bluuebunny/crossref_metadata_2025 huggingface dataset:
Ion Kinetic Energy Determinations in Radio-Frequency Glow Discharge Mass Spectrometry
Authors: Cable Paula R. , Marcus R. Kenneth
Published: May 2005

Radio-frequency glow discharge (rf-GD) sources produce an abundance of both atoms and ions. For the mass spectrometric application of the glow discharge technique, knowledge of the ion kinetic energies is required to optimize extraction and focusing of ions from the source region into the analyzer. This paper details kinetic energies experimentally determined with the use of the “retarding potential” method. For this study, the analyzer quadrupole of a double-quadrupole mass spectrometer was positively biased to act as a repeller. Ion kinetic energies (IKEs) determined for a variety of discharge and analyzer operating conditions ranged from 12.5 eV to 25.0 eV for 63Cu+. Kinetic energy measurements were confirmed from ion trajectory simulations and follow closely the experimental values for identical analyzer conditions and initial IKEs. Results of this study indicate that the conditions under which ions are formed (plasma conditions) affect IKEs and energy spreads to a greater extent than analyzer parameter variations. Different from atmospheric plasma sources, IKEs for rf-GD species do not vary as a function of ion mass/identity. Evidence is also given in support of a slight mass biasing owing to the transmission properties of double-quadrupole analyzers. The findings detailed herein demonstrate the effects of rf modulation on both ion kinetic energy values and distributions.
Vapor-Phase Spectra and the Pressure-Temperature Dependence of Long-Chain Carboxylic Acids Studied by a CO Laser and the Photoacoustic Heat-Pipe Detector
Authors: Jalink Henk , Bicanic Dane , Franko Mladen , Bozóki Zoltán
Published: May 2005

A resonant photoacoustic heat-pipe (PAHP) cell was constructed and used for spectral studies of four long-chain saturated fatty acids (C10:0 to C16:0) at CO laser wavelengths and temperatures above that of the ambient. Vapor-phase absorption spectra were recorded at temperatures of 383 K for capric acid C10H20O2, 400 K for lauric acid C12H24O2, 438 K for myristic acid C14H28O2, and 445.5 K for palmitic acid C16H32O2, respectively. In addition, the temperature dependence (298 to 393 K) of vapor pressure was determined for C10:0; measurable PA signals were obtained at a temperature only a few degrees above the melting point for this acid. The data observed for C10:0 could be linearly fitted from as low as 323 K, indicating the validity of the Clausius-Clapeyron equation for temperatures lower than the 398 K < T < 541.4 K range anticipated so far.
Radio-Frequency-Powered Planar-Magnetron Glow Discharge as a Source for Time-of-Flight Elemental Mass Spectrometry
Authors: Heintz Mark J. , Myers David P. , Mahoney Patrick P. , Li Gangqiang , Hieftje Gary M.
Published: May 2005

A radio-frequency (rf) planar-magnetron glow discharge was investigated as an ion source for time-of-flight mass spectrometry. The first stage of a conventional ICP-MS interface was modified to create a planar-magnetron glow-discharge cell. The pressure and power of the magnetron source were optimized for ion signal. The perpendicular geometry of the mass spectrometer enables the relative energies of the extracted ions to be determined; the energies of the argon support gas and analyte ions were compared. The figures of merit for the system were investigated, and detection limits of 0.1–1 ppm were achieved for elements in a conducting matrix. Detection limits were an order of magnitude worse for elements in an electrically insulating sample. Along with an initial survey of the major spectral interferents, the relative sensitivities for different elements were determined. The source was also operated at low pressures (0.01 Torr) in order to determine whether operating in this pressure regime can be used to alleviate polyatomic interferences.
Cathodic Sputtering under High-Gas-Flow Jets
Authors: Zhu Zhubiao , Piepmeier Edward H.
Published: May 2005

Studies of cathodic sputtering with gas flow rates up to 2.13 L/min/jet were carried out in an Atomsource sputtering atomizer with Ar as the jet gas and Cu as the cathode sample. These flow rates are 20-fold greater than those normally used and were found to increase net sputtering yield significantly. A fourfold increase in net sputtering yield was observed when the number of jets in use was decreased from six to one, with the gas flow rate and other conditions held constant. Possible explanations for these effects are offered.
Laser-Induced Shock Wave Plasma in Glass and its Application to Elemental Analysis
Authors: Kurniawan H. , Nakajima S. , Batubara J. E. , Marpaung M. , Okamoto M. , Kagawa K.
Published: May 2005

The characteristics of a laser-induced shock wave plasma which was induced by focusing a laser pulse on the surface of glass samples were examined by using radiation from a XeCl excimer laser and a TEA CO2 laser under reduced pressure of around 1 Torr. It was observed that shock wave plasma could not be generated by the TEA CO2 laser on low-melting-point glass because of the lack of expulsion from the sample surface. On the other hand, with the use of an excimer laser, shock wave plasma can be generated, even in low-melting-point glasses, thus making it amenable for spectrochemical analysis. Initial quantitative analysis was performed on a number of glass samples, and a linear calibration curve with a slope of near unity was obtained at a certain pressure. Furthermore, light elements such as Li and B, which are usually difficult to observe by the X-ray fluorescence method, were also successfully detected with a very low detection limit of less than 10 ppm. Other detection limits and background equivalent concentrations of almost all elements usually contained in glass, such as Na, Mg, Al, K, Ca, Ti, Zn, Zr, and Ba, were also presented. These results showed that the detection limit is much lower than those usually required for glass analysis.
Monitoring the Acid-Catalyzed Hydrolysis of Starch with Near-Infrared Spectroscopy
Authors: Chung Hoeil , Arnold Mark A.
Published: May 2005

