Showing papers on "Fourier transform spectroscopy published in 2009"
TL;DR: In this article, the authors used laser frequency combs as the light source of Fourier transform spectroscopy (FTS) to record well-resolved broadband absorption and dispersion spectra in a single experiment.
Abstract: Molecular fingerprinting using absorption spectroscopy is a powerful analytical method, particularly in the infrared, the region of intense spectral signatures Fourier transform spectroscopy—the widely used and essential tool for broadband spectroscopy—enables the recording of multi-octave-spanning spectra, exhibiting 100 MHz resolution with an accuracy of 1 × 10−9 and 1 × 10−2 in wavenumber and intensity determination, respectively Typically, 1 × 106 independent spectral elements may be measured simultaneously within a few hours, with only average sensitivity Here, we show that by using laser frequency combs as the light source of Fourier transform spectroscopy it is possible to record well-resolved broadband absorption and dispersion spectra in a single experiment, from the beating signatures of neighbouring comb lines in the interferogram The sensitivity is thus expected to increase by several orders of magnitude Experimental proof of principle is here carried out on the 15-µm overtone bands of acetylene, spanning 80 nm with a resolution of 15 GHz Consequently, without any optical modification, the performance of Fourier spectrometers may be drastically boosted By using an optical frequency comb as the light source for Fourier transform spectroscopy, scientists show that well-resolved broadband absorption and dispersion spectra can be recorded in a single experiment, providing sensitive detection of multiple molecular species over a broad spectral window
292 citations
TL;DR: In this article, X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, field emission scanning electron microscopy (FESEM), TEM, HRTEM, photoluminescence (PL) spectra, kinetic decay, and electron paramagnetic resonance (EPR) were used to characterize the obtained Ca5(PO4)3OH samples.
Abstract: Hydroxyapatite (Ca5(PO4)3OH) nano- and microcrystals with multiform morphologies (separated nanowires, nanorods, microspheres, microflowers, and microsheets) have been successfully synthesized by a facile hydrothermal process. X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), photoluminescence (PL) spectra, kinetic decay, and electron paramagnetic resonance (EPR) were used to characterize the samples. The experimental results indicate that the obtained Ca5(PO4)3OH samples show an intense and bright blue emission under long-wavelength UV light excitation. This blue emission might result from the CO2•− radical impurities in the crystal lattice. Furthermore, the organic additive (trisodium citrate) and pH values have an obvious impact on the morphologies and luminescence properties of the products to some degree. The possible formation ...
271 citations
TL;DR: In this paper, a novel synthesis of nanoparticles Ni and NiO using thermal decomposition and their physicochemical characterization was presented, where the nanoparticles were prepared using [bis(2-hydroxyacetophenato)nickel(II)] as precursor.
258 citations
TL;DR: In this article, the structural properties of the modified ferrites and the magnetic fluids were characterized by XRD (X-ray powder diffraction), TEM (transmission electron microscopy), DRIFTS (diffusion reflectance infrared Fourier transform spectroscopy), FTNIR (Fourier transform near-infrared), UV−vis, normal Raman spectrograms, and surfaceenhanced Raman scattering (SERS).
Abstract: Ferrites of the type MIIFe2O4 (M = Fe and Co) have been prepared by the traditional coprecipitation method. These ferrites were modified by the adsorption of fatty acids derived from soybean and castor oil and were then dispersed in cyclohexane, providing very stable magnetic fluids, readily usable in nonpolar media. The structural properties of the ferrites and modified ferrites as well as the magnetic fluids were characterized by XRD (X-ray powder diffraction), TEM (transmission electron microscopy), DRIFTS (diffusion reflectance infrared Fourier transform spectroscopy), FTNIR (Fourier transform near-infrared), UV−vis, normal Raman spectroscopy, and surface-enhanced Raman scattering (SERS). XRD and TEM analysis have shown that the magnetic nanoparticles (nonmodified and modified) present diameters in the range of 10−15 nm. DRIFTS measurements have shown that the carboxylate groups of soybean and castor oil fatty acids adsorb on the ferrite surface, forming three different structures: a bridging bidentat...
199 citations
TL;DR: Several demonstrations of two-dimensional Fourier-transform spectroscopy are presented, including an example of a phase-cycling scheme that reduces noise and a spectrum that accesses two-quantum coherences, where all excitation pulses require phase locking for detection of the signal.
