The application of infrared spectroscopy to the study of proteins and protein systems has a relatively long history when compared to other biomedical infrared applications. However, the application of infrared to studies of proteins in aqueous solutions has a much more limited history, with work beginning in the mid-1960's. Aqueous work conducted in the 1960's used conventional dispersive infrared spectrometers with limited frequency accuracy and signal-to-noise ratios, which made it very difficult to observe the weaker amide and skeletal vibrations present in the proteins and polypeptides under study. Thus, it was the common consensus of workers at that time (1) that infrared protein spectra were for all intents and purposes very similar to one another, which is in fact the case; and (2) that when working in aqueous solutions, proteins such as those found in blood would be indistinguishable due to this great similarity, which has not proven to be the case.

Spectroscopic studies of electrode processes at molecular level are necessary both for a more detailed understanding of the fundamental electrochemical reactions involved and for the development of better electrode materials. Such investigations require molecular-specific, non destructive surface analytical techniques capable of analyzing solid-liquid interfaces in situ, without changing the structure of the often unstable reaction products during the measurements. It has been demonstrated previously that IR-spectroscopy fulfills these requirements. Recently, the development of FTIR-spectrometry provides the sensitivity and speed necessary to study also shortliving intermediates generated in a spectroelectrochemical cell during potentiodynamic measurements. This paper deals with the advantages and limi-tations of the different IR-spectroscopic reflection techniques developed and applied since 1980 for the in situ study of metal and organic polymer electrodes in contact with aaueous and non aqueous electrolytes (external reflection techniques, internal reflection technique) . Special emphasis is placed on recent combined electrochemical and FTIR-ATR-spectroscopic investigations on polythiophene, poly-3-methylthiophene and polybithiophene.

The latest advancement and potentiality of FT-IR as a tool for industrial materials characterization are reviewed. The position and advantages of FT-IR among other analytical techniques are also discussed, especially in surface and microanalyses. Several examples of FT-IR applications being done in TRC are presented. A study on bilayer membranes with embedded polypeptides, dispersed in water is shown as an example of bulk analysis. Surface analysis of an oxide layer on a silicon wafer by ATR using the wafer itself as an IRE plate is explained. Potentiality of PAS for a deep sampling probe on multilayered composition is illustrated. Finally the present stage of FT-IR microanalysis using an infrared microscope is discussed using examples on real samples.

We have made quantitative infrared intensity measurements by FT-IR transmission and attenuated total reflection spectroscopy of liquids and by specular reflection spectroscopy of single crystals. Knowledge of the accuracy of the measurements is necessary, and this paper emphasizes how this was determined for liquid samples. It is concluded that a value of an absorption coefficient that is determined from 4 to 6 transmission spectra of a pure liquid is likely to vary by ±0.6% to 1.5%, depending on the cell used, the beamsplitter used and the optical alignment of the interferometer and detector, provided that the cell is mounted firmly. The average value is likely to agree with the available calibrated value to within 3%, which is within the approximately 5% accuracy of the calibrated value. We believe the main source of error to be the effect of the infrared cell on the light path through the instrument. An attenuated total reflection method has been developed for the easy evaluation of the absorption and dispersion parameters of liquids to an accuracy of about 6% for bands of medium intensity. This accuracy is compatible with typical literature data and is useful to current theory. Specular reflection measurements were calibrated against a silicon standard. They are reproducible to about 3% of the reflectance value, largely due to the surface and position of the sample.

The basic premise of Fourier domain processing is that the Fourier transform does not alter the information content of a spectrum. Spectra have traditionally been recorded in the frequency, wavelength or wavenumber domain, and this is referred to as the spectral domain. The Fourier transform of a spectrum converts the data to the time, wavenumber or retardation domain, known as the Fourier domain. Data manipilation is often carried out in the Fourier domain, particularly Fourier self-deconvolution, smoothing, and differentiation. These operations involve convolution in the spectral domain, which is equivalent to a multiplication in the Fourier domain. It is mathematically less expensive to achieve these operations in the Fourier domain. Other data handling operations can be achieved in the Fourier domain. The first of these is the Gram-Schmidt orthogonalization of raw GC/FT-IR spectrometry interferograms to construct infrared-based chromatograms. Search systems and structure elucidation methods can also be effectively carried out using Fourier transforms of absorption spectra.

