bluuebunny/crossref_metadata_2025 huggingface dataset:
Materials Characterization Using Factor Analysis of FT-IR Spectra. Part 1: Results
Authors: Fredericks Peter M. , Lee James B. , Osborn Paul R. , Swinkels Dom A. J.
Published: June 2005

A method is presented which allows the FT-IR spectrum of a material to be related to many of the significant practical properties of that material. The method uses factor analysis of all or part of the spectra of a calibration set of well-characterized samples to determine the minimum set of factors and the associated factor loadings required to reproduce the spectra. Multiple linear regression of the factor loadings against measured properties gives close correlations which are used to predict the properties of unknown samples similar to those constituting the base set. The method is often fast compared with conventional techniques and, by suitable choice, of calibration sets, can give semiquantitative results for a widely varying set of samples, or quantitative results of accuracy comparable with conventional techniques for a calibration set and unknowns from a narrower range of samples. Examples of the use of the method are given for coal, bauxite, manganese dioxide ore, and diesel fuel.
Materials Characterization Using Factor Analysis of FT-IR Spectra. Part 2: Mathematical and Statistical Considerations
Authors: Fredericks Peter M. , Lee James B. , Osborn Paul R. , Swinkels Dom A. J.
Published: June 2005

A method is described whereby the wealth of information present in the Fourier transform infrared spectrum of a material may be extracted and used to estimate useful properties of the material. Factor analysis is used to condense the data, after which the use of multiple linear regression allows correlations to be established for a calibration set, from which properties of unknown samples can be estimated.
Infrared Reflection-Absorption Studies of Thin Films at Grazing Incidence
Authors: Rabolt J. F. , Jurich M. , Swalen J. D.
Published: June 2005

Infrared spectra of thin films (<200 Å) on metals have been observed with Fourier Transform IR spectroscopy (FT-IR) by improvements to the grazing incidence reflection methods proposed by Greenler. Theoretical extensions to the reflectivity ratio, ( R – R0) /R0 for a number of metals have been made and indicate the optimal conditions for each experiment. Grazing incidence reflection measurements of poly(methyl methacrylate) (PMMA) films (thickness 180 Å) have been made on silver-, aluminum-, copper-, and chromium-coated substrates. Although the reflectivity ratio maximizes at an angle which deviates a few degrees from pure grazing, filling factor considerations and optimal optical fields show both experimentally and theoretically that operating some ten degrees away from grazing gives better signal-to-noise spectra for reasonable accumulation times. Furthermore, a shift in the maximum of the reflectivity ratio curve is observed from one metal to another, and a comparison between silver and chromium is used to illustrate this effect on the observed IR spectra.
An Optimization of Detector-Noise-Limited Infrared Multiwavelength Determinations
Authors: Honigs D. E. , Hieftje G. M. , Hirschfeld T.
Published: June 2005

The existence of optimal absorbance levels for absorption spectrophotometry is well known. The corresponding phenomenon in the multiwavelength measurements characteristic of correlation spectroscopy lends itself to a similar analysis. The resulting optimization equation is quite complex, but can be approximated for several simplified cases. For very similar absorbances among the set of used wavelengths, or for a situation where the absorbance multiplied by its weighting factor at a given wavelength is far greater than for all the others, the classical optimum at A = 0.434 still applies. For a uniform distribution of absorbance, the optimal maximum absorption is A = 0.868. The complex general case can be rearranged to calculate, given data at a given pathlength, what the optimum pathlength should be. In multiwavelength determinations, the optimal condition involves equal relative error in the largest and the smallest absorbance.
The Widespread Applicability of Lognormal Curves for the Description of Absorption Spectra
Authors: Metzler Carol M. , Cahill Allen E. , Petty Sue , Metzler David E. , Láng L.
Published: June 2005

We have fitted over 160 electronic absorption spectra of over 95 aromatic compounds and some other substances with lognormal distribution curves to evaluate the shapes of the bands. The compounds include simple benzene derivatives, phenols, anilines, benzaldehyde, benzoic acid, nitrobenzene, and potassium permanganate. The well-defined n-π* transitions of acetone, benzaldehyde, nitrobenzene, and pyrazine are included. Effects of solvents have been studied in a number of cases. The fitting of absorption bands with lognormal curves is compared with resolution with Gaussian curves or with other types of skewed Gaussian curves. We conclude that the lognormal curve provides an excellent approximation to the shapes of spectral bands in aromatic as well as many other organic and inorganic compounds. The ability to analyze complex spectra by resolution with lognormal curves may be usefully applied in a number of ways.
Atomic Absorption Determination of Titanium and Vanadium in Uranium Concentrates
Authors: Batistoni Daniel A. , Smichowski Patricia N.
Published: June 2005

An atomic absorption procedure was developed for the determination of titanium and vanadium in medium-purity uranium products (yellow-cakes). Samples equivalent to 4 g uranium were dissolved in 5.5 M nitric acid. Titanium and vanadium were separated from the uranium matrix by column extraction chromatography with the use of tri- n-butyl phosphate (TBP) supported on polytrifiuorochloroetylene (Kel-F)® powder. A nitrous oxide-acetylene flame was employed to estimate the concentration of the analytes in the nitric phase. The precision was about 3% relative standard deviation for both elements, with detection limits of 60 μ/g for Ti and 30 μg/g for V. The influence of AI, Fe, and PO43−on the measured absorbance values and mutual interferences effects between Ti and V were investigated.
Fluorescence Lifetime and Oxygen Quenching Rate of Gas-Phase Fluoranthene Excited at 337.1 nm
Authors: Jandris Louis J. , Forcé R. Ken , Yang Sze Cheng
Published: June 2005

