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Artigos de revistas sobre o assunto "IR/THz simultaneous spectroscopy"
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Chupas, Peter, Karena Chapman, Kevin Beyer, Olaf Borkiewicz e Haiyan Zhao. "Simultaneous infrared spectroscopy and X-ray PDF measurements". Acta Crystallographica Section A Foundations and Advances 70, a1 (5 de agosto de 2014): C1179. http://dx.doi.org/10.1107/s2053273314088202.
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Combining insights from diffuse reflection infrared Fourier transform spectroscopy (DRIFTS) and X-ray pair distribution function (PDF) analysis has the potential to provide deeper insight into complex materials systems under reactive conditions, including heterogeneous catalysts and host-guest systems. We have developed instrumentation and non-ambient reaction cells that enable combined PDF-IR studies without compromise to either measurement. Through careful selection of the IR spectrometer and optics, the IR instrument and reaction cell were adapted to allow angular dispersive X-ray measurements without change to the active IR components, resulting in IR data that are entirely uncompromised. The associated PDF and diffraction data are shown to be of comparable quality and resolution to standard geometry PDF/diffraction measurements. We have demonstrated this approach through the study of desorption of coordinated and non-coordinated guests from the nanoporous Prussian blue analogue MnII3[CoIII(CN)6]2(H2O)6·x{H2O}. The combined data shows how the release of guests from different sites is coupled to structural relaxation of the framework. We will also discus recent results where we have extended the approach to the study of zeolite catalysts.
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Śliwińska, Smolinski e Kucharski. "Simultaneous Analysis of Heavy Metal Concentration in Soil Samples". Applied Sciences 9, n.º 21 (4 de novembro de 2019): 4705. http://dx.doi.org/10.3390/app9214705.
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The application of Fourier transform infrared spectroscopy to the simultaneous analysis of heavy metal concentration in soil samples was demonstrated in this paper. Two spectral techniques, namely, attenuated total reflectance (ATR) and diffuse reflectance (DRIFT), were applied and the whole infrared spectral region, i.e., far IR, mid IR, and near IR were considered in this work. Spectral data with reference to the results of laboratory analysis enabled the development of calibration partial least squares (PLS) models. The PLS models for the ATR near IR were characterized by a good fit and good prediction abilities. According to the results obtained, the most accurate description and prediction were realized in the case of mid/far and near IR for the mercury and nickel concentration in soil. Application of far IR slightly improved the prediction possibilities of the model. The construction of PLS models based on the Fourier-transform infrared (FT-IR) spectra enables the perception of FT-IR spectroscopy as a supplementary method that is useful in the estimation and monitoring of the contamination level in soils.
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Pelletier, Isabelle, Christian Pellerin, D. Bruce Chase e John F. Rabolt. "New Developments in Planar Array Infrared Spectroscopy". Applied Spectroscopy 59, n.º 2 (fevereiro de 2005): 156–63. http://dx.doi.org/10.1366/0003702053085043.
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A planar array infrared (PA-IR) spectrograph offers several advantages over other infrared approaches, including high acquisition rate and sensitivity. However, it suffers from some important drawbacks, such as a limited spectral range and a significant curvature of the recorded spectral images, which still need to be addressed. In this article, we present new developments in PA-IR spectroscopy that overcome these drawbacks. First, a data processing method for the correction of the curvature observed in the spectral images has been developed and refined. In addition, a dual-beam instrument that allows the simultaneous recording of two independent spectral images has been developed. These two improvements have been combined to demonstrate the real-time background correction capability of PA-IR instruments. Finally, the accessible spectral range of the PA-IR spectrograph has been extended to cover simultaneously the methylene stretching (3200–2800 cm−1) and the fingerprint (2000–1000 cm−1) spectral regions.
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Zhu, Qianqian, Rui Zhou, Jun Liu, Jianzhong Sun e Qianqian Wang. "Recent Progress on the Characterization of Cellulose Nanomaterials by Nanoscale Infrared Spectroscopy". Nanomaterials 11, n.º 5 (20 de maio de 2021): 1353. http://dx.doi.org/10.3390/nano11051353.
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Researches of cellulose nanomaterials have seen nearly exponential growth over the past several decades for versatile applications. The characterization of nanostructural arrangement and local chemical distribution is critical to understand their role when developing cellulose materials. However, with the development of current characterization methods, the simultaneous morphological and chemical characterization of cellulose materials at nanoscale resolution is still challenging. Two fundamentally different nanoscale infrared spectroscopic techniques, namely atomic force microscope based infrared spectroscopy (AFM-IR) and infrared scattering scanning near field optical microscopy (IR s-SNOM), have been established by the integration of AFM with IR spectroscopy to realize nanoscale spatially resolved imaging for both morphological and chemical information. This review aims to summarize and highlight the recent developments in the applications of current state-of-the-art nanoscale IR spectroscopy and imaging to cellulose materials. It briefly outlines the basic principles of AFM-IR and IR s-SNOM, as well as their advantages and limitations to characterize cellulose materials. The uses of AFM-IR and IR s-SNOM for the understanding and development of cellulose materials, including cellulose nanomaterials, cellulose nanocomposites, and plant cell walls, are extensively summarized and discussed. The prospects of future developments in cellulose materials characterization are provided in the final part.
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Sullivan, David H., W. Curtis Conner e Michael P. Harold. "Surface Analysis with FT-IR Emission Spectroscopy". Applied Spectroscopy 46, n.º 5 (maio de 1992): 811–18. http://dx.doi.org/10.1366/0003702924124844.