As a spectroscopist, one rapidly learns that obtaining a spectrum of a sample is only part of the work. Many times the real challenge comes in interpreting the spectrum. In correlation transform spectroscopy, commonly referred to as near-infrared analysis, a large emphasis is placed on the data interpretation phase. To make the spectral results intelligible to the analyst, near-infrared analysis correlates a series of spectra with the known analyte concentration. This correlation transforms the spectra so that the relationship between the analyte and the spectra is displayed. This process can be extended to deduce the spectrum of a pure component from those of mixtures, or to deduce the analyte concentration in an unknown sample. Interestingly, near-infrared analysis has shown that surprisingly little spectral resolution is required to quantitate many analytes. Thus, instrumentation designs are being developed which make use of very broad filters made of polymers or other materials. These instruments provide spectral information in much the same way that the eye does.

It is not inappropriate that John Overend should be remembered at the 1985 Conference on FTIR. His premature loss in November, 198k at age 56, at the height of his powers, is so recent; although no paper of his appears on the program, the influence of his work shows up in a number of ways, not only in the explicit references; the participants include many of his former students and colleagues; and so many recall him as a spectroscopist and as a man and a friend worth knowing.

Polarization modulation can be used to obtain infrared (IR) spectra of any sample which absorbs light of two orthogonal polarizations to different extents. Examples of applications include vibrational circular dichroism (VCD), infrared reflection-absorption spectroscopy (IRRAS), infrared linear dichroism of statically-oriented samples, and time-dependent dynamic infrared linear dichroism (DIRLD) of samples under small-amplitude oscillatory strain. Modulation spectroscopy can be performed on either Fourier transform or dispersive IR spectrometers. A photoelastic modulator (PEM) placed in a linearly-polarized beam of light can alternate the state of polarization at frequencies on the order of 50 kHz. This enables a small difference signal to be obtained in a single measurement without having to subtract or ratio two separately-measured large signals. The principles of polarization modulation are developed and examples of VCD, IRRAS, and DIRLD presented.

Infrared Spectral Searching has progressed rapidly over the past two years since the last FT-IR Conference in Durham, England. In addition, if we compare the searching capabilities available to the Infrared Spectroscopist today with those that were available a short four years ago at the last North American Conference held in Columbia, South Carolina, then the advancements are even more impressive. In retrospect, I would describe the state-of-the-art in Spectral Searching at the 1981 FT-IR Conference as "Level 1 Searching", where the spectroscopist was limited to measuring a spectrum for his unknown material, and automatically searching it against very limited libraries at that time to obtain a search report. The report generally provided an ordered ranking of the best matches, chemical name, and a spectrum number so the reference spectrum could be located and reviewed in books. In 1981, there existed a total of three commercially available infrared search packages at the instrument level. Two of the packages were available for FT-IR instruments and the third was available on a dispersive instrument. Only the FT-IR packages allowed viewing the reference spectra on the CRT along with the unknown spectrum by automated spectral retrieval from the reference libraries stored on disk. However, the primary source of reference spectra was still predominantly hard copy.

Two kinds of studies are mainly considered from conventional emission and laser-induced fluorescence experiments. Several new results are presented : observation of new electronic states, assignment of weak, quasibound and perturbed transitions, studies at the dissociation limit and of collision processes.

A high-resolution FTIR spectrometer had its first flight in May of this year as part of the Spacelab-3 science pay-load. The experiment - Atmospheric Trace Molecule Spectroscopy (ATMOS) - is designed to obtain fundamental information related to the physical and chemical structure of the Earth's upper atmosphere (from 15 to 150 km altitude). There are two major aspects to the investi-gation: the first is the determination of the detailed composition of the stratosphere and mesosphere, and its global, seasonal and long-term variability; the second is the study of the partitioning of solar energy at levels in the atmosphere characterized by dissociation of the constituents and by the breakdown of thermodynamic equilibrium.