Abstract: The JILA multidimensional optical nonlinear spectrometer (JILA-MONSTR) is a robust, ultrastable platform consisting of nested and folded Michelson interferometers that can be actively phase stabilized. This platform generates a square of identical laser pulses that can be adjusted to have arbitrary time delay between them while maintaining phase stability. The JILA-MONSTR provides output pulses for nonlinear excitation of materials and phase-stabilized reference pulses for heterodyne detection of the induced signal. This arrangement is ideal for performing coherent optical experiments, such as multidimensional Fourier-transform spectroscopy, which records the phase of the nonlinear signal as a function of the time delay between several of the excitation pulses. The resulting multidimensional spectrum is obtained from a Fourier transform. This spectrum can resolve, separate, and isolate coherent contributions to the light-matter interactions associated with electronic excitation at optical frequencies. To show the versatility of the JILA-MONSTR, several demonstrations of two-dimensional Fourier-transform spectroscopy are presented, including an example of a phase-cycling scheme that reduces noise. Also shown is a spectrum that accesses two-quantum coherences, where all excitation pulses require phase locking for detection of the signal.
162 citations
TL;DR: In this paper, the authors used zinc oxalate as a precursor to prepare zinc oxide nanotriangles by thermal decomposition and added triphenylphosphine, and oleylamine to control the particle size.
134 citations
TL;DR: It is demonstrated that the spectrum at any point is a weighted sum of the sample reflection and transmission and that the dominance of the reflection spectrum in optically dense regions can account for some of the spectral distortions previously attributed to dispersion artefacts.
Abstract: Fourier transform infrared spectra of a single cell in transflection geometry are seen to vary significantly with position on the cell, showing a distorted derivative-like lineshape in the region of the optically dense nucleus. A similar behaviour is observable in a model system of the protein albumin doped in a potassium bromide disk. It is demonstrated that the spectrum at any point is a weighted sum of the sample reflection and transmission and that the dominance of the reflection spectrum in optically dense regions can account for some of the spectral distortions previously attributed to dispersion artefacts. Rather than being an artefact, the reflection contribution is ever present in transflection spectra and it is further demonstrated that the reflection characteristics can be used for cellular mapping.
125 citations
TL;DR: The JILA Multidimensional Optical Nonlinear SpecTRometer (JILA-MONSTR) as mentioned in this paper is a robust, ultra-stable platform consisting nested and folded Michelson interferometers that can be actively phase stabilized.
Abstract: The JILA Multidimensional Optical Nonlinear SpecTRometer (JILA-MONSTR) is a robust, ultra-stable platform consisting nested and folded Michelson interferometers that can be actively phase stabilized. This platform generates a square of identical laser pulses that can be adjusted to have arbitrary time delay between them, while maintaining phase stability. The JILA-MONSTR provides output pulses for nonlinear excitation of materials and phase-stabilized reference pulses for heterodyne detection of the induced signal. This arrangement is ideal for performing coherent optical experiments, such as multidimensional Fourier-transform spectroscopy, which records the phase of the nonlinear signal as a function of the time delay between several of the excitation pulses. The resulting multidimensional spectrum is obtained from a Fourier transform. This spectrum can resolve, separate and isolate coherent contributions to the light-matter interactions associated with electronic excitation at optical frequencies. To show the versatility of the JILA-MONSTR, several demonstrations of two-dimensional Fourier-transform spectroscopy are presented, including an example of a phase-cycling scheme that reduces noise.
123 citations
TL;DR: In this paper, the authors report results on the measurements of the absorption cross section of SO2 in the UV/visible region at high resolution and that investigates high temperatures in support to planetary applications.
Abstract: This paper is the second of a series that reports results on the measurements of the absorption cross section of SO2 in the UV/visible region at high resolution and that investigates high temperatures in support to planetary applications. Absorption cross sections of SO2 have been obtained in the 29 000–44 000 cm−1 spectral range (227–345 nm) with a Fourier transform spectrometer at a resolution of 2 cm−1 (0.4500 cm MOPD and boxcar apodisation). Pure SO2 samples were used and measurements were performed at room temperature (298 K) as well as at 318, 338 and 358 K. Temperature effects in this spectral region are investigated and are favorably compared to existing studies in the literature. Comparison of the absorption cross section at room temperature shows good agreement in intensity with most of the literature data, but shows that most of the latter suffer from inaccurate wavelength scale definition. Moreover, literature data are often given only on restricted spectral intervals. Combined with the data described in the first part of this series of papers on SO2, this new data set offers the considerable advantage of covering the large spectral interval extending from 24 000 to 44 000 cm−1 (227–420 nm), at the four temperatures investigated.
