Showing papers on "Infrared spectroscopy correlation table published in 1998"

Surface enhanced infrared absorption spectroscopy (SEIRA) using external reflection on low-cost substrates

Abstract: A novel approach for spectroscopic trace analysis is introduced by combining surface enhanced infrared absorption (SEIRA) spectroscopy with external reflection techniques on disposable inexpensive substrates. SEIRA-active surfaces produced by electrochemical deposition of silver on smooth metal surfaces and glass improve the sensitivity of IR reflection measurements significantly since the infrared absorption of organic substances such as p-nitrobenzoic acid is considerably increased in the vicinity of rough noble metal surfaces. The enhancement properties of thus prepared substrates are characterized and compared using IR-spectroscopy. These low-cost substrates used in single- and multiple external reflection arrangements, respectively, yield a significant increase of the detection level compared to conventional reflection absorption infrared spectroscopy (RAIRS) up to one order of magnitude. Hence, a notable step towards a wide-spread application of SEIRA in routine IR reflection analysis is presented.

FT-IR and FT-NIR Raman spectroscopy in biomedical research

Abstract: FT-IR and FT-NIR Raman spectra of intact microbial, plant animal or human cells, tissues, and body fluids are highly specific, fingerprint-like signatures which can be used to discriminate between diverse microbial species and strains, characterize growth-dependent phenomena and cell-drug interactions, and differentiate between various disease states. The spectral information potentially useful for biomedical characterizations may be distributed over the entire infrared region of the electromagnetic spectrum, i.e. over the near-, mid-, and far-infrared. It is therefore a key problem how the characteristic vibrational spectroscopic information can be systematically extracted from the infrared spectra of complex biological samples. In this report these questions are addressed by applying factor and cluster analysis treating the classification problem of microbial infrared spectra as a model task. Particularly interesting applications arise by means of a light microscope coupled to the FT-IR spectrometer. FT-IR spectra of single microcolonies of less than 40 μm in diameter can be obtained from colony replica applying a stamping technique that transfers the different, spatially separated microcolonies from the culture plate to a special IR-sample holder. Using a computer controlled x,y-stage together with mapping and video techniques, the fundamental tasks of microbiological analysis, namely detection, enumeration, and differentiation of micro-organisms can be integrated in one single apparatus. Since high quality, essentially fluorescence free Raman spectra may now be obtained in relatively short time intervals on previously intractable biological specimens, FT-IR and NIR-FT-Raman spectroscopy can be used in tandem to characterize biological samples. This approach seems to open up new horizons for biomedical characterizations of complex biological systems.

Infrared absorption cross-sections and integrated absorption intensities of HFC-134 and HFC-143a vapour

Abstract: Infrared absorption cross-sections and integrated absorption intensities of HFC-134 (1,1,2,2-tetrafluoroethane) and HFC-143a (1,1,1-trifluoroethane) vapour have been determined from laboratory measurements at six temperatures (203, 213, 233, 253, 273 and 297 K) for the region 560–1900 cm −1 (5.3–17.9 μm) at 0.03 cm −1 instrument resolution, by Fourier transform infrared spectroscopy. In addition, air-broadened spectra have been recorded at 297 K and pressures of 5, 20 and 100 kPa air. Inter-comparisons between this work and previous studies have been made where possible.

Infrared matrix isolation and DFT study of NiN2

Abstract: The infrared spectrum of NiN 2 isolated in solid argon at low temperature has been reinvestigated. New isotopic data on ν 1 , ν 2 , ν 3 , ν 1 + ν 2 and 2 ν 1 , have been gathered in the near- and far infrared regions. This information has led to a reassignment of the metal-ligand vibrations, and, consequently, to a reassessment of the Ni–N bond force constant which is in good agreement with previous theoretical predictions on NiN 2 . Density Functional calculations of the geometrical, electronic and vibrational properties of NiN 2 are also presented and compared to the experimental values.

Two-dimensional near infrared correlation spectroscopy: principle and its applications

Abstract: The basic principle and applications of generalised two-dimensional (2D) near infrared (NIR) correlation spectroscopy are reviewed in this paper. A brief history and the basic principle of 2D correlation spectroscopy are described first, and then its importance for NIR spectroscopy is discussed. An outline of the mathematical treatment of generalised 2D correlation spectroscopy is given. Several examples of generalised 2D NIR and 2D NIR-mid IR (MIR) heterospectral correlation analysis are introduced.

Real-Time Polarization Modulation in Situ Infrared Spectroscopy Applied to the Study of Atmospheric Corrosion:

Abstract: A new methodology for the real-time in situ monitoring of atmospheric corrosion processes is presented. The mid-infrared spectra of surface films formed on polished copper substrates exposed to humid air containing sub-ppm levels of sulfur dioxide, nitric oxide, and hydrogen chloride were obtained by using a novel surface-sensitive infrared technique: real-time polarization modulation grazing angle reflection-absorption spectroscopy. The new methodology demonstrated improved signal-to-noise ratios, by a factor of 2.5, as compared to conventional Fourier transform infrared reflection absorption spectroscopy. Molecular spectroscopic data for water- and hydroxyl-containing species present at the metal surface were obtained with no interference from water vapor. Over the spectral region 4000-800 cm-1, bands were identified and assigned to nitro and nitrito adsorbates, to sulfite ions, and to bound water on the copper surface. Analysis of the time evolution and the profile composition of these bands is possible because of the sensitivity of this new optical sampling technique.

