Artículos de revistas: "THz simultaneous spectroscopy"

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Yamaguchi, Masashi, Minfeng Wang y Pablo Suarez. "TERAHERTZ PHONON-POLARITON IMAGING FOR THE APPLICATION OF CHEMICAL DETECTION". International Journal of High Speed Electronics and Systems 17, n.º 02 (junio de 2007): 355–65. http://dx.doi.org/10.1142/s0129156407004552.

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A combination of Terahertz (THz) polariton spectroscopy and polariton imaging technique for the application to chemical sensing is presented. We use phonon-polaritons, a coupled oscillation of the lattice vibration and radiation field, as an intense radiation source for THz spectroscopy. The propagation process of the polaritons generated in one of the two LiNbO 3 transducer crystals through the sample sandwiched between the crystals is visualized using a polariton imaging technique. Partially reflected polaritons at the transducer-sample interface and polaritons partially transmitted through the sample are visualized simultaneously in a single frame of an image. The temporal profile of reflected and transmitted phonon-polaritons can be obtained without scanning the delay time between the pump and probe femtosecond laser pulses unlike THz time-domain spectroscopy which requires point-by-point acquisition of the temporal pulse profile using conventional pump-probe scheme. The results suggest possible application of this technique to the chemical sensing with fast acquisition rate. The technique has been successfully applied to the measurement of liquid and solid samples, and simultaneous measurement of multiple samples has also been achieved.

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Oishi, Shingo, Yasuto Hijikata, Hiroyuki Yaguchi y Sadafumi Yoshida. "Simultaneous Determination of the Carrier Concentration, Mobility and Thickness of SiC Homo-Epilayers Using Terahertz Reflectance Spectroscopy". Materials Science Forum 556-557 (septiembre de 2007): 423–26. http://dx.doi.org/10.4028/www.scientific.net/msf.556-557.423.

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We have simultaneously determined the carrier concentration, mobility, and thickness of 4H-SiC homo-epilayers with carrier concentration of 1016–1018 cm-3 from reflectance spectroscopy in the wavenumber range of 20–2000 cm-1. The spectra at 20–100 cm-1 and at 80–2000 cm-1 were measured by using the terahertz time domain spectrometer (THz-TDS) and the Fourier-transform infrared (FTIR) spectrometer, respectively. A modified classical dielectric function (MDF) model was employed for the curve fitting. We have compared the values of free carrier concentrations estimated from the reflectance spectroscopy with the net doping concentrations obtained from C–V measurements, and have discussed the validity of the electrical properties estimated from the reflectance spectroscopy.

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Denisov, Grigory, Irina Zotova, Ilya Zheleznov, Andrey Malkin, Alexander Sergeev, Roman Rozental y Mikhail Glyavin. "Towards Watt-Level THz Sources for High-Resolution Spectroscopy Based on 5th-Harmonic Multiplication in Gyrotrons". Applied Sciences 12, n.º 22 (9 de noviembre de 2022): 11370. http://dx.doi.org/10.3390/app122211370.

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We propose the concept of high-power THz radiation sources based on five-fold frequency multiplication in gyrotrons intended for plasma applications. The efficient excitation at the 5th cyclotron harmonic is due to the specific property of the eigenmodes of cylindrical waveguides, as a result of which, the conditions of simultaneous electrodynamic resonance at two selected TE modes are satisfied asymptotically with very high accuracy. Previously, we have verified this principle in experiments with a low-frequency kilowatt-level gyrotron in which, due to the low-density spectrum, the operating mode is excited with no competition from parasitic oscillations. The novel concept is a development of this idea applied to the systems with a denser spectrum, which is inevitable in higher frequency and power devices. Simulations within the averaged time-domain model demonstrate that, despite the mode competition, it is possible to excite Watt-level 1.25 THz 5th cyclotron harmonic in a recently developed sub-MW 0.25 THz gyrotron with TE19,8 operating mode. The obtained results open a possibility for implementation of radiation sources with output power/frequency combination, practically inaccessible using other THz generation methods and highly sought for a number of applications, including high-resolution molecular spectroscopy.

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Ferrante, Carino, Leonardo Lucchesi, Alessia Cemmi, Ilaria Di Sarcina, Jessica Scifo, Adriano Verna, Andrea Taschin et al. "Gamma Irradiation Effect on Polymeric Chains of Epoxy Adhesive". Polymers 16, n.º 9 (25 de abril de 2024): 1202. http://dx.doi.org/10.3390/polym16091202.

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The study of materials for space exploration is one of the most interesting targets of international space agencies. An essential tool for realizing light junctions is epoxy adhesive (EA), which provides an elastic and robust material with a complex mesh of polymeric chains and crosslinks. In this work, a study of the structural and chemical modification of a commercial two-part flexible EA (3M™ Scotch-Weld™ EC-2216 B/A Gray), induced by 60Co gamma radiation, is presented. Combining different spectroscopic techniques, such as the spectroscopic Fourier transform infrared spectroscopy (FTIR), the THz time-domain spectroscopy (TDS), and the electron paramagnetic resonance (EPR), a characterization of the EA response in different regions of the electromagnetic spectrum is performed, providing valuable information about the structural and chemical properties of the polymers before and after irradiation. A simultaneous dissociation of polymeric chain and crosslinking formation is observed.The polymer is not subject to structural modification at an absorbed dose of 10 kGy, in which only transient free radicals are observed. Differently, between 100 and 500 kGy, a gradual chemical degradation of the samples is observed together with a broad and long-living EPR signal appearance. This study also provides a microscopic characterization of the material useful for the mechanism evaluation of system degradation.

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Huang, Hsin-hui, Takeshi Nagashima, Tetsu Yonezawa, Yasutaka Matsuo, Soon Hock Ng, Saulius Juodkazis y Koji Hatanaka. "Giant Enhancement of THz Wave Emission under Double-Pulse Excitation of Thin Water Flow". Applied Sciences 10, n.º 6 (17 de marzo de 2020): 2031. http://dx.doi.org/10.3390/app10062031.

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Simultaneous measurements of THz wave and hard X-ray emission from thin and flat water flow when irradiated by double femtosecond laser pulses (800 nm, 35 fs/transform-limited, 0.5 kHz, delay times up to 15 ns) were carried out. THz wave measurements by time-domain spectroscopy and X-ray detection by Geiger counters were performed at the transmission and the reflection sides of the flow. THz wave emission spectra show their dynamic peak shifts toward the low frequency with the highest intensity enhancements more than 1.5 × 10 3 times in |E| 2 accumulated over the whole spectrum range of 0–3 THz at the delay time of 4.7 ns between the two pulses. On the other hand, X-ray intensity enhancements are limited to about 20 times at 0 ns under the same experimental conditions. The mechanisms for the spectral changes and the intensity enhancements in THz wave emission are discussed from the viewpoint of laser ablation on the water flow induced by the pre-pulse irradiation.

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Huang, Hsin-hui, Takeshi Nagashima, Wei-hung Hsu, Saulius Juodkazis y Koji Hatanaka. "Dual THz Wave and X-ray Generation from a Water Film under Femtosecond Laser Excitation". Nanomaterials 8, n.º 7 (13 de julio de 2018): 523. http://dx.doi.org/10.3390/nano8070523.

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Simultaneous emission of the THz wave and hard X-ray from thin water free-flow was induced by the irradiation of tightly-focused femtosecond laser pulses (35 fs, 800 nm, 500 Hz) in air. Intensity measurements of the THz wave and X-ray were carried out at the same time with time-domain spectroscopy (TDS) based on electro-optic sampling with a ZnTe(110) crystal and a Geiger counter, respectively. Intensity profiles of the THz wave and X-ray emission as a function of the solution flow position along the incident laser axis at the laser focus show that the profile width of the THz wave is broader than that of the X-ray. Furthermore, the profiles of the THz wave measured in reflection and transmission directions show different features and indicate that THz wave emission is, under single-pulse excitation, induced mainly in laser-induced plasma on the water flow surface. Under double-pulse excitation with a time separation of 4.6 ns, 5–10 times enhancements of THz wave emission were observed. Such dual light sources can be used to characterise materials, as well as to reveal the sequence of material modifications under intense laser pulses.

