Showing papers in "Applied Spectroscopy in 1978"
TL;DR: In this article, an inductively coupled plasma sustained in flowing argon and a permanently aligned all-glass coaxial pneumatic nebulizer are employed in the atomic emission mode with a direct-reading polychromator for simultaneous multielement determinations.
Abstract: An inductively coupled plasma sustained in flowing argon and a permanently aligned all-glass coaxial pneumatic nebulizer are employed in the atomic emission mode with a direct-reading polychromator for simultaneous multielement determinations. The inductively coupled plasma is shown to be remarkably free from matrix and interelement effects by application for the determination of major (Na, K, P, Ca, and Mg) and trace (Fe, Cu, Zn, Mn, Pb, Cd, Co, Cr, Ni, V, Ti, Al, Sr, and Ba) elements in reference biologic materials and soil extracts. Wet-digestion and several dryashing sample preparation procedures are evaluated. Accuracy, precision, and sensitivity compare favorably with other multielement instrumental techniques (neutron activation analysis) energy dispersive x-ray fluorescence, solution-rotating disk atomic emission spectrometry) and with flame atomic absorption spectrometry. The directness of the method reported here is illustrated by use of one set of system operating conditions with one set of synthetic reference solutions used to establish a single calibration curve for each element.
358 citations
TL;DR: In this article, the Raman spectra of FeO, Fe3O4, α-Fe2O3, α -FeOOH, and γ-FeOH, the common products of iron oxidation have been measured.
Abstract: Raman spectra of FeO, Fe3O4, α-Fe2O3, α-FeOOH, and γ-FeOOH, the common products of iron oxidation, have been measured. The spectra of FeO and Fe3O4 appear to be identical. Armco iron oxidized in air at 250°C was examined by Raman spectroscopy after varying periods of exposure and the surface film was found to contain Fe3O4 and α-Fe2O3.
286 citations
TL;DR: Optical calculi for anisotropic media are reviewed and extended for use in a phase-modulation spectrophotometer as discussed by the authors, and it is demonstrated under which conditions signals proportional to linear and circular dichroisms may be collected, and artifacts may be introduced from either the optical systems or the medium itself.
Abstract: Optical calculi for anisotropic media are reviewed and extended for use in a phase-modulation spectrophotometer. It is demonstrated under which conditions signals proportional to linear and circular dichroisms may be collected, and how artifacts may be introduced from either the optical systems or the medium itself. Finally, conversions among the optical calculi in use are tabulated and discussed.
131 citations
TL;DR: In this article, Isett and Perez-Albuerne described the charge transfer complex of the TTT2I3, which was shown to have a conductivity of 1000 Ω−1 cm−1 at room temperature.
Abstract: The organic conductor bis(tetrathiotetracene)triiodide, (TTT)2I3, was prepared by Isett and Perez-Albuerne. The composition of the charge-transfer complex is shown in Scheme 1. This material was shown to be among the best of presently known organic conductors with a conductivity of 1000 Ω−1 cm−1 at room temperature. In order to study the iodide structure in this novel
75 citations
TL;DR: In this paper, a Fourier transform infrared system for real-time liquid chromatographic detection is described, where simple flowcell detection with automatic solvent subtraction is used, and detection of 500 ng of injected paraffin oil is demonstrated.
Abstract: A practical Fourier transform infrared system for real-time liquid chromatographic detection is described. Simple flowcell detection with automatic solvent subtraction is used, and detection of 500 ng of injected paraffin oil is demonstrated. Results from several chromatographic runs illustrate the system capability to serve as a real time infrared detector and simultaneously acquire infrared spectra.
61 citations
TL;DR: In this paper, the suppression of atomic excitation in a microwave-induced plasma due to the presence of sodium has been studied for three different nebulization systems and the results indicate that the sodium suppression effects observed can be largely accounted for by reductions in the analyte transport efficiency due to changes in the aerodynamic characteristics of the aerosol resulting from variations in the salt content of the nebulized solutions.
