Showing papers in "Applied Spectroscopy in 1979"
TL;DR: In this article, the prominent lines of 70 elements as emitted in an inductively coupled plasma excitation source have been identified and the lines are listed alphabetically by element and numerically by wavelength.
Abstract: The prominent lines of 70 elements as emitted in an inductively coupled plasma excitation source have been identified. The lines are listed alphabetically by element and numerically by wavelength. Detection limit capabilities are estimated for each spectral line.
391 citations
TL;DR: In this paper, the location of the characteristic IR absorption bands, in the low frequency region (<600 cm−1), which could be used as fingerprints in the identification of hematite, was investigated.
Abstract: Hematite, α-Fe2O3, one of the most abundant forms of iron oxides in this planet, has been studied and used since ancient times. A search through the pertinent literature reveals many discrepancies on the location of the characteristic IR absorption bands, in the low frequency region (<600 cm−1), which could be used as fingerprints in the identification of hematite. For example, McDevitt and Baun characterize hematite by maxima at 325, 370, 468, and 560 cm−1. Liese, however, locates absorption bands at 312, 391, 449, and 532 cm−1. Schwertmann and Taylor locate them at 345, 470, and 540 cm−1 whereas Bogdanovich et al. assign bands at 475, 520, and 580 cm−1 as characteristic for hematite. It seems that in addition to isomorphous substitution and impurities, crystal defects and the degree of crystallinity may also cause the differences in the locations of the absorption bands. The present work was undertaken to examine the latter assumption and to determine whether IR spectroscopy can be applied to distinguish between well and poorly crystalline hematites.
105 citations
TL;DR: Induction-coupled plasma atomic-emission spectrometry offers an ideal method for simultaneous multielement analysis of natural water samples as mentioned in this paper, and the Water Resources Division of the U.S. Geological Survey employs this technique for quantitative analysis of 17 major and trace constituents.
Abstract: Induction-coupled plasma atomic-emission spectrometry offers an ideal method for simultaneous multielement analysis of natural water samples. The Water Resources Division of the U.S. Geological Survey currently employs this technique for quantitative analysis of 17 major and trace constituents. These include analysis of Ba, Be, Cd, Co, Cu, Fe, Pb, Li, Mn, Sr, Mo, V, Zn, Ca, Mg, Na, and SiO2 in a routine production mode, in which an excess of 1000 determinations can be made in a normal working day. Comparability studies with conventional single-element methods of analysis, such as atomic absorption spectrometry and colorimetric techniques, show essentially equivalent accuracy and precision, frequently at much higher sensitivity.
102 citations
TL;DR: Spectral line broadening and radiative electron-ion recombination processes may make significant contributions to the total spectral background level when inductively coupled plasma excitation sources are observed with spectrometers having low stray light levels.
Abstract: Spectral line broadening and radiative electron-ion recombination processes may make significant contributions to the total spectral background level when inductively coupled plasma excitation sources are observed with spectrometers having low stray light levels. These background contributions are more easily identified in inductively coupled plasma discharges because of their stable background level and by the fact that net analyte line intensities are affected to such a small degree by changes in the concentration of concomitants. The wings of collisionally broadened lines may produce significant background changes at wavelengths removed 10 nm from the parent line center. For some elements such as Mg, linear Stark-broadened lines produced spectral background at unexpectedly large displacements from the line center. The radiative Al ion-electron recombination continuum produces a greater than tenfold increase in the background from ~210 down to 193 nm at Al solution concentration of 2500 μg/ml. Thus, a solution containing only 250 μg/ml of Al will cause an ~100% increase in the background level below 210 nm over that measured when deionized water is nebulized into the plasma.
99 citations
TL;DR: In this article, a general method for direct measurement of differential absorption intensities using a Fourier transform infrared spectrometer is described, and specific expressions are presented for the measurement of circular and linear dichroism.
Abstract: A general method for the direct measurement of differential absorption intensities using a Fourier transform infrared spectrometer is described. The differential intensities must be higher in frequency than the interferogram frequencies and may arise from a periodic variation of the absorption strength of the sample, or by dichroic response of the sample to alternate states of polarization of the infrared beam. Specific expressions are presented for the measurement of circular and linear dichroism. These expressions represent an extension of the Grosjean-Legrand polarization modulation technique to Fourier transform interferometry.
