bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Sampling Rate on Fourier Transform Spectra: Oversampling is Overrated
Authors: Alber George M. , Marshall Alan G.
Published: June 2005

In Fourier transform spectrometry, an analog time-domain signal is sampled at equally spaced intervals and subjected to a discrete Fourier transform to yield a discrete frequency-domain spectrum. Round-off errors in the sampling process can generate quantization “noise” even for a noiseless time-domain analog signal. Oversampling refers to sampling a time-domain analog signal at a rate faster than that required by the Nyquist limit. Oversampling has been applied in a wide variety of fields, including image, speech, and audio spectral analysis. It has been variously claimed that oversampling can increase the effective number of analog-to-digital converter (ADC) bits, increase signal-to-noise ratio and/or resolution, allow for improved phase and/or magnitude linearity, and reduce quantization “noise” in the bandwidth of interest. In this paper, we explain and demonstrate the effects of oversampling in Fourier transform spectrometry. For Fourier transform interferometry, magnetic resonance, or ion cyclotron resonance mass spectrometry conducted with an ADC of at least 12 bit/word, we conclude that quantization “noise” is negligible; oversampling thus has little effect on FT spectral signal-to-noise ratio, dynamic range, or resolution. Oversampling can, however, improve phase and magnitude linearity by eliminating the need for a sharp cutoff in the passband of the analog filter. Finally, autocorrelation analysis of simulated time-domain signals shows that quantization “noise” is random and essentially independent of frequency (i.e., “white”) at practically attainable sampling rates.
Fiber Structure Study by Polarized Infrared Attenuated Total Reflection Spectroscopy: Orientation Development of Nylon 66 at Various Spinning Speeds
Authors: Samanta S. R. , Lanier W. W. , Miller R. W. , Gibson M. E.
Published: June 2005

It has been shown that the use of a polarized attenuated total reflectance (ATR) infrared technique affords a means to study structure/frequency relationships and orientational behavior in partially oriented nylon (PON) yarns. In continuing studies, efforts have been directed toward the study of orientational development in the high-speed spinning of high-viscosity (HV) and low-viscosity (LV) Nylon 66 yarns. Infrared dichroism was used to study fiber orientation, and a relationship between infrared dichroism and orientation factor has been developed. The relationship between orientation measured by infrared and by x-ray diffraction is also shown. These are used to obtain the transition moment direction of a molecular vibration, which would otherwise be impossible to obtain by a single technique. Transition moment angles determined for crystalline vibrations were 39° and 41° with respect to the molecular chain axis for high- and low-viscosity PONs, respectively. Crystalline orientation factors obtained with these values are in excellent agreement with x-ray results. Infrared data indicate a sharp increase in crystalline orientation at slower spinning speeds up to a point (transition point); then orientation increases monotonically with increasing speeds. Beyond the transition point, high-viscosity yarn showed less orientation; below this point it showed higher orientation than lower-viscosity yarn. This transition is interpreted to be related to the molecular relaxation phenomenon. Amorphous orientation was also estimated from the fIR and birefringence data, following the relationship proposed by Samuels. It was found that amorphous orientation was less than crystalline orientation at all speeds and practically insignificant at slower speeds, which leads us to the conclusion that, at low-to-moderate spinning speed, crystalline orientation predominates.
A Solution to Baseline Uncertainty Due to MCT Detector Nonlinearity in FT-IR
Authors: Carter R. O. , Lindsay N. E. , Beduhn D.
Published: June 2005

High-sensitivity mercury-cadmium-teluride (MCT) detectors have generally been used in low-light experiments and where quantitation was not essential. These restrictions were commonly believed to be associated with the nonlinear response of the detectors due to intrinsic limitations of the detection process. Recent preamplifier and bias circuit designs have made significant gains in reducing and, in the case of the broadband MCTs, virtually eliminating the nonlinear character of these detectors in typical FT-IR applications. This improvement in performance in achieved through a change in detector biasing from constant current to constant voltage.
Automatic Spectral Database and Archive System for Optical Spectroscopy
Authors: Kraus D. J. , French R. H.
Published: June 2005

With the advent of computerized data acquisition in spectroscopy, it has become possible to acquire large quantities of data with relative ease. Without a convenient method for archiving and accessing the data at a later date, a number of the capabilities inherent in these systems are unrealized. We have developed a generalized archival system which automatically archives all raw data and generates a rapidly searchable database of text information and spectral data for all spectroscopic results covering the spectral regions from 30 nm to 1000 µun (3.3 × 105 to 10 cm−1). The system executes on a local area network (LAN) of personal computers and consists of a customized file-naming and comment convention that organizes data by research notebooks, an integrated data backup routine, and a spectral database system. The data backup and spectral database consist of two programs: (1) a DOS level copy routine to back up the system and data to an optical write once/read many (WORM) drive, and (2) a spectral database program written in the Lab Calc spectroscopy environment. Stored with each spectral library entry are searchable text fields of character data parsed from a standardized comment line which is entered prior to data acquisition. This system is used consistently with three different spectrophotometers, allowing all results to be treated equivalently for further numerical analysis.
Selection of Samples for Calibration in Near-Infrared Spectroscopy. Part II: Selection Based on Spectral Measurements
Authors: Isaksson Tomas , Næs Tormod
Published: June 2005

