WorldWideScience

Sample records for terahertz reflection spectroscopy

  1. Terahertz time-domain transmission and reflection spectroscopy of niobium

    International Nuclear Information System (INIS)

    Hong, Tae Yoon; Choi, Kyu Jin; Park, Byoung Cheol; Ha, Tae Woo; Sim, Kyung Ik; Kim, Jea Hoon; Ha, Dong Gwang; Chang, Yonuk

    2013-01-01

    We have developed a terahertz time-domain spectroscopy (THz-TDS) system for transmission and reflection measurements of metallic thin films. Using our THz-TDS system, we studied the conventional superconductor niobium (Nb) in the normal state in the spectral range from 5 to 50 cm -1 . Both the real and imaginary parts of the conductivity are acquired without Kramers-Kronig analysis. Nb exhibits a nearly frequency independent real conductivity spectrum in the terahertz range, with a very small imaginary part.

  2. Quality assessment of terahertz time-domain spectroscopy transmission and reflection modes for graphene conductivity mapping

    DEFF Research Database (Denmark)

    Mackenzie, David M.A.; Whelan, Patrick Rebsdorf; Bøggild, Peter

    2018-01-01

    We present a comparative study of electrical measurements of graphene using terahertz time-domain spectroscopy in transmission and reflection mode, and compare the measured sheet conductivity values to electrical van der Pauw measurements made independently in three different laboratories. Overall......, while offering the additional advantages associated with contactless mapping, such as high throughput, no lithography requirement, and with the spatial mapping directly revealing the presence of any inhomogeneities or isolating defects. The confirmation of the accuracy of reflection-mode removes...

  3. Terahertz reflection spectroscopy of Debye relaxation in polar liquids

    DEFF Research Database (Denmark)

    Møller, Uffe; Cooke, David; Tanaka, Koichiro

    2009-01-01

    Terahertz (THz) radiation interacts strongly with the intermolecular hydrogen-bond network in aqueous liquids. The dielectric properties of liquid water and aqueous solutions in the THz spectral region are closely linked to the microscopic dynamics of the liquid solution, and hence THz spectrosco...

  4. Terahertz spectroscopy

    DEFF Research Database (Denmark)

    Jepsen, Peter Uhd

    2009-01-01

    In this presentation I will review methods for spectroscopy in the THz range, with special emphasis on the practical implementation of the technique known ad THz time-domain spectroscopy (THz-TDS). THz-TDS has revived the old field of far-infrared spectroscopy, and enabled a wealth of new...... activities that promise commercial potential for spectroscopic applications in the THz range. This will be illustrated with examples of spectroscopy of liquids inside their bottles as well as sensitive, quantitative spectroscopy in waveguides....

  5. Terahertz Spectroscopy and Imaging

    CERN Document Server

    Zeitler, Axel; Kuwata-Gonokami, Makoto

    2013-01-01

    "This book presents the current state of knowledge in the field of terahertz spectroscopy, providing a comprehensive source of information for beginners and experienced researchers alike whose interests lie in this area. The book aims to explain the fundamental physics that underpins terahertz  technology and to describe its key applications. Highlights of scientific research in the field of terahertz science are also outlined in some chapters, providing an overview as well as giving an insight into future directions for research.  Over the past decade terahertz spectroscopy has developed into one of the most rapidly growing areas of its kind, gaining an important impact across a wide range of scientific disciplines. Due to substantial advances in femtosecond laser technology, terahertz time-domain spectroscopy (THz-TDS) has established itself as the dominant spectroscopic technique for experimental scientists interested in measurements at this frequency range. In solids and liquids THz radiation is in reso...

  6. Terahertz time-domain attenuated total reflection spectroscopy applied to the rapid discrimination of the botanical origin of honeys

    Science.gov (United States)

    Liu, Wen; Zhang, Yuying; Yang, Si; Han, Donghai

    2018-05-01

    A new technique to identify the floral resources of honeys is demanded. Terahertz time-domain attenuated total reflection spectroscopy combined with chemometrics methods was applied to discriminate different categorizes (Medlar honey, Vitex honey, and Acacia honey). Principal component analysis (PCA), cluster analysis (CA) and partial least squares-discriminant analysis (PLS-DA) have been used to find information of the botanical origins of honeys. Spectral range also was discussed to increase the precision of PLS-DA model. The accuracy of 88.46% for validation set was obtained, using PLS-DA model in 0.5-1.5 THz. This work indicated terahertz time-domain attenuated total reflection spectroscopy was an available approach to evaluate the quality of honey rapidly.

  7. Investigating murals with terahertz reflective tomography

    Science.gov (United States)

    Yuan, Minjie; Sun, Wenfeng; Wang, Xinke; Wang, Sen; Zhang, Qunxi; Ye, Jiasheng; Zhang, Yan

    2015-08-01

    Terahertz time-domain spectroscopy (THz-TDS) imaging technology has been proposed to be used in the non-invasive detection of murals. THz-TDS images provide structural data of the sample that cannot be obtained with other complementary techniques. In this paper, two types of defects hidden in the plaster used to simulate the cases of defects in the murals, have been investigated by the terahertz reflected time domain spectroscopy imaging system. These preset defects include a leaf slice and a slit built in the plaster. With the terahertz reflective tomography, information about defects has been determined involving the thickness from the surface of sample to the built-in defect, the profile and distribution of the defect. With this THz tomography, different defects with the changes of optical thickness and their relative refractive index have been identified. The application of reflective pulsed terahertz imaging has been extended to the defect detection of the murals.

  8. Characterizing the hydration state of L-threonine in solution using terahertz time-domain attenuated total reflection spectroscopy

    Science.gov (United States)

    Huang, Huachuan; Liu, Qiao; Zhu, Liguo; Li, Zeren

    2018-01-01

    The hydration of biomolecules is closely related to the dynamic process of their functional expression, therefore, characterizing hydration phenomena is a subject of keen interest. However, direct measurements on the global hydration state of biomolecules couldn't have been acquired using traditional techniques such as thermodynamics, ultrasound, microwave spectroscopy or viscosity, etc. In order to realize global hydration characterization of amino acid such as L-threonine, terahertz time-domain attenuated total reflectance spectroscopy (THz-TDS-ATR) was adopted in this paper. By measuring the complex permittivity of L-threonine solutions with various concentrations in the THz region, the hydration state and its concentration dependence were obtained, indicating that the number of hydrous water decreased with the increase of concentration. The hydration number was evaluated to be 17.8 when the molar concentration of L-threonine was 0.34 mol/L, and dropped to 13.2 when the molar concentration increased to 0.84 mol/L, when global hydration was taken into account. According to the proposed direct measurements, it is believed that the THz-TDS-ATR technique is a powerful tool for studying the picosecond molecular dynamics of amino acid solutions.

  9. Nanoscale Terahertz Emission Spectroscopy

    DEFF Research Database (Denmark)

    Pedersen, Pernille Klarskov; Kim, Hyewon; Colvin, Vicki L.

    By utilizing plasmonic coupling to an AFM probe, we demonstrate Laser Terahertz Emission Nanoscopy (LTEN) with sub-20 nm resolution. We demonstrate the resolution by imaging a single gold nanorod on an InAs substrate....

  10. Resonant metallic nanostructures for enhanced terahertz spectroscopy

    KAUST Repository

    Toma, A.

    2015-11-12

    We present our recent studies on terahertz resonant dipole nanoantennas. Exploiting the localization and enhancement capabilities of these devices, we introduce an effective method to perform terahertz spectroscopy on an extremely small number of nano-objects.

  11. Resonant metallic nanostructures for enhanced terahertz spectroscopy

    KAUST Repository

    Toma, A.; Tuccio, S.; Prato, M.; De Donato, F.; Perucchi, A.; Di Pietro, P.; Marras, S.; Liberale, Carlo; Zaccaria, R. Proietti; De Angelis, F.; Manna, L.; Lupi, S.; Di Fabrizio, Enzo M.; Razzari, L.

    2015-01-01

    We present our recent studies on terahertz resonant dipole nanoantennas. Exploiting the localization and enhancement capabilities of these devices, we introduce an effective method to perform terahertz spectroscopy on an extremely small number

  12. Toward practical terahertz time-domain spectroscopy

    Science.gov (United States)

    Brigada, David J.

    Terahertz time-domain spectroscopy is a promising technology for the identification of explosive and pharmaceutical substances in adverse conditions. It interacts strongly with intermolecular vibrational and rotational modes. Terahertz also passes through many common dielectric covering materials, allowing for the identification of substances in envelopes, wrapped in opaque plastic, or otherwise hidden. However, there are several challenges preventing the adoption of terahertz spectroscopy outside the laboratory. This dissertation examines the problems preventing widespread adoption of terahertz technology and attempts to resolve them. In order to use terahertz spectroscopy to identify substances, a spectrum measured of the target sample must be compared to the spectra of various known standard samples. This dissertation examines various methods that can be employed throughout the entire process of acquiring and transforming terahertz waveforms to improve the accuracy of these comparisons. The concepts developed in this dissertation directly apply to terahertz spectroscopy, but also carry implications for other spectroscopy methods, from Raman to mass spectrometry. For example, these techniques could help to lower the rate of false positives at airport security checkpoints. This dissertation also examines the implementation of several of these methods as a way to realize a fully self-contained, handheld, battery-operated terahertz spectrometer. This device also employs techniques to allow minimally-trained operators use terahertz to detect different substances of interest. It functions as a proof-of-concept of the true benefits of the improvements that have been developed in this dissertation.

  13. Terahertz spectroscopy of two-dimensional subwavelength plasmonic structures

    Energy Technology Data Exchange (ETDEWEB)

    Azad, Abul K [Los Alamos National Laboratory; Chen, Houtong [Los Alamos National Laboratory; Taylor, Antoinette [Los Alamos National Laboratory; O' Hara, John F [Los Alamos National Laboratory; Han, Jiaguang [OSU; Lu, Xinchao [OSU; Zhang, Weili [OSU

    2009-01-01

    The fascinating properties of plasmonic structures have had significant impact on the development of next generation ultracompact photonic and optoelectronic components. We study two-dimensional plasmonic structures functioning at terahertz frequencies. Resonant terahertz response due to surface plasmons and dipole localized surface plasmons were investigated by the state-of-the-art terahertz time domain spectroscopy (THz-TDS) using both transmission and reflection configurations. Extraordinary terahertz transmission was demonstrated through the subwavelength metallic hole arrays made from good conducting metals as well as poor metals. Metallic arrays m!lde from Pb, generally a poor metal, and having optically thin thicknesses less than one-third of a skin depth also contributed in enhanced THz transmission. A direct transition of a surface plasmon resonance from a photonic crystal minimum was observed in a photo-doped semiconductor array. Electrical controls of the surface plasmon resonances by hybridization of the Schottkey diode between the metallic grating and the semiconductor substrate are investigated as a function of the applied reverse bias. In addition, we have demonstrated photo-induced creation and annihilation of surface plasmons with appropriate semiconductors at room temperature. According to the Fano model, the transmission properties are characterized by two essential contributions: resonant excitation of surface plasmons and nonresonant direct transmission. Such plasmonic structures may find fascinating applications in terahertz imaging, biomedical sensing, subwavelength terahertz spectroscopy, tunable filters, and integrated terahertz devices.

  14. Squeezing terahertz light into nanovolumes: Nanoantenna enhanced terahertz spectroscopy (NETS) of semiconductor quantum dots

    KAUST Repository

    Toma, Andrea; Tuccio, Salvatore; Prato, Mirko; De Donato, Francesco; Perucchi, Andrea; Di Pietro, Paola; Marras, Sergio; Liberale, Carlo; Proietti Zaccaria, Remo; De Angelis, Francesco De; Manna, Liberato; Lupi, Stefano; Di Fabrizio, Enzo M.; Razzari, Luca

    2015-01-01

    Terahertz spectroscopy has vast potentialities in sensing a broad range of elementary excitations (e.g., collective vibrations of molecules, phonons, excitons, etc.). However, the large wavelength associated with terahertz radiation (about 300 μm

  15. Application of Terahertz Attenuated Total Reflection Spectroscopy to Detect Changes in the Physical Properties of Lactose during the Lubrication Process Required for Drug Formulation.

    Science.gov (United States)

    Dohi, Masafumi; Momose, Wataru; Yamashita, Kazunari; Hakomori, Tadashi; Sato, Shusaku; Noguchi, Shuji; Terada, Katsuhide

    2017-02-01

    Manufacturing the solid dosage form of an orally administered drug requires lubrication to enhance manufacturability, ensuring that critical quality attributes such as disintegration and dissolution of the drug product are maintained during manufacture. Here, to evaluate lubrication performance during manufacture, we used terahertz attenuated total reflection (THz-ATR) spectroscopy to detect differences in the physical characteristics of the lubricated powder. We applied a simple formulation prepared by blending granulated lactose as filler with magnesium stearate as lubricant. A flat tablet was prepared using the lubricated powder to acquire sharp THz-ATR absorption peaks of the samples. First, we investigated the effects of lubricant concentration and compression pressure on preparation of the tablet and then determined the effect of the pressure applied to samples in contact with the ATR prism on sample absorption amplitude. We focused on the differences in the magnitudes of spectra at the lactose-specific frequency. Second, we conducted the dynamic lubrication process using a 120-L mixer to investigate differences in the magnitudes of absorption corresponding to the lactose-specific frequency during lubrication. In both studies, enriching the lubricated powder with a higher concentration of magnesium stearate or prolonging blending time correlated with higher magnitudes of spectra at the lactose-specific frequency. Further, in the dynamic lubrication study, the wettability and disintegration time of the tablets were compared with the absorption spectra amplitudes at the lactose-specific frequency. We conclude that THz-ATR spectroscopy is useful for detecting differences in densities caused by a change in the physical properties of lactose during lubrication.

