bluuebunny/crossref_metadata_2025 huggingface dataset:
Nanosecond Two-Dimensional Resonance Raman Correlation Spectroscopy of Benzil Radical Anion
Authors: Ebihara Ken , Takahashi Hiroaki , Noda Isao
Published: June 2005

Nanosecond two-dimensional resonance Raman spectroscopy was used to investigate the photochemistry of the production and decay of the radical anion of benzil in various solvents. A newly developed correlation formalism was applied to a set of time-resolved resonance Raman spectra of the benzil radical anion to generate two-dimensional Raman spectra. Unlike the 2D correlation method previously developed for IR spectroscopy, which was based on signals induced by a sinusoidally varying external perturbation, the new correlation formalism is generally applicable to the studies of any transient spectroscopic signals having an arbitrary waveform. This makes it ideally suited for the analysis of time-resolved spectroscopic signals following photoexcitation. 2D Raman spectra effectively accentuate certain useful information which is sometimes obscured in the original time-resolved spectra. Spectral intensity changes and peak shifts arising from the photochemical reaction processes were clearly observed by the synchronous and asynchronous correlation.
Toward Theorectical Limits of FT-IR Microspectroscopy for Ultra-Thin Organic Layers
Authors: Mizaikoff B. , Taga K. , Kellner R.
Published: June 2005

In this work the influence of the substrate geometry on FT-IR microspectroscopical transmission measurements is reported with special emphasis on the impact on the lateral resolution. Mid-infrared transparent fibers (chalcogenide glass) and even substrates (zinc selenide ATR crystal) were sprayed with drops (drop size distribution: 15 to 150 μm in diameter) of an organic polymer with specific absorption bands in the mid-infrared range. Quadratic scans along the surface of the fiber and of the even substrate gave information about whether the drops distributed on the surface appear laterally resolved, by maintaining the local information in the resulting contour plot. Several scans with different microscopic apertures accentuate the relation between the diameter of the focused IR beam on the sample surface and the broadening of the drop image in the contour plot.
New IR Fiber-Optic Chemical Sensor for in Situ Measurements of Chlorinated Hydrocarbons in Water
Authors: Krska R. , Taga K. , Kellner R.
Published: June 2005

In this work the development and validation of a new MIR fiber-optic physicochemical sensor system for the continuous in situ analysis of chlorinated hydrocarbons (CHCs) in water is described. This study took advantage of the selectivity and sensitivity of fiber evanescent wave spectroscopy (FEWS) and the recent development of polycrystalline silver halide fibers. Since these fibers are transparent up to 20 μm, it was possible for the first time to develop a fiber-optic sensing system for CHCs, which have their strongest absorption bands > 10 μm. The silver halide fibers were coated with low-density polyethylene (LDPE) to enrich the CHC within the evanescent wave and to exclude the IR absorbing water from the measurement. For the quantitative in situ FEWS measurements, the coated silver halide fibers were coupled to a Fourier transform infrared (FT-IR) spectrometer using an off-axis parabolic mirror and a fiber-detector coupling system. This setup enabled the simultaneous in situ detection of the most common chlorinated hydrocarbons in concentrations between 1 to 50 mg/L in water by employing a fiber sensing part only 10 cm in length. A comparative analysis of waste water samples under participation of two experienced head space-gas chromatography (HSGC) laboratories showed good agreement of this continuous sensor system with the established standard techniques. The resulting working curve for tetrachloroethylene showed a correlation coefficient of r2 = 0.968 and a relative standard deviation of 17% in the range from 1 to 10 ppm.
Dynamic Analysis of Polymer-Dispersed Liquid Crystal by Infrared Spectroscopy
Authors: Hasegawa Ray , Sakamoto Masanori , Sasaki Hideyuki
Published: June 2005

The dynamic behavior of a polymer-dispersed liquid crystal (PDLC) under an electric field has been studied by static and two-dimensional infrared spectroscopy. The PDLC sample was prepared by polymerization-induced phase separation of a mixture of nematic liquid crystal E7 and acrylate. 2D IR correlation analysis indicates that the rigid core of the liquid crystal molecules reorients as a unit, and suggests that the polymer side chain existing in the interface between the polymer and the liquid crystals may reorient in phase with the liquid crystal reorientation by interaction with the liquid crystal molecules.
Conformational Ordering Process on Physical Gelation of Syndiotactic Polystyrene/Solvent Systems Revealed by Time-Resolved Infrared Spectroscopy
Authors: Kobayashi Masamichi , Kozasa Takehito
Published: June 2005