122 citations
TL;DR: Wurtzite ZnS nanorods have been synthesized via a hydrothermal technique by adding thioglycolic acid with zinc acetate as the precursor.
109 citations
TL;DR: In this paper, the interlocked cubes of hausmannite Mn3O4 thin films were synthesized by simple, inexpensive, and low temperature chemical route from urea containing bath These films were characterized by using X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM), Fourier transform infrared spectra (FT-IR), optical absorption and wettability test.
TL;DR: First evidence of free-induction decay from a scatterer composed of parts coupled by near-fields is reported, possible only with broadband illumination, and offers a new, unique tool to discriminate against background scattering artifacts.
Abstract: We demonstrate continuous infrared spectra from 20 nm sample spots, by combining dispersive Fourier-transform infrared spectroscopy (FTIR) with scattering near-field microscopy (s-SNOM). With the “apertureless” tip of a standard AFM cantilever in one arm of a Michelson interferometer the spectra arise simultaneously in amplitude and phase. The effect of near-field phonon resonance of SiC is used to verify background-free s-SNOM operation, and to determine the absolute scattering efficiency, at 6 cm−1 spectral resolution. We further report first evidence of free-induction decay from a scatterer composed of parts coupled by near-fields. This is possible only with broadband illumination. It offers a new, unique tool to discriminate against background scattering artifacts.
TL;DR: The combination of the micrometer size and non-destructive nature of the techniques together with the high resolution and brilliance of the synchrotron radiation has proved to be a procedure most advantageous for the study of reaction, aging and degradation processes.
TL;DR: 2D Fourier transform electronic spectroscopy obtained in the pump-probe geometry using a continuum probe and demonstrates the method on a simple dye system exhibiting vibrational wavepacket dynamics that modulate the peak shapes of the 2D spectra.
Abstract: We report 2D Fourier transform electronic spectroscopy obtained in the pump–probe geometry using a continuum probe. An acousto-optic pulse shaper placed in the pump arm of a standard pump-continuum probe experiment permits 2D spectroscopy that probes a broad spectral range. We demonstrate the method on a simple dye system exhibiting vibrational wavepacket dynamics that modulate the peak shapes of the 2D spectra. The broad spectral range of the continuum probe allows us to observe vibronic cross peaks in the 2D spectra.
TL;DR: Two-dimensional ultrafast fourier transform spectroscopy in the deep ultraviolet is demonstrated using an acousto-optic modulator based pulse shaper and measurements on the DNA nucleobase Adenine are presented.
Abstract: We demonstrate two-dimensional ultrafast fourier transform spectroscopy in the deep ultraviolet (~260 nm) using an acousto-optic modulator based pulse shaper. The use of a pulse shaper in the ultraviolet allows for rapid scanning, high phase (time) stability (~0.017 rad) and phase cycling. We present measurements on the DNA nucleobase Adenine.
TL;DR: The one-step synthesis and spectroscopic characterizations of size-controlled silver nanoparticles are described and it is shown that spherical nanoclusters of 7.52 +/- 0.57 nm were produced and these values compare very well with the typical values of carboxylate-protected Ag nanoparticles.
Abstract: The one-step synthesis and spectroscopic characterizations of size-controlled silver nanoparticles are described. The transmission electron microscopy (TEM), nuclear magnetic resonance (NMR), Fourier transform infrared spectroscopy (FT-IR), thermal gravimetric-mass analysis (TGA-MS) and X-ray photoelectron spectroscopy (XPS) techniques were used to characterize the decanoate-protected silver nanoparticles. TEM analysis showed that spherical nanoclusters of 7.52 ± 0.57 nm were produced. Furthermore, the particle sizes are uniform with a narrow size distribution. For all samples, Ag 3d5/2 and 3d3/2 components appeared at 368.5 and 374.5 eV, respectively, in the XPS spectrum; these values compare very well with the typical values of carboxylate-protected Ag nanoparticles. A thermal analysis mass spectrometer was used to analyze the desorption behavior of decanoate-protected nanoparticles. From the desorption maximum temperatures of 181 and 263 °C, activation energies of 27.2 and 32.2 kcal mol−1 for the desorption processes in the Ag MPCs were obtained, assuming a first-order reaction and using a pre-exponential factor of 1 × 1013 s−1. A specific resistivity of 6.097 μΩ cm for the silver metal film (0.7 μm) on a Si wafer can be produced simply by thermal annealing of an Ag monolayer-protected clusters film under an atmosphere of 90% N2–10% H2 at 300 °C for 1 h.
