bluuebunny/crossref_metadata_2025 huggingface dataset:
Infrared Intensities of Liquids. Part VII: Progress towards Calibration Standards
Authors: Bertie John E. , Keefe C. Dale , Jones R. Norman , Mantsch Henry H. , Moffatt Douglas J.
Published: July 2005

In 1961 the International Union of Pure and Applied Chemistry (IUPAC) formulated calibration standards for wavenumber measurements in the infrared, but comparable standards for infrared intensity measurements are still not available. In 1985 IUPAC established a Working Party on Secondary Standards for Intensity Measurements in Infrared Spectroscopy. This project is now at a stage where it is desirable to solicit advice and experimental support from a wider circle of spectroscopists in anticipation that a specific set of infrared intensity standards and calibration procedures could be formulated for measurements in the liquid phase. This paper outlines the background of these studies and reviews the present status of the project.
Impulse Photopyroelectric Depth Profiling of Multilayers. Part II: Experiments with Amplitude- and Phase-Modulated Wideband Spectrometry
Authors: Power J. F.
Published: July 2005

Impulse response photopyroelectric effect spectrometry (PPES) was implemented with the use of wideband excitation for the recovery of depth profiles of optical absorption in a series of multilayered thin-film polymer samples. The wideband PPES technique intensity modulates a cw laser beam with a waveform whose power spectrum is flat over the photothermal response bandwidth, enabling the recovery of the PPES impulse response (short pulse equivalent) by correlation and spectral analysis techniques. The impulse response measurement recovers a depth profile of subsurface optical absorption through the spatial dependence of the heat flux deposited in the sample by a short optical pulse. It shows excellent potential for use as a nondestructive evaluation tool in the analysis of polymers. The impulse response data recovered in this work could be accounted for by means of a theoretical model which neglected thermal reflections between the constituent sample layers. Absorption coefficient measurements on a single-layer sample were recovered through the time delay dependence of the PPES impulse response. The data were corrected for the effect of reflectivity at the thin-film pyroelectric detector surface, which significantly affects the time dependence of the impulse response. Several types of measurements were demonstrated on optically inhomogeneous samples. These included measurements of the thickness of transparent overlayers deposited on opaque substrates, depth-resolved spectroscopy, and techniques for improving multilayer contrast. The role of thermal wave reflections at the gas/solid interface was identified as a key factor in determining the depth profile contrast for subsurface spectral contributions, as well as the dependence of the impulse response on the thickness of nonabsorbing overlayers. Several approaches for optimizing photothermal depth profile contrast were demonstrated.
Fundamental Studies of Laser Ablation for the Introduction of Powdered Solid Samples into an Inductively Coupled Plasma
Authors: Furuta Naoki
Published: July 2005

Pelletized pond sediment was ablated by a pulsed Nd:YAG laser (0.35 J). The ablated material was swept into an inductively coupled plasma (ICP), and the emission spectra were measured by using a photodiode-array-based spectrometer. The mass transport efficiency was 35, 31, 25, and 21% for transport tubes that were 1.8, 3.2, 6, and 10 m long. With the use of a transport tube of 6 m, the pulse-to-pulse variation of the Mg(II) emission intensities at 279.6 and 280.3 nm was ∼30% as a relative standard deviation (RSD) of 12 measurements. It was found that the emission intensities were linearly related to the amount ablated. The precision for the Mg signals was improved to about 4%, if a steady-state signal was maintained by translation of the sample during repetitive shots of the laser and if Fe was used as an internal standard.
Near-Infrared Raman Spectroscopy with a Scanning Spectrometer
Authors: Engert C. , Michelis T. , Kiefer W.
Published: July 2005

This article shows that, by means of a conventional Raman spectrometer which has been carefully designed for near-IR Raman excitation, results can be obtained that are similar to those achieved with Fourier transform Raman instrumentation. We demonstrate the performance of such an apparatus on a variety of samples including examples of gaseous samples. As far as we know, up to now, no Raman spectra of gases have been published for excitation at 1064 nm. From a comparison of gas spectra excited at 1064 nm and 514 nm, we estimate the sensitivity of our apparatus to be at least three orders of magnitude lower than that for excitation in the green spectral region. Nevertheless, the main features in Raman spectra of gases can be recorded. High-performance solid-state spectra are compared with spectra recorded by means of FT techniques. They show superior sensitivity in the low-frequency range.
Rapid Detection of Bacterial Growth by Infrared Spectrophotometry
Authors: Iqbal Mohammad S. , Rashid Farooq
Published: July 2005

A rapid and sensitive method based on measurement of carbon dioxide released from a culture medium as a result of bacterial metabolism of glucose is reported. The rate of release of carbon dioxide was measured by recording the absorbance at 2353 cm−1 (4.25 μm) against time using a standard infrared spectrophotometer. Detection of growth from only five organisms of Salmonella typhosa was significant after just fifteen minutes. In about three hours a clear pattern of growth was obtained by this method. The results are reproducible with a standard deviation around ±0.5%.
A New Approach to the Investigation of Pre-Atomization Analyte Loss Mechanisms Occurring within a Graphite Furnace Atomizer
Authors: Rayson Gary D. , Johnson Clayton
Published: July 2005