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The technique of infrared emission spectroscopy (IRES) is reviewed and further examined in this study as a surface analysis tool. A system has been designed which allows simultaneous kinetic and in situ infrared emission analysis of catalyst surfaces. IRES spectra of several gas mixture/solid systems are obtained in order to examine sample preparation and spectra processing issues; these systems include Pt/Al2O3 exposed to CO and CO-NO mixtures, an oxidized copper plate, and a zeolite exposed to inert atmospheres. For the temperature range of importance to catalysis (300–600 K), IRES is limited to frequencies less than 2500 cm−1. However, IRES is especially well suited for studying solid-state vibrational modes (<1000 cm−1). Moreover, IRES allows catalyst samples to be studied without dilution or extensive sample preparation. The thin samples required for IRES make it possible to study both surface adsorbate and the solid-state lattice vibrations simultaneously. This information can provide useful insight into the interpretation of kinetic data of reactions on metal oxide catalysts. However, samples which are too thick or are supported on a high-emissivity surface will not yield satisfactory spectra. Two correction techniques are examined which reduce background and sample-reflectance effects in the emission spectra. Some of the IRES data are compared to the corresponding spectra obtained by transmission and diffuse-reflectance spectroscopy. IRES is shown to be competitive with these more popular techniques for IR surface analysis.
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Beyer, Kevin A., Haiyan Zhao, Olaf J. Borkiewicz, Mark A. Newton, Peter J. Chupas e Karena W. Chapman. "Simultaneous diffuse reflection infrared spectroscopy and X-ray pair distribution function measurements". Journal of Applied Crystallography 47, n.º 1 (7 de dezembro de 2013): 95–101. http://dx.doi.org/10.1107/s1600576713028410.
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Combining insights from diffuse reflection infrared Fourier transform spectroscopy and X-ray pair distribution function (PDF) analysis has the potential to deepen our understanding of complex materials systems including heterogeneous catalysts and host–guest systems. This article describes the development of instrumentation and non-ambient reaction cells that enable combined PDF–IR studies without compromise to either measurement. Through careful selection of the IR spectrometer and optics, the IR instrument and reaction cell were adapted to allow angular dispersive X-ray measurements without change to the active IR components. The PDF and diffraction data obtained with this experimental configuration are shown to be of similar quality and resolution to standard capillary-based measurements. Simultaneous combined measurements are demonstrated for desorption of guests from within a Prussian blue analog.
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Liu, Kan-Zhi, R. Anthony Shaw, Angela Man, Thomas C. Dembinski e Henry H. Mantsch. "Reagent-free, Simultaneous Determination of Serum Cholesterol in HDL and LDL by Infrared Spectroscopy". Clinical Chemistry 48, n.º 3 (1 de março de 2002): 499–506. http://dx.doi.org/10.1093/clinchem/48.3.499.
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Abstract Background: The purpose of this study was to assess the feasibility of infrared (IR) spectroscopy for the simultaneous quantification of serum LDL-cholesterol (LDL-C) and HDL-cholesterol (HDL-C) concentrations. Methods: Serum samples (n = 90) were obtained. Duplicate aliquots (5 μL) of the serum specimens were dried onto IR-transparent barium fluoride substrates, and transmission IR spectra were measured for the dry films. In parallel, the HDL-C and LDL-C concentrations were determined separately for each specimen by standard methods (the Friedewald formula for LDL-C and an automated homogeneous HDL-C assay). The proposed IR method was then developed with a partial least-squares (PLS) regression analysis to quantitatively correlate IR spectral features with the clinical analytical results for 60 randomly chosen specimens. The resulting quantification methods were then validated with the remaining 30 specimens. The PLS model for LDL-C used two spectral ranges (1700–1800 and 2800–3000 cm−1) and eight PLS factors, whereas the PLS model for HDL-C used three spectral ranges (800–1500, 1700–1800, and 2800–3500 cm−1) with six factors. Results: For the 60 specimens used to train the IR-based method, the SE between IR-predicted values and the clinical laboratory assays was 0.22 mmol/L for LDL-C and 0.15 mmol/L for HDL-C (r = 0.98 for LDL-C; r = 0.91 for HDL-C). The corresponding SEs for the test spectra were 0.34 mmol/L (r = 0.96) and 0.26 mmol/L (r = 0.82) for LDL-C and HDL-C, respectively. The precision for the IR-based assays was estimated by the SD of duplicate measurements to be 0.11 mmol/L (LDL-C) and 0.09 mmol/L (HDL-C). Conclusions: IR spectroscopy has the potential to become the clinical method of choice for quick and simultaneous determinations of LDL-C and HDL-C.
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Hazel, G., F. Bucholtz, I. D. Aggarwal, G. Nau e K. J. Ewing. "Multivariate Analysis of Mid-IR FT-IR Spectra of Hydrocarbon-Contaminated Wet Soils". Applied Spectroscopy 51, n.º 7 (julho de 1997): 984–89. http://dx.doi.org/10.1366/0003702971941359.
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This article describes a series of mid-IR FT-IR reflectance spectroscopy measurements of hydrocarbon-contaminated wet soils. The eventual goal of this work is the development of an analysis tool suitable for real-time in situ underground measurements where a suitable reference spectrum is not available. Multivariate analysis of the resulting spectral data indicates that the strongly varying wet soil matrix and the absence of a suitable reference spectrum in the field do not render this measurement technique unfeasible as a means of realizing remote in situ chemical detection in wet soils. It was also observed that simultaneous quantification of moisture content and identification of soil composition may be achieved. These results have important applications to in situ site characterization for environmental cleanup and soil characterization for construction planning.
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Shaw, R. Anthony, Steven Kotowich, Michael Leroux e Henry H. Mantsch. "Multianalyte Serum Analysis Using Mid-Infrared Spectroscopy". Annals of Clinical Biochemistry: International Journal of Laboratory Medicine 35, n.º 5 (setembro de 1998): 624–32. http://dx.doi.org/10.1177/000456329803500505.