Syndiotactic polystyrene (SPS) dissolved in various organic solvents forms stable gels. Infrared spectroscopic research shows that SPS molecules assume highly ordered TTGG conformation in gels, giving rise to many infrared bands characteristic of the regular TTGG sequences. The behavior of the conformational ordering is strongly dependent on the solvent and the temperature. The time evolution of the conformational order on gelation has been investigated for SPS/CHCl3 systems at various polymer concentrations and temperatures by time-resolved infrared spectroscopy. By the analysis of the rate of formation of the ordered conformation derived from the time-resolved intensity measurement of the conformation-sensitive band at 572 cm−1, the number of the chain segments that contribute to the formation of clusters having ordered TTGG conformation has been evaluated as a function of temperature. The results indicate that at a temperature around 10°C the conformation ordering proceeds through clustering of five chain segments. The number decreases with lowering temperature and becomes unity below a certain temperature, suggesting that the ordering proceeds via self-organization within one chain. Such a crossover between the two mechanisms is found for other solvents, although the crossover temperature depends on the solvent. It has been concluded that strong interactions between polymer and solvent molecules play important roles in controlling the gelation behavior of SPS/solvent systems.
Surface-Enhanced Infrared Spectroscopy: The Origin of the Absorption Enhancement and Band Selection Rule in the Infrared Spectra of Molecules Adsorbed on Fine Metal Particles
Authors: Osawa Masatoshi , Ataka Ken-Ichi , Yoshii Katsumasa , Nishikawa Yuji
Published: June 2005

Infrared transmission spectra of molecules adsorbed on silver island films evaporated on CaF2 have been investigated. The spectra are remarkably simple compared with those of the molecules in the solid state (KBr pellets). Only the vibrational modes which give dipole changes perpendicular to the metal surface are infrared active. In addition, their intensities are about 200 times larger than those of the free molecule. These results can be fully accounted for if the electric field which excites the surface molecule is perpendicular to the local surface of the metal islands and is stronger than the incident electric field. The origin of the absorption enhancement and the surface selection rule is discussed theoretically by using a classical electromagnetic model.
Low-Temperature Solid-State Electronic Absorption Fourier Transform Spectroscopy
Authors: Tanner Peter , Krishnan Jason
Published: June 2005

The study of inorganic solid-state electronic and vibronic transitions at low temperatures, by a wide-range Fourier transform spectrometer, covering the range 150 to 47,500 cm−1, with a resolution between 0.5 and 2.0 cm−1, is described. The types of electronic transitions of molecular ions are given, and the link between calculation and experimental measurement is highlighted. Factors contributing to the linewidths in solid-state electronic absorption spectrometry are identified. The instrumental techniques for sample preparation and the recording of spectra at low temperature are described, together with parameters affecting the resolution, precision, and calibration of a Fourier transform instrument. Problems which may arise from sample heating, spectrum fringing, aliasing, and the operation of spectrum subtraction are discussed. Some applications of the Fourier transform spectrometer are presented.
Recent Developments in Two-Dimensional Infrared (2D IR) Correlation Spectroscopy
Authors: Noda I. , Dowrey A. E. , Marcott C.
Published: June 2005

Recent developments in two-dimensional infrared (2D IR) correlation spectroscopy are reviewed. Since the initial introduction of the basic concept seven years ago, the field of 2D IR spectroscopy has evolved considerably. The method for generating 2D IR spectra from perturbation-induced time-dependent fluctuations of IR intensities and the properties of such 2D spectra are summarized first. Applications of 2D IR spectroscopy are then surveyed, and improvements in the instrumentation are reviewed. Different types of external perturbation schemes capable of inducing dynamic fluctuations of IR spectra are listed. Finally, a new 2D correlation method for dynamic spectral data with arbitrary time-dependence is discussed.
Two-Dimensional Infrared Spectroscopy of Electric-Field-Induced Reorientation Dynamics of a Mixed Nematic Liquid Crystal
Authors: Sasaki H. , Ishibashi M. , Tanaka A. , Shibuya N. , Hasegawa R.
Published: June 2005

A two-dimensional infrared (2D IR) spectrometer has been modified by the following methods to solve several problems on the 2D IR spectroscopy of electric-field-induced reorientation dynamics of a mixed nematic liquid crystal: (1) The response of the liquid crystal (LC) to an electric field was stabilized by an amplitude-modulated ac electric field. (2) Formulation of an anti-reflection coating (ARC) has been proposed to suppress the interference caused by multiple reflections between IR liquid crystal cell windows. (3) The Fourier transform procedure has been modified to correct the phase of the dynamic difference interferograms without spectral anomalies. These modifications can provide a better signal-to-noise ratio and reproducible 2D IR spectrum of a mixed nematic liquid crystal.
Instrumental Aspects of Dynamic Two-Dimensional Infrared Spectroscopy
Authors: Marcott Curtis , Dowrey A. E. , Noda Isao
Published: June 2005

Dynamic two-dimensional infrared (2D IR) correlation maps are a convenient means of examining the information contained in time-resolved IR spectra. Dynamic 2D IR spectra can be collected with the use of either dispersive or Fourier transform (FT) IR spectrometers. Use of a step-scanning FT-IR spectrometer has advantages over conventional rapid-scan FT-IR spectrometry when one is acquiring time-resolved IR data on time scales faster than about 0.1 s, because the spectral multiplexing is removed from the time domain. Dynamic IR spectra of atactic polystyrene (undergoing a small-amplitude oscillatory strain) collected on both dispersive and FT instrumentation are compared. Although the dispersive approach produces higher signal-to-noise ratios over small spectral regions, the multiplex advantage makes the FT approach attractive when broader spectral coverages are required. The first vibrational circular dichroism (VCD) spectrum [of (–)- α;-pinene] collected on a step-scanning interferometer is also presented.
Time-Resolved Pulsed FT-IR Emission Studies of Photochemical Reactions
Authors: Heard D. E. , Brownsword R. A. , Weston D. G. , Hancock G.
Published: June 2005