Results indicate that sufficient information is present in near-infrared (near-IR) spectra covering the range from 5000 to 4000 cm−1 to monitor the acid-catalyzed hydrolysis (thinning) of starch. Spectra taken from the aqueous fraction of samples collected during actual thinning reactions display information corresponding to soluble carbohydrates. The observed absorbance bands increase in magnitude according to the extent of the thinning reaction. A digital Fourier filter is applied to isolate the carbohydrate band centered at 4400 cm−1. This filtering step effectively removes choppy noise from the raw absorbance spectra and improves the measurement reproducibility by 3.6-fold. A third-order polynomial is used to empirically relate the integrated area under this 4400-cm−1 absorption band to the extent of starch thinning as measured as fluidity of the resulting starch paste. This model is able to accurately predict fluidities with an overall standard error of prediction of 1.94 mL for fluidity values ranging from 22 to 67 mL.
FT-IR/ATR Analysis of the Silicon/Aqueous Solution Interface Using Sputtered Silicon Thin Films to Access the 1550–1100 cm−1 Spectral Region
Authors: Sperline Roger P. , Jeon Joong S. , Raghavan Srini
Published: May 2005

An FT-IR attenuated total reflection (ATR) method is described for quantitative in situ analysis of the adsorption and rinsing-removal of surfactants from silicon surfaces. Spectral bands at wavenumbers below 1550 cm−1 are nearly inaccessible when single-crystal silicon ATR internal reflection elements (IREs) are used. A new ATR technique was attempted in order to overcome this limitation. The silicon was sputtered as a thin film onto a thin Al2O3 buffer layer, which had been previously sputtered onto a ZnSe IRE to improve adhesion of the silicon layer. The method allowed observation of species at the silicon/aqueous solution interface below 1550 cm−1, to 1100 cm−1. Absorption bands due to adsorbed octylphenol polyethylene oxide (OPEO) and dodecyl trimethyl ammonium bromide (DTAB) surfactants were observed in the 1550–1100 cm−1 spectral region, which were assigned to benzene-ring modes and the aliphatic stretching vibrations for OPEO and to the aliphatic stretching vibrations for DTAB. A mathematical method to calculate adsorption density for stratified ATR IRE systems having more than three phases (i.e., ZnSe/Al2O3/Si/aqueous solution) was developed and applied to the determination of the adsorption density of DTAB and OPEO surfactants on silicon, in situ. The method was confirmed through spectra obtained with a single-crystal Si IRE and the previous three-phase calculation method. The agreement indicates that the two surfaces have very similar physisorption chemistry. In addition, this method allows direct, in situ observations of the oxidation-induced growth of a Si-O-Si band near 1150 cm−1 and its removal by dilute HF solutions.
Influence of an Electric Field on the Emission and Absorption of Atoms and Ions in a Flame
Authors: Madden Sean P. , Hueber Dennis M. , Smith Benjamin W. , Winefordner James D. , Turk Gregory C.
Published: May 2005

Experiments were carried out to explore the effect of an electric field upon atomic species introduced into a flame. The study involves components from a conventional flame atomic absorption apparatus with 10 × 10-cm parallel plate electrodes as the cathode and the 5-cm slot burner head as the anode. A marked decrease in the emission and absorption of many atomic species was observed, and quantification of the effect was carried out. The effect has been interpreted as a disturbance of the equilibrium, Me ≈ Me+ + e−. Relative decreases in absorption and emission were found to be functions of applied voltage and analyte concentration at low voltages, and constant for high voltages (≍ −2000 V). Temporal behavior of the effect has been investigated by observation of the speed of restoration of the emission signal from Na (589.16 nm), Sr (460.86 nm), and Sr+ (407.89 nm) after rapid elimination of the electric field. The effects were also studied as a function of viewing position in the flame for optimization of the position and comparison of the temporal behavior with the speed of the flame gases.
Enhancing the Sensitivity of Chemical Sensors for Chlorinated Hydrocarbons in Water by the Use of Tapered Silver Halide Fibers and Tunable Diode Lasers
Authors: Göbel Roman , Krska Rudolf , Kellner Robert , Kastner Joachim , Lambrecht Armin , Tacke Maurus , Katzir Abraham
Published: May 2005

Tapered silver halide fibers were used for the first time for high-sensitivity fiber evanescent wave spectroscopic (FEWS) measurements of chlorinated hydrocarbons (CHCs) in water at trace level. The sensor arrangement consisted of a tunable diode laser (TDL) source, a polymer-coated and tapered silver halide fiber, and a direct fiber/mercury cadmium telluride (MCT) detector coupling. A minimum detection limit of 50 μg L−1 was achieved by using a polyisobutylene-coated fiber with a 1:4 tapering ratio. The sensor response is in the minute range and shows reversible analyte enrichment.
Vibrational Spectroscopy of Certain Polymaleic- and Polyacrylic-Based Mesomorphic Polymers
Authors: Tsiourvas Dimitris , Paleos Constantinos M. , Anastassopoulou Jane , Theophanides Theophile
Published: May 2005