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7

Gokus, Tobias. "Nano-FTIR Correlation Nanoscopy for Organic and Inorganic Material Analysis". ECS Meeting Abstracts MA2022-01, n.º 7 (7 de julio de 2022): 622. http://dx.doi.org/10.1149/ma2022-017622mtgabs.

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Significance: Correlation scanning probe techniques to complement nanoscale IR measurements for next generation sample characterization Scattering-type Scanning Near-field Optical Microscopy (s-SNOM) is a scanning probe approach to optical microscopy and spectroscopy, bypassing the ubiquitous diffraction limit of light to achieve a spatial resolution below 20 nanometers. s-SNOM employs the strong confinement of light at the apex of a sharp metallic atomic force microscopy (AFM) tip to create a nanoscale optical hot-spot. Analyzing the scattered light from the tip enables the extraction of the optical properties of the sample directly below the tip and yields nanoscale resolved images simultaneous to topography [1]. In addition, the technology has been advanced to enable Fourier-Transform Infrared Spectroscopy on the nanoscale (nano-FTIR) [2] using broadband radiation from the visible spectral range to THz frequencies. Recently, the combined analysis of complex nanoscale material systems by correlating near-field optical data with information obtained by other scanning probe microscopy (SPM)-based measurement methodologies has gained significant interest. For example, the material-characteristic nano-FTIR spectra of a phase-separated polystyrene/low-density polyethylene (PS/LDPE) polymer blend verifies sharp material interfaces by measuring a line profile across a ca. 1 μm sized LDPE island. Near-field reflection/absorption imaging at 1500cm-1 of the ca. 50nm thin film allows to selectively highlight the distribution of PS in the blend and simultaneously map the mechanical properties like adhesion of the different materials [3,4]. Further, we present results that correlate the near-field optical response of semiconducting samples like graphene (2D) or functional SRAM devices (3D) in different frequency ranges (mid-IR & THz) to Kelvin Probe Force Microscopy (KPFM) measurements. Thus, s-SNOM systems represent an ideal platform to gain novel insights into complex material systems by different near-field and AFM-based method. [1] F. Keilmann, R. Hillenbrand, Phil. Trans. R. Soc. Lond. A 362, 787 (2004). [2] F. Huth, et al., Nano Lett. 12, 3973 (2012). [3] B. Pollard, et al., Beilstein J. of Nanotechn. 7, 605 (2016). [4] I. Amenabar, et al., Nature Commun. 8, 14402 (2017).

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8

Lan, Yang, Benjamin J. Dringoli, David A. Valverde-Chávez, Carlito S. Ponseca, Mark Sutton, Yihui He, Mercouri G. Kanatzidis y David G. Cooke. "Ultrafast correlated charge and lattice motion in a hybrid metal halide perovskite". Science Advances 5, n.º 5 (mayo de 2019): eaaw5558. http://dx.doi.org/10.1126/sciadv.aaw5558.

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Hybrid organic-inorganic halide perovskites have shown remarkable optoelectronic properties, exhibiting an impressive tolerance to defects believed to originate from correlated motion of charge carriers and the polar lattice forming large polarons. Few experimental techniques are capable of directly probing these correlations, requiring simultaneous sub–millielectron volt energy and femtosecond temporal resolution after absorption of a photon. Here, we use time-resolved multi-THz spectroscopy, sensitive to the internal excitations of the polaron, to temporally and energetically resolve the coherent coupling of charges to longitudinal optical phonons in single-crystal CH3NH3PbI3 (MAPI). We observe room temperature intraband quantum beats arising from the coherent displacement of charge from the coupled phonon cloud. Our measurements provide strong evidence for the existence of polarons in MAPI at room temperature, suggesting that electron/hole-phonon coupling is a defining aspect of the hybrid metal-halide perovskites contributing to the protection from scattering and enhanced carrier lifetimes that define their usefulness in devices.

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9

Viščor, Petr y Martin Viščor. "Electrical Impedance Spectroscopy: “First Principles” analysis and simulations of electrical response in the classical range of frequencies below 1 THz and the resulting new role of Electrical Impedance Spectroscopy in electrical characterisation within Condensed Matter Physics". Pure and Applied Chemistry 91, n.º 11 (26 de noviembre de 2019): 1837–56. http://dx.doi.org/10.1515/pac-2018-1107.

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Abstract In order to investigate the full potential of the Electrical Impedance Spectroscopy (EIS) when used to address various aspects of conductive and dielectric response within the field of Condensed Matter Physics and Electrochemistry, a new analysis of the electrical impedance experiments has been undertaken. Within the framework of quantum mechanical band structure and using the concept of electrochemical potential for each of the relevant energies, the problem of electrical response in condensed phase has been formulated, using augmented Maxwell equations of Classical Electrodynamics, as a boundary value problem of a set of coupled, non-linear parabolic equations in energy, space and time. The result of this numerical analysis is a principal possibility of a complete electrical characterisation of both monocrystals, glassy solids and liquids. The EIS has been put in this way on a new qualitative level and should be considered now as the most general electrical experimental characterisation tool available. In this article, a methodology of numerical simulations of electrical response in condensed matter systems at classical frequencies (from ~1 THz down to dc) is presented and the numerical simulation results are then discussed, using monocrystalline Silicon, chalcogenide glass ion conductor Agx(AsS2)1−x and simple aqueous chloride solution as experimental test cases. Some other unique results of the new EIS analysis will also be discussed. These include the possibility of a clear distinction between the contribution to the electrical response from bound and mobile electrical charges, the possibility of simultaneous and independent determination of the mobile electrical charges mobility and their density in one EIS experiment and incorporation of the interfacial regions of the system under test (SUT) as an essential part of the overall electrical response.

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Grychtol, P., N. Kohlstrunk, J. Buck, S. Thiess, V. Vardanyan, D. Doblas-Jimenez, J. Ohnesorge et al. "The SXP instrument at the European XFEL". Journal of Physics: Conference Series 2380, n.º 1 (1 de diciembre de 2022): 012043. http://dx.doi.org/10.1088/1742-6596/2380/1/012043.

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Abstract The successful implementation of the baseline instruments at the European XFEL has triggered a second phase of instrument developments aiming to extend the portfolio of available techniques. At the soft X-ray undulator (SASE 3), the Soft X-ray Port (SXP) instrument is currently under construction. Conceived as an open port, it focuses primarily on femtosecond time-resolved X-ray photoelectron spectroscopy (TR-XPES), which has proven to be a powerful tool to understand the properties of materials and the interaction between their internal degrees of freedom. The extension of this technique to the soft X-ray energy range is only possible at MHz free electron lasers (FELs) due to space-charge effects which limit the maximum photon flux per pulse on the sample. In this contribution, the SXP instrument at the European XFEL and the implementation of TR-XPES using a momentum microscope are presented. The photon energy range available at SASE 3, 0.25 keV to 3.5 keV, and the variable polarization will allow for the simultaneous characterization of the electronic, magnetic, chemical and structural properties of materials with femtosecond time resolution. To this end, a wide range of laser excitation wavelengths, ranging from the XUV to the THz region, will be available.

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Tan, Chao, Dongsheng Yang, Saibo Yu, Ke Li, Haifeng Tan, Hongmei Fan, Shitai Wang et al. "Effect and Mechanism of High-Pressure Processing: A Case Study of Flue-Cured Tobacco". Beiträge zur Tabakforschung International/Contributions to Tobacco Research 27, n.º 7 (1 de septiembre de 2017): 168–81. http://dx.doi.org/10.1515/cttr-2017-0017.