A time-resolved Fourier transform emission spectrometer, operating in the stop-scan mode, is demonstrated as an inexpensive and versatile instrument for observation of infrared vibrational chemiluminescence. The entire evolution of an emission spectrum is obtained from a single scan of the interferometer, with a spectral and temporal resolution of 2 cm−1 and 10 ns, respectively. Results are presented for a number of radical-radical reactions studied by this technique, where emission from highly excited CO, HF, CO2, and N2O is observed. Measurements include nascent vibrational distributions, quantum yields for branching into different product channels, and bimolecular rate constants for the production and vibrational relaxation of product species. Experiments at low total pressure enable nascent vibrational and rotational distributions to be found for the HF fragment of the CO2 laser photolysis of 1,1-chlorofluoroethylene. In addition, time-resolved spectra of HF, CO, CO2, CF4, and CHF3 are demonstrated for infrared emission observed from a reactive ion plasma etching chamber.
Step-Scan FT-IR Spectroscopy of Electron Transfer in the Photosynthetic Bacterial Reaction Center
Authors: Burie J.-R. , Leibl W. , Nabedryk E. , Breton J.
Published: June 2005

Step-scan light-induced FT-IR difference spectra (1800–1200 cm−1) of Rhodobacter sphaeroides photosynthetic bacterial reaction centers at low temperature and with a 10-μs time resolution are presented. The molecular changes and relaxation processes accompanying the photoxidation of the primary electron donor ( P) are already present 10 μs after excitation. The photoconversion of P to the triplet state gives rise to characteristic IR absorption changes which decay with a half-time of 130 μs. A negative band at 1695 cm−1 and a positive one at 1670 cm−1 are assigned to the 9-keto carbonyl of bacteriochlorophyll in the states P and 3 P, respectively.
Investigation of Time-Dependent Phenomena by Use of Step-Scan FT-IR
Authors: Palmer Richard A. , Chao James L. , Dittmar Rebecca M. , Gregoriou Vasilis G. , Plunkett Susan E.
Published: June 2005

The development, during the last decade, of modern step-scan interferometry instrumentation has allowed FT-IR to be applied to the study of time-dependent phenomena in ways not previously possible, because of the problems of uncoupling the spectral multiplexing from the temporal domain in the continuous-scan FT-IR mode. Specifically, the time regime from tens of nanoseconds to tens of milliseconds has been accessible to time-domain measurements to only a very limited degree with continuous-scan instrumentation and not at all for modulation-demodulation (frequency-domain) experiments in this time range. The step-scan technique not only works very well in this time regime and for slower phenomena, but is only prevented from application to faster processes by the signal strength, the speed of available detectors, the intensity of sources, and the speed and sophistication of the electronics. This paper surveys the various types of experiments which are either enhanced by use of step-scan FT-IR methods or are only possible by use of these techniques. The principles of step-scan instrumentation are reviewed, particularly those of retardation control, signal generation, and data acquisition, as well as the place of step-scan FT-IR relative to other techniques of dynamic vibrational spectroscopy. The importance of path difference (phase) modulation, particularly in frequency-domain measurements, the extraction and use of the signal phase, the creation of 2D FT-IR spectra, and the strategies for acquisition of both time- and frequency-domain data in the step-scan mode are discussed and illustrated.
High-Sensitivity Infrared Characterization of Ultra-Thin SiO2 Film on Si by Grazing Internal Reflection
Authors: Izumitani Junko , Okuyama Masanori , Hamakawa Yoshihiro
Published: June 2005

Infrared absorption in SiO2 ultra-thin film has been characterized by the grazing internal reflection (GIR) method, which is a high-sensitivity infrared spectroscopic technique for measuring weak absorption of ultra-thin dielectric film. It is confirmed from theoretical analysis that GIR is very sensitive to measurements of infrared absorption even in nanometer-order-thick SiO2 film sandwiched between a metal and semiconductor. The spectral configuration of the Si-O-Si stretching mode in the wavenumber range of 1000 to 1400 cm−1 changes drastically by changing the film thickness of 1–100 nm and the incident angle of 20–80°. The experimental spectra agree well with the calculated spectra. The spectral changes are attributed to the fact that optical confinement is subtly changed by the incident angle and the film thickness.
Transient 2D IR Correlation Spectroscopy of the Photopolymerization of Acrylic and Epoxy Monomers
Authors: Nakano Tatsuhiko , Shimada Shigeru , Saitoh Rieko , Noda Isao
Published: June 2005

Transient two-dimensional infrared (2D IR) correlation spectroscopy coupled with real-time Fourier transform infrared (RT FT-IR) measurement was used to analyze the reaction processes of photopolymerization systems. Unlike the previously developed 2D IR methods based on sinusoidally varying IR signals, a newly developed 2D correlation formalism applicable to transient spectroscopic signals having an arbitrary waveform was used. By this method, features associated with spectral intensity changes and peak shifts arising from polymerization reactions were clearly observed.
Charge Integrating Amplifier in the Near-Infrared Region Using an InGaAs PIN Photodiode
Authors: Mizumoto I. , Mashiko S. , Suzuki N.
Published: June 2005

