bluuebunny/crossref_metadata_2025 huggingface dataset:
Visual tracking of a moving person for a home robot
Authors: Song Kai-Tai , Chlen Chen-Chu
Published: July 2005

This paper presents a visual tracking system for a home robot to pursue a person. The system works by detecting a human face and tracking a person via controlling a two-degree-of-freedom robot head and the robot body. An image processing system has been developed to extract facial features using a complementary metal-oxide semiconductor (CMOS) web camera. An algorithm is proposed to recognize a human face by using skin colour and elliptical edge information of a human face. A digital signal processing (DSP)-based motor control card is designed and implemented for robot motion control. The visual tracking control system has been integrated on a self-constructed prototype home robot. Experimental results show that the robot tracks a person in real-time.
Smarter maintenance through internet-based condition monitoring with indirect sensing, novelty detection, and XML
Authors: Zorriassatine F , Ashraf B , Notini L , Parkin R M , Jackson M R , Coy J
Published: July 2005

In engineering, combining a number of solutions and technologies can result in more effective systems than using only one approach on its own. In particular, it has been shown that in condition monitoring (CM), smarter maintenance systems may be obtained by integrating various sensors together. This paper extends this idea by integrating various non-homogeneous technologies horizontally. The proposed system is an internet-based condition monitoring (e-CM) prototype that can identify abnormal tension in moving belts. It is shown that by applying a classification technique, known as novelty detection, it is possible to decide the status of belt tension by processing the belt vibration signals from an optical sensor (i.e. an indirect sensing approach). A novel method for industrial network communication using XML to create a single standard format for sensor information is also used to link the sensor to the process controller via the internet using the flexible CAN bus technology; this is used together with low-cost microcontrollers with a built-in ethernet link for data acquisition and transmission. The resulting integrated approach is more efficient because: (a) it can reduce waste by minimizing process interruptions caused by direct belt inspection methods while obtaining high detection accuracy (99.67 per cent) and (b) it can provide on-line remote CM that is cost-effective, simple, standardized, and scalable across a wide area and for a relatively large number of sensors. This improvement is especially important when applied to bottleneck processes and critical components.
Fault diagnosis in internal combustion engines using non-linear multivariate statistics
Authors: Antory D , Kruger U , Irwin G , McCullough G
Published: July 2005

This paper presents a statistical-based fault diagnosis scheme for application to internal combustion engines. The scheme relies on an identified model that describes the relationships between a set of recorded engine variables using principal component analysis (PCA). Since combustion cycles are complex in nature and produce non-linear relationships between the recorded engine variables, the paper proposes the use of non-linear PCA (NLPCA). The paper further justifies the use of NLPCA by comparing the model accuracy of the NLPCA model with that of a linear PCA model. A new non-linear variable reconstruction algorithm and bivariate scatter plots are proposed for fault isolation, following the application of NLPCA. The proposed technique allows the diagnosis of different fault types under steady state operating conditions. More precisely, non-linear variable reconstruction can remove the fault signature from the recorded engine data, which allows the identification and isolation of the root cause of abnormal engine behaviour. The paper shows that this can lead to (a) an enhanced identification of potential root causes of abnormal events and (b) the masking of faulty sensor readings. The effectiveness of the enhanced NLPCA-based monitoring scheme is illustrated by its application to a sensor fault and a process fault. The sensor fault relates to a drift in the fuel flow reading, while the process fault relates to a partial blockage of the intercooler. These faults are introduced to a Volkswagen TDI 1.9 litre diesel engine mounted on an experimental engine test bench facility.
Evaluation of Recycling Cyclone Spray Chambers for ICP-AES
Authors: Vieira Peter A. , Zhizhuang He , Chan Shi-Kit , Montaser Akbar
Published: July 2005

Two cyclone spray chambers of different sizes are evaluated for inductively coupled plasma/atomic emission spectrometry. On the basis of a simplified mathematical model, the cut-off diameters of the aerosol droplets are estimated to be 2.2 to 4.3 and 1.8 to 3.5 μm for the large and the small cyclones, respectively. The sample consumption rate can be reduced to about 50 μL/min when the cyclone chamber is used in a recycling mode. In general, the signal-to-background ratios, detection limits, and precisions of the analyte signal intensities obtained with the small cyclone chamber are slightly superior to those achieved with a Scott spray chamber and a recycling gravitational sedimentation chamber. The performance of the recycling cyclone chamber is also evaluated for the determination of copper in the NBS freeze-dried urine.
Phase Transitions and Surface Characterization of Poly (Butylene Terephthalate) Fibers by Photoacoustic and Diffuse Reflectance Fourier Transform Infrared Spectroscopy
Authors: Urban M. W. , Chatzi E. G. , Perry B. C. , Koenig J. L.
Published: July 2005

Diffuse reflectance and photoacoustic (PAS) IR techniques are used for spectral measurements of poly(butylene terephthalate) (PBT) fibers. The spectral observations on the fibers are similar to those observed in films. The stress-induced phase transformation is reversible with annealing of the drawn fibers. The annealing process also increases the amount of crystallinity in the fiber. With the use of recently developed PAS methodology to study orientation of the surface species, the orientation of surface aromatic and carbonyl groups is analyzed. In the alpha phase, the surface aromatic rings are preferentially perpendicular on the surface whereas carbonyl groups are preferentially parallel. A similar orientation is observed in the drawn fibers. Annealing of the drawn fibers changes the orientation of the aromatic rings. Upon annealing, the phenyl rings are preferentially parallel to the surface. The depth of penetration at 3000 cm−1 in PBT fibers is found to be approximately 4 μ.
Guidelines for Measuring Inverse Raman Spectra
Authors: Takayanagi Masao , Hamaguchi Hiro-O , Tasumi Mitsuo
Published: July 2005