Spectroscopy can be described as an inversion technique for the retrieval from measured data of an unknown spectral distribution. The implications which follow from this general approach are discussed. It turns out that spectroscopy belongs to the category of ill-posed problems that have more degrees of freedom than data. A revised concept of resolution is suggested, and the role of the model for the data interpretation is underlined.

The last decade has been a period of astonishing growth and vigor for FT-IR spectroscopy. The first International Conference on Fourier Transform Spectroscopy held in Aspen, Colorado, in 1970, described new instrumentation using Michelson interferometers that had been developed in response to problems in astro-physics, where faster acquisition of data and better ways of handling the large quantity of data generated were needed. The problems had driven the development of new instrumentation. With this impetus, instrument manufacturers introduced reliable, computerized FT-IR instruments for use by industry. These new instru-ments, with their speed and advanced data processing capabilities, led to an explosion of new examples of practical problem solving, as well as new sophistication in analyzing structures of materials or composition mixtures. Today the field of industrial infrared spectroscopy which was literally "transformed" just 15 years ago is vigorous, healthy, and still expanding. Perhaps we have now come full circle, for today industry is again articulating ever more challenging problems that need solving via novel instrumentation and/or accessories. This will lead to a tomorrow in areas that have been elegantly described in the invited lectures and poster contributions of this conference. In this paper, we will describe some typical uses of FT-IR today and from them predict where FT-IR will "walk tomorrow". We will concentrate on industrial applications because that is the community we represent. It is also relevant to point out that the growth and success of new analytical tools or techniques are dependent on the extent of use by industry. Industrial practical problem solving - and just because it's practical or solving a problem does not preclude good science and basic work - drives the development of newer and better ways to get answers to problems or to understand properties of materials.

Fourier Transform Infrared (FTIR) was used to investigate the thermal stability of bisphenol AF crosslinked vinylidene (VF2)/hexafluoropropylene (HFP) copolymers. The uncrosslinked copolymers have the same copolymer ratio of VF2/HFP (3.5/1) with different molecular weights and dynamic shear moduli. The FTIR spectra of the crosslinked copolymer network show that the thermal stability is related to the molecular weights and dynamic shear moduli of the linear, uncrosslinked copolymers, and the concentrations of base and metal oxide filler in the precrosslinked copolymer films. The thermo-oxidation of the crosslinked copolymers by X-ray Photoelectron Spectroscopy (XPS) also shows dependence on the molecular weights and dynamic shear moduli.

Diffuse reflectance Fourier transform infrared spectroscopy has been used to obtain IR spectra of epoxy-graphite prepregs and cured panels. The spectra are influenced by fibre orientation and front-surface reflection effects which limit the usefulness of the method for quantitative analysis. However, for qualitative work, excellent spectra can be obtained with practically no sample preparation.

A spectroelectrochemical technique based on the reflection absorption spectroscopic method is described whereby high resolution in situ vibrational spectra of electrogenerated reaction intermediates(including radicals) and species adsorbed on electrode surfaces can be obtained. Theoretical and experimental aspects of the method,in a single reflection mode, are discussed. The application of this technique to aqueous and non-aqueous systems, using platinum and carbon electrodes are described.

Pyrolysis GC-FTIR has been used to study the effects of burning rate promoters on decomposition products of nitramine propellants. The nitramine materials studied are cyclotrimethylenetrinitramine (RDX) and cyclotetramethylenetetranitramine (HMX), and the burning rate promoters consist of an organic and in inorganic salt of the BloH10-2 anion. The samples have been pyrolyzed under controlled conditions of heating rate and duration, and were separated using both packed column (with thermal conductivity detection) and capillary column (with flame ionization detection) chromatography. Both the packed and capillary columns yielded peaks which were not identifiable on the basis of retention times; consequently, FTIR was used to elucidate the structure of these components. In some cases, components not separated chromatographically were individually determined by their FTIR spectra. Also, peaks from various runs having similar retention times were found to have different chemical structures from their spectra. DSC results for RDX and RDX mixtures are also shown.

