bluuebunny/crossref_metadata_2025 huggingface dataset:
Multichannel Densitometry of Gas Electron Diffraction Patterns
Authors: Benston O. Joel , Ewbank John D. , Paul David W. , Klimkowski V. Joseph , Schäfer Lothar
Published: July 2005

The use of a multichannel linear photodioide array in obtaining diffraction intensities from photographic gas electron diffraction (GED) records is described. A commercially available RETICON 1024-channel linear array together with its programmable controller (EG & G models 1412 & 1218) combined with a MINC DECLAB-23 have been tested in this novel procedure of GED plate densitometry. One complete radial intensity distribution (plate image) is obtained every 16 ms from either a spinning or manually adjusted plate and can be dynamically viewed on an oscilloscope or digitally graphed on the DEC system monitor. This rapid data acquisition presents powerful and efficient means whereby plate centering, curve averaging, parametric refinement, and other data management can be conveniently conducted. Test analyses document that results obtained by this method are accurate and reproducible. The success of this new approach suggests the use of photodiode arrays in dynamic data acquisition systems of GED requiring no photographic intermediary, either by direct exposure of the diode array to scattered electrons, or by immediate acquisition of optical intensities from a fluorescent screen illuminated by electron impact.
Measurements of the Optical Anisotropy of Trapped Molecules in Oriented Polymer Films by Waveguide Raman Spectroscopy (WRS)
Authors: Schlotter N. E. , Rabolt J. F.
Published: July 2005

The orientation of small molecules trapped in a polymer matrix has been studied by Raman spectroscopy using integrated optical techniques. Results indicate that the orientation of the trapped molecules occurs during mechanical processing of the polymer film and may contribute artifacts to the observed birefringence since solvent molecules are often trapped and oriented during preparation. When the guest molecule was naphthalene, the disappearance of crystal field splitting in the Raman spectrum suggested that an interruption of the intermolecular forces had occurred upon embedding the molecule in a polystyrene matrix. The ability to orient isolated naphthalene molecules indicates that this technique is ideal for studying oriented molecules in a polymer film in the absence of crystal field interactions.
Effect of Pressure on Diffuse Reflectance Infrared Spectra of Compressed Powders
Authors: Yeboah S. Agyare , Wang Shih-Hsien , Griffiths Peter R.
Published: July 2005

The effect of compressing powdered samples on their diffuse reflectance infrared spectra is discussed. The scattering coefficient decreases with applied pressure, the magnitude of the increase being dependent on the nature of the sample. For pure powdered organic samples, such as caffeine, the increase in f(R∞) can be dramatic. By subjecting powdered samples to a pressure which is not enough to cause them to become transparent, the packing density becomes more uniform and band intensities become more reproducible. The relative intensity of neighboring bands in any region of the spectrum does not change appreciably with applied pressure.
The Role of Reflectance in the Photoacoustic Spectra of Copper, Silver, and Gold
Authors: Hodul David , Carlson K. Douglas
Published: July 2005

The photoacoustic (PA) spectra were determined over the wavelength region of 1000–200 nm for polished and etched foils and powders of Cu, Ag, and Au. Aside from differences in signal strengths, problems with abnormal signal distortions due to reflection, and problems with surface oxidation in powdered Cu, the spectra were basically the same for the foils and powdered samples of the same metal. Analyses of the spectra showed that the PA signals were proportional to (1 – R), where R is the regular reflectance of the metal. Thus, the PA spectra were essentially reflectance loss spectra.
Slurry Atomization Direct Flame Emission Determination of Na and K in Hot Dogs
Authors: Fietkau R. , Wichman M. D. , Fry R. C.
Published: July 2005

This report describes initial development of a slurry atomization method for rapid, cost-effective, near-direct determinations of sodium and potassium in hot dogs by flame emission. Samples were briefly homogenized in water. Na and K were thereby solubilized. Hot dog slurries were directly introduced with a Babington nebulizer into a clog-free air-natural-gas burner. This cool flame eliminated ionization. Instrumental calibration was performed merely with separate aqueous standard solutions of NaCl and KCl. Ionization suppressants, internal standards, standard additions, matrix correction factors, matrix modifiers and matrix matching schemes were all found to be unnecessary for hot dog slurries directly analyzed with this system. The overall slurry atomization method eliminated the need for acids, fume hoods and lengthy sample preparation such as wet or dry ashing. Quantitative accuracy was achieved for near-direct determinations of weight percent Na and K in hot dogs. Total solid sample preparation plus analysis times were ≤ 5 min.
The Shape of Analytical Curves in Zeeman Atomic Absorption Spectroscopy III: Extended Dynamic Range
Authors: De Loos-Vollebregt M. T. C. , De Galan L.
Published: July 2005

The analysis of the shape of analytical curves in Zeeman atomic absorption spectroscopy has been extended towards very high concentration. Beyond the absorption maximum the slope of the Zeeman analytical curve depends on the remaining absorption at maximum field strength. The absorbance and concentration at roll-over can be estimated from the initial slope of the Zeeman analytical curve at low concentration and the decreasing part of the curve at very high concentration. It is shown that the dynamic range of atomic absorption analytical curves can be readily extended with an ac Zeeman system. Analytical curves of reduced sensitivity are obtained when the maximum field intensity measurement is combined with a measurement at intermediate field strength rather than at zero field strength. However, the maximum absorbance in the extended range Zeeman analytical curve is lower than in the normal Zeeman analytical curve.
The Vibrational Spectrum of Isotactic Polystyrene I: Normal Coordinate Calculations of the Completely Deuterated Polymer
Authors: Painter Paul C. , Howe Stephen E. , Coleman Michael M.
Published: July 2005