Experimental conditions for measuring inverse Raman spectra from liquid samples are examined in both the nonresonant and resonant cases. In the resonant case, broad guidelines are proposed for deciding the sample concentration (absorbance) and the wavelengths of the probe and pump lasers in relation to the absorption band.
The Use of Sample Modulation to Simplify the Experimental Arrangement of Selective Line Modulation in Atomic Emission Spectrometry
Authors: Steele A. W. , Hieftje G. M.
Published: July 2005

Selective spectral line modulation (SLM) is a technique used in atomic spectrometry for recovering analyte signals in the presence of spectral interferences, such as overlapping lines from matrix concomitants and background features from the emission source. Application of SLM usually requires passing the analytical source emission through what is essentially a modulated atom reservoir. In previous work, this system was designed with the use of an array of optical choppers, mirrors, and lenses that directed the radiation through and around a standard atomic-absorption slot burner. In the present study, a sample-modulation device was used in place of this complex array. The device operates by pulsing sample aerosol into a flame, and therefore directly performs the function of a modulated atom reservoir. When used in the SLM experiment, this device considerably simplifies the experimental arrangement. Comparisons are made between the conventional optical arrangement and the sample-modulation device.
Water Chemical Ionization Mass Spectrometry of Aldehydes, Ketones, Esters, and Carboxylic Acids
Authors: Hawthorne Steven B. , Miller David J.
Published: July 2005

Chemical ionization mass spectrometry (CI) of aliphatic and aromatic carbonyl compounds using water as the reagent gas provides intense pseudomolecular ions and class-specific fragmentation patterns that can be used to identify aliphatic aldehydes, ketones, carboxylic acids, and esters. The length of ester acyl and alkyl groups can easily be determined on the basis of loss of alcohols from the protonated parent. Water CI provides for an approximately 200:1 selectivity of carbonyl species over alkanes. No reagent ions are detected above 55 amu, allowing species as small as acetone, propanal, acetic acid, and methyl formate to be identified. When deuterated water was used as the reagent, only the carboxylic acids and β-diketones showed significant H/D exchange. The use of water CI to identify carbonyl compounds in a wastewater from the supercritical water extraction of lignite coal, in lemon oil, and in whiskey volatiles is discussed.
Effect of Modulation Source Properties upon Signal-To-Noise Ratios of Inelastic Electron Tunneling Spectra
Authors: Dethomas F. A. , Dybowski Cecil , Gold Harvey S.
Published: July 2005

Lock-in amplification using ac modulation and second-harmonic detection is routinely employed in such techniques as ac polarography, ac voltammetry, and inelastic electron tunneling spectroscopy (IETS). Properties of the modulation source are shown in the present IET studies to limit the obtainable signal-to-noise ratio of a spectrum. A single inelastic electron tunneling junction is used to demonstrate the effect of various commercial modulation sources on the IET spectrum of benzoic acid on alumina. With all other parameters being held constant, the signal-to-noise ratio of the IET spectrum is found to be inversely correlated with the total harmonic distortion of the modulation source.
A Detailed Study of Noise Sources in Selective Line Modulation Atomic Spectrometry
Authors: Steele A. W. , Hieftje G. M.
Published: July 2005

A detailed theoretical study is presented of the noise sources present in selective spectral line modulation (SLM) atomic emission spectrometry. Shot and flicker noise terms associated with the signal and background radiation, the modulating-reservoir transmission, the modulating-reservoir atom emission, the modulating-atom absorption, and the readout system are considered and compared. The results of the study reveal that shot noise never limits the precision of an SLM experiment. Instead, precision at high signal levels is limited by flicker noise associated with the modulating-atom reservoir transmission, the modulating-atom absorption, and the primary emission signal. In contrast, precision near the detection limit is limited by flicker noise associated with the modulating-atom emission and the background emission from the source and modulating-atom reservoir. The relative magnitudes of these noise sources were found to vary considerably with experimental conditions. Experimental data on four elements (Bi, Mg, Cu, Ag) are presented and compared. General trends of the noise magnitudes with experimental conditions are discussed and findings are extended to other elements that can be determined by the SLM method.
Rapid Determination of Analytical Aerosol Size Characteristics
Authors: Skogerboe R. K. , Freeland S. J. , Kronholm K. G.
Published: July 2005

A method in which a cascade impactor is interfaced directly to an atomic absorption system to allow measurements of the masses of analyte associated with various droplet sizes is described. Data are presented which indicate that this measurement approach conveniently provides results equivalent to those obtained by the indirect protocol used by others [see M. S. Cresser and R. F. Browner, Spectrochim, Acta 35B, 73 (1980)] when a filter is used to collect the analyte transported through the impactor. In addition to saving analysis time while providing reliable results, the method is shown to prevent positive size measurement biases due to failure to collect aerosol not trapped by an impactor.
Accuracy and Linearity in UV Spectrophotometry with a Liquid Absorbance Standard
Authors: Gil Manuel , Escolar Daniel , Iza Nerea , Montero Jose Luis
Published: July 2005