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Summary After a high-pressure processing (HPP) treatment sensory evaluation of flue-cured tobacco showed modifications. There was no significant difference (P > 0.05) between the routine chemical components (total sugar, reducing sugar, nicotine, and total nitrogen) of flue-cured tobacco after high-pressure processing treatment (HPP sample) and that of an untreated control group (CG). An overall judgement, which can be made from the observations of scanning electron microscopy (SEM), X-ray computed microtomography (micro-CT) and transmission electron microscopy (TEM), is that HPP could compress the inner tunnel and tissue gap in a flue-cured tobacco leaf. However, the ultrastructure, such as the cellular cytoskeleton, would not be changed. Compared with CG, the apparent density of the HPP sample rose by 19.3%, while the true density only rose by 1.4%. This also explained that the main effect of high-pressure processing on flue-cured tobacco was microstructure compression rather than compression on the ultrastructure level. The differences between the lamina (leaf-shaped) sample, which were caused by high-pressure processing, were reflected in terahertz time-domain spectroscopy (THz-TDS), simultaneous thermal analysis (STA), and pyrolysis gas chromatography/mass spectrometry (Py-GC/MS). When the same tests were carried out using a sample that was milled to a powder, however, these differences were nearly removed. The milling process destroyed most of the microstructure of the flue-cured tobacco lamina; therefore, the results of THz-TDS, STA, and Py-GC/MS confirmed the hypothesis: That 400 MPa high-pressure processing treatment minimally changes the ultrastructure of flue-cured tobacco and only changes its relatively larger microstructure.

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Pascale, Lise, Marco Truccato, Lorenza Operti y Angelo Agostino. "Effect of Al and Ca co-doping, in the presence of Te, in superconducting YBCO whiskers growth". Acta Crystallographica Section B Structural Science, Crystal Engineering and Materials 72, n.º 5 (16 de septiembre de 2016): 702–8. http://dx.doi.org/10.1107/s2052520616009823.

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High-Tcsuperconducting cuprates (HTSC) such as YBa2Cu3O7 − x(YBCO) are promising candidates for solid-state THz applications based on stacks of intrinsic Josephson junctions (IJJs) with atomic thickness. In view of future exploitation of IJJs, high-quality superconducting YBCO tape-like single crystals (whiskers) have been synthesized from Ca–Al-doped precursors in the presence of Te. The main aim of this paper is to determine the importance of the simultaneous use of Al, Te and Ca in promoting YBCO whiskers growth with good superconducting properties (Tc= 79–84 K). Further, single-crystal X-ray diffraction (SC-XRD) refinements of tetragonal YBCO whiskers (P4/mmm) are reported to fill the literature lack of YBCO structure investigations. All the as-grown whiskers have also been investigated by means of X-ray powder diffraction (XRPD), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). Our results demonstrate that the interplay of Ca, Te and Al elements is clearly necessary in order to obtain superconducting YBCO whiskers. The data obtained from SC-XRD analyses confirm the highly crystalline nature of the whiskers grown. Ca and Al enter the structure by replacing the Y and the octahedral coordinated Cu1 site, respectively, as in other similar orthorhombic compounds, while Te does not enter the structure of whiskers but its presence in the precursor is essential to the growth of the crystals.

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Comodi, Paola, Fabio Cera, Sabrina Nazzareni y Leonid Dubrovinsky. "Raman spectroscopy of the 10-A phase at simultaneously HP-HT". European Journal of Mineralogy 19, n.º 5 (7 de noviembre de 2007): 623–29. http://dx.doi.org/10.1127/0935-1221/2007/0019-1753.

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Chen, Pin, J. C. Pearson, Herbert M. Pickett, Shuji Matsuura y Geoffrey A. Blake. "Measurements of 14NH3 in the ν2=1 state by a solid-state, photomixing, THz spectrometer, and a simultaneous analysis of the microwave, terahertz, and infrared transitions between the ground and ν2 inversion–rotation levels". Journal of Molecular Spectroscopy 236, n.º 1 (marzo de 2006): 116–26. http://dx.doi.org/10.1016/j.jms.2006.01.002.

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Guo, Quan, Yuan Zhang, Zhihui Lyu, Dongwen Zhang, Yindong Huang, Chao Meng, Zengxiu Zhao y Jianmin Yuan. "THz Time-Domain Spectroscopic Ellipsometry With Simultaneous Measurements of Orthogonal Polarizations". IEEE Transactions on Terahertz Science and Technology 9, n.º 4 (julio de 2019): 422–29. http://dx.doi.org/10.1109/tthz.2019.2921200.

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Shimoyama, Yuhei y Hiroshi Watari. "Multiple Harmonic Electron Paramagnetic Resonance Spectroscopy by Simultaneous Detection". Applied Spectroscopy 43, n.º 6 (agosto de 1989): 1021–26. http://dx.doi.org/10.1366/0003702894203840.

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A simultaneous measurement method was developed to permit the multiple detection of the first- and second-order harmonic displays of electron paramagnetic resonance (EPR) spectra. Application of integration and differentiation of amplitude and phase simultaneously, i.e., vector operations on the various displays, enables identification of signals expressed by the various harmonics. By using simultaneous detection, we found for the first time that signals indicated by the different displays are not always identical. The transformation from the first to the second harmonic displays (or vice versa) by vector operations indicated that the displays were not interchangeable when nonlinear response was involved. Simultaneous detection proved to be useful for measurements of the electron spin relaxation where multiple signals coexist. The present detection system provides a means for multivector EPR spectroscopy.

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Finger, Raphael, Thomas C. Hansen y Holger Kohlmann. "Simultaneous neutron powder diffraction and Raman spectroscopy – an approach of combining two complementary techniques". Zeitschrift für Kristallographie - Crystalline Materials 236, n.º 11-12 (22 de noviembre de 2021): 325–28. http://dx.doi.org/10.1515/zkri-2021-2051.

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Abstract Diffraction techniques are well-established methods for crystal structure determination as well as phase identification and quantification. Raman spectroscopy can be a valuable complementary characterization technique, because in contrast to the former it yields also information on amorphous materials and it is a probe for short-range structural effects. The herein presented setup allows for simultaneous neutron diffraction and Raman spectroscopy, shown with a sample of lead sulfate under ambient conditions as a proof of principle. In order to fulfil requirements of both methods, a sapphire single-crystal is used as a sample holder. Practical considerations for successful simultaneous in situ neutron diffraction and Raman spectroscopic measurements are given.

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Ciavarella, Susan, Graeme D. Batten y Anthony B. Blakeney. "Measuring Potassium in Plant Tissues Using near Infrared Spectroscopy". Journal of Near Infrared Spectroscopy 6, A (enero de 1998): A63—A66. http://dx.doi.org/10.1255/jnirs.167.

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Near infrared (NIR) spectroscopy is routinely used to determine constituents with organic bonds which absorb electromagnetic radiation in the region 1100 to 2500 nm. The nitrogen fertilizer requirements of cereal crops are determined from the analysis of vegetative samples by NIR spectroscopy. Simultaneous determination of other plant-essential elements would enhance the value of the analysis. Compared to nitrogen, other essential elements are either present at a lower concentration in the tissue or present largely in an inorganic form which is not detectable by NIR spectroscopy. In this paper we report NIR spectroscopic calibrations for potassium in grape petioles, grape leaves, rice shoots and orange leaves. When tested against a set of verification samples the NIR spectroscopic calibrations accounted for 96, 89, 93 and 85% of the concentration of K with standard errors of performance of 0.16, 0.12, 0.18 and 0.17%K respectively.

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Rameshan, Raffael, Andreas Nenning, Johannes Raschhofer, Lorenz Lindenthal, Thomas Ruh, Harald Summerer, Alexander Karl Opitz, Tobias Martin Huber y Christoph Rameshan. "Novel Sample-Stage for Combined Near Ambient Pressure X-ray Photoelectron Spectroscopy, Catalytic Characterization and Electrochemical Impedance Spectroscopy". Crystals 10, n.º 10 (17 de octubre de 2020): 947. http://dx.doi.org/10.3390/cryst10100947.

