bluuebunny/crossref_metadata_2025 huggingface dataset:
Investigation of Chromatographic Surface Viscosity Using Total Internal Reflection Fluorescence
Authors: Rangnekar Vinay M. , Foley John T. , Oldham Philip B.
Published: June 2005

Total internal reflection fluorescence (TIRF) spectroscopy was employed to determine the viscosity of planar chromatographic surfaces. Various n-alkyldimethylchlorosilanes were used to modify the surface of a UV-quartz plate, so as to obtain a covalently attached monomeric C1, C3, C8, or C18 surface. TIRF anisotropy data of 1, 6-diphenylhexatriene (DPH) were collected on the unmodified and modified surfaces in the presence of overlaying solvents covering a range of viscosities. The results indicate that DPH adsorbs onto C1 and C3, but clearly exhibits partitioning with the C18 phase. The C8 surface data indicate intermediate behavior between adsorption and partitioning. On the basis of these preliminary data, the estimated microviscosity of a planar C18 surface is approximately 18 cP.
Neural Network System for the Identification of Infrared Spectra
Authors: Tanabe Kazutoshi , Tamura Tadao , Uesaka Hiroyuki
Published: June 2005

A neural network system has been developed on a personal computer to identify 1129 infrared spectra. The system is composed of two steps of networks. The first step classifies 1129 spectra into 40 categories, and each unit of the output layer is connected to one of the 40 networks in the second step, which identify each spectrum. Each network is composed of three layers. The input, intermediate, and output layers are composed of 250, 40, and 40 units, respectively. Intensity data at 250 wavenumber points between 1800 and 550 cm−1 of the infrared spectra are entered into the input layer of each network. The training of the networks was carried out with the spectral data of 1129 compounds stored in the SDBS system, and thus the networks were successfully constructed. On the basis of the results, the system has been developed by preparing pre- and post-processing programs. The system can identify each unknown spectrum within 0.1 s, and is quite efficient for identifying infrared spectra on a personal computer.
Near-Infrared Mixture Identification by an Automated Library Searching Method: A Multivariate Approach
Authors: Lo Su-Chin , Brown Chris W.
Published: June 2005

A mathematical technique for the identification of components in the near-infrared spectra of liquid mixtures without any prior chemical information is demonstrated. Originally, the technique was developed for searching mid-infrared spectral libraries. It utilizes principal component analysis to generate an orthonormal reference library and to compute the projections or scores of a mixture spectrum onto the principal space spanned by the orthonormal set. Both library and mixture spectra are analyzed and processed in Fourier domain to enhance the searching performance. A calibration matrix is calculated from library scores and is used to predict the mixture composition. Five liquid mixtures were correctly identified with the use of the calibration algorithm, whereas only one mixture was correctly characterized with a straight dot-product metric. The predictions were verified with the use of an adaptive filter to remove each of the resulting components from the library and the mixture spectra. In addition, a similarity index between the original mixture spectrum and a regenerated mixture spectrum is used as a final confirmation of the predictions. The effects of random noise on the searching method were also examined, and further enhancements of searching performance are suggested for identifying poor-quality mixture spectra.
Dynamic Background Correction by Wavelength Modulation in ICP Atomic Emission Spectrometry (AES) and its Application to Flow-Injection-ICP-AES
Authors: Lépine L. , Provencher M. , Thammavong K. , Tran K. C. , Hubert J.
Published: June 2005

This paper describes a fast background correction system based on wavelength modulation that can be adapted to any dispersive ICP spectrometer. It consists of a quartz refractor plate which oscillates just behind the entrance slit to perform rapid wavelength scanning across the emission line. The system inertia is small and allows a fast scan rate, which permits real-time background measurement during fast transient signals. It has been successfully applied to flow-injection-ICP-atomic emission analysis (FIA-ICP-AES). A simple and inexpensive interface is presented to perform wavelength modulation control and data acquisition by an IBM-XT microcomputer. Different mathematical approaches are compared to handle the spectral line intensity, as well as the FIA-AES peaks. The result is a simplified and fast data treatment which can be easily handled by any small microcomputer.
Chemiluminescent Studies Involving Collisions of CHO+ Ions and CH4 Molecules
Authors: Michael A. , Misra P. , Kushawaha V.
Published: June 2005

Emission bands of the CHO, CH, and OH radicals, together with atomic hydrogen transitions, have been observed due to collisions of CHO+ ions and CH4 molecules. Cross sections of the most intense band of the CH radical have been determined at different laboratory kinetic energies of the CHO+ ions in the range 100 to 900 eV.
Multi-Variate Analysis of Trace Elements from XRF Studies for Classification According to Origin
Authors: Yap C. T.
Published: June 2005

The concentrations of twelve trace elements (Mn, Fe, Co, Ni, Cu, Zn, As, Rb, Sr, Y, Zr, and Nb) in 143 pieces of Chinese porcelain made in Jingdezhen, China and elsewhere were obtained with the use of the energy-dispersive x-ray fluorescence technique. An elegant method of multi-variate analysis, known as principal component analysis, was successfully employed in fingerprinting the geographical origin of the porcelain samples.
Depth Profile of Pyrene Dopant in Polymer Films by Variable-Angle Total Internal Reflection Fluorescence Spectroscopy
Authors: Yanagimachi Masatoshi , Toriumi Minoru , Masuhara Hiroshi
Published: June 2005