Abstract: The suppression of atomic excitation in a microwave-induced plasma due to the presence of sodium has been studied for three different nebulization systems. Evaluation of the factors affecting this effect has shown that its occurrence depends on the nature of the analytical aerosol introduced and the aerodynamic features of the sample nebulization system. The results indicate that the sodium suppression effects observed can be largely accounted for by reductions in the analyte transport efficiency due to changes in the aerodynamic characteristics of the aerosol resulting from variations in the salt content of the nebulized solutions. It is further shown that these effects may be generally predicted on the basis of fluid mechanical principles and that these may be used to design systems to eliminate the interferences. The study under-scores the essentiality of considering aerodynamic factors in formulating mechanistic explanations for interference effects in flames and plasmas.
58 citations
TL;DR: In this paper, the effects of three critical ICP operating parameters on atomic and ionic emission of elements of interest were investigated in detail, and the line/background ratios for both atom and ion lines were found to be very sensitive to (1) the aerosol Ar flow rate, (2) the observation height, and (3) the power and optimum conditions for ion lines are often quite different from those for atom lines.
Abstract: As a first step in the establishment of compromise conditions for multielement analysis by inductively coupled plasma (ICP) emission spectrometry, the effects of three critical ICP operating parameters on atomic and ionic emission of elements of interest were investigated in detail. The line/background ratios for both atom and ion lines were found to be very sensitive to (1) the aerosol Ar flow rate, (2) the observation height, and (3) the power, and optimum conditions for ion lines were often quite different from those for atom lines. In addition to assisting in the eventual choice of compromise ICP operating conditions for simultaneous multielement analysis, the results emphasize the importance of precise control of these critical parameters in analytical applications of the ICP.
57 citations
TL;DR: The application of inductively coupled plasma optical emission spectrometry (ICP-OES) to the elemental analysis of organic compounds is evaluated successfully for seven nonmetallic elements as discussed by the authors.
Abstract: The application of inductively coupled plasma optical emission spectrometry (ICP-OES) to the elemental analysis of organic compounds is evaluated successfully for seven nonmetallic elements. A comparison of this method with previously reported microwave techniques shows that, while both methods are sensitive (detection limits in the low nanogram region), ICP-OES has fewer complications and appears to be less prone to interferences than the analogous microwave techniques. The results of these studies suggest that ICP-OES should be applicable to the simultaneous multielement analysis of the gaseous effluents from a gas chromatograph.
50 citations
TL;DR: A number of simple products, containing the thioamide functional groups, have been investigated in infrared and Raman spectra; from the average appearance and potential energy distribution values, a pattern characteristic for the thiaamide groups has been given.
Abstract: A number of simple products, containing the thioamide functional groups, have been investigated in infrared and Raman spectra; from the average appearance and potential energy distribution values, a pattern characteristic for the thioamide groups has been given.
45 citations
TL;DR: In this article, a reaction system and a high temperature cell have been developed for the infrared spectroscopy of surface species during catalytic reaction, which was a closed circulation apparatus operated by a bellows pump, and the temperature of the cell could be varied over a wide range from −195 to 700°C.
Abstract: A reaction system and a high temperature cell have been developed for the infrared spectroscopy of surface species during catalytic reaction. The reaction system was a closed circulation apparatus operated by a bellows pump, and the temperature of catalyst in the cell could be varied over a wide range from –195 to 700°C. Thus, formate ion was detected on an alumina catalyst during the water gas shift reaction between 300 and 500°C. Also, the combination of the infrared spectroscopy with the temperature-programed desorption of adsorbed species made it possible to measure the amount of the formate ion on the catalyst.
43 citations
TL;DR: In this paper, the infrared and laser Raman spectra of vinylsilanetriol and vinylsilane coupling agents in H2O and D2O, respectively, are reported.