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For an in-depth characterization of catalytic materials and their properties, spectroscopic in-situ (operando) investigations are indispensable. With the rapid development of advanced commercial spectroscopic equipment, it is possible to combine complementary methods in a single system. This allows for simultaneously gaining insights into surface and bulk properties of functional oxides, such as defect chemistry, catalytic characteristics, electronic structure, etc., enabling a direct correlation of structure and reactivity of catalyst materials, thus facilitating effective catalyst development. Here, we present a novel sample-stage, which was specifically developed to pave the way to a lab–based combination of near ambient pressure X-ray photoelectron spectroscopy and electrochemical impedance spectroscopy with simultaneous catalytic operando measurements. This setup is designed to probe different (model) systems under conditions close to real heterogeneous catalysis, with a focus on solid oxide electrochemical cells. In a proof of concept experiment using an electrochemical model cell with the doped perovskite Nd0.6Ca0.4Fe0.9Co0.1O3-δ as working electrode, the precise control of the surface chemistry that is possible with this setup is demonstrated. The exsolution behavior of the material was studied, showing that at a lower temperature (500 °C) with lower reducing potential of the gas phase, only cobalt was exsolved, forming metallic particles on the surface of the perovskite-type oxide. Only when the temperature was increased to 600 °C and a cathodic potential was applied (−250 mV) Fe also started to be released from the perovskite lattice.

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Tarach, Karolina A., Anna K. Walczyk, Agata Kordek, Oliwia Rogala y Kinga Góra-Marek. "Silver-Loaded Chabazite in Ethanol-to-Hydrocarbon Process—Operando FT-IR and UV-Vis Spectroscopic Studies". Molecules 29, n.º 6 (8 de marzo de 2024): 1207. http://dx.doi.org/10.3390/molecules29061207.

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The ethanol dehydration process is studied regarding protonic and Ag-loaded chabazite zeolite in advanced FT-IR and UV-vis operando spectroscopic studies with simultaneous mass spectroscopy and gas chromatography analyses of products. The spectroscopic investigation provides information on the species formed on the surface of catalysts, while mass spectrometry and gas chromatography methods identify the desorbed products. These studies are also supported by spectroscopic, chromatographic, and thermogravimetric analyses of coke species formed over the catalyst’s surface during ethanol conversion. The Ag-chabazite catalyst shows higher selectivity for ethylene and propylene; the slower formation of coke species; and, thus, a longer lifetime.

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Janot-Pacheco, Eduardo y Nelson Vani Leister. "Seismology of southern Be stars". Symposium - International Astronomical Union 162 (1994): 104–5. http://dx.doi.org/10.1017/s0074180900214630.

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We have started in 1990 a search for moving bumps in the HeI λ 667.8 nm of mainly southern, bright Be stars. The objects of our sample have been selected on the basis of photometric variability (Cuypers et al., 1989). High resolution (R≥ 30,000), high signal-to-noise ratio (S/R≥ 300) spectroscopic observations have been performed at the brazilian Laboratório Nacional de Astrofísica with a CCD camera attached to the coudé spectrograph of the 1.60 m telescope (e.g. Table I). Several hundred spectra have been taken during the last three years. Photometric observations simultaneous with spectroscopy were made on the same site in July 1992 with a two-channel photometer (Stromgren b filter) and a CCD camera (Johnson B filter) installed at two 0.60 m telescopes. The idea is try to disentangle the controversy between NRP and RM models with the help of simultaneous spectroscopy and photometry.

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Thyrhaug, Erling, Stefan Krause, Antonio Perri, Giulio Cerullo, Dario Polli, Tom Vosch y Jürgen Hauer. "Single-molecule excitation–emission spectroscopy". Proceedings of the National Academy of Sciences 116, n.º 10 (15 de febrero de 2019): 4064–69. http://dx.doi.org/10.1073/pnas.1808290116.

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Single-molecule spectroscopy (SMS) provides a detailed view of individual emitter properties and local environments without having to resort to ensemble averaging. While the last several decades have seen substantial refinement of SMS techniques, recording excitation spectra of single emitters still poses a significant challenge. Here we address this problem by demonstrating simultaneous collection of fluorescence emission and excitation spectra using a compact common-path interferometer and broadband excitation, which is implemented as an extension of a standard SMS microscope. We demonstrate the technique by simultaneously collecting room-temperature excitation and emission spectra of individual terrylene diimide molecules and donor–acceptor dyads embedded in polystyrene. We analyze the resulting spectral parameters in terms of optical lineshape theory to obtain detailed information on the interactions of the emitters with their nanoscopic environment. This analysis finally reveals that environmental fluctuations between the donor and acceptor in the dyads are not correlated.

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Hoffmann, U., F. Pfeifer, S. Okretic, N. Völkl, M. Zahedi y H. W. Siesler. "Rheo-Optical Fourier Transform Infrared and Raman Spectroscopy of Polymers". Applied Spectroscopy 47, n.º 9 (septiembre de 1993): 1531–39. http://dx.doi.org/10.1366/0003702934067333.

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This article is intended to review recent results of simultaneous mechanical and Fourier transform infrared spectroscopic—so-called rheo-optical—measurements for polymer deformation studies. The technique will also be discussed in terms of the application of Fourier transform near-infrared light-fiber and Raman spectroscopy. Specifically, data on the bidirectional drawing of poly(ethylene terephthalate) and the strain-induced conformational changes of poly(vinylidene fluoride) will be presented.

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Velinov, Nena, Milica Petrović, Miljana Radović Vučić, Miloš Kostić, Jelena Mitrović, Danijela Bojić y Aleksandar Bojić. "Characterization and application of wood-ZrO2 sorbent for simultaneous removal of chromium (III) and chromium (VI) from binary mixture". Nordic Pulp & Paper Research Journal 36, n.º 2 (6 de marzo de 2021): 373–85. http://dx.doi.org/10.1515/npprj-2020-0082.

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Abstract A new woodchips-ZrO2 biosorbent (W-ZrO2) was synthesized using wood residue material generated from the oak tree (Quercus robur) during furniture manufacturing. Biosorbent was tested for the simultaneous removal of both chromium (Cr) ions: Cr(III) and Cr(VI), in the binary component solution. Biosorbent characterization was performed by scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction analysis (XRD). To define optimal process parameters for simultaneous removal of both Cr species, effects of pH, temperature, sorbent dosage and Cr ions concentration on the sorption process were investigated. Sorption of Cr ions onto W-ZrO2 was highly pH-dependent. Optimal pH for simultaneous removal of both Cr(III) and Cr(VI) ions is 4.0 with removal efficiency over 99.5 % in both cases. Equilibrium experimental results are the best fitted by the Langmuir sorption isotherm model. The maximal sorption capacities of the biosorbent for simultaneous removal of Cr(III) and Cr(VI) ions in binary-component system are 16.18 and 83.52 mg g−1, respectively. The present study shows that using wood residue material to produce a low-cost sorbent can effectively decrease the water pollution simultaneously removing both chromium species from water and also reduce wood waste and increase reuse/recycling options.

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Arévalo, Laura A., Stephen A. O’Brien, Eneko Lopez, Gajendra Pratap Singh y Andreas Seifert. "Design and Development of a Bimodal Optical Instrument for Simultaneous Vibrational Spectroscopy Measurements". International Journal of Molecular Sciences 23, n.º 12 (20 de junio de 2022): 6834. http://dx.doi.org/10.3390/ijms23126834.