The incident and observation angular dependences of the fluorescence from pyrene-doped polymer films are measured by variable-angle total internal reflection fluorescence spectroscopy. These angular profiles depend on refractive index, film thickness, observation wavelength, pyrene concentration, absorption coefficient of the polymer film, and so on. The profiles are in good agreement with the results calculated by fitting the parameters and by considering interference effects and concentration profiles. Step profiles of the pyrene concentration explain the results for the segmented poly(urethaneurea) film, while, in poly(methyl methacrylate) and polystyrene films, pyrene is distributed homogeneously.
Perturbation Theoretical Approach to the Generalized Kubelka-Munk Problem in Nonhomogeneous Optical Media
Authors: Mandelis Andreas , Grossman J. P.
Published: June 2005

The generalized Kubelka-Munk problem is considered in nonhomogeneous optical media with arbitrary depth-dependent absorption and scattering coefficients. Regular perturbation theory is applied to the resulting Riccati equation, and explicit expressions are derived for the diffuse reflectance and transmittance of a finite thickness layer. The first-order perturbation solution to the problem with exponentially distributed absorption and scattering coefficients is presented, and the implications for the quantitative study of nonhomogeneous optical media, such as powdered layers, are discussed.
Simultaneous Determination of Hemoglobin and Myoglobin Oxygen Binding Curves by Spectral Curve Fitting
Authors: Barlow Clyde H. , Kelly Katherine A. , Kelly Jeffrey J.
Published: June 2005

A completely optical method is described for the simultaneous determination of hemoglobin and myoglobin oxygen saturation. Solution oxygen concentrations were computed from measurements of phosphorescence decay of a soluble palladium porphyrin using the Stern-Volmer quenching relationship. Visible absorption spectra were recorded of hemoglobin/myoglobin mixtures progressively deoxygenated by bacterial aerobic metabolism. Separate hemoglobin and myoglobin oxygenation curves were resolved from the spectra of solutions containing both proteins by curve fitting, with the use of singular value decomposition of the spectra vs. oxygen concentration matrix. The method yielded a P50 of 1.2 Torr for horse heart myoglobin at 24 ± 1°C, while the P50 for sheep hemoglobin was 23 Torr at the same temperature. These values, obtained from mixtures, compare favorably with literature values determined for hemoglobin and myoglobin separately.
UV/Vis Spectral Studies on Solution and Single-Crystal Samples Employing a Newly Designed Optical Beam Condenser
Authors: Mullica Donald F. , Wilson Greg A.
Published: June 2005

The development of a new optical beam condenser having been achieved, accurate absorption data on small single crystals are now possible.
Temperature Sensitivity of Near-Infrared Scattering Transmittance Spectra of Water-Adsorbed Starch and Cellulose
Authors: Delwiche Stephen R. , Norris Karl H. , Pitt Ronald E.
Published: June 2005

Near-infrared spectroscopy was used to examine unmodified wheat starch and microcrystalline cellulose (MCC) at temperatures of −80 to 60°C and water activities of 0.22−0.94 aw. A commercially available liquid transmittance cell was modified to permit collection of scattering transmittance spectra of powdered samples. Changes to the shape, peak location, and intensity of the 1400–1500 and 1900–2000 nm water absorption bands were measured as temperature varied. Results indicated that frozen water was not detected at any of the temperatures or aw examined. All water was strongly associated with the carbohydrate matrix so that bulk water was absent. Sharpening of spectral features was not evident at low temperature. However, temperature changes resulted in slight changes to the water absorption bands in the 1400–1500 nm and 1900–2000 nm regions. From −80 to 60°C, the 1900–2000 nm band shifted approximately 10 nm and 15 nm toward shorter wavelengths in starch and MCC, respectively. The direction of shift is consistent with the hypothesis that an increase in temperature results in a decreased proportion of hydrogen bonded water-to-water molecules.
IR and NMR Correlations for Alkyl Isocyanates
Authors: Nyquist R. A. , Jewett G. L.
Published: June 2005

Correlations are presented for υasym.NCO vs. δ(13C) for NCO, δ13C for NCO vs. the number of protons on the alkyl α-carbon atom, and υasym.NCO vs. the number of protons on the alkyl α-carbon atom for alkyl isocyanates. Correlations such as these are useful in the elucidation of unknown molecular structures containing the isocyanate group.
Calibration Transfer and Measurement Stability of Near-Infrared Spectrometers
Authors: Wang Yongdong , Kowalski Bruce R.
Published: June 2005

Near-infrared (NIR) spectroscopy has been widely accepted as a quantitative technique in which multivariate calibration plays an important role. The application of NIR to process analysis, however, has been largely limited by a problem identified as calibration transfer, the attempt to transfer a well-established calibration model from one instrument (e.g., located in the central laboratory) to another instrument of the same type (e.g., located on an industrial process). A calibration transfer method called piecewise direct standardization (PDS) is applied to a set of gasoline samples measured on two different NIR spectrometers. On the basis of the measurement of a small set of transfer samples on both instruments, a structured transformation matrix can be determined and applied to transform spectra between two instruments, enabling the transfer of calibration models. The effect of spectrum preprocessing on standardization is studied with the use of a set of gasoline samples. In a separate study, the day-to-day instrument variation as observed from the change in the polystyrene spectrum is related to the prediction of moisture, oil, protein, and starch content in corn samples, and then the possibility of using such generic standards to replace real samples in a transfer set is explored. In all cases, a standard error for prediction comparable to full set cross-validation is obtained through standardization.
Abscissa Error Detection and Correction in Raman Spectroscopy
Authors: Shen Chengbo , Vickers Thomas J. , Mann Charles K.
Published: June 2005