A new method for probing the kinetics of analyte loss mechanisms occurring during the thermal pretreatment stage of analysis using graphite furnace atomic absorption spectrometry is described. The method involves the monitoring of the relative magnitude of the atomic absorption signal while systematically varying the pretreatment furnace temperature and time. The pre-atomization loss of Cu is discussed. The kinetics of the loss mechanism for Cu appear to be second order with an activation energy of 44 ± 6 kcal/mole.
Application of Laser-Enhanced Ionization to Flame Temperature Determination
Authors: Su King-Dow , Chen Chung-Yuan , Lin King-Chuen , Luh Wei-Tzou
Published: July 2005

We have both theoretically and experimentally demonstrated that the laser-enhanced ionization (LEI) technique can be a simple, alternative method for flame temperature determination in an atmospheric air/acetylene flame. A three-level model of rate equations is developed to determine a flame temperature based upon the Boltzmann population of the ground fine structures of the analyte selected. A Ga sample was used for the test, and the LEI signal was measured with excitation to various intermediate states. The determined flame temperatures are very consistent with each other and also with those previously reported.
Axial-Beam Absorption Detection for Capillary Electrophoresis with a Conventional Light Source
Authors: Xi Xiaobing , Yeung Edward S.
Published: July 2005

A commercial absorption detector was modified to provide axial-beam absorption detection for capillary electrophoresis. The increased pathlength led to improved detection limits. By the use of a nonaqueous solvent, the column is made into an optical waveguide for highly efficient light transmission. The electropherogram integrates the absorbance produced by all components in the sample, but provides information identical to that from normal electropherograms. The mechanical modifications make it possible to switch readily between the cross-beam and the axial-beam geometries.
In situ Evaluation of Diffusion Mechanisms in Thin Polystyrene Films Used as Integrated Optical Structures
Authors: Fell Nicholas F. , Bohn Paul W.
Published: July 2005

The use of optical waveguide techniques allows the in situ, nondestructive examination of diffusion in thin films. Through the eigenvalue equation, the changes in thickness and refractive index, corresponding to changes in the composition of the film, can be monitored. By assuming a Case-II-like sharp diffusion front, one can model the system as a two-layer film, whose individual layer thicknesses can be determined by the analysis of the observed eigenmodes. This model is used to judge the appropriateness of the Case II description for a given set of conditions. Thin films (on the order of 1–7 μm in thickness) of polystyrene were exposed to n-hexane, methylcyclopentane, and a mixture of the two. The analysis of the observed eigenmodes indicates that n-hexane diffuses into polystyrene via a Case II mechanism, but a Fickian leading edge of the diffusion front can also be observed. In general, this approach provides a simple technique to distinguish between Fickian and Case II diffusion in planar polymer films in the micron thickness regime.
Information-Based Expert Systems for Atomic Emission Spectroscopy
Authors: Pomeroy Robert S. , Kolczynski J. D. , Denton M. B.
Published: July 2005

The development of the direct-current plasma echelle/CID spectroscopic system for atomic emission spectroscopy (AES) provides new alternatives for automated system control and data analysis. With this system, the concept of the “intelligent” spectrometer becomes tangible. The echelle/CID system simultaneously gathers a wealth of spectral information over a wide spectral region. The mechanical stability of the system and the absence of moving parts give rise to reproducible wavelength assignment. The large amount of spectral information acquired has led to the development of information-based expert systems for AES: automated qualitative analysis, semi-quantitative analysis, and an “on the fly” matrix-dependent line selection. These algorithms are effective in situations where there is a large variability among samples. The analytical power of these routines is heavily dependent on their utilization of the large database and the use of fundamental spectroscopic principles. Examples of the use of these algorithms in environmental monitoring, in the identification of chemical waste, in the analysis of geologic materials and steels, and in HPLC-AES are presented.
The Use of a Near-Infrared Array Detector for Raman Spectroscopy beyond One Micron
Authors: Chase Bruce , Talmi Yair
Published: July 2005

The performance characteristics of a multielement Ge array detector have been measured. The effects of read noise and dark signal on signal integration have been evaluated. The performance of this array for Raman spectroscopy with excitation at one micron has been compared with FT-Raman spectroscopy. It is an excellent detector for narrow-spectral-bandwidth Raman studies, and the sensitivity compares favorably with that for FT-Raman techniques.
Interpreting IR Difference Spectra
Authors: Parry Diane B. , Samant Mahesh G. , Melroy Owen R.
Published: July 2005

From the evaluation of sample difference spectra based on Gaussian “model” peaks with known peak characteristics, it is shown that interpretation of some parameters from difference spectra, resulting from the ratioing or subtraction of a poor background spectra, may be inaccurate or misleading. Difference spectra of this type are commonly observed with the use of techniques such as subtractively normalized interfacial Fourier transform infrared spectroscopy (SNIFTIRS), electrochemically modulated infrared reflectance spectroscopy (EMIRS), or similar infrared spectroelectrochemical techniques, as well as some microsample analyses, studies of biochemical processes, and infrared astronomical observations, to name just a few examples. A mathematical evaluation of the problem is offered to demonstrate what information may realistically be gained from the characteristics of difference spectra. It is shown that in the worst case, where frequency, intensity, and peak width are all changing due to some perturbation of the sample (e.g., from temperature, or surface potential changes between background and sample spectra, etc.), even a qualitative interpretation may not be possible. In many practical cases, however, we show that at least a qualitative interpretation of the data can be obtained from difference spectra. Spectroelectrochemical applications for the calculations shown here are presented as examples, although these results impact a wider range of applications.
Detection of Trace Concentrations of Column III and V Hydrides by Laser-Induced Breakdown Spectroscopy
Authors: Cheng E. A. P. , Fraser R. D. , Eden J. G.
Published: July 2005