Abstract: Infrared and laser Raman spectra of vinylsilanetriol and vinylsilanetriol-d3 in H2O and D2O, respectively, are reported. Complete band assignments of the silanetriol group are discussed. In addition, band assignments of the vinyl group are reexamined. Most of the related bands to silanol are very broad or weak in intensity except for the SiO stretching modes which are potentially of use for structural analysis of silane coupling agents in the presence of glass surfaces.
TL;DR: In this article, the 3.39 μm He-Ne laser line was used to measure the absorption properties of C2 and higher hydrocarbons, and it was shown that the higher hydrocarbon absorptions include quite large numbers of absorbing states.
Abstract: Absorptivity measurements for the 3.39 μm He-Ne laser line are reported for methane, acetylene, ethylene, ethane, propane, n-butane, and n-pentane over the temperature range 300 < T < 2000°K. Shock-heated mixtures containing formaldehyde and methyl iodide showed no absorption or transient absorption at any temperature that could be attributed to formaldehyde or methyl radicals. The temperature dependence of the absorptivities of the C2 and higher hydrocarbons was much weaker than for methane. Comparison with simple theoretical expectations and broad-band absorptivities showed that the higher hydrocarbon absorptions include quite large numbers of absorbing states.
TL;DR: In this article, the analytical capabilities of a dc plasma used in combination with an echelle spectrometer have been evaluated, and the results show that they are equivalent or superior to those characteristic of flame atomic absorption and often competitive with those obtained with the inductively coupled plasma, atomic emission system.
Abstract: The analytical capabilities of a dc plasma used in combination with an echelle spectrometer have been evaluated. Measurements of the spectrometer resolution capabilities have demonstrated that they closely approximate the high values theoretically predicted but are ultimately limited by Doppler broadening effects occurring in the plasma. Investigations of possible ionization interference effects have shown that enhancements due to the addition of easily ionized elements are generally observed for elements having ionization potentials below approximately 8.5 eV; these may be compensated for by the addition of an excess of an easily ionized element. Evaluation of solute vaporization interference effects indicates that they also occur but can be negated by proper choice of operational conditions and/or the addition of releasing agents. Comparison of the detection capabilities of the system with those reported for other techniques shows that they are equivalent or superior to those characteristic of flame atomic absorption and often competitive with those obtained with the inductively coupled plasma, atomic emission system.
TL;DR: In this paper, an analysis of individual urban airborne particulates was conducted in the Raman microprobe, where spectral features characteristic of the particle were observed, and two features at ~1350 and ~1600 cm−1 were found to vary a function of the laser irradiance.
Abstract: Analyses of individual urban airborne particulates were conducted in the Raman microprobe. In addition to the spectral features characteristic of the particle, two features at ~1350 and ~1600 cm−1 have been observed. The appearance of these bands is found to vary a function of the laser irradiance. By modeling experiments, it is demonstrated that these two bands can be explained by the presence of carbon in a form analogous to polycrystalline graphite. In air particulates the source of the carbon can be either
TL;DR: In this article, positive ion mass spectra obtained by conventional electron impact and by methane chemical ionization were compared with the negative ion mass spectrum of 16 typical organophosphorus pesticides using methane, a methane-oxygen mixture, and oxygen as enhancement/reagent gases.
Abstract: Positive ion mass spectra obtained by conventional electron impact and by methane chemical ionization were compared with the negative ion mass spectra of 16 typical organophosphorus pesticides using methane, a methane-oxygen mixture, and oxygen as enhancement/reagent gases. In the negative ion spectra, phosphate and phenate anions typically carry a large fraction of the ion current. Displacement of chlorine by oxygen is noted in some cases, and migration of aryl groups from oxygen to sulfur is occasionally noted. Ion-molecule reactions between two species derived from sample molecules have been observed. The sensitivity of the negative ion techniques for the pesticides examined is greater than conventional electron impact or methane positive chemical ionization techniques, and can be up to 800 times more sensitive for some compounds.
