Showing papers on "Fourier transform spectroscopy published in 1998"
347 citations
01 Jan 1998
TL;DR: In this article, the authors proposed a waveguide configuration optical spectroscopy method for sub-millimeter wave spectra, which is based on the wave-guide configuration of the Volkov waveguide.
Abstract: Teraheeertz time-domain spectroscopy, M. Nuss and J. Orenstein coherent source submillimeter wave spectroscopy, G. Kozlov and A. Volkov waveguide configuration optical spectroscopy, G. Gruner far-infrared Fourier transform spectroscopy, L. Genzel magneto-optical millimeter wave spectroscopy, K. Dahl, P. Goiy and J.P. Kotthaus.
341 citations
Book•
01 Jan 1998
TL;DR: In this paper, the dielectric response functions are used for spectroscopy in the Visible and Near-Visible Spectral Range (VRS) in the presence of electromagnetic radiation.
Abstract: Electromagnetic Radiation- Light Sources with General Application- Spectral Analysis of Light- Detection of Electromagnetic Radiation- The Dielectric Response Functions- Spectroscopy in the Visible and Near-Visible Spectral Range- Symmetry and Selection Rules- Light Scattering Spectroscopy- Infrared Spectroscopy- Magnetic Resonance Spectroscopy- Ultraviolet and X-Ray Spectroscopy- Spectroscopy with #x03B3 Rays- Generalized Form of Response Functions- Spectroscopy with Electrons, Positrons and Muons- Spectroscopy of Mesoscopic and Nanoscopic Solids- Neutron Scattering- Spectroscopy with Atoms and Ions- Appendix a,b,cdef
251 citations
TL;DR: In this paper, the apparent and cascade cross-sections were measured with a monochromator-PMT system and a weak emission FTS system, respectively, for the incident electron energy range between onset and 300 eV.
Abstract: To experimentally determine electron-impact excitation cross sections with the optical method, it is necessary to measure all transitions out of a level (the apparent cross sections), as well as the cascades into the level. In the case of the ten ${3p}^{5}4p$ levels of argon, the emissions to lower levels lie in the visible and near infrared (660\char21{}1150 nm) and are hence observable with a monochromator\char21{}photomultiplier-tube (PMT) system. A Fourier-transform spectrometer (FTS) allows us to measure the previously uninvestigated cascades that lie in the infrared. For the incident electron energy range between onset and 300 eV, we have measured the apparent cross sections with a monochromator-PMT system, and the cascade cross sections with a weak emission FTS system. The magnitude of both the apparent and cascade cross sections increases with target gas pressure due to radiation trapping effects. By subtracting the cascade contributions from the apparent cross sections, we have determined the direct cross sections and verified that they do not vary with pressure in the 0.5\char21{}4-mTorr pressure range considered here.
172 citations
TL;DR: An attenuated total reflectance Fourier transform infrared method has been developed that allows collection of spectra from proteins in solution that eliminates any structural perturbations induced by the internal reflection element (IRE), and thus the spectra reflect the solution conformation of the protein.
142 citations
TL;DR: In this article, the authors investigated the speciation of As(V) bearing oxyanions (AsO43−) in cementitious environment by X-ray diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FT-IR).
137 citations
TL;DR: In this article, free carrier concentration profiles were determined by Fourier Transform Infrared (FTIR) variable angle spectroscopic ellipsometry, which exploits carrier absorption in the mid-infrared spectral range.
115 citations
TL;DR: In this article, a detailed study was carried out on a few α,α′-dimethyl end-capped oligothiophenes which have been in situ doped with dry iodine vapors, at different concentrations.
Abstract: We present the results of a detailed study carried out on a few α,α′-dimethyl end-capped oligothiophenes which have been in situ doped with dry iodine vapors, at different concentrations. The doping process of these well sized oligomers (from dimer to hexamer) has been monitored by using Fourier transform infrared absorption and Fourier transform raman scattering spectroscopies. These data, when combined with the vibrational full assignment of the oligomers in the neutral state and the electronic absorption bands recorded for both neutral and doped compounds, provide a complete spectroscopic characterization of a full series of positive polaron-type model defects of doped polythiophene. We have also performed density functional theory quantum-chemical calculations in order to analyze the effects of ionization on the geometries and vibrational spectra of these systems.