The measurement of trace concentrations (1-400 ppm) of polyatomic molecular impurities in helium was investigated by laser-induced breakdown spectroscopy (LIBS). For the Column III and V hydrides such as B2H6, PH6, and AsH3, the detectability limits with the present apparatus were determined to be 1, 3, and ∼1 ppm, respectively. It is expected that resorting to synchronous detection techniques will improve the sensitivity of LIBS for this application by as much as an order of magnitude.
Multicomponent Analysis of FT-IR Spectra
Authors: Saarinen Pekka , Kauppinen Jyrki
Published: July 2005

In multicomponent analysis we have the IR spectrum of an unknown mixture of gases, for which we have no knowledge of the constituent gases, not to mention their partial pressures. Instead we know a large set of library spectra of pure molecular gases, measured in known pressures and with the same interferometer as the unknown sample. By using these pure spectra we ought to be able to calculate the partial pressures of the pure gases in the mixture, with error limits. The errors in the obtained values arise from the measurement noise in the spectra. Because the calculation of such partial pressures that best explain the mixture spectrum is a relatively simple task, we shall consider it only briefly and will concentrate on the calculation of their error limits. We shall also consider the optimal choice for a resolution that will provide error limits as small as possible and the application of the non-negativity constraint for the partial pressures. In addition to gas spectra, all the calculations apply to spectra of noninteracting liquids as well.
Opticopyrometric Determination of Temperature in an Ar ICP
Authors: Strother R. E. , Bielski B. A. , Meeks F. R.
Published: July 2005

The temperature/spatial profile of an Ar ICP has been obtained by two-color infrared (IR) optical pyrometry. The temperatures range from 1668 to 2543 K, depending upon position and radio frequency (rf) input power. Results show at powers of 1.5 to 2.0 kW that the spatial dependence of the temperature closely resembles the spatial dependence of electron number density, suggesting that the electron number density plays an important role in determining the thermodynamic temperature.
Fluorescence Lifetime Imaging: An Approach for Fuel Equivalence Ratio Imaging
Authors: Ni Tuqiang , Melton Lynn A.
Published: July 2005

This paper describes dopants, apparatus, and procedures which can be used for planar laser-induced fluorescence (PLIF) imaging of the fuel/oxygen equivalence ratio, the most important mixture parameter in combustion studies. The lifetime imaging techniques described here provide data beyond the data available from conventional intensity imaging, and should allow the equivalence ratio to be determined in real time in a two-dimensional slice of a fuel spray. Lifetime imaging methods require the sequential gating of two 2-D detectors during the fluorescence decay. Proof-of-concept experiments indicate that lifetimes ranging from 5 to 50 ns can be imaged with good accuracy. The requirements for fluorescent dopants and considerations for use under flame conditions are also discussed.
Fast Collection Times for Fluorescence-Decay Measurements
Authors: Nowak Steven A. , Basile Franco , Kivi Jeffrey T. , Lytle Fred E.
Published: July 2005

Acquisition times as short as 10 ms are achieved for the collection of fluorescent decays with a time-correlated single-photon counting detection scheme, arranged in the reverse-interactive configuration, and high-repetition-rate laser excitation. Faster acquisition times for the measurement of fluorescent decays are accomplished by employing the same laser excitation system and photomultiplier anode-current sampling with a digital oscilloscope. With this variant, an 8.9 ns exponential decay is collected in 8.058 μs.
Improvement of the Limiting Thickness of the Measurable Surface Layer on Polymer Films Using Fourier Transform Infrared Attenuated Total Reflection Spectroscopy with the Use of Silver Island Films
Authors: Nishikawa Yuji , Ito Yoshiaki , Fujiwara Kunihiro , Shima Tetsuo
Published: July 2005

Improvement in the detection limit of the surface layer on polymer films has been demonstrated with the use of Ag films under Kretschmann's attenuated total reflection (ATR) geometry. A remarkable absorption enhancement for 2.5-nm-thick polydimethylsiloxane (PDMS) or for 4.0-nm-thick polycarbonate (PC) coated on polyethyleneterephthalate (PET) films was observed. The magnitude of the enhancement factor is 10 for PDMS and 2 for PC compared with results for the conventional ATR method. In the case of PDMS, the limiting thickness of the measurable surface layer is about 0.5 nm with the use of the spectral subtraction technique. The correlation between the difference in the enhancement factor and the enhancement mechanism is also discussed.
A Study on the Qualitative and Quantitative Analysis of Nanogram Samples by Transmission Infrared Spectroscopy with the Use of Silver Island Films
Authors: Nishikawa Yuji , Fujiwara Kunihiro , Shima Tetsuo
Published: July 2005

Qualitative and quantitative analysis of nanogram amounts of substances by transmission infrared spectroscopy with the use of silver island films was carried out. The effect of silver thickness, the comparison of several plates (Ge, BaF2, and ZnSe), the dynamic range of intensity enhancement vs. sample amount, and the enhancement stability after sample deposition were investigated extensively to determine the optimum conditions. The limits of detection (LOD) of several substances were also described. LOD values ranging from 5 ng/cm2 for polydimethylsiloxane to 10 ng/cm2 for diethylphthalate were obtained, and these values show a remarkable improvement in LOD in comparison with results from normal transmission spectroscopy. A quantitative study was also undertaken. A good linear relationship with respect to the amount of triphenyl phosphate, ranging from 25 to 250 ng/cm2, was obtained. The data were reproducible with a coefficient of variation of 15%, and this variation was comparable to that obtained with several surface-enhanced Raman scattering methods.
Laser-Induced Fluorescence Detection of Rhodamine-6G at 6 × 10−15 M
Authors: Hahn Jong Hoon , Soper Steven A. , Nutter Harvey L. , Martin John C. , Jett James H. , Keller Richard A.
Published: July 2005