94 citations
TL;DR: The feasibility of applying the methods of factor analysis to Fourier transform infrared spectra is examined in this article, where the method is designed to determine the number of components contributing to a spectral region.
Abstract: The feasibility of applying the methods of factor analysis to Fourier transform infrared spectra is examined. The method is designed to determine the number of components contributing to a spectral region. The technique has been applied to a model system consisting of solutions of p-, o-, and m-xylenes. The method has also been used for calculating the number of independently absorbing species in several polymer systems. Spectral requirements and the general applicability of factor analysis are also discussed.
78 citations
IBM1
TL;DR: In this paper, it has been shown that compared to a bulk sample the scattering volume in the thin film has increased by 1 to 2 orders of magnitude which results in a Raman spectrum with considerably higher signal/noise ratio.
Abstract: Raman spectroscopy of polymer films using integrated optics has been shown to be a general technique applicable to films with thicknesses as small as 1 μ. With this technique no apparent interference from spectral features due to the substrate has been observed. It has been shown that compared to a bulk sample the scattering volume in the thin film has increased by 1 to 2 orders of magnitude which results in a Raman spectrum with considerably higher signal/noise ratio.
69 citations
TL;DR: Infrared spectral searches which rely on detailed intensity information and those based on peak position information are compared using a library of 500 reference spectra to assess the effects of selecting data from limited regions of the infrared spectrum.
Abstract: Infrared spectral searches which rely on detailed intensity information and those based on peak position information are compared using a library of 500 reference spectra. Spectra with detailed intensity information are encoded with absorbance values for 200 resolution increments spanning the range from 4000 to 200 cm−1. Three different distance metrics are evaluated for searches using intensity information, and the effects of selecting data from limited regions of the infrared spectrum are examined.
53 citations
TL;DR: A comparison of an end-on viewed argon inductively coupled plasma (ICP) operated in the horizontal position with the conventional side-on-viewed argon ICP was carried out using the same experimental setup as discussed by the authors.
Abstract: A comparison of an "end-on" viewed argon inductively coupled plasma (ICP) operated in the horizontal position with the conventional "side-on" viewed argon ICP was carried out using the same experimental setup. The end-on ICP required an air cutoff stream located toward the tip of the luminous discharge, to protect the optics and to increase linearity ranges, and the orifice diameter of the central tube of the torch was widened to 1.9 mm, to improve line/background ratios. With the end-on viewed plasma the linearity ranges, the susceptibility to solute vaporization and to ionization matrix effects, and the detection limits in an organic solvent were insignificantly different from those observed with the side-on viewed plasma. Detection limits with aqueous samples were always significantly lower with the end-on viewed plasma, usually five- to tenfold lower, in a few instances, 20-fold lower. With the end-on viewed plasma the optimal observation region for both single and simultaneous multielement analysis is one and the same and is extremely easy to locate.
48 citations
TL;DR: In this article, the Fourier transform infrared spectrum of atactic poly(methyl methacrylate) (PMMA) is compared with that of PMMA labeled with 18O in the ester groups.
Abstract: Fourier transform infrared spectrum of atactic poly(methyl methacrylate) (PMMA) is compared with that of atactic PMMA labeled with 18O in the ester groups. The results obtained define the assignment of the bands associated with vibrations of the ester groups of PMMA. Furthermore, the Fourier transform infrared spectroscopy provides a simple method for obtaining the spectra of "pure" derivatives containing 18O.
48 citations
TL;DR: In this paper, the C-H stretching and bending vibrations of the methylene, α-methyl, and ester methyl groups of poly(methyl methacrylate) are discussed and assigned on the basis of the infrared spectra of its three deuterated derivatives: PMMA-CD2-OCD3, PMMA--CD2, OCD3, and PMMA
Abstract: The C—H stretching and C—H bending vibrations of the methylene, α-methyl, and ester methyl groups of poly(methyl methacrylate) are discussed and assigned on the basis of the infrared spectra of its three deuterated derivatives: PMMA—CD2—OCD3, PMMA—CD2—OCD3, and PMMA—CD2—CD3. The digital analog of PMMA is obtained by coaddition of the Fourier transform infrared spectra of the deuterated PMMA derivatives. The experimental and digital PMMA spectra are compared in the regions of the C—H stretching and C—H bending vibrations: the agreement in frequency is excellent and the relative intensities are practically the same in the C—H stretching vibrations region. However, their relative intensities strongly differ in the C—H bending region.