Two strategies for selection of samples based on spectral measurements on a large set of samples are tested and compared. A method based on cluster analysis appears to be the best. The same prediction results achieved with the whole calibration set of 114 samples were obtained with only 20 samples selected by this algorithm.
Effect of Solvent Polarity on the Fluorescence Emission Spectra of Select Five- and Six-Ring Pyrene Derivatives
Authors: Acree William E. , Zvaigzne Anita I. , Fetzer John C.
Published: June 2005

The fluorescence properties of dibenzo[def,p]chrysene, benzo[rst]pentaphene, and anthranthrene dissolved in eleven organic non-electrolyte solvents are reported. Measurements indicate that both dibenzo[def,p]chrysene and benzo[rst]pentaphene exhibit probe character, as evidenced by the selective enhancement of the intensity of vibronic band I relative to band II with increased solvent polarity. Emission ratios of anthranthrene remained nearly constant, irrespective of solvent polarity. These results, combined with previously reported data for ben-zo[ghi]perylene, benzo[a]pyrene, benzo[e]pyrene, and dibenzo[a,e]pyrene, are used to examine molecular structure-probe character correlations of select five- and six-ring pyrene derivatives.
Reversible Excited-State Transient Solvation in Binary Supercritical Fluids Revealed by Multifrequency Phase and Modulation Fluorescence
Authors: Betts Thomas A. , Bright Frank V.
Published: June 2005

Frequency-domain fluorescence spectroscopy is used to study the transient solvation of 4-amino-N-methylphthalimide (4AMP) in binary supercritical fluids composed of 2-propanol and CO2. The time-resolved emission spectra are constructed for this system with the use of the wavelength-dependent frequency-domain data. Analysis of the experimental data indicates that: (1) 4AMP is pre-associated with 2-propanol prior to excitation; (2) the 2-propanol-induced spectral relaxation occurs on a nanosecond time scale; and (3) the excited-state reaction between 4AMP and 2-propanol is reversible.
Camera-Ready Copy for Papers to Be Published in Applied Spectroscopy: An Alternative Opinion
Authors: Goode Scott R.
Published: June 2005

Standards for preparation of camera-ready copy for articles submitted to Applied Spectroscopy need not follow exactly the stylistic conventions used by the journal. A simpler set of guidelines that can be easily implemented on most microcomputers is proposed.
Prism Coupling into Polymer Integrated Optical Waveguides with Liquid Superstrates
Authors: Saavedra S. S. , Reichert W. M.
Published: June 2005

We have investigated the light coupling behavior of prism-coupled waveguides adjacent to liquid superstrates. A flow cell was used for delivering the liquid superstrates to the waveguide surface. The incoupled angles and outcoupled mode patterns were collected from polystyrene waveguides subjected to superstrates of air, water, and dimethylsulfoxide. Results showed that poor coupling and significant mode scrambling were observed when liquids were infused into the flow cell volume. The poor waveguiding characteristics were found to be caused by the presence of air in the prism coupling gaps. Poor coupling was eliminated for a water superstrate by ensuring that water also occupied the prism coupling gaps. The mode coupled into the water-coupled waveguide with a water superstrate was always the most intense mode in the outcoupled pattern. In this manner it was shown that a refractive index mismatch between the coupling gap and the superstrate will lead to a waveguide with measured coupling angles that are completely insensitive to changes in superstrate refractive index.
Isotope Ratio Biases in Resonance Ionization Mass Spectroscopy Due to Population Trapping
Authors: Whitten W. B. , Ramsey J. M.
Published: June 2005

Population trapping via hyperfine ground-state coherences is proposed as a potential source of isotope ratio bias in resonance ionization mass spectra with coherent excitation of the first transition. Sample calculations are presented for a model 4-leveI Doppler-broadened system and qualitatively verified by experimental fluorescence excitation measurements.
A Novel Detector for Gas Chromatography Based on UV Laser-Produced Microplasmas
Authors: Morris Jeffrey B. , Forch Brad E. , Miziolek Andrzej W.
Published: June 2005

The use of UV laser-produced microplasmas for the detection of analyte molecules in the effluent gases of a gas chromatograph is described. The microplasmas are formed when a carbon-containing analyte is present in the carrier gas flow but not in the carrier gas alone. The microplasmas are produced by using the 193-nm output of the ArF excimer laser, with only modest pulse energies (10 mJ) required. Three means for detecting the presence of the microplasmas have been effected and are compared: optogalvanic (plasma electron) detection, photoacoustic (blast wave) detection, and photometric (plasma emission) detection, particularly of electronically excited carbon atoms at 248 nm. The relative responses of these three techniques have been determined for microliter injection of acetylene into the helium flow. Present limits for acetylene with the use of the optogalvanic, photoacoustic, and photometric techniques are 500, 500, and 10 ng, respectively. Optimization of these techniques is expected to improve the detection limits by 2–4 orders of magnitude. The virtues of this detector include the fact that it requires no flame and that it is sensitive to carbon-containing species such as CO and CO2.
Camera-Ready Copy for Papers to Be Published in Applied Spectroscopy
Authors: Scheeline Alexander , Bohn Paul W. , Goode Scott R. , Coleman David M. , de Haseth James
Published: June 2005

Standards for preparation of camera-ready copy for articles submitted to Applied Spectroscopy are presented.
A Moderate-Power Nitrogen Microwave-Induced Plasma as an Alternative Ion Source for Mass Spectrometry
Authors: Shen Wei-Lung , Davidson Timothy M. , Creed John T. , Caruso Joseph A.
Published: June 2005