We have demonstrated sensitive fluorescence detection of rhodamine-6G in aqueous solutions down to ∼10−15 M with a detection limit of 6 × 10−15 M. The working curve was observed to be linear over four orders of magnitude and could be extended to higher concentrations. Single molecules of rhodamine-6G had a transit time of 1.8 ms through the 11 pL probe volume. At 2 × 10−14 M, the probability of a molecule being in the 11 pL probe volume is ∼0.1. Analysis of the data indicates that the signal-to-noise ratio for the detection of a single molecule of rhodamine-6G is ∼1.
Photoacoustic Enhancement of Surface IR Modes in Zeolite Channels
Authors: Wang H. Paul , Eyring Edward M. , Huai Huaying
Published: July 2005

The photoacoustic (PA) signal enhancement of an infrared-active mode of the adsorbed pyridine in the channel/cage of zeolites HZSM-5 and HY was studied comparatively with the use of photoacoustic, transmittance, and diffuse reflectance FT-IR spectroscopies. The data indicate that the PA enhancements of an infrared band of the adsorbed pyridine in the channel/cage of HY and HZSM-5 are 2.1 and 3.3, respectively. The importance of interstitial gas expansion in the photoacoustic signal enhancement of the surface infrared mode is discussed.
A High-Temperature Oven for Laser Spectroscopy
Authors: Wang Zheng-Min , Weeks S. J. , Edelson M. C.
Published: July 2005

A commercial heat-pipe oven (HPO) was modified to extend the useful temperature range from 700°C to ∼1700°C. The utility of the modified heat pipe oven as an atom source for spectroscopy is demonstrated with a laser atomic absorption study of the hyperfine splitting of Tm (m.p. 1545°C).
Surface-Enhanced Raman Scattering (SERS) Study on the Air Oxidation of Copper and its Reactions with Azoles
Authors: Xue Gi , Zhang Junfeng
Published: July 2005

Surface-Enhanced Raman Scattering (SERS) on HNO3-roughened copper foils has been used to follow the air oxidation of copper at room temperature and to study the surface reactions with azole compounds. It has been found that azoles react with metallic copper as well as copper oxides. SERS and IR studies show that the reaction of azoles with metallic copper is faster than with cuprous and cupric oxides.
Determination of the Degree of Nitration of Cellulose Nitrates via GPC/FT-IR Using an On-Line Flow Cell
Authors: Saunders C. William , Taylor Larry T.
Published: July 2005

On-line Gel Permeation Chromatography/Fourier Transform Infrared (GPC/FT-IR) spectroscopy has been used to develop a method for the determination of the nitrogen content of cellulose nitrates. The method is based upon the solution infrared spectrum of the cellulose derivative in tetrahydrofuran. Making use of the second derivative of the spectra, wherein antisymmetric ONO stretches for both primary and secondary carbon nitration are discernible, has eliminated the relative concentration dependence of the absorption. This feature has permitted the determination of the nitrogen content of cellulose nitrates throughout their molecular weight distribution.
Fourier Transform Infrared Spectroscopy of Nitric Oxide during Exposure to Vacuum Ultraviolet Radiation
Authors: McNesby K. L. , Fifer R. A.
Published: July 2005

The FT-IR spectrum of chemically pure (C.P.) NO was obtained while the gas was being irradiated by radiation at 121.5 nm. A novel cell design allows the ultraviolet radiation and the infrared probe beam to be co-linear. The exposure time of the gas to the UV radiation ranged from 0 to 100 minutes. Spectra were collected at evenly spaced time intervals during irradiation by the UV radiation. The composition of the gas changed as a function of irradiation time. Experimental results were compared with the calculated change in the composition of the gas by solving a set of simultaneous differential equations based on a kinetic model, giving good agreement. It is shown that the cell may also be used as an actinometer, and may be used as a check on the applicability of some rate equations to reacting systems.
A Comparative Study of NIR Diffuse Reflectance of Cottons Grouped According to Fiber Cross-Sectional Dimensions. Part III: Experimental
Authors: Montalvo Joseph G. , Faught Sherman E. , Buco Steven M.
Published: July 2005

In Part I of this series, a model was proposed to predict the comparative NIR reflectance of grouped cottons. In Part II of this series, the model's optical path was simulated. We report here the detailed examination of this model, its optical path, and cotton reflectance spectra in the wavelength range from 840 to 2500 nm. The premise that paired cottons with allowed nontrivial combinations of dimensional variables will produce the predicted comparative reflectance is verified experimentally, as is the premise that any number of cottons of the same perimeter with varying wall thickness will produce the predicted comparative reflectance. The critical assumption of a constant total fiber length in the optical path, for cottons of the same perimeter, is confirmed. Thus the log(1/ R) values are a function of a wall dimension (thickness or area) and perimeter. Finally, three distinct wavelength regions of the reflectance spectra are noted: <1440 nm, 1440 to 2100 nm, and ≥2100 nm. At wavelengths ≥ 2100 nm, significant absorption of photons out of the beam, caused by the cellulose in the fiber wall, controls the reflectance. At wavelengths <1440 nm, the log(1/ R) function is different and its cause unresolved. For some cottons, the intermediate band of wavelengths shows a transition in log(1/ R) values from the resolved to the unresolved function.
Mueller Calculus Spectrometric Simulations of Thermal Lensing
Authors: Voigtman Edward
Published: July 2005