104 citations
01 Feb 1998
TL;DR: In this article, the results of an ongoing collaborative project between the New Jersey Institute of Technology (NJIT) and SEMATECH on the temperature-dependent emissivity of silicon-related materials and structures are presented.
Abstract: The results of an ongoing collaborative project between the New Jersey Institute of Technology (NJIT) and SEMATECH on the temperature-dependent emissivity of silicon-related materials and structures are presented in this study. These results have been acquired using a spectral emissometer. This emissometer consists of a Fourier Transform Infra-Red (FTIR) spectrometer designed specifically to facilitate simultaneous measurements of surface spectral emittance and temperature by using optical techniques over the near- and mid-IR spectral range and temperatures ranging from 300 K to 2000 K. This noncontact, real-time technique has been used to measure radiative properties as a function of temperature and wavelength for a wide range of silicon-related materials and structures. The first results of the temperature and wavelength dependent emissivity and hence refractive index of silicon nitride, in the literature, is presented in this study.
93 citations
TL;DR: It is shown that short coherence interferometry has the potential to measure the three-dimensional distribution of the spatial structure of a sample with a resolution determined by the coherence length of the light source, absorption spectrum and a dispersion.
Abstract: A Fourier transform spectrometer is used to simultaneously measure distance, dispersion and spectrum. It is shown that short coherence interferometry has the potential to measure the three-dimensional distribution of the spatial structure of a sample with a resolution determined by the coherence length of the light source, absorption spectrum with a resolution of 1 cm−1 and a dispersion with a resolution of up to 1025.
88 citations
TL;DR: In this paper, the absorption spectra of gas-phase molecular oxygen and zero air at temperatures of 223 and 283 K were measured using a coolable multipass-optics gas cell and Fourier transform spectroscopy in the wavelength range 455 to 830 nm (12,000-22,000 cm -1 ).
Abstract: Absorption spectra of gas-phase molecular oxygen and zero air at temperatures of 223 and 283 K have been measured in the laboratory using a coolable multipass-optics gas cell and Fourier transform spectroscopy in the wavelength range 455 to 830 nm (12,000-22,000 cm -1 ). Net absorption cross sections of the O 2 A-, B-, and γ-bands at <0.002 nm spectral resolution, and pressures of 100 and 1000 hPa zero air have been determined. Binary absorption cross sections of the collision-induced O 4 bands at <0.18 nm spectral resolution and a pressure of 1000 hPa pure oxygen have been determined, with corrections for the O 2 γ-band absorption. Calculated integrated absorption intensities and, for the O 2 A- and B-bands, effective Einstein A-coefficients are compared with previous literature values.
TL;DR: In this paper, two new sampling and analysis techniques for assessing the condition of EPDM (ethylene-propylene diene monomer) composite insulators are presented, which are named the oxidation index and the chalking index.
Abstract: Two new sampling and analysis techniques for assessing the condition of EPDM (ethylene-propylene diene monomer) composite insulators are presented. Polymer oxidation is assessed by removing small amounts of surface polymer by swabbing with xylene and analyzing this material by FTIR (Fourier transform infrared) emission spectroscopy. A measure of the amount of surface chalking is obtained by scraping a small amount of degraded surface material with a blade and analyzing by FTIR absorption spectroscopy. Numerical indices quantifying the amount of oxidation and surface chalking are obtained by calculating the ratios of absorption or emission peak heights in the infrared spectra. These indices are named the oxidation index and the chalking index. Three types of field-aged 275 kV EPDM composite insulators are investigated and the results from the new techniques compared with analyzes by XPS (X-ray photoelectron spectroscopy) with good agreement. It is found that for two types of insulator that the oxidation index is increased in regions near the HV conductor.