  16. Extending applicability of terahertz spectroscopy for biosensing

    Science.gov (United States)

    Parthasarathy, Ramakrishnan

    Terahertz (THz) vibrational resonance spectroscopy has recently emerged as a promising technique for fingerprinting biological molecules. Absorption spectra in this frequency range (0.1-10 THz) reflect molecular internal vibrations involving the weakest hydrogen bonds and/or non-bonded interactions, which are species specific. Of prime importance is improving detection sensitivity of molecules with low absorption characteristics in the THz gap. Also of importance is the characterization of biological molecules in the THz gap (10-25 cm-1) by physical parameters (refractive index and absorption coefficient) rather than sample dependent parameters (transmission, reflection) and extending spectroscopy to the low THz range where remote sensing is most viable. To address the sensitivity issue, it is shown that periodic arrays of rectangular slots with subwavelength width provide for local electromagnetic field enhancements due to edge effects in the low frequency range of interest, 10-25 cm-1 (300-750 GHz). Periodic structures of Au, doped Si and InSb were studied. InSb is confirmed to offer the highest results with the local power enhancements on the order of 1100 at frequency 14 cm -1. InSb and Si have large skin depths in the frequency range of interest and so the analysis of their structures was done through the Fourier expansion method of field diffracted from gratings. Au however has small skin depths at these frequencies compared to the thickness. Surface impedance boundary conditions were employed to model the Au structure, for which the Fourier expansion method was unsuitable owing to the huge magnitude of Au permittivity. The applications possibly include development of novel bio-sensors, with the strongly enhanced local electromagnetic fields leading to increased detection sensitivity, and monitoring biophysical processes such as DNA denaturation. Transmission and reflection data from parallel, independent experiments are utilized in the Interference

  17. Terahertz wave reflective sensing and imaging

    Science.gov (United States)

    Zhong, Hua

    Sensing and imaging technologies using terahertz (THz) radiation have found diverse applications as they approach maturity. Since the burgeoning of this technique in the 1990's, many THz sensing and imaging investigations have been designed and conducted in transmission geometry, which provides sufficient phase and amplitude contrast for the study of the spectral properties of targets in the THz domain. Driven by rising expectations that THz technology will be a potential candidate in the next generation of security screening, remote sensing, biomedical imaging and non-destructive testing (NDT), most THz sensing and imaging modalities are being extended to reflection geometry, which offers unique and adaptive solutions, and multi-dimensional information in many real scenarios. This thesis takes an application-focused approach to the advancement of THz wave reflective sensing and imaging systems: The absorption signature of the explosive material hexahydro-1,3,5-trinitro-1,3,5triazine (RDX) is measured at 30 m---the longest standoff distance so far attained by THz time-domain spectroscopy (THz-TDS). The standoff distance sensing ability of THz-TDS is investigated along with discussions specifying the influences of a variety of factors such as propagation distance, water vapor absorption and collection efficiency. Highly directional THz radiation from four-wave mixing in laser-induced air plasmas is first observed and measured, which provides a potential solution for the atmospheric absorption effect in standoff THz sensing. The simulations of the beam profiles also illuminate the underlying physics behind the interaction of the optical beam with the plasma. THz wave reflective spectroscopic focal-plane imaging is realized the first time. Absorption features of some explosives and related compounds (ERCs) and biochemical materials are identified by using adaptive feature extraction method. Good classification results using multiple pattern recognition methods are

  18. Terahertz spectroscopy applied to food model systems

    DEFF Research Database (Denmark)

    Møller, Uffe

    Water plays a crucial role in the quality of food. Apart from the natural water content of a food product, the state of that water is very important. Water can be found integrated into the biological material or it can be added during production of the product. Currently it is difficult...... to differentiate between these types of water in subsequent quality controls. This thesis describes terahertz time-domain spectroscopy applied on aqueous food model systems, with particular focus on ethanol-water mixtures and confined water pools in inverse micelles....

  19. Resonant Dipole Nanoantenna Arrays for Enhanced Terahertz Spectroscopy

    KAUST Repository

    Toma, A.

    2015-08-04

    Our recent studies on dipole nanoantenna arrays resonating in the terahertz frequency range (0.1 – 10 THz) will be presented. The main near- and far-field properties of these nanostructures will be shown and their application in enhanced terahertz spectroscopy of tiny quantities of nanomaterials will be discussed.

  20. Sensing of phase transition in medium with terahertz pulsed spectroscopy

    International Nuclear Information System (INIS)

    Zaytsev, Kirill I; Fokina, Irina N; Fedorov, Aleksey K; Yurchenko, Stanislav O

    2014-01-01

    Phase state identification and phase transition registration in condensed matter are significant applications of terahertz spectroscopy. A set of fundamental and applied problems are associated with the phase state problem. Our report is devoted to the experimental analysis of the spectral characteristics of water and water solution during the phase transition from the solid state to the liquid state via the method of terahertz pulsed spectroscopy. In this work transformation of the sample spectral characteristics during the phase transition were observed and discussed. Possible application of terahertz pulsed spectroscopy as an effective instrument for phase transition sensing was considered

  1. Metamaterial-Enhanced Nonlinear Terahertz Spectroscopy

    Directory of Open Access Journals (Sweden)

    Zhang X.

    2013-03-01

    Full Text Available We demonstrate large nonlinear terahertz responses in the gaps of metamaterial split ring resonators in several materials and use nonlinear THz transmission and THz-pump/THz-probe spectroscopy to study the nonlinear responses and dynamics. We use the field enhancement in the SRR gaps to initiate high-field phenomena at lower incident fields. In vanadium dioxide, we drive the insulator-to-metal phase transition with high-field THz radiation. The film conductivity increases by over two orders of magnitude and the phase transition occurs on a several picosecond timescale. In gallium arsenide, we observe high-field transport phenomena, including mobility saturation and impact ionization. The carrier density increases by up to ten orders of magnitude at high fields. At the highest fields, we demonstrate THz-induced damage in both vanadium dioxide and gallium arsenide.

  2. High-resolution broadband terahertz spectroscopy via electronic heterodyne detection of photonically generated terahertz frequency comb.

    Science.gov (United States)

    Pavelyev, D G; Skryl, A S; Bakunov, M I

    2014-10-01

    We report an alternative approach to the terahertz frequency-comb spectroscopy (TFCS) based on nonlinear mixing of a photonically generated terahertz pulse train with a continuous wave signal from an electronic synthesizer. A superlattice is used as a nonlinear mixer. Unlike the standard TFCS technique, this approach does not require a complex double-laser system but retains the advantages of TFCS-high spectral resolution and wide bandwidth.

  3. Electrically Tunable Reflective Terahertz Phase Shifter Based on Liquid Crystal

    Science.gov (United States)

    Yang, Jun; Xia, Tianyu; Jing, Shuaicheng; Deng, Guangsheng; Lu, Hongbo; Fang, Yong; Yin, Zhiping

    2018-02-01

    We present a reflective spatial phase shifter which operates at terahertz regime above 325 GHz. The controllable permittivity of the nematic liquid crystals was utilized to realize a tunable terahertz (THz) reflective phase shifter. The reflective characteristics of the terahertz electromagnetic waves and the liquid crystal parameters were calculated and analyzed. We provide the simulation results for the effect of the incident angle of the plane wave on the reflection. The experiment was carried out considering an array consisting of 30 × 30 patch elements, printed on a 20 × 20 mm quartz substrate with 1-mm thickness. The phase shifter provides a tunable phase range of 300° over the frequency range of 325 to 337.6 GHz. The maximum phase shift of 331° is achieved at 330 GHz. The proposed phase shifter is a potential candidate for THz applications, particularly for reconfigurable reflectarrays.

  4. Drug detection by terahertz time-domain spectroscopy

    International Nuclear Information System (INIS)

    Duan Ruixin; Zhu Yiming; Zhao Hongwei

    2013-01-01

    Due to unique spectral region, functional imaging ability, excellent penetration and safety characteristics of terahertz radiation, the terahertz technology rapidly becomes a vital method to detect and analyze drugs. In this paper, firstly, we identify the functional groups of anti-diabetic drugs by density functional theory (DFT), HIPHOP models and experimental results from terahertz time-domain spectroscopy measurements. Secondly, we identify four kinds of herbs of radix curcumae by using the support vector machine (SVM) analysis. Besides, we analyze the absorption of anhydrous and hydrous glucose, and determine the state of water in the crystalized D-glucose·H 2 O through the results of differential scanning calorimetry measurement. Finally, we summarize the advantages and disadvantages of terahertz time-domain spectroscopy method in drug detection and analyzing. (authors)

  5. Invisible Security Printing on Photoresist Polymer Readable by Terahertz Spectroscopy

    OpenAIRE

    Hee Jun Shin; Min-Cheol Lim; Kisang Park; Sae-Hyung Kim; Sung-Wook Choi; Gyeongsik Ok

    2017-01-01

    We experimentally modulate the refractive index and the absorption coefficient of an SU-8 dry film in the terahertz region by UV light (362 nm) exposure with time dependency. Consequently, the refractive index of SU-8 film is increased by approximately 6% after UV light exposure. Moreover, the absorption coefficient also changes significantly. Using the reflective terahertz imaging technique, in addition, we can read security information printed by UV treatment on an SU-8 film that is transpa...

  6. TERAHERTZ REFLECTANCE SPECTRA OF SKIN DERMATITIS AND MORPHOLOGICAL CHANGES

    Directory of Open Access Journals (Sweden)

    E. A. Strepitov

    2013-05-01

    Full Text Available The article deals withthe diagnostics possibility of dermatitis and morphological changes of human skin using terahertz frequency range equal to 2,0¸0,05 THz. Features of different types of human skin diseases occur in vivo over the entire frequency range, especially in the field of vibration: 2,0¸1,5 THz. They were caused by the backscattering on skin new formations in its upper layers. In terahertz reflection spectra spectral lines of different dermatitis, age spots, haematoma are well distinguishable. Terahertz radiation penetrates well through the medical bandages. At the same time in a single scan, lasting about one minute, the spectrum is processed not only of the bandages, but of different skin layers.

  7. Time-resolved terahertz spectroscopy of semiconductor nanostructures

    DEFF Research Database (Denmark)

    Porte, Henrik

    This thesis describes time-resolved terahertz spectroscopy measurements on various semiconductor nanostructures. The aim is to study the carrier dynamics in these nanostructures on a picosecond timescale. In a typical experiment carriers are excited with a visible or near-infrared pulse and by me......This thesis describes time-resolved terahertz spectroscopy measurements on various semiconductor nanostructures. The aim is to study the carrier dynamics in these nanostructures on a picosecond timescale. In a typical experiment carriers are excited with a visible or near-infrared pulse...... and by measuring the transmission of a terahertz probe pulse, the photoconductivity of the excited sample can be obtained. By changing the relative arrival time at the sample between the pump and the probe pulse, the photoconductivity dynamics can be studied on a picosecond timescale. The rst studied semiconductor...

  8. Nanoantenna enhanced terahertz spectroscopy of a monolayer of cadmium selenide quantum dots

    KAUST Repository

    Razzari, Luca; Toma, Andrea; Tuccio, Salvatore; Prato, Mirko; De Donato, Francesco; Perucchi, Andrea; Di Pietro, Paola; Marras, Sergio; Liberale, Carlo; Proietti Zaccaria, Remo; De Angelis, Francesco De; Manna, Liberato; Lupi, Stefano; Di Fabrizio, Enzo M.

    2014-01-01

    Exploiting the localization and enhancement capabilities of terahertz resonant dipole nanoantennas coupled through nanogaps, we present an effective method to perform terahertz spectroscopy on an extremely small number of nano-objects.

  9. Squeezing terahertz light into nanovolumes: Nanoantenna enhanced terahertz spectroscopy (NETS) of semiconductor quantum dots

    KAUST Repository

    Toma, Andrea

    2015-01-14

    Terahertz spectroscopy has vast potentialities in sensing a broad range of elementary excitations (e.g., collective vibrations of molecules, phonons, excitons, etc.). However, the large wavelength associated with terahertz radiation (about 300 μm at 1 THz) severely hinders its interaction with nano-objects, such as nanoparticles, nanorods, nanotubes, and large molecules of biological relevance, practically limiting terahertz studies to macroscopic ensembles of these compounds, in the form of thick pellets of crystallized molecules or highly concentrated solutions of nanomaterials. Here we show that chains of terahertz dipole nanoantennas spaced by nanogaps of 20 nm allow retrieving the spectroscopic signature of a monolayer of cadmium selenide quantum dots, a significant portion of the signal arising from the dots located within the antenna nanocavities. A Fano-like interference between the fundamental antenna mode and the phonon resonance of the quantum dots is observed, accompanied by an absorption enhancement factor greater than one million. NETS can find immediate applications in terahertz spectroscopic studies of nanocrystals and molecules at extremely low concentrations. Furthermore, it shows a practicable route toward the characterization of individual nano-objects at these frequencies.

  10. Terahertz time-domain spectroscopy of edible oils

    Science.gov (United States)

    Dinovitser, Alex; Valchev, Dimitar G.; Abbott, Derek

    2017-06-01

    Chemical degradation of edible oils has been studied using conventional spectroscopic methods spanning the spectrum from ultraviolet to mid-IR. However, the possibility of morphological changes of oil molecules that can be detected at terahertz frequencies is beginning to receive some attention. Furthermore, the rapidly decreasing cost of this technology and its capability for convenient, in situ measurement of material properties, raises the possibility of monitoring oil during cooking and processing at production facilities, and more generally within the food industry. In this paper, we test the hypothesis that oil undergoes chemical and physical changes when heated above the smoke point, which can be detected in the 0.05-2 THz spectral range, measured using the conventional terahertz time-domain spectroscopy technique. The measurements demonstrate a null result in that there is no significant change in the spectra of terahertz optical parameters after heating above the smoke point for 5 min.

  11. Invited Review Terahertz Transmission, Scattering, Reflection, and Absorption—the Interaction of THz Radiation with Soils

    Science.gov (United States)

    Lewis, R. A.

    2017-07-01

    Terahertz radiation has been proposed as a useful tool in the study of soils and related materials from such diverse perspectives as detection of non-metallic landmines to improving soil fertility by agricultural charcoals produced by pyrolysis of organic material. The main barrier to such applications is that soils are rather opaque at terahertz frequencies. In this article, the main findings to date on the interaction of terahertz radiation with soils are reviewed, organized around the four phenomena of terahertz: transmission, scattering, reflection, and absorption. Terahertz transmission through soils is generally low and decreases with frequency. Terahertz scattering is evident in many THz-soil interactions, as the wavelength of the radiation is of the order of the particle size. Terahertz reflection is important to communications as these develop from the GHz into the THz band. Terahertz absorption on diluted soil samples has been demonstrated to be effective in identifying soil constituents, such as aromatic compounds, and soil contaminants, such as pesticides.

  12. Ultrabroadband terahertz spectroscopy of a liquid crystal

    DEFF Research Database (Denmark)

    Vieweg, N.; Fischer, B. M.; Reuter, M.

    2012-01-01

    Liquid crystals (LCs) are becoming increasingly important for applications in the terahertz frequency range. A detailed understanding of the spectroscopic parameters of these materials over a broad frequency range is crucial in order to design customized LC mixtures for improved performance. We p...... show that the spectra are dominated by multiple strong spectral features mainly at frequencies above 4 THz, originating from intramolecular vibrational modes of the weakly LC molecules....

  13. Discrimination of genetically modified sugar beets based on terahertz spectroscopy

    Science.gov (United States)

    Chen, Tao; Li, Zhi; Yin, Xianhua; Hu, Fangrong; Hu, Cong

    2016-01-01

    The objective of this paper was to apply terahertz (THz) spectroscopy combined with chemometrics techniques for discrimination of genetically modified (GM) and non-GM sugar beets. In this paper, the THz spectra of 84 sugar beet samples (36 GM sugar beets and 48 non-GM ones) were obtained by using terahertz time-domain spectroscopy (THz-TDS) system in the frequency range from 0.2 to 1.2 THz. Three chemometrics methods, principal component analysis (PCA), discriminant analysis (DA) and discriminant partial least squares (DPLS), were employed to classify sugar beet samples into two groups: genetically modified organisms (GMOs) and non-GMOs. The DPLS method yielded the best classification result, and the percentages of successful classification for GM and non-GM sugar beets were both 100%. Results of the present study demonstrate the usefulness of THz spectroscopy together with chemometrics methods as a powerful tool to distinguish GM and non-GM sugar beets.