A low-noise detection system using an InGaAs PIN photodiode for near-infrared spectroscopic measurement has been developed. The InGaAs PIN photodiode is more suitable than a Ge PIN photodiode for detecting low-level light in terms of dark current and quantum efficiency. The detection system consists of an InGaAs PIN photodiode with a charge integrating amplifier (InGaAs-CIA) operated at 77 K. A minimum detectable power of 10−16 W was achieved at a wavelength of 1.28 μm.
Step-Scanning Interferometer with Digital Signal Processing
Authors: Manning Christopher J. , Griffiths Peter R.
Published: June 2005

A novel step-scan FT-IR spectrometer incorporating a digital signal processor for demodulation of the detector signal is described. The potential advantages of this method of signal processing are discussed and illustrated. The instrument is based on a commercial cube-corner interferometer which has been modified by replacement of the drive motor with a stepper motor-micrometer and piezoelectric transducer combination. The interferometer retardation is feedback controlled by a 486–50 personal computer, which also controls the digital signal processor and collects spectral data. More than one phase modulation frequency can be imposed simultaneously, allowing for a multiplex advantage in photoacoustic depth profiling. Digital signal processing allows for simultaneous demodulation of multiple frequencies which would normally require several lock-in amplifiers. Data that illustrate the feasibility of these concepts are presented. The suitability of this instrument for double-modulation step-scan FT-IR measurements such as polymer stretching and electrochemically modulated step-scan FT-IR is also discussed.
Application of a Two-Dimensional Hadamard Encoding Mask for the Imaging of Thin-Layer Chromatography Plates by Laser-Induced Fluorescence or Surface-Enhanced Raman Scattering and for Use with a Photoacoustic Detector to Generate Three-Dimensional Photoacoustic Images
Authors: Fateley W. G. , Hammaker R. M. , Paukstelis J. V. , Wright S. L. , Orr E. A. , Mortensen A. N. , Latas K. J.
Published: June 2005

Spatial imaging of thin-layer chromatography plates using laser-induced fluorescence and surface-enhanced Raman scattering has been accomplished with a stationary two-dimensional Hadamard encoding mask. Detection of three nanograms of pararosaniline hydrochloride on a thin-layer chromatography plate was made possible by means of the surface-enhanced Raman phenomenon. The imaging capabilities of the stationary two-dimensional Hadamard encoding mask coupled with the depth profiling ability of photoacoustic detection allows for the three-dimensional photoacoustic imaging of a multiple analyte sample.
FT-IR Remote Sensing of Industrial Atmospheres for Spatial Characterization
Authors: Hammaker R. M. , Fateley W. G. , Chaffin C. T. , Marshall T. L. , Tucker M. D. , Makepeace V. D. , Poholarz J. M.
Published: June 2005

Two identical Fourier transform infrared (FT-IR) field monitoring systems have been used to investigate differences in apparent plume concentrations as a function of height. The two systems also have been used to monitor the same plume simultaneously at the same height to estimate the precision that can be expected. The data collected suggest that IR beam height may play a significant role in the measured concentrations of plume constituents.
One- and Two-Dimensional Infrared Time-Resolved Spectroscopy Using a Step-Scan FT-IR Spectrometer: Application to the Study of Liquid Crystal Reorientation Dynamics
Authors: Nakano Tatsuhiko , Yokoyama Toru , Toriumi Hirokazu
Published: June 2005

This paper describes the advances in step-scan FT-IR time-resolved spectroscopy (TRS) and its application to the study of liquid crystal reorientation dynamics. The most important advantage of step-scan interferometry lies in the fact that the optical retardation of the interferometer is held constant during the sampling of interferogram elements, and consequently the spectral multiplexing is decoupled from the time dependence of data collection. This feature of step-scan interferometry allows us to perform both time-domain (one-dimensional time-resolved spectroscopy: 1D TRS) and frequency-domain (two-dimensional frequency correlation spectroscopy: 2D IR) dynamic experiments without the need to deconvolute the time dependence of the sample response from that of the data collection process. The design of the step-scan FT-IR spectrometer used in this study (Bio-Rad FTS60A/896), the experimental setup for 1D and 2D TRS measurements, and the results of a performance test are detailed. The FT-IR TRS techniques applied to the dynamic analysis of liquid crystals have revealed new information that enables us to penetrate into detailed sub-molecular mechanisms of the electrically induced liquid crystal reorientation. The results include the following: (1) 1D FT-IR TRS with microsecond time resolution has been able to follow the real-time transition dynamics of each individual functional group in the molecule; (2) 2D FT-IR TRS, capable of analyzing spatial and temporal correlations between reorientational motions of different sub-molecular segments, has shown that a flexible chain appended to a rigid core of the liquid crystalline molecule undergoes a fast local motion in addition to the rotational relaxation motion of the entire molecule; and (3) 2D frequency correlation analyses have been able to isolate a hidden absorption band and have suggested a possible assignment of this new band. It is emphasized that all these results have been obtained by taking the advantage of time-resolved spectroscopy that provides both temporal and spectral information simultaneously. The results presented in this paper should illustrate the potential applicability of FT-IR TRS to the study of a wide variety of time-dependent phenomena.
Characterization of Interstitial Oxygen Striations in Silicon Single Crystals by the Micro-FT-IR Method
Authors: Uno Eiichi , Fusegawa Izumi , Yamagishi Hirotoshi
Published: June 2005