The normal modes and dispersion curves of completely deuterated isotactic polystyrene (IPS-d8) have been calculated using a previously developed force field. A good agreement was found between the calculated frequencies and those observed in the experimental infrared and Raman spectra. The results obtained are important to our subsequent study of the effect of mass defects on the vibrational spectrum of IPS.
Optimization of Time Resolved Phosphorimetry
Authors: Barnes C. G. , Winefordner J. D.
Published: July 2005

Time resolution, in spite of its enormous potential for minimizing spectral interferences in analytical phosphorimetry, has never achieved the widespread application that one might expect. One reason has been the inefficient trial-and-error optimization of the pulsed source gated detection phosphorimeter for a given analysis. In this paper, this problem is addressed by deriving expressions which relate the observed phosphorescence intensity to the temporal characteristics of the experimental system, and using these expressions to ascertain how the individual adjustable parameters, coupled with the analyte lifetime(s), affect the observed intensity. The predicted effects are verified by comparison with experimental results obtained on several phosphors of widely different lifetimes, using a pulsed laser boxcar averager phosphorimeter.
Vibrational Spectra, Assignments, and Valence Force Field for S-nitrosocysteine and Isotopic Analogs
Authors: Byler D. Michael , Susi Heino , Gerasimowicz Walter V.
Published: July 2005

S-nitrosocysteine and the isotopically-substituted S15NO and N- d3 analogs have been prepared. FT-IR spectra have been obtained on the normal molecule and the 15N isotopomer. Spectra of the N- d3 analog were obtained with a dispersive instrument. The fundamental frequencies of the three isotopomers were calculated by using force constants previously obtained through overlay calculations on amino acids and from a normal coordinate analysis of methyl thionitrite. The average computational error between the observed and calculated frequencies using the transferred force constants was 11 cm−1. This difference was decreased to 7 cm−1 by slightly modifying some of the force constant values by a least-squares refinement. Vibrational assignments are made for all three isotopic analogs by utilizing the potential energy distribution. Out of a total of 96 fundamentals occurring above 300 cm−1, 65 may be classified as group vibrations by the potential energy criterion.
Temperature and Electron Density Measurements in a DC Glow Discharge
Authors: Brackett John M. , Mitchell Joel C. , Vickers Thomas J.
Published: July 2005

Data on the glow discharge have been accumulated by photographic detection with an echelle spectrometer. Intensity, excitation temperature, and electron density results are reported for the cathode dark space, negative glow, and Faraday dark space regions of the plasma for three values of discharge current and five values of fill gas pressure. It is concluded that neither excitation temperature nor electron density is a useful descriptor of excitation conditions in low pressure plasmas. Excitation is interpreted in terms of an ionization-radiative recombination model, and intensity of argon atomic emission is shown to be correlated with the product of discharge current and argon ionization cross section.
IR Study of Amorphous Silicon Nitride Films
Authors: Luongo J. P.
Published: July 2005

Deposited films of amorphous silicon nitride, Si3N4, which are used for surface protection or as an insulating interlayer in microelectronic devices, have been studied by IR. The observed changes in the vibrational frequency location of the broad infrared Si-N antisymmetrical stretching absorption in the spectra of various plasma deposited Si3N4 films indicate the formation and inclusion of impurities within the silicon nitride network. The deposited films are composed principally of amorphous Si3N4, but trace amounts of hydrogen-, oxygen-, and nitrogen-containing moieties were found which contributed to the displacement of the Si-N absorption. The associated functional groups were identified as Si-H, NH, SiOx, and Si-O-Nx. IR was used to measure quantitatively the hydrogen-containing impurities. The method provides a means of identifying and correlating impurity levels with properties of the films.
Adaptive Smoothing of Spectroscopic Data by a Linear Mean-Square Estimation
Authors: Kawata Satoshi , Minami Shigeo
Published: July 2005

An adaptive smoothing method based on a least mean-square estimation is developed for noise filtering of spectroscopic data. The algorithm of this method is nonrecursive and shift-varying with the local statistics of data. The mean and the variance of the observed spectrum at an individual sampled point are calculated point by point from its local mean and variance. By this method, in the resultant spectrum, the signal-to-noise ratio is maximized at any local section of the entire spectrum. Experimental results for the absorption spectrum of ammonia gas demonstrate that this method distorts less amount of signal components than the conventional smoothing method based on the polynomial curve-fitting and suppresses noise components satisfactorily. The computation time of this algorithm is rather shorter than that of the convolution algorithm with seven weighting coefficients. The a priori information for the estimation of the signal by this method are: the variance of noise, which can be attainable in the experiment; and the window function which gives the local statistics. The investigation of various types of window functions shows that the selection of the window function does not directly affect the performance of adaptive smoothing.
Polarized Infrared Attenuated Total Reflection Spectra of Powders
Authors: Barbetta Angelo J.
Published: July 2005