The moderate-power nitrogen plasma is evaluated as an alternative ion source for plasma mass spectrometry. The nitrogen MIP-MS exhibits linear dynamic ranges of about 3–4 orders of magnitude and low ppb to sub-ppb detection limits for most elements under multielement scanning conditions. Nitrogen MIP-MS is capable of determining K, Ca, Cr, As, and Se at their major isotopes. In addition, nitrogen MIP-MS provides lower detection limits than argon ICP-MS for K (0.48 ppb) and Ca (0.24 ppb). The nitrogen MIP-MS system allows the determination of isotope ratios for 10 ppm of Ca (40/44) and 100 ppb of K (39/41), Cr (52/53), and Se (80/78) with less than 5% error.
EXAFS Smoothline Determination Using Splines: Finding the Optimal Smoothline and Fast Computation
Authors: Proctor A. , Fay M. J. , Hoffmann D. P. , Hercules D. M.
Published: June 2005

The feasibility of the PC IMSL cubic spline smoothing routine CSSMH (ICSSCU in the mainframe edition) for numerical determination of the EXAFS smoothline ( μo) is discussed. Examination of the cubic spline algorithm employed suggests that a relatively simple coding modification results in a considerably more efficient algorithm for use in EXAFS. The rudimentatary code already exists in the literature. This allows incorporation of the modified code into current programs without the large memory overhead necessary when IMSL is being used. The degree of flexibility is determined by a parameter which can have values in the range 0 to 1. The EXAFS smoothline requires that the algorithm be used at one extreme end of this range of flexibility. At the other end of this range the routine can be used for interpolation. A suggested path for finding the optimal smoothline, based on the use of coarse and fine smoothing parameters, is discussed.
Analysis of Antioxidants in Polyethylene Using Supercritical Fluid Extraction/Supercritical Fluid Chromatography and Infrared Detection
Authors: Wieboldt R. C. , Kempfert K. D. , Dalrymple D. L.
Published: June 2005

Supercritical fluid extraction using 100% carbon dioxide is able to remove antioxidant additives from flaked polyethylene. SFE appears to be more selective for the lower-range low-MW polymer than Soxhlet-type extraction. This yields a chromatogram with less interference from low-MW polymer peaks in the region where the additive components elute. Infrared detection is able to locate peaks corresponding to distinct types of additives by generating chromatograms from chemically specific regions of the SFC/IR data. Infrared spectra are sufficient for identification of additives and determination of the oxidation state of phosphorus-containing antioxidants.
Nonlinearity of Calibration Graphs for Laser-Excited Atomic Fluorescence in Graphite-Tube Atomizers
Authors: Dougherty Joseph P. , Preli Francis R. , Wei Guor-Tzo , Michel Robert G.
Published: June 2005

Calibration graphs for Laser-Excited Atomic Fluorescence Spectrometry (LEAFS) were constructed for graphite-tube electrothermal atomizers (ETAs). Laser radiation was propagated through holes in the side of the tubes, and atomic fluorescence was detected at a right angle through the bore of the tube. The LEAFS calibration graphs, while linear with a relative slope of one for 4 to 6 orders of magnitude, became nonlinear at high analyte concentrations. Observations concerning this nonlinearity are presented here. The onset of nonlinearity was believed to be primarily caused by post-filter effects. For nonresonance LEAFS, long lifetimes for the terminating energy levels in the fluorescence processes were believed to increase the probability of post-filter effects and subsequently to increase curvature of calibration graphs. Those conditions that increased the residence time of atoms in the furnaces (i.e., no internal gas flow and platform atomization) appeared to also increase post-filter effects and thus increased the amount of curvature of the calibration graphs.
Background Spectral Features for Moderate-Power Nitrogen Microwave-Induced Plasma-Mass Spectrometry
Authors: Shen Wei-Lung , Davidson Timothy M. , Creed John T. , Caruso Joseph A.
Published: June 2005

The mass spectral background features of a moderate-power nitrogen microwave-induced plasma are presented. In general, the mass spectral background obtained from a nitrogen plasma is less congested at low mass than is the case with argon ICP-MS. In addition, there are no significant (less than 20 counts per second) background species above mass 60. At normal multiplier voltage, the major background species found in a dry nitrogen plasma include 14N+, 14NH+, 14N2+, 14N2H+, 14N16O+, 14N16OH+, 14N3+ and 14N4+. This background is unchanged by the nebulization of deionized water, 5% (v/v) acids (nitric, hydrochloric, and sulfuric acids), and 5% (v/v) methanol solutions. These background species do not interfere with the determination of K, Ca, and Se at their major isotopes, which commonly have interfering background species in Ar ICP-MS. On the basis of the nebulization of 5% HCl and methanol in the nitrogen plasma, As and Cr do not have isobaric interferences at their major isotope masses 75 and 52. In addition, preliminary studies on the effect of Na as a concomitant element on analyte signals indicate severe enhancement or suppression of analyte signals.
Optical Spectroscopy for the Characterization of an Alloy Steel Converting Process
Authors: Wendt Wilhelm , Persson Willy
Published: June 2005

The light emitted by the off-gases of a CLU converter for alloy steel production has been spectroscopically investigated. The observations were made on-line with the use of an optical multichannel detection technique. In addition to the continuous heat radiation, emission from a large number of atoms and molecules was observed.
Liquid Analysis by Dry-Extract Near-Infrared Reflectance on Fiberglass
Authors: Alfaro G. , Meurens M. , Birth G. S.
Published: June 2005