A commercially available microcomputer-based simulation program, augmented with more than 130 custom-programmed component blocks, has been shown to allow the seamless integration of both optical and signal processing components on a computer screen worksheet. The libraries of custom component blocks allow scientific block diagrams, representing a variety of spectrometric techniques, to be “brought to life” as functional technique simulations. The libraries of blocks are applied to the qualitative and quantitative modeling of several published thermal lensing instruments, with the achievement of excellent results.
Interaction of Silanol Species on Silica Surface with Hydrogen Bonding Agents Studied by Photoacoustic Spectroscopy
Authors: Pandurangi Raghoottama S. , Seehra Mohindar S.
Published: July 2005

The interaction of amorphous silica particles with several hydrogen bonding agents (H2O, C2H5OH, C7H8NO) was investigated by monitoring the changes in the bulk and surface IR vibrational modes of silica using photoacoustic spectroscopy. It is argued that the intensity of the silanol band at 3747 cm−1 provides (an inverse) quantitative measure of the interaction of surface groups, along with the shift in the broad hydroxyl band, the interaction following the order C7H8NO > C2H5OH > H2O.
Spectroscopic Studies of Oxidized Soots
Authors: Akhter M. S. , Chughtai A. R. , Smith D. M.
Published: July 2005

Vibrational spectroscopy, ESCA, and C-13 CP/MAS NMR provide a detailed picture of the structure, and therefore reactivity, of the products of the reactions of soot with various oxidants. Reactions such as soot-NO2/N2O4, soot-O3, and soot-SO2, at atmospheric and sub-atmospheric pressures, and at different temperatures, have been studied. The reaction between NO2/N2O4 and n-hexane soot is rapid near room temperature, yielding several surface species, including C-NO2, C-ONO, and C-N-NO2. These functionalities have been confirmed through reaction with 15NO2 and N−18O2. The oxidation of SO2 in soot-SO2 systems yields ionic sulfate, confirmed by isotopic substitution, and requires the presence of water vapor and oxygen. The presence of simulated solar radiation in the same system results in the formation of both ionic and covalent sulfate species. The spectroscopic measurements show carboxyl surface species formed during the soot-ozone reaction. The use of FT-IR, ESCA, and C-13 CP/MAS NMR has yielded consistent results for these carbonaceous particulates in each reaction, but the vibrational spectroscopy is easily the most definitive with such systems.
Infrared Studies of Wood Weathering. Part II: Hardwoods
Authors: Anderson Erin L. , Pawlak Zenon , Owen Noel L. , Feist William C.
Published: July 2005

Four different hardwoods—yellow poplar, quaking aspen, white oak, and hard maple—have been subjected to a range of artificial weathering conditions, and their surfaces monitored with the use of diffuse reflectance infrared spectroscopy. The first two species show a weathering pattern rather similar to that of softwoods, whereas the latter two are more resistant to the effects of light and water. The differences in wood density are thought to be significant in the different behavior of the woods towards weathering, in addition to any contributing effects that might be caused by a variation in the overall chemical composition. After 2400 hours of full artificial weathering, all traces of lignin seem to have been removed from the surfaces of all four woods.
Kinetic Aspects in Solid-Matrix Luminescence for Lumiphors Adsorbed on Filter Paper
Authors: Hurtubise R. J. , Ramasamy S. M.
Published: July 2005

From the room-temperature fluorescence lifetimes of benzo(f)quinoline and 4-phenylphenol adsorbed on filter paper and earlier luminescence data, several photophysical parameters were calculated. Also, a number of equations that relate radiative and nonradiative rate constants to pre-exponential factors and activation energy terms were considered. By combining the luminescence data obtained in this work and previous luminescence data acquired as a function of temperature, it was possible to derive equations for the two model compounds that described fluorescence quantum yield and phosphorescence quantum yield as a function of the pre-exponential factors, activation energies, and temperature. These equations were somewhat complex, but some fundamental conclusions were revealed after a few simplifying assumptions were made.
Fluorescence Pattern Analysis Based on the Time-Resolved Ratio Method
Authors: Wang Xue Feng , Uchida Teruo , Maeshima Muneo , Minami Shigeo
Published: July 2005

A new technique is described for component pattern analysis based on time-resolved fluorescence image detection and a ratio method calculation. Differences in fluorescence lifetimes of components are positively utilized to estimate the spatial distribution of each component. Simulation results of the ratio method for fluorescence pattern analysis are discussed. Spatial deconvolution of multicomponent fluorescence data is rapidly carried out from a set of time-resolved, two-dimensional fluorescence data. An example of the application of a multigate time-resolved ratio method for fluorescence pattern analysis is provided. From the results, it is shown that the new method can be successfully used for multicomponent fluorescence pattern analysis at a reasonable signal-to-noise ratio.
EDXRF Studies of the Nanking Cargo with Principal Component Analysis of Trace Elements
Authors: Yap C. T.
Published: July 2005