Attenuated Total Reflection infrared spectra were obtained for rough and spheroidal powders made from an amorphous polymer. The spectra were recorded with a polarizer to obtain both parallel and perpendicular components of the spectra separately. The results were compared to both theoretical predictions and experimental results for the same material examined as a film. It was found that the relative absorption intensities of the two polarization spectra recorded of the film agreed well with the theory for films. However, the powdered samples showed unexpected increases in absorption intensities for the perpendicular spectra. The intensities of the absorptions for perpendicular polarization were about 45% greater than for films as measured by the ratio of relative effective thicknesses. Implications for interpretation of the spectra of powdered materials are discussed.
Nondestructive FT-IR Sampling Technique to Study Glass Fiber Composite Interfaces
Authors: Culler S. R. , Ishida H. , Koenig J. L.
Published: July 2005

A nondestructive FT-IR sampling technique was developed to study glass fiber composites. Two coupling agents, γ-APS (γ-aminopropyltriethoxysilane) and γ-MPS (γ-methacryloxypropyltrimethoxysilane) were used to test the validity of the technique. The spectra obtained were compared with those obtained using the KBr pellet and diffuse reflectance techniques. The new technique was sensitive to changes in the coupling agent structure induced by heating, changing the drying environment, and pH. This technique could be used to monitor surface treatments on glass mats or to do quantitative studies of such systems in the 3800 to 1100 cur−1 range of the mid-infrared spectrum.
Infrared Spectroscopy of Aqueous Antibiotic Solutions
Authors: Wong James S. , Rein Alan J. , Wilks Donald , Wilks Paul
Published: July 2005

Infrared spectra of aqueous antibiotic solutions were obtained using a new Liquid Analyzer accessory in a Fourier transform infrared (FT-IR) spectrometer. Based on a cylindrical internal reflectance element, the Liquid Analyzer accessory provides a sufficiently short (∼0.015 mm) effective pathlength for infrared spectroscopy of aqueous solutions from 3200 to 800 cm−1, Spectra of aqueous solutions of penicillin VK, sodium oxacillin and sodium methicillin are shown. By measuring the absorbante of the beta-lactam carbonyl band, FT-IR spectroscopy with the accessory exhibits analytical sensitivity to less than 0.1% concentration by weight of antibiotic both in aqueous solution and in an actual fermentation broth.
Optical Fiber Fluoroprobes for Biological Measurements
Authors: Tromberg Bruce J. , Eastham Jerome F. , Sepaniak Michael J.
Published: July 2005

An optical fiber fluoroprobe has been designed to make in vivo fluorescence measurements in minute volumes of body fluids. The fluoroprobe is evaluated for conventional laser excited, two-photon excited, and sequentially excited modes of fluorescence detection. Limits of detection, approximately 5 × 10−7 M, were determined for test compounds measured in various solvents including cerebral spinal fluid and whole blood, and are comparable for the three fluorescence techniques. Linear dynamic ranges are shown to be solvent dependent and superior for the nonlinear excited fluorescence techniques. The ultimate detectability and selectivity of this technique are also discussed.
Correction of Nonlinear Derivative Diode Laser Data in Standard Addition Analyses
Authors: Mucha J. A.
Published: July 2005

Modulation techniques are widely used for derivative presentation of spectral lines for lineshape studies and quantitative analyses. Modulation amplitudes generating the most acceptable signal-to-noise ratios produce distortion in the recorded spectrum and alter the apparent linewidth and absorptivity of the band. Methods of determining modulation-broadened linewidths and absorptivities relative to their molecular values are presented for 2nd-derivative spectra of Doppler limited (Gaussian lineshape) infrared transitions of water vapor. The results are discussed in terms of using the effective absorptivities for correcting derivative data that no longer scale linearly with absorber concentration.
The Detection Capabilities of Fourier Transform External Reflection and Photoacoustic Spectroscopy for Electrode-Supported Films
Authors: Porter Marc D. , Karweik Dale H. , Kuwana Theodore , Theis William B. , Norris George B. , Tiernan Thomas O.
Published: July 2005

Fourier transform infrared external reflection and photoacoustic spectroscopy has been used for the vibrational characterization of a Prussian Blue (PB) film on Pt and a cupric hexacyanoferrate (CuHCF) film on glassy carbon (GC) irradiated at normal incidence. Since the optical response appeared to be substrate dependent, the mean-square electric fields as a function of the optical constants of the substrates (Pt, GC) and the films (PB, CuHCF) were calculated. The results of these calculations, used with the experimentally determined signal-to-noise ratios, were employed to predict film detection limits. It was found that the electric field intensity near the CuHCF/GC interface was much greater than that near the PB/Pt interface. For this reason, the film thicknesses detectable by these spectroscopic methods are lower at the interface of the GC substrate than at the Pt substrate.
Optical Purity Determination and 1H NMR Spectral Simplification with Lanthanide Shift Reagents. II. Thiamylal, 5-Allyl-5-(1-methylbutyl)-2-thiobarbituric Acid
Authors: Eberhart S. , Rothchild R.
Published: July 2005