Estimations of the uncertainty of eight significant values (λ = 235, 257, 313, 322, 323, 345, 346, and 350 nm) of apparent molar absorptivities in the UV region have been obtained for acidic potassium dichromate solutions at pH 2.21–2.25, recommended as Standard Reference Materials (SRMs). The uncertainties include all the usual sources of possible systematic error in a commercial microprocessor-controlled spectrophotometer. The comparison of these values with those provided by the National Bureau of Standards (U.S.A.) indicates that a precision of ±0.40% has been obtained throughout the absorptivity range. Likewise, the uncertainty in the linearity of experimental absorbances for the eight wavelengths has been estimated, and a table has been drawn up of the absorptivity values and their uncertainties at 10-nm increments over the wavelength range of 200 to 500 nm.
Application of Band Shape Analysis to Infrared Spectra of Adsorbed Species on Solid Catalysts
Authors: Miyata H. , Fujii K. , Inui S. , Kubokawa Y.
Published: July 2005

Band shape analysis has been applied to the infrared spectra of adsorbed species on solid catalysts. It is found that a small computer system with a CRT graphic display is a powerful tool for data refinement. At first, peak parameters are estimated from the second-derivative curve, which has been smoothed; then follows the correction routine. The system can give quantitative information for a severely overlapped spectrum. It is found that the infrared bands of iron pentacarbonyl adsorbed on TiO2 consist of two groups such as hydride carbonyl and the carbonyl species bonded to the Lewis acidic sites on TiO2.
Raman Spectroscopic Identification of Bilirubin-Type Gallstone
Authors: Zheng Siding , Tu Anthony T.
Published: July 2005

A gallstone from Egypt was examined by laser Raman spectroscopy and identified to be a bilirubin-type stone. The surface of the stone, the subsurface interior, and the center of the stone were irradiated with the 514.5-nm argon-ion laser line. Spectra from the three areas gave similar Raman spectral patterns. Moreover, Raman spectra from the interior of the gallstone were identical to that of bilirubin standard. However, the examination of a Raman spectrum from the outer surface of the stone indicated that it contained cholesterol in addition to bilirubin. Bilirubin has the characteristic line of C=C stretching vibration at 1615 cm−1. Cholesterol has the characteristic line of C(5)=C(6) stretching vibration at 1674 cm−1. Cholesterol also has a strong characteristic line at 1439 cm−1. Therefore, it is quite easy to identify the constituents of gallstone by Raman spectroscopy.
Instrumental Neutron Activation Analysis of River Sediments from Rio Tigre (Venezuela) Employing a Planar Germanium Detector
Authors: Labrecque J. J. , Rosales P. A. , Mejias G.
Published: July 2005

Thirteen elements and eleven rare-earth elements (La, Ce, Nd, Sm, Eu, Gd, Tb, Ho, Tm, Yb, and Lu), as well as thorium and uranium, were determined in river sediment samples from the Tigre River, Venezuela, by instrumental neutron activation analysis employing a low-energy photon detector. The analyses were performed on the <63-μm grain size fraction by the following scheme: one irradiation for only 5 h in IVIC's RV-1 nuclear reactor followed by three counting periods, approximately one, three, and seven weeks after the irradiation. This scheme was employed with the purpose of being able to routinely analyze many samples rather than to optimize thirteen different element determinations.
Raman Study of Intermolecular Interactions in Supercritical Solutions of Naphthalene in CO2
Authors: Zerda T. W. , Song X. , Jonas J.
Published: July 2005

The high-pressure Raman spectra of the v1 and 2 v2 Fermi doublet of CO2 and the C-H stretching, C-H bending and C-C-C breathing modes of naphthalene have been studied at pressures varying up to 2000 bar and temperatures between 60 and 90°C. The naphthalene bands show a blue frequency shift with increasing density, whereas a red shift for the Fermi resonance free stretching mode of CO2 is observed with increasing density. The blue shift is explained in terms of repulsive interactions probed by the naphthalene vibrations, while the red shift is related to the attractive forces dominating in the intermolecular potential as seen by the CO2 stretching mode. The experimental results support the validity of the site-to-site model of intermolecular potential. The intermolecular potential between naphthalene and CO2 is assumed to be anisotropic, and the proposed electrostatic quadrupole-quadrupole model of these interactions effectively explains the anisotropy in the intermolecular potential, the energy of association, and the frequency shifts.
Aerosol Ionic Redistribution: The Calcium-Phosphorus Solute Vaporization Effect Revisited
Authors: Kronholm K. G. , Skogerboe R. K.
Published: July 2005

It has been shown that the addition of excess phosphate to calcium solutions causes redistribution of the calcium into smaller aerosol size ranges and significant reductions in the median calcium aerosol diameters. Addition of lanthanum as a releasing agent causes the median diameter for Ca aerosol to return to the value observed in the absence of phosphate and a concomitant reduction in the median diameter of the phosphate aerosol. Such redistribution effects cause changes in the phosphate-calcium concentration ratios and the stoichiometrics of the calcium-phosphorus entities that can be formed. Thus, the effect of phosphate on calcium absorbance may be an enhancement for smaller aerosol diameters and a suppression for larger diameters.
Structural Information from the Integrated Intensity of the OH-Stretching Band of Saturated Alcohols
Authors: Singelenberg F. A. J. , Lutz E. T. G. , Van Der Maas J. H.
Published: July 2005