Variable angle ATR was used to obtain a depth profile analysis of the films cast from blends of a high molecular weight styrene-acrylate copolymer colloid, an alkali soluble styrene-acrylic resin and an emulsified polypropylene. The dried films show a homogeneous distribution of the styrene-acrylate colloid particles and the solution polymer, however, the particles of polypropylene have a concentration gradient through the film thickness.

The application of FT-IR spectroscopy to study low-temperature phase transitions in crystalline solids is illustrated by our investigations of (NH4)2NaFeF6 and Cd(C104)2.6H20 between 10 and 300 K. The possibilities of this technique and its limitations are discussed.

Fourier Transform atomic emission spectroscopy is well suited to the determination of nonmetals in the red to near infrared region from 7,900 to 15,800 cm-1 (1) . The speed of Fourier Transform spectroscopy allows full spectrum monitoring of transient atomic emissions on a time scale as short as 0.5 s. The present report demonstrates new applications of this system for "on the fly" collection of nonmetal atomic emission spectra produced as gas chromatographic effluent is introduced into an atmospheric pressure helium microwave induced plasma (MIP). Simultaneous multi-element determination of C, H, N, 0, S, Si, P, F, Cl, Br, and I is now possible with the red to NIR Fourier transform atomic emission spectrometer.

Isotopic uncoupling vibrational spectroscopy is being used to study inter-species hydrogen bonding in aqueous hydroxylammonium nitrate (HAN) as a function of concentration (9.5-17 Molar) and temperature (-170 to 70°C).

A Fourier spectrometer was used in order to measure the spectral emissivity E(k) of human skin in the FIR region k=190-420 cm-1. Three studies on patient groups with defined chronic diseases have been performed: patients with untreated bronchial carcinoma, patients with rheumatic arthritis and patients with chronic renal insufficiency. In comparison with a symptomfree control group all patient groups show significant differences in E(k). As result of a discriminant analysis a separation of 95.7% between carcinoma patients and control persons is possible. The separation quotes between the other groups indicate that patients with malignant neoplasms can be discriminated from other chronically ill persons.

High resolution graphical analysis techniques of FTIR spectra permit correlations between spectral features to be easily visualized. The techniques are illustrated with an analysis of FTIR difference spectra showing the kinetics of coal drying.

Reflection spectra containing phase as well as intensity information were collected on a FT-IR spectrometer using two linear polarizers. The sample consisted of a poly(vinyl acetate) (PVAc) film on a copper substrate. Using well known principles of ellipsometry, the relative phase retardation (delta) and relative amplitude (psi) were calculated from these measurements.

FTIR-difference spectra can be obtained from both photoreceptor membrane, involved in visual detection, and purple membrane, involved in light-driven proton pumping. Peaks often can be assigned to single molecular groups, thereby providing information about the molecular mechanisms of these processes. Fourier self-deconvolution can be used to separate overlapping bands.

Water absorbed in polyethylene terephthalate (PET) and sulfonated polyethylene terephtha-late copolymer (S-PET) were studied by FTIR spectroscopy. The FTIR spectra of PET and S-PET for different amounts of absorbed water were measured. The subtraction spectra of water containing PET have been determined using nitrogen dried PET as the reference. The characteristic bands arising from water-polymer interactions were obtained. The subtraction spectra show that four oxygen associated infrared bands 1720, 1260, 1122 and 1101 cm-1 were splitted into ten bands. The subtraction spectra of S-PET resemble those of PET. From observed results, a model of hydration in PET and its copolymer is suggested.

Diffuse reflectance infrared Fourier transform (DRIFT) and matrix isolation gas chromatography Fourier transform infrared (MI/GC/FT-IR) spectra of the 22 tetrachloro dibenzodioxin (TCDD) isomers have been measured. The spectrum of each TCDD isomer is unique.

The advantages of FTIR/PAS are outlined for the analysis of textiles, and the application of the technique is illustrated by spectra obtained from an extended range of natural and synthetic materials. The sampling advantages and data handling facilities of FTIR/PAS permit the study of textile additives and forensic type samples.