A racemic sample of thiamylal, 5-allyl-5-(1-methylbutyl)-2-thiobarbituric acid, 1, has been shown to exhibit significant enantiomeric shift differences, ΔΔδ, for the CH3- CH proton absorptions when treated with the chiral lanthanide shift reagent, tris[3-(trifluoromethylhydroxy-methylene)- d-camphorato| europium (III), 2, in CDC13 at 28°. For example, at the relatively low molar ratio of 2:1 of 0.181, a value of ΔΔδ of 22 Hz (0.36δ) was observed, which increased to 26 Hz (0.43δ) at a molar ratio of 0.226. These large values, with relatively little lanthanide-induced line-broadening, should make possible the facile determination of optical purity of 1 even with a 60 MHz nmr spectrometer. Parallel studies were run using the achiral shift reagent, tris-(6,6,7,7,8,8,8-heptafluoro-2,2-dimethyl-3,5-octanedionato) europium (III), 3, to confirm peak assignments. The considerable values of ΔΔδ may reflect the “soft base” character of the sulfur atom in 1. Less effective binding by sulfur to the lanthanide atom could lead to coordination by europium on the carbonyl oxygen, relatively close to the chiral center, providing enhanced AA5 values compared to some related compounds. While several other proton absorptions of 1 appear to show some observable ΔΔδ, they are less valuable for optical purity evaluation because of lower intensity, greater multiplicity, or small ΔΔδ value. The relative slopes of the plots of chemical shift, δ, for runs with 2 or 3, are consistent with the full assignment of the proton absorptions of 1 based on expected proximity of the protons to the complexed europium atom. The observed coupling constants of the vinyl hydrogens of 1 further support the assignments.
Measurement of the IR-ORD of Induced Cholesteric Solutions in Presence of Linear Dichroism
Authors: Tsankov D. , Jordanov B. , Korte E. H. , Schrader B.
Published: July 2005

The sign of absorption-induced Cotton effects in the IR-ORD spectra of induced cholesteric solutions allows us to distinguish between enantiometric solutes. It is shown here that the often distorted shape of these rotatory anomalies, sometimes making the evaluation ambiguous (in particular for highly diluted solutions), is due to the superimposition of a linear dichroism band and that this can be compensated for by appropriate orientation of the sample. In this way the necessary quantity of optically active solute can be lowered considerably.
Application of Spectral Subtraction Technique to Solid Samples of HCOONa and CH3COONa with Small Amounts of D-variants
Authors: Kakihana Masato , Okamoto Makoto
Published: July 2005

The spectral subtraction technique was applied to solid samples of HCOONa and CH3COONa along with small amounts of D-variants. The weak signals due to the D-species heavily overlapped by strong absorption bands from the H-species were separately observed by removing the interfering absorbances of the H-substances from the composite spectra of the isotopic mixtures. The best result was achieved when the homogeneity of the sample thickness and composition was satisfactory.
A Raman Spectrometer-Minicomputer Data Acquisition and Analysis System
Authors: Snyder Robert W. , Hooker Thomas M.
Published: July 2005

A minicomputer-based hardware and software system has been developed for the acquisition and analysis of Raman spectra. The interface is capable of controlling a Cary 82 laser-Raman spectrometer or other similar units. Software routines have been developed for instrument control and data acquisition and for the analysis and manipulation of Raman data. Routines for baseline correction, peak finding, and curve fitting have been investigated. Data smoothing techniques, including Fourier analysis methods, have also been utilized.
Infrared Photoacoustic Spectroscopy of Conducting Polymers III. Polyparaphenylene and its Derivatives
Authors: Aniger Stuart I. Y. , Rose David J. , McKenna William P. , Eyring Edward M.
Published: July 2005

Fourier Transform Infrared Photoacoustic (FT-IR/PA) spectroscopy provides a means to obtain high quality spectra of polyparaphenylene (PPP), an organic semiconductor. Spectra of PPP prepared by two different methods, heavily n-doped PPP, and a new organometallic derivative, PPP(Mo(CO)3)0.25 are presented. Spectral acquisition times for these polymers can be as low as one minute.
Long Path Length Temperature-Controlled Absorption Cell for Spectroscopic Studies of Radioactive Compounds
Authors: Briesmeister R. A. , Read G. W. , Kim K. C. , Fitzpatrick J. R.
Published: July 2005

A unique long-path absorption cell has been developed for spectroscopic studies of alpha radioactive compounds. The cell is temperature programmable from room temperature down to 100 K and has an optical path length up to 0.5 km. Special design features and performance characteristics are described.
FT-IR/PAS Investigation of Chromocene Supported on Silica
Authors: McKenna William P. , Bandyopadhyay Saibal , Eyring Edward M.
Published: July 2005

Chromocene anchored on silica has been investigated by Fourier transform Infrared photoacoustic spectroscopy (FT-IR/PAS). The mid Infrared spectrum of this olefin polymerization catalyst has been obtained before and after treatment with ethylene. A model complex for a key intermediate in the olefin polymerization has been observed. The design of a vacuum jacketed PA cell for use in a vacuum bench FT-IR spectrometer is also presented.
Fourier Transform Diffuse Reflectance Infrared Study of Polymer Films and Coatings: A Method for Studying Polymer Surfaces
Authors: Culler S. R. , McKenzie M. T. , Fina L. J. , Ishida H. , Koenig J. L.
Published: July 2005

Diffuse reflectance FT-IR (DRIFT) is described as a tool for the study of polymer surfaces. The high sensitivity (particularly to surfaces) and nondestructive sample preparation procedure used for DRIFT experiments are valuable characteristics of the technique. By the use of an overlayer of a nonabsorbing powder such as KBr, the quality of the spectra of coatings and surface species on absorbing substrates is improved. We performed a model study using multilayer polymer films in order to understand the optimal applicability of DRIFT to these measurements. The relative contribution of the surface to the spectra can be adjusted by varying the amount and/or particle size of the KBr powder overlayer. Correlations between particle size, overlayer amount, and nature of the spectra of the “model” system are discussed. Practical examples of the application of this novel approach are presented.
Curve Fitting Analysis of ESCA Ni 2p Spectra of Nickel-Oxygen Compounds and Ni/Al2O3 Catalysts
Authors: Li Chung Ping , Proctor Andrew , Hercules David M.
Published: July 2005