The energy-dispersive x-ray fluorescence technique was applied to the study of 30 pieces of Chinese porcelains from the Nanking Cargo and 4 pieces of modern fakes. Analysis showed that the Nanking Chinese porcelains were made in Jingdezhen, the porcelain city of China. Principal component analysis was applied to the measured concentrations of 10 elements (Fe, Ni, Cu, Zn, As, Rb, Sr, Y, Zr, and Nb). It was found that such analysis could discriminate between the various elements as being useful and not useful variables. It was also found that the glaze used for the base regions was rather different from the glaze used for other regions, a practice which existed during the Qing dynasty (1644–1911) but is not carried out nowadays.
Glow-Discharge Atomic Emission Spectrometry with a Spectrally Segmented Photodiode-Array Spectrometer
Authors: Brushwyler K. R. , Hieftje G. M.
Published: July 2005

A spectrally segmented photodiode array (PDA) atomic emission spectrometer (AES) is used to monitor emission from a glow-discharge source (GDS) equipped with an electrically floating restrictor tube (internal diameter: 8 mm) and operated at 110–225 W/cm2 and 400–600 Pa argon pressure. The PDA spectrometer is capable of performing simultaneous multielement determinations over a wide spectral range (200–400 nm) while maintaining sufficient spectral resolution (∼10 pm full width at half-maximum) for AES. Emission spectra from the GDS are compared with those from an inductively coupled plasma (ICP). Although GDS emission spectra showed very low levels of background continuum, they were much more cluttered than spectra obtained from an ICP. Stepwise multiple linear regression (MLR) was useful in the analysis of the complex GDS emission spectra and was used to simplify the identification of unknown spectral peaks and spectral interferences. Ordinarily, correcting such problems is difficult with a GDS because of its complex emission spectrum and the inability to obtain true GDS blank spectra. Optimized optical masks for the PDA spectrometer were designed for the GDS analysis of low-alloy steel. Because no systematic attempt was made to optimize the GDS, detection limits were found to be approximately ten times higher than typical values reported for multichannel photomultiplier-based spectrometers.
Proton NMR Analysis of Octane Number for Motor Gasoline
Authors: Ichikawa M. , Nonaka N. , Amano H. , Takada I. , Ishimori S.
Published: July 2005

A method to assess the octane number of motor gasoline by proton magnetic resonance (PMR) spectrometry was studied. Twenty-eight kinds of regular gasoline and 24 of premium gasoline were sampled from the market from winter to summer, and their PMR spectra were classified by a supervised learning pattern recognition method, an unsupervised learning pattern recognition method, and other related methods. This report concerns a successful attempt to identify regular and premium gasoline by PMR spectrometry.
Colorimetric pH Determination with Computer Modeling
Authors: Baumann E. W. , Buchanan B. R.
Published: July 2005

A colorimetric method with azoviolet indicator was developed to determine pH of concentrated waste solutions with pH >11. Experimental data with calibration solutions in 4 M NaNO3 were modeled two ways. A single-wavelength quadratic model was made with the peak wavelength at 554 nm. A more elaborate model with spectral data from 400 to 650 nm used a polynomial fit to the ratio of the PLS eigenvalues. For both models, the data were normalized and made independent of indicator concentration through division by the sample absorbance at the isosbestic point. Both models showed a precision of fit of ±0.1 pH unit in solutions that contained 3 to 4 M NaNO3. However, the full-spectrum model was able to flag inappropriate samples through goodness of fit calculations.
Quantitative Elemental Analysis of Iron Ore by Laser-Induced Breakdown Spectroscopy
Authors: Grant Kenneth J. , Paul George L. , O'Neill James A.
Published: July 2005

Results are presented of the elemental analysis of iron ore using laser-induced breakdown spectroscopy (LIBS). Calibration curves for calcium, silicon, magnesium, aluminium, and titanium were produced. The precision ranges from ≈2 to ≈25%. The detection limits are element-dependent, but are of the order of 0.01%. The extension of LIBS from the laboratory to a field-based analytical technique is discussed.
Doppler-Free Spectrum of the Barium 1S0−1P1 Transition by Degenerate Four-Wave Mixing Using an Air/Acetylene Flame
Authors: Andrews John M. , Weed Kenneth M. , Tong William G.
Published: July 2005

Doppler-free flame spectrometry based on resonant degenerate four-wave mixing (D4WM) is shown to be an effective analytical tool for the determination of barium at high spectral resolution. Optical phase conjugation is produced in an air/acetylene flame, resulting in an optical signal that is a coherent time-reversed replica of the probe beam. The degenerate four-wave mixing spectrum of barium for the 6 s21 S0-6 s6 p1 P1 transition at 18,060.19 cm−1 is collected with a linewidth of 0.08 cm−1 (FWHM) with the use of a convenient continuously flowing atmospheric-pressure flame atomizer. A preliminary detection limit of 5 μg/mL barium, while a Doppler-free linewidth is maintained at 0.08 cm−1, is reported.
Isolation and Identification of Potential Migrants in Gamma-Irradiated Plastic Laminates by Using GC/MS and GC/IR
Authors: Kim-Kang Heasook , Gilbert Seymour G.
Published: July 2005

Potential migrants were isolated by Soxhlet extraction from plastic laminates of PETG/PVDC/PE used to make a single-use injection system. Most of compounds were identified from mass spectra by comparison to reference spectra. However, reference spectra were not available for several major compounds in the Soxhlet extract from irradiated test laminates. Those unknown compounds were identified by using both GC/IR and GC/MS. The change in polymer structure due to irradiation was also monitored by using Fourier transform infrared spectroscopy.
Evaluation of Absolute Number Densities by Diode Laser Atomic Absorption Spectroscopy
Authors: Barber T. E. , Walters P. E. , Winefordner J. D. , Omenetto N.
Published: July 2005

