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Polyurethanes are widely used, from medical devices to electrical materials to consumer goods. These materials have chemical stability issues which impact the mechanical stability. Infrared micro spectroscopy has been used to study polyurethane degradation, but due to experimental limitations, samples examined were no smaller than approximately 15 microns on a side. Because of the complex chemistry of urethanes, chemical examination of the material on a much higher spatial resolution scale would be valuable.A relatively new technique, Attenuated Total Reflection Fourier Transform Infrared Spectrochemical MicroImaging has been used to examine degraded polyester urethanes. Rather than using a single-element detector, a two dimensional array detector generates thousands of spectra simultaneously. In addition, a germanium prism generates a magnification effect; resulting in a significantly higher spatial resolution. The net output of the analysis is a hypercube of high resolution infrared spectra showing urethane degradation progression on a much smaller spatial scale than was previously possible.

Infrared spectrometry is demonstrated to be a powerful tool for solving problems related to the use of polymeric materials in food packaging. These problems range from the identification of minute amounts of materials, such as flavor agents retained in coatings, to the investigation of adhesion problems in laminate wraps and to the identification of gross amounts of deposit discovered in a lemonade can. In some instances, a complex mixture of organic vapors is separated using standard chromatographie techniques, with subsequent analysis by FT-IR spectroscopy. In particular, the utility of headspace GC/ FT-IR analysis is discussed, as this technique is not routinely used. In other cases, the solid samples themselves are examined by more conventional FT-IR methodologies.

The availability of commercial step-scan FT-IR instrumentation has led to the rapid development of a number of new and rediscovered applications. These take advantage of the peculiar features of step-scan FT-IR, for instance, separation of spectral and temporal multiplexing. This paper describes experimental arrangements for several studies including modulation spectroscopy, time resolved spectroscopy (TRS), vibrational circular dichroism, and photoacoustic spectroscopy. The use of devices external to the spectrometer (e.g., lock-in amplifiers) is described, with attention to multiple channel data collection.

The advantages of Thermal Gravimetric Analysis/Fourier Transform Infrared Spectroscopy (TGA/FT-IR) for material characterization has been successfully demonstrated by the analytical chemist. This hyphenated technique has generally been utilized for assigning evolved gases to the detected weight losses of the material as it is being heated. In this study, the FT-IR is used to monitor the reaction products which evolve from pyrite as it is slowly heated from room temperature to 600 degree(s)C under air. The spontaneous and cyclic releases of sulfur dioxide are monitored during the experiments by high resolution Evolved Gas Analysis.

FT-IR time resolved spectroscopy (FT-IR TRS) with simultaneous temporal and spectral resolution has emerged as a powerful technique to elucidate dynamic, segmental information concerning both orientation and conformational changes of liquid crystalline molecules during the electric-field-induced reorientational transition. This paper describes the experimental setup for time-resolved measurements using a step-scan FT-IR spectrometer and reports the results of dynamic analysis of ferroelectric liquid crystals (FLC).

Capillary gas chromatography/mass spectrometry (GC/MS) has routinely been used by the analytical chemist to separate and identify low levels of environmentally important compounds. A GC/Cryogenic Trapping Fourier Transform Infrared Spectrometer (Tracer) provides the sensitivity of the GC/MS with the added capability of differentiating between compounds of the same mass. In this work, the Tracer was utilized to study low levels of six Polychlorinated Biphenyls (PCBs), eight Chlorinated Dibenzo-p-Doxins and Norflurazon. In all cases, picogram levels of these compounds were easily detected from `on the fly' generated IR chromatograms. Since the separated compounds eluting from the capillary column are cryogenically trapped onto a moving liquid nitrogen cooled ZnSe crystal, excellent signal-to- noise spectra of these same compounds may be collected after the run by returning to the same areas of deposition and signal averaging.

Liquid crystal systems which undergo reorientation under the influence of an applied electric field are of great interest in terms of both applied systems, such as liquid crystal displays, and in model systems. Analysis of the molecular dynamics of these systems can be performed by step-scanning, time resolved spectroscopy (TRS). Typically, these liquid crystal systems are studied in simple transmission cells, which mimics the application in display units and gives information on the bulk reorientation of the system. However, using a modified ATR cell, information on the reorientation at the electrode surface can be studied. Here, we present the results of our studies on two liquid crystal systems, with details on the construction of transmission and ATR cells used for liquid crystal studies.

Thermal analysis of complex samples has been greatly assisted by the coupling of FT-IR analysis to the TA experiment, and evolved gas analysis by infrared spectroscopy has been very successful in combined TGA/FT-IR experiments. During a combined DSC/FT-IR experiment the FT-IR analysis is performed on the sample itself, by using an infrared transmitting microscope. A curing reaction and thermal changes in a polymer are used to demonstrate the use of a combined DSC/FT-IR system. By combining a simultaneous TGA/DSC instrument with FT-IR evolved gas analysis, we are now able to obtain three sets of complementary information, on the same sample, in one experiment. A study of the thermal behavior of zinc stearate is reported by using TGA/DSC/FT-IR.

The infrared microsampling technique has been successfully applied to a variety of biological systems. A microtomed tissue section may be prepared to permit both visual and infrared discrimination. Infrared structural information may be obtained for a single cell, and computer-enhanced images of tissue specimens may be calculated from spectral map data sets. An analysis of a tissue section anomaly may gg suest eitherprotein compositional differences or a localized concentration of foreign matterp. Opaque biological materials such as teeth, gallstones, and kidney stones may be analyzed by microreflectance spectroscop. Absorption anomalies due to specular dispersion are corrected with the Kraymers-Kronig transformation. Corrected microreflectance spectra may contribute to compositional analysis and correlate diseased-related spectral differences to visual specimen anomalies.

Due to the strong absorbance of water in the mid-infrared region of the spectrum, studies of aqueous solutions have usually been performed by either spectral subtraction of the pure solvent from the spectrum, or by substituting heavy water in the system to study absorbances below the 1640 cm-1 scissor. Both methods can lead to erroneous results, if invalid assumptions are made in each case.

Infrared emission spectroscopy has been used routinely to study samples at high temperatures, such as rocket plumes. The designs of modern FT-IR instruments and a new emission accessory having high optical throughput, now allow the observation of emission spectra at much lower temperatures than previously. This greatly enhanced sensitivity to emission energy can be used routinely to either record spectra at room temperature, or obtain information about very thin films.