Improved Experimental Energy Levels of Carbon I from Solar Infrared Spectra

Abstract: We have improved the energy levels in neutral carbon using high resolution infrared solar spectra. The main source is the space-based ATMOS spectrum measured by the Fourier transform spectroscopy technique from 600 to 4800cm-1. From these infrared data, we have determined 19 new energy levels in the 5f, 5g, 6g and 6h configurations. To extend measurements to higher frequencies, we also use other FTS solar spectra: the MARK IV balloon data, covering from 4700 to 5700cm-1, and the ground-based NOAO spectra, up to 9000cm-1 of Livingston and Wallace and 8900 to 13600cm-1 of Wallace et al. For completeness' sake, we include the 63 new levels found by Feldman et al. plus 8 new levels derived from the VUV data. Utilizing all existing carbon spectra from the far infrared to the vacuum ultraviolet, we have revised Johansson's energy levels and the ionization potential, resulting in improving the accuracy by about an order of magnitude to about 3mK.

Theoretical determination of parameters for optimum surface specificity in overlayer attenuated-total-reflection infrared spectroscopy

Abstract: We investigate the feasibility of overlayer attenuated-total-reflectance (O-ATR) infrared spectroscopy as a surface analytical tool for studying reactions and molecular properties of adsorbates at surfaces exposed to aqueous nonelectrolyte solutions. Through modeling an O-ATR system by assuming it to comprise three, four, or n phases of homogeneous refractive index, one can use an electric-field analysis to determine how the parameters of adsorption free energy, overlayer thickness, initial angle of incidence, and internal-reflection element refractive-index influence solvent-subtracted O-ATR infrared-absorption spectra. The theory behind such an analysis is explained, and the results of its application are presented for hypothetical O-ATR systems consisting of either a zinc selenide or a germanium internal-reflection element, an iron or hematite overlayer, an adsorbate layer, and a solution of methylene chloride in water.

Infrared Spectroscopy of the Solid Solution [KxNa1-x]2CO3

Abstract: A complete infrared study of the mixed crystal systems K2CO3 and Na2CO3 has been carried out in the region of 4000–600 cm-1. The study includes the internal fundamental normal vibrations of the CO3 ion in the ordered phases of the two carbonates at room temperature for different values of potassium concentration. The IR spectra, spectral band shape intensities and frequencies of the internal modes have been studied as a function of the potassium ion concentration.

Infrared spectroscopy and microscopy at the Daresbury synchrotron light source (

Abstract: The design criteria used in the development of IR station 13.3 at the Daresbury SRS are reviewed particularly in terms of its principle application to reflection-absorption infrared spectroscopy (RAIRS). An example of current performance is given in the form of a RAIR spectrum of chlorine atoms adsorbed on Ag (100). The application of the station to infrared microscopy is reviewed and IR spectra from a thin polymer laminate are used to compare performance with that using a conventional infrared source.

Infrared OH− absorptions in Sr0.61Ba0.39Nb2O6 crystals

Abstract: The infrared OH− absorptions in Bridgman grown Sr0.61Ba0.39Nb2O6 crystals have been investigated by Fourier transform infrared spectroscopy. Crystals exhibited typical O–H stretching vibrations near ν=3500 cm−1 (λ≈2.87 μm). The polarization dependent absorption measurements revealed that a greater density of O–H bonds are polarized in the a−b plane with a smaller amount of bonds along the c axis. Protons (H+), which prefer a specific site at room temperature, tended to occupy different sites as the temperature increased. As-grown crystals contained protons on the order of 1017 cm−3, and the proton concentration increased by approximately 1 order of magnitude after heat treatment in a humid atmosphere.

Determination of shallow dopants in silicon by low-temperature FTIR spectroscopy

Abstract: The shallow dopants B, P, Al, As, and Sb in Si have been investigated by low-temperature Fourier-transform infrared absorption measurements. Experimental procedures are described to obtain quantitative results for the B and P concentration with improved precision. New calibration factors, based on a correlation with four point probe resistivity measurements, are given which can be used in the concentration range from 1010 to 1016 cm−3. Preliminary results are reported for Al, As, and Sb.

Infrared absorption from LiF nanocluster-assembled films

Abstract: Infrared absorption spectra are reported for LiF nanocluster-assembled films. Multi-order infrared absorption and surface modes are observed. Infrared peaks are identified and discussed in terms of macroscopic and microscopic theories that have been used to describe the lattice dynamics of small crystals. Good agreement is achieved between the observed spectral peaks and the calculated results.

Molecular Spectroscopy with ISO

Abstract: In spite of the important astrophysical output that could be obtained from infrared observations, the wavelength range 2-200 μm has remained poorly studied due to the absorption of radiation produced by the Earth’s atmosphere The spectrometers on board the Infrared Space Observatory (ISO) provide a unique opportunity to study important molecular species through transitions which are inaccessible from the ground or airborne platforms The ISO spectrometers offer the possibility to detect, with a reasonably good spectral resolution, the ro-vibrational transitions of important molecules The SWS spectrometer cover the region 2-45 μm and it is well adapted to the study of ro-vibrational transitions (stretching and bending modes) while the LWS spectrometer provides a powerful tool to observed the pure rotational transitions of light species like H2O In this review we present the main results on gas phase molecules obtained with the ISO-SWS and ISO-LWS spectrometers and also the low resolution CVF-ISOCAM spectrometer