We report that the fluorescence lifetime is 38 ± 2 ns and that the oxygen quenching rate constant is 2.49 × 109 L mol−1·s−1 for gas-phase fluoranthene excited at 337.1 nm. A fluorescence lifetime of 24 ± 3 ns for excitation at 351 nm has been reported previously by Ehrlich and Wilson [J. Chem. Phys. 67,5391 (1977)]. According to the current spectroscopic assignments, the 337.1-nm and the 351-nm lasers excite fluoranthene molecules to the same S2 electronic state with excess vibrational energies of 1900 cm−1 and 710 cm−1, respectively. Therefore, our measured lifetime reveals an anomalous trend of the fluorescence lifetime if both the current spectroscopic assignment and the value of 24 ns for the lifetime excited at 351 nm are accepted. Our measured oxygen quenching rate constant indicates that the oxygen quenching rate for fluoranthene is about 100 times slower than that of anthracene and pyrene. The unusually slow oxygen quenching rate in the gas phase may be related to the previously reported unusual inertness of excited fluoranthene molecules in other environments. Possible explanations of these abnormal behaviors of fluoranthene are discussed.
Inelastic Electron Tunneling Spectroscopy of Hydridotriosmium Decacarbonyl Adsorbed on an Alumina Surface
Authors: Hilliard Lisa J. , Gold Harvey S.
Published: June 2005

Inelastic electron tunneling spectroscopy (IETS) was utilized to study hydridotriosmium decacarbonyl supported on an activated alumina surface. Triosmium dodecacarbonyl was adsorbed under a variety of conditions to give a surface-linked species. The bridging hydrogen observed at 1509 cm is in accord with previous observations. Use of IETS to study supported metal cluster catalysts is critical to the rational design of novel catalysts.
Formaldehyde Detection in Air by Laser-Induced Fluorescence
Authors: Möhlmann G. R.
Published: June 2005

A method is described for the instantaneous concentration measurement of formaldehyde (H2CO) in air by laser-induced fluorescence of the H2CO (Ã1A″-X˜1A1) electronic transition. Concentrations down to about 13 ng/litre (about 10 ppb) can be determined in about 100 seconds without any sample collection, water extraction, or further chemical treatment. The influence of the presence of water vapor and methanol vapor in the air on the accuracy of the method has been investigated. It appeared that if the humidity of the ambient air is not taken into account, the detection limit is about 0.15 ppm H2CO in air; the presence of methanol has no influence on the accuracy.
Optimization Approaches to the Determination of Arsenic and Selenium by Hydride Generation and ICP-AES
Authors: Parker Lloyd R. , Tioh N. H. , Barnes Ramon M.
Published: June 2005

Simplex optimization, factorial design, regression analysis, and canonical analysis are applied to the determination of arsenic and selenium by hydride generation with inductively coupled plasma atomic emission spectrometry. For each element, four factors governing the operation of the plasma (outer, intermediate, and carrier gas flow rates, and rf power) and two chemical factors governing the hydride generation (quantity of acid and of sodium borohydride) were optimized by the simplex algorithm. A mapping study was conducted for the two chemical factors which consisted of a factorial design followed by regression analysis and canonical analysis. The results provided precise locations of the optima and gave information regarding the effects of the two factors.
Identification of Limiting Noise Sources in the Microwave-Induced Nitrogen Discharge at Atmospheric Pressure
Authors: Deutsch R. D. , Hieftje G. M.
Published: June 2005

The noise from the emission signal of the microwave-induced nitrogen discharge at atmospheric pressure (MINDAP) has been analyzed. Wavelength-scan flicker-ratio, precision measurements, time-trace correlation and noise amplitude spectra were used to determine the individual components of the system noise. Noise spectra are reported with the use of a nebulizer sample introduction system for desolvated and undesolvated aerosol, for varying analyte concentration, and for background emission from nitrogen and water vapor. The analytical system appears to be flicker-noise-limited below about 1 Hz for all measurements made. Only 60 and 120 Hz peaks are detected in the frequency region extending to 700 Hz, and presumably arise from the microwave power supply
Laser Raman Spectroscopy of Tungsten-Halogen Bulbs
Authors: Sell J. A. , Eesley G. L. , Simon D. L.
Published: June 2005

Laser Raman spectroscopy is used to nondestructively measure molecular species that are found in tungsten-halogen bulbs. In particular, reactions are studied in an experimental bulb filled with CBrF3 in Kr. It was found that CBrF3 decomposes after ∼10 seconds of accumulated burn time of the filament, and that Br2 forms and then decomposes. An unusually large Br2 signal was found to result from resonance fluorescence, as well as possible resonance Raman scattering. In addition, it was found that the compounds HBr, CO, and SiF4 formed and persisted in the bulb. Raman spectroscopy was also used to identify a solid deposit on the inside surface of the glass envelope as WO3(s). Finally, the total pressure of the bulb was measured nondestructively by Rayleigh scattering.
“Top-Down” versus “Side-On” Viewing of the Inductively Coupled Plasma
Authors: Faires Lynda M. , Bieniewski Thomas M. , Apel Charles T. , Niemczyk Thomas M.
Published: June 2005