The FT-IR/ATR technique has been employed in the investigation of the forces leading to the organization of a number of polymeric materials exhibiting thermotropic liquid crystalline character. Two types of compounds have been studied, i.e., one bearing the carboxylic polar group near the main chain and the other at the end of the side chain. Intermolecular and intramolecular hydrogen bonding between the carboxylic groups was found to lead to the formation of “facing” and “sideways” structures. Enhanced stability of these supramolecular structures was obtained by the presence of intramolecular hydrogen bonds between the amide groups, resulting in the formation of smectic phases. Furthermore, it has been found that the strengthening of hydrogen bonding between carboxylic groups is associated with a weakening of hydrogen bonds between the amide groups.
Application of Monte Carlo Integration to Three-Dimensional Fluorescence Spectrometry
Authors: Yan Yuan , Xu Jin-Gou , Lin Zhu-Guang , Zhao Yi-Bin , Chen Guo-Zhen
Published: May 2005

In this paper, the sensitivity of three-dimensional fluorescence spectrometry (TDFS) is studied by using the total fluorescence intensity, calculated by Monte Carlo integration, instead of conventional single-point intensity. It has been proven that the sensitivity of the total fluorescence intensity method is nearly one hundred times better than that of the single-point intensity method for the determinations of fluorescein and tryptophan. The mechanism of the method has also been studied.
Comparative Surface Adsorption Behavior of High- and Low-Density Lipoproteins as Analyzed by FT-IR/ATR Spectroscopy
Authors: Hu Yuhong , Singh Bal Ram
Published: May 2005

The adsorption behavior of high-density lipoprotein (HDL) and low-density lipoprotein (LDL) onto a zinc selenide crystal surface and cholesterol-modified ZnSe crystal surface has been studied in terms of adsorption kinetics and isotherms with the use of the FT-IR/ATR technique. Adsorption kinetic plots indicated that the adsorption equilibrium of HDL and LDL is reached at 30–40 min, which is similar to the case for other proteins. From the adsorption isotherms of HDL and LDL, transitions from monolayer adsorption to multilayer adsorption were observed at around 10−5 M for both lipoproteins. We also observed that the binding of HDL and LDL to a cholesterol-modified ZnSe surface is less than that to an unmodified ZnSe surface. For example, monolayer adsorption density of HDL on the ZnSe surface was 0.23 pmoles/cm2, whereas it was 0.13 pmoles/cm2 on the cholesterol-modified ZnSe surface.
Linear Raman Spectroscopy on Droplet Chains: A New Experimental Method for the Analysis of Fast Transport Processes and Reactions on Microparticles
Authors: Vehring R. , Moritz H. , Niekamp D. , Schweiger G. , Heinrich P.
Published: May 2005

A new experimental method for the analysis of mass and energy transport and reactions on microparticles is presented. A chain of microdroplets from a vibrating orifice generator was injected into a quiescent gas phase. Linear Raman spectra from the microparticles and the surrounding gas were taken at different distances from the generator. Concentration changes were measured as a function of droplet lifetime. A period of time of up to 20 ms could be studied with a resolution of 10 μs. An argon-ion laser in a 90° scattering geometry was used for excitation. Spectra were taken through a modified double monochromator with a two-dimensional charge-coupled device (CCD) detector, one axis of which was used for spatial resolution. Profiles of gaseous components near the droplets could be measured with a resolution of 50 μm. The method has been applied to analysis of absorption, dissociation, and isomerization in the SO2–H2O system and to the investigation of the desorption process of CO2 from water droplets. Chemical components in gas and liquid phase could be separated. The detection limit in aqueous media was 1 mmol/L.
Convenient Method of Measuring the Chirp Structure of Femtosecond White-Light Continuum Pulses
Authors: Yamaguchi Shoichi , Hamaguchi Hiro-O
Published: May 2005

We have developed a convenient method of measuring the temporal chirp structure of white-light continuum pulses used in femtosecond time-resolved absorption spectroscopy. This method, based on the nonresonant optical Kerr effect, is superior in many respects to the existing one that uses the sum or difference frequency generation by a nonlinear crystal.
Beryllium(II) as a Probe for Study of the Interactions of Metals and Fulvic Acids by Synchronous Fluorescence Spectroscopy
Authors: Silva Joaquim C. G. Esteves Da , Machado Adélio A. S. C. , Garcia Teresa M. O.
Published: May 2005

The interaction of Be(II) with two samples of fulvic acids (fua), extracted from materials present in a pinewood soil (fua2 from upper and fua3 from lower soil horizons), was followed by synchronous molecular fluorescence spectroscopy at pH = 6 and 11. The variations observed in the spectral data were analyzed by evolving factor analysis (EFA). It was found that Be(II) is a useful probe for detecting different ligand structures in complex mixtures of the fua type. The existence of common ligand structures in the two fua samples at both pH values studied was observed. These are probably of the salicylic acid type. Dihydroxylic structures of the catechol type were also detected. The logarithm of the mean conditional stability constants for coordination of the fua ligand structures of the salicylic acid type and Be(II) were obtained (at a pH of 6 and 11, respectively): fua2, 5.85(2) and 5.24(9); fua3, 6.5(1) and 5.08(4). This strong coordination indicates that fua can have an important function in the immobilization of Be(II) dispersed into the environment.
Raman Imaging of Heterogeneous Polymers: A Comparison of Global versus Point Illumination
Authors: Markwort Lars , Kip Bert , Silva Edouard Da , Roussel Bernard
Published: May 2005