The integrated intensity, A, of the free OH-stretching band of a large number of noncyclic and six-membered cyclic saturated monohydroxy compounds has been studied as a possible source of structural information. The intensity of primary alcohols proves to be constant, viz., 16.8 ± 0.5 km/M. No factors have been found that influence this value. The standard A-value for secondary alcohols is 13.8 ± 0.4 km/M. OH-rotamers without trans-H-Oxygen-lone-pair interaction show a lower intensity; factors influencing the rotamer distribution might thus affect the overall A-value. A significant decrease is observed when a γ-methyl group is situated (very) close to and therefore strongly interacts with a lone pair of the oxygen atom. The standard A-value for tertiary alcohols is 11.2 ± 0.6 km/M. Initially all rotamers have the same A-value, but for the secondary ones a strongly interacting γ-methyl group may cause an appreciable intensity lowering. Besides, strong sterical interactions between the three alkyl substituents at the α-C-atom usually give rise to small changes in the intensity. The overall conclusion is that the integrated intensity proves to be a useful source of structural information.
A Cryogenic Cell for Liquid Noble Gases. Vibrational Spectroscopy and Photochemistry of Transition Metal Carbonyls in Liquid Xenon
Authors: Andréa R. R. , Luyten H. , Vuurman M. A. , Stufkens D. J. , Oskam A.
Published: July 2005

The construction of a special cryogenic cell for spectroscopic and photochemical measurements in liquefied noble gases under pressure is described. The inner (sample) cell, withstanding a pressure of at least 700 psi, has no high-vacuum around it. It has two crossed IR and UV-visible optical pathways of 30 mm. The usefulness of these noble gases in vibrational spectroscopy is demonstrated for the following transition metal carbonyls, dissolved in liquid xenon (=LXe, pressure <150 psi, 170 < T < 240 K): [W(CO)6], [Mn2(CO)10l, and [Co2(CO)8]. The great advantage of LXe is its complete transparency over a wide spectral range. The limited solubility of many complexes in LXe in comparison with “normal” solvents is often compensated by the long optical pathway of the cell. Because of its complete inertness, reactive intermediates and products of photochemical reactions can be stabilized in LXe, even at moderate temperatures. The photochemical reaction is described of [W(CO)6] with a l,4-diaza-l,3-butadiene (=R-DAB; RN=CHCH=NR) ligand. During this reaction a photoproduct is identified as a stable complex which is so unstable in normal solvents that it can only be observed with rapid-scan FT-IR spectroscopy.
A Modulated Sample-Introduction System for ICP-Atomic Emission Spectrometry
Authors: Steele A. W. , Hieftje G. M.
Published: July 2005

A modulated sample-introduction device for use in inductively coupled plasma emission spectrometry has been constructed and evaluated. With this device, the flow of aerosol to the excitation source is modulated by applying at a specific frequency a pressure pulse to the nebulizer chamber; the use of frequency-selective detection then permits efficient signal recovery. Unfortunately, background emission from the ICP was also found to be modulated at the sample-introduction frequency; the magnitude of background modulation depends on the depth of sample modulation and the types of spectral features present at the analytical line of interest. The sample-modulation device discriminated best between analyte emission and continuum background radiation, but performed most poorly when OH band emission was the dominant background interference. The construction and operation of the device are described and its performance for several elements is evaluated in terms of detection limits, S/B enhancement, and working-curve linearity.
Optimization of Diffuse Reflectance Infrared Spectroscopy Accessories
Authors: Hirschfeld T.
Published: July 2005

The value of diffuse reflectance as an infrared or near-infrared spectroscopic sampling procedure has been limited by the low efficiency of accessories designed for it. In terms of signal-to-noise ratio, these average 2–6% for integrating spheres and 10–12% for various ellipsoidal mirror arrangements. Much better performances, up to 37% efficiency, can be obtained by optimizing a concentric confocal ellipsoidal mirror arrangement by using a very large central opening in the amular collector mirror, and adapting the throughput of the detector to the geometry of the collected beam.
Photoacoustic Studies on Neutron-Irradiated Rare Earth Oxide Powers
Authors: Rai V. N. , Thakur S. N. , Rai D. K.
Published: July 2005

The effect of neutron irradiation on the photoacoustic spectra of Er2O3 and Nd2O3 in powder form has been studied. The irradiation shows a quenching effect on the photoacoustic signal which regains its intensity after a lapse of some time. It is believed that the irradiation changes the oxidation state of the rare-earth ions from M3+ to M2+. The half-life of the recovery process Er2+ to Er3+ in the case of irradiated Er2O3 is found to be 46 h.
Optical Detection of Laser-Induced Ionization: A Study of the Time Decay of Strontium Ions in the Air-Acetylene Flame
Authors: Turk G. C. , Omenetto N.
Published: July 2005

Strontium atoms in the air-acetylene flame are directly photoionized in two steps provided by one dye laser tuned at the resonance ground-state transition (460.733 nm) and by the excimer pump beam at 308 nm, partially split from the amplifier section of the dye laser. The ions produced are then monitored by a third laser beam, colinear and counterpropagating in the flame, tuned to an ionic fluorescence transition and delayed in time with respect to the ionizing beams. In this way a fast decay, which is not affected by variations in the electron number density in the flame and therefore attributed to ion chemistry, and a slow decay, due to recombination, could clearly be observed. The fast decay is affected by variations in the flame stoichiometry and the slow decay by the number density of electrons in the flame, as shown by the addition of varying concentrations of an easily ionized element like caesium. The advantages of this optical probing of the laser-induced ionization in flames are discussed.
Raman Spectroscopy of Bulk Bismuth Molybdate Catalysts
Authors: Kovats William D. , Hill Charles G.
Published: July 2005