The inductively coupled plasma is viewed by a “top-down” optical configuration, and the analytical performance is compared to conventional “side-on” viewing in terms of sensitivity, detection limits, linear dynamic range, self-reversal effects, and multielement performance. This comparison is made for a selection of eleven atom and ion lines of eight elements. The results of this study indicate distinct advantages in “top-down” viewing including improved sensitivity, lower detection limits, better signal-to-background ratios, and better compromise viewing position for multielement analysis. An exception to these advantages is increased self-absorption effects observed for the alkali elements.
Molecular Density Measurements Using Tunable Semiconductor Lasers in a Supersonic Flow
Authors: Kim K. C. , Filip H.
Published: June 2005

Tunable semiconductor lasers were used to probe flow-cooled UF6 molecules in a supersonic nozzle expansion. The number density obtainable and condensation characteristics were determined.
Development of a Continuous-Flow Hydride and Mercury Vapor Generation Accessory for Atomic Absorption Spectrophotometry
Authors: Sturman B. T.
Published: June 2005

The design and performance characteristics of a continuous-flow vapor generation accessory for atomic absorption spectrophotometry are reported. When used with a conventional atomic absorption spectrophotometer, the accessory provides analytical sensitivity for mercury, arsenic, selenium, antimony, bismuth, tellurium, and tin equal or superior to that of a batch-type vapor generation device. Sample presentation, sample consumption, precision of measurement, and simplicity of operation are similar to those of flame atomic absorption with a pneumatic nebulizer. Details of the construction of the continuous-flow manifold, gas/liquid separator, and absorption cells are discussed, and the effects of reagent concentrations and carrier gas flow rates are shown. Characteristic concentrations and analytical curves for the above elements are also presented.
Hydrogen Isotope Analysis Using a Reduced-Pressure ICP Torch
Authors: Miller D. C. , Seliskar C. J. , Davidson T. M.
Published: June 2005

Despite the apparent nonequilibrium conditions found in the plasma, this research has demonstrated that the flowing, reduced-pressure inductively coupled argon plasma can provide a rapid, sensitive, and effective new analytical method for hydrogen isotope analysis. The important characteristics which make this method useful include the following: no apparent molecular emission, the ability to correct the apparent isotope effect observed in static systems by flow regulation, the linearity of the response of atomic hydrogen and deuterium line intensities with concentration of H2 and D2 injected in the plasma gas mixture, and the minimal memory effects.
A Microcomputer-Controlled Simultaneous Multielement Nondispersive Atomic Fluorescence Spectrometer
Authors: Naranjit D. A. , Radziuk B. H. , Rylaarsdam J. C. , Larkins P. L. , van Loon J. C.
Published: June 2005

An eight-channel multielement nondispersive AFS spectrometer based on the time division multiplex method and fitted with a Commodor PET 2001 microcomputer to control lamp firing and for data manipulation is described. The pulsed behavior of ten EDLs with respect to rf power, mode of pulsing, and step frequency is examined. This device is tested with the use of an air-acetylene flame atomizer. An in-depth examination of light scattering showed that such scattering depends on the particular analyte lamp, the angle of detection, and the sample matrix. Scatter correction in the analysis of NBS bovine liver, orchard leaves, fly ash, and river sediment was done with the use of a lamp of an element not present in the sample. Results are mixed, with good values being obtained for elements present in a sample matrix in which the analyte signal is appreciably greater than the scatter signal. Detection limits for ten elements in an air-acetylene flame are given for three different lamp duty cycles. The detection limits, generally, were comparable to those obtainable by ICP-AES, ICP-AFS, and flame AAS. Simultaneous multielemental analysis (up to eight elements) is possible with the proposed equipment.
Frequency Jitter from Mechanical Vibrations in a Diode Laser Mounted on a Closed-Cycle Refrigerator
Authors: Melandrone G. , Cappellani F. , Restelli G.
Published: June 2005

Frequency jitter in a tunable diode laser output due to impact shocks produced by the closed-cycle refrigerator has been characterized as a function of the piston movement during different phases of the cycle. An analysis of the influence of the vibration-induced noise suggests a random (Gaussian) contribution to the laser spectrometer lineshape.
An Instrument for Determining Single and Multiple Room-Temperature Phosphorescence Lifetimes
Authors: Nithipatikom K. , Pollard B. D.
Published: June 2005

A Room-Temperature Phosphorescence Lifetime Spectrometer (RTPLS) capable of resolving multicomponent intensity decays into separate lifetimes is described. Careful blank subtraction facilitated by a reproducible chopped-xenon arc source and data reduction with the use of nonlinear least-squares reconvolution are major features of the RTPLS. The performance and limitations of the RTPLS were evaluated with synthetic data and prepared samples. Better than 2% RSD was attained for multiple determinations of a single sample. 4-amino-1-naphthalenesulfonate, sodium salt and 2-naphthalenesulfonate, sodium salt both exhibit decays resolvable into two lifetimes when they are coadsorbed with NaI onto filter paper. The approximate ratio of the lifetimes is 1 to 10, and the shorter component is proposed to be a charge transfer complex between the analyte and NaI.
Ultramicrosampling in Infrared Spectroscopy Using Small Apertures
Authors: Curry C. J. , Whitehouse M. J. , Chalmers J. M.
Published: June 2005