Two alternative methods of Raman imaging, via global (wide-field) illumination and via point illumination in combination with confocal light collection, have been applied to the study of heterogeneous polymer systems. From the results obtained it becomes apparent that the fluorescence inherent to most polymer systems severely limits the use of global illumination. Furthermore, the lack in depth resolution in Raman imaging by global illumination ruled out this method for the study of bulk polymer samples. Also as a consequence of the absence of depth resolution, the global illumination technique appeared more vulnerable to artifacts arising from scattering effects due to the sample geometry and fluorescence. Hence, for a general application of Raman imaging to the study of polymer samples, Raman imaging by point illumination in conjunction with confocal light collection is the method of choice
Photothermal Determination of Absorption Coefficients in Optically Dense Fluids: Application to Oleic Acid and Water at CO Laser Wavelengths
Authors: Bicanic Dane , Chirtoc Mihai , Chirtoc Ileana , Favier Jan Paul , Helander Per
Published: May 2005

Values of optical absorption coefficient β in the infrared spectral region covered by the CO laser emission were measured for homogeneous, nonscattering, and optically very dense (4 × 104 m−1 < β< 4 × 105m−1) fluids (oleic acid and water) with the use of optothermal window (OW) spectroscopy. This new approach, which combines a photothermal technique with piezoelectric detection, offers several practical advantages over conventional techniques (easy loading and cleaning, no dead volume, simple recovery of sample, etc.). A linear correlation between the optothermal signal and β exists when thermal diffusion length μ in a sample is shorter than optical penetration depth 1/β. The apparatus was calibrated with distilled water (β = 3.38 × 104 m−1 at 1781 cm−1 wave-numbers). Experimentally found β values for oleic acid and water are consistent with those measured by the spectrophotometric method. Satisfactory measurements could be performed for (0.1 < βμ < 3); the optothermal signals were large enough and far from saturation.
New Method for Spectral Line Shape Fitting and Critique on the Voigt Line Shape Model
Authors: Saarinen Pekka E. , Kauppinen Jyrki K. , Partanen Jari O.
Published: May 2005

In this work we introduce a new method for testing spectral line shape models and optimizing the parameters in any parametric model. Given some general parametric line shape and a piece of a spectrum, the method finds the optimal values for the parameters and gives a number which tells how well the spectrum under consideration is explained by that model. The number of spectral lines under analysis may be more than one, and their exact locations need not be known. This characteristic follows from the property that the method does not need the information about line positions and amplitudes at all. Thus, in the absence of a singlet line, a set of overlapping lines can also be analyzed. The analysis is carried out in the signal domain by utilizing linear prediction. Application examples of the method to a molecular spectrum measured in gas phase are given. The results suggest that the Voigt line shape, despite its common use, is not a correct model in molecular spectroscopy. Its limitations become evident when one is trying to enhance the resolution by linear prediction, which requires detailed knowledge of the line shape. Instead a stochastic model, which is also tested, turns out to be rather promising.
Frequency/Wavelength Calibration of Multipurpose Multichannel Raman Spectrometers. Part II: Calibration Fit Considerations and Calibration Standards
Authors: Carter David A. , Thompson Wade R. , Taylor Chad E. , Pemberton Janne E.
Published: May 2005

Approaches for frequency/wavelength calibration of multichannel Raman spectrometers are presented. These approaches are directed towards practical use in laboratories in which multipurpose or specialized applications result in the need for frequent spectrometer calibration. These approaches are also useful when the sample type or configuration does not permit calibration by more routine methods. Guidelines are presented for effective use of polynomials commonly found in spectrometer calibration software for conversion of pixel number to either wavenumber or wavelength. Guidelines for the selection and use of Raman calibration standards are also presented. Standards currently used for calibration of Raman spectrometers are reviewed. Improved frequency data for indent' and the Ar+ plasma lines are presented, along with frequency data for two materials (imidazole and α-cyclodextrin) which are recommended for use as solid Raman standards.
Some Characteristics of the Hollow Cathode Discharge Source from Hollow Cathodes of Different Sizes and Shapes
Authors: Williams J. C. , Kung Jan-Yurn , Chen Yixin , Cai Xiangjun , Griffin Steven T.
Published: May 2005

The empirical evaluation of several types of two-piece hollow cathodes for the analysis of microsamples using both dc and pulsed discharge modes of the hollow cathode discharge is reported. The discharge parameters used are similar to those that have given good precision and sensitivity for microsamples in this laboratory. Both optical microscopy and scanning electron microscopy were used to follow sputtering effects on the cathode geometry. The sputtering patterns in the flat-bottom, two-piece cylindrical hollow cathode revealed directly the cathode dark space on the cathode cavity bottom. The temporal emission profiles from the spherical cathode cavity are similar to those observed in cylindrical cathode cavities. The temporal emission profile changes with the diameter of the cylindrical cathode cavity and is characteristic of the analyte.
Fractionation Effects in Laser Ablation Inductively Coupled Plasma Mass Spectrometry
Authors: Cromwell Evan F. , Arrowsmith Peter
Published: May 2005