The Raman spectra of bismuth molybdate catalysts were recorded under a variety of conditions. At 200°C under evacuation, a peak at 1575 cm−1 was observed in the spectra of alpha, beta, and gamma bismuth molybdates and Fe2Mo3O12. There was no peak in this location in the spectra of MoO3 and Bi2O3. For alpha bismuth molybdate, this peak could be generated by room-temperature evacuation or by reduction of a fully oxidized catalyst with propylene at 400°C. This latter treatment had the additional effect of causing a dramatic decrease in the intensities of bands in the fundamental region (<1000 cm−1), although no changes in the relative intensities or locations of these bands were observed. The intensity decreases were attributed to the concomitant generation of a large number of free electrons within the catalyst. Reoxidation reversed this effect. The 1575-cm−1 peak could be removed by contact with O2 at 350°C. In addition, a band at 1375 cm−1 was sometimes observed; its intensity relative to the 1575-cm−1 band was temperature-dependent. It was not plausible to assign these bands to fundamental, overtone, or combination bands associated with Mo-O or Bi-O bonds. It appears that these bands are related to the presence of an electron donor level which can inelastically scatter light during an electronic transition.
Diode Array Spectrophotometry of Translucent Materials
Authors: Englebreth William R. , Mann Charles K. , Vickers Thomas J.
Published: July 2005

The light scattered from translucent samples is used to obtain absorption-type spectra and provide quantitation of an absorber within the scattering bodies. Synthetic vesicles with an encapsulated dye, bromothymol blue (BTB), are employed as a novel model system to study the properties of translucent samples. Chlorophyll measurement in intact phytoplankton and algae is demonstrated. A least-squares fitting procedure is used to overcome the effect of chlorophyll fluorescence on the scattering data. A straight line relationship between a defined pseudo-absorbance and concentration is shown for both the BTB and chlorophyll data. A limit of detection of about 0.2 mg/L BTB is obtained for the synthetic vesicles. For chlorophyll the limit of detection is in the range of 1 to 5% of that found in the native plankton and algae samples.
FT-IR Photothermal Beam Deflection Spectroscopy of Solids Submerged in Liquids
Authors: Varlashkin P. G. , Low M. J. D.
Published: July 2005

FT-IR photothermal beam deflection (PBD) spectra were recorded of solids submerged in liquid CCl4 and in C2Cl4. Some PBD effects are described. Submerging the sample leads to PBD signals 40 times larger than those found with the sample in air, but the signal-to-noise ratio of FT-IR/PBD spectra is only increased by a factor of ten. Certain aspects of the technique and its utility are discussed.
Three-Dimensional Atomic Spectra in Flames Using Stepwise Excitation Laser-Enhanced Ionization Spectroscopy
Authors: Turk G. C. , Ruegg F. C. , Travis J. C. , Devoe J. R.
Published: July 2005

Stepwise excitation laser-enhanced ionization spectroscopy utilizes two independently tunable dye lasers to populate high-lying excited states of atoms in flames. Two atomic resonances are required, with the upper level of the first-step transition coinciding with the lower level of the second-step transition. Efficient population of a high-lying atomic level is achieved, from which a high rate of collisional ionization can take place. The double-resonance aspect of such excitation adds an extra dimension of spectroscopic selectivity to the measurement. A computer-controlled dual-wavelength LEI spectrometer, including a Fizeau wave-meter for wavelength verification, is used to record three-dimensional spectra–ionization signal as a function of both first- and second-step wavelengths. Examples illustrate the accuracy advantage accorded by the three-dimensional survey.
Stark Structure Observation in Rydberg States of Li in Flames by Laser-Enhanced Ionization: A New Method for Probing Local Electrical Fields in Flames
Authors: Axner O. , Berglind T.
Published: July 2005

In Laser-Enhanced Ionization spectrometry (LEI) in flames the measured signal consists of the electrons and ionized atoms which follow a laser excitation due to the enhanced thermal ionization rate of an excited state compared with the ground state. The charged particles are collected by applying a voltage across the flame and measuring the corresponding current increase. The authors report the observation of the linear Stark effect in highly excited states of Li in flames when laser-enhanced ionization is utilized. The experiments show good agreement with the theory for the linear Stark effect. The atoms were excited by ultraviolet light from the ground state (2s) to np states ( n = 8–22). Collisional broadening is the dominant broadening mechanism for the lower states while the Stark effect dominates at higher values of n for laboratory electrical field strengths. In the analytical use of LEI for trace element analysis the presence of the Stark effect leads to a reduction of the sensitivity of the method, because it decreases the peak-height of the signal. A new method, which utilizes the Stark effect, is presented for nonintrusive determination of the electrical field distribution in flames.
The Rapid Determination of Gold on Activated Carbon by X-Ray-Fluorescence Spectrometry Using Radioactive Isotopes
Authors: Balaes A. M. E.
Published: July 2005