TL;DR: Three-dimensional electronic Fourier transform spectroscopy of GaAs quantum wells using four fully phase-coherent, noncollinear optical fields is demonstrated and a calibration procedure for the carrier frequency yields biexciton binding energy values with high accuracy.
Abstract: We demonstrate three-dimensional (3D) electronic Fourier transform spectroscopy of GaAs quantum wells using four fully phase-coherent, noncollinear optical fields. Since the full complex signal field is measured as a function of all three time intervals, nearly every peak in the resulting 3D spectral solid arises from a distinguishable sequence of transitions represented by a single Feynman pathway. We use the 3D spectral peaks to separate two pathways involving weakly bound mixed biexcitons generated in different time orders. In the process, we reveal a peak that was previously obscured by a correlated but unbound exciton pair coherence. We also demonstrate a calibration procedure for the carrier frequency which yields biexciton binding energy values with high accuracy.
TL;DR: In this article, the thermal transition behavior, optical and structural properties of spin-coated P3HT:C 60 blended films with different C 60 ratios were investigated using differential scanning calorimetry (DSC), thermo-gravimetric analysis (TGA), ultraviolet-visible (UV-vis) spectroscopy, photoluminescence (PL), Fourier transform infrared absorption (FT-IR) spectrograms and Raman spectrogram.
TL;DR: In this paper, a uniform Al2O3 films were deposited on silicon substrates by the sol-gel process from stable coating solutions and the technological procedure includes spin coating deposition and investigating the influence of the annealing temperature on the dielectric properties.
TL;DR: The graphitic layered compound C6N9H3 as discussed by the authors was prepared by reaction between melamine and cyanuric chloride under high pressure-high temperature condition in a piston cylinder apparatus and characterised using SEM, powderX-ray diffraction, UV Raman and near-IR Fourier transform Raman spectroscopy with near IR excitation.
TL;DR: In this paper, superparamagnetic magnetite/polystyrene (PS) composite particles were prepared by inverse emulsion polymerization with water-based ferrofluid as dispersing phase and organic solvent and styrene (St) as continuous phase.
TL;DR: In this article, the growth, composition and morphology of HfO2 films that have been deposited by atomic layer deposition (ALD) are examined in two different ALD chemistries.
TL;DR: In this article, single-crystal X-ray diffraction was used to identify functional groups of dl -malic acid-doped ammonium dihydrogen phosphate.
TL;DR: An imaging spectrometer based on a Fabry-Perot interferometer is presented, which has the advantage of a compact, high numerical aperture, high luminosity hyperspectral imaging device.
Abstract: An imaging spectrometer based on a Fabry-Perot interferometer is presented. The Fabry-Perot interferometer scans the mirror distance up to contact and the intensity modulated light signal is transformed using a Fourier Transform based algorithm, as the Michelson based Fourier Transform Spectrometers does. The resulting instrument has the advantage of a compact, high numerical aperture, high luminosity hyperspectral imaging device. Theory of operation is described along with one experimental realization and preliminary results.
TL;DR: Application of the TMDS-algorithm to processing data on the Suwannee River FA has proven its unique capacities in analysis of spectra with high peak density and opens new horizons in unfolding molecular complexity of NOM and other natural products.
Abstract: The ultrahigh-resolution Fourier transform ion cyclotron resonance (FTICR) mass spectrum of natural organic matter (NOM) contains several thousand peaks with dozens of molecules matching the same nominal mass. Such a complexity poses a significant challenge for automatic data interpretation, in which the most difficult task is molecular formula assignment, especially in the case of heavy and/or multielement ions. In this study, a new universal algorithm for automatic treatment of FTICR mass spectra of NOM and humic substances based on total mass difference statistics (TMDS) has been developed and implemented. The algorithm enables a blind search for unknown building blocks (instead of a priori known ones) by revealing repetitive patterns present in spectra. In this respect, it differs from all previously developed approaches. This algorithm was implemented in designing FIRAN-software for fully automated analysis of mass data with high peak density. The specific feature of FIRAN is its ability to assign formulas to heavy and/or multielement molecules using "virtual elements" approach. To verify the approach, it was used for processing mass spectra of sodium polystyrene sulfonate (PSS, M(w) = 2200 Da) and polymethacrylate (PMA, M(w) = 3290 Da) which produce heavy multielement and multiply-charged ions. Application of TMDS identified unambiguously monomers present in the polymers consistent with their structure: C(8)H(7)SO(3)Na for PSS and C(4)H(6)O(2) for PMA. It also allowed unambiguous formula assignment to all multiply-charged peaks including the heaviest peak in PMA spectrum at mass 4025.6625 with charge state 6- (mass bias -0.33 ppm). Application of the TMDS-algorithm to processing data on the Suwannee River FA has proven its unique capacities in analysis of spectra with high peak density: it has not only identified the known small building blocks in the structure of FA such as CH(2), H(2), C(2)H(2)O, O but the heavier unit at 154.027 amu. The latter was identified for the first time and assigned a formula C(7)H(6)O(4) consistent with the structure of dihydroxyl-benzoic acids. The presence of these compounds in the structure of FA has so far been numerically suggested but never proven directly. It was concluded that application of the TMDS-algorithm opens new horizons in unfolding molecular complexity of NOM and other natural products.