TL;DR: The majority of the plasma lines of the argon ion laser are shown to be transitions of the gas ion as discussed by the authors and these lines are useful for calibrating Raman spectrometers, including relative intensities, wavelengths and wavenumber shifts relative to the 488.0 and 514.5 nm laser lines.
Abstract: The majority of the plasma lines of the argon ion laser are shown to be transitions of the argon ion. These lines are useful for calibrating Raman spectrometers. A table is given of the plasma lines, including relative intensities, wavelengths (in standard air), wavenumber (in vacuo), and wavenumber shifts relative to the 488.0 and 514.5 nm laser lines. Spectra showing the relative intensities of these lines are also shown.
TL;DR: In this article, the effectiveness of interference filters for reduction or elimination of stray light effects in optical spectrometers employed for trace atomic emission analyses is discussed. But the authors focus on those analyte species that contribute significant stray light at wavelengths far removed from the offending radiation.
Abstract: Quantitative data are presented on the effectiveness of interference filters for reduction or elimination of stray light effects in optical spectrometers employed for trace atomic emission analyses Specific attention is focused on those analyte species that contribute significant stray light at wavelengths far removed from the offending radiation For simultaneous multielement determinations with a polychromator, band reflection filters are shown to provide an attractive means of eliminating stray light effects arising from the very intense Ca lines emitted in an inductively coupled plasma For the spectrometers used in the present study, a major fraction of the background shifts caused by changing concentrations of Mg arose from real background contributions rather than from stray light
TL;DR: In this paper, the performance of inductively coupled plasma spectrometry was evaluated for multielement analysis at submicrogram levels in geologic materials and the experimental and operating parameters for the analyses of trace metals found in the organic phase following a rapid and efficient extraction technique.
Abstract: The expanding need for multielement analysis at submicrogram levels in geologic materials has prompted an increased interest in inductively coupled plasma spectrometry. No other analytical procedure simultaneously exhibits, to the same degree, the operating characteristics of excellent precision and accuracy, low limits of detection, dynamic concentration ranges in addition to eliminating or at least reducing, interelemental and matrix effects. The experimental and operating parameters are described for the analyses of trace metals found in the organic phase following a rapid and efficient extraction technique. Direct spectral interferences, matrix and interelemental effects caused by major elements in geologic materials are effectively eliminated and sensitivity is increased by concentrating the trace metals in the organic phase. Aluminum, calcium, iron, potassium, magnesium, manganese, and sodium are among the major elements eliminated; and trace elements (Ag, Au, Bi, Cd, Cu, Pb, and Zn) critical to a mineral evaluation, some of which have insufficient detection limits by plasma analyses, are enhanced to a more precise detection level.
TL;DR: In this paper, the authors used reflection-absorption infrared spectroscopy and ellipsometry to determine the structure of films formed by an epoxy resin adsorbed from solution onto polished iron and copper mirrors.
Abstract: Reflection-absorption infrared spectroscopy and ellipsometry have been used to determine the structure of films formed by an epoxy resin adsorbed from solution onto polished iron and copper mirrors. Films only about 15 A thick were obtained. The infrared spectra of these films were characterized by absorption bands near 1500 and 1240 cm−1. Consideration of the thickness of the adsorbed films as well as wetability, surface coverage and the relative intensities of the bands near 1500 and 1240 cm−1 indicates that the epoxy resin molecules are probably adsorbed with a vertical conformation where only a single oxirane oxygen atom is in contact with the surface.
TL;DR: In this article, a new nebulizer developed for direct atomic absorption analysis of extremely complex clinical and environmental materials is described. But the design and performance of the nebulizers based on the Babington principle are discussed.