Attempts to use the linear behavior of Raman spectroscopic measurements in operations such as spectral subtraction may be vitiated by abscissa errors which are smaller than one sampling interval. This paper describes methods, based upon least-squares fitting and Fourier-domain phase shifting, which can be used to locate the positions of peak maxima within 0.05 cm−1. A procedure is described to allow use of these determinations to shift the position of data sets along the X-axis by amounts less than one sampling interval. The effectiveness of this detection and correction procedure is demonstrated by measuring adjusted peak positions. Factor analysis is also used as a probe to examine the operation.
Use of a Holographic Rejection Filter to Improve the Sensitivity of a Commercial Raman Microprobe
Authors: Everall Neil
Published: June 2005

The use of a holographic rejection filter has been demonstrated to improve the sensitivity of a commercial Raman microprobe by a factor of ∼3.5, allowing shorter data accumulation times or a reduction of the laser intensity at the sample. The filter has been tested with two very different solid samples; the first (TiO2 powder) gives a strong diffusely scattered laser beam along with the Raman scatter. The second (silicon) gives a strong specular reflection of the laser beam, again severely testing the laser rejection capabilities of the filter. Bands down to 200 cm−1 shift were transmitted by the filter without attenuation but with satisfactory rejection of the laser line. This approach provides a simple way of enhancing the performance of a commercial microprobe at low cost.
Surface Analysis with FT-IR Emission Spectroscopy
Authors: Sullivan David H. , Conner W. Curtis , Harold Michael P.
Published: June 2005

The technique of infrared emission spectroscopy (IRES) is reviewed and further examined in this study as a surface analysis tool. A system has been designed which allows simultaneous kinetic and in situ infrared emission analysis of catalyst surfaces. IRES spectra of several gas mixture/solid systems are obtained in order to examine sample preparation and spectra processing issues; these systems include Pt/Al2O3 exposed to CO and CO-NO mixtures, an oxidized copper plate, and a zeolite exposed to inert atmospheres. For the temperature range of importance to catalysis (300–600 K), IRES is limited to frequencies less than 2500 cm−1. However, IRES is especially well suited for studying solid-state vibrational modes (<1000 cm−1). Moreover, IRES allows catalyst samples to be studied without dilution or extensive sample preparation. The thin samples required for IRES make it possible to study both surface adsorbate and the solid-state lattice vibrations simultaneously. This information can provide useful insight into the interpretation of kinetic data of reactions on metal oxide catalysts. However, samples which are too thick or are supported on a high-emissivity surface will not yield satisfactory spectra. Two correction techniques are examined which reduce background and sample-reflectance effects in the emission spectra. Some of the IRES data are compared to the corresponding spectra obtained by transmission and diffuse-reflectance spectroscopy. IRES is shown to be competitive with these more popular techniques for IR surface analysis.
Spatial Averaging for Solid Samples by Hadamard Transform Raman Spectroscopy
Authors: Zhu Jianxiong , Mann Charles K. , Vickers Thomas J.
Published: June 2005

A method is described to avoid the effects of sample heterogeneity in Raman measurements on solid samples. A Hadamard multiplex multichannel system with a bifurcated fiber-optic bundle for excitation and collection is used. The Hadamard mask employs a 7-element code with a unit slit width of 400 μm. Results are reported for samples prepared by mixing cytosine and 5-methylcytosine powders.
Asynchronous Time-Resolved Fourier Transform Infrared Spectroscopy
Authors: Masutani Koji , Sugisawa Hisashi , Yokota Akira , Furukawa Yukio , Tasumi Mitsuo
Published: June 2005

A novel asynchronous time-resolved FT-IR spectrophotometer based on a conventional continuous-scan interferometer has been developed. In contrast to the existing methods, this method does not require the synchronization between the signal for time resolving and that for the sampling of the A/D converter. The signal-processing assembly for time-resolved measurements consists of a pulse generator, a pulse delay circuit, a gate circuit, and a low-pass filter. This assembly can be attached to any conventional FT-IR spectrophotometer. By this method, time-resolved spectra without any spectral distortion or artifacts can be obtained for repetitive fast phenomena. As an application of this method, time-resolved FT-IR measurements have been carried out for the reorientation process in a ferroelectric liquid crystal induced by the reversal of external electric field, and a time resolution of 0.5 μs or less has been achieved. The present system is best suited for observing repetitive transient phenomena with lifetimes in the range from approximately 1 μs to 1 ms.
Spectral and Physical Properties of Some Desert Soils: Implications for Remote Spectroscopic Terrain Analysis in Arid Regions
Authors: Eastes John W.
Published: June 2005

Spectral structure between 2.5 and 13.5 μm of a variety of soils collected from the U.S. Southwest and Saudi Arabia is shown to provide qualitative information about composition and texture. Calcite and gypsum, soil components playing significant roles in determining surface hardness, exhibit diagnostic features between 3 and 5 μm which may permit their identification via remote sensing. Gypsum also exhibits high surface reflectance at 8.7 μm; however this feature would be unreliable in a natural setting because it falls in the same spectral region in which quartz displays its strong fundamental. Silicate reflectance between 8 and 12 μm decreases with particle size; thus inferences of soil particle size and texture can potentially be made from spectral data in this region. Such information can be of military importance for forecasting regional vehicle trafficability and dust potential, often crucial concerns in the planning and conduction of tactical field operations.
Complexation of Doxorubicin with β and γ-Cyclodextrins
Authors: Husain Noni , Ndou Thilivhali T. , De La Peña Arsenio Muñoz , Warner Isiah M.
Published: June 2005