Fourier Transform Infrared Photoacoustic Spectroscopy (FTIR-PAS) is used to study the contamination of alkyd painted panels by liquids and solids. These alkyd painted panels are stainless steel panels coated with primer and an alkyd resin based paint which the Army uses for its vehicles. Portions of these panels were contaminated by dimethyl methyl phosphonate, tri-(2-ethylhexyl) phosphate, and triphenyl phosphate. The panels were then studied using FTIR-PAS, and the spectra identified.

Hormonal steroids such as 17α-estradiol derivatives, labelled with organometallic moieties, have been tested as markers for hormone receptor assay. Among the organometallic labels used were: Cr(C0)3 and Cr(C0)2(CS), which can be attached to the A ring of the steroid, and Co2(C0)6 and Mo2(7-15-05H5)(C0)4, which can be bonded to acetylenic groups in the 1713-position of the five-membered ring of the steroid. The new analytical approach is based on the FT-IR detection of the υ(CO) modes of the organometallic markers. The present estradiol-receptor detection level for 10,000-20,000 scans at 4 cm-1 resolution is about 100 fM, i.e., in the neighbourhood of physiological levels.

Current spectroscopic investigations of thermally induced changes in the lipophilic pathway of the stratum corneum are beginning to provide insight into the molecular structure and barrier function of the stratum corneum. Enhanced permeability of lipophilic compounds has been noted between 37 and 70°C. Reversible solid to liquid transitions occur in the lipophilic pathway of the stratum corneum in the temperature region associated with enhanced permeability.

The study of gas-solid interactions is of much importance for the understanding of the mechanisms of catalytic reactions. Such systems have traditionally been studied by flowing a gas of interest through a heatable, evacuable chamber containing a thin, free-standing pressed pellet of a solid (1). The preparation of so thin a pellet can be rather time-consuming. FT-IR Diffuse Reflectance (DR) is a popular technique for the study of solids (2-4). Little, if any, sample preparation is required and powdered catalysts may directly be analyzed. The evacuable, heatable chamber allows a sample to be studied at any temperature in a specific environment. When compared to the pellet technique, DR has the advantage of a larger sample surface area and, hence, more sites for interaction. The small optical path within the chamber minimizes potential spectral interference by the gas during the gas-solid experiment.

The physical state of membranes in the bacterium Acholeplasma laidlawii was investigated by FT-IR spectroscopy. A comparison of the temperature dependence of the infrared spectra of live and lifeless Acholeplasma laidlawii cells reveals that at the temperature of growth, i.e., 37°C, the membranes of live cells have a considerably higher degree of conformational disorder. Furthermore, the thermal response of membranes in live and lifeless cells, as monitored by various infrared spectra parameters, is shown to be quite different.

FT-IR spectroscopy has been used to monitor phospholipid order and melting characteristics as well as protein secondary structure in reconstituted membrane systems. The protein used in the current work is CaATPase, a Calcium-pumping protein isolated from rabbit skeletal muscle. The protein is isolated, purified and reconstituted into phospholipid vesicles of the desired composition. High precision (0.03 cm-1) measurements of the temperature dependence of the acyl chain CH2 stretching frequencies are used to construct melting curves for the various phospholipids used in the current work. The effect of CaATPase on lipid order depends upon the level of unsaturation of the lipid acyl chains, the strongest perturbations being observed for molecules containing one saturated and one unsaturated chain. Use of acyl chain perdeuterated lipids as one component of a binary lipid mixture permits studies of the thermal response of each component in either binary lipid mixtures or ternary complexes composed of two lipids plus protein. The tendencies of this integral membrane protein to preferentially interact with a particular lipid component is noted in several instances.

