Raman Spectroscopy Expands Its Scope

With improvements in instrumentation, Raman spectroscopy continues to expand its range of applications to diverse areas of materials analysis and research. Participants in this Raman Tech Forum are Robert Chimenti of B&W Tek, Andrew Whitley of Horiba Scientific, Ryan Kershner of Thermo Fisher Scientific, and Harald Fischer of WITec.

What are the most important new applications for Raman spectroscopy? Which areas are showing the most growth? (For example, carbon nanotubes, graphene, and medical applications.)

Chimenti: All three of the applications listed above are important, but the one that has the most potential to revolutionize the world is, without a doubt, the increasing research and development around biomedical applications of Raman spectroscopy. Raman spectroscopy for biomedical diagnostics has the potential to facilitate the most widespread deployment of Raman spectroscopy to date. Cutting-edge research is now being conducted by groups all around the world; for example, the ground-breaking work being performed by Dr. Marc Porter and his team of scientists at the University of Utah where they are developing surface-enhanced Raman spectroscopy (SERS) as a bioassay platform.

Whitley: The potential for Raman microscopy in biological sciences is huge. Raman is seen as a powerful new characterization method for disease diagnosis, cell screening, protein investigations, and so forth. The techniques are still in the early adopter phase but we should see steady and then quick growth in this field over the next decade. As we all know, certain industries that have used Raman extensively over the years like pharmaceuticals are in a bit of a depression at the moment, and the spending on spectroscopy is certainly down in these industries. However, there are new heavily funded areas like energy research and discovery that are quickly realizing how much Raman has to offer.

Kershner: We continue to see Raman for applied research in nanomaterials development, including thin film applications and integrated devices. There has been a notable increase in Raman for end-use applications, particularly in the areas of graphene and other novel two-dimensional materials. We are also seeing major activity on the industrial side as nanoscale composites gain traction in the marketplace, integrating nanotubes, nanoparticles, and other zero- and one-dimensional structures in ways that have not been witnessed before. Quality, homogeneity, structure-property relationships — there's a wealth of information that Raman can provide, and this is really starting to be embraced at the production level.

Fischer: The latest achievements in the field of nanotube and graphene research leading to nanoelectronic devices based on carbon materials are certainly a significant advancement and with Raman delivering important information on the properties of such materials we anticipate strong and sustained demand for Raman instrumentation in the field of nanocarbon research. Biomedical, pharmaceutical, and life science in particular show huge potential for further growth.

How have recent developments in Raman instrumentation affected the range of uses for the technique?

Chimenti: Today’s Raman instrumentation is faster, more rugged, and less expensive than previous instrumentation. Now, with the advances in component miniaturization, the design of high performance portable and handheld devices has introduced the technology to new application areas that were previously not possible with older, more cumbersome instruments. These recent developments have created units that are much smaller in size but do not sacrifice performance.

Whitley: We see three major areas of important development for laboratory based Raman systems: Simplification of operation through automation and powerful software is allowing the power of Raman to be easily deployed by many more users; the continued advancement of rapid Raman imaging so that even Raman survey scanning of samples is possible; and the combination of Raman with other sampling and measurement techniques — for example, atomic force microscopy (AFM)–Raman, scanning electron microscopy (SEM)–Raman allowing visualization and measurement of the nanoworld, Raman combined with complete microscopy (both upright and inverted microscopes), and Raman combined with particle location and positioning tools to provide automated characterization and even sorting of particles and cells.

Kershner: Besides the obvious advances in technology (more sensitive detectors, more powerful lasers with improved stability), the real benefit has come from systems that are designed for ease-of-use. Gone are the days of complicated and lengthy setup and configuration for a specific experiment. The latest instruments allow users to walk up and get immediate results with minimal training and experience. These are not your grandfather's Raman microscopes. The benefits are clear: Organizations that once required dedicated personnel for the care, maintenance, and training associated with more traditional Raman instruments have been able to apply their savings to increased productivity. This also translates into the ability to expand the range of applicable samples, giving even the least experienced of users more flexibility to focus on exploring how the Raman technique can be applied in new and exciting ways. Multiuser shared facilities at major research universities are a perfect example. A single Raman instrument might see tens or even hundreds of users, each with a unique application. Our goal as instrument designers should be to enable every user to get rapid answers to their research questions, permitting more agile changes in research direction that keep pace with how quickly users' work evolves.

Fischer: While a few years ago the main purpose of a benchtop Raman instrument was to acquire single spectra or spectral maps on the macro- or microscopic scale, today the prevailing 3D Raman imaging system offers accurate and detailed insights regarding the chemical composition of a sample. This extends the application area from chemically identifying to imaging the compounds of a sample at the highest spatial resolution. The ongoing trend of miniaturization and the breakthrough in handheld instruments for mobile applications in QA or field studies has also caught the attention of the Raman users.

What lies in the future for Raman spectroscopy? What are the opportunities for innovation with the technique and instrumentation?

Chimenti: Future improvements to Raman spectroscopy will be heavily focused on developing smarter, more intuitive, and overall user-friendly software. Not only will there be improvements in signal processing, method development, and chemometric analysis, but the next generation of spectrometers will also make it so that anyone can easily perform these functions without the need for advanced training. Incremental hardware advancements will continue to pave the way for these software improvements. All of these improvements will increase the adoption rate of Raman spectroscopy, which will inevitably drive down the cost, allowing for greater accessibility in applications that were never before thought possible with Raman spectroscopy.

Whitley: Novel sampling and software integration will bring Raman in to areas not possible before. Allowing new industries to first develop methods using Raman spectroscopy followed by deployment on a large scale to continue the double digit growth of Raman spectroscopy. Remember Raman is the see-it spectroscopy — we use visible light so getting the excitation light to the sample and the Raman light back to the spectrometer is relatively easy and certainly much easier than many other techniques. This allows simplified and powerful sampling methodologies not possible with other techniques. Of course as the price decrease and simplification of Raman continues it will continue catch Raman’s sister technique of FT-IR in dollar sales – more and more people are starting to realize that Raman in a growing majority of areas offers so much more than FT-IR.

Kershner: I think we'll see the same trends continuing. Raman spectroscopy will continue to become more mainstream, moving more towards application as a primary characterization tool. Raman instruments will be increasingly viewed as essential for materials development, production and process monitoring. Along with this will be a greater emphasis on systems that provide complete solutions. Software will become even easier to use, and users will expect even more flexibility out of their systems. We're really still on a growth trajectory for the technique as a whole as we continue to realize new, exciting applications — the future of Raman remains bright!

Fischer: There will still be further improvements in sensitivity along with new developments in detector technology. Another element of successful instruments will be an improved ease-of use and user-friendly data evaluation for automated post-processing of the Raman spectral data.

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