TL;DR: In this article, the vibrational analysis of the absorption spectrum of 12C2D2 between 5150 and 8000 cm−1, recorded by Fourier transform absorption spectroscopy, and between 12
Abstract: We have performed the rovibrational analysis of the absorption spectrum of 12C2D2 between 5150 and 8000 cm−1, recorded by Fourier transform absorption spectroscopy, and between 12 800 and 16 600 cm−1, recorded by intracavity laser absorption spectroscopy. Respectively 10 and 9 bands are reported for the first time in each range. Improved or new rovibrational parameters were obtained for 34 vibrational levels altogether. The vibrational energies we obtained, together with those reported in the literature, were taken into account to model the vibrational energy pattern in 12C2D2(X 1Σg+). The analysis was performed in successive steps, inferring each time suitable parameters. The 44/55, 11/33, 12/33, and 1/244 quartic order anharmonic resonances were introduced during the procedure. They altogether define vibrational clusters which are characterized by only two dynamical constants of motion, Ns=V1+V2+V3 and k=l4+l5.
TL;DR: In situ Fourier transform infrared (FTIR) absorption spectroscopy has been used to determine the fractional depletion of silane in a radiofrequency (rf) glow discharge as discussed by the authors.
Abstract: In situ Fourier transform infrared (FTIR) absorption spectroscopy has been used to determine the fractional depletion of silane in a radio-frequency (rf) glow discharge. The technique used a simple single-pass arrangement and was implemented in a large-area industrial reactor for deposition of amorphous silicon. Measurements were made on silane plasmas for a range of excitation frequencies. It was observed that, at constant plasma power, the fractional depletion increased from 35% at 13.56 MHz to 70% at 70 MHz. With a simple model based on the density continuity equations in the gas phase, it was shown that this increase is due to a higher dissociation rate and is largely responsible for the observed increase in the deposition rate with the frequency.
TL;DR: It is shown that real-time visualization of surface profiles is possible and measurements with a repeatability of approximately 5 nm rms are reported, which is good agreement with stylus profiler measurements.
Abstract: We present a fast white-light interference method for measuring surface depth profiles at nanometer scales. Previously reported white-light profilers have relied either on path difference scanning or on spectral analysis of the reflection from a fixed interferometer. We show that by performing this spectral analysis with an imaging Fourier transform spectrometer, the high speed of spectral techniques may be combined with the simple data interpretation characteristic of the scanning method. Giving experimental results from a profiler based on this principle, we show that real-time visualization of surface profiles is possible and we report measurements with a repeatability of approximately 5 nm rms. We also demonstrate good agreement with stylus profiler measurements.
TL;DR: In this article, the molecular constants of NO 3 in the ground electronic 2 A 2 ) state have been determined by using observed combination differences derived from the infrared spectrum between 1300 and 8000 cm −1, as follows, B = 0.458 5485(63), D N =0.1113(12), D NK =−0.2121(27)×10 −5, ϵ bb =− 0.016 49(13) cm − 1, with one standard deviation in parentheses.
TL;DR: In this article, a plasma spray coated hydroxyapatite was studied using diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy, and the effect of spray distance on the coating and the difference between the surface and the bulk of the coating was investigated.
TL;DR: In this paper, the properties of microporous layered tin sulfides have been investigated and the combined spectroscopic results provide a rather comprehensive picture of structure-property relations for this novel class of solids, which have the unusual ability of being able to behave as both molecular sieve and intercalation materials to a range of guests.
Abstract: 119 Sn solid state nuclear magnetic resonance, 119Sn Mossbauer, Fourier transform Raman and variable temperature single crystal UV–VIS absorption, emission and excitation spectra of some archetypal microporous layered tin sulfides, denoted (Et4N)2Sn3S7 (TEA-SnS-1), (C6H12N2H)2Sn3S7 (DABCOH-SnS-1), (NH4)0.5(Et4N)1 .5Sn3S7 (ATEA-SnS-1) and (Pr4N)2Sn4S9 (TPA-SnS-3), are reported. The combined spectroscopic results provide a rather comprehensive picture of structure–property relations for this novel class of solids, which have the unusual ability of being able to behave as both molecular sieve and intercalation materials to a range of guests.
TL;DR: In this paper, the effect of semiconducting transition metal oxide nanoparticles on the luminescence properties of conjugated polymers was investigated and the synthesis of a poly(p-phenylenevinylene) (PPV) system was reported.