Nonlinear least-squares curve fitting is used to analyze Ni 2p spectra obtained from various nickel-oxygen compounds and Ni/Al2O3 catalysts. Apart from NiO, which shows a characteristic discrete satellite peak 2 eV from the main 2p3/2 peak, all other spectra exhibit variable peak asymmetry assigned to multiplet splitting effects. By the use of a single extra peak to describe this asymmetry, the relative satellite/main peak intensity ratio can be used as an indication of the chemical state of nickel. Results for Ni/Al2O3 catalysts agree with reduction studies from previous work about the nature of nickel species on the surfaces of these catalysts at various nickel loadings.
Applications of Diffuse Reflectance FT-IR to the Characterization of an E-Glass Fiber/γ-APS Coupling Agent System
Authors: McKenzie M. T. , Culler S. R. , Koenig J. L.
Published: July 2005

The utility of diffuse reflectance FT-IR (DRIFT) spectroscopy is explored to study the surfaces of clean E-glass fibers and E-glass/coupling agent systems. The ability to use a nondestructive sampling procedure is an important benefit for the study of these systems. However, the nature of the fiber samples leads to several experimental difficulties. We solve these problems through the use of a KBr overlayer. Using this sample-preparation procedure, we increase the information derivable from the spectra. The inherent surface sensitivity of the DRIFT technique is demonstrated by the study of small amounts of the silane coupling agent γ-aminopropyltriethoxysilane (γ-APS) on the surface of E-glass fibers.
Optimization of GC/FT-IR Measurements I: Construction of Light-Pipes
Authors: Yang P. W. J. , Ethridge E. L. , Lane J. L. , Griffiths P. R.
Published: July 2005

Conditions under which light-pipes with highly reproducible transmittance are prepared are described. Preparation of borosilicate glass tubing by washing with HF and SiCl2 solutions gave the best results. Electron microscopy showed that drawn capillary tubing had a much smoother bore than “precision-bore” (drilled) tubing, and light-pipes constructed from drawn tubing had a much higher transmittance. Annealing the tubes at 800°C appeared to cause the gold coating to be more tightly held to the glass tubing. Light-pipes which had been annealed at 800°C could have small holes drilled through the tube without the gold coating lifting.
Application of Fourier Self-Deconvolution to Vibrational Circular Dichroism Spectra
Authors: Lipp Elmer D. , Nafie Laurence A.
Published: July 2005

The resolution enhancement technique of Fourier self-deconvolution is applied to vibrational circular dichroism spectroscopy. Spectra of (+)−3-methylcyclohexanone recorded at different resolutions are used to show how the technique enhances resolution without the production of artifacts. The spectrum of (+)-limonene is presented as an example of a severely congested spectrum which shows dramatic changes upon deconvolution. Application of the technique to difference spectroscopy in general appears to be a valuable method for retrieving information lost through band overlap.
A Comparison of Signal-to-Noise Ratios for Near-Infrared Detectors
Authors: Freeman J. E. , Hieftje G. M.
Published: July 2005

Five detectors sensitive in the near-Infrared, including two photomultiplier tubes, a silicon photodiode, a silicon photodiode array, and a lead-sulfide photoconductor, are evaluated in terms of signal-to-noise ratios. Theoretical noise and signal calculations are compared to measured noise values and relative responses. The spectral response of the detectors between 700 and 1200 nm is also reported. The relative merits of a particular detector are a function of wavelength, photon flux, and other criteria.
Intracavity Atomic Absorption with an Inductively Coupled Plasma Atomizer
Authors: Downey S. W. , Nogar N. S.
Published: July 2005

An inductively coupled plasma is placed inside the cavity of a flashlamp-pumped dye laser and atomic absorption is measured with the use of an optogalvanic detector. An enhancement factor of 170 is shown for intracavity absorption relative to single-pass, extracavity absorption. Both atom and ion lines can be monitored by this technique. Detection limits of 1 µg/mL for sodium and 0.1 µg/mL for barium were observed. The major noise source is pulse-to-pulse fluctuation in the laser output.
FT-IR Spectroscopy in an Industrial Laboratory
Authors: Chalmers J. M. , Mackenzie M. W. , Willis H. A.
Published: July 2005

FT-IR spectroscopy is used widely in many industrial laboratories. In combination with techniques such as gas chromatography, diffuse reflectance, and photoacoustic spectroscopy, it provides a means of tackling certain problems which would be impossible or at least very difficult and time-consuming with the use of dispersive Infrared instrumentation. This paper describes several examples in which FT-IR has proved to be of considerable value in dealing with problems from the research, development, and production areas of the plastics industry.
Number of Samples and Wavelengths Required for the Training Set in Near-Infrared Reflectance Spectroscopy
Authors: Honigs D. E. , Hieftje G. M. , Hirschfeld T.
Published: July 2005

Near-infrared reflectance spectroscopy uses a learning algorithm to derive a set of weighting coefficients from the reflectance spectra of a reference sample set. These coefficients, when applied to the reflectance values of an unknown sample at specific wavelengths, can be used to calculate constituent concentrations. Having enough samples in the training set and enough wavelengths in the calculation procedures is essential, but there are severe drawbacks to picking too large a number. This paper describes the principles and implementation of a working procedure for objectively calculating the minimum number of training samples required.
Optimization of GC/FT-IR Measurements II: Optical Design
Authors: Yang P. W. J. , Griffiths P. R.
Published: July 2005