We will demonstrate that our micro-FT-IR mapping system is highly effective for investigating the behavior of interstitial oxygen (Oi) in Czochralski-grown silicon single crystals. The micro-FT-IR system experiences high space resolution, and Oi striations of as-grown silicon single crystals or of oxygen micro-precipitation after a thermal treatment are quantitatively measured. Oi micro-distribution profiles of as-grown crystals exhibit regular or irregular intervals and height, depending upon their crystal growth conditions. Oxygen micro-precipitations along growth striations are dependent upon their initial Oi micro-distribution profiles, and anomalous oxygen micro-precipitation is not observed.
Phase-Modulation Infrared Spectroscopy and its Application to Measurements of Photo-Induced Absorptions from Trans-Polyacetylene
Authors: Furukawa Yukio
Published: June 2005

The outline of phase-modulation infrared spectroscopy is described. The relationship between the frequency-domain response from phase-modulation experiments and the time-domain response from time-resolved experiments is derived. The microsecond dynamics following photoexcitation in treans-polyacetylene has been studied by phase-modulation infrared spectroscopy. The magnitude and phase (or in-phase and quadrature components) of the photo-induced infrared band at 1367 cm−1 have been measured at 78 K with modulation frequencies between 600 Hz and 10.5 kHz by using an experimental setup based on a continuousscan Fourier transform infrared spectrophotometer. The magnitude of this band shows an approximate ω−0.5 dependence for frequencies below 9 kHz and a rapid decrease above 9 kHz. These results are inconsistent with a unimolecular decay, which should show a dependence of the form ω−1
Direct Kinetic Measurements of Vinyl Polymerization on Metal and Silicon Surfaces Using Real-Time FT-IR Spectroscopy
Authors: Yang D. Billy
Published: June 2005

A real-time FT-IR (RT/FT-IR) technique has been used to perform direct kinetic measurements of vinyl polymerization on metal and silicon surfaces. Here, we are reporting our results in studies of anaerobic and photo-induced anionic polymerizations of monomers containing vinyl functional groups (>C=C<) for adhesive and coating applications. For anaerobic polymerization we are investigating the hydroperoxide-initiated free radical polymerization of model multifunctional methacrylate monomer systems. We will report the results of our studies on the catalytic effects of different dithiolate complexes and related accelerators. In photo-induced anionic polymerization we will report our studies for ethyl cyanoacrylate (CA) polymerization initiated by a controlled release of anion from a stable chromium complex precursor ( trans-Cr-(NH3)2(NCS)4−K+). Because of high surface sensitivity of the CA monomer, the polymerization kinetic studies were performed on a clean silicon surface at room temperature. The effect of the initiator concentration and irradiation wavelengths on polymerization kinetic rate will be discussed. The acrylic polymerization was monitored with the use of the C=C stretching band at 1634 and 1627 cm−1 for polyglycol dimethacrylate and cyanoacrylate, respectively. Both the degree of polymerization and the intrinsic rates of the polymerization reactions were calculated for kinetic comparisons. For anaerobic polymerization studies, GC/FT-IR software was used which provided a real-time screen display of IR spectral changes as the reaction proceeded. For very fast cyanoacrylate anionic polymerization studies, new FT-IR kinetic software was used to collect 204 spectra per minute with one spectrum per scan. In this case, the interferograms were collected first; post-Fourier transform conversion and spectral script reduction were then performed. Some detailed experimental techniques and polymerization reaction mechanisms will also be discussed.
Studies on the Instrumental Factors Determining Errors in the Measurements of Raman Band Profiles. Part II: Effect of the Signal Noise on Vibrational Relaxation Functions and Relaxation Times
Authors: Giorgini M. G. , Mariani L. , Morresi A. , Paliani G. , Cataliotti R. S.
Published: June 2005

A method for the determination of the effect of the signal noise on vibrational correlation functions and relaxation times obtained in stationary spectroscopic measurements is proposed. It rests upon the assumption that electronic noise is mainly due to the photon counting which, for fast electronics, is described by Poisson statistics. The application of this method leads to results expressed as standard deviations which, for correlation functions, appear in very close agreement with the conclusions of statistical analysis, while for the relaxation times the results are lower than those delivered by statistical analysis.
What is Wrong with MEM?
Authors: Kauppinen Jyrki K. , Saario Eija K.
Published: June 2005

The maximum-entropy method (MEM) is a typical method, where the power spectral estimator is claimed to be proportional to the power of the transfer function of the autoregression (AR) model filter. The AR power spectral estimator is shown theoretically and with practical examples to be a very bad approximation of the true power spectrum. The estimator loses almost all the intensity (line strength) information of the power spectrum, and there can be very large distortions in the estimated power spectrum. The reason for the malfunction of the MEM is the approximation where the autocorrelation function of any random white noise is assumed to be the Dirac delta function. However, this is not true in practice.
Simultaneous Acquisition of Spectral and Spatial Intensity Distribution
Authors: Okamoto Takayuki , Takahashi Akinori , Yamaguchi Ichirou
Published: June 2005