A method for obtaining IR spectra from submicrogram quantities of polymeric materials, with minimum sample preparation, using small apertures, is described. Spectra were obtained for thin films and fibers with the use of three FT-IR instruments: a research-grade spectrometer and two low-cost “bench top” spectrometers. The quality of the spectra obtained are evaluated in terms of the instrument type, detector, accumulation times, and the dimensions of the aperture. A usable spectrum was obtained from as little as 2 ng of poly-(ethylene terephthalate) with the use of the research-grade instrument, which employed a cooled MCT detector. Spectra were readily obtained from the low-cost instrument with the use of a standard TGS detector from ∼500 ng of material and were of sufficient quality for identification purposes. It would seem that energy limitations, diffraction effects, and long accumulation times would limit the utilization of apertures of less than 10 microns in diameter.
Optical Fibers for Remote Spectrometry of Alkali Elements in the dc Arc
Authors: Faires Lynda M. , Bieniewski Thomas M. , Apel Charles T. , Niemczyk Thomas M.
Published: June 2005

An optical fiber cable is designed, characterized, and applied to the remote spectrometric analysis of alkali elements as impurities in plutonium by dc arc emission. The analytical performance of the dc arc/optical fiber/polychromator system is tested by the establishment of analytical working curves for sodium, potassium, and rubidium from a set of standards. Accuracy, determined by the use of control samples of known concentration, is found to be 10% or better. The new analytical system provides improvement in both accuracy and efficiency compared to the previously used spectrographic technique.
An Experimental Study of the Precision of Fluorescence Measurements
Authors: Almeida Manuel C. , Seitz Rudolf
Published: June 2005

The precision of fluorescence measurements by the SLM 22 fluorometer was calculated with the use of fluorescein solutions of varying concentrations. Relative standard deviations for 10 replicate fluorescence measurements, each integrated over five seconds, are not observably affected by the changing of bandpasses from 1 to 8 nm, by the changing of cell orientation, or by fluorescein concentration at levels of 1.0 × 10−9M and above. Fluctuations in source intensity are shown to be the primary source of noise. Statistical fluctuations in photon and photoelectron flux do not seem to be a significant source of variability. Because of this, the precision of single-channel intensity measurements is poorer than for intensity measurements ratioed directly to source intensity. However, the precisions of the ratio of fluorescence intensities measured by dual detectors on opposite sides of the cell were often found to be better than for intensity measurements ratioed to the source. It is hypothesized that this is observed because the measurements of source intensity and fluorescence are not identically affected by fluctuations in the source. At fluorescein concentrations in the 10−9M range and above, percent RSDs for single channel measurements typically fall in the range of 0.2% to 0.5%, although occasionally larger values are observed. The percent RSDs for the ratio of simultaneous fluorescence measurements are typically in the range of 0.1 to 0.2% at higher concentrations.
Pump/Probe Thermal Lens Spectroscopy with Polarization-Encoded Laser Beams
Authors: Pang Teng-Ke Joseph , Morris Michael D.
Published: June 2005

A new detection system for pump-and-probe thermal lens spectroscopy has been developed. Two orthogonally polarized beams derived from the same CW laser serve as pump and probe. The pump beam is chopped and recombined with the probe laser. A Glan prism located after the absorption cell separates pump-and-probe beams. The thermal lens is sensed as the probe beam overflows a limiting aperture and is processed through a lock-in amplifier. The thermal lens response is linear in analyte concentration. The system is applied to liquid chromatography detection. The noise level is about 4 microabsorbance rms. Once aligned, the system remains in alignment indefinitely, since laser pointing instabilities cancel.
Investigation of Water and Hydroxyl Groups Associated with Coal Fly Ash by Thermal Desorption and Fourier Transform Infrared Photoacoustic Spectroscopies
Authors: Seaverson L. M. , McClelland J. F. , Burnet G. , Anderegg J. W. , Iles M. K.
Published: June 2005

Thermal desorption spectrometry (TDS) and Fourier transform infrared photoacoustic spectroscopy (FT-IR/PAS) have been used in combination to analyze the water and hydroxyl groups associated with four coal fly ashes. Measurements using the former technique on these ashes resulted in identification of three water desorption regions in the temperature range from 25° to 1100°C. The regions consisted of a small desorption peak at 50°, a broad band from 180° to 400°, and an intense peak from 400° to 590°. No additional water desorption was observed up to 1100°. A fourth ash gave a similar spectrum except that it lacked the intense last peak. The TDS spectra together with FT-IR/PAS spectra taken on samples exposed to pre- and post-desorption peak temperatures allowed the first TDS peak to be assigned to the desorption of physically adsorbed water, the broad band to desorption of hydrogen-bonded surface hydroxyls, and the intense last peak to the decomposition of Ca(OH)2.
Direct Detection of Beryllium on Filters Using the Laser Spark
Authors: Cremers David A. , Radziemski Leon J.
Published: June 2005

A method has been developed to spectrochemically analyze beryllium particles on filters using the laser spark. The spark, formed on the filter by a cylindrical lens, is 0.1-mm wide and 4- to 8-mm long. By the rotation of the filter under the spark, a large area can be sampled in only a few minutes. The surface detection limit (SNR = 6) for particles 0.5–5 μm in diameter is 0.45 ng/cm2, which corresponds to 3.6 ng total Be mass on the exposed area (32-mm diam.) of a 37-mm-diam. filter. The RSD for replicate sample analysis is 4%. Several methods of calibrating the technique are discussed. The effects of particle size and some contaminants on the analysis are described. The usefulness of this method for monitoring airborne beryllium concentrations is considered.
On the Artifacts in Circularly Polarized Emission Spectroscopy
Authors: Shindo Yohji , Nakagawa Masayuki
Published: June 2005