The binding of β and γ-cyclodextrins with the anti-cancer drug doxorubicin has been examined with the use of fluorescence and absorbance spectroscopy, circular dichroism measurements, and proton NMR spectroscopy. The stoichiometry of the complexes formed and their apparent formation constants have been estimated with the use of various approaches. The stoichiometrics for both the β-cyclodextrin-doxorubicin complex and the γ-cyclodextrin-doxorubicin complex have been determined to be predominantly 1:1. The strength of the interaction of the drug with γ-cyclodextrin is stronger than that with β-cyclodextrin. The effect of varying the pH on the calculated formation constants of the complexes has also been investigated.
In situ Identification of Thin-Layer Chromatography Fractions by FT Raman Spectroscopy
Authors: Everall Neil J. , Chalmers John M. , Newton Ian D.
Published: June 2005

The use of near-IR-FT Raman spectroscopy for the in situ analysis of fractions on TLC plates is described. The detection of additives in use in the plastics industry is used as an example. Reasonable-quality spectra were obtained from sample loadings equivalent to about 3 μg mm−2 in the most favorable case. Background fluorescence was not a problem, either from the adsorbent or the adsorbate, even when fluorescor was present to aid spot visualization. Similarly, staining with iodine to identify spot positions did not degrade the FT Raman spectra. When a mixture of three additives (200 μg of each) was eluted on a silica TLC plate, two of the additives gave good Raman spectra, sufficient for identification. The third component, a weaker scatterer, had spread over such a large area that the concentration was too weak to give a Raman spectrum visible above the background features from the TLC adsorbent. The concentration of the eluted spot is the limiting factor in this approach since the Raman experiment samples only about 1 mm2 of the total sample area. However, component detection is clearly feasible with the use of this technique, and advances in detector technology should substantially reduce the sample loadings required to effect identification, although it must be realized that background Raman features from the TLC adsorbent will ultimately obscure the spectrum of very dilute loadings of additives. In such cases, sample concentration on the plate will be necessary. A brief comparison with conventional Raman spectra obtained with 514-nm excitation is also made. While good spectra of one additive on silica were obtained, this approach could not be used with plates that contained added fluorescor or that had been stained with iodine for spot visualization, owing to intense background fluorescence. The approach was also prone to fluorescence form the TLC fraction itself and sample degradation.
Comparison of Interferogram Noises in the Ultraviolet and Visible Regions
Authors: Kolar Wesley , Williams Ron
Published: June 2005

The sources of noise in ultraviolet (UV), visible, and near-infrared (NIR) interferograms acquired with silicon and germanium diodes as well as photomultiplier tube (PMT) detectors have been investigated. Similar conditions were used with each detector so that noises could be compared with minimal bias. Interferograms were produced from tungsten and deuterium lamps as well as an inductively coupled plasma (ICP). Data were collected from two instruments; a Mattson Sirius 100 UV/Vis spectrometer, and a Chelsea Instruments FT 500. The signal was the average of 4 to 100 interferograms, while the standard deviation of the data was the noise. In addition to the average and the standard deviation, which are the first two moments of the frequency distribution, the third moment (known as skew) was employed to analyze the symmetry of noise distributions.
Fluorescence-Based Investigations of Alcohol Co-Solvents on the Nature of Cyclodextrin Inclusion Complexation
Authors: Huang Jingfan , Catena Gino C. , Bright Frank V.
Published: June 2005

The effects of aliphatic alcohol co-solvents on the nature of inclusion complexes formed between 2-anilinonaphthalene-6-sulfonic acid (2,6-ANS) and β- or γ-cyclodextrin were studied with the use of steady-state and time-resolved fluorescence spectroscopy. Complementary information about the effects of alcohol on cyclodextrin (CD) inclusion complexation has been obtained. The fluorescence lifetimes are recovered from multifrequency phase and modulation experiments in concert with a global analysis scheme. In all cases, the best fitting model contained two decay times. One of the components of the intensity decay is short lived and discrete and the other is a longer-lived distributed component. Evidence from the emission peak intensity, the center and width of the lifetime distribution, and the molar fraction of lifetime components indicates that alcohol modifiers have two distinct effects on the cyclodextrin inclusion complex. First, alcohol co-solvents can disrupt the 2,6-ANS-CD complex through competitive binding with the CD cavity, and to a lesser extent they increase the bulk solvent hydrophobicity. Second, alcohols can enhance the stability of certain 2,6-ANS inclusion complexes by formation of higher-order complexes (2,6-ANS-CD-ROH n). These two effects are governed by the cavity size and the structure and concentration of the alcohol co-solvents. These observations are consistent with the roles of the van der Waals interactions, the hydrophobic effect, and the stearic effects as important factors in CD inclusion complexation. Finally, the average rotational correlation time, recovered from steady-state anisotropy experiments, indicates that the rotational dynamics of the 2,6-ANS-CD complex are regulated by the size and concentration of the alcohol co-solvent.
Experimental Evaluation of the Nukiyama-Tanasawa Equation for Pneumatically Generated Aerosols Used in Flame Atomic Spectrometry
Authors: Robles Coral , Mora Juan , Canals Antonio
Published: June 2005