Several optical designs for GC/FT-IR have been investigated. It was found that reflection losses occurring in the light-pipe cause the solid angle of the emerging beam to be much smaller than that of the input beam. This property permits a very small image at the detector to be achieved since the collection mirror may be mounted well away from the end of the light-pipe. With an optical configuration of this sort, the effect of radiation emitted from the light-pipe saturating the response of the detector is also minimized.
Laser-Induced Fluorescence Studies of Hematoporphyrin Derivative (HPD) in Normal and Tumor Tissue of Rat
Authors: Ankerst J. , Montán S. , Svanberg K. , Svanberg S.
Published: July 2005

Fluorescence studies of hematoporphyrin derivative (HPD) in normal and tumor tissue of rat were performed with nitrogen laser excitation and optical multi-channel detection. Fifteen types of tissue including inoculated tumor were investigated for rats at different delays after HPD injection. Optimum contrast functions and other criteria for discriminating tumor tissue from normal tissue are discussed. The results should have implications for practical human HPD endoscopy.
Optimum Instrumental Resolution in Condensed Phase Infrared Spectroscopy
Authors: Kauppinen Jyrki K.
Published: July 2005

The optimum instrumental resolution is defined in the case where the instrumental profile width is smaller than the spectral band width. The formulae for the optimum condition are derived as a function of the signal-to-noise ratio with the use of sinc, sinc1, triangular, and Gaussian shapes as instrumental functions. The results reveal the resolving power advantage of Fourier transform spectroscopy, which is emphasized and compared to grating spectroscopy.
A Review of Instrumentation Used to Generate Microwave-Induced Plasmas
Authors: Goode Scott R. , Baughman Kim W.
Published: July 2005

The development and the design of instrumentation used to generate a microwave-induced plasma (MIP) is reviewed. Microwave power generators, coupling devices, discharge tubes, and their influence on the spectrochemical utility of the MIP are described. A complete analysis of the widely used TM010 cavity is also presented.
Optical Purity Determination and 1H NMR Spectral Simplification with Lanthanide Shift Reagents III: Ethotoin, 3-Ethyl-5-Phenyl-2, 4-Imidazolidinedione
Authors: Avolio John , Rothchild Robert
Published: July 2005

The 60 MHz 1H NMR spectra of racemic ethotoin, a, have been studied with the achiral shift reagent tris(6,6,7,7,8,8,8-heptafluoro-2,2-dimeth-yl-3,5-octanedionato) europium (III), b, and the chiral tris[3-(rrifluoromethylhydroxymethylene)- d-camphorato] europium (III), c Appreciable values of the enantiomeric shift difference, ΔΔδ, were observed for the NH, CH3, CH, and ortho aryl protons in CDCl3 solutions at 28°C with the use of samples about 045 molal in a Optical purity assays should be feasible with the use of the NH or CH3 absorptions that display ΔΔδ of 224 and 70 Hz, respectively, at a c:a molar ratio of about 03, with the former resonance being optimal With a c:a ratio between 04–05, the methine proton can be used, with ΔΔδ 11 – 13 Hz Results are interpreted in terms of major coordination of the europium at the C-2 oxygen
A High Throughput Optical Accessory for Improved Measurement of the Infrared Spectra of Diffusely Scattering Samples: Description and Assessment
Authors: Jakse Frank P. , Friedman Robert Mark , Freeman John J.
Published: July 2005

The performance of a high throughput optics bench (HTOB) was compared to the conventional collection optics of an FT-IR spectrometer Samples were studied as pressed KBr wafers or self-supporting wafers The former sample preparation suppresses scattering but limits adsorption studies for these samples; in this instance, the HTOB showed no distinct advantage over the straight transmission (STTR) optics For samples exhibiting significant scattering, the modified optics showed a ∼5/l improvement in signal-to-noise for the transmission spectrum compared to that obtained in the conventional configuration This offers a 25-fold reduction in data collection time for comparable spectra This amelioration was graphically demonstrated in the study of adsorption of n-butylamine on titania The relative contribution of the components of the HTOB to the improvement, the limitations of the accessory, and the range of applicability are discussed
An FT-IR Microspectroscopic Method for Kinetic Measurements at High Temperatures and High Pressures
Authors: Miller P. J. , Piermarini G. J. , Block S
Published: July 2005

A Fourier transform infrared microspectroscopic method has been developed for obtaining kinetic data as a function of pressure and temperature The method employs a diamond-anvil high-pressure cell with heating capability, in conjunction with an FT-IR spectrometer modified with an on-axis cassegrain-type beam condenser Time-dependent absorption spectra have been obtained for the thermal decomposition of 1,3,5-trinitrohexahydro-1,3,5-triazine (RDX) as a function of pressure and temperature The pressure dependence of the temperature of thermal decomposition has also been determined The method has wide applicability to kinetic measurements in general
ICP Emission Spectra III: The Spectra of the Group IIIA Elements and Spectral Interferences Due to Group IIA and IIIA Elements
Authors: Anderson T. A. , Parsons M. L.
Published: July 2005