Nonvolatile residues of liquid samples were retained on fiberglass filters, and near-infrared reflectance spectroscopy was used for a rapid nondestructive analysis of the residue. However, neither log(1/R) nor (1 – R)2/2 R computations gave results that varied in a linear manner with solute concentration. Nonlinear curve fitting of experimental data to a mathematical model [log 1/ R = h + s(1 – exp(– kC))] has shown a good correlation with the model. On the other hand, NIR analysis by multiple linear regression has been evaluated for rapid determination of both total and individual sugars in aqueous solutions containing glucose, fructose, and sucrose mixtures. The concentration ranges of glucose, fructose, and sucrose are, respectively, 20–50 g/L, 20–50 g/L, and 0–50 g/L. Standard errors of performance for prediction are 1.8 g/L for sucrose, 3.5 g/L for glucose, 3.0 g/L for fructose, and 5.3 g/L for total sugars (range 0–150 g/L). The results of this study show its potential application in beverage analysis (fruit juices, lemonade) and other liquid systems.
Studies of Chemically Modified Poly(Ethylene Terephthalate) Fibers by FT-IR Photoacoustic Spectroscopy and X-Ray Photoelectron Spectroscopy
Authors: Yang Charles Q. , Bresee Randall R. , Fateley William G.
Published: June 2005

Fourier transform infrared photoacoustic spectroscopy (FT-IR/PAS) and x-ray photoelectron spectroscopy (XPS) were used to determine the location of a copolymeric finish in poly(ethylene terephthalate) (PET) fibers. The XPS studies showed that the copolymeric finish was deposited on the fiber surfaces. The FT-IR/PAS data demonstrated possible penetration of the finish from the fiber's surface into the near-surface. The combination of FT-IR/PAS and XPS appears to be very useful for the determination of finish location in chemically modified fibers.
Urinary Stone Analysis by Small-Spot Electron Spectroscopy for Chemical Analysis (ESCA)
Authors: Campbell A. A. , Gardella J. A. , Richardson C. F. , Nancollas G. H. , Siordia R. A.
Published: June 2005

Small-spot Electron Spectroscopy for Chemical Analysis (ESCA) has been used to study the composition of calcium oxalate and calcium phosphate urinary stones. This technique allows for the identification and location of various inorganic and organic species and provides information about the events leading to stone formation. Unlike other methods, such as scanning electron microscopy and x-ray diffraction, which provide elemental composition and morphological information, ESCA, with its high sensitivity for low Z elements, is also able to detect differences in chemical functionality. The spectra obtained from a urinary stone cross section show changes in chemical composition and functionality of carbon and nitrogen species. Comparison of these spectra with those of standard reference materials has enabled the identification of each detected species.
Temporal and Spectral Characteristics of the Output of an Excimer Laser
Authors: Johnson Mitchell E. , Voigtman Edward
Published: June 2005

The output of a Questek Model 2210 excimer laser, operated with XeCl fill, is characterized in both the time and frequency domains. Power spectra are obtained through use of the fast Fourier transform which show that the output is essentially white in character. Furthermore, noise power diminishes with repetition rate, reaching a broad minimum around 40 Hz. Analysis in the time domain shows a “roughly Gaussian” distribution. Movement of optically opaque (“thick”) particles in the path of the laser beam is shown to increase the variance of the noise, but not its low-frequency content.
Thickness-Dependent Frequency Shift in Infrared Spectral Absorbance of Silicon Oxide Film on Silicon
Authors: Gunde Marta Klanjšek , Aleksandrov Boris
Published: June 2005

The spectral dependence of the refractive index n and extinction coefficient k of chemical-vapor-deposited (CVD) silicon oxide film on silicon wafer has been determined. The results are used to calculate spectral absorbances for 0.1–2 μm thick oxide films with unchanged structure. The dependence on thickness of the position of Si-O stretching ( vM) has been investigated. The main factor influencing the frequency is the transmission factor at the air/film and film/substrate boundaries. In the limit of d → 0, vM corresponds to the maximum of the Im (ε) function.
Capacitive-Discharge Circuit for Controlled Heating of Anisotropic Graphite Tubes. Part II: Characterization for Graphite Furnace Atomic Absorption
Authors: McCaffrey John T. , Michel Robert G.
Published: June 2005

Performance data from a recently described capacitive-discharge heating system are presented. The capacitive-discharge heating circuit, which used a 0.15 F capacitor bank, is shown to provide reproducible heating of a small anisotropic graphite tube (5 mm o.d. × 9 mm long, 1 mm wall thickness) at heating rates of up to 65°C per ms to a final temperature of 2500°C. The performance and resistance of graphite from two manufacturers are compared. The effect of the capacitor bank voltage on the heating rate and maximum achievable temperature is studied. Photographic and optical pyrometric evidence of the circumferential temperature anisotropy is presented. Pyrolytically coated anisotropic graphite tubes were investigated. Preliminary investigations using Pb indicated that sample deposition on the unbroken lamellar graphitic planes provides about 1.5 times the peak-area and peak-height sensitivity obtained from sample deposition across the lamellar planes.
Topical Protectant Evaluation by FT-IR Spectroscopy
Authors: Braue Ernest H. , Pannella Michael G.
Published: June 2005