Abstract: It is well established that the dispersion of nanosized metal particles in a polymer matrix can induce nonlinear optical properties, yet very little is known about the effect of semiconducting transition metal oxide nanoparticles on luminescence properties of conjugated polymers. In this paper, we report the synthesis of a nanostructured /poly(p-phenylenevinylene) (PPV) system and show by diffuse reflectance infrared Fourier transform spectrometry that a stable conjugated nanocomposite is obtained. Investigation of the photoluminescence (PL) properties reveals both a broadening and a blueshift of the emission spectra. Adsorption of oxygen is found to be stronger on the nanocomposite than on PPV and to reversibly quench the PL emission, thus suggesting enhanced gas sensing properties. A tentative mechanism explaining the role of n- is briefly discussed.
TL;DR: In this paper, the synthesis and structural characterization of AV-1 (Aveiro microporous solid no. 1), the first synthetic yttrium silicate containing stoichiometric amounts of framework sodium cations, are reported.
Abstract: The synthesis and structural characterization of AV-1 (Aveiro microporous solid no. 1), the first synthetic microporous yttrium silicate containing stoichiometric amounts of framework sodium (and yttrium) cations, are reported. AV-1, Na4K2Y2Si16O38·10H2O, possesses the structure of the rare mineral montregianite. The synthesis and structural characterization of AV-2, an alkali calcium silicate hydrate (ideal composition HKCa2Si8O19·6H2O) analogue of the rare mineral rhodesite, are also reported. The structures of AV-1 and AV-2 are characterized by the same type of double silicate layers, but important differences exist with respect to the constitution of the octahedral layers and channel species. AV materials have been characterized by a range of techniques, viz., scanning electron microscopy (SEM), powder X-ray diffraction (XRD), 29Si and 23Na single- and triple-quantum (3Q) magic-angle spinning (MAS) NMR spectroscopy, Fourier transform spectroscopy (FTIR), and thermogravimetric analysis (TGA).
TL;DR: In this article, the polarization modulation infrared linear dichroism (IRLD) was used to study the time dependence of the orientation function of polystyrene PS and poly vinyl methyl ether PVME blends.
TL;DR: In this article, the authors used high-resolution Fourier transform spectroscopy to determine the laboratory wavelengths of MgI-2853A, MgII-2796A and Mg-II-2803A.
Abstract: Strong ultraviolet resonance transitions are observed routinely both in the Galactic interstellar medium and in quasar absorption systems. The quality of the astronomical spectroscopic data now available demands more precise laboratory rest wavelengths. Of particular interest is the accuracy with which one can constrain space–time variations in fundamental constants using quasar spectra. A recent analysis by Webb et al. of 25 quasar spectra using Mg and Fe transitions tentatively suggests that the fine-structure constant was smaller at earlier epochs. To permit a check on this result, and to allow further more extensive investigations, we have carried out a new determination of the laboratory wavelengths of Mg i 2853 A, Mg II 2796 A and Mg II 2803 A by high-resolution Fourier transform spectroscopy. Our results for Mg II 2796 A are consistent with the value measured independently by two other groups. To our knowledge, no previous measurements of comparable precision exist for Mg I 2853 A and Mg II 2803 A.
TL;DR: In this paper, the authors measured the FT spectrum of natural OCS from 4800 to 8000 cm(-1) with a near Doppler resolution and a line position accuracy between 2 and 8 x 10(-4) cm(1).
TL;DR: It is concluded that the 1480 cm-1 band arises from QB- of PSII and tentatively assign it to the upsilon(CO) mode of the semiquinone anion QB-.
Abstract: Time-resolved FTIR spectroscopy has been used to kinetically characterize the vibrational properties of intact photosystem II-enriched membrane samples undergoing the S1QB-to-S2QB- transition at ro...
TL;DR: In this paper, a method was developed to calculate quantitatively the infrared spectrum of a gas as measured by Fourier transform infrared (FTIR) spectroscopy, using spectroscopic parameters found in the HITRAN database by mimicking the mathematical processes occurring in the FTIR.