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Vibrational spectroscopy techniques are widely used in analytical chemistry, physics and biology. The most prominent techniques are Raman and Fourier-transform infrared spectroscopy (FTIR). Combining both techniques delivers complementary information of the test sample. We present the design, construction, and calibration of a novel bimodal spectroscopy system featuring both Raman and infrared measurements simultaneously on the same sample without mutual interference. The optomechanical design provides a modular flexible system for solid and liquid samples and different configurations for Raman. As a novel feature, the Raman module can be operated off-axis for optical sectioning. The calibrated system demonstrates high sensitivity, precision, and resolution for simultaneous operation of both techniques and shows excellent calibration curves with coefficients of determination greater than 0.96. We demonstrate the ability to simultaneously measure Raman and infrared spectra of complex biological material using bovine serum albumin. The performance competes with commercial systems; moreover, it presents the additional advantage of simultaneously operating Raman and infrared techniques. To the best of our knowledge, it is the first demonstration of a combined Raman-infrared system that can analyze the same sample volume and obtain optically sectioned Raman signals. Additionally, quantitative comparison of confocality of backscattering micro-Raman and off-axis Raman was performed for the first time.

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26

Culaba, I. B., J. T. Maquiling y R. M. delos Santos. "Fabrication and applications of a novel and multi-feature spectroscope". Journal of Physics: Conference Series 2611, n.º 1 (1 de octubre de 2023): 012012. http://dx.doi.org/10.1088/1742-6596/2611/1/012012.

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Abstract A spectroscope is an optical device that can stimulate student’s interest in the visible light’s constituent colors. This educational tool is conventionally used to qualitatively observe the emission spectra of various light sources, which can serve as a springboard to understanding the fundamentals of spectroscopy, the wave nature of light, and the orbital theory of atoms and molecules. This research builds on the functionality and accessibility of a simple spectroscope through the utilization of low-cost readily available materials, and more importantly, improvisation via the inclusion of a magnetic sheet mounted on the entrance slit cover. The magnetic sheet was employed to vary the slit width, to add absorption filters, and to mount a cuvette containing liquid samples. Furthermore, this sheet allowed the simultaneous observation of the emission spectrum of a light source and the transmission or absorption spectrum of the samples. The breadth of data from a variety of activities involving spectra was also made possible by a mobile phone camera as a recording device. In this study, the novel features strengthen the interconnectedness of various concepts in introductory spectroscopy. This elucidates the experimental and theoretical base of STEM Education in domains such as optics and photonics, and molecular spectroscopy.

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27

Domes, Christian, Timea Frosch, Juergen Popp y Torsten Frosch. "Rapid Raman Spectroscopic Analysis of Stress Induced Degradation of the Pharmaceutical Drug Tetracycline". Molecules 25, n.º 8 (17 de abril de 2020): 1866. http://dx.doi.org/10.3390/molecules25081866.

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Stress factors caused by inadequate storage can induce the unwanted degradation of active compounds in pharmaceutical formulations. Resonance Raman spectroscopy is presented as an analytical tool for rapid monitoring of small concentration changes of tetracycline and the metabolite 4˗epianhydrotetracycline. These degradation processes were experimentally induced by changes in temperature, humidity, and irradiation with visible light over a time period of up to 23 days. The excitation wavelength λexc = 413 nm was proven to provide short acquisition times for the simultaneous Raman spectroscopic detection of the degradation of tetracycline and production of its impurity in small sample volumes. Small concentration changes could be detected (down to 1.4% for tetracycline and 0.3% for 4-epianhydrotetracycline), which shows the potential of resonance Raman spectroscopy for analyzing the decomposition of pharmaceutical products.

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28

Lewis, E. N., L. H. Kidder y I. W. Levin. "High Spatial and High Spectral Resolution FTIR Spectroscopic Imaging of Biological Materials". Microscopy and Microanalysis 3, S2 (agosto de 1997): 831–32. http://dx.doi.org/10.1017/s1431927600011041.

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Infrared spectroscopy has been used to probe a variety of biological systems including for example, the determination of diseased states and the investigation of foreign inclusions in biologicals. The technique generates qualitative and quantitative information on the structure and dynamics of samples, including lipids, proteins, and non-biological constituents. The coupling of imaging modalities with spectroscopic techniques adds a new dimension to sample analysis in both the spectroscopic and spatial domains. Using a spectroscopic imaging system that incorporates a step-scan interferometer, microscope, and infrared sensitive arrays, we have investigated a variety of biological samples. This seamless combination of spectroscopy for molecular analysis with the power of visualization generates chemically specific images while simultaneously obtaining high resolution spectra for each detector pixel. The spatial resolution of the images approaches the diffraction limit for mid-infrared wavelengths, while the spectral resolution is determined by the interferometer and can be 4 cm−1 or higher.

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Neil Lewis, E., Abigail S. Haka, Pina Colarusso, Ira W. Levin, John Gillespie y Linda H. Kidder. "Evaluation Of Diseased State In Human Tissue Sections Using Infrared And Raman Imaging Microspectroscopy". Microscopy and Microanalysis 5, S2 (agosto de 1999): 60–61. http://dx.doi.org/10.1017/s1431927600013623.

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Optical microscopy has been the workhorse pathological technique, qualitatively differentiating tissue sections by characterizing morphological variations. Vibrational spectroscopic techniques provide quantitative as well as qualitative analytical information that reflects a sample’s biochemical composition and molecular structure. The utility of infrared and Raman techniques for biological characterization has been demonstrated for a variety of applications.[1-4]FTIR imaging microscopy is a newly developed technique that incorporates the imaging capabilities required for histological procedures with the chemical discrimination of IR spectroscopy.[5-7] The ability to maintain spatial integrity while accessing precise spectroscopic data intrinsic to the sample represents a powerful combination. This technique is much more amenable to analysis by a pathologist than conventional spectroscopy because the data can be presented as images. These images provide direct visualization of a sample’s biochemical heterogeneity.Vibrational spectroscopic imaging techniques provide excellent sample statistics for the accurate classification of individual spectral signatures because tens of thousands of independent spectra from different spatial locations within the sample are simultaneously recorded.

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30

Delli Santi, Maria Giulia, Salvatore Castrignano, Marialuisa Capezzuto, Marco Consales, Patrizio Vaiano, Andrea Cusano, Gianluca Gagliardi y Pietro Malara. "Optrode-Assisted Multiparametric Near-Infrared Spectroscopy for the Analysis of Liquids". Sensors 24, n.º 3 (23 de enero de 2024): 729. http://dx.doi.org/10.3390/s24030729.

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We demonstrate a sensing scheme for liquid analytes that integrates multiple optical fiber sensors in a near-infrared spectrometer. With a simple optofluidic method, a broadband radiation is encoded in a time-domain interferogram and distributed to different sensing units that interrogate the sample simultaneously; the spectral readout of each unit is extracted from its output signal by a Fourier transform routine. The proposed method allows performing a multiparametric analysis of liquid samples in a compact setup where the radiation source, measurement units, and spectral readout are all integrated in a robust telecom optical fiber. An experimental validation is provided by combining a plasmonic nanostructured fiber probe and a transmission cuvette in the setup and demonstrating the simultaneous measurement of the absorption spectrum and the refractive index of water–methanol solutions.

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31

Mehta, Pratik S., Pratik R. Patel, Rajesh R. Parmar, M. M. K. Modasiya y Dushyant A. Shah. "Development and Validation of Derivative Spectroscopic Method for Simultaneous Estimation of Cefadroxil and Probenecid". International Journal of Pharmaceutical Sciences and Nanotechnology 7, n.º 1 (28 de febrero de 2014): 2350–55. http://dx.doi.org/10.37285/ijpsn.2014.7.1.6.

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A novel, simple, accurate, sensitive, precise and economical derivative spectroscopic method was developed and validated for the determination of cefadroxil and probenecid in synthetic mixture. First order derivative spectroscopy method was adopted to eliminate spectral interference. The method obeys Beer’s Law in concentration ranges of 4-36 μg/ml for cefadroxil and of 5-25 μg/ml of probenecid. The zero crossing point for cefadroxil and probenecid was 260 nm and 237.8 nm respectively in 0.1N HCl. The method was validated in terms of accuracy, precision, linearity, limits of detection, limits of quantitation. This method has been successively applied to synthetic mixture and no interference from the synthetic mixture’s excipients was found.