A unique analytical method for evaluating the effectiveness of topical protectants against penetration by chemical agents has been developed with the use of FT-IR and the horizontal attenuated total reflectance (ATR) accessory. A template was designed which allowed a uniform-thickness layer of topical protectant to be applied to the surface of the ATR crystal. A chemical challenge was applied to the template filled with topical protectant, and spectra were recorded with the use of standard GC software on a Nicolet 60SXB FT-IR spectrometer fitted with an MCT-A detector. Analysis of the recorded spectra identified how much time was required for the chemical challenge to break through the topical protectant barrier. The method was validated with the use of polysaturated fat, petroleum jelly, and hexafluoropropylene epoxide polymer as topical protectants. These materials were challenged with liquid ethyl disulfide. The detection threshold concentration for ethyl disulfide in the topical protectant was observed to be 0.5% (w/w). With a barrier thickness of 0.45 mm, the breakthrough times were observed to be 5.0 min and 22.0 min for polysaturated fat and petroleum jelly. The fluoropolymer showed no breakthrough after 60 min.
Solution Infrared Spectra of Cellulose Acetate Butyrate
Authors: Saunders C. William , Taylor Larry T.
Published: June 2005

The solution infrared spectra of cellulose acetate butyrates (CABs) have been collected in three solvents. The relative merits of each solvent are presented with regard to the spectral information obtained about CAB. In addition, correlations between absorbances at 1235 cm−1 and 1176 cm−1 in acetonitrile and the acetyl and butyryl content of the CAB have been developed.
Mirror-Coated Long-Path Cells for Colorimetry with the Use of a Bifurcated Optical Guide
Authors: Fujiwara Kitao , Nakamura Toshihiro , Kashima Toshiyuki , Tsubota Hiroyuki , Solin Taka-Aki , Aihara Masato , Kiboku Mitsuo
Published: June 2005

For sensitive measurement of the absorbance of aqueous solution, mirror-coated long-path cells have been constructed, in which introduction of light from a laser diode and collection of the reflected light passing through the analyte solution are done through the same end of the cells with the use of a bifurcated fiber. The absorbance of the solution has been enhanced about 20 to 30 times by using the present system. Also, the present mirror-coated long-path cells show a sharp response in turbidity with respect to the change toward smaller particle sizes in Latex gel. The present detection system has been coupled with the flow injection analysis of phosphate in molybdenum blue colorimetry. Detection of phosphate at 1 ng P/mL is possible with this measurement system—a result which is rather difficult to achieve with the use of a commercial auto-detection system.
Thermal Lens-Circular Dichroism Spectropolarimeter
Authors: Xu Minren , Tran Chieu D.
Published: June 2005

A novel, ultrasensitive thermal lens-circular dichroism spectropolarimeter (TL-CD) has been developed. In this instrument, a chiral sample is sequentially excited by the left circularly polarized laser light (LCPL) and right circularly polarized laser light (RCPL); both of these excitation beams are derived from the same argon ion laser. The heat generated as a consequence of the sample absorption of the LCPL and RCPL is measured by the probe laser beam collinearly overlapping with the two excitation beams. The TL-CD signal corresponds to the difference in the thermal lens signals produced by the LCPL and the RCPL excitation beams. Compared to characteristics of the conventional spectropolarimeters, the advantages of this TL-CD apparatus include its higher sensitivity, small volume capability, and wider applicability. A detection limit of 5 ng of optically active [Co(en)]3+ complexes whose volume was as small as 8 μL has been estimated for this apparatus with the use of 37 mW excitation power modulated at 1.1 Hz.
Drug Retention during Animal Inhalation Exposure by FT-IR Spectroscopy
Authors: Braue Ernest H. , Pannella Michael G.
Published: June 2005

A unique analytical method for the determination of the amount of volatile drug retention by animals during inhalation exposure experiments was developed and evaluated. A large-volume collection system was used to collect and store all exhaled air from the animal. The collected air was analyzed by FT-IR spectroscopy with the use of a Nicolet 5SXB spectrometer and a Spectra-Tech Inc. 10-m long-path gas cell. The developed technique was evaluated with the use of bis-(trifluoromethyl) disulfide (TFD) administered to adult sheep. Control experiments confirmed the system's ability to capture 100% of the administered compound. It was observed that the sheep retained an average of 4.4 mg of this compound per kg of body weight during a 10-min exposure period at an air concentration of 5.0 mg per L. After quantitative analysis, compounds exhaled by the animal were concentrated by passing the collected air through a series of dry-ice and liquid-nitrogen-cooled traps. FT-IR analysis of the collected concentrated products indicated that TFD did not undergo chemical decomposition to form trifluoromethyl sulfide during the exposure experiment. The exposure system and the analytical method developed can be used with both large and small animals.
Simulated Supercritical Fluid Chromatography Mobile Phase Introduction to a Helium Microwave-Induced Plasma: Effects on Nonmetal Emission and Spectral Behavior
Authors: Webster Gregory K. , Carnahan Jon W.
Published: June 2005

The effects of the introduction of capillary supercritical fluid chromatography mobile phases, CO2 and N2O, into a helium microwave-induced plasma (He-MIP) are investigated. The plasma and mobile-phase flow rates are maintained at conditions comparable to those typically used for these systems. Spectral characteristics are monitored in both the ultraviolet-visible and near-infrared regions. Molecular bands from these “foreign” gases are assigned and their relative intensities are noted as a function of the doping gas flow rate. Possible molecular band interferences are noted for nonmetal atomic emission determinations with He-MIPs. Nonmetal atomic emission reduction by these gases is studied with the use of chlorine atom and ion lines as test signals. Decreases in chlorine atom and ion emission are seen as CO2 and N2O flow rates are increased. It is found that ion line emission intensity is reduced more significantly than atom line emission. Reduction of both atom and ion line emission is more pronounced with CO2 than with N2O. The electron density of the plasma does not change as the CO2 flow rate is increased from 0 to 0.25 mL (STP)/min.
Principal Component Analysis of Trace Elements from EDXRF Studies
Authors: Yap C. T. , Vijayakumar V.
Published: June 2005