The reversible, stress induced changes in the vibrational modes of amorphous bisphenol-A polycarbonate films have been determined by polarized FTIR. The change in the polarization of the integrated intensities of each absorption band are consistent with the preferential alignment of the molecular segmental axis parallel to the applied stress in the low strain elastic deformation region. This implies that the stresses are primarily transmitted through the chain backbone. The stress induced dichroism of the assignable modes corresponds to 0.1%/MPa increase in the degree of orientation. The CH bands are not a function of stress and there is a slight stress induced shift in the frequency of the 1081 cm-1 band towards lower energies. These results indicate that the environment of the inplane modes is perturbed and suggests that the stress transmitted through the polymeric backbone partially relaxes the steric constraints that restrict the orientation of the ortho protons of the phenol rings.

The platelet activating factor, PAF, has been recently identified as an ether lipid with dramatic bioreactivity. The present IR spectroscopic investigation demonstrates that in an aqueous environment PAF can assume three different structures, a micellar form at tempera-tures above 21°C, a solid-like opaque lamellar form at temperatures below 12°C, and an intermediate transparent lamellar form that exists at temperatures between 12 and 21°C. The three structures are separated by two reversible phase transitions; however, the rate of the reversed micellar to lamellar change is negatively temperature dependent, i.e., about 6 min at -1°C and 12 min at 3°C, and slower than the lamellar to micellar change.

FT-IR spectra of free lipid A, isolated from Escherichia coli containing C-14 and C-12 acyl chains have been recorded and tentative band assignments were undertaken. The highly complex phase transition behaviour of fully hydrated multibilayer preparations of lipid A has been investigated using temperature-induced frequency shifts, difference spectra and second derivatives of >CH2 asymmetric and symmetric stretching modes near 2918 and 2850 cm -1, respectively. Three "phase transitions" near 22, 34 and 41oC could be detected, the latter being the main transition and - most probably - the familiar B-u-transition. The high value of 41°C found for the main transition temperature may reflect the stability and permeation barrier function of this molecule within the outer membrane of gram-negative bacteria.

Coupled with thin layer chromatography, FTIR Proved to be an accurate, fast, and inexpensive way to monitor and estimate the relative purity of samples of violacein while also providing a procedure for identifying solvent systems which result in optimum separation of the pigment from non-pigment components with maximum speed and reproducibility.

The behaviour of some poly(amido-amine)s either in aqueous solution or grafted on the surface of various materials has been studied by the FTIR technique. Difference spectra of the polymers at different pH's show the presence of different protonated forms. By the same technique the capability of the polymers to form complexes with Cu(II) ion has also been evaluated. Transmittance and ATR FTIR techniques are used for monitoring each chemical step in grafting poly(amido-amine)s chain on the surface of polyurethanes.

FT-IR spectra of ribonuclease A, a small globular enzyme, show the effects of a ribonuclease molecule unfolding and then refolding in deuterium oxide. The deuteration process causes changes in the Amide I and Amide II regions of the spectra that provide information allowing assignment of peaks of the deconvolved Amide I band to secondary structural features.

A procedure is described to subtract the buffer contribution from the infrared spectra of aqueous solutions of proteins using the 2130 cm-1 association band of water as an internal intensity standard. After correction, the spectra of several globular proteins were used to develop a method to evaluate their conformation in solution.

Isotopically labelled polyacrylonitriles have been degraded at 235°C in the presence of 16 e 02 and '802 in order to aid the unraveling of the preox infrared spectrum. Replacing 02 with 1802 as a reactant did not affect the position of the 1595 cm^-1 band. The only oxygen-18 sensitive modes were found between 1800 and 1650 cm^-1. Bands indicative of acids, imides, and pyridone units fused to pyridine rings were detected. The preoxidized powders were subsequently heated in N2 to 750°C. Initially carboxylic acids and imides are lost. Eventually the preox ring vibrations are replaced at higher temperatures by bands at 1600 and 1300 cm^-1. The nature of oxygen in the ring structure of preox is discussed.

We report the successful quantitative determination of small molecules (haptens) to biomacromolecules. Results are shown for two such systems: 7-[4-chloro-3,5-dinitro-benzamido)-deacetoxycephalosporanic acid (CDNB-7-ADCA), coupled to bovine serum albumin, and polyethyleneglycol coupled to ovalbumin. In each case, the number of haptens actually bonded is considerably less than theoretically possible. We also report the successful analysis of three additional systems, but examples of their data are not shown: CDNB-7-ADCA,CDNB, and 3-[CDNB]-2-azetidinone coupled to ovalbumin. In all cases, the fact that pertinent moieties of the hapten are intact indicates that the entire hapten is intact also.