Abstract: Studies are presented to characterize a new nebulizer developed for direct atomic absorption analysis of extremely complex clinical and environmental materials. Important parameters are described concerning the design and performance of "high solids" spectrochemical nebulizers based on the Babington principle. A new simplified design is presented and mechanisms of undesirable sample wastage are considered. Data are presented concerning the effect of impaction on conventional and "high solids" aerosol generation.
TL;DR: In this article, a general spectroscopic method for the analysis of mixtures that does not require external calibration has been developed, based on the obtaining of absorbance ratio spectra and the determination of a concentration ratio at frequencies unique to each component.
Abstract: A general spectroscopic method for the analysis of mixtures that does not require external calibration has been developed. The method is based on the obtaining of absorbance ratio spectra and the determination of a concentration ratio at frequencies unique to each component. The method is applied to mixtures hexane and cyclohexane.
TL;DR: In this article, an improved NaBH4 reduction of soluble arsenite to form arsine as a preconcentration approach for ultra-trace level arsenic determination by inductively coupled plasma optical emission spectrometry is described.
Abstract: Studies are presented describing an improved application of the NaBH4 reduction of soluble arsenite to form arsine as a preconcentration approach for ultra-trace level arsenic determination by inductively coupled plasma optical emission spectrometry. Specialized analyte introduction techniques are described for elimination of reaction by-products that would normally extinguish a medium power plasma discharge. An approach is presented to minimize the need for background correction and facilitate a superior arsenic detection limit (≤0.03 ng/ml) in a relatively inexpensive 1.2 kW inductively coupled plasma system.
TL;DR: In this paper, the authors demonstrate that residual peaks can arise from optical phenomena based solely on the effects of differences in the real part of the refractive indices of the pure components.
Abstract: Calculations of infrared difference spectra of polymer blends and pure components have been made based on models with no intermolecular bonding interactions. The results demonstrate that residual peaks can arise from optical phenomena based solely on the effects of differences in the real part of the refractive indices of the pure components. Accordingly, chemical interpretations, such as intermolecular bonding interactions, of residual difference peaks must be made with caution in blends where the real refractive indices of the components differ by several percent or more in absorption-free energy regions.
TL;DR: In this article, a comparison is made of interferences in pulse-type vs. constant temperature atmoziers for various metal chlorides on the Mn atomic absorption signal, and it is proposed that the observed differences are due mainly to the rate at which volatilized analyte attains atomization temperature and the residence time in the hot environment.
Abstract: The application of electrothermal atomization techniques for atomic absorption spectroscopy has increased many fold in recent years. Along with this widespread application, matrix interferences in pulse-type electrothermal atomizers have been observed. Until recently, very few interference studies have involved constant temperature electrothermal atomizers. In this paper a comparison is made of interferences in pulse-type vs constant temperature atmoziers for various metal chlorides on the Mn atomic absorption signal. The results show no interferences in the constant temperature system while significant matrix interferences are observed in the pulse type unit. It is proposed that the observed differences are due mainly to the rate at which volatilized analyte attains atomization temperature and the residence time in the hot environment.
TL;DR: In this article, a technique for rapid acquisition and computer processing of Raman signals is described for probing premixed laminar hydrocarbon-air flames using laser Raman spectroscopy.
Abstract: A technique for rapid acquisition and computer processing of Raman signals is described for probing premixed laminar hydrocarbon-air flames using laser Raman spectroscopy. Temperatures can be determined to within ±50°K by fitting the observed N2 spectrum at any point in the flame. Fits to the spectra of O2, CO, H2, and CO2 are used to measure their mole fractions at the calculated N2 temperature. For the remaining polyatomic species, the total area under the peak is the primary measure of their concentration.
TL;DR: In this paper, the radiofrequency (rf) inductively coupled plasma (ICP) has become a widely used tool for multielement atomic emission analysis, where the excitation mechanisms have been shown to be different from those in flames.