With the use of the EDXRF technique, the concentrations of 14 trace elements (Mn, Fe, Co, Ni, Cu, Zn, Ga, As, Rb, Sr, Y, Zr, Nb, and Mo) of Japanese pottery samples from three different regions were measured. Principal component analysis shows the possibility of discriminating between the various trace elements in terms of their being either useful or not useful variables by which Japanese pottery samples could be grouped according to their geographical origin.
Near-Infrared Reflectance Analysis of Carbonate Concentration in Soils
Authors: Ben-Dor E. , Banin A.
Published: June 2005

A group of 91 soils from arid-zone regions were used to develop a nondestructive near-infrared analysis (NIRA) procedure for estimating carbonate concentration in soils. Carbonate concentration was measured gasometrically and reflectance in the NIR was measured by a high-resolution FT-NIR instrument. The reflectance data were converted to absorption and derivatized, and statistical procedures were applied to obtain the multivariate regression equation between the various manipulated optical data and carbonate concentration. Reflectance from preheated (600°C) and nonheated soils was compared to test the ability to remove spectral interferences caused by hydroxyl groups. Forty-three soils were used for calibration, and subsets were selected by different strategies which either maximized variation of soil properties (as measured by their specific surface area) in the selected set, or minimized it. A validation set of 48 soils was used to test the prediction-ability of the various calibration equations obtained. Most of the wavelengths entered into the calibration equations were spectroscopically explainable as belonging to carbonate absorption features. Satisfactory prediction was obtained, however, in only one combination of conditions (heated soils; 21 samples in calibration set; second derivative of absorption). Standard error of prediction (SEP) was similar to standard error of calibration (SEC) in this case (7.9% and 5.9%, respectively) if 7 samples belonging to one soil type (Xerochrept) were omitted from the validation set. We conclude that carbonate in soils in the concentration range of 10 to 75% can be satisfactorily estimated for pedological and soil classification purposes by the rapid and nondestructive NIRA procedures.
Quantitation of Mercury in Petroleum by ETV-ICP-MS
Authors: Osborne Stephen P.
Published: June 2005

A technique for quantitating soluble and suspended mercurials in petroleum was evaluated as potentially useful for the analysis and screening of crudes and napthas. Crudes and napthas can contain hazardous concentrations of mercury capable of causing the embrittlement of aluminum piping and heat exchange equipment. Electro-Thermal Vaporization (ETV) was used to atomize the sample at 2650°C. The aerosol of this untreated sample was channeled via an argon gas stream into an Inductively Coupled Plasma-Mass Spectrometer (ICP-MS). The study centers on the alkanes ranging from pentane (C5) to dotriacontane (C32) and reveals trends relevant to the analysis of mixed nonpolar unknowns. The system produces useful sensitivities in the range of C5 to C14 with a detection limit of 3 (±50%) parts per billion in pentane. For carbon mixtures above C14 there was advanced equipment wear and suppression of the analytical signal. This suppression is attributed to changes in the sample transport efficiency and destabilization of the plasma due to a greater energy release for the longer chains. The formation efficiencies of the monovalent ion were considered, and several compounds were investigated. No statistical difference between the burning of diethyldithiocarbamate mercury (DEDTC Hg as found in Conostan standards) and elemental mercury as standards was found.
Vacuum Ultraviolet Inductively Coupled Plasma Spectroscopy for Element-Selective Detection of Nonmetals
Authors: Denton M. Bonner , Pilon Michael J. , Babis Jeffery S.
Published: June 2005

Use of an inductively coupled plasma for elemental analysis of many organic compounds has been limited by the inability to provide sensitive analysis for a variety of nonmetallic elements. Data presented in this manuscript demonstrate detection limits and working curves showing usable dynamic ranges for oxygen, nitrogen, chlorine, and bromine in the vacuum ultraviolet region. The use of inductively coupled plasma as an element-selective gas-chromatographic detector is also investigated.
Single-Crystal Raman Studies on the Solid Hydrates MX2·H2O (M = Ba, Sr; X = OH, Br, I)
Authors: Henning J. , Beckenkamp K. , Lutz H. D.
Published: June 2005

Single-crystal Raman spectra of the isomorphic orthorhombic halides MX2·H2O ( M = Sr, Ba; X = Br, I) and hydroxides M(OH)2·H2O (Sr(OH)2·H2O and β-Ba(OH)2·H2O) are presented. Unambiguous assignment of the wagging, twisting, and rocking librations of the water molecules and the librational modes of the OH− ions is established. On the basis of both the H/D isotopic shifts and the intensities of the Raman bands, separation of the translational modes with respect to pure H2O (and OH−) vibrations and other lattice modes is likewise possible. Unit cell group (and TO/LO) splittings of internal and external modes as well as the sequences of the water bands in terms of both energy and intensity are discussed with regard to the crystal structures, especially the intramolecular and intermolecular symmetry of the water molecules. An improved procedure of suppressing refraction and stray-light effects and recording Raman spectra of crystals as small as 0.01 mm in diameter is given.
X-Ray Fluorescence Calibration with Partial Least-Squares
Authors: Wang Yongdong , Zhao Xinna , Kowalski Bruce R.
Published: June 2005