A method for recording and reconstructing spectral and spatial intensity distributions of sources is described. Three-dimensional information (two for spatial and one for wavelength) of the sources is simultaneously recorded as their projected forms by an imaging system including a crossed phase grating. A modified multiplicative algebraic technique is developed to reconstruct the original distribution. In experiments we obtained nine projection patterns with equal brightness of a color slide illuminated by a tungsten lamp. The reconstructed distribution shows good agreement with that measured by interference filters.
Autostandard Method: Quantitative IR Multicomponent Analysis for Films with Indeterminate Pathlength
Authors: Jamróz Michał H. , Dobrowolski Jan Cz.
Published: June 2005

The autostandard method is a new analytical method based on the relationship between intensities of certain bands and a number of specific oscillators in molecules. This method, complementary to the known ratio method, is used for a quick determination of the component contents of a chemical system under difficult experimental situations, when the layer thickness cannot be determined (e.g., polymer films and other solids of irregular surfaces, very viscous liquid films, mulls in nujol).
Quantitative Analysis of Peptides by Matrix-Assisted Laser Desorption/Ionization Time-Of-Flight Mass Spectrometry
Authors: Gusev Arkady Ia. , Wilkinson William R. , Proctor Andrew , Hercules David M.
Published: June 2005

Quantitative analysis of peptides using internal standards was carried out with the use of matrix-assisted laser desorption/ionization (MALDI) on a time-of-flight mass spectrometer in a ferulic acid matrix. Spectra were collected and averaged over several areas of the sample surface at constant laser energy, and a defocused beam was used to improve reproducibility. A calibration curve was plotted, showing a correlation coefficient of 0.992 and a relative standard deviation of 1.83%. The accuracy and precision of this technique were sensitive to the crystal structure of the matrix and saturation effects of the instrument's detector.
Quantitative Analysis of Water in Milk by FT-IR Spectrometry
Authors: Hop E. , Luinge H.-J. , Van Hemert H.
Published: June 2005

FT-IR spectrometry was used to determine the water content of milk. Transmission spectra were taken with a 40-μm capillary cell. Calibration was performed in the mid-infrared on a specific water band at 2110 cm−1 and a reference region at 2590 cm−1. Multiple linear regression resulted in a prediction error of 0.14% water for milk samples having a water content between 84.9 and 88.0 w/w %.
JCAMP-DX for NMR
Authors: Davies Antony N. , Lampen Peter
Published: June 2005

Following the development and publication of the JCAMP-DX protocol 4.24 and its successful implementation in the field of infrared spectroscopy, data exchange without loss of information, between systems of different origin and internal format, has become a reality. The benefits of this system-independent data transfer standard have been recognized by workers in other areas who have expressed a wish for an equivalent, compatible standard in their own fields. This publication details a protocol for the exchange of Nuclear Magnetic Resonance (NMR) spectral data without any loss of information and in a format that is compatible with all storage media and computer systems. The protocol detailed below is designed for spectral data transfer, and its use for NMR imaging data transfer has not as yet been investigated.
Factors Influencing Characteristic Mass in the Graphite Furnace
Authors: Zheng Yansheng , Su Xingguang , Quan Zhe
Published: June 2005

Measurements of characteristic masses for Ag, Cd, Cr, Ga, Ge, and In have been made over a broad temperature range. The experimental results show that the experimental values of m0 have appeared to be stable to better than 10–15% when the analytes are atomized in the temperature ranges studied. Influences of atomization temperatures on the ratio m0(calc)/ m0(exp) were studied when the analytes were evaporated from the wall, with the use of the platform and the V-shaped boat techniques. For Ag and Cd the ratio m0(calc)/ m0(exp) does not change significantly, and their values appeared to be nearly 100% in the temperature ranges studied when the analytes were evaporated with the use of the platform and the V-shaped boat techniques. However, for the remaining four elements (Cr, Ga, Ge, and In) the ratio m0(calc)/ m0(exp) increases with the rise of atomization temperatures, and their values appear to be only about 20–50% in the absence of a matrix modifier. However, the ratio m0(calc)/ m0(exp) is obviously increased in the presence of a matrix modifier.
Spectrofluorometric Probe Method for Examining Preferential Solvation in Binary Solvent Mixtures
Authors: Acree William E. , Wilkins Denise C. , Tucker Sheryl A.
Published: June 2005

A spectrofluorometric method is developed to examine preferential solvation of a probe molecule dissolved in binary solvent mixtures. The method assumes that the solvational sphere around every fluorophore is solvated by only one type of solvent component and that each solvated fluorophore contributes to the measured emission intensity. Expressions derived from the model are illustrated with the use of observed fluorescence emission behavior of 3,4-dihydrobenzo[ghilperylene dissolved in binary n-heptane + 1,4-dioxane and dibutyl ether + acetonitrile solvent mixtures, which were measured as part of the present study.
Wavelength- and Time-Resolved Investigation of Laser-Induced Plasmas as a Continuum Source
Authors: Xu Ning , Majidi Vahid
Published: June 2005