Abstract: The radiofrequency (rf) inductively coupled plasma (ICP) has become a widely used tool for multielement atomic emission analysis. Investigation of excitation processes in spectroscopic systems is very important for the full realization of the analytical utility of any new tool. This is particularly true in the case of plasma sources, where the excitation mechanisms have been shown to be different from those in flames. Mermet and Trassy designed a special rf plasma torch atomic absorption measurement, and Wendt and Fassel determined elements which are strong monoxide formers by atomic absorption measurements in an rf plasma. Using electrodeless discharge lamps as the primary excitation source, Montaser and Fassel reported atomic fluorescence in the ICP tail plume (3 to 5 cm above coil). Higher signals for fluorescence than emission were obtained for cadmium, zinc, and mercury, but a special torch configuration was required.
TL;DR: In this article, an ESCA and AES study of the corrosion of 1:1 Pb-Sn solder is reported, where the solder was reacted at room temperature with O2 (1 Torr), H2O (10 Torr) and 100 ppm of NO2 in N2 ( 1 atm), and the latter at 50% relative humidity.
Abstract: An ESCA and AES study of the corrosion of 1:1 Pb-Sn solder is reported. The solder was reacted at room temperature with O2 (1 Torr), H2O (10 Torr), 100 ppm of NO2 in N2 (1 atm), and the latter at 50% relative humidity. Pb and Sn foils were examined under similar conditions. The Pb/Sn ratios observed by ESCA and AES for unmelted solder are close to those expected from bulk composition. After melting, a 50% decrease in Pb/Sn was obtained by ESCA; no AES signal for Pb was observed. Before melting, 90% of the Pb and 100% of the Sn were oxidized; after melting 18% Pb and 70% Sn were oxidized. Exposure of solder to O2 (1 Torr) resulted in a Pb/Sn ratio which decreased as a function of time to a minimum value, rapidly increased through a maximum around 60 min and then decreased to an equilibrium value. The O/(Pb + Sn) ratio increased rapidly to an equilibrium value. The interaction of solder with 10 Torr of H2O vapor for 5 min resulted in surface enrichment of Sn with the formation of Sn and Pb oxides. The results obtained with dry NO2 were similar to those with O2; Pb/Sn decreased rapidly to a minimum and went through a small maximum to an equilibrium value. The distribution of species determined by ESCA before and after the reaction were essentially the same as for O2 except the oxidation of Pb was suppressed. No nitrogen species were observed. Solder exposed to at 100 ppm of NO2 in N2 50% relative humidity gave similar results to O2 and dry NO2. The Pb/Sn maximum occurred at a reaction time approximately 2 to 3 times that of O2 and dry NO2 (40 to 60 min). Two nitrogen species were observed for solder treated with 100 ppm of NO2 in N2 at 50% relative humidity; binding energies were ~404 and 400 eV. These have been attributed to NO2− and NO−, respectively. Mechanisms are proposed for reaction of solder with O2, dry NO2, and NO2 at 50% relative humidity.
TL;DR: In this paper, a multidimensional vector approach is used to form compound-specific vectors from the interferograms of mixture components, which are then compared with a set of known compound vectors by calculating how close together any two vectors lie in space.
Abstract: A compound identification system for gas chromatography/Fourier transform infrared spectroscopy data has been developed based on the direct comparison of interferograms. A multidimensional vector approach is used to form compound-specific vectors from the interferograms of mixture components. Comparisons are made with a set of known compound vectors by calculating how close together any two vectors lie in space. This system is used to identify the components of several synthetic mixtures.
TL;DR: The relative ease of operation, power handling capabilities, and overall performance of an inductively coupled plasma-optical emission spectrometer depends upon numerous factors, not the least of which is the design of the torch as discussed by the authors.
Abstract: The relative ease of operation, power handling capabilities, and overall performance of an inductively coupled plasma-optical emission spectrometer depends upon numerous factors, not the least important of which is the design of the torch. A variety of such designs has appeared in the literature. Most workers have employed three concentric fused silica and/or Pyrex tubes, referred to as an inner sample gas tube, a "flaired mouth" plasma gas tube, and an outer coolant tube. These tubes are either fused into one- or two-piece units through glass blowing techniques or mounted in some type of dismantleable base assembly.
TL;DR: The most promising Zeeman atomic absorption spectrometer employs a variable magnetic field applied to the atomizer and directed parallel to the optical axis as mentioned in this paper, which corrects for background absorption.