Diffuse reflectance infrared Fourier transform spectroscopy (DRIFT) was used to qualitatively identify organic impurities in sulfur. The impurities were furthur graded by sorbing carbon disulfide (CS2), and measuring the area under the band from 1600 to 1500 cm-1 relative to the sulfur band at 1300 cm-1, as observed in the DRIFT spectrum. The sorption of CS2 was proportional to the amount of organic impurity, was not removed by vacuum at 70 C, and was reproducible whether sorption was by infusion or by exposure to vapor.

Some specimens of gallstones with black colour and pigment gallstones were studied by FT-IR spectroscopy. From the subtraction spectra of the samples using calcium bilirubin as the reference substance, the characteristic bands of the proteins were obtained. Bezoar is the gallstone of ox. It is an important ingredient of some Chinese traditional medicines. Four specimens of natural bezoar produced from different places were studied by FT-IR. From the subtraction spectra of the bezoar samples using calcium bilirubin as the reference, the main bands of protein were also obtained. The secondary structures of the proteins were discussed.

The commonality between ultramicrosampling and GC-IR is far deeper than the desire for picogram detection levels in both cases. Both techniques also need small area light spots: in ultramicrosampling, for spatial resolution; and in GC-IR, to match limited sample volumes. Fast response is needed for real-time measurements on the fly GC-IR, and for mapping analysis of extended samples in a finite line in ultramicro-sampling. And finally, the fly fast processing is required for real-time recognition of significant success in GC-IR (presence of peaks) and in ultramicrosampling (presence of local anomalies in sample). A small FT-IR interferometer benefiting from the counter-Jacquinot advantage (and some less awkward nomenclature is clearly required here), immersion optics for microsampling and optimized sample cells for GC-IR, high efficiency sources and detectors (and detector electronics!), and the systematic application of information,theory to data processing algorithms can be used to bring both these techniques into the middle picogram domain. Progress from here will require cryogenic sampling GC-IR (giving only small improvements over an optimized light pipe) or non FT-IR techniques, such as grating (shudder!) scanned CO2 lasers (capable of a >100 fold gain).

An internal reflection spectroscopy (IRS) element may be modified by application of thin layers of metal oxides, aramids or carbonised polymers, so that it resembles chemically the surface of reinforcements (eg. glass, carbon, Kevlar) used in the production of reinforced plastics. The first 0.2-1 µm (depending on wavelength) of polymer matrix adjacent to the modified surface may then be examined by FT-IR, using "windows" in the spectra of the coatings. In this way the simulated reinforcement surfaces are shown to modify the chemistry of the thin layer of polymer matrix adjacent to the surface (ie. the interphase). These chemical differences are shown to correlate with property differences in reinforced plastics.

Headspace analysis is an equilibrium sampling method which involves injeTting the vapor phase of a sample which has been warmed in a sealed vial into a gas chromatograph . This can lead to substantial sensitivity enhancements for volatile components, and can remove the volatiles from non-chromatographable matrices. The combination of headspace gas chromatographic analysis and FT-IR can provide a powerful tool for the identification of volatile organics in a variety of matrices. It also has the potential to enhance GC/FT-IR sensitivity by 1-2 orders of magnitude.

A wide range of samples have been studied by TGA/FT-IR, using a mobile, low-cost FT-IR spectrometer coupled to a standard TGA. Much qualitative information can be obtained about the thermal properties of a sample. We have also achieved success at quantitating the evolution of some gases, namely sulfur and carbon dioxides, by observing the decomposition of reference samples.