TL;DR: In this paper, NiAl-layered double hydroxides (LDH) were successfully synthesized by a straightforward one-pot hydrothermal method using Ni(II) glycinate complex as a chemical precursor under extremely high basic conditions and soft Hydrothermal conditions.
Abstract: Flower-like NiAl-layered double hydroxides (LDH) were successfully synthesized by a straightforward one-pot hydrothermal method using Ni(II) glycinate complex as a chemical precursor under extremely high basic conditions and soft hydrothermal conditions. Systematic screening of synthesis parameters such as reaction time and hydrothermal process temperature was carried out. The materials have been thoroughly characterized via a set of techniques including X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, chemical analysis, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and thermal gravimetric analysis (TG). The results demonstrate that a too long reaction time value disrupts the flower-like microspheres and a too high temperature value is deleterious for the LDH structure. Transition mixed oxides with the same flower-like morphology were readily obtained by thermal treatment at a moderate temperature of the above LDH precursors.
TL;DR: Fourier transform infrared spectroscopy was used to discriminate important wood-destroying fungi and resulted in 95% correctly classified spectra, demonstrating the high potential of this method for fungal strain identification.
Abstract: Fourier transform infrared spectroscopy (FTIR) was used to discriminate important wood-destroying fungi. Mycelia of 26 fungal strains belonging to 24 different species were grown on agar plates and subjected to FTIR attenuated total reflection (ATR) measurements. To classify the FTIR spectra, cluster analysis – an unsupervised multivariate data analysis method – was compared with artificial neural network (ANN) analysis – a supervised approach. By internal validation, both methods classified 99% of the spectra correctly. External validation with independent test set spectra resulted in 95% correctly classified spectra, demonstrating the high potential of this method for fungal strain identification.
TL;DR: In this article, single crystals of the nonlinear optical material, l-arginine bis(trifluoroacetate), with dimensions of 32 × 21 × 4 mm3 were grown by the temperature-lowering method from its aqueous solution.
Abstract: Single crystals of the nonlinear optical material, l-arginine bis(trifluoroacetate), with dimensions of 32 × 21 × 4 mm3 were grown by the temperature-lowering method from its aqueous solution. The crystal structure was determined using X-ray single-crystal diffraction at 93 K. X-ray powder diffraction, Fourier transform infrared, and Raman spectroscopic investigations were used to characterize the grown crystal. Morphological analysis reveals that the crystal is a rhombohedron with the major forms of (001), (101), and (100). UV−visible−NIR absorption spectrum and second harmonic generation were investigated to explore its characteristic optical features. Thermogravimetric (TG), differential thermal analysis (DTA), derivative thermogravimetric (DTG), and differential scanning calorimetry (DSC) studies were carried out to characterize the thermal behaviors of the grown crystals. In addition, the specific heat at low temperature and thermal expansion coefficients along the principal axes were determined. I...
TL;DR: In this article, a facile solvothermal process was used to prep rare-earth ion (Eu3+, Ce3+, Tb3+) particles with oval morphology without further heat treatment.
TL;DR: Several two-dimensional projections are shown and techniques to isolate different contributions to the coherent response of semiconductors are demonstrated, which reveal previously unobserved many-body correlations.
Abstract: We demonstrate optical two-dimensional Fourier transform spectroscopy of heavy- and light-hole excitons in GaAs quantum wells. This is enabled by active interferometric stabilization of the excitation pulse separation and of a reference pulse.