Circularly polarized emission (CPE) is observed from achiral fluorescent molecules dissolved in optically inactive solvents. An extensive investigation is carried out to determine whether or not the signal observed is a true solvent-induced CPE signal. As a result, the following three decisive factors responsible for the origin of the artifact in CPE spectroscopy are presented: (1) the amount of linear polarization in emission; (2) the residual static birefringence of the optical system due mainly to an electro-optical modulator; and (3) the second harmonics response of the lock-in amplifier used in the electronic system.
Photochemical Dissociation in Optically Dense Solutions: Applications to Photolyzed Carboxymyoglobin (Mb*CO)
Authors: Fiamingo Frank G. , Alben James O.
Published: June 2005

Photodissociation of ligands has made important contributions to the understanding of function and structure of heme proteins. Here we present a theory for photochemical dissociation that is not limited by the assumption of previous analyses of optically thin samples, and apply it to interpretation of the photodissociated state of carboxymyoglobin (Mb*CO). Equations are derived and presented in terms of the effects of absorbance, [log10( I0/ I) = A, the probability of absorption of light quanta per unit surface area], and the potential for dissociation, D (maximum probability of photodissociation per unit surface area; a linear function in time of photolysis), for both monochromatic and polychromatic light sources. When monochromatic light is used, we show that for large absorbances ( A > 2) the fractional photolysis increases as (log D)/ A, and may appear to “saturate” even though well below completion. For polychromatic light intensities and absorbances, the theory predicts that the near-infrared tail of the absorbance band of carboxymyoglobin should be sufficiently transparent to allow the radiation to penetrate the sample, yet still have a significant absorptivity such that complete photodissociation is possible. An optically thick myoglobin-CO sample illuminated with a tungsten lamp was observed to behave somewhere between these two theories. These theoretical relations may be useful in the analysis of photolysis data from optically dense solutions and as a guide for future experimental design.
The ODD OVER EVEN Test for FT-IR Interferometers
Authors: Saperstein David D. , Golden William G.
Published: June 2005

Timing and intensity nonlinearities are highlighted with a new test for FT-IR instruments.
Trace Analysis and Speciation for Methylated Organotins by HPLC-Hydride Generation-Direct Current Plasma Emission Spectroscopy (HPLC-HY-DCP)
Authors: Krull Ira S. , Panaro Kenneth W.
Published: June 2005

Total tin determinations can be accomplished at trace levels (10–25 ppb) by a continuous on-line hydride generation (HY), followed by direct current plasma (DCP) emission spectroscopy (HY-DCP). This approach is applicable for organotin compounds such as mono-, di-, and trimethyltin chloride, as well as stannous and stannic cations. HY-DCP methods of total tin analysis have been applied to a number of spiked and actual samples. Detection limits, calibration plots, sensitivities, and related analytical parameters have been evaluated. Organotin analysis and speciation can be accomplished by the interfacing of this HY-DCP step with high-performance liquid chromatography (HPLC), with the use of a polymeric PRP-1 type column with an acidic, ionic mobile phase, usually containing a suitable ion-pairing reagent. The overall speciation approach, HPLC-HY-DCP, has been evaluated with regard to separation conditions; detection limits; sensitivities; calibration plots; and applications to spiked water, clam juice, seawater, and tuna fish samples. The results suggest the suitability and reliability of this HPLC-HY-DCP approach for individual tin species. Other metal species capable of forming a hydride derivative on-line, in a continuous fashion, may also be suitable for speciation by HPLC-HY-DCP.
Rapid Coal Analysis. Part II: Slurry Atomization DCP Emission Analysis of NBS Coal
Authors: McCurdy D. L. , Wichman M. D. , Fry R. C.
Published: June 2005

A McCrone Micronising Mill is used to wet grind NBS bituminous coal to a median particle diameter of 5.7 μm within 10 min. The finely divided coal slurry is immediately nebulized without sieving into a three-electrode DCP for accurate trace element determinations within 15 min overall elapsed time. Three important parameters contribute to near-quantitative elemental recovery without the use of wet or dry ashing, matrix matching, standard additions, or correction factors. These parameters are: (1) extremely small coal particle size, (2) spray chamber conditions favoring unusually efficient aerosal mass transport, and (3) high particle atomization efficiencies characteristic of the hot DCP. Near-unity response factors are observed for the rapid DCP emission determination of trace metals in finely divided coal slurry. Calibration may therefore be performed simply with aqueous standards. The slurry method gives near quantitative agreement between experimental and certified values for Cr, Cu, Mg, Mn, Ni, and Pb in NBS bituminous coal.
Rapid Coal Analysis. Part I: Particle Size Effects in Slurry Methods Based on Flame AA and Swing-Mill Grinding
Authors: Mohamed N. , McCurdy D. L. , Wichman M. D. , Fry R. C. , O'Reilly James E.
Published: June 2005