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This study assesses the potential for using mid-infrared (mid-IR) spectroscopy of dried serum films as the basis for the simultaneous quantitation of eight serum analytes: Total protein, albumin, triglycerides, cholesterol, glucose, urea, creatinine and uric acid. Infrared transmission spectra were acquired for 300 serum samples, each analysed independently using accepted reference clinical chemical methods. Quantitation methods were based upon the infrared spectra and reference analyses for 200 specimens, and the models validated using the remaining 100 samples. Standard errors in the IR-predicted analyte levels (Sy/x) were 2.8 g/L (total protein), 2.2 g/L (albumin), 0.23 mmol/L (triglycerides), 0.28 mmol/L (cholesterol), 0.41 mmol/L (glucose) and 1.1 mmol/L for urea, with correlation coefficients (IR vs reference analyses) of 0.95 or better. The IR method emerged to be less suited for creatinine (S y/ x = μmol/L) and uric acid (S y/x = 140 μmol/L) due to the relatively low concentrations typical of these analytes.
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Manning, Christopher J., e Peter R. Griffiths. "Step-Scanning Interferometer with Digital Signal Processing". Applied Spectroscopy 47, n.º 9 (setembro de 1993): 1345–49. http://dx.doi.org/10.1366/0003702934067630.
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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.
Teses / dissertações sobre o assunto "IR/THz simultaneous spectroscopy"
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Tchana, betnga Wilfried. "Développement d'instrumentation pour une spectroscopie simultanée THz et IR : application à l'équilibre de HONO". Electronic Thesis or Diss., Université Paris Cité, 2023. http://www.theses.fr/2023UNIP7134.
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La mesure des concentrations d'espèces traces, susceptibles d'avoir un impact notable sur la santé, le climat ou la stabilité de la couche d'ozone constitue un véritable défi. Les prochaines missions spatiales, prévues à haute sensibilité (FORUM et IASI-NG), apporteront un progrès seulement si les paramètres spectraux nécessaires sont disponibles. Pour certaines espèces réactives, telles que l'acide nitreux (HONO) et l'acide hypobromeux (HOBr), les données spectroscopiques sont incomplètes ou quasiment inexistantes. Le défi dans cette thèse consiste à obtenir des paramètres spectroscopiques quantitatifs pour ces espèces. Pour atteindre cet objectif, un dispositif instrumental novateur impliquant l'utilisation simultanée de deux instruments, une expérience IR/THz, a été construit : une cellule thermostatée (200-350K) conçue en matériaux inertes, verre et téflon, est combinée à un spectromètre THz dans la région 0.1-1.1 THz et un spectromètre à Transformée de Fourier (FTS) à haute résolution (HR) dans le domaine IR. Le spectromètre THz permet de sélectionner plusieurs raies purement rotationnelles de la molécule cible pour la détermination de la pression partielle et le FTS la mesure simultanée du spectre rovibrationnel dans une fenêtre atmosphérique IR utilisable pour la quantification de l'espèce d'intérêt. La stratégie s'appuie donc sur le fait que les intensités des raies de rotation pure dépendent uniquement du moment dipolaire moléculaire, qui est connu avec précision à partir de mesures existantes par effet Stark. Dans le cas de HONO qui n'existe au laboratoire que sous la forme d'un équilibre avec H2O, NO et NO2, la méconnaissance de la pression partielle dans le mélange gazeux entraîne de sérieuses difficultés pour effectuer des mesures quantitatives. De plus, HONO possède deux formes isomériques et la hauteur de la barrière d'isomérisation entre le cis- et le trans-HONO DeltaCis-Trans est encore mal connue, ce qui affecte les positions et surtout les intensités de raies. Pour obtenir une valeur plus précise de cette barrière, des spectres ont été enregistrés à HR dans la gamme 50 - 200 cm-1, à 3 températures (240, 270 et 296 K), en utilisant le rayonnement synchrotron de la ligne AILES à SOLEIL. Des modélisations précises ont été effectuées et ont permis de déterminer la hauteur de la barrière DeltaCis-Trans = 95.8 ± 9.2 cm-1. Notre valeur est en bon accord avec la détermination précédente de Sironneau et al. (99 ± 25 cm-1) mais nous avons amélioré la précision d'un facteur 2.6. Nous avons utilisé cette nouvelle valeur de DeltaCis-Trans et les paramètres du moment dipolaire pour un calcul du spectre synthétique. Une liste de raies précise dans la région de l'IR lointain (0 - 200 cm-1) incluant les positions et intensités absolues a été compilée et s'est avérée plus robuste pour une meilleure détection de HONO dans les objets astrophysiques. Pour la détermination des intensités absolues dans la région IR moyen où HONO est actuellement détectée, des spectres simultanés IR/THz ont été enregistrés au LISA en utilisant l'instrumentation innovante développée durant cette thèse. Une première modélisation de ces spectres est présentée dans cette thèse et in fine, il en découlera une liste de raies pour HONO dans la région 730 - 920 cm-1 qui sera fourni à la communauté scientifique via les bases de données HITRAN et GEISA et exploitée dans l'analyse des observations satellitaires. Concernant HOBr, l'objectif sera de compiler une base de données spectroscopiques dans l'IR vers 8.6 um qui sera utilisée par IASI-NG et FORUM pour une détection et quantification dans l'atmosphère terrestre. Notons que HOBr joue