A simple method of evaluating absolute number densities in atom reservoirs is described. It consists of measuring the difference in the integrated absorption signals obtained from a reference cell and an analytical cell with a frequency-modulated diode laser as primary source. The evaluation of the number density of atoms in the analytical cell is straightforward and, in optically thin conditions both in the vapor cell and in th analytical cell, does not even require the knowledge of the absorption oscillator strength of the transition. Conversely, for a given, known value of the atomic density, the number density in the analytical cell can be obtained.
Infrared Study of Factors Affecting the Emissivity of Aluminum
Authors: Guthrie J. D. , Sparr B. J.
Published: July 2005

Temperature measurement of aluminum surfaces by remote sensing of infrared radiation (pyrometry) is difficult due to the low and varying emissivity of aluminum. The emissivity of 1199 aluminum and 3004 and 5182 alloys was studied as a function of oxide level, surface roughness, temperature, and wavelength. Factorial analysis showed that oxide level and temperature were the major effects for the 1199 aluminum and 3004 alloy, while surface roughness and temperature were the major effects for the 5182 alloy. The emissivity curves indicated that the samples behave as grey bodies, except for samples with thick, high-temperature oxides, which exhibit metal oxide absorption bands in the 10–20 μm region of the emissivity curves. Repeatability in temperature measurement by pyrometry as a function of alloy was also studied. Alloy 5182 showed the greatest variability, followed by 3004 and 1199.
Design and Characterization of an Echelle Spectrometer for Fundamental and Applied Emission Spectrochemical Analysis
Authors: Scheeline Alexander , Bye Cheryl A. , Miller Duane L. , Rynders Steven W. , Owen R. Calvin
Published: July 2005

An echelle spectrometer has been constructed, which is optimized for use with a charge-coupled array detector, with dispersion and resolution appropriate for elemental analysis and plasma diagnostics. Design considerations, characterization, software, and initial experimental data are reported.
Fourier Transform Raman Spectroscopy Using a Tuneable Solid-State Laser and a Semiconductor Bandgap Filter
Authors: Schulte A. , Lenk T. J. , Hallmark V. M. , Rabolt J. F.
Published: July 2005

The feasibility of using the optical absorption properties of a semiconductor crystal as a long wavelength pass filter for Fourier transform Raman spectroscopy applications has been demonstrated. Near-infrared excitation from a titanium: sapphire solid-state laser was selectively tuned to the edge of the bandgap absorption of an indium-doped cadmium telluride semiconductor filter. Raman spectra to within 30 cm−1 of the exciting line could be measured. Narrowing of the optical absorption of the semiconductor filter at low temperatures did not improve the “sharpness” of the cutoff performance.
Selective-Ultratrace Detection of Metal Ions with SERS
Authors: Carron Keith , Mullen Ken , Lanouette Mark , Angersbach Helena
Published: July 2005

We report the results from experiments involving the detection of metal ions with a Surface-Enhanced Raman Spectroscopic indicator (SERS indicator). Comparisons of metals showed that the SERS effect can be used to selectively detect metal ions according to their ionic radius. We determined a resolving power for separating the alkaline earth series. The results indicate that the resolving power of the SERS approach is superior to that of absorption spectroscopy. Quantitatively, under our experimental conditions, we found a detection limit of 270 ppb for Pb2+ and 85 ppb for Cu2+ with the indicator Eriochrome Black T.
A Vacuum Ultraviolet, Supersonic Jet Absorption Spectrometer
Authors: Fournier E. W. , Hertz R. A. , Steadman J. , Cohen R. B. , Syage J. A.
Published: July 2005

A technique for recording high-resolution, broadly tunable absorption spectra in the ultraviolet (UV) and vacuum ultraviolet (VUV) is described. A supersonic expansion is used to prepare molecules in a rovibrationally cold distribution of states, and a dispersed broad-band deuterium (D2) lamp is used for excitation. The attenuation of light due to absorption is measured with the use of dual gate detection during pulsed valve-on and valve-off periods. The VUV light beam, after crossing the supersonic expansion, is frequency down-converted with a scintillator-coated exit window, and the resulting light intensity is measured by boxcar integration or photon counting. A simple sample delivery system and complete software control of the experiment make this system a routine laboratory spectrometer. Sensitivity and resolution are discussed, and the device is demonstrated for the molecules NH3 and CH3I.
A New Line-Narrowing Procedure Based on Fourier Self-Deconvolution, Maximum Entropy, and Linear Prediction
Authors: Kauppinen J. K. , Moffatt D. J. , Hollberg M. R. , Mantsch H. H.
Published: July 2005

We propose a new methodology to reduce the widths of spectral lines. This procedure, which is performed entirely in the time domain, combines elements of the methods of Fourier Self-Deconvolution (FSD), Maximum Entropy (MEM), and Linear Prediction (LP) in such a way as to take advantage of the efficacies of each of these procedures. The procedure is illustrated with examples.
A Two-Dimensional Fluorescence Lifetime Imaging System Using a Gated Image Intensifier
Authors: Wang Xue Feng , Uchida Teruo , Coleman David M. , Minami Shigeo
Published: July 2005

