Infrared (IR) Spectroscopy

A2 Technologies' Exoscan hand-held FTIR (Figure 1) is increasingly being used by researchers involved in the geosciences for analysis of rocks, minerals, and soil for a broad variety of applications.

Fourier transform–infrared (FT-IR) spectroscopy is convenient and effective for the analysis of foreign matter and other defect analysis. It is widely used to confirm, identify, and detect matter in many applications, including raw materials, medical products, packaging, and coatings.

Infrared (IR) spectroscopy is one of the most versatile and powerful analytical tools that we have today for the characterization and identification of materials. Its strength lies in its ability to handle a broad range of material types, in any physical state, at a wide range of concentrations, and on many occasions, with direct methods of measurement. These strengths are about to be enhanced by the use of instrumentation that utilizes a choice of broadly tunable laser devices, covering the sweet spot of the mid-IR spectrum, the "fingerprint region." These systems currently cover the spectral range of 6–12 ?m (1665–830 cm-1), which provides spectroscopic access to almost all classes of chemical compounds. This article reviews the benefits offered by such a laser system for a wide range of new and challenging applications.

Relying primarily on transmission or reflection techniques, FT-IR microscope and imaging systems often can require tedious sample preparation to obtain representative data from a sample. Conversely, similar to a sample compartment attenuated total reflectance (ATR) accessory, the ATR microscope objective requires no sample preparation as the sample can simply be contacted with the ATR element, or crystal, and then the sample spectra can be collected using the microscope detector. The ATR objectives discussed here are designed to offer simultaneous video observation of the selected sample area during infrared data collection. These ATR objectives provide a unique capability for sample observation and infrared data collection when utilizing a software mapping feature offered with the FT-IR microscopes discussed.

The most popular design of a hollow waveguide consists of silica glass tubing coated internally with silver and silver iodide to create a highly reflective surface. The external surface of the silica glass tubing is coated with an acrylate to enhance waveguide strength. In contrast to traditional mid-IR optical fibers, such as chalcogenide glass, and silver halide polycrystalline fibers, hollow waveguides offer distinct advantages for mid-IR remote sampling. Hollow waveguides, which were recently incorporated into a mid-IR sampling accessory, provide enhanced durability and span the full mid-IR range. This article details the technology and performance of hollow waveguides in the mid-IR spectral region and presents applications in remote sampling.

Establishing credibility and reliability of the information provided by a Fourier transform–infrared (FT-IR) spectrometer is paramount to mitigating risk in the QA/QC laboratory, where simple, fast and error-free analysis of unknown materials or material verification are required. To meet the demands of a modern QA/QC laboratory, FT-IR spectrometers must include capabilities that shift the burden of proving the reliability of the information away from the analyst so they can concentrate on the sample, not on verifying the integrity of the data. Recent design advances in both FT-IR spectrometer hardware and software give users greater confidence by continually reporting instrument status and performance verification, efficiently and effectively running pass–fail tests against specification, and easily adjusting to the degree of variation in a given set of products.

Characterization of trace evidence is an invaluable asset to the forensic scientist in solving crimes. In particular, the characterization needs to be specific enough so that the identification of material collected at a crime scene can be identified forcefully with material collected from a suspect's environment. Colored microscopic fibers can be discovered easily at a crime scene and collected for analysis. The question is what physical tool can be used to characterize these fibers. Fourier transform–infrared (FT-IR) spectroscopy is a well-established method for characterizing trace evidence. In this article, FT-IR, FT-Raman, and dispersive Raman spectra of a series of prepared fibers will be evaluated for their information content.

Advances in hardware and in data analysis make Raman and laser-assisted spectroscopy techniques valuable in hazardous materials analysis.

According to the Scientific Working Group for the Analysis of Seized Drugs (SWGDRUG), techniques with the highest discriminating power should preferentially be used for forensic identification of seized drugs.

Grazing angle Ge ATR spectroscopy is extremely sensitive to monolayers and thin films on high refractive index substrates such as Si.

Fourier Transform-Infrared Spectroscopy (FT-IR) is a powerful technique for fast and non-destructive analysis of plastic films.

Fat and other nutritional values can easily be determined by NIR analysis. However a proper sample preparation beforehand is essential for a correct result.

Infrared spectroscopy is a powerful analysis technique used in the semiconductor industry to ensure the quality of silicon and silicon wafers. The authors discuss the use of an inexpensive, lab-based system to measure carbon and oxygen concentrations in silicon to the level of precision required by the solar silicon industry.

The authors illustrate the value of FT-IR–ATR with sample viewing through the analysis of an ink source on paper.

The authors discuss the use of vibrational spectroscopy to differentiate an authentic article from a counterfeit one throughout a product's lifecycle, from component receipt at the site of manufacture, to product receipt by the end user.

The authors discuss the combined use of Raman and FT-IR spectroscopy in fields such as forensic science, biomedical science, catalysis, and polymers.

Transmission methods are often affected by film thickness and can result in inaccuracies. Polarization measurement using attenuated total reflectance (ATR), a Fourier transform–infrared (FT-IR) technique, is offered as an alternate resource because it is not adversely affected by film thickness.

The authors look at the ways in which an imaging FT-IR microscope system with an integrated linear array detector can aid in the examination of a wide array of samples.

Spectroscopy presents a comprehensive index of our FT-IR articles since 2004.

Data from the U.S. Air Force Defense Support Program (DSP) missile warning satellites collected early June 1 over the central Atlantic Ocean is being studied to see if it detected the impact or a fiery breakup of the Air France Airbus A330 that disappeared enroute to Paris, France, from Rio de Janeiro, Brazil early on June 1.

Infrared (IR) spectroscopy and Raman spectroscopy are very complementary methods. The strongest demand tends to come from applications that require analytical information from a potentially broad range of compounds and functional groups. The global market for combined Raman and FT-IR accounts for a small but growing percentage of both the broader IR and Raman spectroscopy markets.

This article discusses instruments that can be used in the field to rapidly and accurately identify various explosives and their precursors.

Fourier-transform infrared (FT-IR) and horizontal attenuated total reflectance (HATR) techniques are used to obtain the FT-IR spectra of the yellow foxtail seed, the giant foxtail seed, and the green foxtail seed.

The authors discuss the use of near-infrared spectroscopy to determine the age of a bloodstain, which can be critical in helping establish when a crime was committed.

Gas sensing in the mid-infrared region is examined.