Laser diffraction particle size measurements are used to study aerodynamic mass transport losses of a finely ground aqueous coal slurry aerosol in the spray chamber of a conventional atomic absorption spectrometer. A swing mill used to grind the coal produces many particles small enough to transport efficiently in the aerosol stream, but some are too large and can settle out in the spray chamber. This effect is reduced but not eliminated if one passes the grindings through a 325-mesh sieve prior to weighing and direct analysis. In spite of the partial “leveling effect” produced by the sieve, the residual mass transport loss in the spray chamber for direct coal slurry analysis by flame AA is about 51% (relative to aqueous standard transport). This accounts for part of the five-fold decrease in absorbance previously reported for finely ground coal slurries as compared with aqueous solutions. The remainder of the decrease is due to incomplete combustion and vaporization of coal particles in the nitrous-oxide/acetylene flame.
The Fourier Self-Deconvolution of Raman Spectra
Authors: Bowley H. J. , Collin S. M. H. , Gerrard D. L. , James D. I. , Maddams W. F. , Tooke P. B. , Wyatt I. D.
Published: June 2005

Resolution enhancement by the use of Fourier self-deconvolution has been achieved with Raman spectra obtained from an instrument with an intensified diode array detector. A minimum signal-to-noise ratio of about 500:1 is acceptable and this is readily attainable, by spectral accumulation, in the case of relatively strong peaks such as those of carbon tetrachloride at 549 cm−1 and tetrahydrofuran at 915 cm−1. Resolution enhancement factors, K, of about 2.7 are then achieved. Weaker peaks, typified by the v (C-Cl) modes of polyvinyl chloride) require more extensive spectral accumulation, but a K value of 2.2 has proved feasible. The finite resolution imposed by the diode array detector is not a significant limitation. In order to obtain consistently good results it is necessary to optimize the signal-to-noise ratio, by choosing instrumental operating conditions best suited to specific samples.
The Effect of Integration Time and Interval on Precision with Three Pneumatic Nebulizers Used for Inductively Coupled Plasma Atomic Emission Spectrometry
Authors: McGeorge S. W. , Salin E. D.
Published: June 2005

The long-term behavior of three popular pneumatic nebulizers was observed and compared, with particular attention given to signal-to-noise ratio. Results indicate that sample changeover time and, consequently, spray-chamber clearing time, should be as short as possible. Precision varied widely for each nebulizer depending on the interval between data values. Integration times as short as 0.1 s can yield relative standard deviations of about 1%. Each of the nebulizers was capable of delivering better than 1% RSD, and two provided RSDs less than 0.4% under certain conditions. The implications of these measurements on instrument and experiment design are discussed.
Theory and Evaluation of a Windowless Nonresonant Optoacoustic Cell
Authors: Tilden Scott B. , Denton M. Bonner
Published: June 2005

A novel nonresonant flow-through optoacoustic cell is characterized. This cell is operated without windows, completely eliminating the window background interference. Data are presented comparing sensitivity, resistance to cross-contamination, and operating characteristics of this approach with more conventional single and differential cell techniques. The capability of operation at widely varying sample flow rates is demonstrated.
Kinetic Energy Distributions of Positive Ions in an Inductively Coupled Plasma Mass Spectrometer
Authors: Olivares José A. , Houk R. S.
Published: June 2005

A simple method is described for the approximate measurement of the ion energy distribution in an inductively coupled plasma-mass spectrometer (ICP-MS) with a continuum flow sampling interface. The average ion kinetic energy, kinetic energy spread, and maximum kinetic energy are evaluated from a plot of ion signal as a function of retarding voltage applied to the quadrupole mass analyzer. The effects of plasma operating parameters on ion signals and energies are described. In particular, kinetic energy is a sensitive function of aerosol gas flow rate. This behavior is attributed to a nonthermal, possibly electrical, interaction between the plasma and the sampling interface, which is induced by the presence of the axial channel in the ICP.
Temperature-Induced Molecular Reorganization in Thin Films and on Surfaces as Observed by Grazing Incidence Infrared Spectroscopy
Authors: Schlotter N. E. , Rabolt J. F.
Published: June 2005

With the use of a thermostated grazing incidence reflection (GIR) infrared cell, spectra of organic monolayers and thin polymer films have been obtained as a function of temperature. Results indicate that insight into the mechanism of molecular reorganization which often occurs at elevated temperatures can be obtained through thermal cycling experiments. In particular, studies of ultrathin poly(methylmethacrylate) [PMMA] films as a function of temperature reveal the onset of molecular segmental motion known to occur at the glass transition temperature, Tg (∼100°C). Similarly, in Langmuir-Blodgett (L-B) monolayers of cadmium arachidate (CdA), GIR measurements indicate that a two-stage disordering process occurs with increasing temperature. Pretransitional disordering of the hydrocarbon tails may be a contributing factor to the onset of the thermal melting point.
Characterization of Bromine and Chlorine Atomic Emission in a Reduced-Pressure Inductively Coupled (27 MHz) Helium Plasma
Authors: Wolnik K. A. , Miller D. C. , Seliskar C. J. , Fricke F. L.
Published: June 2005

A reduced-pressure 27 MHz inductively coupled plasma (ICP) sustained in helium at low powers (less than 300 W) has been investigated with regard to future application as a selective halogen detector for gas chromatography. The effects of applied power and bulk gas flow rate on neutral and monopositive ionic chlorine and bromine plasma species have been studied. Studies of the optical emission spectra of helium plasmas containing low-molecular-weight organohalogens show that the molecular fragments of the analyte give rise to little radiative background interference. Quantitative results for halogen atomic state populations show that the monopositive species exist in an effectively much hotter plasma environment than the neutral species. A listing of corrected spectral intensities for the most prominent halogen emissions observed from the rf helium plasma over the region 2500 to 7500 Å are given as an appendix.
A Low-Flow Laminar Flow Torch for Microwave-Induced Plasma Emission Spectrometry
Authors: Bruce Mark L. , Workman John M. , Caruso Joseph A. , Lahti Daniel J.
Published: June 2005