un rôle important dans la chimie atmosphérique et n'existe au laboratoire que dans un mélange caractérisé par l'équilibre chimique : H2O + Br2O = 2(HOBr). La méthodologie et les outils expérimentaux développés durant cette thèse sont un atout pour la mise en oeuvre de ce projet qui, constitue les perspectives de ce travailMeasuring trace gases having a notable impact on human health, climate and the stability of the ozone layer constitutes an extremely important challenge. In the coming years, new, higher sensitivity satellite instruments will improve atmospheric sounding only if the necessary spectral parameters are available. For some species of atmospheric interest such as nitrous acid (HONO) and hypobromous acid (HOBr), spectroscopic data are incomplete or almost non-existent. The challenge in this thesis is to get quantitative spectroscopic parameters for these species. To achieve this objective, an innovative instrumental set-up involving the simultaneous use of two instruments, an IR/THz dual beam experiment, has been built: a thermostatically controlled cell (200-350K) made of inert materials, glass and Teflon, capable of accommodating a 0.1-1.1 THz spectrometer and coupled to a high resolution (HR) Fourier Transform spectrometer (FTS) in the IR range. The THz spectrometer allows to select rotational lines of the target molecule for partial pressure determination, and the FTS enables simultaneous measurement of the rovibrational spectrum in an IR atmospheric window for quantification of the species of interest. The adopted strategy relies on the fact that the intensities of the rotational spectra simply depend on the permanent dipole moment of the molecule of interest, determined with high accuracy from Stark effect measurements. In the case of HONO, which only exists in laboratory conditions in the form of an equilibrium mixture with other species like H2O, NO and NO2, the lack of knowledge of the partial pressure in the gas mixture leads to serious difficulties for quantitative measurements. In addition, HONO exists in two conformer forms, and the height of the conformer barrier between cis- and trans-HONO DeltaCis-Trans is still poorly known, which affects lines positions and especially lines intensities. To improve the determination of the energy difference between the ground vibrational state of the cis- and trans-HONO conformers of HONO, high resolution spectra were recorded in the 50-200 cm-1 spectral region at three different temperatures (240, 270 and 296 K), using the synchrotron radiation of the AILES beamline at SOLEIL. Precise modelling has been performed and were used to determine the height of the conformer barrier DeltaCis-Trans = 95.8 ± 9.2 cm-1. Our value is in good agreement with the previous determination by Sironneau et al (99 ± 25 cm-1), but we have improved the accuracy of this determination by a factor of 2.6. We used this new value of DeltaCis-Trans and the dipole moment parameters for a synthetic spectrum calculation. A precise line list in the far-IR region (0 - 200 cm-1), including positions and absolute lines intensities was generated and, proved to be more robust for an improved detection of HONO in astrophysical objects. To determine absolute intensities in the mid-IR region where HONO is currently detected, simultaneous IR/THz spectra were recorded at LISA using innovative instrumentation developed during this thesis. A first modelling of these spectra is presented in this thesis, and in fine will lead to a much more precise line list for HONO in the 730 - 920 cm-1 region, which will be provided to the scientific community via the HITRAN and GEISA databases and used in the analysis of satellite observations. Regarding HOBr, the aim will be to generate a spectroscopic database in the IR region around 8.6 um, to be used by IASI-NG and FORUM for detection and quantification in the Earth's atmosphere. HOBr plays an important role in atmospheric chemistry and, only exists in laboratory conditions in a mixture characterized by chemical equilibrium: H2O + Br2O = 2(HOBr). The methodology and experimental tools developed during this thesis will be an advantage for implementation of this project, which constitutes the outlook for this work
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Pezzotti, Simone. "DFT-MD simulations and theoretical SFG spectroscopy to characterize H-Bonded networks at aqueous interfaces : from hydrophobic to hydrophilic environments Structural definition of the BIL and DL: a new universal methodology to rationalize non-linear χ(2)(ω) SFG signals at charged interfaces, including χ(3)(ω) contributions What the Diffuse Layer (DL) Reveals in Non-Linear SFG Spectroscopy 2D H-Bond Network as the Topmost Skin to the Air-Water Interface Combining ab-initio and classical molecular dynamics simulations to unravel the structure of the 2D-HB-network at the air-water interface 2D-HB-Network at the air-water interface: A structural and dynamical characterization by means of ab initio and classical molecular dynamics simulations Spectroscopic BIL-SFG Invariance Hides the Chaotropic Effect of Protons at the Air-Water Interface Molecular hydrophobicity at a macroscopically hydrophilic surface Graph theory for automatic structural recognition in molecular dynamics simulations DFT-MD of the (110)-Co3O4 cobalt oxide semiconductor in contact with liquid water, preliminary chemical and physical insights into the electrochemical environment". Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLE008.