A method is presented for the rapid (15 to 20 min) analysis of activated carbon from carbon-in-pulp (CIP) plants for its gold content. The method involves the use of microprocessor-controlled energy-dispersive x-ray-fluorescence spectrometer, using excitation by the radioactive isotope 218Pu, and a background-ratio technique to correct for small variations in the matrix. The gold can be determined in dried granular carbon and milled carbon, provided that the calibration standards and samples are in the same physical form. It is shown that, because of the large differences in composition of the matrices of loaded and eluted carbon, two calibration curves need to be established, one for gold concentrations lower than 200 μg/g, the other for gold concentrations higher than 200 μg/g. The calibration curves for milled carbon showed less scattering of the calibration points than those for granular carbon, and the relative standard deviation of the results for milled carbon was 1% as against 2% for granular carbon.
Intracavity Helium-Neon Laser Photothermal Deflection as a Sensitive Technique for Trace Gas Analysis
Authors: Tran Chieu D.
Published: July 2005

A novel, compact, ultrasensitive, and inexpensive He-Ne laser intracavity photothermal deflection spectrometer has been developed. In this apparatus a gas sample is placed inside a cavity of the He-Ne laser, which serves as a probe laser. A CO2 excitation laser coaxially overlaps with the He-Ne laser beam inside the sample cell. The detection limit for ethanol vapor in air at 1 atm excited with 1.5 W of CO2 laser chopped at 13.3 Hz is estimated to be 2.5 ppb.
The Quantitative Analysis of Boron Oxide in Borosilicate Glasses by Infrared Spectroscopy
Authors: Haaland David M.
Published: July 2005

Classical multivariate least-squares methods have been applied to the quantitative analysis of boron oxide in bulk borosilicate glasses using transmission infrared spectroscopy. However, molecular interactions in the glass result in deviations from Beer's law and cause the analytical B-O overtone band at ∼2680 cm1 to shift to higher energy with increased boron concentration. Therefore, in order to account for the molecular interactions and achieve higher quantitative accuracy, one must use a nonlinear model relating absorbance and concentration. It has been found that if a quadratic correction term is added to the Beer's-law equation, the observed 15 to 25 cm−1 shift in frequency of the B-O overtone band can be modeled to within the spectral noise. With the use of a model quadratic in boron oxide concentration, the least-squares analysis of boron in glass was determined with an average relative error of 3.3% for glasses with boron oxide concentrations ranging from 0.88 to 2.58%. This compares favorably with the 3% accuracy claimed for ion chromatography exclusion used for calibration. The methods described in this paper are general, and a variety of nonlinear models can be applied whenever Beer's-law deviations are present.
Infrared Spectroscopic Characterization of Silicon Nitride Films—Optical Dispersion Induced Frequency Shifts
Authors: Knolle W. R. , Allara D. L.
Published: July 2005

Films of Si3N4 on Si substrates were prepared by both sputtering and low pressure chemical vapor deposition. Infrared transmission measurements of the strong 800–900 cm−1 Si-N absorption show large (up to 50 cm−1) shifts as a function of film thickness in the range ∼0.1 to 1.2 μm. The agreement between experimental spectra and simulated spectra calculated from parallel layer optical theory indicates that these shifts can be attributed primarily to optical dispersion distortion effects. However, there is some discrepancy between experiment and theory at the extreme ends of the thickness range for the sputtered films which suggests small intrinsic structural changes of these films may arise as a function of deposition thickness. These results point out the importance of considering optical effects in the interpretation of thin film spectra.
Micro-Diffuse Reflectance and Matrix Isolation Fourier Transform Infrared Techniques for the Identification of Tetrachlorodibenzodioxins
Authors: Gurka Donald F. , Brasch Jimmie W. , Barnes Russell H. , Riggle Charles J. , Bourne Sidney
Published: July 2005

Micro-diffuse reflectance Fourier transform infrared (DRIFT) and matrix isolation (MI) Fourier transform infrared spectra of the 22 tetrachlorodibenzodioxin (TCDD) isomers have been recorded. The DRIFT and MI techniques required about four minutes and one-half minute, respectively, of signal averaging to produce high signal-to-noise (S/N) spectra on low-nanogram-level samples. Spectral subtraction was employed to remove DRIFT solvent impurity interferences. The validity of the DRIFT subtraction technique was demonstrated by comparison of the corrected DRIFT, with the chromatographically pure, MI spectra. The reproducibility of DRIFT frequencies and intensities was tested by comparison of the 1,3,7,8-TCDD spectra from samples independently prepared by two analysts. The MI technique successfully identified 2,3,7,8 in environmental samples. MI spectral subtraction was applied to one sample to remove a coeluting impurity. The DRIFT and MI spectral techniques, used in conjunction with modern chromatographic separation and spectral subtraction, are very promising for the on-line or off-line differentiation of low-level toxic isomeric compounds.
A Monte Carlo Simulation for Graphite Furnace Atomization of Copper
Authors: Black Sador S. , Riddle Mary R. , Holcombe James A.
Published: July 2005