TL;DR: In this paper, a method is described to remove interference fringes from infrared spectra by a computer-assisted spectral subtraction technique, which does not involve degradation of spectral quality in regions of low absorption.
Abstract: A method is described to remove interference fringes from infrared spectra by a computer-assisted spectral subtraction technique. The method does not involve degradation of spectral quality in regions of low absorption.
TL;DR: Reflection-absorption infrared spectroscopy is a technique for obtaining infrared spectra of thin films formed on the surfaces of plane metallic mirrors by reflecting infrared radiation from the mirrors at large, nearly grazing angles of incidence as discussed by the authors.
Abstract: Reflection-absorption infrared spectroscopy is a technique for obtaining infrared spectra of thin films formed on the surfaces of plane metallic mirrors by reflecting infrared radiation from the mirrors at large, nearly grazing angles of incidence Such spectra can, of course, provide a great deal of information about surface processes but for their correct interpretation it is essential to determine any differences in appearance between reflection-absorption spectra and transmission spectra that are inherent in the reflection-absorption technique
TL;DR: In this paper, the infrared spectra of aluminum chloride and aluminum hydroxide chloride solute species were determined using a Fourier transform infrared spectrometer, and significant differences in the IR spectra were observed.
Abstract: Infrared spectra of aluminum chloride and aluminum hydroxide chloride solute species were determined using a Fourier transform infrared spectrometer. The solutions which were examined contained: aluminum chloride; an aluminum hydroxide chloride with an OH/Al ratio of 2.4, prepared by dissolving freshly prepared aluminum hydroxide gel in an aluminum chloride solution; and an aluminum hydroxide chloride with an OH/Al ratio of 2.5, prepared by reacting aluminum metal with an AlCl3 solution. Significant differences in the infrared spectra were observed. All solute spectra contained bands in the 2500 to 3100 cm−1 region for the stretch of water coordinated to aluminum, with the bands for aluminum chloride solutions most intense. In the bending region for Al—O—H, bands were observed at 970 to 1080 cm−1. The polymeric solute species also had absorption bands, although at different frequencies, in the OH stretch region, 3300 to 3700 cm−1, and in the frequency region from 600 to 800 cm−1.
TL;DR: In this article, a nebulizer suitable for solutions with high percentages of dissolved solids and/or suspended solids was proposed, which is not ideal for ICP analysis.
Abstract: Inductively coupled plasma (ICP) sources have provided the analytical spectroscopist with a relatively simple means of performing quantitative analyses at very low concentration levels. Pneumatic solution nebulizers employed with ICP systems are a frequent source of problems. Presently available nebulizers demand that sample solutions contain a low percentage of dissolved solids and that there be no suspended solids which may cause flow restrictions or blockage. Many times, samples having one or both of these limitations require analysis. Although the samples themselves are not ideal for ICP analysis the concentration levels sought make this analytical method attractive, and an effort to find a nebulizer suitable for solutions with high percentages of dissolved solids and/or suspended solids was begun.
TL;DR: In this paper, a digital peak reader, providing both the peak height and the peak area from the same transient absorbance signal, has been built and tested for direct atomization of lead from a stainless steel wire, and two methods of measuring absorbance signals were compared.
Abstract: A digital peak reader, providing both the peak height and the peak area from the same transient absorbance signal, has been built and tested. The general performance including drift-compensating capability is reported. Three degrees of signal damping can be selected and the influence of these on the shape of analytical curves is illustrated for cadmium. The peak reader was applied to direct atomization of lead from a stainless steel wire, and the two methods of measuring absorbance signals were compared. Using the integrated absorbance values, the useful range of the calibration curve as well as the precision of the measurements were materially improved.
TL;DR: In this paper, the relative intensities of the 1048, 1067 A argon resonance doublet are reversed in favor of the 1.5 A line, although the Ar+ resonance lines are substantially increased relative to the neutral atom emissions.