The spectra of the group IIIA elements observed in an ICP have been tabulated in the wavelength range from 1995 to 6005 Å These spectra have been compared to a list of those analytical lines most commonly used for the 71 elements analyzed for by an ICP The results of these comparisons have been used to develop spectral interference tables which predict those spectral interferences due to the group IIIA elements in ICP spectroscopy In addition, the spectral interferences due to the alkaline earth elements have been included
Determination of Trace Elements in Serum Using Inductively Coupled Plasma Atomic Spectroscopy with Hydride Generation and Chelating Resin Preconcentration
Authors: Mianzhi Zhuang , Barnes Ramon M.
Published: July 2005

A procedure is described for the inductively coupled plasma emission spectroscopic determination of Cd, Co, Cu, Fe, Mo, V, and Zn in < 1 mL of serum after digestion in nitric and perchloric acids and preconcentration with a poly(dithiocarbamate) resin Recoveries are 91 to 106% The determination of As and Se in serum by hydride generation and ICP-AES is performed after the interference of Cu on Se hydride generation was reduced by complexation of the Cu with poly(acrylamidoxime) resin Verification with NBS-SRMs as well as with human sera samples is reported
Full Automation of Infrared Qualitative Analysis of Binary Mixtures by Use of a Spectral Curve Compilation
Authors: Saëki Shinnosuke , Tanabe Kazutoshi
Published: July 2005

A project for the compilation of infrared spectral curves is now in progress at the National Chemical Laboratory for Industry, Japan On the basis of this compilation, a computer program has been developed for the full automation of infrared qualitative analysis of binary mixtures by means of the correlation coefficient method The program has been applied to six binary mixtures Four of them had resolutions as high as that in file spectra, and the other two, which were prepared from the former by convolution, had lower resolution The correct answers have been obtained automatically in all cases The CPU time necessary for the running of this program was from 60 to 90 seconds with the use of a FACOM M200 computer system
Fourier Transform Spectrometry in the Far-Infrared to High-Microwave Spectral Region Using a Rapid-Scan Interferometer
Authors: Richter W
Published: July 2005

An experimental set-up, based on a commercial rapid-scan Fourier transform spectrometer, for dielectric loss measurements on low-loss materials in the frequency region between 120 GHz and 1650 GHz (4–55 cm−1) is described Results obtained for cyclohexane are presented as an example of application
Low-Temperature Infrared and Raman Spectra of Co(CH3COO)2·4X2O (X = H, D)
Authors: Raghuvanshi G. S. , Khandelwal D. P. , Bist H. D.
Published: July 2005

The infrared spectra (4000–200 cm−1) at 300 K and 95 K, and Raman spectra (4000–40 cm−1) at 300 K and 130 K of the titled compounds are reported A varying degree of deuteration has been used to assign the modes of water Analysis of the spectra confirms the known structure that has one type of acetate ion and two types of water groups in the unit cell H2O(I) retains approximately C2 v symmetry while H2O(II) is distorted to C s
Enhancement Errors in the Determination of Platinum Group Metals in Alumina-Based Matrices by Direct-Current Plasma Emission Spectrometry
Authors: Fox Roberta L.
Published: July 2005

Direct-current plasma emission spectrometric analysis of platinum group metals in solutions from automobile catalyst shows significant enhancement of analyte values Addition of a lithium buffer does not remove the interference The only matrix constituents in these solutions were aluminum and magnesium, both of which were found to cause enhancement in the determination of platinum, palladium, and rhodium A buffer consisting of 3500 mg/L lithium and 2500 mg/L lanthanum removed the enhancement effect of both magnesium and aluminum on these metals 8-hydroxyquinoline also reduced the degree of interference due to aluminum, although not as efficiently as lanthanum, indicating that formation of compounds in the dc plasma is a possible source for the observed interference
Fourier Transform Infrared Spectrometer Coupled with Electrothermal Atomizer for High-Temperature Vapor-Phase Investigations
Authors: Tittarelli Paolo , Zerlia Tiziana , Ferrari Giovanna
Published: July 2005

An electrothermal atomizer is employed to vaporize solid samples of pigments at temperatures ranging from 150°C to 1000°C The evolution of vapors is followed by Fourier transform infrared spectrometry (FT-IR) The atomizer acts at the same time as vapor supplier and vapor holder This coupling allows the investigation in situ of vaporization or pyrolysis phenomena avoiding the use of heated transfer pipes The pigments examined in this study show various vapor-phase behaviors Some pigments vaporize without appreciable decomposition at temperatures from 400°C to 950°C, while other pigments investigated decompose during the heating and originate pyrolysis products whose evolution is monitored continuously by the FT-IR spectrometer
Observations of the Energy Spectrum in the Mid-Infrared Region at Ambient Temperatures
Authors: Azarraga L. V. , Brackett J. M. , Castles M. A. , Rogers L. B.
Published: July 2005

A technique for the obtaining of the energy signal and, thus, the IR spectra is described The technique is simple and sensitive and allows the observation of high frequency vibrational bands The technique utilizes a silver bromide disc as a sample holder set in a diffuse reflectance attachment Spectra of o-nitroaniline 1-tetra-decanol, and copper phthalocyanine green are presented Possible applications of the technique include compound identification and FT-IR analysis of HPLC effluent
Laser-Induced Intermodulated Flame Fluorescence: A New Approach to Scattering Correction in Analytical Atomic Fluorescence
Authors: Omenetto N. , Hart L. P. , Winefordner J. D.
Published: July 2005