X-ray fluorescence (XRF) spectrometry is a popular method for noninvasive elemental analysis of a wide variety of sample types. Unfortunately, applications of XRF are complicated by the occurrence of interelement effects, which make the measured intensities complex functions of multiple-element concentrations. In this work, an implicit modeling method, partial least-squares (PLS), was used to correct for interelement effects in x-ray fluorescence analysis. Instead of fitting XRF peak intensities and concentrations to classical explicit models, the XRF spectra of a set of standard samples were used to build PLS models, implicitly relating the XRF spectra to the concentrations. Methods for the pretreatment of spectra are compared for a set of nickel alloy samples containing Fe, Cr, Ni, Mn, Mo, Ti, and Si. The PLS calibration method using appropriately preprocessed spectra gives the best results, when compared to the results from the literature and from a conventional explicit calibration model (MLR method).
Polycyclic Aromatic Hydrocarbons and Polycyclic Aromatic Sulfur Heterocycles: Examination of Molecular Structure-Fluorescence Probe Character Correlations
Authors: Acree William E. , Tucker Sheryl A. , Cretella Lisa E. , Zvaigzne Anita I. , Street Kenneth W. , Fetzer John C. , Nakasuji Kazuhiro , Murata Ichiro
Published: June 2005

Fluorescence emission spectra are reported for 1,6-dithiapyrene, 3,10-dithiaperylene, 1,7-dithiaperylene, thianthrene, benz[4,10]anthra-[1,9,8abcd]coronene, and benzo[cd]chryseno [4,5,6,7fghijk] perylene dissolved in several nonelectrolyte solvents of varying polarity. Emission spectra of the four polycyclic aromatic sulfur heterocycles (PASHs) contained very little fine structure. Severe spectral distortion, along with significant band broadening, was often observed in the case of PASHs dissolved in polar solvents. Benz[4,10]anthra[1,9,8abcd]coronene showed some probe-like character as evidenced by selective emission intensity enhancement of band I in dimethyl sulfoxide as compared to n-hexadecane solvent. The ratio of emission intensities for benz[4,10]anthra-(1,9,8abcd]coronene, however, failed to vary systematically with solvent polarity. Results of these fluorescence measurements indicate that all six solutes are unsuitable for solvent polarity probes.
A Controlled-Environment Chamber for Atmospheric Chemistry Studies Using FT-IR Spectroscopy
Authors: Stone Daniel A.
Published: June 2005

A one-meter-diameter, Teflon®-coated, stainless steel sphere has been constructed as a tool for conducting studies of the atmospheric chemistry of toxic chemicals. The temperature can be controlled from 5 to 50°C. The chamber can be evacuated to 5 × 10−6 Torr. Gas samples can be introduced from an external manifold. Solid samples of various kinds can be placed into the interior of the chamber through a 12-in. sampling port to determine their effects on gases under study. The chamber is equipped with an in situ, multipass optical system which allows an infrared pathlength of 106 m to be used for the analysis of chemical species.
Benzene in Zeolite ZSM-5 Studied by Diffuse Reflectance Infrared Spectroscopy
Authors: Wang H. Paul , Yu T. , Garland Ben A. , Eyring Edward M.
Published: June 2005

The behavior of benzene molecules in ZSM-5 has been studied in detail with the use of diffuse reflectance FT-IR spectroscopy. The infrared difference spectra indicate that benzene molecules have a high selectivity for adsorption first on the most energetic (Brönsted acid) ZSM-5 sites. The existence of at least two adsorbed benzene species has also been confirmed by infrared spectroscopy. Deuterated benzene (C6D6) species located at the ZSM-5 channels and channel intersections are characterized by the C-D stretching vibrations at 2284 and 2276 cm−1, respectively. Since the high symmetry ( D6h) of the adsorbed benzene molecules is preserved, the framework of ZSM-5 may have been distorted. The distortion of the framework of ZSM-5 is also indicated by the red shift of the Si-O (or Al-O) asymmetric stretching vibrations (at ∼1215 cm−1) when adsorbed benzene molecules are present.
The Effect of Neon and Argon Additions on Improving Selectivities in the Helium Afterglow Discharge Detector
Authors: Zamzow D. , D'Silva A. P.
Published: June 2005

The ultraviolet (UV) spectra of the helium (He) afterglow and mixed gas helium-neon (He-Ne) and helium-argon (He-Ar) afterglows are presented. The effect of Ne and Ar on the He afterglow background spectrum and on the selectivities (versus carbon) for sulfur and phosphorus detection in the UV region is discussed.
An Ultraviolet Micro-Raman Spectrometer: Resonance Raman Spectroscopy within Single Living Cells
Authors: Sureau F. , Chinsky L. , Amirand C. , Ballini J. P. , Duquesne M. , Laigle A. , Turpin P. Y. , Vigny P.
Published: June 2005

Ultraviolet-excited resonance Raman spectra have been obtained for the first time for microsamples of dAMP deoxymononucleotide and DNA and for the nuclear DNA of a single living T47D cultured cell. The spectral variations observed in changing the excitation wavelength reflect the dramatic variations of the Raman cross sections of the various DNA compounds in the ultraviolet region. Many of the spectral features of the single-cell nuclear DNA excited by 257-nm radiation essentially arise from cellular purines, although a contribution from the protein amide I band and from the tryptophan residues is probably observed in the 1600–1700 cm−1 spectral region.
Optically Active Vibrations of Cesium Actinide(V) Hexafluorides (CsUF6, CsNpF6, and CsPuF6)
Authors: Ohwada Ken
Published: June 2005