  14. Invisible Security Printing on Photoresist Polymer Readable by Terahertz Spectroscopy

    Directory of Open Access Journals (Sweden)

    Hee Jun Shin

    2017-12-01

    Full Text Available We experimentally modulate the refractive index and the absorption coefficient of an SU-8 dry film in the terahertz region by UV light (362 nm exposure with time dependency. Consequently, the refractive index of SU-8 film is increased by approximately 6% after UV light exposure. Moreover, the absorption coefficient also changes significantly. Using the reflective terahertz imaging technique, in addition, we can read security information printed by UV treatment on an SU-8 film that is transparent in the visible spectrum. From these results, we successfully demonstrate security printing and reading by using photoresist materials and the terahertz technique. This investigation would provide a new insight into anti-counterfeiting applications in fields that need security.

  15. Detection of Ionic liquid using terahertz time-domain spectroscopy

    Science.gov (United States)

    Wang, Cuicui; Zhao, Xiaojing; Liu, Shangjian; Zuo, Jian; Zhang, Cunlin

    2018-01-01

    Terahertz (THz, THz+1012Hz) spectroscopy is a far-infrared analytical technology with spectral bands locating between microware and infrared ranges. Being of excellent transmission, non-destruction and high discrimination, this technology has been applied in various fields such as physics, chemistry, nondestructive detection, communication, biomedicine public security. Terahertz spectrum is corresponding with vibration and rotation of liquid molecules, which is suitable to identify and study the liquid molecular dynamics. It is as a powerful spectral detection technology, terahertz time-domain spectroscopy is widely used in solution detection. can enable us to extract the material parameters or dielectric spectrum that show material micro-structure and dynamics by measuring amplitude and phase from coherent terahertz pulses. Ionic liquid exists in most biological tissues, and it is very important for life. It has recently been suggested that near-fired terahertz ionic contrast microscopy can be employed to image subtle changes in ionic concentrations arising from neuronal activity. In this paper, we detected Ionic liquid with different concentrations at room temperature by THz-TDS technique in the range of 0.2-1.5 THz. The liquid cell with a thickness of 0.2mm is made of quartz. The absorption coefficient, refractive index and dielectric function of solutions can be extracted based on THz-TDS. We use an expanded model for fitting the dielectric function based on a combination of a Debye relation for the anions and cations. We find A linear increase of the real and imaginary part of the dielectric function compared with pure water with increasing ion concentrations. A good agreement between the model and the experimental results is obtained. By means of dielectric relaxation process, it was found that the characteristic time of molecular movement and the information related to the liquid molecular structure and movement was obtained.

  16. Continuous wave terahertz reflection imaging of human colorectal tissue

    Science.gov (United States)

    Doradla, Pallavi; Alavi, Karim; Joseph, Cecil S.; Giles, Robert H.

    2013-03-01

    Continuous wave terahertz (THz) imaging has the potential to offer a safe, non-ionizing, and nondestructive medical imaging modality for delineating colorectal cancer. Fresh excisions of normal colon tissue were obtained from surgeries performed at the University of Massachusetts Medical School, Worcester. Reflection measurements of thick sections of colorectal tissues, mounted in an aluminum sample holder, were obtained for both fresh and formalin fixed tissues. The two-dimensional reflection images were acquired by using an optically pumped far-infrared molecular gas laser operating at 584 GHz with liquid Helium cooled silicon bolometer detector. Using polarizers in the experiment both co-polarized and cross-polarized remittance form the samples was collected. Analysis of the images showed the importance of understanding the effects of formalin fixation while determining reflectance level of tissue response. The resulting co- and cross-polarized images of both normal and formalin fixed tissues showed uniform terahertz response over the entire sample area. Initial measurements indicated a co-polarized reflectance of 16%, and a cross-polarized reflectance of 0.55% from fresh excisions of normal colonic tissues.

  17. Highly Resolved Sub-Terahertz Vibrational Spectroscopy of Biological Macromolecules and Bacteria Cells

    Science.gov (United States)

    2016-07-01

    HIGHLY RESOLVED SUB-TERAHERTZ VIBRATIONAL SPECTROSCOPY OF BIOLOGICAL MACROMOLECULES AND BACTERIA CELLS ECBC...SUBTITLE Highly Resolved Sub-Terahertz Vibrational Spectroscopy of Biological Macromolecules and Bacteria Cells 5a. CONTRACT NUMBER W911SR-14-P...22 4.3 Bacteria THz Study

  18. Terahertz transmission properties of silicon wafers using continuous-wave terahertz spectroscopy

    Science.gov (United States)

    Kim, Chihoon; Ahn, Jae Sung; Ji, Taeksoo; Eom, Joo Beom

    2017-04-01

    We present the spectral properties of Si wafers using continuous-wave terahertz (CW-THz) spectroscopy. By using a tunable laser source and a fixed distributed-feedback laser diode (DFB-LD), a stably tunable beat source for CW-THz spectroscopy system can be implemented. THz radiation is generated in the frequency range of 100 GHz-800 GHz by photomixing in a photoconductive antenna. We also measured CW-THz waveforms by changing the beat frequency and confirmed repeatability through repeated measurement. We calculated the peaks of the THz frequency by taking fast Fourier transforms (FFTs) of measured THz waveforms. The feasibility of CW-THz spectroscopy is demonstrated by the THz spectra of Si wafers with different resistivities, mobilities, and carrier concentrations. The results show that Si wafers with a lower resistivity absorb more THz waves. Thus, we expect our CW-THz system to have the advantage of being able to perform fast non-destructive analysis.

  19. Terahertz transmission properties of silicon wafers using continuous-wave terahertz spectroscopy

    International Nuclear Information System (INIS)

    Kim, Chihoon; Ahn, Jae Sung; Eom, Joo Beom; Ji, Taeksoo

    2017-01-01

    We present the spectral properties of Si wafers using continuous-wave terahertz (CW-THz) spectroscopy. By using a tunable laser source and a fixed distributed-feedback laser diode (DFB-LD), a stably tunable beat source for CW-THz spectroscopy system can be implemented. THz radiation is generated in the frequency range of 100 GHz–800 GHz by photomixing in a photoconductive antenna. We also measured CW-THz waveforms by changing the beat frequency and confirmed repeatability through repeated measurement. We calculated the peaks of the THz frequency by taking fast Fourier transforms (FFTs) of measured THz waveforms. The feasibility of CW-THz spectroscopy is demonstrated by the THz spectra of Si wafers with different resistivities, mobilities, and carrier concentrations. The results show that Si wafers with a lower resistivity absorb more THz waves. Thus, we expect our CW-THz system to have the advantage of being able to perform fast non-destructive analysis. (paper)

  20. Terahertz time-domain spectroscopy and imaging of artificial RNA

    DEFF Research Database (Denmark)

    Fischer, Bernd M.; Hoffmann, Matthias; Helm, Hanspeter

    2005-01-01

    We use terahertz time-domain spectroscopy (THz-TDS) to measure the far-infrared dielectric function of two artificial RNA single strands, composed of polyadenylic acid (poly-A) and polycytidylic acid (poly-C). We find a significant difference in the absorption between the two types of RNA strands......, and we show that we can use this difference to record images of spot arrays of the RNA strands. Under controlled conditions it is possible to use the THz image to distinguish between the two RNA strands. We discuss the requirements to sample preparation imposed by the lack of sharp spectral features...

  1. Novel concepts for terahertz waveguide spectroscopy

    DEFF Research Database (Denmark)

    Jepsen, Peter Uhd

    2009-01-01

    . With such waveguides we demonstrate that it is possible to perform quantitative spectroscopy on very small volumes of sample material inside the PPWG. Using continuous-wave as well as femtosecond excitation we inject carriers into semiconductor material in the transparent PPWG, and perform static as well as transient...

  2. Detection of Poisonous Herbs by Terahertz Time-Domain Spectroscopy

    Science.gov (United States)

    Zhang, H.; Li, Z.; Chen, T.; Liu, J.-J.

    2018-03-01

    The aim of this paper is the application of terahertz (THz) spectroscopy combined with chemometrics techniques to distinguish poisonous and non-poisonous herbs which both have a similar appearance. Spectra of one poisonous and two non-poisonous herbs (Gelsemium elegans, Lonicera japonica Thunb, and Ficus Hirta Vahl) were obtained in the range 0.2-1.4 THz by using a THz time-domain spectroscopy system. Principal component analysis (PCA) was used for feature extraction. The prediction accuracy of classification is between 97.78 to 100%. The results demonstrate an efficient and applicative method to distinguish poisonous herbs, and it may be implemented by using THz spectroscopy combined with chemometric algorithms.

  3. Terahertz pulse imaging in reflection geometry of human skin cancer and skin tissue

    International Nuclear Information System (INIS)

    Woodward, Ruth M; Cole, Bryan E; Wallace, Vincent P; Pye, Richard J; Arnone, Donald D; Linfield, Edmund H; Pepper, Michael

    2002-01-01

    We demonstrate the application of terahertz pulse imaging (TPI) in reflection geometry for the study of skin tissue and related cancers both in vitro and in vivo. The sensitivity of terahertz radiation to polar molecules, such as water, makes TPI suitable for studying the hydration levels in the skin and the determination of the lateral spread of skin cancer pre-operatively. By studying the terahertz pulse shape in the time domain we have been able to differentiate between diseased and normal tissue for the study of basal cell carcinoma (BCC). Basal cell carcinoma has shown a positive terahertz contrast, and inflammation and scar tissue a negative terahertz contrast compared to normal tissue. In vivo measurements on the stratum corneum have enabled visualization of the stratum corneum-epidermis interface and the study of skin hydration levels. These results demonstrate the potential of terahertz pulse imaging for the study of skin tissue and its related disorders, both in vitro and in vivo

  4. Transient photoconductivity in InGaN/GaN multiple quantum wells, measured by time-resolved terahertz spectroscopy

    DEFF Research Database (Denmark)

    Porte, Henrik; Turchinovich, Dmitry; Cooke, David

    2009-01-01

    Terahertz conductivity of InGaN/GaN MQWs was studied by time-resolved terahertz spectroscopy. Restoration of the built-in piezoelectric field leads to a nonexponential carrier density decay. Terahertz conductivity spectrum is described by the Drude-Smith......Terahertz conductivity of InGaN/GaN MQWs was studied by time-resolved terahertz spectroscopy. Restoration of the built-in piezoelectric field leads to a nonexponential carrier density decay. Terahertz conductivity spectrum is described by the Drude-Smith...

  5. Intense Terahertz Sources for 2D Spectroscopy

    DEFF Research Database (Denmark)

    Pedersen, Pernille Klarskov

    in a molecular dynamics (MD) simulation. With this THz induced nonlinear responses and mode couplings in CsI and sucrose are investigated for increasing field strengths, and it is found that these occur for sucrose when the field strength is in the MV/cm range. THz sources based on LiNbO3, DAST, DSTMS and 2...... observed having a Gaussian beam profile. In addition to the intense THz pulses focused in free-space in order to achieve the highest possible field strength, it is shown that resonant microslit arrays can be used to enhance the THz field, and with the possibility of mounting crystalline samples inside...... the metallic slits, this is proposed as a combined spectroscopy system for investigating high-field phenomena. With a carefully optimized design, the slit resonance can be coupled to the lattice modes of the array structure to achieve a field enhancement of more than 35 times, which is approximately 60 % more...

  6. Relaxation and crystallization of amorphous carbamazepine studied by terahertz pulsed spectroscopy

    DEFF Research Database (Denmark)

    Zeitler, J Axel; Taday, Philip F; Pepper, Michael

    2007-01-01

    At the example of carbamazepine the crystallization of a small organic molecule from its amorphous phase was studied using in situ variable temperature terahertz pulsed spectroscopy (TPS). Even though terahertz spectra of disordered materials in the glassy state exhibit no distinct spectral featu...

  7. Semiconductor Nonlinear Dynamics Study by Broadband Terahertz Spectroscopy

    Science.gov (United States)

    Ho, I.-Chen

    Semiconductor nonlinearity in the terahertz (THz) frequency range has been attracting considerable attention due to the recent development of high-power semiconductor-based nanodevices. However, the underlying physics concerning carrier dynamics in the presence of high-field THz transients is still obscure. This thesis introduces an ultrafast, time-resolved THz pump/THz probe approach to the study of semiconductor properties in the nonlinear regime. The carrier dynamics regarding two mechanisms, intervalley scattering and impact ionization, is observed for doped InAs on a sub-picosecond time scale. In addition, polaron modulation driven by intense THz pulses is experimentally and theoretically investigated. The observed polaron dynamics verifies the interaction between energetic electrons and a phonon field. In contrast to previous work which reports optical phonon responses, acoustic phonon modulations are addressed in this study. A further understanding of the intense field interacting with solid materials will accelerate the development of semiconductor devices. This thesis starts with the design and performance of a table-top THz spectrometer which has the advantages of ultra-broad bandwidth (one order higher bandwidth compared to a conventional ZnTe sensor) and high electric field strength (>100 kV/cm). Unlike the conventional THz time-domain spectroscopy, the spectrometer integrates a novel THz air-biased-coherent-detection (THz-ABCD) technique and utilizes selected gases as THz emitters and sensors. In comparison with commonly used electro-optic (EO) crystals or photoconductive (PC) dipole antennas, the gases have the benefits of no phonon absorption as existing in EO crystals and no carrier life time limitation as observed in PC dipole antennas. The newly development THz-ABCD spectrometer with a strong THz field strength capability provides a platform for various research topics especially on the nonlinear carrier dynamics of semiconductors. Two mechanisms

  8. Gradient metasurface for four-direction anomalous reflection in terahertz

    Science.gov (United States)

    Wang, Jiao; Jiang, Yannan

    2018-06-01

    In this paper, a four-direction anomalous reflection metasurface is proposed. The basic cells comprise of squares and circles, which are designed at various sizes and arranged in a super cell at regular spacing. Then, properly combining super cells molds a square phase gradient metasurface (PGM). It is mounted on an optical thickness gold mirror, which inhibits all light transmission. Markedly different from previously reported metasurfaces, the square PGM is characterized by four-direction reflection beams. It takes into consideration the normal incidence and the oblique incidence. For the normal incidence, that the degrees of the four reflection angles are identical is due to the x, - x, y and - y directional discontinuous phase gradients, and lies on the symmetric structure in the xoy plane, which is then revealed by the surface current distribution. Incident angles varying from -20° to 20°, the reflection angles are demonstrated in the oblique incidence. Moreover, the PGM is polarization-independent. The performance is attributed to the symmetry of structure, which is verified by Radar cross section. Simulated results prove that our method offers a simple and effective strategy for metasurface design in terahertz. The proposed PGM can aid in focused beams, steering beams, and shaped beams.