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32

Pelletier, Isabelle, Christian Pellerin, D. Bruce Chase y John F. Rabolt. "New Developments in Planar Array Infrared Spectroscopy". Applied Spectroscopy 59, n.º 2 (febrero 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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33

Winterauer, Dominik J., Daniel Funes-Hernando, Jean-Luc Duvail, Saïd Moussaoui, Tim Batten y Bernard Humbert. "Nanoscale Spatial Resolution in Far-Field Raman Imaging Using Hyperspectral Unmixing in Combination with Positivity Constrained Super-Resolution". Applied Spectroscopy 74, n.º 7 (26 de mayo de 2020): 780–90. http://dx.doi.org/10.1177/0003702820920688.

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This work introduces hyper-resolution (HyRes), a numerical approach for spatial resolution enhancement that combines hyperspectral unmixing and super-resolution image restoration (SRIR). HyRes yields a substantial increase in spatial resolution of Raman spectroscopy while simultaneously preserving the undistorted spectral information. The resolving power of this technique is demonstrated on Raman spectroscopic data from a polymer nanowire sample. Here, we demonstrate an achieved resolution of better than 14 nm, a more than eightfold improvement on single-channel image-based SRIR and [Formula: see text] better than regular far-field Raman spectroscopy, and comparable to near-field probing techniques.

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34

Harju, Mauno E. E. "Solid-State Transition Mechanisms of Ammonium Nitrate Phases IV, III, and II Investigated by Simultaneous Raman Spectrometry and Differential Scanning Calorimetry". Applied Spectroscopy 47, n.º 11 (noviembre de 1993): 1926–30. http://dx.doi.org/10.1366/0003702934066127.

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The solid-state transition mechanisms of ammonium nitrate IV, III, and II were studied by measuring samples simultaneously by Raman spectrometry and differential scanning calorimetry (DSC). The Raman instruments were a Fourier transform Raman spectrophotometer and triple monochromator Raman spectrophotometer with charge-coupled-device (CCD) detector. The spectral data of the transitions were collected simultaneously with the calorimetric data in the temperature-scanning mode of the calorimeter and then isothermally between transitions. The phase transition from phase IV to phase III occurred through an intermediate phase II*, whose lifetime was seven minutes maximum when the onset temperature of the reaction was close to the phase-transition IV → II onset temperature. It is concluded that there is always an intermediate phase II* between IV and III. Simultaneous Raman measurements are shown to be an effective tool for interpreting complex DSC curves.

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35

Gies, D. R. y David McDavid. "Simultaneous Spectroscopy and Polarimetry of Be Stars". International Astronomical Union Colloquium 92 (agosto de 1987): 84–86. http://dx.doi.org/10.1017/s0252921100116069.

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Evidence is now accumulating that many Be stars display photospheric line profile variations on timescales of days or less that are probably caused by nonradial pulsations (Baade 1984; Penrod 1986). In some circumstances these pulsations can promote mass loss into the circumstellar envelope, and consequently the conditions in the inner part of the envelope may vary on similar timescales. Changes in the envelope could produce variations in the polarization and emission line profiles, and observers have reported rapid variability in both. We describe here an initial attempt to search for simultaneous variations in continuum polarization, Hα emission, and the He I λ6678 photospheric absorption line in order to investigate correlated changes on short timescales.

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36

Brangule, Agnese, Kārlis Gross, Ingus Skadiņš, Aigars Reinis y Juta Kroiča. "Simultaneous Identification of Amorphous Calcium Phosphate and S.epidermidis Bacteria by Photoacoustic Spectroscopy". Key Engineering Materials 720 (noviembre de 2016): 125–29. http://dx.doi.org/10.4028/www.scientific.net/kem.720.125.

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The incorporation of biomaterials in human tissue requires methods to study the interface of the implant with the biological setting. We set out to study whether Photoacoustic spectroscopy with a higher level of sensitivity from the cantilever detector could simultaneously detect amorphous calcium phosphate and the bacteria. The calcium phosphate was synthesized, pressed into tablets, and then immersed in a solution containing S.epidermidis bacteria. Spectra were recorded after 1, 2, 3, 4 and 5 days. Deconvolution of the spectra at different time periods was able to separate bands belonging to the bacteria and carbonate bands arising from the calcium phosphate. This allowed the simultaneous identification of the biomaterial and bacteria. It was found that the PAS spectra could not identify the bacterial adhesion process due to the low concentration, but the amide peaks at 3 days inferred colonization of bacteria. This was confirmed by SEM that shoed an increase in the bacteria concentration. This is the first step in showing the simultaneous detection of calcium phosphate and bacteria by Photoacoustic spectroscopy, a method that required more research to show changes on the surface of the implant.

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37

Franko, Mladen y Chieu D. Tran. "Simultaneous Determination of Two-Component Mixtures and pHs by Dual-Wavelength Thermal Lens Spectrometry". Applied Spectroscopy 43, n.º 4 (mayo de 1989): 661–68. http://dx.doi.org/10.1366/0003702894202463.

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The recently developed dual-wavelength thermal lens spectrometer, which is capable of simultaneously measuring thermal lens signals at two different wavelengths, has been used to simultaneously determine two-component samples and solution pHs. Compared to conventional absorption spectrophotometry, this dual-wavelength technique offers advantages that include fast data acquisition and higher sensitivity. With the use of 20-mW excitation beams, the limits of detection for the simultaneous determination of ferroin and iron(II) bipyridyl complexes mixtures are estimated to be 3.6 × 10−9 M and 8.4 × 10−9 M, respectively. In addition, the high monochromaticity of the laser makes this technique uniquely suited for the simultaneous determination of two-component samples whose absorption bandwidths are too narrow to be determined by the conventional spectrophotometric method. The limits of detection for the Er3+ and Nd3+ ions in the two-component mixtures are estimated to be 8.9 × 10−4 M and 7.6 × 10−5 M, respectively. Solution pHs have also been sensitively and accurately determined by using this technique to measure the concentrations of the protonated and deprotonated forms of an indicator. Similar to the two-component sample determination, this thermal lens technique is superior to the conventional spectrophotometric method because it is fast, has relatively higher sensitivity, and allows an indicator to be used over a wider pH range. Solution pHs, ranging from 2 to 9, have been determined accurately with this technique, with the use of such indicators as phenol red, methyl orange, and thymol blue, whose concentrations can be as low as 10−9 M.

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38

M. Patel, Shivani y Lalit L. Jha. "SIMULTANEOUS UV METHOD DEVELOPMENT FOR DETERMINATION OF ROTIGOTINE HYDROCHLORIDE AND RASAGILINE MESYLATE". Indian Drugs 60, n.º 05 (28 de mayo de 2023): 73–79. http://dx.doi.org/10.53879/id.60.05.13373.

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A precise, accurate analytical UV spectroscopic method has been developed for simultaneous estimation of rotigotine hydrochloride and rasagiline mesylate by using first order derivative spectroscopy. 50 µg mL-1 solutions of both drugs were scanned in the range of 200-800 nm and the first order overlain spectra of both drugs to check zero crossing points. Rotigotine hydrochloride showed zero crossing point at 239 nm where and rasagiline mesylate showed at 273 nm. Six-point calibration curves shown linearity in 2-12 µg mL-1 concentration range for rotigotine hydrochloride and 10-60 µg mL-1 concentration range for rasagiline mesylate. Regression equation obtained for both drugs were used further for determination of concentration in accuracy studies and developed product. In bulk drugs, rasagiline mesylate showed recovery of 98.33-100.93 % and rotigotine hydrochloride showed recovery of 101-103 %. The results obtained from analysis were validated according to ICH guidelines and were found at up to the mark.