The Nukiyama-Tanasawa equation has been checked for its applicability to predict the Sauter mean diameter of aerosols generated pneumatically under the conditions usually employed in FAAS. The measurements of droplet-size distribution have been carried out by means of a laser Fraunhofer diffraction system. The effects of both gas and liquid flows, and solvent physical properties, on experimental and calculated Sauter mean diameters of the aerosols have been studied. The results show that this equation, under normal conditions used in FAAS, correctly describes the trends of Sauter mean diameter variation of aerosols generated pneumatically with respect to the flows of nebulizing gas and liquid. Increases in liquid flow or decreases in gas flow give rise to increases in Sauter mean diameters of the aerosols. However, the absolute values predicted according to the equation far exceed the experimental Sauter mean diameters obtained, the divergences being larger at higher liquid flow/nebulizing gas flow ratios. The overestimation for water ranged from 1.8- to 8.1-fold, and for organic solvents and methanol+water mixtures from 3.6- to 13.3-fold. Under the conditions studied, experimental Sauter mean diameter values for the organic solvents and methanol+water mixtures studied were well below those found for water, under comparable conditions. This result contradicts the predictions of the Nukiyama-Tanasawa equation mainly at high liquid flow/nebulizing gas flow ratios. The main reason for this divergence is the overweighting assigned to the second term of the equation.
Aerosol Interfacing Effects on Discrete Sample Introduction Coupled with Spectrometric Detection
Authors: Koropchak John A. , Allen Lori , Davis Joe M.
Published: June 2005

Aerosol techniques are commonly employed to interface discrete sampling techniques (flow injection analysis and liquid chromatography) with various detectors. The effects of these interfaces on discrete signals have not been described, nor has a rationale been established for presumed differences in band broadening due to aerosol-phase extra-column volume, compared to liquid-phase extra-column volume. In this report, the effects of laminar flow through several transport geometries on signal recovery and band broadening for both wet and desolvated aerosols are investigated. Data presented for the conditions studied indicate that signal losses with linear systems are primarily affected by gravitational settling. Increases in residence time lead to larger losses. Centrifugal effects, which lead to higher losses with coiled systems at high linear velocities, however, appear to have a stabilizing effect at lower velocities. Desolvation significantly reduces the level of gravitational or centrifugal losses via reduction in particle sizes. Band broadening results primarily from convection within laminar flow systems. This result was established on the basis of comparison of real signals with those generated from a convolution routine which mimics the effects of convective dispersion within laminar flows. The relatively high flow rates of aerosol transport systems result in short residence times and small effects of large transport volumes on dispersion. Sample losses also appear to offset band broadening to some extent by reducing peak tailing. Conditions providing efficient analyte transport and signal recovery, as well as low dispersion, can be established.
Near-Infrared Acousto-Optic Filtered Spectroscopic Microscopy: A Solid-State Approach to Chemical Imaging
Authors: Treado Patrick J. , Levin Ira W. , Lewis E. Neil
Published: June 2005

A new instrumental approach for performing spectroscopic imaging microscopy is described. The instrument integrates an acousto-optic tunable filter (AOTF) and charge-coupled-device (CCD) detector with an infinity-corrected microscope for operation in the visible and near-infrared (NIR) spectral regions. Images at moderate spectral resolution (2 nm) and high spatial resolution (1 μim) can be collected rapidly. Data are presented containing 128 × 128 pixels, although images with significantly larger formats can be collected in approximately the same time. In operation, the CCD is used as a true imaging detector, while wavelength selectivity is provided by using the AOTF and quartz tungsten halogen lamp to create a tunable source. The instrument is entirely solid state, containing no moving parts, and can be readily configured for both absorption and reflectance spectroscopies. We present visible absorption spectral images of human epithelial cells, as well as NIR vibrational absorption images of a hydrated phospholipid suspension, to demonstrate the potential of the technique in the study of biological materials. Extensions and future applications of this work are discussed.
Effect of Different Atmospheres on the Excitation Process of TEA-CO2 Laser-Induced Shock Wave Plasma
Authors: Kurniawan H. , Kobayashi T. , Kagawa K.
Published: June 2005

The plasma characteristics and excitation process of laser-induced plasma with the use of a TEA CO2 laser of 750 mJ pulse energy and 100 ns pulse width are studied in different surrounding gases at reduced pressures. From the time-resolved spatial distribution, it is clear that in helium and argon atmospheres, two different excitation processes take place in forming the plasma. The first excitation process is due to the blast wave, while the second process is due to the metastable state of the noble gases. It is believed that this second process transfers metastable energy to the vaporized atoms of the target for emission, even long after the laser bombardment ends, thus giving total emission intensity that is higher in the noble gases than in air. The displacement of the front of the emission line under different atmospheres is also presented.
Raman Spectra from Laser-Processed Lead Zirconate Titanate (PbZr0.3Ti0.7O3) Prepared by a Sol-Gel Process
Authors: Gernet D. , Kiefer W. , Schmidt H.
Published: June 2005