  9. Transmission and reflection properties of terahertz fractal metamaterials

    DEFF Research Database (Denmark)

    Malureanu, Radu; Lavrinenko, Andrei; Cooke, David

    2010-01-01

    We use THz time-domain spectroscopy to investigate transmission and reflection properties of metallic fractal metamaterial structures. We observe loss of free-space energy at certain resonance frequencies, indicating excitation of surface modes of the metamaterial.......We use THz time-domain spectroscopy to investigate transmission and reflection properties of metallic fractal metamaterial structures. We observe loss of free-space energy at certain resonance frequencies, indicating excitation of surface modes of the metamaterial....

  10. 3-D Printed Anti-Reflection Structures for the Terahertz Region

    Science.gov (United States)

    Bomba, Jarosław; Suszek, Jarosław; Makowski, Michał; Sobczyk, Artur; Sypek, Maciej

    2018-01-01

    Terahertz radiation has a growing number of applications in material characterization, where spectral fingerprinting and diffractive effects are the carriers of information. On the other hand, electromagnetic waves in the range of millimeters exhibit strong unwanted specular reflections, resulting in uncontrolled interferences. This problem is especially disturbing in the goniometric time-domain spectroscopy (TDS) configuration, where angular distribution of the field modified by the sample is altered by unwanted reflections. For this reason, low-cost anti-reflection layers are desired. Here, we present a simple way of designing and manufacturing one-sided and two-sided anti-reflection polyamide layers for the THz range. The structures were fabricated using 3-D printers based on selective laser sintering. We demonstrate experimentally in the goniometric time-domain spectroscopy the significant reduction of wavelength-dependent oscillations in Fabry-Perot configuration in the range between 0.1 and 0.3 THz. We also examine the influence of the anti-reflection layers on the distribution of THz energy in reflected, transmitted, and diffracted fields.

  11. 3D-Printed Broadband Dielectric Tube Terahertz Waveguide with Anti-Reflection Structure

    Science.gov (United States)

    Vogt, Dominik Walter; Leonhardt, Rainer

    2016-11-01

    We demonstrate broadband, low loss, and close-to-zero dispersion guidance of terahertz (THz) radiation in a dielectric tube with an anti-reflection structure (AR-tube waveguide) in the frequency range from 0.2 to 1.0 THz. The anti-reflection structure (ARS) consists of close-packed cones in a hexagonal lattice arranged on the outer surface of the tube cladding. The feature size of the ARS is in the order of the wavelength between 0.2 and 1.0 THz. The waveguides are fabricated with the versatile and cost efficient 3D-printing method. Terahertz time-domain spectroscopy (THz-TDS) measurements as well as 3D finite-difference time-domain simulations (FDTD) are performed to extensively characterize the AR-tube waveguides. Spectrograms, attenuation spectra, effective phase refractive indices, and the group-velocity dispersion parameters β 2 of the AR-tube waveguides are presented. Both the experimental and numerical results confirm the extended bandwidth and smaller group-velocity dispersion of the AR-tube waveguide compared to a low loss plain dielectric tube THz waveguide. The AR-tube waveguide prototypes show an attenuation spectrum close to the theoretical limit given by the infinite cladding tube waveguide.

  12. High-resolution reflection spectroscopy

    International Nuclear Information System (INIS)

    Ducloy, Martial

    1997-01-01

    In this article some recent developments in selective reflection spectroscopy is reviewed and the various ways to extend Doppler free techniques to this spectroscopic field is discussed. Its main feature is to probe atomic gas close to the cell boundaries

  13. Characteristics of Gadolinium Oxide Nanoparticles Using Terahertz Spectroscopy

    International Nuclear Information System (INIS)

    Lee, Dongkyu; Maeng, Inhee; Son, Joo-Hiuk; Oh, Seung Jae; Kim, Taekhoon; Cho, Byung Kyu; Lee, Kwangyeol

    2009-01-01

    The penetration property of the terahertz electromagnetic (THz) wave is relevant to its use. We used the THz wave spectroscopy system which easily penetrates some materials that do not contain water, e.g., plastic and ceramics. The system has been developed for several purposes, including measuring the properties of semiconductors and bio-materials, and detecting plastic bombs and ceramic knives at airports. It is also used for medical imaging systems, such as magnetic resonance imaging (MRI), at some research institutes. It can show not only the difference in amplitude, but also the difference of the phase of each point of sample. MRI technology usually uses contrast agents to enhance the quality of the image. Gadolinium diethylenetriamine pentaacetic acid (Gd-DTPA), made with a heavy metal ion, is commonly used as a clinical MRI contrast agent. Gadolinium oxide (Gd 2 O 3 ) nanoparticle is a new contrast agent. It serves to equip the core of each particle with antibodies or ligands. It can freely circulate in blood vessels without amassing in the liver or lungs. This study shows the characteristics of gadolinium oxide nanoparticles to further advance terahertz medical imaging.

  14. Characteristics of Gadolinium Oxide Nanoparticles Using Terahertz Spectroscopy (abstract)

    Science.gov (United States)

    Lee, Dongkyu; Maeng, Inhee; Oh, Seung Jae; Kim, Taekhoon; Cho, Byung Kyu; Lee, Kwangyeol; Son, Joo-Hiuk

    2009-04-01

    The penetration property of the terahertz electromagnetic (THz) wave is relevant to its use. We used the THz wave spectroscopy system which easily penetrates some materials that do not contain water, e.g., plastic and ceramics. The system has been developed for several purposes, including measuring the properties of semiconductors and bio-materials, and detecting plastic bombs and ceramic knives at airports. It is also used for medical imaging systems, such as magnetic resonance imaging (MRI), at some research institutes. It can show not only the difference in amplitude, but also the difference of the phase of each point of sample. MRI technology usually uses contrast agents to enhance the quality of the image. Gadolinium diethylenetriamine pentaacetic acid (Gd-DTPA), made with a heavy metal ion, is commonly used as a clinical MRI contrast agent. Gadolinium oxide (Gd2O3) nanoparticle is a new contrast agent. It serves to equip the core of each particle with antibodies or ligands. It can freely circulate in blood vessels without amassing in the liver or lungs. This study shows the characteristics of gadolinium oxide nanoparticles to further advance terahertz medical imaging.

  15. Non-invasive detection of murals with pulsed terahertz reflected imaging system

    Science.gov (United States)

    Yuan, Minjie; Sun, Wenfeng; Wang, Xinke; Ye, Jiasheng; Wang, Sen; Zhang, Qunxi; Zhang, Yan

    2015-11-01

    Pulsed terahertz reflected imaging technology has been expected to have great potential for the non-invasive analysis of artworks. In this paper, three types of defects hidden in the plaster used to simulate the cases of defects in the murals, have been investigated by a pulsed terahertz reflected imaging system. These preset defects include a circular groove, a cross-shaped slit and a piece of "Y-type" metal plate built in the plaster. With the terahertz reflective tomography, information about defects has been determined involving the thickness from the surface of sample to the built-in defect, the profile and distribution of the defect. Additionally, three-dimensional analyses have been performed in order to reveal the internal structure of defects. Terahertz reflective imaging can be applied to the defect investigation of the murals.

  16. Flexible manipulation of terahertz wave reflection using polarization insensitive coding metasurfaces.

    Science.gov (United States)

    Jiu-Sheng, Li; Ze-Jiang, Zhao; Jian-Quan, Yao

    2017-11-27

    In order to extend to 3-bit encoding, we propose notched-wheel structures as polarization insensitive coding metasurfaces to control terahertz wave reflection and suppress backward scattering. By using a coding sequence of "00110011…" along x-axis direction and 16 × 16 random coding sequence, we investigate the polarization insensitive properties of the coding metasurfaces. By designing the coding sequences of the basic coding elements, the terahertz wave reflection can be flexibly manipulated. Additionally, radar cross section (RCS) reduction in the backward direction is less than -10dB in a wide band. The present approach can offer application for novel terahertz manipulation devices.

  17. Reflective terahertz (THz) imaging: system calibration using hydration phantoms

    Science.gov (United States)

    Bajwa, Neha; Garritano, James; Lee, Yoon Kyung; Tewari, Priyamvada; Sung, Shijun; Maccabi, Ashkan; Nowroozi, Bryan; Babakhanian, Meghedi; Sanghvi, Sajan; Singh, Rahul; Grundfest, Warren; Taylor, Zachary

    2013-02-01

    Terahertz (THz) hydration sensing continues to gain traction in the medical imaging community due to its unparalleled sensitivity to tissue water content. Rapid and accurate detection of fluid shifts following induction of thermal skin burns as well as remote corneal hydration sensing have been previously demonstrated in vivo using reflective, pulsed THz imaging. The hydration contrast sensing capabilities of this technology were recently confirmed in a parallel 7 Tesla Magnetic Resonance (MR) imaging study, in which burn areas are associated with increases in local mobile water content. Successful clinical translation of THz sensing, however, still requires quantitative assessments of system performance measurements, specifically hydration concentration sensitivity, with tissue substitutes. This research aims to calibrate the sensitivity of a novel, reflective THz system to tissue water content through the use of hydration phantoms for quantitative comparisons of THz hydration imagery.Gelatin phantoms were identified as an appropriate tissue-mimicking model for reflective THz applications, and gel composition, comprising mixtures of water and protein, was varied between 83% to 95% hydration, a physiologically relevant range. A comparison of four series of gelatin phantom studies demonstrated a positive linear relationship between THz reflectivity and water concentration, with statistically significant hydration sensitivities (p hydration). The THz-phantom interaction is simulated with a three-layer model using the Transfer Matrix Method with agreement in hydration trends. Having demonstrated the ability to accurately and noninvasively measure water content in tissue equivalent targets with high sensitivity, reflective THz imaging is explored as a potential tool for early detection and intervention of corneal pathologies.

  18. Terahertz Time Domain Spectroscopy for Structure-II Gas Hydrates

    DEFF Research Database (Denmark)

    Takeya, Kei; Zhang, Caihong; Kawayama, Iwao

    2009-01-01

    For the nondestructive inspection of gas hydrates, terahertz (THz) time-domain spectroscopy (TDS) was applied to tetrahydrofuran (THF) hydrate and propane hydrate. The absorption of propane hydrate monotonically increases with frequency, similar to the case of ice, while THF hydrate has...... a characteristic broad absorption peak at 0.5 THz corresponding to the dipole moment of THF molecules. The refractive indices of THF and propane hydrates are 1.725 and 1.775 at 1 THz, respectively, and show a slight but clear difference from the refractive index of ice (1.79). THz-TDS is a potentially useful...... technique for the ondestructive inspection of gas hydrates. # 2009 The Japan Society of Applied Physics...

  19. Nondestructive Evaluation of Carbon Fiber Reinforced Polymer Composites Using Reflective Terahertz Imaging

    Directory of Open Access Journals (Sweden)

    Jin Zhang

    2016-06-01

    Full Text Available Terahertz (THz time-domain spectroscopy (TDS imaging is considered a nondestructive evaluation method for composite materials used for examining various defects of carbon fiber reinforced polymer (CFRP composites and fire-retardant coatings in the reflective imaging modality. We demonstrate that hidden defects simulated by Teflon artificial inserts are imaged clearly in the perpendicular polarization mode. The THz TDS technique is also used to measure the thickness of thin fire-retardant coatings on CFRP composites with a typical accuracy of about 10 micrometers. In addition, coating debonding is successfully imaged based on the time-delay difference of the time-domain waveforms between closely adhered and debonded sample locations.

  20. Terahertz imaging and spectroscopy based on hot electron bolometer (HEB) heterodyne detection

    Science.gov (United States)

    Gerecht, Eyal; You, Lixing

    2008-02-01

    Imaging and spectroscopy at terahertz frequencies have great potential for healthcare, plasma diagnostics, and homeland security applications. Terahertz frequencies correspond to energy level transitions of important molecules in biology and astrophysics. Terahertz radiation (T-rays) can penetrate clothing and, to some extent, can also penetrate biological materials. Because of their shorter wavelengths, they offer higher spatial resolution than do microwaves or millimeter waves. We are developing hot electron bolometer (HEB) mixer receivers for heterodyne detection at terahertz frequencies. HEB detectors provide unprecedented sensitivity and spectral resolution at terahertz frequencies. We describe the development of a two-pixel focal plane array (FPA) based on HEB technology. Furthermore, we have demonstrated a fully automated, two-dimensional scanning, passive imaging system based on our HEB technology operating at 0.85 THz. Our high spectral resolution terahertz imager has a total system noise equivalent temperature difference (NEΔT) value of better than 0.5 K and a spatial resolution of a few millimeters. HEB technology is becoming the basis for advanced terahertz imaging and spectroscopic technologies for the study of biological and chemical agents over the entire terahertz spectrum.

  1. Discrimination of transgenic soybean seeds by terahertz spectroscopy

    Science.gov (United States)

    Liu, Wei; Liu, Changhong; Chen, Feng; Yang, Jianbo; Zheng, Lei

    2016-10-01

    Discrimination of genetically modified organisms is increasingly demanded by legislation and consumers worldwide. The feasibility of a non-destructive discrimination of glyphosate-resistant and conventional soybean seeds and their hybrid descendants was examined by terahertz time-domain spectroscopy system combined with chemometrics. Principal component analysis (PCA), least squares-support vector machines (LS-SVM) and PCA-back propagation neural network (PCA-BPNN) models with the first and second derivative and standard normal variate (SNV) transformation pre-treatments were applied to classify soybean seeds based on genotype. Results demonstrated clear differences among glyphosate-resistant, hybrid descendants and conventional non-transformed soybean seeds could easily be visualized with an excellent classification (accuracy was 88.33% in validation set) using the LS-SVM and the spectra with SNV pre-treatment. The results indicated that THz spectroscopy techniques together with chemometrics would be a promising technique to distinguish transgenic soybean seeds from non-transformed seeds with high efficiency and without any major sample preparation.

  2. Quantify Glucose Level in Freshly Diabetic's Blood by Terahertz Time-Domain Spectroscopy

    Science.gov (United States)

    Chen, Hua; Chen, Xiaofeng; Ma, Shihua; Wu, Xiumei; Yang, Wenxing; Zhang, Weifeng; Li, Xiao

    2018-04-01

    We demonstrate the capability of terahertz (THz) time-domain spectroscopy (TDS) to quantify glucose level in ex vivo freshly diabetic's blood. By investigating the THz spectra of different human blood, we find out THz absorption coefficients reflect a high sensitivity to the glucose level in blood. With a quantitative analysis of 70 patients, we demonstrate that the THz absorption coefficients and the blood glucose levels perform a linear relationship. A comparative experiment between THz measurement and glucometers is also conducted with another 20 blood samples, and the results confirm that the relative error is as less as 15%. Our ex vivo human blood study indicates that THz technique has great potential application to diagnose blood glucose level in clinical practice.

  3. In vitro terahertz spectroscopy of gelatin-embedded human brain tumors: a pilot study

    Science.gov (United States)

    Chernomyrdin, N. V.; Gavdush, A. A.; Beshplav, S.-I. T.; Malakhov, K. M.; Kucheryavenko, A. S.; Katyba, G. M.; Dolganova, I. N.; Goryaynov, S. A.; Karasik, V. E.; Spektor, I. E.; Kurlov, V. N.; Yurchenko, S. O.; Komandin, G. A.; Potapov, A. A.; Tuchin, V. V.; Zaytsev, K. I.