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Améliorer notre connaissance de la structure de l'eau dans l'environnement spécial offert par une interface est essentiel pour la compréhension de nombreux phénomènes naturels et applications technologiques. Pour révéler cette structure interfaciale de l'eau, des techniques capables de fournir des informations microscopiques, de manière sélective, pour cette couche interfaciale (BIL) sont nécessaires. Dans le présent travail de thèse, nous avons donc étudié les interfaces aqueuses au niveau moléculaire, en couplant la modélisation théorique à partir de simulations DFT-MD avec les spectroscopies SFG et THz-IR. En développant de nouveaux protocoles/outils d'investigation associant simulations DFT-MD et spectroscopie SFG, en particulier pour la rationalisation plus complexe des interfaces chargées, nous avons fourni une compréhension globale de l'effet des conditions interfaciales d'hydrophilicité, de pH, de force ionique sur le réseau des liaisons-H formé dans la couche interfaciale BIL, sur ses signatures spectroscopiques et sur son impact sur les propriétés physico-chimiques. Nous avons montré pour la première fois que, dans des conditions suffisamment hydrophobes, l'eau interfaciale crée des réseaux des liaisons-H bidimensionnels, révélé expérimentalement par les spectres THz-IR. Le réseau-2D dicte la dynamique de l'eau interfaciale, le potentiel de surface, l'acidité de surface, la tension superficielle et la thermodynamique d'hydratation des solutés hydrophobes. Cet "ordre horizontal" aux interfaces hydrophobes est opposé à "l'ordre verticale" obtenu aux interfaces hydrophiles. Nous avons aussi révélé comment les ions et les conditions de pH modifient ces arrangements structurauxImproving our knowledge on water H-Bonded networks formed in the special environment offered by an interface is pivotal for our understanding of many natural phenomena and technological applications. To reveal the interfacial water arrangement, techniques able to provide detailed microscopic information selectively for the interfacial layer are required. In the present thesis work, we have hence investigated aqueous interfaces at the molecular level, by coupling theoretical modeling from DFT-MD simulations with SFG & THz-IR spectroscopies. By developing new investigation protocols/tools, coupling DFT-MD simulations and SFG spectroscopy, in particular for the more complex rationalization of charged interfaces, we have provided a global comprehension of the effect of various interfacial conditions (hydrophilicity, pH, ionic strength) on the HB-Network formed in the interfacial layer (BIL), on its spectroscopic signatures and on its impact on physico-chemical properties. We have shown for the first time that, in sufficiently hydrophobic conditions, BIL interfacial water creates special 2-Dimensional HB-Networks, experimentally revealed by one specific THz-IR marker band. Such 2D-network dictates HBs and orientational dynamics of interfacial water, surface potential, surface acidity, water surface tension and thermodynamics of hydration of hydrophobic solutes. Such "horizontal ordering” of water at hydrophobic interfaces is found opposite to the “vertical ordering” of water at hydrophilic interfaces, while coexistence of the two orders leads to disordered interfacial water in intermediate hydrophilic/hydrophobic conditions. Both DFT-MD and SFG further revealed how ions & pH conditions alter these BIL-water orders
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Garet, Frédéric. "Génération optoélectronique d'impulsions électromagnétiques ultra-courtes : application à la spectroscopie THz". Grenoble INPG, 1997. http://www.theses.fr/1997INPG0175.
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Nous presentons la construction et l'utilisation d'une experience de spectroscopie terahertz pour la caracterisation de materiaux dans le domaine sub-millimetrique, les mesures etant realisees dans le domaine temporel. Dans une premiere partie, nous decrivons tout d'abord l'experience dediee a la generation et a la mesure d'impulsions electromagnetiques (em) ultracourtes. Nous employons des photocommutateurs sur substrat de lt-gaas excites par une impulsion laser de 100 fs de duree, et utilises comme dipole de hertz. Nous obtenons ainsi des impulsions em de durees voisines de la picoseconde et dont les spectres s'etendent de quelques dizaines de ghz a plus de 2 thz. Pour caracteriser un materiau, ce dernier est positionne entre les antennes emettrice et receptrice. On mesure ainsi sa fonction de transfert temporelle. Par transformee de fourier numerique, on calcule son coefficient de transmission frequentiel, dont on deduit l'indice de refraction et l'absorption intrinseque du materiau. Nous presentons des resultats de caracterisation pour differents cas rencontres en pratique : echantillons optiquement epais, fins (dont les films minces sur un substrat), materiaux anisotropes. Pour traiter tous ces cas, nous proposons une methode originale d'extraction des parametres materiaux. Nous montrons aussi que l'epaisseur precise des echantillons peut etre simultanement deduite de ces mesures. Cette technique peut aussi etre utilisee pour une etude dynamique de materiaux. Nous avons construit une experience pompe (optique) - sonde (thz). Nous avons teste plusieurs materiaux semi-conducteurs, et compare les resultats avec ceux obtenus avec une experience pompe - sonde tout optique. Nous analysons ces resultats, en particulier pour des echantillons de semi-conducteurs iii-v.
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Lin, Wei-Chen, e 林威呈. "A new approach for simultaneous characterization of the material's permittivity and permeability by THz time-domain spectroscopy". Thesis, 2014. http://ndltd.ncl.edu.tw/handle/39400506040474816320.
Texto completo da fonteCapítulos de livros sobre o assunto "IR/THz simultaneous spectroscopy"
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Vittone, A., C. Rossi, E. Covino e F. Giovannelli. "High S/N simultaneous optical and IR spectrophotometric observations of Herbig Ae/Be stars". In The Impact of Very High S/N Spectroscopy on Stellar Physics, 109–15. Dordrecht: Springer Netherlands, 1988. http://dx.doi.org/10.1007/978-94-009-2937-1_20.
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Raghavendra Babu, N., Malothu Narender, Y. Padmavathi, A. Narmada e P. Ravi Kumar. "A Novel Fourier Transform Infrared Spectrophotometric Method for Quantitative Analysis of Irbesartan and Hydrochlorthiazide in Fixed Dose Formulations". In Current Trends in Drug Discovery, Development and Delivery (CTD4-2022), 268–82. Royal Society of Chemistry, 2023. http://dx.doi.org/10.1039/9781837671090-00268.
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The development of reliable Fourier transform infrared (FTIR) instrumentation has made IR spectroscopy a more widely used technique for quantitative analysis. Qualitative organic compound identification has always been its strength. IRB and HTZ were estimated simultaneously in pharmaceutical dosage forms using a new FTIR spectroscopic approach. The approach involves KBr pelletization of IRB and HTZ and direct measurement with a reduced path length cell. In absorbance mode, the instrument gathered infrared spectra with 8cm-1 resolution. IR peaks changed after baseline adjustment. The strong, unambiguous, and proportionate carbonyl (C=O) and amine (N-H) functional groups of IRB and HTZ at 1733cm-1 and 3361cm-1 were chosen for quantitative measurement. IRB concentrations from 60-300μg/mg and HTZ concentrations from 5-25μg/mg followed Beer Lambert’s law. ICH guidelines validated the methodology. A statistical t-test was used to compare the results of the new FTIR method to the outcomes of the current UV method, and the results showed no statistically significant difference between the two ways at p=0.05.From the current study’s findings, it can be inferred that the simultaneous estimation method for IRB and HTZ is simple, accurate, and cost-effective. The proposed method can be successfully used to estimate IRB and HTZ simultaneously in pure and pharmaceutical dosage forms.