Abstract: Analytical curves have been calculated for different Zeeman atomic absorption spectroscopy (AAS) systems which all correct for background absorption. The sensitivity and curvature of the analytical curves have been compared mutually and to normal AAS. A variable magnetic field is preferred over a constant field. In the variable field sensitivity and curvature are equal to normal AAS whereas in the constant field sensitivity is lower and curvature is stronger compared to normal AAS. Whenever a constant magnetic field is used it should be adjustable to the magnetic field strength where maximum sensitivity is obtained. The magnetic field should be applied to the atomizer to achieve correction for wavelength dependent background absorption. The most promising Zeeman atomic absorption spectrometer employs a variable magnetic field applied to the atomizer and directed parallel to the optical axis.
TL;DR: Spectral interferences associated with a direct current plasma combined with a 20-element, direct reading echelle spectrometer have been characterized in this article, and the results indicate that molecular emission interferences due to entrained air are generally negligible, but the presence of high carbon concentrations may cause problems for two elements.
Abstract: Spectral interferences associated with a direct current plasma combined with a 20-element, direct reading echelle spectrometer have been characterized. The results indicate that molecular emission interferences due to entrained air are generally negligible, but the presence of high carbon concentrations may cause problems for two elements. Spectral interferences due to the presence of high concentrations (500 mg/l) of Ca, K, Mg, and Na were also studied. No problems were noted for Na or K while an interference due to atomic emission of Mg was observed. Calcium was responsible for stray light interferences due to near scatter and to reflections occurring in the secondary optics. The latter were eliminated by masking techniques and the former were compensated for via the use of a simple procedure. Overall, the spectral interferences encountered appear to be less severe than those reported for an inductively coupled plasma-direct reading spectrometer system.
TL;DR: In this paper, a least square fitting method for fixed-crystal spectrographs is presented, including flat and convex-curved crystals in reflection mode, with both flat and cylindrical film.
Abstract: Fixed-crystal spectrographs must be calibrated in terms of wavelength vs position on the film or detector array This can be done either from the measured positions of lines with known wavelengths or from the geometrical design of the instrument It is more accurate, however, to combine both kinds of information in a least-squares fitting method This paper presents techniques for several spectrograph geometries, including flat and convex-curved crystals in reflection mode, with both flat and cylindrical film Also treated is a less common case where the diffracting planes are inclined to the crystal surface Uses of the calibration equations in wavelength determinations, resolution studies, and intensity measurements are discussed
TL;DR: In this article, the charge-coupled device (CCD) photoarray was characterized for rapid-scan spectroscopy and shown to produce signal linear with both intensity and integration time.
Abstract: Recently there has been a great deal of interest in the use of solid-state multichannel detectors as sensors for rapid-scan spectroscopy. The charge-coupled device (CCD) photoarray, not previously characterized for this application, is described. The unit has 1728 elements, arranged linearily, which integrate light over the same time frame; the photo signals are then read serially. The CCD was found to produce signals which are linear with both intensity and integration time. The dark signal at −10°C is 0.1% of saturation for a 10 ms integration time, and the noise level is less than 0.08% of saturation. The wavelength response is in the visible region. The application for rapid-scan spectrophotometry is also discussed.
TL;DR: In this paper, a series of copper chromite catalysts have been studied by x-ray photoelectron spectroscopy, and the data indicate that in the as-received form the copper is present as a mixture of Cu(OH)2 and CuO.
Abstract: A series of copper chromite catalysts have been studied by x-ray photoelectron spectroscopy. The data indicate that in the as-received form the copper is present as a mixture of Cu(OH)2 and CuO. After calcination at 500°C only CuO is present. The chromium is present as Cr+3 and Cr+6 when no promoter is added. When a BaO promoter is added, the Cr+6 is stabilized. Calcination at 500°C for varying periods of time alter the relative amounts of Cr+3 and Cr+6 on the catalytic surface. In addition, the relative amounts of the various oxidation states are a function of calcination temperature. At a calcination temperature of 240°C a Cr+5 surface species is reproducibly observed in one of the catalysts.