Time- and wavelength-resolved laser-induced plasma emission spectra in helium, argon, nitrogen, air, and helium/argon mixture were obtained from 200 to 700 nm. Stability studies showed that plasmas formed in helium had about 5% relative standard deviation in emission at most wavelength regions. A radiant intensity of 8 × 1011 photons/pulse sr was produced at 633 nm with a moderate laser power. Plasma temporal development was investigated in various gases. In general, the continuum emission was observed only during the first few microseconds following the laser onset. Plasmas in argon have the longest decay time, followed by helium and nitrogen. The feasibility of using the laser-induced plasma as a continuum source for the study of transient molecular absorption was demonstrated.
Quantitative Analysis of Glucose Syrups by ATR/FT-IR Spectroscopy
Authors: Mirouze F. De Lène , Boulou J. C. , Dupuy N. , Meurens M. , Huvenne J. P. , Legrand P.
Published: June 2005

Thanks to what has been achieved by the Fourier transform, infrared spectrometry can now become a state-of-the-art device in quality control laboratories if we consider its precision and the gain in time it ensures in comparison to results from traditional analytical methods such as chromatography. Moreover, the increasing number of new mathematical regression methods such as Partial Least-Squares (PLS) regression allows multicomponent quantitative analysis in mixtures. For instance, the analysis of the three main components (glucose, maltose, and fructose) of the dry substance which represents about 70% (w/v) in glucose syrups can be done with the use of Attenuated Total Reflectance (ATR) spectroscopy with a precision in the region of 3 to 5%, whereas the time required to obtain an analysis report is about five minutes. The high similarity between the glucose and the maltose may make the analysis difficult.
Analytical Potential of Surface-Enhanced Fourier Transform Raman Spectroscopy on Silver Colloids
Authors: Wentrup-Byrne E. , Sarinas S. , Fredericks P. M.
Published: June 2005

Although FT-Raman is becoming an increasingly popular analytical tool, it has proved to be relatively insensitive for the analysis of solutions. This is a serious problem, particularly for studies in the biochemical area. Because resonance Raman is not available for near-infrared excitation, surface-enhanced Raman spectroscopy (SERS) provides an important pathway to improved sensitivity. This study is concerned with assessing the potential of SERS with FT-Raman as an analytical tool for aqueous solutions. The SERS effect was investigated for a variety of organic molecules, both nitrogen and non-nitrogen containing, with silver colloids prepared by different literature methods. Various factors were studied: the effect of colloid preparative method, age of the colloid, addition of potassium chloride, time after addition of analyte, and concentration of analyte. In some cases, an analyte gave no SERS effect with a particular colloid, but exhibited a large SERS effect with a colloid prepared by a different method.
Study of Different Photon Statistics Techniques, Based on Time-Interval Measurement, Applied to Fluorescence Decay Spectroscopy
Authors: Calleja F.-J. , Jarabo S. , Rebolledo M. A.
Published: June 2005

In this paper we present a study of different existing techniques which are used in fluorescence decay spectroscopy and are based on time-interval measurement. An improvement in some of these techniques is obtained by deducing more general expressions applicable to them. By using computer simulation methods the accuracies of these techniques are studied and compared.
Infrared Intensities of Liquids XI: Infrared Refractive Indices from 8000 to 2 cm−1, Absolute Integrated Intensities, and Dipole Moment Derivatives of Methanol at 25°C
Authors: Bertie John E. , Zhang Shuliang L. , Eysel Hans H. , Baluja Shipra , Ahmed M. Khalique
Published: June 2005

This paper reports infrared absorption intensities of liquid methanol at 25°C between 8000 and 2 cm−1. Measurements were made by attenuated total reflection spectroscopy by four different workers between 1984 and 1991, with the use of CIRCLE cells of two different lengths and with several different alignments of the cell in the instrument. Steps were taken to ensure that as few parameters as possible remained unchanged throughout the series of measurements, to try to reveal systematic errors. The reproducibility was better than ±2.5% in regions of significant absorption. In order to allow comparison between different methods, results of all methods were converted to real and imaginary refractive index spectra. Measurements were also made by transmission spectroscopy in regions of weak absorption, with results that agreed excellently with those from ATR. The ATR and transmission results were combined to give a spectrum between 7500 and 350 cm−1. This spectrum agreed excellently with literature results from 350 to 2 cm−1, and the two sets of measurements were combined to yield a spectrum from 7500 to 2 cm−1. The imaginary refractive index was arbitrarily set to zero between 7500 and 8000 cm−1, where it is always less than 2 × 10−6, in order that the real refractive index can be calculated below 8000 cm−1 by Kramers-Kronig transform. The results are reported as graphs and as tables of the real and imaginary refractive indices between 8000 and 2 cm−1, from which all other infrared properties of liquid methanol can be calculated. The accuracy is estimated to be ±3% below 5000 cm−1 and ±10% above 5000 cm−1 for the imaginary refractive index and better than ±0.5% for the real refractive index. To obtain molecular information from the measurements, one calculates the imaginary molar polarizability spectrum, [Formula: see text] vs. [Formula: see text], under the Lorentz local field assumption, and the area under [Formula: see text] bands is separated into contributions from different vibrations under several approximations. Much accuracy is lost in this process. The changes of the dipole moment during normal vibrations, and during OH, CH, and CO bond stretching and COH torsional motion, are presented.
Molecular Structure of Nitrogen in Coal from XANES Spectroscopy
Authors: Mullins Oliver C. , Mitra-Kirtley Sudipa , Van Elp Jan , Cramer Stephen P.
Published: June 2005