Abstract: Windowless argon discharge tubes used as resonance lamps in matrix isolation experiments produced strong argon resonance radiation at 1048 and 1067 A, and at low pressures, the Ar+ resonance doublet at 920 and 932 A made a major contribution to the vacuum ultraviolet spectrum. At discharge pressures below 60 μ, the relative intensities of the 1048, 1067 A argon resonance doublet are reversed in favor of the 1067 A line, although the Ar+ resonance lines are substantially increased relative to the neutral atom emissions.
TL;DR: In this paper, the Fourier transform infrared spectra (3800 to 450 cm−1) and laser Raman spectra of crystalline phenylsilanetriol and phenyl-methyl-silanediol and triphenyl-silanol were used to aid the band assignment.
Abstract: Fourier transform infrared spectra (3800 to 450 cm−1) and laser Raman spectra (4000 to 0 cm−1) of crystalline phenylsilanetriol and phenylsilanetriol-d3, and liquid state phenylsilanetriol and phenylsilanetriol-d3 are first reported. Complete band assignments are attempted. All vibrational modes of the SiOH group except for the SiC torsional mode, including the SiOH in-plane and out-of-plane bending modes, are observed. In addition to the phenylsilanetriols, infrared and laser Raman spectra of crystalline diphenylsilanediol and triphenylsilanol are also studied to aid the band assignments.
TL;DR: Infrared spectroscopy has been of limited usefulness in the study of complex biological systems for some or all of the following reasons: 1.
Abstract: Infrared spectroscopy has been of limited usefulness in the study of complex biological systems for some or all of the following reasons: 1. Biological systems are generally dilute aqueous solutions. Thus, spectra of biological systems were run either in H2O (or D2O) with a resulting loss of large areas of the spectra because of the strong H2O (D2O) absorptions, or the spectra were run after removal of the water, which usually brings about major changes in the biological system. The use of thin cells to minimize the H2O or D2O absorption is not possible because "real-life" biological systems generally have a low solute concentration. The use of D2O posed additional problems because of hydrogen-deuterium exchange. 2. Biological systems generally contain many different species of proteins and, in such protein mixtures, variations in individual proteins or conformation changes can be difficult to identify by infrared spectroscopy especially when the changes only represent a small portion of the proteins. Thus, many infrared studies were of model systems containing a single protein species. 3. Biological systems contain numerous other organic species (besides proteins) which can have interfering infrared bands.
TL;DR: In this article, the adsorption and binding of uranium was studied by infrared spectroscopy and it was shown that uranium is retained as UO22+ by carboxylate groups which act as bidentate ligands.
Abstract: Brown coal removes uranium from sea water where it is present mainly as [UO2(CO3)3]4−. The adsorption and binding of uranium is studied by infrared spectroscopy. The spectra of the coal-uranium adducts still exhibit the asymmetric stretching vibration of the uranyl ion, but no CO32− frequencies, suggesting that uranium is retained as UO22+. The coal humic acids are shown to be responsible for the decomposition of the carbonato complex. The subsequent uptake of uranium is not a pure cation exchange process since the shift of the asymmetric uranyl stretching frequency from 950 cm−1 (hydrated UO22+) to 890 cm−1 points to complexation of UO22+ by carboxylate groups which act as bidentate ligands.
TL;DR: In this article, a novel technique is introduced for the measurement of rise velocities of hot, laminar flames, where tiny individual droplets of a solution containing alkali or alkaline earth elements are repetitively introduced into the flame to be examined.
Abstract: A novel technique is introduced for the measurement of rise velocities of hot, laminar flames. The new technique is straightforward to implement, rapid to employ, and more accurate than previous methods based on the observation of moving heated particles. In the method, tiny individual droplets of a solution containing alkali or alkaline earth elements are repetitively introduced into the flame to be examined. The small cloud of atomic vapor which is produced upon atomization of a droplet is then monitored photo-metrically as it passes two well-defined points in the flame. Knowledge of the distance between the points and measurement of the time required for the atoms to traverse it thus enables the flame velocity to be calculated. Conveniently, velocity measurements with this technique are localized in the flame, thereby permitting spatial variations in flame velocity to be examined. Moreover, the negligible mass of the moving, measured atom cloud eliminates error otherwise caused by gravitational attraction and its decelerating effect. The utility of this new technique is demonstrated through the measurement of localized velocities in a laminar, air-acetylene flame.