    2018-04-01

    We have performed the in vitro terahertz (THz) spectroscopy of human brain tumors. In order to fix tissues for the THz measurements, we have applied the gelatin embedding. It allows for preserving tissues from hydration/dehydration and sustaining their THz response similar to that of the freshly-excised tissues for a long time after resection. We have assembled an experimental setup for the reflection-mode measurements of human brain tissues based on the THz pulsed spectrometer. We have used this setup to study in vitro the refractive index and the amplitude absorption coefficient of 2 samples of malignant glioma (grade IV), 1 sample of meningioma (grade I), and samples of intact tissues. We have observed significant differences between the THz responses of normal and pathological tissues of the brain. The results of this paper highlight the potential of the THz technology in the intraoperative neurodiagnosis of tumors relying on the endogenous labels of tumorous tissues.

  4. Microscopic theory of linear and nonlinear terahertz spectroscopy of semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Steiner, Johannes

    2008-12-09

    This Thesis presents a fully microscopic theory to describe terahertz (THz)-induced processes in optically-excited semiconductors. The formation process of excitons and other quasi-particles after optical excitation has been studied in great detail for a variety of conditions. Here, the formation process is not modelled but a realistic initial many-body state is assumed. In particular, the linear THz response is reviewed and it is demonstrated that correlated quasi-particles such as excitons and plasmons can be unambiguously detected via THz spectroscopy. The focus of the investigations, however, is on situations where the optically-excited many-body state is excited by intense THz fields. While weak pulses detect the many-body state, strong THz pulses control and manipulate the quasi-particles in a way that is not accessible via conventional techniques. The nonlinear THz dynamics of exciton populations is especially interesting because similarities and differences to optics with atomic systems can be studied. (orig.)

  5. Far infrared and terahertz spectroscopy of ferroelectric soft modes in thin films: a review

    Czech Academy of Sciences Publication Activity Database

    Petzelt, Jan; Kamba, Stanislav

    2016-01-01

    Roč. 503, č. 1 (2016), s. 19-44 ISSN 0015-0193 R&D Projects: GA ČR GA15-08389S Institutional support: RVO:68378271 Keywords : soft mode * central mode * ferroelectric thin film * terahertz spectroscopy * far-infrared spectroscopy Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.551, year: 2016

  6. Picosecond charge transport in rutile at high carrier densities studiedby transient terahertz spectroscopy

    Czech Academy of Sciences Publication Activity Database

    Zajac, Vít; Němec, Hynek; Kužel, Petr

    2016-01-01

    Roč. 94, č. 11 (2016), 1-9, č. článku 115206. ISSN 1098-0121 R&D Projects: GA ČR GA13-12386S Institutional support: RVO:68378271 Keywords : terahertz spectroscopy * charge transport * TiO 2 * rutile * ultrafast spectroscopy Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.736, year: 2014

  7. Quantitative terahertz time-domain spectroscopy and analysis in chemistry and biology

    DEFF Research Database (Denmark)

    Jepsen, Peter Uhd

    2005-01-01

    I will describe how Terahertz Time-Domain Spectroscopy (THz-TDS) can be used for quantitative, broadband spectroscopy in the far-infrared spectral region. Thz-TDS is sensitive to long-range, non-covalent interactions in the condensed phase, for instance intermolecular hydrogen bonding in molecula...

  8. Laminated helmet materials characterization by terahertz kinetics spectroscopy

    Science.gov (United States)

    Rahman, Anis; Rahman, Aunik K.

    2015-05-01

    High speed acquisition of reflected terahertz energy constitutes a kinetics spectrum that is an effective tool for layered materials' deformation characterization under ballistic impact. Here we describe utilizing the kinetics spectrum for quantifying a deformation event due to impact in material used for Soldier's helmet. The same technique may be utilized for real-time assessment of trauma by measuring the helmet wore by athletes. The deformation of a laminated material (e.g., a helmet) is dependent on the nature of impact and projectile; thus can uniquely characterize the impact condition leading to a diagnostic procedure based on the energy received by an athlete during an impact. We outline the calibration process for a given material under ballistic impact and then utilize the calibration for extracting physical parameters from the measured kinetics spectrum. Measured kinetics spectra are used to outline the method and rationale for extending the concept to a diagnosis tool. In particular, captured kinetics spectra from multilayered plates subjected to ballistic hit under experimental conditions by high speed digital acquisition system. An algorithm was devised to extract deformation and deformation velocity from which the energy received on the skull was estimated via laws of nonrelativistic motion. This energy is assumed to be related to actual injury conditions, thus forming a basis for determining whether the hit would cause concussion, trauma, or stigma. Such quantification may be used for diagnosing a Soldier's trauma condition in the field or that of an athlete's.

  9. Contactless graphene conductance measurements: the effect of device fabrication on terahertz time-domain spectroscopy

    DEFF Research Database (Denmark)

    Mackenzie, David; Buron, Jonas Christian Due; Bøggild, Peter

    2016-01-01

    We perform contactless full-wafer maps of the electrical conductance of a 4-inch wafer of single-layer CVD graphene using terahertz time-domain spectroscopy both before and after deposition of metal contacts and fabrication of devices via laser ablation. We find that there is no significant change...... in the measured conductance of graphene before and after device fabrication. We also show that precise terahertz time-domain spectroscopy can be performed when the beam spot is at sufficient distance (>1.2 mm) from metal contacts....

  10. Mobile charge generation dynamics in P3HT: PCBM observed by time-resolved terahertz spectroscopy

    DEFF Research Database (Denmark)

    Cooke, D. G.; Krebs, Frederik C; Jepsen, Peter Uhd

    2012-01-01

    Ultra-broadband time-resolved terahertz spectroscopy is used to examine the sub-ps conductivity dynamics of a conjugated polymer bulk heterojunction film P3HT:PCBM. We directly observe mobile charge generation dynamics on a sub-100 fs time scale.......Ultra-broadband time-resolved terahertz spectroscopy is used to examine the sub-ps conductivity dynamics of a conjugated polymer bulk heterojunction film P3HT:PCBM. We directly observe mobile charge generation dynamics on a sub-100 fs time scale....

  11. Non-destructive evaluation of the hidden voids in integrated circuit packages using terahertz time-domain spectroscopy

    International Nuclear Information System (INIS)

    Park, Sung-Hyeon; Kim, Hak-Sung; Jang, Jin-Wook

    2015-01-01

    In this work, a terahertz time-domain spectroscopy (THz-TDS) imaging technique was used as a non-destructive inspection method for detecting voids in integrated circuit (IC) packages. Transmission and reflection modes, with an angle of incidence of 30°, were used to detect voids in IC packages. The locations of the detected voids in the IC packages could be calculated by analyzing THz waveforms. Finally, voids that are positioned at the different interfaces in the IC package samples could be successfully detected and imaged. Therefore, this THz-TDS imaging technique is expected to be a promising technique for non-destructive evaluation of IC packages. (paper)

  12. Terahertz spectroscopy and imaging for cultural heritage management: state of art and perspectives

    Science.gov (United States)

    Catapano, Ilaria; Soldovieri, Francesco

    2014-05-01

    molecular stability of the exposed objects and humans. Recently, the interest on THz technology is also growing up thanks to the development of flexible and compact commercial systems having source and detector probes coupled by means of optical fiber cables and that do not require complex optical alignments. These features allow us to reconfigure the measurement configuration easily; thus transmission, normal reflection and oblique reflection data can be collected according to the constrains and objective of the survey to be performed. Moreover, they open the way to on field applications. An example of last generation THz systems is the Fiber-Coupled Terahertz Time Domain System (FICO) marketed by Z-Omega and available at the Institute of Electromagnetic Sensing of the Environment. Such a system is designed to perform both transmission and reflection spectroscopy and imaging measurements in the range from 60GHz to 3THz; with a waveform acquisition speed up to 500Hz. A review of the literature assessing potentialities and open challenges of THz spectroscopy and imaging in the frame of cultural heritage preservation will be provided at the conferences, with a specific focus on the diagnostic capabilities of last generation systems. REFERENCES [1] K. Fukunaga, I. Hosako, Innovative non-invasive analysis techniques for cultural heritage using terahertz technology, C. R. Physique, vol. 11, pp.519-526, 2010. [2] G.Fillippidis, M. Massaouti, A. Selimis, E.J. Gualda, J.M. Manceau, S. Tzortzakis, Nonlinear imaging and THz diagnostic tools in the service of Cultural Heritage, Appl. Phys. A, vol.106, pp.257-263, 2012.

  13. A novel analytical method for pharmaceutical polymorphs by terahertz spectroscopy and the optimization of crystal form at the discovery stage.

    Science.gov (United States)

    Ikeda, Yukihiro; Ishihara, Yoko; Moriwaki, Toshiya; Kato, Eiji; Terada, Katsuhide

    2010-01-01

    A novel analytical method for the determination of pharmaceutical polymorphs was developed using terahertz spectroscopy. It was found out that each polymorph of a substance showed a specific terahertz absorption spectrum. In particular, analysis of the second derivative spectrum was enormously beneficial in the discrimination of closely related polymorphs that were difficult to discern by powder X-ray diffractometry. Crystal forms that were obtained by crystallization from various solvents and stored under various conditions were specifically characterized by the second derivative of each terahertz spectrum. Fractional polymorphic transformation for substances stored under stressed conditions was also identified by terahertz spectroscopy during solid-state stability test, but could not be detected by powder X-ray diffractometry. Since polymorphs could be characterized clearly by terahertz spectroscopy, further physicochemical studies could be conducted in a timely manner. The development form of compound examined was determined by the results of comprehensive physicochemical studies that included thermodynamic relationships, as well as chemical and physicochemical stability. In conclusion, terahertz spectroscopy, which has unique power in the elucidation of molecular interaction within a crystal lattice, can play more important role in physicochemical research. Terahertz spectroscopy has a great potential as a tool for polymorphic determination, particularly since the second derivative of the terahertz spectrum possesses high sensitivity for pharmaceutical polymorphs.

  14. Linearity of Air-Biased Coherent Detection for Terahertz Time-Domain Spectroscopy

    DEFF Research Database (Denmark)

    Wang, Tianwu; Iwaszczuk, Krzysztof; Wrisberg, Emil Astrup

    2016-01-01

    The performance of air-biased coherent detection (ABCD) in a broadband two-color laser-induced air plasma system for terahertz time-domain spectroscopy (THz-TDS) has been investigated. Fundamental parameters of the ABCD detection, including signal-to-noise ratio (SNR), dynamic range (DR), and lin...

  15. Charge transport in anodic TiO.sub.2./sub. nanotubes studied by terahertz spectroscopy

    Czech Academy of Sciences Publication Activity Database

    Krbal, M.; Kuchařík, Jiří; Sopha, H.; Němec, Hynek; Macák, J. M.

    2016-01-01

    Roč. 10, č. 9 (2016), s. 691-695 ISSN 1862-6254 R&D Projects: GA ČR GA13-12386S Institutional support: RVO:68378271 Keywords : terahertz spectroscopy * charge transport * TiO2 nanotubes Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.032, year: 2016

  16. Finite-difference time-domain analysis of time-resolved terahertz spectroscopy experiments

    DEFF Research Database (Denmark)

    Larsen, Casper; Cooke, David G.; Jepsen, Peter Uhd

    2011-01-01

    In this paper we report on the numerical analysis of a time-resolved terahertz (THz) spectroscopy experiment using a modified finite-difference time-domain method. Using this method, we show that ultrafast carrier dynamics can be extracted with a time resolution smaller than the duration of the T...

  17. Study of the ferroelectric phase transition in germanium telluride using time-domain terahertz spectroscopy

    Czech Academy of Sciences Publication Activity Database

    Kadlec, Filip; Kadlec, Christelle; Kužel, Petr; Petzelt, Jan

    2011-01-01

    Roč. 84, č. 20 (2011), 205209/1-205209/8 ISSN 1098-0121 R&D Projects: GA ČR GC202/09/J045 Institutional research plan: CEZ:AV0Z10100520 Keywords : terahertz spectroscopy * phase transition * semiconductor Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.691, year: 2011

  18. TeraHertz Time Domain Spectroscopy of Astrophysical Analog Materials

    Science.gov (United States)

    Blake, Geoffrey

    The section of the electromagnetic spectrum extending roughly from wavelengths of 3 millimeters to 30 microns is commonly known as the far-infrared or TeraHertz (THz) region. It contains the great majority of the photons emitted by the universe, and THz observations of molecules and dust are able penetrate deeply into molecular clouds, thus revealing the full history of star and planet formation. Accordingly, the successful deployments of the Herschel and SOFIA observatories, and the emerging capabilities of ALMA, are both revolutionizing our understanding of THz astrophysics and placing stringent demands on the generation of accurate laboratory data on the relevant gas phase and solid state materials detected. With APRA support, we have constructed a combined high bandwidth and high spectral resolution femtosecond THz Time Domain Spectroscopy (THz TDS) system and an FT-IR spectrometer, and coupled these instruments to a high vacuum chamber and cryostat and to gas phase cells including a molecular beam system. We have investigated solid materials from room temperature to 10 K, and can examine both refractory matter such as silicates and molecular ices. For the latter, we have demonstrated that the THz bands observed are uniquely sensitive to both the molecular structure of the ice and its thermal history, and thus that THz observations can provide novel insight into the dominant condensable materials in dense, cold regions. In the gas phase we can record doppler-limited data over at least a decade in bandwidth. While quite capable, the high vacuum cryostat can only study thick samples, especially ices, due to the fairly rapid adsorption of gases onto surfaces at low temperature under such conditions. It is therefore not possible to examine highly layered/structured samples or reactive species. We therefore propose here to upgrade the chamber/cryostat to ultrahigh vacuum, and implement additional sample preparation and characterization tools. With such modifications

  19. Time-resolved single-shot terahertz time-domain spectroscopy for ultrafast irreversible processes

    Science.gov (United States)

    Zhai, Zhao-Hui; Zhong, Sen-Cheng; Li, Jun; Zhu, Li-Guo; Meng, Kun; Li, Jiang; Liu, Qiao; Peng, Qi-Xian; Li, Ze-Ren; Zhao, Jian-Heng

    2016-09-01

    Pulsed terahertz spectroscopy is suitable for spectroscopic diagnostics of ultrafast events. However, the study of irreversible or single shot ultrafast events requires ability to record transient properties at multiple time delays, i.e., time resolved at single shot level, which is not available currently. Here by angular multiplexing use of femtosecond laser pulses, we developed and demonstrated a time resolved, transient terahertz time domain spectroscopy technique, where burst mode THz pulses were generated and then detected in a single shot measurement manner. The burst mode THz pulses contain 2 sub-THz pulses, and the time gap between them is adjustable up to 1 ns with picosecond accuracy, thus it can be used to probe the single shot event at two different time delays. The system can detect the sub-THz pulses at 0.1 THz-2.5 THz range with signal to noise ratio (SNR) of ˜400 and spectrum resolution of 0.05 THz. System design was described here, and optimizations of single shot measurement of THz pulses were discussed in detail. Methods to improve SNR were also discussed in detail. A system application was demonstrated where pulsed THz signals at different time delays of the ultrafast process were successfully acquired within single shot measurement. This time resolved transient terahertz time domain spectroscopy technique provides a new diagnostic tool for irreversible or single shot ultrafast events where dynamic information can be extracted at terahertz range within one-shot experiment.