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39

Drabik, Jolanta, Rafał Kozdrach y Edyta Osuch-Słomka. "EFFECT OF THE BIO-LUBRICANT ON THE LUBRICATINGPROPERTIES AND SURFACE OF THE FRICTION ZONE". Tribologia 306, n.º 4 (29 de febrero de 2024): 7–13. http://dx.doi.org/10.5604/01.3001.0054.3931.

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Tests carried out on a rotational rheometer with a tribological cell enabled the simultaneous designation oflubricating and viscosity characteristics depending on temperature and load as a function of variable slidingspeed. The analysis of the dependence of the coefficient of friction on the sliding speed provided the basis forevaluating the effectiveness of lubrication of steel tribosystems with bio-lubricants. Spectroscopic methodswere used to monitor changes in the microstructure of the bio-lubricants after tests. The scanning electronmicroscopy (SEM) and energy dispersive spectroscopy (EDS) were used to characterise the morphologyand structure of the surfaces of the tribosystem elements. The instrumental methods used confirmed that thetest conditions did not destabilise the chemical structure of the lubricant and did not accelerate the oxidationprocess of the vegetable grease.

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40

Lafouresse, M. C., U. Bertocci, C. R. Beauchamp y G. R. Stafford. "Simultaneous Electrochemical and Mechanical Impedance Spectroscopy Using Cantilever Curvature". Journal of The Electrochemical Society 159, n.º 10 (2012): H816—H822. http://dx.doi.org/10.1149/2.055210jes.

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41

Wei, Qianhe, Bincheng Li, Jing Wang, Binxing Zhao y Ping Yang. "Impact of Residual Water Vapor on the Simultaneous Measurements of Trace CH4 and N2O in Air with Cavity Ring-Down Spectroscopy". Atmosphere 12, n.º 2 (6 de febrero de 2021): 221. http://dx.doi.org/10.3390/atmos12020221.

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Methane (CH4) and nitrous oxide (N2O) are among the most important atmospheric greenhouse gases. A gas sensor based on a tunable 7.6 μm continuous-wave external-cavity mode-hop-free (EC-MHF) quantum cascade laser (from 1290 to 1350 cm−1) cavity ring-down spectroscopy (CRDS) technique was developed for the simultaneous detection of CH4 and N2O in ambient air with water vapor (H2O) mostly removed via molecular sieve drying to minimize the impact of H2O on the simultaneous measurements. Still, due to the broad and strong absorption spectrum of H2O in the entire mid-infrared (mid-IR) spectral range, residual H2O in the dried ambient air due to incomplete drying and leakage, if not properly accounted for, could cause a significant influence on the measurement accuracy of the simultaneous CH4 and N2O detection. In this paper, the impact of residual H2O on the simultaneous CH4 and N2O measurements were analyzed by comparing the CH4 and N2O concentrations determined from the measured spectrum in the spectral range from 1311 to 1312.1 cm−1 via simultaneous CH4 and N2O measurements and that determined from the measured spectrum in the spectral range from 1311 to 1313 cm−1 via simultaneous CH4, N2O, and H2O measurements. The measured dependence of CH4 and N2O concentration errors on the simultaneously determined H2O concentration indicated that the residual H2O caused an under-estimation of CH4 concentration and over-estimation of N2O concentration. The H2O induced CH4 and N2O concentration errors were approximately linearly proportional to the residual H2O concentration. For the measurement of air flowing at 3 L per min, the residual H2O concentration was stabilized to approximately 14 ppmv, and the corresponding H2O induced errors were −1.3 ppbv for CH4 and 3.7 ppbv for N2O, respectively.

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42

Krstić, Marko y Slavica Ražić. "Analytical Approaches to the Characterization of Solid Drug Delivery Systems with Porous Adsorbent Carriers". Current Medicinal Chemistry 25, n.º 33 (24 de octubre de 2018): 3956–72. http://dx.doi.org/10.2174/0929867325666180212120908.

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A large variety of analytical techniques are available to meet the needs of characterization of solid samples. But, when solid drug delivery systems are concerned we are faced with demanding methodologies which have to compile capabilities of analytical techniques in regard to large diversity of structures and surface functionality of analyzed adsorbent carriers. In this review, the most commonly used analytical techniques are presented with their basic principles, advantages and disadvantages in applications of interest. Adsorbent carriers are widely used today as ingredients in the formulation of pharmaceutical forms, for increasing the dissolution rate of the drug and hence the bioavailability. They are also used in the formulation of substances with modified or target drug release into a specific tissue. Methods of thermal analysis (Thermogravimetry - TGA, Differential Scanning Calorimetry - DSC and Thermal microscopy - TM), spectroscopic methods (Infrared Spectroscopy - IR, especially Fourier Transform Infrared Spectroscopy - FTIR and Raman spectroscopy), crystallographic methods (Powder X-Ray Diffraction - PXRD) and finally Scanning Electron Microscopy (SEM) are the most powerful in the characterization of modern therapeutic systems with porous adsorbents. The problem-solving power of each particular analytical method is often enhanced by using simultaneous methods rather than a single technique.

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43

Islam, Kamrunnahar, Balwant Singh y Alex McBratney. "Simultaneous estimation of several soil properties by ultra-violet, visible, and near-infrared reflectance spectroscopy". Soil Research 41, n.º 6 (2003): 1101. http://dx.doi.org/10.1071/sr02137.

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Fast and convenient soil analytical techniques are needed for soil quality assessment and precision soil management. Spectroscopy in the ultraviolet (UV, 250–400 nm), visible (VIS, 400–700 nm), and near-infrared (NIR, 700–2500 nm) ranges allows rapid acquisition of soil information at quantitative, and qualitative or indicator, levels for use in agriculture and environmental monitoring. The main objective of this study was to evaluate the ability of reflectance spectroscopy in the UV, VIS, and NIR ranges to predict several soil properties simultaneously. Soil samples (161 surface and subsurface) were used for simultaneous estimation of pH, electrical conductivity (EC), air-dry gravimetric water content, organic carbon (OC), free iron, clay, sand, and silt contents, cation exchange capacity (CEC), and exchangeable calcium (Ca), magnesium (Mg), potassium (K), and sodium (Na). Principal component regression analyses (PCA) were used to develop calibration equations between the reflectance spectral data and measured values for the above soil properties obtained by traditional laboratory methods. By using randomly selected calibration and validation sets of samples, PCA models were able to successfully predict pH, OC, air-dry gravimetric water content, clay, CEC, exchangeable Ca, and exchangeable Mg of soil samples. The predictions, however, were poor for EC, free iron, sand, silt, exchangeable K, and exchangeable Na. The study shows that reflectance spectroscopy in the UV–VIS–NIR range has the potential for the rapid simultaneous prediction of several soil properties.

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Guo, Lan-Ping, Jian Yang, Li Zhou, Sheng Wang, Chuan-Zhi Kang y Christian W. Huck. "Simultaneous Quantification of 14 Compounds in Achillea millefolium by GC-MS Analysis and Near-Infrared Spectroscopy Combined with Multivariate Techniques". Journal of Analytical Methods in Chemistry 2021 (24 de mayo de 2021): 1–10. http://dx.doi.org/10.1155/2021/5566612.