Aspects of laser ablation sample introduction for inductively coupled plasma mass spectrometry (ICPMS) have been investigated. For some analytes, nonrepresentative subsampling or fractionation is the major cause of poor analytical accuracy. Fractionation is prevalent for ablation at low laser fluence and with multiple laser pulses incident on the same area of the sample surface. The fluence dependence is explained by the relative depths of the melt- and heat-affected zones. Volatile analyte elements that are segregated in the bulk, or become segregated as the ablation zone is heated, are most prone to fractionation. For metal alloys, the extent of fractionation can be qualitatively predicted from the binary-phase diagram of the corresponding analyte matrix. Analysis by Auger electron spectroscopy showed that miscible elements may also be segregated at the near surface, with the extent of segregation growing with multiple laser pulses. Such segregation results in increased fractionation.
Frequency/Wavelength Calibration of Multipurpose Multichannel Raman Spectrometers. Part I: Instrumental Factors Affecting Precision
Authors: Carter DavidA. , Pemberton Jeanne E.
Published: May 2005

The accuracy of spectra obtained from a Raman spectrometer is limited by the precision of the spectrometer and the calibration process. As the use of multichannel detectors and the complexity of the experiments in which these detectors are employed increase, a need has developed to understand and address the experimental variables that affect the precision of multichannel detector Raman spectrometer systems. The variables examined in this study include alignment of the laser, sample, collection optics, and monochromator; monochromator precision; backlash; thermal effects; resolution; and detector alignment. The magnitude of errors caused by these variables is reported, and procedures employed for acquiring spectra and experimental configuration changes which reduce the magnitude of these errors are discussed. When used in conjunction with the calibration procedure described in the second part of this series, the approaches described here result in accuracies better than ±1 cm−1 for routine Raman experiments and better than ±2 cm−1 for more complex experiments.
Detection of Dityrosine in Apoferritin
Authors: Mahmoud Sahar F. , Bialkowski Stephen E.
Published: May 2005

Laserexcited fluorescence spectroscopy was adopted for dityrosine detection in horse spleen apoferritin. Dityrosine was identified in horse spleen apoferritin. Fractionation of acid-hydrolyzed horse spleen apoferritin showed fluorescence attributed to dityrosine, and other compounds, excited by 325-nm laser radiation. The other fluorescent compounds resulted in a broad fluorescence emission spectrum of horse spleen apoferritin. The broad emission band overlapped with the fluorescence emission spectrum of pure dityrosine. Fractionation of horse spleen apoferritin acid hydrolysate prior to laser-excited fluorescence detection was necessary for dityrosine quantitative analysis. The concentration of dityrosine in horse spleen apoferritin was 2.5% (mol/mol), estimated from the method of standard addition.
Fast Scanning Synchronous Luminescence Spectrometer Based on Acousto-Optic Tunable Filters
Authors: Hueber Dennis M. , Stevenson Christopher L. , Vo-Dinh Tuan
Published: May 2005

A new luminescence spectrometer based on quartz-collinear acousto-optic tunable filters (AOTFs) and capable of synchronous scanning is described. An acousto-optic tunable filter is an electronically tunable optical bandpass filter. Unlike a tunable grating monochromator, an AOTF has no moving mechanical parts, and an AOTF can be tuned to any wavelength within its operating range in microseconds. These characteristics, combined with the small size of these devices, make AOTFs an important new alternative to conventional monochromators, especially for portable instrumentation. The relevant performance of the AOTFs (efficiency, bandwidth, rejection, etc.) is compared with that of typical small-grating monochromator.
Rapid Optical Purity Determination Using Chiral Spectroscopy, Achiral Spectroscopy, and Multivariate Analysis
Authors: Erskine Steven R. , Quencer Brett M. , Beebe Kenneth R.
Published: May 2005

A chemometric approach for determining enantiomeric purity from chirally sensitive spectral measurements such as circular dichroism (CD) in combination with conventional absorbance spectra has been demonstrated. This approach can be used to monitor process streams to ensure enantiomeric purity of chiral products without the need for chromatographic separation. The approach taken in this paper is a combination of the information available from conventional absorbance spectra, such as UV-Vis or IR, with that obtained by less prominent measurements which are sensitive to optical activity, such as circular dichroism or optical rotatory dispersion (ORD). By coupling these methods, one can obtain information about the concentrations of the desired components in a mixture as well as their enantiomeric purity. This information can be extracted from a number of optically active or optically inactive components simultaneously with the use of readily available multivariate analysis tools such as partial least-squares (PLS) or principal components regression (PCR), a feature unavailable with previously demonstrated single-wavelength measurements. This paper will focus on data from a set of test mixtures to evaluate the accuracy of predictions and to assess the best approach to predict the enantiomeric purities of the test mixtures. Three different mathematical approaches were used, and the results were compared to determine the best method for evaluating this type of data. In addition, the efficiency of this method for predicting enantiomer concentrations in complex mixtures was tested. Partial least-squares was shown to yield the most accurate prediction of the concentrations of even a complex mixture containing similar compounds with nearly indistinguishable spectral features.
Spectral Characterization and Evaluation of Modified Near-Infrared Laser Dyes for DNA Sequencing
Authors: Shealy Dana B. , Lohrmann Rolf , Ruth Jerry R. , Narayanan Narasimhachari , Sutter Scott L. , Casay Guillermo A. , Evans Lawrence , Patonay Gabor
Published: May 2005