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Brovko, Oleksandr O., Natalia V. Yarova, Tetiana F. Samoilenko e Larysa M. Yashchenko. "Mutual sensibilization in epoxyacrylate interpenetrating polymer networks". In NEW FUNCTIONAL SUBSTANCES AND MATERIALS FOR CHEMICAL ENGINEERING, 149–58. PH “Akademperiodyka”, 2021. http://dx.doi.org/10.15407/akademperiodyka.444.149.
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Using the method of IR spectroscopy, the kinetic features of the course of photoinitiated cationic and free radical polymerization in simultaneous epoxyacrylate interpenetrating polymer networks were investigated. The degree and rate of conversion of epoxy groups in the epoxy component (aliphatic diepoxide UP-650D, aliphatic-alicyclic triepoxide UP-650T, and diane epoxides ED-20 and Epicot 828), and the opening of double bonds in acrylate component (triethylene glycol dimethacrylate) were determined. The sensitizing effect of the acrylate component on the degree of conversion of epoxy groups in IPNs with aliphatic diepoxide or aliphatic-alicyclic triepoxide with an epoxy/acrylate ratio of 50/50 wt. % was revealed. For diane epoxies, the opposite regularity of conversion of epoxy groups in the composition of epoxy-acrylate IPNs is observed: in comparison with initial polymer networks, the degree of conversion of epoxy groups was significantly reduced. In the first case of low-viscosity aliphatic and cycloaliphatic epoxides such a sensitization is occurred due to the fact that the simultaneous polymerization of acrylate via a free radical mechanism promotes the decomposition of the photoinitiator and the formation of more macrocations quantity. In second case of more viscous diane epoxy resins, the spatial restriction imposed by the rapidly formed acrylate networks is predominate. That is why the conversion of epoxy groups is reduced and this effect is neutralized.
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Kumar Mitra, Rajib, e Dipak Kumar Palit. "Probing Biological Water Using Terahertz Absorption Spectroscopy". In Terahertz Technology [Working Title]. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.97603.
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Hydrogen bonding properties of water molecules, which are confined in microcavities of biological interfaces, are significantly different from those of bulk water and drive most of the complex biological processes. While NMR, X-ray and UV–vis-IR spectroscopic techniques have been found inadequate for describing the dynamics of the thick (20–40 Å) sheath of hydration layer around biomolecules, recently developed THz spectroscopy has emerged as a powerful technique to directly probe the collective dynamics of hydrogen bonds in the hydration layer, which control all important functions of the biomolecules in life. Both laser and accelerator-based THz sources are intense enough to penetrate up to about 100 μm thick water samples, which makes THz transmission and/or dielectric relaxation measurements possible in aqueous solutions. These measurements provide valuable information about the rattling and rotational motions of hydrated ions, making, breaking and rearrangement of hydrogen bonds in hydration layer as well as hydrophilic and hydrophobic interactions between biomolecule and water. THz spectroscopy has also been successfully applied to study the effect of modulation of the physical conditions, like temperature, pH, concentration of proteins and chemical additives, on the structure and dynamics of hydration layer. THz spectroscopy has also been applied to study the processes of denaturation, unfolding and aggregation of biomolecules.
Trabalhos de conferências sobre o assunto "IR/THz simultaneous spectroscopy"
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Vasilyev, Sergey, Mike Mirov, Sergey Mirov e Konstantin Vodopyanov. "Video-Rate Broadband Longwave IR Dual-Comb Spectroscopy with Cr:ZnS lasers". In Applied Industrial Spectroscopy. Washington, D.C.: Optica Publishing Group, 2023. http://dx.doi.org/10.1364/ais.2023.jth3a.1.
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Cr:ZnS comb sources uniquely combine few-optical-cycle pulses with multi-Watt power and ultra-low intensity noise enabling LWIR and THz spectroscopy systems that simultaneously access all the advantages of the dual comb method.
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Cristescu, S. M., K. E. Jahromi, A. Khodabakhsh, V. Bosman, F. J. M. Harren, M. K. Dasa, E. Rokx, H. Martin e M. Nematollahi. "Volatiles detection using broadband mid-IR spectroscopy: from a research idea to application in fruit storage facilities". In Applied Industrial Spectroscopy. Washington, D.C.: Optica Publishing Group, 2023. http://dx.doi.org/10.1364/ais.2023.atu5a.2.
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A broadband mid-infrared gas sensor using a supercontinuum light source is developed for simultaneous multispecies detection. We present the journey from a laboratory setup towards a market-ready prototype for application in fruit storage facilities.
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Lo, Michael K. F., Jay Anderson, Eoghan P. Dillon, Mustafa Kansiz e Curtis A. Marcott. "Submicron Noncontact Simultaneous Infrared and Raman Spectroscopy for Challenging Failure Analysis". In ISTFA 2021. ASM International, 2021. http://dx.doi.org/10.31399/asm.cp.istfa2021p0196.
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Abstract This paper discusses the use of optical photothermal infrared (O-PTIR) spectroscopy combined with Raman analysis. The new technique overcomes many of the limitations of conventional FTIR and Raman spectroscopy when used alone. It is based on an infrared-visible pump-probe system that incorporates a wavelength-tunable IR laser that emits a pulsed beam that is combined colinearly with the output of a 532-nm green laser. As the paper explains, infrared radiation is partially absorbed by the test target when the wavelength of the laser resonates with the vibrational mode of the material. This excitation process causes the area under the infrared spot to heat up, in turn, causing local expansion along with changes in the refractive indices. These photothermal effects cycle on and off in synch with the pulsed IR beam and the amplitudes of the on-off states are captured by the co-located visible beam and plotted as a function of wavelength over the tunable range of the IR laser. The diffraction limited spot size of the visible beam is approximately 416 nm, corresponding to a spatial resolution of about 1 μm, which is 30 times more precise than conventional FTIR. In addition, by measuring photothermal effects in localized regions, it is possible to identify chemicals in quantities of matter as small as 0.4 pg. By comparison, the sensitivity of transmission mode FTIR is significantly less at around 100 pg.