  20. The application of terahertz spectroscopy and imaging in biomedicine

    International Nuclear Information System (INIS)

    Liu Shangjian; Yu Fei; Li Kai; Zhou Jing

    2013-01-01

    Terahertz (THz) science and technology is gaining increasing attention in the biomedical field. Compared with traditional medical diagnosis methods using infrared radiation, nuclear magnetic resonance, X-rays or ultrasound, THz radiation has low energy, high spatial resolution, a broad spectral range, and is a reliable means of imaging for the human body. Terahertz waves have strong penetration and high fingerprint specificity, so they can play an important role in drug detection and identification. This paper reviews the special techniques based on conventional THz time-domain setups in disease detection and drug identification. With regard to the biomedical fields, we focus on the application of THz radiation in studies of skin tissue, gene expression, cells, cancer imaging, the quantitative analysis of drugs, and so on. We also present an overview of the future challenges and prospects of THz research in medicine. (authors)

  1. Nondestructive Evaluation of Aircraft Composites Using Terahertz Time Domain Spectroscopy

    Science.gov (United States)

    2008-12-10

    silicon or silicon dioxide in polypropylene . 50 THz NDE is also being proposed as a method of inspecting the adhesive bond- line of space...weave the overlapping pattern used in the composite. The polyimide resin is added and permeates throughout the individual glass fiber strands. The...dx.doi.org/10.1117/12.590301 65. Rutz, F., Hasek, T., Koch, M., Richter, H., Ewert, U. (2006). Terahertz birefringence of liquid crystal polymers

  2. Terahertz time-domain spectroscopy of edible oils

    OpenAIRE

    Dinovitser, Alex; Valchev, Dimitar G.; Abbott, Derek

    2017-01-01

    Chemical degradation of edible oils has been studied using conventional spectroscopic methods spanning the spectrum from ultraviolet to mid-IR. However, the possibility of morphological changes of oil molecules that can be detected at terahertz frequencies is beginning to receive some attention. Furthermore, the rapidly decreasing cost of this technology and its capability for convenient, in situ measurement of material properties, raises the possibility of monitoring oil during cooking and p...

  3. Emulation and design of terahertz reflection-mode confocal scanning microscopy based on virtual pinhole

    Science.gov (United States)

    Yang, Yong-fa; Li, Qi

    2014-12-01

    In the practical application of terahertz reflection-mode confocal scanning microscopy, the size of detector pinhole is an important factor that determines the performance of spatial resolution characteristic of the microscopic system. However, the use of physical pinhole brings some inconvenience to the experiment and the adjustment error has a great influence on the experiment result. Through reasonably selecting the parameter of matrix detector virtual pinhole (VPH), it can efficiently approximate the physical pinhole. By using this approach, the difficulty of experimental calibration is reduced significantly. In this article, an imaging scheme of terahertz reflection-mode confocal scanning microscopy that is based on the matrix detector VPH is put forward. The influence of detector pinhole size on the axial resolution of confocal scanning microscopy is emulated and analyzed. Then, the parameter of VPH is emulated when the best axial imaging performance is reached.

  4. Fiber MOPA based tunable source for terahertz spectroscopy

    International Nuclear Information System (INIS)

    Malinowski, A; Lin, D; Alam, S U; Zhang, Z; Ibsen, M; Richardson, D J; Young, J; Wright, P; Ozanyan, K; Stringer, M; Miles, R E

    2012-01-01

    We have developed a terahertz spectrometer based on difference frequency generation of beams from an ytterbium fiber master oscillator power amplifier (MOPA) system. The spectrometer has a resolution of ∼ 2 GHz. It can be tuned rapidly over several hundred GHz, and a wider frequency range can be covered (0.7–2.5 THz demonstrated) by swapping in alternate seed lasers and adjusting the alignment of the beams into the difference frequency generation (DFG) crystal. The system was constructed entirely from commercially available fiber and fiber components. We present some demonstration data on water vapor absorption lines

  5. Reflection-type electromagnetically induced transparency analogue in terahertz metamaterials

    International Nuclear Information System (INIS)

    Ding Chun-Feng; Zhang Ya-Ting; Yao Jian-Quan; Xu De-Gang; Zhang Gui-Zhong; Sun Chong-Ling

    2014-01-01

    A reflection-type electromagnetically induced transparency (EIT) metamaterial is proposed, which is composed of a dielectric spacer sandwiched with metallic patterns and metallic plane. Experimental results of THz time domain spectrum (THz-TDS) exhibit a typical reflection of EIT at 0.865 THz, which are in excellent agreement with the full-wave simulations. A multi-reflection theory is adopted to analyze the physical mechanism of the reflection-type EIT, showing that the reflection-type EIT is a superposition of multiple reflection of the transmission EIT. Such a reflection-type EIT provides many applications based on the EIT effect, such as slow light devices and nonlinear elements. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

  6. Insights into the charge carrier terahertz mobility in polyfluorenes from large-scale atomistic simulations and time-resolved terahertz spectroscopy

    Czech Academy of Sciences Publication Activity Database

    Vukmirović, N.; Ponseca, C.S.; Němec, Hynek; Yartsev, A.; Sundström, V.

    2012-01-01

    Roč. 116, č. 37 (2012), s. 19665-1972 ISSN 1932-7447 Institutional research plan: CEZ:AV0Z10100520 Keywords : charge carrier mobility * time-resolved terahertz spectroscopy * multiscale atomistic calculations Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 4.814, year: 2012

  7. Characterization of Temperature Induced Phase Transitions in the Five Polymorphic Forms of Sulfathia-zole by Terahertz Pulsed Spectroscopy and Differential Scanning Calorimetry

    DEFF Research Database (Denmark)

    Zeitler, J. Axel; Newnham, David A.; Taday, Philip F.

    2006-01-01

    The far-infrared properties of all five described polymorphic forms of the drug sulfathiazole have been studied by terahertz pulsed spectroscopy and low frequency Raman spectroscopy. The spectra of the different polymorphs are distinctly different. Terahertz pulsed spectroscopy proves to be a rap...

  8. Departure from BCS response in photoexcited superconducting NbN films observed by terahertz spectroscopy

    Czech Academy of Sciences Publication Activity Database

    Šindler, Michal; Kadlec, Christelle; Kužel, Petr; Il'in, K.; Siegel, M.; Němec, Hynek

    2018-01-01

    Roč. 97, č. 5 (2018), s. 1-5, č. článku 054507. ISSN 2469-9950 R&D Projects: GA ČR GA17-04412S Institutional support: RVO:68378271 Keywords : terahertz spectroscopy * NbN thin films * superconductors Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.) Impact factor: 3.836, year: 2016

  9. Broadband terahertz spectroscopy: principles, fundamental research and potential for industrial applications

    International Nuclear Information System (INIS)

    Zouaghi, W; Thomson, M D; Rabia, K; Hahn, R; Blank, V; Roskos, H G

    2013-01-01

    Terahertz radiation (also called T-rays) can be employed for spectroscopy and imaging, from the laboratory to industrial applications. In this paper we give an overview of how broadband optoelectronic THz techniques (i.e. using optical lasers to achieve THz generation and detection) can be implemented, and give examples of their unique use in solid-state physics, and in biological and industrial applications. (paper)

  10. Terahertz spectroscopy of three-dimensional photonic band-gap crystals

    International Nuclear Information System (INIS)

    Oezbay, E.; Michel, E.; Tuttle, G.; Biswas, R.; Ho, K.M.; Bostak, J.; Bloom, D.M.

    1994-01-01

    We have fabricated and built three-dimensional photonic band-gap crystals with band-gap frequencies larger than 500 GHz. We built the crystals by stacking micromachined (110) silicon wafers. The transmission and dispersion characteristics of the structures were measured by an all-electronic terahertz spectroscopy setup. The experimental results were in good agreement with theoretical calculations. To our knowledge, our new crystal has the highest reported photonic band-gap frequency

  11. Ultrafast conductivity in a low-band-gap polyphenylene and fullerene blend studied by terahertz spectroscopy

    Czech Academy of Sciences Publication Activity Database

    Němec, Hynek; Nienhuys, H.-K.; Perzon, E.; Zhang, F.; Inganäs, O.; Kužel, Petr; Sundström, V.

    2009-01-01

    Roč. 79, č. 24 (2009), 245326/1-245326/7 ISSN 1098-0121 R&D Projects: GA ČR(CZ) GP202/09/P099; GA MŠk LC512; GA ČR(CZ) GA202/06/0286 Institutional research plan: CEZ:AV0Z10100520 Keywords : time-resolved terahertz spectroscopy * ultrafast conductivity * polymer * solar-cell material Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.475, year: 2009

  12. Charge transport in nanostructured materials for solar energy conversion studied by time-resolved terahertz spectroscopy

    Czech Academy of Sciences Publication Activity Database

    Němec, Hynek; Kužel, Petr; Sundström, V.

    2010-01-01

    Roč. 215, 2-3 (2010), s. 123-139 ISSN 1010-6030 R&D Projects: GA ČR(CZ) GP202/09/P099; GA AV ČR(CZ) IAA100100902; GA MŠk LC512 Institutional research plan: CEZ:AV0Z10100520 Keywords : time-resolved terahertz spectroscopy * ultrafast dynamics * bulk heterojunction * semiconductor nanostructures * transport * mobility Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.243, year: 2010

  13. Detection of Genetically Modified Sugarcane by Using Terahertz Spectroscopy and Chemometrics

    Science.gov (United States)

    Liu, J.; Xie, H.; Zha, B.; Ding, W.; Luo, J.; Hu, C.

    2018-03-01

    A methodology is proposed to identify genetically modified sugarcane from non-genetically modified sugarcane by using terahertz spectroscopy and chemometrics techniques, including linear discriminant analysis (LDA), support vector machine-discriminant analysis (SVM-DA), and partial least squares-discriminant analysis (PLS-DA). The classification rate of the above mentioned methods is compared, and different types of preprocessing are considered. According to the experimental results, the best option is PLS-DA, with an identification rate of 98%. The results indicated that THz spectroscopy and chemometrics techniques are a powerful tool to identify genetically modified and non-genetically modified sugarcane.

  14. Consistency-dependent optical properties of lubricating grease studied by terahertz spectroscopy

    International Nuclear Information System (INIS)

    Tian Lu; Zhao Kun; Zhou Qing-Li; Shi Yu-Lei; Zhao Dong-Mei; Zhang Cun-Lin; Zhao Song-Qing; Zhao Hui; Bao Ri-Ma; Zhu Shou-Ming; Miao Qing

    2011-01-01

    The optical properties of four kinds of lubricating greases (urea, lithium, extreme pressure lithium, molybdenum disulfide lithium greases) with different NLGL (National Lubricant Grease Institute of America) numbers were investigated using terahertz time-domain spectroscopy. Greases with different NLGL grades have unique spectral features in the terahertz range. Comparison of the experimental data with predictions based on Lorentz—Lorenz theory exhibited that the refractive indices of each kind of lubricating grease were dependent on the their consistency. In addition, molybdenum disulfide (MoS 2 ) as a libricant additive shows strong absorption from 0.2 to 1.4 THz, leading to higher absorption of MoS 2 -lithium grease than that of lithium grease. (general)

  15. Pixel Statistical Analysis of Diabetic vs. Non-diabetic Foot-Sole Spectral Terahertz Reflection Images

    Science.gov (United States)

    Hernandez-Cardoso, G. G.; Alfaro-Gomez, M.; Rojas-Landeros, S. C.; Salas-Gutierrez, I.; Castro-Camus, E.

    2018-03-01

    In this article, we present a series of hydration mapping images of the foot soles of diabetic and non-diabetic subjects measured by terahertz reflectance. In addition to the hydration images, we present a series of RYG-color-coded (red yellow green) images where pixels are assigned one of the three colors in order to easily identify areas in risk of ulceration. We also present the statistics of the number of pixels with each color as a potential quantitative indicator for diabetic foot-syndrome deterioration.

  16. Graphene hyperlens for terahertz radiation

    DEFF Research Database (Denmark)

    Andryieuski, Andrei; Chigrin, D.; Novitsky, Andrey

    2012-01-01

    We propose the structured graphene terahertz hyperlens that allows overcoming natural diffraction limit and resolving subwavelength features. The proposed hyperlens can have applications in terahertz spectroscopy and imaging.......We propose the structured graphene terahertz hyperlens that allows overcoming natural diffraction limit and resolving subwavelength features. The proposed hyperlens can have applications in terahertz spectroscopy and imaging....

  17. Investigating the use of terahertz pulsed time domain reflection imaging for the study of fabric layers of an Egyptian mummy

    Science.gov (United States)

    Fukunaga, K.; Cortes, E.; Cosentino, A.; Stã¼nkel, I.; Leona, M.; Duling, N.; Mininberg, D. T.

    2011-08-01

    This paper reports the first use of terahertz time domain reflection imaging involving textiles on part of a complete human mummy, still in original wrapping. X-ray technique has been used extensively to investigate anatomical features, since X-ray pass through the wrapping. Terahertz waves, on the other hand, can penetrate into non-metallic materials and its reflection depends on the refractive index of materials at the interface, such as textiles and the air. The mummy of Kharushere (ca. 945-712 B.C.) was examined by using Terahertz time domain reflection imaging in the Egyptian galleries of The Metropolitan Museum of Art. Experimental results suggest that the Terahetz imaging is a promising technique for probing the fabric layers surrounding Egyptian mummies, although it is still very limited in its current state. In the future it could become a useful complement to CT scanning when materials with low radiographic density and contrast are being investigated

  18. Spectrally interleaved, comb-mode-resolved spectroscopy using swept dual terahertz combs

    Science.gov (United States)

    Hsieh, Yi-Da; Iyonaga, Yuki; Sakaguchi, Yoshiyuki; Yokoyama, Shuko; Inaba, Hajime; Minoshima, Kaoru; Hindle, Francis; Araki, Tsutomu; Yasui, Takeshi

    2014-01-01

    Optical frequency combs are innovative tools for broadband spectroscopy because a series of comb modes can serve as frequency markers that are traceable to a microwave frequency standard. However, a mode distribution that is too discrete limits the spectral sampling interval to the mode frequency spacing even though individual mode linewidth is sufficiently narrow. Here, using a combination of a spectral interleaving and dual-comb spectroscopy in the terahertz (THz) region, we achieved a spectral sampling interval equal to the mode linewidth rather than the mode spacing. The spectrally interleaved THz comb was realized by sweeping the laser repetition frequency and interleaving additional frequency marks. In low-pressure gas spectroscopy, we achieved an improved spectral sampling density of 2.5 MHz and enhanced spectral accuracy of 8.39 × 10-7 in the THz region. The proposed method is a powerful tool for simultaneously achieving high resolution, high accuracy, and broad spectral coverage in THz spectroscopy.

