Recent Advances in Infrared Spectroscopy

In honor of Spectroscopy’s celebration of 30 years covering the latest developments in materials analysis, we asked experts to assess the current state of the art of six key spectroscopic techniques. Here, the experts weigh in on what they considered the most important recent advances in infrared (IR) spectroscopy.

According to Rohit Bhargava, who is a professor and the Bliss Faculty Scholar at the University of Illinois at Urbana-Champaign, the single most important development has been the opening up of the design space in IR instrumentation. A decade ago, there was very little differentiation among commercial offerings. Now that has changed. “New sources and improved computing, detectors, and advances in theoretical understanding have led to new designs and expanded choices,” he said.

Timothy McIntyre, the manager of the analytical chemistry team in the Innovation and Commercial Development division at Tate & Lyle, agreed with Bhargava about the importance of computing. “An area that adds tremendous speed and efficiency to the implementation of IR spectroscopy has been software that easily integrates functions such as sample presentation and control, quantitative analysis, classification, and identification through database searching and data handling and communication,” he said.

Peter Griffiths, who is an emeritus professor of chemistry at the University of Idaho and the principal of Griffiths Consulting LLC, identified two developments as being the most important recent instrumental advances: nanospectrometers and quantum cascade lasers. “If I had to choose between them, I’d probably opt for nanospectroscopy,” he added.

Daniel Schroeder, a senior research specialist at 3M, also identified multiple areas of recent advancements, including sampling accessories, mobile instruments, and hyphenated instruments. “Attenuated total reflection (ATR) crystals have been used for many years, but they have been incorporated in a variety of sampling devices more recently, making FT-IR ATR ubiquitous in both laboratory and process environments,” he remarked.

“An exciting advance in IR spectroscopy has been the development of coherent 2D IR spectroscopy,” said Martin Zanni, who is the Meloche-Bascom Professor of Chemistry at the University of Wisconsin-Madison. “Analogous to the invention of 2D nuclear magnetic resonance (NMR) spectroscopy in the 1970s, it is now possible to create IR pulse sequences to measure 2D IR spectra with diagonal peaks and cross peaks,” he explained. “Like 2D transformed NMR, 2D IR is now transforming mid-IR spectroscopy.”

Portable Instruments

Given the increasing prevalence of portable or handheld instrumentation in many areas, we also asked our panel to comment on this trend with respect to IR spectroscopy.

“Most handheld instruments don’t operate at a resolution that is much better than 4 cm^-1,” said Griffiths. “If higher resolution is needed, someone will develop an appropriate spectrometer.”

Schroeder envisions a new mobile IR instrument in which the sensor collects spectral data and the device then transmits the data to a remote spectral processing system for more mathematically intense computations. The advantages of such a system would be reduced cost and streamlined implementation and maintenance by requiring that methods be loaded only once, onto the single centralized processing system.

Such a setup could also overcome a shortcoming of many portable instruments-their lack of quantitative analysis software, which limits their use to simple ID verification applications. In Schroeder’s scenario, the more expensive electronics and software required for data analysis-such as chemometric analysis, neural network, process control, statistical analysis, and so forth-could reside in the centralized data processing system. “The portable IR instruments would only need to collect the spectra, and pass those spectra to the centralized processing unit for analysis,” he explained. 

Bhargava had a positive forecast for portable IR in industrial settings. “Process deployment of IR spectroscopy will be an important growth market with industry relying on spectrometers to be at the core of integrated sensors,” he predicted.

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This article is an edited excerpt of “Analysis of the State of the Art: IR Spectroscopy.” 

The article is part of a special group of six articles covering the state of the art of key techniques, also including near-infrared (NIR) spectroscopy, Raman spectroscopy, inductively coupled plasma–mass spectrometry (ICP-MS), laser-induced breakdown spectroscopy (LIBS), and X-ray fluorescence (XRF) spectroscopy.