. If you provide products and solutions for Raman spectroscopy and would like your company included, please let us know at: editor.electro@europascience.com 

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13 July 2022