The use of the microwave-induced plasma with a new low-flow plasma centering torch has been evaluated. Data were collected through a computer-controlled, background-correcting polychromator system with two versions of the newly developed laminar flow torch. It showed sensitivities slightly better than the 0.5-mm-i.d. capillary quartz open tube torch. Detection limits were between 8 and 60 pg/s for carbon, hydrogen, bromine, chlorine, and fluorine—a considerably improved performance over the tangential flow torch. Torch lifetime and plasma stability are comparable to or better than the high-flow tangential flow torch with three-hour and three-day RSDs of 2% and 6%. Centered plasmas may be sustained with flow rates as low as 5 mL/min.
An Evaluation of Hammett Relationships Derived from Infrared C=N Stretching Data for Aromatic Schiff Bases
Authors: Rafalko J. J. , Choe E. W.
Published: June 2005

Infrared spectra of benzylidene aniline, p-nitrobenzylidene aniline, p-N-dimethylaminobenzylidene aniline, and their 15N-labelled azomethine analogs were obtained to assess the reliability of C=N stretching assignments and Hammett relationships based on these results. The isotopic data indicate that there is extensive mixing of internal coordinates in bands near 1600 cm−1. Bands possessing the greatest C=N stretching character are not always readily distinguishable from aromatic ring breathing modes due to variations in relative intensities and band overlap. Problems related to the use of frequency and intensity data of highly coupled normal modes in Hammett correlations are discussed.
The Use of a Small, Low-Cost FT-IR Spectrometer as a Mobile Analyzer for Fluid Streams
Authors: Compton D. A. C. , Markelov M. , Mittleman M. L. , Grasselli J. G.
Published: June 2005

Infrared analysis is well established as a prime method for identification of unknown samples. However, the instruments needed for recording a complete infrared spectrum have not lent themselves to mobile applications because of their inherent mechanical fragility. The design of a commercial low-cost FT-IR instrument described herein makes it particularly useful as a mobile analyzer since it is optically rugged and has sufficient on-board computer power to record high-quality spectra after being moved between locations. At the same time, it is physically small enough to be mounted on a standard lab cart along with the necessary accessories. We illustrate the use of this mobile, low-cost FT-IR for analyzing the evolved gases from Thermal Gravimetric Analysis, small pilot reactors, and the liquid eluant from Gel Permeation Chromatography.
Inductively Coupled Plasma Emission Lines in the Vacuum Ultraviolet
Authors: Nygaard Danton D. , Leighty David A.
Published: June 2005

Atomic and singly ionic elemental emission lines, observed while 1000 mg/L stock solutions were being nebulized, are listed by element and by wavelength for the spectral region between 160 nm and 200 nm. Relative emission intensities are given for each line, and approximate detection limits are calculated for the most analytically useful lines.
The Laminar Flow Torch for Gas Chromatographic He Microwave Plasma Detection of Pyrethroids and Dioxins
Authors: Bruce Mark L. , Caruso Joseph A.
Published: June 2005

A new laminar flow, microwave-induced plasma torch has been evaluated for its use in gas chromatography. Data were collected through a computer-controlled background-correcting polychromator system. A 0.5-mm-i.d. open quartz tube, the tangential flow torch, and the laminar flow torch were used for discharge containment and were compared. The chromatographic and spectroscopic data were used to determine the partial empirical formulas of pyrethroids and dioxins. The laminar flow torch showed improvements over both the 0.5-mm open tube and the tangential flow torch. The typical errors from the true empirical formulas were less than 4%. Detection limits were between 8 and 60 pg/s for carbon, hydrogen, bromine, chlorine, and fluorine emission signals. The compound detection limits on the carbon channel averaged 0.043 μg/mL for pyrethroids and 0.010 μg/mL for dioxins.
Enhancement of the Surface Modes in Photoacoustic FT-IR Spectroscopy Using a Highly Polarizable Inert Gas
Authors: Urban Marek W. , Koenig Jack L.
Published: June 2005

Fourier transform infrared photoacoustic spectroscopy has been used for the analysis of surface functionality and adsorbed species. Using a highly polarizable gas in the photoacoustic cell and comparing the spectra with a nonpolarizable coupling gas, one can obtain useful information regarding the species present and their orientation with respect to the surface. A highly polarizable inert gas, xenon, enhances those surface modes which are preferentially oriented parallel to the surface and suppresses the intensity of the perpendicular modes. The two types of modes for adsorbed molecules on the oxide surfaces such as silica hare been demonstrated. The intensities of the carbon monoxide mode (parallel to the surface) are greatly enhanced and those of adsorbed water (perpendicular) are suppressed. Surface hydroxyls show less intensity in xenon than helium, reflecting preferentially perpendicular orientation with respect to the surface. This method requires only a routine photoacoustic setup and the use of polarizable and nonpolarizable gases.
Experimental Characterization of Aerosol Production, Transport, Vaporization, and Atomization Systems. Part II: Factors Controlling Aerosol Size Distributions Produced
Authors: Skogerboe R. K. , Freeland S. J.
Published: June 2005