Several derivatives of IR-144, a commercially available near-infrared (near-IR) laser dye, have been synthesized with different moieties, which produce bathochromic shifts of the absorbance maximum without affecting their fluorescence emission spectrum. With this capability, the absorbance maximum of the dye can be adjusted to coincide with the maximum output wavelength of various semiconductor laser diodes. This capability allows compatibility with a multidye fluorescence system that has different excitation sources but a common near-IR detector. The utility of IR-144 derivatives with an absorbance maximum close to the output wavelength of commercially available semiconductor laser diodes was illustrated by coupling oligonucleotide primers that contain an amino linker to a dye derivative and sequencing DNA with the use of an instrument designed specifically for near-IR detection. Before sequencing reactions were performed, the near-IR laser dye-DNA conjugates were purified by reversed-phase high-performance liquid chromatography. We report the synthesis and spectral characterization of IR-144 derivatives. In addition, the conjugation reaction between the near-IR laser dye and amino-modified oligonucleotides and subsequent purification is discussed. Data that validate the subfemptomole detection of the labeled DNA strands are presented.
Examinations of Charge Transfer between Ionized He and P, S, and Cl in a Microwave-Induced Plasma
Authors: Brandl Patricia G. , Carnahan Jon W.
Published: May 2005

Charge transfer between monomer helium ions and nonmetals has been postulated to be the source of high nonmetal ion populations in high electron density (> 1014 e−/cm3) discharges. In this study, overpopulations of excited Cl, P, and S ion energy levels in a helium microwave-induced plasma are examined using ion and atom line emission intensity data and charge transfer theory. The resonance emission lines from phosphorous, sulfur, and chlorine were examined. To examine these highly energetic lines, wavelengths in the vacuum-ultraviolet and the ultraviolet-visible (UV-visible) spectral regions were monitored. Energy-level population calculations were performed on similar UV-visible emission data from the literature. Charge transfer ionization cross sections are calculated for these elements. To obtain an indication of the significance of charge transfer, these parameters are compared to the behavior that would be expected if the plasma were in local thermodynamic equilibrium, and kinetically dominant processes such as CT were not considered. These evaluations, with the aid of energy-level diagrams, help to explain the spectroscopic behavior of these nonmetals in the helium discharge.
FT-IR Analysis for Structural Characterization of Albumin Adsorbed on the Reversed-Phase Support RP-C6
Authors: Boulkanz Lahoussine , Balcar Nathalie , Baron Marie-Hélène
Published: May 2005

The aim of this study is to demonstrate the reliability of the use of FT-IR spectroscopy to monitor conformational changes when a protein (HSA) is adsorbed under chromatographic conditions on the silica material RPC6. In the aqueous eluent (D2O), the amount of protein retained on the phase is minimal for 30% CH3CN, whereas no protein is retained for 40%. Structural results are deduced from quantitative analyses of the infrared Amide I' absorptions and from measurements of the peptide NH-ND exchange. Both are performed for HSA in solution and for HSA adsorbed on RP-C6 in suspension in equivalent eluents. For the solutions, 30% CH3CN in the solvent weakly unfolds some structured loops of the protein. Hydration and aggregation are enhanced in 40% CH3CN, which significantly denatures α- and β-domains. When the protein is adsorbed with 0–30% CH3CN in the solvent, about one-tenth of HSA backbone unfolds. In the adsorbed state, the protein is more hydrated and self-associated than in the corresponding solutions. The larger contacts between HSA and RP-C6 are observed when the retention amount is the weakest (30% CH3CN). Results show that retention should have a hydrophobic origin. The irreversibility of the retention is supposed to be dependent on the protein structural and solvation changes observed from the solutions to the adsorbed states. To explain the elution with organic solvent > ∼38%, a competition between acetonitrile and the solid phase in solvating hydrophobic domains of the protein is suggested.
UV-Laser Plasma Study of Elemental Distributions of Paper Coatings
Authors: Häkkänen H. J. , Korppi-Tommola J. E. I.
Published: May 2005

The potential of a laser-generated plasma method in the analysis of coating coverage, coatweight distribution, and 3D distribution of various pigments of paper coating is described. A XeCl-excimer laser (308 nm) was used to generate microscopic plasma from the paper coating, and delayed detection of silicon and calcium atomic emission line intensities was used as a measure of mass vaporized. Macroscopic areas typically 10 × 10 mm2 at a spatial resolution of 250 μm were studied. With a single laser pulse (0.2 mJ of energy), about 2 ng of coating from a volume of 30 μm in diameter and 2 μm in depth was vaporized. The method seems to be useful for characterization of multilayer coatings.
ATR-IR Spectroscopy for the Investigation of Solution Reaction Kinetics: Hydrolysis of Trimethyl Phosphate
Authors: Bayada Anne , Lawrance Geoffrey A. , Maeder Marcel , Molloy Kirsten J.
Published: May 2005