  19. Spectrally interleaved, comb-mode-resolved spectroscopy using swept dual terahertz combs.

    Science.gov (United States)

    Hsieh, Yi-Da; Iyonaga, Yuki; Sakaguchi, Yoshiyuki; Yokoyama, Shuko; Inaba, Hajime; Minoshima, Kaoru; Hindle, Francis; Araki, Tsutomu; Yasui, Takeshi

    2014-01-22

    Optical frequency combs are innovative tools for broadband spectroscopy because a series of comb modes can serve as frequency markers that are traceable to a microwave frequency standard. However, a mode distribution that is too discrete limits the spectral sampling interval to the mode frequency spacing even though individual mode linewidth is sufficiently narrow. Here, using a combination of a spectral interleaving and dual-comb spectroscopy in the terahertz (THz) region, we achieved a spectral sampling interval equal to the mode linewidth rather than the mode spacing. The spectrally interleaved THz comb was realized by sweeping the laser repetition frequency and interleaving additional frequency marks. In low-pressure gas spectroscopy, we achieved an improved spectral sampling density of 2.5 MHz and enhanced spectral accuracy of 8.39 × 10(-7) in the THz region. The proposed method is a powerful tool for simultaneously achieving high resolution, high accuracy, and broad spectral coverage in THz spectroscopy.

  20. Thermal denaturation of protein studied by terahertz time-domain spectroscopy

    Science.gov (United States)

    Fu, Xiuhua; Li, Xiangjun; Liu, Jianjun; Du, Yong; Hong, Zhi

    2012-12-01

    In this study, the absorption spectra of native or thermal protein were measured in 0.2-1.4THz using terahertz time-domain spectroscopy (THz-TDS) system at room temperature, their absorption spectra and the refractive spectra were obtained. Experimental results indicate that protein both has strong absorption but their characteristics were not distinct in the THz region, and the absorption decreased during thermal denatured state. In order to prove protein had been denatured, we used Differential scanning calorimeter (DSC) measured their denatured temperature, from their DSC heating traces, collagen Td=101℃, Bovine serum albumin Td=97℃. While we also combined the Fourier transform infrared spectrometer (FTIR) to investigate their secondary and tertiary structure before and after denatuation, but the results did not have the distinct changes. We turned the absorption spectra and the refractive spectra to the dielectric spectra, and used the one-stage Debye model simulated the terahertz dielectric spectra of protein before and after denaturation. This research proved that the terahertz spectrum technology is feasible in testing protein that were affected by temperature or other factors which can provide theoretical foundation in the further study about the THz spectrum of protein and peptide temperature stability.

  1. Graphene based terahertz phase modulators

    Science.gov (United States)

    Kakenov, N.; Ergoktas, M. S.; Balci, O.; Kocabas, C.

    2018-07-01

    Electrical control of amplitude and phase of terahertz radiation (THz) is the key technological challenge for high resolution and noninvasive THz imaging. The lack of active materials and devices hinders the realization of these imaging systems. Here, we demonstrate an efficient terahertz phase and amplitude modulation using electrically tunable graphene devices. Our device structure consists of electrolyte-gated graphene placed at quarter wavelength distance from a reflecting metallic surface. In this geometry, graphene operates as a tunable impedance surface which yields electrically controlled reflection phase. Terahertz time domain reflection spectroscopy reveals the voltage controlled phase modulation of π and the reflection modulation of 50 dB. To show the promises of our approach, we demonstrate a multipixel phase modulator array which operates as a gradient impedance surface.

  2. Measurement of Absorption Coefficient of Paraformaldehyde and Metaldehyde with Terahertz Spectroscopy

    Science.gov (United States)

    Zhang, J.; Xia, T.; Chen, Q.; Sun, Q.; Deng, Y.; Wang, C.

    2018-03-01

    The characteristic absorption spectra of paraformaldehyde and metaldehyde in the terahertz frequency region are obtained by terahertz time-domain spectroscopy (THz-TDS). In order to reduce the absorption of terahertz (THz) wave by water vapor in the air and the background noise, the measurement system was filled with dry air and the measurements were conducted at the temperature of 24°C. Meanwhile, the humidity was controlled within 10% RH. The THz frequency domain spectra of samples and their references from 0 to 2.5 THz were analyzed via Fourier transform. The refractive index and absorption coefficients of the two aldehydes were calculated by the model formulas. From 0.1 to 2.5 THz, there appear two weak absorption peaks at 1.20 and 1.66 THz in the absorption spectra of paraformaldehyde. Only one distinct absorption peak emerges at 1.83 THz for metaldehyde. There are significant differences between the terahertz absorption coefficients of paraformaldehyde and metaldehyde, which can be used as "fingerprints" to identify these substances. Furthermore, the relationship between the average absorption coefficients and mass concentrations was investigated and the average absorption coefficient-mass concentration diagrams of paraformaldehyde and metaldehyde were shown. For paraformaldehyde, there is a linear relationship between the average absorption coefficient and the natural logarithm of mass concentration. For metaldehyde, there exists a simpler linear relationship between the average absorption coefficient and the mass concentration. Because of the characteristics of THz absorption of paraformaldehyde and metaldehyde, the THz-TDS can be applied to the qualitative and quantitative detection of the two aldehydes to reduce the unpredictable hazards due to these substances.

  3. Mobile Charge Generation Dynamics in P3HT:PCBM Observed by Time-Resolved Terahertz Spectroscopy

    DEFF Research Database (Denmark)

    Cooke, D. G.; Krebs, Frederik C; Jepsen, Peter Uhd

    2012-01-01

    Ultra-broadband time-resolved terahertz spectroscopy is used to examine the sub-ps conductivity dynamics of a conjugated polymer bulk heterojunction film P3HT:PCBM. We directly observe mobile charge generation dynamics on a sub-100 fs time scale.......Ultra-broadband time-resolved terahertz spectroscopy is used to examine the sub-ps conductivity dynamics of a conjugated polymer bulk heterojunction film P3HT:PCBM. We directly observe mobile charge generation dynamics on a sub-100 fs time scale....

  4. Exploiting total internal reflection geometry for efficient optical modulation of terahertz light

    Directory of Open Access Journals (Sweden)

    Xudong Liu

    2016-10-01

    Full Text Available Efficient methods to modulate terahertz (THz light are essential for realizing rapid THz imaging and communication applications. Here we report a novel THz modulator which utilizes the evanescent wave in a total internal reflection setup coupled with a conductive interface to enhance the attenuation efficiency of THz light. This approach makes it possible to achieve close to 100% modulation with a small interface conductivity of 12 mS. The frequency dependence of this technique is linked to the optical properties of the materials: a material with close to frequency independent conductivity that is also controllable will result in an achromatic modulation response, and the device performance can be optimized further by tuning the internal reflection angle. In this work, we focus on applying the technique in the terahertz frequency range. Using an LED array with a pump intensity of 475 mW/cm2 to produce carriers in a silicon wafer, we have achieved a modulation depth of up to 99.9% in a broad frequency range of 0.1 THz–0.8 THz. The required pumping power for the generation of the required free carriers is low because the sheet conductivity needed is far less than required for traditional transmission techniques. Consequently, the device can be modulated by an LED making it a very practical, low cost, and scalable solution for THz modulation.

  5. High resolution terahertz spectroscopy of a whispering gallery mode bubble resonator using Hilbert analysis.

    Science.gov (United States)

    Vogt, Dominik Walter; Leonhardt, Rainer

    2017-07-10

    We report on data processing for continuous wave (CW) terahertz (THz) spectroscopy measurements based on a Hilbert spectral analysis to achieve MHz resolution. As an example we investigate the spectral properties of a whispering gallery mode (WGM) THz bubble resonator at critical coupling. The experimental verification clearly demonstrates the significant advantages in relative frequency resolution and required acquisition time of the proposed method over the traditional data analysis. An effective frequency resolution, only limited by the precision and stability of the laser beat signal, can be achieved without complex extensions to a standard commercially available CW THz spectrometer.

  6. Measurement of electron paramagnetic resonance using terahertz time-domain spectroscopy.

    Science.gov (United States)

    Kozuki, Kohei; Nagashima, Takeshi; Hangyo, Masanori

    2011-12-05

    We present a frequency-domain electron spin resonance (ESR) measurement system using terahertz time-domain spectroscopy. A crossed polarizer technique is utilized to increase the sensitivity in detecting weak ESR signals of paramagnets caused by magnetic dipole transitions between magnetic sublevels. We demonstrate the measurements of ESR signal of paramagnetic copper(II) sulfate pentahydrate with uniaxial anisotropy of the g-factor under magnetic fields up to 10 T. The lineshape of the obtained ESR signals agrees well with the theoretical predictions for a powder sample with the uniaxial anisotropy.

  7. Time-resolved terahertz spectroscopy of conjugated polymer/CdSe nanorod composites

    DEFF Research Database (Denmark)

    Cooke, David; Lek, Jun Y.; Krebs, Frederik C

    2010-01-01

    report ultrafast carrier dynamics in hybrid CdSe nanorod / poly(3-hexythiophene) (P3HT) bulk heterojunction films measured by time-resolved terahertz spectroscopy, and compare to the well studied P3HT/phenyl-C61-butyric acid methyl ester (PCBM) blend. Both films show an improved peak...... photoconductivity compared to P3HT alone, consistent with efficient charge transfer. The photoconductivity dynamics show fast, picosecond trapping or recombination in the hybrid blend while the all-organic film shows no such loss of mobile charge over ns time scales. The ac conductivity for all samples is well...

  8. Metal-insulator phase transition in a VO2 thin film observed with terahertz spectroscopy

    DEFF Research Database (Denmark)

    Jepsen, Peter Uhd; Fischer, Bernd M.; Thoman, Andreas

    2006-01-01

    We investigate the dielectric properties of a thin VO2 film in the terahertz frequency range in the vicinity of the semiconductor-metal phase transition. Phase-sensitive broadband spectroscopy in the frequency region below the phonon bands of VO2 gives insight into the conductive properties...... of the film during the phase transition. We compare our experimental data with models proposed for the evolution of the phase transition. The experimental data show that the phase transition occurs via the gradual growth of metallic domains in the film, and that the dielectric properties of the film...

  9. In vivo spectroscopy of healthy skin and pathology in terahertz frequency range

    International Nuclear Information System (INIS)

    Zaytsev, Kirill I; Gavdush, Arseniy A; Chernomyrdin, Nikita V; Karasik, Valeriy E; Yurchenko, Stanislav O; Kudrin, Konstantin G; Reshetov, Igor V

    2015-01-01

    Biomedical applications of terahertz (THz) technology and, in particular, THz pulsed spectroscopy have attracted considerable interest in the scientific community. A lot of papers have been dedicated to studying the ability for human disease diagnosis, including the diagnosis of human skin cancers. In this paper we have studied the THz material parameters and THz dielectric properties of human skin and pathology in vivo, and THz pulsed spectroscopy has been utilized for this purpose. We have found a contrast between material parameters of basal cell carcinoma and healthy skin, and we have also compared the THz material parameters of dysplastic and non-dysplastic pigmentary nevi in order to study the ability for early melanoma diagnosis. Significant differences between the THz material parameters of healthy skin and pathology have been detected, thus, THz pulsed spectroscopy promises to be become an effective tool for non-invasive diagnosis of skin neoplasms

  10. Quantitative determination of Auramine O by terahertz spectroscopy with 2DCOS-PLSR model

    Science.gov (United States)

    Zhang, Huo; Li, Zhi; Chen, Tao; Qin, Binyi

    2017-09-01

    Residues of harmful dyes such as Auramine O (AO) in herb and food products threaten the health of people. So, fast and sensitive detection techniques of the residues are needed. As a powerful tool for substance detection, terahertz (THz) spectroscopy was used for the quantitative determination of AO by combining with an improved partial least-squares regression (PLSR) model in this paper. Absorbance of herbal samples with different concentrations was obtained by THz-TDS in the band between 0.2THz and 1.6THz. We applied two-dimensional correlation spectroscopy (2DCOS) to improve the PLSR model. This method highlighted the spectral differences of different concentrations, provided a clear criterion of the input interval selection, and improved the accuracy of detection result. The experimental result indicated that the combination of the THz spectroscopy and 2DCOS-PLSR is an excellent quantitative analysis method.

  11. Insulin amyloid fibrillation studied by terahertz spectroscopy and other biophysical methods

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Rui [State Key Laboratory of Chemical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China); He, Mingxia [College of Precision Instrument and Optoelectronics Engineering, Tianjin University, Tianjin 300072 (China); Su, Rongxin, E-mail: surx@tju.edu.cn [State Key Laboratory of Chemical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China); Tianjin Key Laboratory of Membrane Science and Desalination Technology, Tianjin University, Tianjin 300072 (China); Yu, Yanjun [State Key Laboratory of Chemical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China); Qi, Wei; He, Zhimin [State Key Laboratory of Chemical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China); Tianjin Key Laboratory of Membrane Science and Desalination Technology, Tianjin University, Tianjin 300072 (China)

    2010-01-01

    Assembly and fibrillation of amyloid proteins are believed to play a key role in the etiology of various human diseases, including Alzheimer's, Parkinson's, Huntington's and type II diabetes. Insights into conformational changes and formation processes during amyloid fibrillation are essential for the clinical diagnosis and drug discovery. To study the changes in secondary, tertiary, quaternary structures, and the alteration in the collective vibrational mode density of states during the amyloid fibrillation, bovine insulin in 20% acetic acid was incubated at 60 {sup o}C, and its multi-level structures were followed by various biophysical techniques, including circular dichroism (CD), thioflavin T fluorescence (ThT), dynamic light scattering (DLS), electron microscopy, and terahertz (THz) absorption spectroscopy. The experimental data demonstrated a transformation of {alpha}-helix into {beta}-sheet starting at 26 h. This was followed by the aggregation of insulin, as shown by ThT binding, with a transition midpoint at 41 h, and by the bulk formation of mature aggregates after about 71 h. THz is a quick and non-invasive technique, which has the advantage of allowing the study of the conformational state of biomolecules and tissues. We first applied THz spectroscopy to study the amyloid fibrillation. At the terahertz frequency range of 0.2-2.0 THz, there was an apparent increase in both the absorbance and refractive index in THz spectra. Thus, THz is expected to provide a new way of looking into amyloid fibrillation.

  12. Reflectance spectroscopy and asteroid surface mineralogy

    International Nuclear Information System (INIS)

    Gaffey, M.J.; Bell, J.F.; Cruikshank, D.P.