Supercritical fluid chromatography (SFC) permits nonvolatile or thermally labile compounds to be separated at high resolution without necessarily using a mobile phase which is liquid at atmospheric pressure or room temperature. The most common mobile phase to date has been carbon dioxide, at a pressure above about 1000 p.s.i. and a temperature above 35°C. Both packed columns of the type used for high performance liquid chromatography (HPLC) and wall coated open tubular (WCOT) capillary columns of the type used for high resolution gas chromatography (GC) can be used. In this paper, we report the on-line measurement of infrared spectra of peaks eluting from SFC columns using two approaches: 1) By passing the effluent from the column directly through a flow cell; 2) By eliminating the mobile phase while depositing the solute on KC1 powder prior to measuring its diffuse reflectance (DR) spectrum.

Rapid-scan time-resolved Fourier-transform infrared (FT-IR) spectroscopy is a method that allows one to examine the changes in the infrared spectrum of a system undergoing a chemical or physical change. This method exploits the inherent multiplex advantage of FT-IR; each scan of the FT-IR spectrometer yields the entire infrared spectrum of the sample at the time the scan is taken. Clearly, a time-resoved infrared spectrum can be obtained by storing each scan in a separate computer file. The degree of time resolution is limited by the speed at which the interferometer mirror can be moved and the data system can acquire and store spectral data. At medium spectral resolution (16 cm-1), time resolutions of 12-15 milliseconds are possible using commercially available instrumentation and software, that is, interferograms may be collected and stored at a rate of 65-85 scans per second (1).

Polyacetylene (PA) is the prototype of polimeric compounds which ,when doped, become highly conducting. The origin of the electrical conductivity in this and other similar organic polymers is not yet known, in spite of the great efforts made by experimentalists and theoreticians in the fields of chemistry and physics.

Quantitative analysis of multicomponent systems is often hindered by deviations from linear Beer's Law behaviour. Attempts to accommodate non-linearity have generally assumed some explicit relationship between absorbance and concentration,l. An alternative approach is to consider the deviations from Beer's Law as arising from a series of additional spectral components. Such a model has obvious physical significance when there are specific interactions between the components in a mixture, and may prove a useful approximation in any situation. On the basis of this model it will be shown that least squares curve fitting can give accurate quantitative results even when there are gross deviations from Beer's Law.

Near millimetre wavelength studies of the complex refractive indices of ferrofluids by dispersive Fourier transform spectroscopy have allowed their magnetic field - induced birefringence and dichroism to be investigated. The results will be discussed in relation to optical studies and to near millimetre wavelength modulation experiments with these fluids.

Analog-to-digital converters (ADCs) are an indispensible component in the electronic processing chain of modern computer-ized instruments, such as Fourier transform infrared (FT-IR) spectrophotometers. In an FT-IR spectrometer, the interferogram of a broadband source covers a wide dynamic range, on the order of 106:1. This is a very demanding application for a high-speed ADC. Since FT-IR spectroscopy carries the promise of achieving high accuracy, all possible sources of systematic errors must be examined in order to validate that promise'. We will show that linearity errors in the ADC can result in a distortion of the transformed spectrum. This distortion can lead to significant systematic inaccuracies in FT-IR spectrophotometry.

The pressure dependence of infrared spectra has been measured for several gas and liquid phase hydrocarbon systems. Band position and intensity have been correlated with pressure for methane, carbon dioxide, n-pentane, n-hexane, and n-decane as well as mixtures thereof. The feasibility of using infrared on high pressure (up to 5000 psi) mixtures for compositional analysis has been demonstrated.

The IR spectral assignments for HAN and HAN-d4 were reexamined and found to be more con-sistent with earlier rather than more recent interpretations. High-rate thermolysis of HAN at elevated pressure reveals an oscillating reaction in the initial stage.

Multicomponent analysis of optical spectra can be optimized by processing the spectral data in the Fourier domain. The transform makes it possible to take maximum advantage of the informational content of the spectra while reducing the data storage requirements and processing time. The transformed spectra are stored and processed as vectors. We have explored methods for selecting the "best" set of vector representations. During this investigation, we found that any number of chemical interferences can be accounted for in the vector representations without knowing the types of concentrations of these components. The methodology greatly expands the capabilities of multicomponent analyses as will be demonstrated on both infrared and uv-visible spectra.