We report on investigations of laser-induced crystallization of PbZr0.3Ti0.7O3 (PZT) gel-powder. By means of micro-Raman spectroscopy, and of optical and scanning electron micrography (SEM), we show that, upon laser irradiation, amorphous PZT material is transformed into microcrystals of the perovskite structure. It was found that the laser-induced crystallization is much faster than crystallization through calcination in a conventional oven.
Structural Differences between Type I and Type IV Collagen in Biological Tissues Studied in vivo by Attenuated Total Reflection/Fourier Transform Infrared Spectroscopy
Authors: Ozaki Yukihiro , Mizuno Aritake , Kaneuchi Fumiko
Published: June 2005

Attenuated total reflection/Fourier transform infrared (ATR/FT-IR) spectra have been obtained in a nondestructive manner for the anterior surface, interior part, and posterior surface of the sclera, for the epithelium, Bowman's membrane, stroma, and endothelium of the cornea, and for the inner section of the Achilles' tendon of a rabbit. The corresponding spectra have been remeasured for the rabbit anterior and posterior lens capsule for purposes of comparison. The spectra of the three parts of the sclera and of the Bowman's membrane and stroma of the cornea are very close to the spectrum of purified type I collagen, confirming that their major components are type I collagen. The spectrum of the tendon is also very similar to that of purified type I collagen, but it contains a small contribution from hyaluronic acid in the 1100-1000 cm−1 region. The amide I bands of the type I collagen-containing tissues are sharp and symmetrical, and their frequencies (1642 cm−1) are almost identical to that (1640 cm−1) of polyglycine II, which takes a 3, helix formation, indicating that the secondary structure of type I collagen in the tissues examined is for practical purposes a slightly modified 31 helix. A comparison of the spectra of the type I collagen-containing tissues and those of the type IV collagen-containing tissues reveals that there are two major differences between them; one is the spectral features in the 1100-1000 cm1 region, where C-O stretching modes of polysaccharide are observed, and the other is the shape and frequency of the amide I band. Besides the peak at 1637 cm−1, the amide I bands of the type IV collagen-containing tissues have shoulders near 1650 and 1655 cm−1. This observation indicates that type IV collagen in the tissues examined assumes primarily a slightly modified 31 helix formation, but the percentages of α-helix and random coil structures are not negligible.
Development of a Fluorescence Quenching Technique to Detect Permeation of Chemical Agent Simulants through Protective Clothing Materials
Authors: Vo-Dinh T. , Pal T.
Published: June 2005

This study involves the development of a new and simple analytical procedure based on a spectrochemical modification (SM) technique, namely fluorescence quenching (FQ) to monitor chemical agent simulants. The FQ technique is applied to evaluate permeation of these compounds through protective clothing materials.
The Influence of Discharge-Tube Cooling on the Performance of Surface-Wave Plasmas Intended as Element-Specific Detectors for Gas Chromatography
Authors: Sing Robert L. A. , Lauzon Claude , Tran Khanh Chi , Hubert Joseph
Published: June 2005

Direct water cooling of the discharge tube of surfatron-sustained plasmas is implemented. Discharge tubes of 2 mm i.d. × 0.1 mm wall thickness are able to sustain He plasmas at incident power levels up to 500 W for prolonged periods without severe degradation. The emission spectra and noise amplitude spectra of water-cooled plasmas are compared to those for the air-cooled, thick-walled discharge tubes commonly employed. Incident power and tube diameter optimizations are discussed.
Nondestructive Determination of the Degree of Saponification Using Concentration Depth Profiling of Functional Groups by FT-IR/ATR Spectroscopy
Authors: Harada Masaaki , Kitamori Takehiko , Teramae Norio , Hashimoto Kiyokazu , Oda Shohei , Sawada Tsuguo
Published: June 2005

Concentration depth profiling of functional groups using FT-IR/ATR spectroscopy has been applied to the nondestructive determination of the degree of saponification. A two-layered film, which had acetyl groups in its surface layer distributed inhomogeneously in the depth direction, was prepared. The dependence of its FT-IR/ATR spectra on incident angles was measured. The degree of saponification was determined on the basis of the concentration depth profile of the acetyl groups obtained from the angular dependency. The results obtained showed good agreement with micro FT-IR and neutralization titration results. This method is judged able to determine functional groups within the range of a few micrometers from the sample surface.
FT-IR External Reflection Spectroscopy at Brewster's Angle
Authors: Ishino Yuichi , Ishida Hatsuo
Published: June 2005

A nondestructive technique for the measurement of infrared spectra of thick, hard, and dark materials has been studied with the use of external reflection spectroscopy. The distortion of the absorption bands which is due to optical effects can be minimized with the use of parallel polarized light which is incident at Brewster's angle. With this technique, it is impossible to observe over-absorption even if the material has a semi-infinite thickness. Also, this technique can be applied to the study of thin films on polymer substrates.
Quantitative Characterization of Fe/Al2O3 Catalysts. Part II: Reduction, Sulfidation, and CO/Hydrogenation Activity
Authors: Hoffmann Douglas P. , Houalla Marwan , Proctor Andrew , Hercules David M.
Published: June 2005