Monte Carlo simulation techniques are used to model the release of Cu from a graphite furnace atomizer during the heating pulse. The simulation allows for control of nonuniform axial temperature distribution of the furnace, surface readsorption of the analyte, and various furnace geometries and initial sample location. Spatial maps of the particles are obtained as a function of time during the simulations, and axial and radial spatial distributions of the analyte particles are presented for Cu. Spatially integrated and spatially resolved absorbance profiles from experimental measurements are also presented for comparison. Explanations of the Monte Carlo approach are given and the equations used to govern release and loss are presented. The approach relies heavily on physical/chemical constants rather than curve fitting approaches. The release of Cu is a first-order process proceeding from submonolayer coverages on the surface with an activation energy of 29 ± 3 kcal. With the use of a kinetic approach for the release and readsorption it was found that the rate of release and rate of readsorption were nearly identical. This suggests that equilibrium is approached at the gas/graphite interface for Cu under these conditions. At the peak approximately 10% of the original sample is within the furnace volume as a vapor. At 900 K/s heating rate, convective expulsion of the analyte is negligible in comparison to diffusive loss. However, in a mini-Massman-type furnace the presence of the sample introduction hole is responsible for 35% of the analyte lost. This is in contrast to the 11% predicted by area considerations alone.
Depth-Profiling Studies of Double-Layer PVF2-on-PET Films by Fourier Transform Infrared Photoacoustic Spectroscopy
Authors: Urban Marek W. , Koenig Jack L.
Published: July 2005

Photoacoustic Fourier transform infrared spectroscopy (PA/FT-IR) is used to study films of poly(vinylidine fluoride) (PVF2) and poly(ethylene terephthalate) (PET). It is shown that PVF2 films over PET change the thermal diffusion length such that the sample PVF2-on-PET becomes optically transparent and thermally thick. By changing the mirror velocity of the Michelson interferometer it is possible to obtain spectra at various sample depths. The intensity of the carbonyl band of the lower PET film changes as a function of the mirror velocity. The log-log plot of these quantities gives a slope of −3/2, which agrees with theoretical predictions for thermally thick and optically transparent samples.
Accounting for Impurities in Spectroscopic Multicomponent Analysis Using Fourier Vectors
Authors: Brown Chris W. , Bump Elizabeth A. , Obremski Robert J.
Published: July 2005

Two methods are presented for dealing with impurities in unknown samples subjected to spectroscopic analysis. In one method, a residual is calculated, and its relative length is used to “flag” that particular sample as a suspect. In the second method, a representation is found for the impurity from the analysis of standard samples without knowing its concentration. This representation is used to deal with the impurity in unknowns. All spectra are Fourier transformed, and terms of the transforms are selected as coordinates of vectors. The vectors for standard mixtures are factor analyzed to determine eigenvectors which are used to represent both the analytes and impurities.
Application of Attenuated Total Reflection Infrared Spectroscopy to the Characterization of Coal
Authors: Mielczarski Jerzy A. , Deńca Andrzej , Strojek Jerzy W.
Published: July 2005

Attenuated total reflection (ATR) spectroscopy in the infrared has been applied to the study of the surface structure of various rank coals. No special time-consuming pretreatment of the sample is required which could effect the results. The sample is simply contacted with a reflection element. The method offers a possibility of a spectral study of the surface of the coal samples with graining up to several dozens of micrometers, and the scattering effect is not observed. In the low-temperature (130°C) coal oxidation process a formation of carbonyl and carboxyl groups (the band at 1700 cm−1) and a change in intensity for the rest of the bands have been observed. Oxidation of low-rank coals causes changes mainly in the aliphatic groups of the coal, while in the case of the highest-rank coal the changes in the aromatic structures are more marked.
The Application of DRIFT Spectroscopy to Polymer Complexes
Authors: Lee Joon Y. , Moskala Eric J. , Painter Paul C. , Coleman Michael M.
Published: July 2005

Intermolecular interactions play a major role in the mixing of two polymers. In certain cases, where these interactions are particularly strong, polymer complexes with simple stoichiometrics may be formed. Many polymer mixtures of this type are insoluble and infusible, which complicates simple transmission infrared studies. In this note we present preliminary results on studies performed on polyvinyl phenol) mixtures with poly(2-vinyl pyridine) using diffuse reflectance and conventional transmission infrared spectroscopies together with thermal analysis. Diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy appears particularly useful in studies of these polymer complexes.
Ligands with the “ONNN” Group as Chelating and Preconcentrating Substances of Heavy Metal Ions: Aroylhydrazone Derivatives from Di-2-Pyridyl Ketone
Authors: Garcia-Vargas M. , Belizón M. , Hernández-Artiga M. P. , Martinez C. , Pérez-Bustamante J. A.
Published: July 2005

The synthesis of the electronic and infrared spectra of di-2-pyridyl ketone salicyloylhydrazone (DPKSH) and di-2-pyridyl ketone benzoylhy-drazone (DPKBH) is reported. Ultraviolet absorption spectra have been applied for determining the dissociation constants: DPKSH, pK1 = 3.5 and pK2 = 6.85; DPKBH, pK1 = 2.75 and pK2 = 10.6. These pK a values are interpreted as a function of the ortho-position of the OH group. Chelating properties of both tridentate ligands have been investigated. DPKSH forms a larger number of metal chelates in acidic media than does DPKBH. Also, it is concluded that DPKSH is a more suitable compound than DPKBH to preconcentrate and to determine heavy metal ion traces as it is inferred from the data obtained by flame AAS.
Application of Fourier Self-Deconvolution to the FT-IR Spectra of Polydimethylsiloxane Oligomers for Determining Chain Length
Authors: Lipp Elmer D.
Published: July 2005