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The proposed work is focused on the simultaneous quantification of 14 compounds in the medicinal plant Achillea millefolium based on Near-Infrared Spectroscopy (NIR). The regression model of single-compound models (SCMs) and multicompound model (MCM) were created by partial least-squares regression (PLSR). Also, these models were calibrated by gas chromatographic mass spectroscopy (GC-MS). The results showed that the averaged standard errors of prediction (SEP) for the SCMs and MCM were 0.49 and 0.62, respectively, and most of the 14 compounds were significantly correlated. 43 correlations were significant at the 0.01 level (47.25% of the total), and 11 correlations were significant at the 0.05 level (12.09% of the total). The first three principal components (PCs) of principal component analysis (PCA) can explain >78% of the total variance. According to the component matrix and the communality table, octadecanoic acid has the largest influence on PC 1 (extraction squared = 46.72%), whose extraction was 0.932. The communality of neophytadiene, Z,Z,Z-9,12,15-octadecatrienoic acid, and oleic acid was also found to be large, whose extractions were 0.955, 0.937, and 0.859, respectively. These results indicate that if one compound shows a linear relationship with the NIR absorbance signal (SCM) also, an MCM can be created due to the close interrelations of these compounds. In this context, the present work highlights a suitable sample preparation technique to perform NIR analysis of raw plant material to benefit from robust and precise calibrations. To sum up, this NIR spectroscopic approach offers a precise, rapid, and cost-effective high-throughput analytical technique to simultaneously and noninvasively perform quantitative analysis of raw plant materials.

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45

Tzeng, W. B., K. Narayanan y G. C. Chang. "Simultaneous Detection of C6H5NHD, C6H5ND2, C6D5NH2, C6D5NHD, and C6D5ND2 by Resonant Two-Photon Ionization Mass Spectrometry". Applied Spectroscopy 52, n.º 6 (junio de 1998): 890–93. http://dx.doi.org/10.1366/0003702981944445.

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The resonant two-photon ionization (R2PI) spectra of jet-cooled C6H5NH2, C6H5NHD, C6H5ND2, C6D5NH2, C6D5NHD, and C6D5ND2 resulting from the S1← S0 electronic transition have been simultaneously recorded in three different sample mixtures. New data on C6H5NHD and C6D5NHD are presented for the first time. The observed R2PI spectral bands of these species are successfully assigned on the basis of observed frequency shifts in some vibrational modes of deuterated species and calculated ab initio values. On the basis of mass separation and optical spectral analyses, this method provides an unambiguous means for the simultaneous and selective detection of isotopically substituted anilines presented in the mixture.

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46

Zhu, Jianxiong, Charles K. Mann y Thomas J. Vickers. "Simultaneous Dual-Window Measurements with a Linear Photodiode Array Detector". Applied Spectroscopy 42, n.º 8 (noviembre de 1988): 1567–71. http://dx.doi.org/10.1366/0003702884429733.

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A generally applicable method is described for simultaneous measurement of reference and analyte spectral features which would not otherwise fall within the range covered by a single linear diode array detector. The method employs dual entrance slits on the spectrometer to cause two spectral windows to overlap on the detector. The method is demonstrated for fluorescence measurement of Rhodamine B in ethanol. Recovery of the spectral information from the overlapped spectra using a least-squares fitting procedure is demonstrated. The simultaneously recorded reference measurements are shown to be effective in correcting for excitation source intensity variation by comparing corrected and uncorrected excitation spectra and calibration curve data.

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47

El-Zohry, Ahmed M. y E. Y. Hashem. "Environmental Method to Determine Dopamine and Ascorbic Acid Simultaneously via Derivative Spectrophotometry". Journal of Spectroscopy 2013 (2013): 1–7. http://dx.doi.org/10.1155/2013/260376.

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Many various methods were applied to determine dopamine and ascorbic acid simultaneously using hazardous materials and complex procedures. Derivative absorption spectra can give safely and five sensitive derivative equations that are used for the simultaneous determination of dopamine and ascorbic acid in the UV region, using first and second derivative spectroscopy with high precision at pH value of 9.2. Dopamine and ascorbic acid can be detected in the ranges of 0.375–9.45 mg L−1and 0.352–5.28 mg L−1, respectively. These obtained methods could be used to determine both reagents in real and synthesized samples.

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Peng, Zhimin, Yanjun Du y Yanjun Ding. "Highly Sensitive, Calibration-Free WM-DAS Method for Recovering Absorbance—Part I: Theoretical Analysis". Sensors 20, n.º 3 (26 de enero de 2020): 681. http://dx.doi.org/10.3390/s20030681.

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The absorbance is of great importance in the tunable diode laser absorption spectroscopy (TDLAS) as it contains information of both gas properties and spectroscopic parameters. A novel, calibration-free wavelength modulation-direct absorption spectroscopy (WM-DAS) is proposed and experimentally verified in this two-part paper. This method combines the capability of absorbance measurement from DAS and the advantages of enhanced noise rejection and high sensitivity from WMS. In this Part I, we focus on the full theoretical basis and procedures of this method from the following three aspects: the high-accuracy characterizations of laser frequency and intensity, noise rejection ability by extracting the characteristic spectra through the fast Fourier transform (FFT) of the light intensity, and the simultaneous fitting strategy for both baseline and absorbance. The preliminary validation experiment of CO transition at 4300.6999 cm−1 in a static gas cell shows the high accuracy of the proposed method.

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Osmakov, I. A., T. A. Savelieva, V. B. Loschenov, S. A. Goryajnov y A. A. Potapov. "Cluster analysis of the results of intraoperative optical spectroscopic diagnostics In brain glioma neurosurgery". Biomedical Photonics 7, n.º 4 (14 de enero de 2019): 23–34. http://dx.doi.org/10.24931/2413-9432-2018-7-4-23-34.

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The paper presents the results of a comparative study of methods of cluster analysis of optical intraoperative spectroscopy data during surgery of glial tumors with varying degree of malignancy. The analysis was carried out both for individual patients and for the entire dataset. The data were obtained using combined optical spectroscopy technique, which allowed simultaneous registration of diﬀuse reﬂectance spectra of broadband radiation in the 500–600 nm spectral range (for the analysis of tissue blood supply and the degree of hemoglobin oxygenation), ﬂuorescence spectra of 5‑ALA induced protoporphyrin IX (Pp IX) (for analysis of the malignancy degree) and signal of diffusely reﬂected laser light used to excite Pp IX ﬂuorescence (to take into account the scattering properties of tissues). To determine the threshold values of these parameters for the tumor, the infltration zone and the normal white matter, we searched for the natural clusters in the available intraoperative optical spectroscopy data and compared them with the results of the pathomorphology. It was shown that, among the considered clustering methods, EM‑algorithm and k‑means methods are optimal for the considered data set and can be used to build a decision support system (DSS) for spectroscopic intraoperative navigation in neurosurgery. Results of clustering relevant to thepathological studies were also obtained using the methods of spectral and agglomerative clustering. These methods can be used to postprocess combined spectroscopy data.

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Liu, Ning, Timothy Y. Chen, Hongtao Zhong, Ying Lin, Ziyu Wang y Yiguang Ju. "Femtosecond ultraviolet laser absorption spectroscopy for simultaneous measurements of temperature and OH concentration". Applied Physics Letters 120, n.º 20 (16 de mayo de 2022): 201103. http://dx.doi.org/10.1063/5.0091572.

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This Letter reports a femtosecond ultraviolet laser absorption spectroscopy (fs-UV-LAS) for simultaneous in situ measurements of temperature and species. This fs-UV-LAS technique was demonstrated based on X2Π-A2Σ+ transitions of OH radicals near 308 nm generated in low temperature plasmas and flames. The fs-UV-LAS technique has revealed three major diagnostic benefits. First, a series of absorption features within a spectral bandwidth of ∼3.2 nm near 308 nm were simultaneously measured and then enabled simultaneous multi-parameter measurements with enhanced accuracy. The results show that the temperature and OH concentration could be measured with accuracy enhanced by 29–88% and 58–91%, respectively, compared to those obtained with past two-narrow-line absorption methods. Second, an ultrafast time resolution of ∼120 picoseconds was accomplished for the measurements. Third, due to the large OH X2Π-A2Σ+ transitions in the UV range, a simple single-pass absorption with a 3-cm path length was allowed for measurements in plasmas with low OH number density down to ∼2 × 1013 cm−3. Also due to the large OH UV transitions, single-shot fs absorption measurements were accomplished in flames, which was expected to offer more insights into chemically reactive flow dynamics.

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