ATR-IR spectroscopy is proposed as a versatile technique for the investigation of reaction kinetics in solution, particularly in aqueous solution. Subtraction of the solvent spectrum and thus quantitative absorption measurements are possible. In contrast to thin-film transmission spectroscopy, thermostatting is feasible. The high information content of IR spectra demands high-resolution spectra measured at many wave-numbers, and, for kinetic investigations, series of spectra are measured. A multivariate nonlinear least-squares fit is proposed that effectively overcomes the difficulties related to large numbers of data and parameters. As a test for the method, the base-catalyzed hydrolysis of trimethyl phosphate in aqueous solution was investigated. The rate constant is 1.6 × 10−1 s−1 at 40°C and pH 13.
Scientifically Operated CCD-Based Spectroscopic System for High-Precision Spectrometric Determinations of Seawater
Authors: Pomeroy Robert S , Baker Mark E. , Denton M. Bonner , Dickson Andrew G.
Published: May 2005

The application of an aberration-corrected imaging spectrograph with the use of fiber-optic inputs and a charge-coupled device detector to produce a sensitive, flexible, and rugged spectroscopic system capable of employment in remote sensing and field applications is presented. This investigation focuses on the optical system design, detector characteristics, and modes of operation that will result in a field instrument capable of both sensitive fluorescence and high-precision absorbance measurements. Evaluation of the optical system used the spectroscopic determination of seawater pH as the test case. Spectral measurements were made with the use of thymol blue as a pH indicator for absorbance and 7-hydroxy-coumarin as the fluorescence pH indicator. This system displayed excellent precision for both absorbance and fluorescence analyses; RSDs for absorbance and fluorescence of ±0.00065 and ±0.0015 in pH, respectively, were experimentally obtained. These findings, along with the advantages of the area array detector to provide simultaneous multiwavelength, multianalyte spectral analysis in a single, rugged optical system, make a strong case for the application of scientifically operated solid-state detector systems to remote sensing and field instrumentation.
DRIFTS and Raman Investigation of N2 and O2 Adsorption on Zeolites at Ambient Temperature
Authors: Smudde George Hc. , Slager Terry L. , Coe Charles G. , MacDougall James E. , Weigel Scott J.
Published: May 2005

Diffuse reflectance infrared fourier transform spectroscopy (DRIFTS) and Raman spectroscopy were used to examine N2 and O2 adsorption on cation-exchanged (K, Na, Sr, Ca, and Li) low silica X (LSX) zeolites. IR and Raman absorption bands were observed for the molecular vibration of adsorbed N2 and O2 at room temperature and atmospheric pressure. The intensity (in Kubelka-Munk units) of the IR band increased with N2 pressure and mirrored the adsorption isotherm for N2. Both O2 and N2 displayed a similar dependence of the molecular vibrational frequency on cation charge density, which suggests that both gases are interacting directly with the cations. The vibrational frequencies for adsorbed N2 and O2 were more sensitive to the cation charge density than to framework Al content. Infrared studies of N2 and O2 on mixed cation forms of LSX show that N2 interaction was localized near individual cations within the sorption cavity of the zeolite. Thus, adsorbed N2 can be used to probe accessibility of specific cations within the zeolite framework. The spectroscopic data are consistent with the theory that the stronger interaction of N2 over O2 is caused by the stronger influence of the electric field with the larger quadrupole of N2.
Flocculation Gradient Technique in Terms of Kubelka—Munk Coefficients: Quantifying Black-Pigmented Dispersions
Authors: Gunde Marta Klanjšek , Orel Zorica Crnjak , Logar Jasmina Kožar , Orel Boris
Published: May 2005

The diffuse reflectance from a painted layer depends upon the layer thickness. The rate of change of diffuse reflectance when thickness increases is the flocculation gradient, which is valuable information about the degree of pigment dispersion in paint. The simple determination method is called the flocculation gradient technique and is suitable to quantify the pigment dispersions in low-absorptive and high-scattering paints. To make the method useful for black-pigmented paints as well, we modified it by applying the Kubelka–Munk theory. This makes it possible to solve the problem of the very narrow linearity region that appears in the diffuse reflectance vs. thickness curve because of high absorption. The modified method allows one to quantify the degree of dispersion in black thickness-sensitive spectrally selective paints, which are used as absorbers in solar collectors.
Effects of Noise on the Interpolation Accuracy for Apodized FFT Spectra of Time-Domain Damped Signals
Authors: Goto Yutaka
Published: May 2005

Interpolation formulas for the apodized magnitude-mode fast Fourier transformed (FFT) spectra determine accurately the frequency, damping constant, and amplitude of time-domain damped signals. However, additive noise causes a large amount of error in interpolation. In this paper, we obtain, theoretically, the frequency-domain signal-to-noise (S/N) ratio due to windowing by the function of sinα( X) and quantization with finite bit-length analog-to-digital (A/D) converters. Then, with the use of the squared ratios between three magnitudes nearest to the peak maximum on the apodized FFT spectrum, we derive the relationship equation between the frequency error and the S/N ratio. The results obtained by computer simulation of experimental conditions (i.e., sampling, quantization, windowing, FFT, and interpolation) for the Hanning window (α = 2) agree well with the theoretical calculations; the frequency errors decrease with increasing bit-length of the A/D converter. These observed errors are unavoidable because A/D converters are indispensable for measurements with Fourier transform spectrometers. Furthermore, as shown theoretically, the observed accuracy of interpolation is inversely proportional to the S/N ratio, provided that the S/N ratio is below the value due to quantization and windowing.
Being En Route
Authors: COUTIN SUSAN BIBLER
Published: May 2005

