TECH FOCUS RAMAN SPECTROSCOPY
What’s the frequency?
A look at the current market for Raman spectroscopy and some of the products and solutions available
R
aman 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.
34 Electro Optics May 2022
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 AvaSoft- Raman 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.
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