It is shown that the technique of intermodulated fluorescence can effectively correct for scattering problems in analytical flame fluorescence spectroscopy. When two laser beams, amplitude-modulated at different frequencies f1 and f2 and counterpropagated colinearly throughout an atomizer, are tuned to the absorption transition of the element of interest, non-linear mixing of the fluorescence signal results, due to saturation effects. By extraction of the signal at the sum or difference frequency, f2 ± f2, the linear scattering component of the spectrum can be essentially eliminated. This has been demonstrated for a sodium solution nebulized in a premixed, laminar, argon-oxygen-hydrogen flame. Because the modulation signal can be observed only at the intersection volume between the two beams, this technique constitutes a powerful tool for spatially resolved combustion diagnostics.
Simultaneous Multicomponent Quantitative Analysis by Infrared Absorption Spectroscopy
Authors: Tyson Lesia L. , Ling Yong-Chien , Mann Charles K.
Published: July 2005

Two data-handling techniques, least-squares fitting and cross-correlation, have been used for three-component analysis under comparable conditions with the use of both simulated and real data Factors considered are the effect of variation in degree of peak overlap, signal-to-noise ratio, the effect of peak width variations when peak maxima occur at the same position, and the effect of varying peak intensities A series of lipid mixtures was analyzed by each method with the use of infrared absorption This permits comparison of these results with earlier reports Both least-squares and cross-correlation can be used with samples that are outside the applicable range of the earlier work In this comparison, the least-squares results are somewhat better than those from cross-correlation
Analysis of Multi-Component Gas Mixtures by Correlation of Infrared Spectra
Authors: Bingham D , Burton C. H.
Published: July 2005

A simulation study and an experimental investigation of the effect of noise and resolution in the determination of polar gas pressures in gas mixtures has been performed The pressures were obtained by a procedure which correlates the polar gas infrared spectra and describes band absorptance phenomenologically For single-polar-component binary mixtures, the partial pressure may be found accurately over a wide range of resolution Low resolving powers are favored with noisy spectra Polar gas partial pressures were also extracted from quaternary mixtures, with an uncertaintity of less than 5% over a wide range of resolving power Improvements to and limitations of the technique are discussed
Theoretical Aspects and Design of a Low-Power, Low-Flow-Rate Torch in Inductively Coupled Plasma Atomic Emission Spectroscopy
Authors: Angleys G , Mermet J. M.
Published: July 2005

Based on a previously published work, calculations of the minimum plasma gas flow rate for torch tubes of various dimensions have been performed Predicted minimum rates have been verified by experiment It is possible to sustain a discharge at 600 W and 6 L/min without reducing drastically the external size of the torch One of the main parameters in torch design is the various flow velocities The main influence on the plasma gas flow rate is provided by the space between the external and the intermediate tube A practical design is proposed and a comparison is made with the literature
Infrared Spectrophotometric Determination of 13C Enrichment
Authors: Tyson Lesia L. , Vickers Thomas J. , Mann Charles K.
Published: July 2005

A study has been made of the feasibility of using the v3 band of 13C2 as a basis for measurement of the extent of isotope enrichment in breath tests Correlation and least-squares treatments were used Considering the constraints of a small computer, the correlation approach is the more satisfactory The results indicate that a method that is based on a single measurement at 170 Torr, with a standard curve for quantitation, will give results that are adequate, considering the natural variation that occurs Assuming the use of a beam condenser, the amount of sample required is less than that normally taken for this application
Spectrochemical Analysis of Liquids Using the Laser Spark
Authors: Cremers David A. , Radziemski Leon J. , Loree Thomas R.
Published: July 2005

A laser-generated spark was used to analyze liquids spectroscopically for elemental constituents The spark was produced directly in liquids by a focused laser pulse of 15 ns duration and an energy of about 45 mJ/pulse The size, temperature, and electron density of the spark are reported Emissions from once-ionized and neutral atoms and simple molecules were observed Limits of detection for Li, Na, K, Rb, Cs, Be, Mg, Ca, B, and Al in aqueous solutions were established with the use of a 10 Hz repetitive single spark (RSS) Most of these elements were only detectable at levels above 1 µg/mL, although the detection limit for Li was 0006 µg/mL The relative standard deviation for replicate sample analysis was 4–8% The detectability of some species was enhanced with the use of a 10 Hz repetitive spark pair (RSP): a pair of sparks separated in time by about 18 µs The detection limits for B/H2O with the RSP and the RSS were 80 and 1200 µg/mL, respectively Species were also detected in organic solvents and in flowing samples The laser spark method of liquid analysis would be useful in situations requiring noninvasive monitoring of species at high or moderate concentrations
Coherent Anti-Stokes Raman Spectroscopy of Polycyclic Aromatic Hydrocarbons
Authors: van Hare D. R. , Carreira L. A. , Rogers L. B. , Azarraga L.
Published: July 2005

Coherent anti-Stokes Raman spectroscopy (CARS) was used to obtain Raman spectra of thirteen polycyclic aromatic hydrocarbons (PAHs) composed of between three and seven fused rings. The compounds were pumped in the resonance and preresonance regions to obtain the sensitivity necessary for examination at concentrations down to 1.5 × 10 −5 M. A simple mixture of three PAHs was optically separated through the wavelength selectivity of the resonant enhancement process. Comparisons between the spectra of the mixture and the spectrum of each pure component showed essentially no differences when pumped at the same wavelength. Finally, lineshape analysis was performed on the CARS spectra to facilitate comparisons between classes of compounds and for quantitative purposes.