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Anderson, Jay, Mustafa Kansiz, Michael Lo e Curtis Marcott. "Submicron Simultaneous IR and Raman Spectroscopy (IR+Raman): Breakthrough Developments in Optical Photothermal IR (O-PTIR) Combined for Enhanced Failure Analysis". In ISTFA 2019. ASM International, 2019. http://dx.doi.org/10.31399/asm.cp.istfa2019p0292.
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Abstract Failure analysis of organics at the microscopic scale is an increasingly important requirement, with traditional analytical tools such as FTIR and Raman microscopy, having significant limitations in either spatial resolution or data quality. We introduce here a new method of obtaining Infrared microspectroscopic information, at the submicron level in reflection (far-field) mode, called Optical-Photothermal Infrared (O-PTIR) spectroscopy, that can also generate simultaneous Raman spectra, from the same spot, at the same time and with the same spatial resolution. This novel combination of these two correlative techniques can be considered to be complimentary and confirmatory, in which the IR confirms the Raman result and vice-versa, to yield more accurate and therefore more confident organic unknowns analysis.
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Hojer, S., H. Ahlberg, S. Lundqvist, J. Davidsson e L. Holmlid. "IR Tunable Diode Laser Absorption Spectroscopy in an no Seeded Molecular Beam". In Laser Applications to Chemical Analysis. Washington, D.C.: Optica Publishing Group, 1987. http://dx.doi.org/10.1364/laca.1987.tha4.
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In many experiments involving molecular beams for fundamental studies of e.g. chemical reactions in crossed beams [1,2], so called seeded beams are used. In such a beam a few percent of the desired molecule is mixed in an excess of light driver gas. This accelerates the heavier seed molecules, and also cools the translational, rotational, and vibrational degrees of freedom of the molecules. The translational acceleration and simultaneous cooling in the beam can be studied by molecular beam techniques coupled to mass spectroscopy, like rapid mechanical chopping and molecular time-of-flight measurements. The rotational and vibrational temperatures are much harder to determined in an ordinary molecular apparatus, and some optical spectroscopic method is usually needed [3,4,5].
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Weeks, Reagan R. D., Ryan T. Rhoades, Seth E. Erickson, Sivanandan S. Harilal, Mark C. Phillips e R. Jason Jones. "Multi-Wavelength Dual-Comb Spectroscopy of Laser-Produced Plasmas in the Near-IR". In CLEO: Science and Innovations. Washington, D.C.: Optica Publishing Group, 2022. http://dx.doi.org/10.1364/cleo_si.2022.sm3f.4.
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Using the supercontinuum and second harmonic from a dual-comb spectrometer, simultaneous time-resolved absorption measurements of rubidium atomic transitions originating from ground and highly-excited states in the NIR (1529 nm) are obtained following a laser-produced plasma.
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Shaw, R. A., U. I. Tuor, T. Foniok, S. Bascaramurty, K. Ringland, E. McKenzie, M. Qiao, B. Tomanek e H. H. Mantsch. "Simultaneous Near-IR Spectroscopy and Magnetic Resonance Imaging to Assess Cerebral Oxygenation and Brain Water during Hypoxia-Ischemia in 2-week-old Rats". In European Conference on Biomedical Optics. Washington, D.C.: Optica Publishing Group, 2001. http://dx.doi.org/10.1364/ecbo.2001.4432_57.
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Cerebral near-infrared spectroscopy can potentially probe several parameters related to the onset of stroke and the ensuing tissue damage. One obvious marker of ischemia is cerebral oxygenation, which can be lowered sharply in stroke-affected tissue. Also commonly assessed, though less straightforward to recover, is the redox state of the cytochrome aa3 copper center. Finally, parameters that are in principle available but seldom recovered from in vivo near-IR spectra are changes in water concentration and scattering properties of the tissue. We have evaluated the potential for near-IR spectroscopy to detect relevant changes in cerebral oxygenation, blood volume, water content, and scattering properties in an infant rat stroke model that is well characterized by magnetic resonance imaging methods. The specific aim was to acquire near-IR spectra simultaneously with MR images and to correlate stroke-associated changes detected via these two modalities prior to, during and after a hypoxia-ischemia episode within this stroke model. Presented here are results from the design and testing of a near-IR illumination/detection system that is compatible with an MR imaging system, and the recovery of trends in the near-IR spectra that complement the hypoxic-ischemic changes observed in the MR images. Unexpectedly large intensity changes observed for the in vivo near-IR water absorptions are ascribed to hypoxia-induced variations in effective optical pathlength, suggesting that the water absorptions may prove generally useful as a means to track such changes.
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Jay Anderson, D., Mustafa Kansiz, Michael Lo, Eoghan Dillon e Curtis Marcott. "Enhanced Failure Analysis (FA) of Organic Contamination Using Submicron Simultaneous IR and Raman Spectroscopy: Breakthrough Developments of Optical Photothermal IR (O-PTIR)". In ISTFA 2020. ASM International, 2020. http://dx.doi.org/10.31399/asm.cp.istfa2020p0075.
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Abstract Rapid identification of organic contamination in the semi and semi related industry is a major concern for research and manufacturing. Organic contamination can affect a system or subsystem’s performance and cause premature failure of the product. As an example, in February 2019 the Taiwan Semiconductor Manufacturing Company (TMSC), a major semiconductor manufacturer, reported that a photoresist it used included a specific element which was abnormally treated, creating a foreign polymer in the photoresist resulting in an estimated loss of $550M [1].