Abstract: A method has been developed to calculate quantitatively the infrared spectrum of a gas as measured by Fourier transform infrared (FTIR) spectroscopy. Using spectroscopic parameters found in the HITRAN database, a high resolution spectrum ( 1 cm -1 ) by mimicking the mathematical processes occurring in the FTIR. The smoothing consists of applying an inverse Fourier transform to generate an interferogram, truncating and apodizing the interferogram, and then Fourier transforming back to yield the finished spectrum. Comparisons to experimental measurements of CH 4 in air and H 2 at various concentrations, pressures, and resolutions have confirmed the accuracy of the method. The major advantages of this technique are that an entire gas band is calculated (not just peak values), the method works on overlapping and closely spaced peaks, and quantitative calculation of spectra at any temperature and pressure is possible. These features are particularly useful for making quantitative FTIR measurements in chemical vapor deposition reactors where there are substantial variations in temperature and partial pressure.
TL;DR: In this paper, the bonding properties of hydrogenated amorphous germanium-carbon (a-Ge1−xCx:H) alloy films, deposited by the rf-co-sputtering technique, were measured by Fourier transform infrared, micro-Raman and X-ray photoelectron spectroscopies.
Abstract: The bonding properties of hydrogenated amorphous germanium–carbon (a-Ge1−xCx:H) alloy films, deposited by the rf-co-sputtering technique, were measured by Fourier transform infrared, micro-Raman and X-ray photoelectron spectroscopies. Films with carbon content in the 0 to 100 at.% range were prepared under the same deposition conditions used to prepare a-Ge:H films. The infrared spectra revealed that the carbon is bonded in both sp3 and sp2 configurations. XPS measurements show a chemical shift of the binding energy of the Ge 3d core electrons toward larger energies as the carbon content increases, while the line-width remains almost constant. On the other hand, the peak associated with the C 1s orbital displays a doublet related to the C–Ge and C–C bonds. The Raman spectroscopy data are analyzed over a wide frequency range of the Stokes scattering for different alloy compositions.
TL;DR: The vibrational spectra of linear BC3 and linear B2C2 in an argon matrix at 10 K have been observed for the first time by Fourier transform infrared spectroscopy.
Abstract: The vibrational spectra of linear BC3 and linear B2C2 in an argon matrix at 10 K have been observed for the first time by Fourier transform infrared spectroscopy. Mixtures of boron and carbon powders were vaporized in a resistively heated (∼3000 K) oven. BC3 was produced during codeposition of the vapors with argon onto a CsI substrate maintained at 10 K; B2C2 was observed only after annealing the matrices. Frequencies measured at 2002.1 and 1512.5 cm−1 have been assigned to the ν1(σ) and ν2(σ) B–C stretching fundamentals of linear BC3 and a frequency measured at 955.0 cm−1 has been assigned to the ν3(σu) stretching fundamental of linear symmetric BC2B. These assignments are based on FTIR measurements of the majority of the BC3 and B2C2 isotopomer frequencies and are consistent with the results from Rittby’s collaborative ab initio study.
TL;DR: In this paper, the effects of precursor gas composition and radio frequency (r.f.) power on the optical and structural properties of a-C:H/SiC-H composite thin films are investigated.
TL;DR: A new aerosol-based deposition method, for the production of sol−gel-derived films under ambient conditions, has been developed and surface segregation of the C8 moiety within the TrEOS−C8- derived films is demonstrated.
Abstract: A new aerosol-based deposition method, for the production of sol−gel-derived films under ambient conditions, has been developed. Tetraethyl orthosilicate (TEOS) and N-octyltriethoxysilane (TrEOS-C8)-derived sol−gel-processed films were produced using the new technique and compared to films produced by a conventional spin-casting approach. All films were characterized using scanning electron microscopy, profilometry, electron spectroscopy for chemical analysis (ESCA), diffuse-reflectance infrared Fourier transform spectroscopy, and steady-state fluorescence spectroscopy. Sol−gel-derived films produced using the aerosol-based method were uniform, and their thickness could be controlled between 0.6 and at least 3.0 μm. Spin casting of the neat sol−gel-processed solutions generally yielded more thick (2.0 ± 0.10 μm) films, but these thicker films were of poorer optical quality and very often more highly cracked. ESCA data demonstrate surface segregation of the C8 moiety within the TrEOS−C8-derived films. This...
TL;DR: In this paper, the chemical and microstructural properties of oxide phases precipitated from concentrated FeCl 3 solutions were investigated using 57 Fe Mossbauer spectroscopy, Fourier transform infrared (FT-IR) and transmission electron microscopy.