TL;DR: In this article, the rotational lines of a molecular N2+ band system were used to evaluate the temperature of the tail flame at various heights above the load coil, ranging from approximately 8000°K at 17 mm above the coil to 6400 at 41 mm.
Abstract: In recent experiments with a 9.2 MHz inductively coupled plasma assembly air was used as cooling gas. The molecular N2+ band system appeared on the photographic plates taken in the first order of a 3.4 m Jarrell-Ash Ebert grating spectrograph. The rotational lines of this band system was used to evaluate the temperature of the plasma tail flame at various heights above the load coil. These varied from approximately 8000°K at 17 mm above the coil to 6400 at 41 mm.
TL;DR: In this article, the feasibility of resonance Raman spectroscopy in the detection of hazardous chemicals in water has been tested on some nitrophenol-based pesticides and fungicides.
Abstract: The feasibility of resonance Raman spectroscopy in the detection of hazardous chemicals in water has been tested on some nitrophenol-based pesticides and fungicides. In most cases, detection limits below the parts per million level were obtained. The method was also tested on an artifically polluted river water sample.
TL;DR: In this paper, a small volume, self-contained, anaerobic circulating flow cell was developed and applied to the resonance Raman investigation of two heme proteins: carboxyhemoglobin and cytochrome c. The cell was demonstrated to be effective in reducing photodissociation of light-sensitive compounds.
Abstract: A small volume, self-contained, anaerobic circulating flow cell has been developed and applied to the resonance Raman investigation of two heme proteins: carboxyhemoglobin and cytochrome c. The cell has been demonstrated to be effective in reducing photodissociation of light-sensitive compounds. The flow performance is competitive with several alternative approaches. Electrochemical methods have been coupled with visible absorption and resonance Raman spectroscopy to titrate and determine potentiometrically the formal reduction potential of cytochrome c. Agreement between the results of visible and Raman spectral data demonstrates the feasibility of utilizing quantitative resonance Raman spectroscopy as a probe of formal reduction potentials of enzyme components.
TL;DR: In this article, X-ray photoelectron spectroscopy has been used to identify and determine the oxidation states of a number of major and minor elements present on the surface of fly ash particles.
Abstract: X-ray photoelectron spectroscopy has been used to identify and determine the oxidation states of a number of major and minor elements present on the surface of fly ash particles. With the use of a sputtering-etching procedure, relative concentrations as a function of depth were obtained for Si, Al, Fe, Ca, Na, C, O, and S. The concentrations of Na, C, O, and S were found to decrease and Si, Al, and Fe were found to increase upon sputtering to a depth of approximately 50 A.
TL;DR: In this paper, the utility of infrared emission spectroscopy as applied to the study of the oxidation of metal surfaces was pointed out, and it was shown that good results can be achieved even with standard dispersion spectrophotometers.
Abstract: The present work points out the utility of infrared emission spectroscopy as applied to the study of the oxidation of metal surfaces. It is shown that good results can be achieved even with standard dispersion spectrophotometers. The work shows emission spectra obtained at a temperature of only 133°C from samples of about 380 A thickness and 2 cm2 area. The molybdenum oxides are particularly useful to test the capability of the infrared emission spectroscopy technique. The study of the behavior of the emission bands and the differences between the emission and absorption spectra show that this technique cannot only be an alternative to absorption spectroscopy, but also can give different data from those which can be achieved by the absorption technique. Spectra are recorded directly on the oxidizing sample. The increase in intensity and the change in the shape of the bands are monitored while the oxidation is performed. It is noted that with infrared emission spectroscopy, sample preparation is greatly simplified.