Raman Spectroscopy

Determining the quality of the food we consume is important not just for reasons of safety, but for verifying authenticity as well. Changmou Xu, a Research Associate Professor at the University of Nebraska-Lincoln (UNL), and his colleagues have been exploring methods for food analysis that are rapid but do not harm the environment or the analysts.

As global food supplies and security have been challenged by water scarcity and climate variations, the expected increase in food demand will require a corresponding increase in crop productivity and disruptive improvements in agricultural production systems, including implementing strategies to mitigate the degradation of crop yield caused by plant diseases. Several groups have explored the use of Raman spectroscopy for rapid diagnosis of such diseases.

Raman spectra can help determine protein structure. Here’s how.

The Covid-19 pandemic has led to extraordinary developments of both testing methods and vaccines. Can spectroscopy play a role in next-generation testing for Covid and other pathogens?

A multiscale convolutional neural network (MsCNN) was used to screen Raman spectra of the hepatitis B serum, achieving higher classification accuracy compared to traditional machine learning methods.

As forensic analysis continues to advance, such as in the understanding of source identification and analysis of trace quantities of bodily fluids, spectroscopic techniques and machine learning are playing a significant role. Igor K. Lednev, a chemistry professor at the University at Albany, SUNY, in Albany, New York, has been working in this field with his team. The analytical methods currently under investigation include Raman spectroscopy, attenuated total reflection Fourier transform infrared (ATR FT-IR) spectroscopy, and advanced chemometric classification and analysis methods. We recently interviewed him about his work.

We explain how to characterize barium fluorohalides with Raman spectroscopy.

Innovative database search technology can help Raman spectroscopists identify molecular vibrations; here, we show how to use these tools more effectively.

In this study, the nitrophenol isomers, in solid and liquid phases, were analyzed using Raman spectroscopy, laying the groundwork for determining nitrophenol isomers in environmental monitoring with this technique.

Katsumasa Fujita, a professor of applied physics at Osaka University, has been working to improve techniques for imaging biological samples using spontaneous Raman scattering.

Zac Schultz of The Ohio State University and his team used tip-enhanced Raman spectroscopy (TERS) and surface-enhanced Raman spectroscopy (SERS) with gold nanostars to investigate chemical reactions involved in protein–ligand binding. He recently spoke with Spectroscopy about his findings.

Bhavya Sharma is the winner of the 2021 Emerging Leader in Molecular Spectroscopy Award. We recently interviewed her about her work conducting research to detect active and important biomolecules related to hormone regulation, neurological health, and disease diagnosis.

Roy Goodacre, a professor of biological chemistry at the University of Liverpool in the United Kingdom, first used SERS to achieve whole-organism fingerprinting of bacteria and then explored SERS in a variety of other applications, including within biotechnology, disease diagnostics, quantitative detection, imaging, food security, and more. Goodacre is the 2021 winner of the Charles Mann Award for Applied Raman Spectroscopy. This interview is part of an ongoing series of interviews with the winners of awards that are presented at the annual SciX conference.

Analytical chemists are continually striving to advance techniques to make it possible to observe and measure matter and processes at smaller and smaller scales. Professor Vartkess Ara Apkarian and his team at the University of California, Irvine have made a significant breakthrough in this quest: They have recorded the Raman spectrum of a single azobenzene thiol molecule. The approach, which breaks common tenets about surface-enhanced Raman scattering/spectroscopy (SERS) and tip-enhanced Raman spectroscopy (TERS), involved imaging an isolated azobenzene thiol molecule on an atomically flat gold surface, then picking it up and recording its Raman spectrum using an electrochemically etched silver tip, in an ultrahigh vacuum cryogenic scanning tunneling microscope. For the resulting paper detailing the effort [1], Apkarian and his associates are the 2021 recipients of the William F. Meggers Award, given annually by the Society for Applied Spectroscopy to the authors of the outstanding paper appearing in the journal Applied Spectroscopy. We spoke to Apkarian about this research, and what being awarded this honor means to him and his team. This interview is part of an ongoing series with the winners of awards that are presented at the annual SciX conference. The award will be presented to Apkarian at this fall’s event, which will be held in person in Providence, Rhode Island, September 28–October 1.

This article discusses how FT-IR and SERS is being used to detect counterfeit pharmaceutical drugs.

This article discusses coherent Raman imaging and how it can visualize and quantify cutaneous pharmacokinetics (PK).

Working at the frontiers of biotechnology, fiberoptics, lasers technique, and molecular spectroscopy, Tuan Vo-Dinh of Duke University has developed multiple sensor technologies for medical research and diagnostics. Throughout this work, Vo-Dinh and his research colleagues have brought spectroscopy to biomedical applications. In this second recent interview, Vo-Dinh talks about his research work and philosophy.

An increasing number of antibiotic residue problems in food have emerged around the world. We examine how SERS is used to identify antibiotic residues in chicken, focusing on doxycycline hydrochloride and tylosin.

This year’s molecular spectroscopy award recipient is Bhavya Sharma, who is demonstrating research leadership focused on neurochemical detection using SERS and SORS Raman spectroscopy.

To better understand Raman spectral profiles, we briefly examine spectral line shapes, while discussing spectral shape, bandwidth, and broadening as percentage of Gaussian and Lorentzian components.

This article explains the key steps of using Raman technology to investigate carbon and carbon-based materials—such as carbon nanotubes, graphene, and carbon fibers and composites—as well as the process of analyzing the spectra.

In SERS experiments, the excitation laser power needs to be kept at a level that enables detection but avoids damaging the sample, as these examples illustrate.

Igor K. Lednev at the University at Albany SUNY in New York explains advances in forensic analysis using a variety of chemometrics techniques to classify ATR FT-IR and Raman spectra of bodily fluids.

Inline FT-NIR and offline terahertz Raman imaging analysis are used to characterize active pharmaceutical ingredient (API) crystallinity and to monitor different solid physical states of the API, to control process parameters of hot melt extrusion.

Using confocal Raman imaging and other advanced measurement techniques, we study the localized strain characteristics of tungsten diselenide (WSe2), an important nanomaterial used for optoelectronic device applications.

Using Raman imaging, wild-type and engineered yeast cells were compared for their ability to produce bioactive compounds. Raman imaging microscopy is able to visualize locales, relative abundance, and production efficiencies of biologically active compounds for the individual yeast cells.

SERS can amplify Raman signals, but to make the technique practical for industrial use, large quantities of substrate are needed. The approach described here could enable cost-effective, reproducible manufacturing of SERS substrates at large scale.

Perovskites are known to be useful for fabrication of solar cells, and their crystalline structure plays an important role in their electronic properties. Here, we show how Raman analysis is able to confirm the presence of the required crystalline phase for solar cell production.

We illustrate how matching the optical properties of the microscope objective with the sample properties improves the spatial resolution and chemical speciation in depth profile measurements using confocal Raman microscopy.

Raman spectroscopy offers promise for the evaluation of breast cell lines and tissue. Rina Tannenbaum of Stony Brook University discusses this work.