ESCA, Mössbauer spectroscopy, XRD, and CO chemisorption were used to study the reduction and sulfidation reactions of a series of 1 to 24 wt % Fe/Al2O3 catalysts. The speciation and particle size of the active phase were correlated with CO hydrogenation activity data. Two phases were previously identified in all oxidic catalysts: Fe2O3 and Fe+3 in solid solution with the alumina support. The Fe2O3 phase was found to reduce to Fe0 and sulfide to Fe1- xS. For the reduced and sulfided catalysts, Mössbauer was able to identify two iron species which were detected as a single solid solution species in the oxidic catalysts. The two species were found to differ by their location in the alumina support. One species is incorporated within the alumina matrix [Fe+2(A)] and the other species [Fe+2(B)] is present at the alumina surface. Both ESCA and CO chemisorption indicate that the Fe particle size increases with increasing iron loading. The turnover frequency (TOF) for CO hydrogenation appears to be a function of the extent of reduction and particle size of the metallic iron phase.
Estimating Detection Limits in Ultratrace Analysis. Part II: Detecting and Counting Atoms and Molecules
Authors: Stevenson Christopher L. , Winefordner James D.
Published: June 2005

Although the limit of detection (LOD) is a widely used means of indicating the detection power of an analytical technique, the application of conventional detection limit theory is not straightforward with respect to laser spectroscopic methods which are capable of detecting single atoms or molecules in the laser beam. In this paper, theoretical considerations in the detection and evaluation of these methods are addressed on the basis of a simple model of a typical laser spectroscopic experiment; in addition, the theoretical requirements for the precise counting of atoms, and factors which influence the signal variance in the model, are considered. Simple Monte Carlo computer simulations are used to verify and demonstrate the application of the theory of single atom detection (SAD) to typical experimental situations.
Investigation of Eu(III) Binding Sites on Datura Innoxia Using Eu(III) Luminescence
Authors: Ke Huei-Yang D. , Birnbaum Edward R. , Darnall Dennis W. , Jackson Paul J. , Rayson Gary D.
Published: June 2005

A pulsed tunable dye laser has been used to obtain excitation spectra and fluorescence decay curves of solid Eu(III)- Datura innoxia and from a series of Eu(III)-containing complexes. Carboxyl and sulfate groups have been demonstrated to be the dominant functional groups for forming binding sites on the cell wall of Datura innoxia at high (≥4) and low (≤3) pH conditions, respectively. The excitation spectra associated with the 7 F0 → 5 D0 electronic transition of Eu(III) luminescence have been used to provide a measure of the electronic structure factors contributing to the interaction between Eu(III) ions and the binding sites on the cell wall of D. innoxia. The noticeably broadened and asymmetric excitation spectra obtained at high pH conditions are ascribed to multiple binding sites. The corresponding lifetime decay curves exhibited a bi-exponential decay. A pK of 4.5 was determined for the binding of Eu(III) to the cell wall at pH ≥4. Kinetic and thermodynamic studies were also undertaken.
Nondestructive Structural Analysis of Photosynthetic Pigments in Living Rhodobacter Sphaeroides Mutants by Near-Infrared Fourier Transform Raman Spectroscopy
Authors: Okada K. , Nishizawa E. , Fujimoto Y. , Koyama Y. , Muraishi S. , Ozaki Y.
Published: June 2005

The 1064-nm excited Fourier transform Raman spectra have been measured for two kinds of whole living cells of photosynthetic bacteria, Rhodobacter sphaeroides G1C and R26 mutants, to investigate in situ structures of photosynthetic pigments, bacteriochlorophyll- a (BChl- a) and neurosporene (the only carotenoid included in the G1C mutant). The 1064-nm excited spectra consist of contributions from both neurosporene and BChl- a in the light harvesting (LH) complexes (G1C) or from BChl- a alone in the LH complexes (R26). The pattern of the 1064-nm excited spectrum of BChl- a in the LH complexes, whose Raman bands are pre-resonance enhanced via its Qy band, is dramatically different from that of its 355-nm excited spectrum, whose Raman bands are resonance enhanced via the B bands; for example, a band at 1606 cm−1 due to a Ca=Cm stretching mode of BChl- a, which is the most intense in the 355-nm excited spectrum, is barely observed in the 1064-nm excited spectrum. The frequency of the above band indicates that BChl- a in the LH complexes is five-coordinate. Bands due to C=O stretching modes of the 9-keto and 2-acetyl groups of BChl- a appear clearly near 1665 and 1640 cm−1, respectively, in the 1064-nm excited spectra. The frequencies of these C=O stretching bands suggest that most of the 9-keto and 2-acetyl groups of BChl- a in the complexes are involved in intermolecular interaction with the proteins. Bands assignable to Ca=N and Ca=Cb stretching modes, which are, in general, very weak in the 355-nm excited spectra, appear strongly in the 1064-nm excited spectra, implying that their bond lengths are changed sizably in the electronic transitions corresponding to the Qy bands.
Characterization of a 23-mm Torch for Use in Inductively Coupled Plasma Mass Spectrometry
Authors: Norman L. A. , Muñoz M. , Myers D. P. , Ross B. S. , Hieftje G. M.
Published: June 2005

A 23-mm-i.d. torch is described and evaluated for use in inductively coupled plasma mass spectrometry. The plasma operates optimally at 1.50 kW forward power and 19.2 L/min total argon flow. The effect of the customary operating parameters (nebulizer flow rate, rf power, sampling depth, and ion-lens voltages) on analyte signals is discussed. Detection limits, oxide-ion ratios, and doubly charged ion ratios have been measured and are compared with those produced by an 18-mm-i.d. low-flow MAK torch. When compared to the conventional torch, the 23-mm system exhibits comparable detection limits for low-mass ions but better detection limits for high-mass ions (Pb and U). Oxide-ion ratios are lower in the larger torch, but doubly charged ion ratios are higher. Because optimal sampling depths in the larger torch are higher, entrained air in the tail flame causes instability and results in increased ArO+ and ArN+ background signals.
Proton NMR Analysis of Octane Number for Motor Gasoline: Part III
Authors: Ichikawa M. , Nonaka N. , Amano H. , Takada I. , Ishimori S. , Andoh H. , Kumamoto K.
Published: June 2005