Normal coordinate analysis of the optically active vibrations of CsUF6 has been made, with the assumption of an idealized structural model. On the basis of the results of this treatment, all of the observed bands so far reported have been successfully assigned to the intramolecular vibrations (UF6−) as well as the optically active lattice vibrations (the motions of Cs+ against UF6− octahedra, abbreviated to Cs+—UF6−). The force constants concerning U-F and Cs-F bonds have been obtained within the framework of the modified valence force field. These force constants have been transferred to predict fundamental vibrational frequencies of CsNpF6 and CsPuF6. It has been found that the present analysis based on a whole crystal is powerful not only for assigning the optically active lattice vibrations but also for elucidating the vibronic structures of the electronic absorption spectra obtained at low-temperature measurements.
The Applicability of a Multiple-Mode Diode Laser in Flame Atomic Absorption Spectroscopy
Authors: Ng Kin C. , Ali Abdalla H. , Barber Tye E. , Winefordner James D.
Published: June 2005

A multiple-mode laser diode is used to supply the primary radiation for atomic absorption spectroscopy (AAS). The multiple wavelength characteristics of the laser allow peak ratio measurements and possible background correction by the monitoring of the absorption spectrum with a diode-array spectrometer. In this demonstration, lithium is used as the analyte and air/acetylene flame is used as the atom reservoir. The detection sensitivity (1% absorption) is 20 ng/mL and the detection limit (2 σ of blank) is 4 ng/mL; these values are comparable to those of the conventional flame AAS with the use of a hollow cathode lamp as the source radiation.
On the Use of a Gauss Filter in the Deconvolution of Lorentzian Spectral Lines
Authors: Rex A. F.
Published: June 2005

It is well known that when the FIRO deconvolution method is used, maximum resolution enhancement results from self-deconvolution, e.g., when a Lorentz filter is used to deconvolute a mostly Lorentzian line shape [Applied Spectroscopy 35, 271 (1981)]. Unfortunately, self-deconvolution can also distort the line shape and introduce side lobes. In this paper it is shown that a Gauss filter can be used to deconvolute a Lorentzian line or lines and produce some resolution enhancement without significantly distorting the line shape or introducing other undesirable features.
Surface Modification of Polystyrene by Gamma-Radiation
Authors: Onyiriuka E. C. , Hersh L. S. , Hertl W.
Published: June 2005

The effect of gamma-radiation on the surface chemical properties of polystyrene was studied by ESCA and FT-IR. Gamma-radiation produces surface >C=O and C-O containing functional groups only, and also causes oxidation to depths >10 nm as detected by ESCA. FT-IR spectra showed that below the top few molecular layers ester, acid, and carbonyl groups of various types were present. The α,β-unsaturated carbonyl/acid groups form a higher proportion of the total carbonyls with increasing depth. Surface oxidation follows pseudo-first-order kinetics; the extent of interior oxidation is linear with dose.
Nondestructive Determination of the Composition of High-Tc Superconducting Thin Films
Authors: Cheng Jian-Bang , Zhao Yu-Zhen , Zhao Bai-Ru
Published: June 2005

The purpose of this paper is to describe two methods for composition determination of superconducting thin films: (1) the multiple standards method, in which a set of filter disks is used, and (2) the fundamental parameters method, in which only one standard is used. The two methods are convenient and easy to apply. The disk standards can be prepared readily. It is not necessary to destroy the samples to be determined. The methods are applied to superconducting thin films of an yttrium series; the principle of these methods can be applied to the films of other series as well. The methods can coordinate the process of scientific research and production quickly.
Characterization of Near-Infrared Atomic Emission from a Radio-Frequency Plasma for Selective Detection in Capillary Gas Chromatography
Authors: Skelton R. J. , Markides K. E. , Lee M. L. , Farnsworth P. B.
Published: June 2005

A radio-frequency plasma source has been characterized for use as an element-selective detector with capillary gas chromatography using atomic emission in the near-infrared region of the spectrum. With selected compounds introduced at rates similar to those encountered during a chromatographic run, the performance of the plasma has been characterized as a function of several interdependent variables, including plasma makeup gas flow, electrode spacing, and applied power. These settings have been optimized, and detection limits for several nonmetallic elements determined. Detection limits range from 0.2 to 50 pg/s.
Infrared and Raman Group Frequencies of Cyclic Imides
Authors: McKittrick P. T. , Katon J. E.
Published: June 2005

Infrared and Raman spectra of several examples of each of three classes of cyclic imides have been examined. Spectra-structure correlations have been sought for each of the classes, with particular emphasis being placed on the 1600–1800 cm−1 region. The spectra in this region are often complex, reflecting subtle structural features in the condensed phases. Group frequencies for substituted succinimides, phthalimides, and maleimides are proposed.
A Novel Infrared Spectrometer Using a Linear Array Detector
Authors: Richardson Hugh H. , Pabst Vernon W. , Butcher Jared A.
Published: June 2005

An infrared spectrometer has been constructed that employs a 32-element InSb linear array detector. A comparison has been made of the spectra obtained with this spectrometer with those obtained with a Fourier transform infrared spectrometer. It has been predicted that, from 2400 to 2650 cm−1 in the infrared spectrum, a four-microsecond transient could be captured with an approximate SNR of 50.