Five major nitrogen chemical structures, present in coals of varying ranks, have been quantitatively determined with the use of nitrogen x-ray absorption near-edge spectroscopy (XANES). Similar studies of the sulfur chemical structures of coals have been performed for the last ten years; nitrogen studies on these fossil-fuel samples have only recently been realized. XANES spectra of coals exhibit several distinguishable resonances which can be correlated with characteristic resonances of particular nitrogen chemical structures, thereby facilitating analysis of these complicated systems. Many model compounds have been examined; for some, the relative peak positions are explained in terms of the orbital description of the lone pair of electrons. All features in the XANES spectra of coals have been accounted for; thus, all the major structural groups of nitrogen present in coals have been determined. A wide variety of aromatic nitrogen compounds is found in the coals; no evidence of saturated amine is found. Pyrroles, pyridines, pyridones, and aromatic amines are found in coal; of these, pyrrolic structures are the most prevalent. Pyridine nitrogen is prevalent in all except low-rank coals. The low pyridine content in low-rank (high-oxygen) coals correlates with a large pyridone content. This observation suggests that, with increasing maturation of coal, the pyridone loses its oxygen and is transformed into pyridine. Aromatic amines are present at low levels in coals of all rank. The spectral effects of aromatic amines are shown by comparing the XANES spectra of coal and petroleum asphaltenes.
Studies on the Instrumental Factors Determining Errors in the Measurements of Raman Band Profiles. Part I: Optical Factors—A Comparison of Three Different Methods
Authors: Mariani L. , Morresi A. , Giorgini M. G. , Paliani G. , Cataliotti R. S.
Published: June 2005

A treatment is proposed which takes into account the following error sources in Raman band shape measurements: incident beam polarization, polarization analyzer misorientation, monochromator response, and observation over a finite solid angle. Three methods generally adopted for this type of measurements are compared in terms of the amount of spurious anisotropic component which enters the isotropic profile. The pertinence zones of each method are shown. The percentage of error is expressed by well-defined quantities entering analytical equations; this allows the experimentalist to choose the more suitable method on the basis of the experimental setup.
FT-Raman On-Line Analysis of PCI3 Reactor Material
Authors: Freeman John J. , Fisher David O. , Gervasio Gregory J.
Published: June 2005

Fourier transform (FT)-Raman spectroscopy has been applied to the online analysis and control of a PCI, reactor. This particular analytical technique was selected from a consideration of the Raman scattering efficiencies of the constituents of the reaction and the ability of the fiberoptic-coupled, near-IR, FT-Raman systems to remotely sample the toxic and potentially hazardous reaction mixture. In this communication we describe the Raman spectra of P4, PCl3, PCl5, and P4 dissolved in PCl3, as well as related compounds, along with relative band intensities of the constituents of the reaction. Factors leading to the optimum FT-Raman configuration for this particular process control problem are discussed in detail.
Spinning-Cell FT-Raman Spectroscopy: Application to Crystalline Octacarbonyldicobalt(0), Co2(CO)8
Authors: Brienne Stéphane H. R. , Markwell Ross D. , Barnett Steven M. , Butler Ian S. , Finch James A.
Published: June 2005

Raman spectrum of crystalline octacarbonyldicobalt(0), Co2(CO)8, has been successfully obtained for the first time by using a Fourier transform instrument together with a spinning sample cell to avoid decomposition of Co2(CO)8 upon exposure to the near-IR laser radiation used to excite the spectrum. Previously, only limited regions of the Raman spectrum could be obtained with visible laser excitation because of extensive sample burning. The new FT-Raman results, combined with the related IR data from the literature, provide a better description of the vibrational properties of this important binary metal carbonyl complex.
Laser-Based Double-Beam Thermal Lens Detector for Microcolumn Liquid Chromatography
Authors: Rosenzweig Zeev , Yeung Edward S.
Published: June 2005

A double-beam laser absorption detection system for high-performance liquid chromatography (HPLC) using the thermal lens effect has been developed. An electronic circuit is used to reduce the background noise level. The circuit is based on direct subtraction of reference and signal photocurrents under feedback control. A practical intensity signal-to-noise (S/N) ratio of 5 × 10−6 for normal absorption and 1 × 10−5 for thermal lens absorption measurements is achieved. The thermal-lens enhancement per unit laser power is 0.62 mW−1. For a 34-mW beam power at the sample cell, the absorption signal is 22 times higher in comparison to normal absorption. The system is shown to have a noise level of 2 × 10−7 AU. Amounts as low as 1 × 10−10 M 2′-Cl-4-dimethylaminoazobenzene at the flow cell or 1.5 fmol injected can be detected (S/N = 3). This corresponds to a 10-fold improvement in comparison to normal absorption measurements with the same electronic canceller and a 100-fold improvement in comparison to those for commercial absorption detectors.