A method to evaluate the octane number of automobile gasoline by proton magnetic resonance (PMR) spectrometry has been studied. Twelve samples of marketed winter gasoline, whose octane numbers and compositions were identified according to the ASTM standards, and high-olefin gasoline were used to supplement the insufficient coverage of a previous report with additional data. Then, a linear regression equation regarding the relationship between the octane number and PMR data was prepared from the PMR spectra of the 21 samples used for the previous report, whose octane numbers were known, and the 12 samples used this time. Further, the appropriateness of the regression equation was assessed. This report concerns the results of a study in which the scope of the previous study, lacking sufficient data, has been supplemented with additional data to improve the accuracy of the visual estimation of the octane number using the pattern recognition method. Also, a linear regression equation was obtained and found useful for octane number estimation.
On the Feasibility of Passive Optical Separation of Scatter and Fluorescence
Authors: Carroll Mary K. , Miller Richard M. , Keller Richard A. , Hieftje Gary M.
Published: June 2005

The use of “flat” focusing devices, such as Fresnel lenses and holographic optical elements, for the passive optical separation of fluorescence and scattered light is evaluated theoretically and experimentally. Although “flat” lenses do not focus incident light isochronically, and should therefore have different spatial focusing characteristics for very short pulses (scattered light) and pseudo-continuous-wave signals (fluorescence), the optical quality of the flat lenses tested is insufficient to achieve such discrimination. Additionally, if the coherence length of the fluorescence is less than the difference in optical pathlength from extreme positions on the flat lens, fluorescence cannot be considered to be a pseudo-cw signal; this limitation constrains the potential applications of such instrumentation.
Ultraviolet Raman Spectroscopy Using an Atomic Vapor Filter and Incoherent Excitation
Authors: Pelletier M. J.
Published: June 2005

A far-UV line-rejection filter for Raman spectroscopy having an optical density greater than 5.5, a rejection bandwidth of only a few wavenumbers, and a transmission greater than 80% throughout the Stokes and anti-Stokes regions of the Raman spectrum is described. Raman spectra were collected with the use of this filter to remove elastically scattered light. Mercury penlamps were used for excitation. Good-quality spectra could be obtained with integration times as short as 1 second per wavenumber. The advantages of using an atomic line source rather than a laser-based source to excite far-UV Raman spectra are discussed.
Interaction of a Laser Beam with Metals. Part II: Space-Resolved Studies of Laser-Ablated Plasma Emission
Authors: Lee Yong-Ill , Sawan Samuel P. , Thiem Terry L. , Teng Ye-Yung , Sneddon Joseph
Published: June 2005

Spatial measurements of the emission spectra of a laser-generated plasma were obtained for copper and lead targets. Results showed that the two metals gave quite different sizes of plasma, the plasma formed with copper extending 2 mm, and that with lead extending 5 mm, above the metal surface. Excitation temperatures of the plasma ranged from 13,200 to 17,200 K for copper and 11,700 to 15,300 K for lead.
The Application of Linear PA/FT-IR to Polymer-Related Problems
Authors: Carter R. O.
Published: June 2005

A simplified method has been developed which allows the computation of linear photoacoustic FT-IR spectra using only one sample and one reference interferogram from a commercial, rapid-scan spectrometer. The application of linear computation to photoacoustic infrared data can produce spectra similar to transmission spectra through the reduction, if not elimination, of the saturation artifacts typical of amplitude computation, the usual mode of producing a PA/FT-IR spectrum or a transmission mode spectrum. Comparison of the resulting linear spectra with amplitude spectra has been used to demonstrate the existence of surface layers on top of substrates. Qualitative identification of the surface layer is easier in this mode than in the case where amplitude spectra are obtainted at the extremes of instrument mirror velocity. Additionally, information concerning a polymer matrix in the presence of up to 25 wt % carbon black is contained in linear photoacoustic spectra. Linear photoacoustic FT-IR spectra of carbon-filled samples are easier to interpret in comparison to spectra obtained by amplitude methods.
Optical Effects in IR Spectroscopy: Thickness-Dependent Positions of Absorbance Lines in Spectra of Thin Films
Authors: Gunde Marta Klanjšek
Published: June 2005

Optical effects give rise to thickness-dependent positions of absorbance lines ( v0) in the normal-incidence transmission spectra of thin films. Two reasons can be distinguished. Simple Fresnel refraction on the boundaries of the film shifts the line toward higher wavenumbers, with the maximum increment at small film thicknesses ( d). The second effect is due to multiple reflectance. The interference fringes cause the oscillations of the absorbance line around the mean value, which is defined by the effect of the boundaries. Both effects are more pronounced for broad lines. Whereas for the strong bands the first effect dominates, for the weaker ones both can be seen. The effective dielectric constant of the medium increases the first effect and diminishes the second one. Theoretically predicted vo ( d) curves compare well with absorption line positions in silicon nitride and silicon oxide films deposited on silicon wafers.