The resolution enhancement technique of Fourier self-deconvolution is applied to the FT-IR spectra of linear polydimethylsiloxane oligomers. A series of pure oligomers of known chain length is analyzed in regions characteristic of silicon-methyl modes in order to separate dimethyl from trimethyl contributions. Once separated, the relative size of the deconvoluted peaks can be quantitatively related to the chain length of the oligomers. This proves to be an effective means of obtaining chain length information from the infrared spectra and is applicable to oligomers having molecular weights up to 15,000.
Copper-Coated Cylindrical Internal Reflection Elements for Investigating Interfacial Phenomena
Authors: Iwaoka Teiki , Griffiths Peter R. , Kitasako John T. , Geesey Gill G.
Published: July 2005

Techniques for coating thin copper films on the surface of cylindrical germanium internal reflection elements are described. These films were then characterized in an aqueous environment. The expected exponential relationship between the depth of penetration of the evanescent wave into water and the thickness of the copper film was verified experimentally. The stability of vacuum-deposited copper coatings was strong enough that the internal reflection element could be exposed to an aqueous solution of a polysaccharide for more than 40 h. The weak adhesion of polysaccharides to copper surfaces was studied spectroscopically.
Infrared and Raman Spectra of 2,3-, 2,4-, and 2,5-Dimethylbenzonitriles
Authors: Sarma T. V. K.
Published: July 2005

The infrared and Raman spectra of 2,3-, 2,4-, and 2,5-dimethylbenzonitriles are recorded in the regions 400 to 4000 cm−1 and 100 to 4000 cm−1, respectively. Depolarization measurements are also undertaken. Assuming a C, point group for all the molecules, vibrational analysis is carried out. The frequencies of the umbrella vibration (mode 11) are calculated, and the calculated values agree very well with the observed values.
Laser-Enhanced Ionization Detection of Trace Elements in a Graphite Furnace
Authors: Magnusson I. , Axner O. , Lindgren I. , Rubinsztein-Dunlop H.
Published: July 2005

A graphite furnace is successfully used as an atomizer in laser-enhanced ionization spectroscopy (LEI). The physical origin of the signals is discussed and a comparison is made with LEI measurements in a flame. Extremely small amounts of analyte atoms can be detected using this method. The reproducibility is good, there are almost no memory effects, and the signal output is linear with the amount of analyte over at least 5 orders of magnitude. The experimental results indicate that the method could become an attractive alternative for trace-element analysis.
Analysis of Heat-Resistant Alloys by Inductively Coupled Plasma/Atomic Emission Spectrometry with Hydrofluoric Acid-Resistant Sample Introduction Systems
Authors: Kujirai Osamu , Yamada Kei , Kohri Muneyuki , Okochi Haruno
Published: July 2005

A simple and fast analytical method for complex Ni-based and Co-based heat-resistant alloys has been developed by inductively coupled plasma/atomic emission spectrometry (ICP-AES). Heat-resistant alloys of widely varying composition are dissolved in a mixture of hydrofluoric acid and nitric acid. A demountable hydrofluoric acid-resistant sample introduction system was used in which the surface of polytetrafluoroethylene (PTFE) parts was treated with metallic Na to improve the wetting property of the PTFE. Synthetic standard solutions are used for the calibration. Major and minor alloying elements are determined. The calibration curve method and internal standard method are compared. The internal standard method used two spectrometers and Mg as an internal standard element.
Electric Field FT-IR: Analysis of a Liquid Crystalline Polymer
Authors: Landreth B. M. , Stupp S. I.
Published: July 2005

Fourier transform infrared spectroscopy in a reflective mode has been utilized to study the dynamics of molecular structure in a polymeric liquid crystalline melt. The experimental setup included a thermo-electric cell which allows heating, melting of the sample, and also application of an electric ([Formula: see text]) field during spectroscopic observation. It was therefore possible to monitor orientation of dipolar groups as a function of time during thermal and electrical treatments. The material studied was a liquid crystalline copolyester, and orientation was monitored through absorbance associated with stretching of carbonyl bonds. Measurements taken on a melt of this material reveal an orientational response of carbonyl groups which begins immediately upon application of a relatively low [Formula: see text]-field (3750 V cm−1) and continues over a period of approximately one hour. It was somewhat surprising that a measurable change in dipolar orientation was observed. Cooperative dipolar phenomena and the torque-transmitting elasticity of the mesomorphic fluid are thought to be important factors in the observed behavior.
The Selection and Evaluation of Internal Standard Elements Based on Elemental/Instrumental Covariance
Authors: Bentley G. E. , Hamilton V. T. , Peterson E. J. , Wangen L. E.
Published: July 2005

The selection of internal standards for elements analyzed by a multielement direct-current argon plasma emission spectrometer was made by studying the elemental covariance of a multielement standard. Principal components factor analysis of many analytical determinations of this standard indicated that the elemental covariance clustered into two main groups. These groups were a function of instrumental variation, mainly plasma shape. The first principal factor accounted for 43.4% of the variance and had high loadings for strontium, barium, boron, manganese, nickel, titanium, silicon, calcium, and cadmium. The second principal factor accounted for an additional 36.7% of the variance and had high loadings for lithium, vanadium, magnesium, potassium, and aluminum. Compared with an external standard, internal standards dictated by the principal components factor analysis results gave improved precision. Internal standards not correlated with response variations degraded both the accuracy and the precision of the analysis.