Through an ethnography of unauthorized migration from El Salvador to the United States, I explore “clandestinity” as a hidden, yet known, dimension of social reality. Unauthorized migrants who are en route to the United States have to make themselves absent from the spaces they occupy. When they become clandestine, such migrants embody illegality; in some cases, they literally “go underground” should they die and be buried en route. Because their presence is prohibited, unauthorized migrants do not fully arrive even when they reach their destinations. There are parallels between the ways that migrants are present in yet absent from nations, and the ways that ethnographers are present in yet absent from the field. This ethnography of migrants en route therefore suggests how anthropological knowledge practices also produce realities that are hidden, yet known.
The Place of “Others” in Hunter‐Gatherer Intensification
Authors: HOLLY DONALD H.
Published: May 2005

Archaeologists are interested in understanding the conditions under which hunter‐gatherer intensification occurs. Typically, most models assign primacy to population pressure or social relations and address intensification as it occurs among foragers inhabiting arid or temperate environments. In this article, I explore episodes of resource intensification and “deintensification” on the subarctic island of Newfoundland. Correlating periods of resource intensification and “deintensification” with changes in the social landscape, I argue that the presence or absence of “Others” played a significant role in informing hunter‐gatherer subsistence strategies and settlement patterns.
“Wild Capitalism” and “Ecocolonialism”: A Tale of Two Rivers
Authors: HARPER KRISTA
Published: May 2005

The development and pollution of two rivers, the Danube and Tisza, have been the site and subject of environmental protests and projects in Hungary since the late 1980s. Protests against the damming of the Danube rallied opposition to the state socialist government, drawing on discourses of national sovereignty and international environmentalism. The Tisza suffered a major environmental disaster in 2000, when a globally financed gold mine in Romania spilled thousands of tons of cyanide and other heavy metals into the river, sending a plume of pollution downriver into neighboring countries. In this article, I examine the symbolic ecologies that emerged in the two moments of environmental protest, as well as Hungarian activists' reflections on the changing political ecology of the region in their discourses of “ecocolonialism” (ökógyarmatosítás) and “wild capitalism” (vadkapitaliszmus).
No Story Is Ever Just a Story
Authors: YATES‐DOERR EMILY
Published: May 2005

The 41 films at the 2004 Margaret Mead Film and Video Festival showcased a multiplicity of styles and approaches, thus widening the perspective of “what counts” as ethnographic film. The two main events—A Tribute to Jean Rouch and Native Voices—epitomized the festival's commitment to diversity and creative talent. Despite the festival's awkward location in the American Museum of Natural History, the films tackled challenging political subjects and directly addressed questions of representation. Postscreening musical performances, informational panels, and audience–director discussion sessions shaped the festival itself as an ethnographic experience, as well as being a venue for the year's best documentary films. Festival highlights were Raven Tales: How Raven Stole the Sun (2004), Mr. Patterns (2004), and Beauty Academy of Kabul (2004).
Building Bridges and Traveling through Time: Ethics, Practice, and Priorities in the Second Moscow International Visual Anthropology Film Festival
Authors: SHECTMAN STANISLAV
Published: May 2005

International film festivals are entangled spaces in which filmmakers and audiences negotiate aesthetic, ethical, political, and practical traditions and communities. This review of the Second Moscow International Visual Anthropology Film Festival explores some of the differences in ethics, practice, and priorities of anthropological filmmaking between Russia and the West. By providing a brief history of Soviet anthropology and a discussion of the festival's main themes, this review explores some of the historic and contemporary influences shaping the development of (one particular strain of) visual anthropology in post‐Soviet Russia.
The Curatorial Voice: U.S. Institutions Exhibit the Ancient Andes
Authors: WISE KAREN
Published: May 2005

Two new exhibits on ancient Andean civilizations are open in the United States. Machu Picchu: Unveiling the Mystery of the Incas is a large traveling exhibition and Tiwanaku: Ancestors of the Inca is a smaller temporary exhibition that is not traveling. Both introduce North American audiences to objects and information that have never been exhibited in the United States and each includes some extraordinary artifacts. The two exhibits differ in many ways: Machu Picchu emphasizes information, archaeological science, and cultural history, whereas Tiwanaku focuses on art style and objects. The curatorial voice and point of view are strong in each exhibit, as is the institutional perspective of its originiating museum. In this respect these exhibits differ significantly from contemporary ones on ancient North America, which generally include the voices and points of view of descendant communities and others.
On a Contradiction in the Discourse on Language Arrangements in EU Institutions
Authors: Marzocchi Carlo
Published: May 2005

On the basis of recent literature on EU language work and of direct observation, this discussion note draws attention to the conflicting translational norms, and ultimately the contradictory discourses on translatorial ethics that inform EU language work. As a paradoxical case in point, a passage of authoritative discourse on the values presiding over EU language services is contrasted with anecdotal evidence of the language use prevaling in the institutions. Possible directions in the search for a less contradictory ethical discourse and translation practice in EU language work are mentioned.