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Pal, Mithun, Nancy Faßheber, Andreas Petersen, Franko Greiner e Gernot Friedrichs. "Optical detection of C4H2 in an Ar/C2H2 dusty plasma using mid-IR ICL-based frequency modulation spectroscopy". In Optical Sensors. Washington, D.C.: Optica Publishing Group, 2023. http://dx.doi.org/10.1364/sensors.2023.stu2d.7.
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An ICL-based mid-IR frequency modulation absorption spectrometer around 3 µm has been developed. It was tested and deployed for simultaneous monitoring of the temporal dynamics of C2H2 and C4H2 in a low pressure plasma discharge.
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Goldstein, Neil, Brian Gregor, Jamine Lee, Stephen K. Kramer, Stuart Kozola e Kenneth J. Semega. "IR Structured Emission-Based Speciation, Thermometry, and Tomography of CO and H2O in High-Pressure Combustors". In ASME Turbo Expo 2006: Power for Land, Sea, and Air. ASMEDC, 2006. http://dx.doi.org/10.1115/gt2006-90899.
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Passive optical probes and high-resolution emission spectroscopy are used to provide a general-purpose real-time temperature and chemical species sensing capability. Probes can be inserted in the combustor, at the turbine inlet, in the augmenter, or at the engine exit with application as an engine development diagnostic tool that provides spatially resolved measurements of the key combustion parameters: temperature, CO concentration, and H2O concentration. Multiple probes are arrayed to collect the emitted infrared radiation over different views of the hot gas path. Line-of-sight averaged concentrations and temperatures are determined by spectral analysis of the emitted radiation along each line of sight (LOS). Spatial profiles may also be determined by simultaneous analysis of overlapping lines of sight. The collected infrared spectra contain optically thin and optically thick features that reflect the effects of emission and absorption within the combustion region. The known spectral structure of the component spectra can be used for the automated interpretation of the observed radiance spectra in terms of concentrations and temperatures along the line of sight, and in specific volume elements of overlapping lines of sight. In this work, we present measurements of atmospheric-pressure flames and high-pressure combustors and describe the formalism for fitting the observed spectra to a basis of simulated spectra to extract estimates of concentrations and temperatures. The spectral basis is constructed using a multilayer radiation transport model, in which each line-of-sight or measurement volume is divided into segments of uniform concentration and temperature. The observed radiance emanating from each segment is calculated as a function of the local physical variables. The collection of observed data, which contains a highly structured emission spectrum over each line of sight, is fit to the spectral basis to extract line-of-sight averaged physical properties, or in the case of spatial reconstruction, volume-averaged properties for each of the overlap regions.
Relatórios de organizações sobre o assunto "IR/THz simultaneous spectroscopy"
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Agassi, Menahem, Michael J. Singer, Eyal Ben-Dor, Naftaly Goldshleger, Donald Rundquist, Dan Blumberg e Yoram Benyamini. Developing Remote Sensing Based-Techniques for the Evaluation of Soil Infiltration Rate and Surface Roughness. United States Department of Agriculture, novembro de 2001. http://dx.doi.org/10.32747/2001.7586479.bard.
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The objective of this one-year project was to show whether a significant correlation can be established between the decreasing infiltration rate of the soil, during simulated rainstorm, and a following increase in the reflectance of the crusting soil. The project was supposed to be conducted under laboratory conditions, using at least three types of soils from each country. The general goal of this work was to develop a method for measuring the soil infiltration rate in-situ, solely from the reflectance readings, using a spectrometer. Loss of rain and irrigation water from cultivated fields is a matter of great concern, especially in arid, semi-arid regions, e.g. much of Israel and vast area in US, where water is a limiting factor for crop production. A major reason for runoff of rain and overhead irrigation water is the structural crust that is generated over a bare soils surface during rainfall or overhead irrigation events and reduces its infiltration rate (IR), considerably. IR data is essential for predicting the amount of percolating rainwater and runoff. Available information on in situ infiltration rate and crust strength is necessary for the farmers to consider: when it is necessary to cultivate for breaking the soil crust, crust strength and seedlings emergence, precision farming, etc. To date, soil IR is measured in the laboratory and in small-scale field plots, using rainfall simulators. This method is tedious and consumes considerable resources. Therefore, an available, non-destructive-in situ methods for soil IR and soil crusting levels evaluations, are essential for the verification of infiltration and runoff models and the evaluation of the amount of available water in the soil. In this research, soil samples from the US and Israel were subjected to simulated rainstorms of increasing levels of cumulative energies, during which IR (crusting levels) were measured. The soils from the US were studied simultaneously in the US and in Israel in order to compare the effect of the methodology on the results. The soil surface reflectance was remotely measured, using laboratory and portable spectrometers in the VIS-NIR and SWIR spectral region (0.4-2.5mm). A correlation coefficient spectra in which the wavelength, consisting of the higher correlation, was selected to hold the highest linear correlation between the spectroscopy and the infiltration rate. There does not appear to be a single wavelength that will be best for all soils. The results with the six soils in both countries indeed showed that there is a significant correlation between the infiltration rate of crusted soils and their reflectance values. Regarding the wavelength with the highest correlation for each soil, it is likely that either a combined analysis with more then one wavelength or several "best" wavelengths will be found that will provide useful data on soil surface condition and infiltration rate. The product of this work will serve as a model for predicting infiltration rate and crusting levels solely from the reflectance readings. Developing the aforementioned methodologies will allow increased utilization of rain and irrigation water, reduced runoff, floods and soil erosion hazards, reduced seedlings emergence problems and increased plants stand and yields.