A simple fluorescence lifetime imaging system using a gated micro-channel plate (MCP) image intensifier coupled to a CCD camera has been developed. Nanosecond-level time-resolved fluorescence images of a sample under a pulsed light excitation can be detected directly. With a rapid lifetime determination method for multigate detection, fluorescence lifetime imaging can be promptly performed. In the present system, laser excitation of sample and shutter action of an image intensifier are fully synchronized by means of an optical fiber delay line. In order to compensate for fluctuations in the excitation source, a simple intensity monitor circuit was developed. Details of the instrumental system and verification measurements on two component samples are presented.
Interaction of a Laser Beam with Metals. Part I: Quantitative Studies of Plasma Emission
Authors: Hwang Zen-Wen , Teng Ye-Yung , Li Kuang-Pang , Sneddon Joseph
Published: July 2005

Quantitative plasma power emission measurements of the effect of increasing laser energy for the interaction of a 193-nm wavelength laser on four selected metals are presented. A correlation between a theoretical model for mass vaporized and increasing laser energy intensity was found for the selected metals.
Polarization Modulation FT-IR Spectroscopy of Surfaces and Ultra-Thin Films: Experimental Procedure and Quantitative Analysis
Authors: Buffeteau T. , Desbat B. , Turlet J. M.
Published: July 2005

Polarization modulation of the incident electromagnetic field is used to increase the sensitivity and the in situ experiment ability of the well-known method of reflexion absorption FT-IR spectroscopy, for the characterization of surfaces and ultra-thin films. The experimental procedure and signal processing of the detected intensity are described and illustrated with the use of results obtained with Langmuir-Blodgett monolayers. The quantitative analysis of the spectra is then developed, and a linear behavior of the band intensities is found for ultra-thin films exhibiting no strong absorptions. This result is checked with the use of organic and inorganic ultra-thin films of increasing thicknesses.
The Use of Fourier Self-Deconvolution for Determining Vapor Band Contours from Low-Resolution (GC/IR) Infrared Spectra
Authors: Jakobsen R. J. , Lyons-Hart J. , Southwick E.
Published: July 2005

Vapor band contours have been derived from low-resolution (GC/IR) infrared spectra of methylpyrazine and 2,6-dimethylpyrazine by applying Fourier self-deconvolution techniques to the GC/IR spectral data. The vapor band contours obtained in this manner show good agreement with vapor band contours observed in high-resolution spectra.
Excitation Temperatures and Electron Densities in a Magnetron Rotating Direct-Current Arc Plasma
Authors: Slinkman David , Sacks Richard
Published: July 2005

Excitation temperatures and electron densities are reported for a magnetron rotating direct-current arc plasma with graphite furnace sample introduction. Temperatures obtained from emission line ratios of the Ar support gas are compared with values obtained for two analyte thermometric species, Zn(I) and Cu(I). At the anode surface, the plasma temperature is about 6500 K. The addition of an easily ionized element does not effect the Ar(I) temperature; however, a temperature increase of up to 1000 K was observed for the analyte thermometric species. At the anode surface, the electron density is about 1.0 × 1015 cm−3. The addition of an easily ionized element increases the electron density by about a factor of two. Possible explanations are given for the increases in temperature and electron density.
Quantitative Determination of Sugar Cane Sucrose by Multidimensional Statistical Analysis of Their Mid-Infrared Attenuated Total Reflectance Spectra
Authors: Cadet Frédéric , Bertrand Dominique , Robert Paul , Maillot Joseph , Dieudonné Jules , Rouch Claude
Published: July 2005

A fast and accurate method for determining the sucrose content of sugar cane juice has been developed. The application of principal component regression (PCR) has been proposed for the development of a prediction equation of sucrose content by mid-infrared spectroscopy. An attenuated total reflectance (ATR) cell is used in place of the more familiar transmission cell. PCR involves two steps: (1) the creation of new synthetic variables by principal component analysis (PCA) of spectral data, and (2) multiple linear regression (MLR) with these new variables. Results obtained by this procedure have been compared with those obtained by the conventional application of polarization.
Spatially Resolved Adsorption Kinetics of Immunoglobulin G onto the Wettability Gradient Surface
Authors: Hlady Vladimir
Published: July 2005

Total internal reflection fluorescence (TIRF) was combined with charge-coupled-device (CCD) photon detection in measuring spatially resolved protein adsorption kinetics along one of the linear dimensions of a flat surface. The experimental method was designed to study the kinetics of binding of fluorescein-labeled immunoglobulin G (FITC-IgG) onto the surfaces with the wettability gradient. Protein was adsorbed from a flowing buffer solution. The buffer solution contained either only fluorescein-labeled immunoglobulin G or FITC-IgG and two other unlabeled proteins: albumin and fibrinogen. The concentrations of proteins were 1/1000 of the respective protein concentrations in plasma. Adsorption of FITC-IgG was dependent on the wettability of the surface as well as on the presence of other proteins in the adsorbing solution. The exchange of surface-bound FITC-IgG with other proteins was observed along the wettability transition region of the gradient surface but not at either the hydrophobic or the hydrophilic sides. The amphiphilic interface between the microscopic hydrophobic and hydrophilic domains in the wettability transition region of the gradient surface was proposed to explain the adsorption behavior of FITC-IgG. The spatially resolved TIRF-CCD method has the potential of detecting the fast protein adsorption, desorption, and exchange processes from complex protein mixtures, such as serum and plasma.