The effects of nebulization conditions on the size characteristics of the aqueous aerosol produced have been investigated for a cross-flow nebulizer. It is shown that the nebulizer gas flow rate does not affect the upper limit mean sizes of the aqueous droplets transported from the nebulization chamber but that the mean size of the analyte-containing aerosol itself is affected. Model equations are presented descriptive of the effects of gas flow rate and analyte concentrations on analyte aerosol size characteristics.
Deconvolution of Mossbauer Spectra by the Finite Impulse Response Operator (FIRO) Method
Authors: Shimokoshi K. , Kanzaki T. , Jones R. Norman
Published: June 2005

The finite impulse response operator (FIRO) method, developed recently by Jones and Shimokoshi [Applied Spectroscopy 37, 59 (1983)] has been applied to the deconvolution of Mossbauer spectra. The overlapped bands of the Mossbauer spectra of iron oxides, formed in the air oxidation of an aqueous suspension of Fe(OH)2, have been deconvolved by the FIRO method in order that the correct positions and intensities of the lines might be defined. The peak positions so determined can be used with good reliability as initial estimates for the customary method of profile determination by a least-squares fitting routine.
The Effect of High-Numerical-Aperture Objectives on Polarization Measurements in Micro-Raman Spectrometry
Authors: Bremard C. , Dhamelincourt P. , Laureyns J. , Turrell G.
Published: June 2005

Polarized Raman spectra of the reference materials carbon tetrachloride and α-quartz are obtained with the Raman microprobe MOLE with the use of different high-numerical-aperture objectives. The depolarization ratios of the Raman bands of isotropic samples are in good agreement with those obtained with the use of conventional instruments, provided that the reflection or transmission factor of the beamsplitter is introduced as a correction. Even with the very wide-aperture objectives used, the depolarization effect is not large and can be evaluated theoretically. Correct polarized spectra of anisotropic samples can also be obtained with a Raman microspectrometer. Here again, the depolarization effect induced by the wide-aperture objective is not large and can be evaluated theoretically if the birefringence of the crystal does not play a significant role. The depolarization induced by the birefringence is especially important when incident and scattered light propagate in a direction close to the optical axis of the crystal, but can be minimized by a reduction of the optical path within the sample.
Measurement of Inductively Coupled Plasma Emission Spectra Using a Fourier Transform Spectrometer
Authors: Stubley E. A. , Horlick G.
Published: June 2005

The qualitative and quantitative capabilities of a Fourier transform spectrometer (FTS) as a measurement system for atomic emission from the ICP are demonstrated. The spectral response of the interferometer from 193 nm to 650 nm is shown to be excellent. Quantitatively, detection limits measured by FTS are poorer by at least an order of magnitude than those obtained with a commercial direct reader-based ICP instrument. Factors affecting the quantitative performance of FTS— dynamic range limitations and the multiplex disadvantage—are discussed and a method to improve the quantitative capabilities of FTS is suggested.
Determination of Polydimethylsiloxane on Cotton Fabrics Using Fourier Transform Attenuated Total Reflection Infrared Spectroscopy
Authors: Murthy R. S. Shreedhara , Leyden D. E. , D'Alonzo R. P.
Published: June 2005

Polydimethylsiloxane (PDMS) was chosen as a model siloxane molecule so a method could be developed for its quantification on cotton fabric with the use of ATR/FT-IR spectroscopy. PDMS is transferred onto an ATR crystal in the presence of methanol under pressure. This eliminates strong spectral interference from cellulose and improves precision. Methanol was needed to swell the fibers to release PDMS. The method is more sensitive, rapid, and nondestructive compared to extraction and transmission techniques.
Quantitative Applications of Photothermal Beam Deflection Photoacoustic Spectrometry
Authors: Field R. S. , Leyden D. E. , Masujima T. , Eyring E. M.
Published: June 2005

Quantitative measurement of a mixture of silica gel with a surface immobilized Cu(II) complex and unmodified silica gel is demonstrated with the use of photothermal beam deflection detection of the photoacoustic signal. A photoacoustic response function utilizing both magnitude and phase information is required in order for one to obtain a linear relationship between response and concentration.
Surface Studies of Coal, Oil, and Coal-Oil-Mixture Ash Using Auger Electron Spectroscopy and Solvent Leaching Techniques
Authors: Stinespring Charter D. , Harris Wesley R. , Cook Jason M. , Casleton Kent H.
Published: June 2005

Fly ashes produced by the combustion of coal, oil, and a coal-oil mixture have been studied by Auger electron spectroscopy and solvent leaching techniques. The Auger data indicate that the surface concentration of the metal ions Na, Fe, Mg, Ni, V, and Al as well as S and C increases on going from coal to coal-oil mixture and oil ash. The relative surface enrichments of oil and coal-oil-mixture ash are consistent with a simple model of the ash-formation process, and the results confirm that several toxic metals are significantly enriched on the surface of the ash particles. The Auger data are compared to HCl and tris buffer leachate composition analyses, and in neither case does the leachate give an accurate representation of the surface composition. HCl apparently dissolves large oxide deposits and thus overestimates the surface concentrations of Fe, AI, and V. Conversely, several metallic ions are essentially insoluble in neutral aqueous solutions, so their surface concentration is underestimated by the tris leachate.