    1989-01-01

    Information available from reflectance spectroscopy on the surface mineralogy of asteroids is discussed. Current spectral interpretive procedures used in the investigations of asteroid mineralogy are described. Present understanding of the nature and history of asteroids is discussed together with some still unresolved issues such as the source of ordinary chondrites. 100 refs

  13. Dynamic terahertz spectroscopy of gas molecules mixed with unwanted aerosol under atmospheric pressure using fibre-based asynchronous-optical-sampling terahertz time-domain spectroscopy

    Science.gov (United States)

    Hsieh, Yi-Da; Nakamura, Shota; Abdelsalam, Dahi Ghareab; Minamikawa, Takeo; Mizutani, Yasuhiro; Yamamoto, Hirotsugu; Iwata, Tetsuo; Hindle, Francis; Yasui, Takeshi

    2016-06-01

    Terahertz (THz) spectroscopy is a promising method for analysing polar gas molecules mixed with unwanted aerosols due to its ability to obtain spectral fingerprints of rotational transition and immunity to aerosol scattering. In this article, dynamic THz spectroscopy of acetonitrile (CH3CN) gas was performed in the presence of smoke under the atmospheric pressure using a fibre-based, asynchronous-optical-sampling THz time-domain spectrometer. To match THz spectral signatures of gas molecules at atmospheric pressure, the spectral resolution was optimized to 1 GHz with a measurement rate of 1 Hz. The spectral overlapping of closely packed absorption lines significantly boosted the detection limit to 200 ppm when considering all the spectral contributions of the numerous absorption lines from 0.2 THz to 1 THz. Temporal changes of the CH3CN gas concentration were monitored under the smoky condition at the atmospheric pressure during volatilization of CH3CN droplets and the following diffusion of the volatilized CH3CN gas without the influence of scattering or absorption by the smoke. This system will be a powerful tool for real-time monitoring of target gases in practical applications of gas analysis in the atmospheric pressure, such as combustion processes or fire accident.

  14. Sub-terahertz resonance spectroscopy of biological macromolecules and cells

    Science.gov (United States)

    Globus, Tatiana; Moyer, Aaron; Gelmont, Boris; Khromova, Tatyana; Sizov, Igor; Ferrance, Jerome

    2013-05-01

    Recently we introduced a Sub-THz spectroscopic system for characterizing vibrational resonance features from biological materials. This new, continuous-wave, frequency-domain spectroscopic sensor operates at room temperature between 315 and 480 GHz with spectral resolution of at least 1 GHz and utilizes the source and detector components from Virginia Diode, Inc. In this work we present experimental results and interpretation of spectroscopic signatures from bacterial cells and their biological macromolecule structural components. Transmission and absorption spectra of the bacterial protein thioredoxin, DNA and lyophilized cells of Escherichia coli (E. coli), as well as spores of Bacillus subtillis and B. atrophaeus have been characterized. Experimental results for biomolecules are compared with absorption spectra calculated using molecular dynamics simulation, and confirm the underlying physics for resonance spectroscopy based on interactions between THz radiation and vibrational modes or groups of modes of atomic motions. Such interactions result in multiple intense and narrow specific resonances in transmission/absorption spectra from nano-gram samples with spectral line widths as small as 3 GHz. The results of this study indicate diverse relaxation dynamic mechanisms relevant to sub-THz vibrational spectroscopy, including long-lasting processes. We demonstrate that high sensitivity in resolved specific absorption fingerprints provides conditions for reliable detection, identification and discrimination capability, to the level of strains of the same bacteria, and for monitoring interactions between biomaterials and reagents in near real-time. Additionally, it creates the basis for the development of new types of advanced biological sensors through integrating the developed system with a microfluidic platform for biomaterial samples.

  15. Detection of DNA oligonucleotides with base mutations by terahertz spectroscopy and microstructures.

    Directory of Open Access Journals (Sweden)

    Mingjie Tang

    Full Text Available DNA oligonucleotides with a 5-base mutation at the 3'-terminus were investigated by terahertz (THz spectroscopy in a marker-free manner. The four single-stranded oligonucleotides with 17nt have been detected with specificity on a microfluidic chip, and corroborated by spectral measurements with split-ring resonators. The number of hydrogen bonds formed between the oligonucleotide and its surrounding water molecules, deemed a key contribution to the THz absorption of biological solutions, was explored by molecular dynamics simulations to explain the experimental findings. Our work underlies the feasibility of THz spectroscopy combined with microstructures for marker-free detection of DNA, which may form the basis of a prospective diagnostic tool for studying genic mutation.

  16. Application of terahertz spectroscopy for characterization of biologically active organic molecules in natural environment

    Science.gov (United States)

    Karaliūnas, Mindaugas; Jakštas, Vytautas; Nasser, Kinan E.; Venckevičius, Rimvydas; Urbanowicz, Andrzej; Kašalynas, Irmantas; Valušis, Gintaras

    2016-09-01

    In this work, a comparative research of biologically active organic molecules in its natural environment using the terahertz (THz) time domain spectroscopy (TDS) and Fourier transform spectroscopy (FTS) systems is carried out. Absorption coefficient and refractive index of Nicotiana tabacum L. leaves containing nicotine, Cannabis sativa L. leaves containing tetrahydrocannabinol, and Humulu lupulus L. leaves containing α-acids, active organic molecules that obtain in natural environment, were measured in broad frequency range from 0.1 to 13 THz at room temperature. In the spectra of absorption coefficient the features were found to be unique for N. tabacum, C. sativa and H. lupulus. Moreover, those features can be exploited for identification of C. sativa sex and N. tabacum origin. The refractive index can be also used to characterize different species.

  17. Terahertz spectroscopy for the study of paraffin-embedded gastric cancer samples

    Science.gov (United States)

    Wahaia, Faustino; Kasalynas, Irmantas; Seliuta, Dalius; Molis, Gediminas; Urbanowicz, Andrzej; Carvalho Silva, Catia D.; Carneiro, Fatima; Valusis, Gintaras; Granja, Pedro L.

    2015-01-01

    Terahertz (THz) spectroscopy constitute promising technique for biomedical applications as a complementary and powerful tool for diseases screening specially for early cancer diagnostic. The THz radiation is not harmful to biological tissues. As increased blood supply in cancer-affected tissues and consequent local increase in tissue water content makes THz technology a potentially attractive. In the present work, samples of healthy and adenocarcinoma-affected gastric tissue were analyzed using transmission time-domain THz spectroscopy (THz-TDS). The work shows the capability of the technique to distinguish between normal and cancerous regions in dried and paraffin-embedded samples. Plots of absorption coefficient α and refractive index n of normal and cancer affected tissues, are presented and the conditions for discrimination between normal and affected tissues are discussed.

  18. Josephson spectroscopy of terahertz losses in [100]-tilt YBa2Cu3O7-x bicrystal junctions

    International Nuclear Information System (INIS)

    Divin, Y; Lyatti, M

    2008-01-01

    Terahertz losses in the [100]-tilt YBa 2 Cu 3 O 7-x grain-boundary junctions were studied using admittance Josephson spectroscopy. The I-Vcurves of the [100]-tilt YBa 2 Cu 3 O 7-x junctions, when annealed in atomic oxygen, were described by the resistively shunted junction model (RSJ) with an accuracy of better than 0.5% at the temperature range, where the characteristic voltage I c R n n -1 . At low temperatures, where I c R n >> kT/2e, the absorption of Josephson radiation by optical phonon modes in YBa 2 Cu 3 O 7-x was found to be reflected in the I-V curve of the [100]-tilt junctions. The most prominent structure is situated at the voltages V ∼ 9.5 mV, which gives the corresponding Josephson frequency of 4.6 THz in good agreement with the frequency of the strongest IR active optical phonon mode in YBa 2 Cu 3 O 7-x . Assignment of additional lines in the derived losses is discussed according to available data on lattice dynamic calculations and experimental data for a dynamic conduction Reσ 1 (f) of YBa 2 Cu 3 O 7-x . Josephson spectroscopy might be useful for study of low-energy excitations in high-T c materials

  19. Terahertz spectroscopy of shift currents resulting from asymmetric (110)-oriented GaAs/AlGaAs quantum wells

    International Nuclear Information System (INIS)

    Priyadarshi, Shekhar; Leidinger, Markus; Pierz, Klaus; Racu, Ana M.; Siegner, Uwe; Bieler, Mark; Dawson, Philip

    2009-01-01

    We report the observation and the study of an additional shift current tensor element in (110)-oriented GaAs quantum wells, which arises from an out-of-plane asymmetry of the quantum well structure. The current resulting from this tensor element is optically induced with 150 fs laser pulses and detected by measuring the simultaneously emitted terahertz radiation. This terahertz spectroscopy of shift currents is a powerful technique for symmetry investigations, which shows, for example, that our nominally symmetric (110)-oriented GaAs/AlGaAs quantum wells grown by molecular beam epitaxy are in reality asymmetric structures with different right and left interfaces.

  20. Characterisation of historic plastics using terahertz time-domain spectroscopy and pulsed imaging.

    Science.gov (United States)

    Pastorelli, Gianluca; Trafela, Tanja; Taday, Phillip F; Portieri, Alessia; Lowe, David; Fukunaga, Kaori; Strlič, Matija

    2012-05-01

    Terahertz (THz) time-domain spectroscopy and 3D THz pulsed imaging have been explored with regard to polymer materials, both commodity and historic polymers. A systematic spectroscopic study of a wide range of different polymer materials showed significant differences in their spectra. Polyolefins and polystyrenes generally exhibit lower absorption than other examined polymers, various cellulose derivates, poly(vinyl chloride), poly(methyl methacrylate), polyamide, hard rubber and phenol formaldehyde resin, the last of these exhibiting the most intense absorption over the entire range, 0.15-4.2 THz. It was also examined how the presence of plasticisers in poly(vinyl chloride), the presence of fillers in polypropylene, and the degree of branching in polyethylene and polystyrene affect the spectra; inorganic fillers in polypropylene affected the absorption most. With 3D THz pulsed imaging, features in polymer objects were explored, appearing either as integral parts of the material (coatings and pores in foams) or as a consequence of physical deterioration (cracks, delamination). All of these features of various complexities can be successfully imaged in 3D. Terahertz technology is thus shown to have significant potential for both chemical and structural characterisation of polymers, which will be of interest to heritage science, but also to the polymer industry and development of analytical technologies in general.

  1. Application of terahertz spectroscopy and theoretical calculation in dimethylurea isomers investigation

    Science.gov (United States)

    Zhao, Yonghong; Li, Zhi; Liu, Jianjun; Chen, Tao; Zhang, Huo; Qin, Binyi; Wu, Yifang

    2018-03-01

    The characteristic absorption spectra of two structural isomers of dimethylurea(DMU) in 0.6-1.8 THz region have been measured using terahertz time-domain spectroscopy (THZ-TDS) at room temperature. Significant differences have been found between their terahertz spectra and implied that the THZ-TDS is an effective means of identifying structural isomers. To simulate their spectra, calculations on single molecule and cluster of 1,1-DMU and 1,3-DMU were performed, and we found that the cluster calculations using DFT-D3 method are better to predict the experimental spectra. Using the normal mode as displacements in redundant internal coordinates and the GaussView program, most observed THz vibrational modes are assigned to bending and rocking modes related to the intermolecular hydrogen bonding interactions, and twisting mode of ethyl groups. The different spectral features of two isomers mainly arise from different intermolecular hydrogen bonds resulting from different atom arrangements in molecules and different molecule arrangements in crystals. Using the reduced-density-gradient (RDG) analysis, the positions and types of intermolecular hydrogen bonding interactions in 1,1-DMU and 1,3-DMU crystals are visualized. Therefore, we can confirm that THz-TDS can be used as an effective means for the recognition of structural isomers and detection of intermolecular hydrogen bonding interactions in these crystals.

  2. Gas spectroscopy with integrated frequency monitoring through self-mixing in a terahertz quantum-cascade laser.

    Science.gov (United States)

    Chhantyal-Pun, Rabi; Valavanis, Alexander; Keeley, James T; Rubino, Pierluigi; Kundu, Iman; Han, Yingjun; Dean, Paul; Li, Lianhe; Davies, A Giles; Linfield, Edmund H

    2018-05-15

    We demonstrate a gas spectroscopy technique, using self-mixing in a 3.4 terahertz quantum-cascade laser (QCL). All previous QCL spectroscopy techniques have required additional terahertz instrumentation (detectors, mixers, or spectrometers) for system pre-calibration or spectral analysis. By contrast, our system self-calibrates the laser frequency (i.e., with no external instrumentation) to a precision of 630 MHz (0.02%) by analyzing QCL voltage perturbations in response to optical feedback within a 0-800 mm round-trip delay line. We demonstrate methanol spectroscopy by introducing a gas cell into the feedback path and show that a limiting absorption coefficient of ∼1×10 -4   cm -1 is resolvable.

  3. Far-infrared vibrational modes of DNA components studied by terahertz time-domain spectroscopy

    International Nuclear Information System (INIS)

    Fischer, B M; Walther, M; Jepsen, P Uhd

    2002-01-01

    The far-infrared dielectric function of a wide range of organic molecules is dominated by vibrations involving a substantial fraction of the atoms forming the molecule and motion associated with intermolecular hydrogen bond vibrations. Due to their collective nature such modes are highly sensitive to the intra- and intermolecular structure and thus provide a unique fingerprint of the conformational state of the molecule and effects of its environment. We demonstrate the use of terahertz time-domain spectroscopy (THz-TDS) for recording the far-infrared (0.5-4.0 THz) dielectric function of the four nucleobases and corresponding nucleosides forming the building blocks of deoxyribose nucleic acid (DNA). We observe numerous distinct spectral features with large differences between the molecules in both frequency-dependent absorption coefficient and index of refraction. Assisted by results from density-functional calculations we interpret the origin of the observed resonances as vibrations of hydrogen bonds between the molecules

  4. Rotational spectroscopy and dynamics of carbonyl sulphide studied by terahertz free induction decays signals

    Science.gov (United States)

    Bigourd, D.; Mouret, G.; Cuisset, A.; Hindle, F.; Fertein, E.; Bocquet, R.

    2008-06-01

    A terahertz time domain spectroscopy experiment is used to study the coherent re-emission after exciting more than 60 energy rotational states of OCS molecules in gas phase. Due to the regular structure of the absorption spectrum of such linear molecules, a set of subsequent pulses separated by 82.6 ps is re-radiated from the vapour and recorded up to 450 ps. A model based on a linear response of the gas and by use of "Maxwell-Bloch" equations has permitted the re-emitted free induced decay to be investigated. Spectroscopic parameters, such as rotational constant, centrifugal distortion coefficient and relaxation times are responsible for the temporal shape and so can be evaluated. The influence of the optical thickness to access the relaxation times is discussed.

  5. Rapid determination of saponification value and polymer content of vegetable and fish oils by terahertz spectroscopy.

    Science.gov (United States)

    Jiang, Feng Ling; Ikeda, Ikuo; Ogawa, Yuichi; Endo, Yasushi

    2012-01-01

    A rapid method for determining the saponification value (SV) and polymer content of vegetable and fish oils using the terahertz (THz) spectroscopy was developed. When the THz absorption spectra for vegetable and fish oils were measured in the range of 20 to 400 cm⁻¹, two peaks were seen at 77 and 328 cm⁻¹. The level of absorbance at 77 cm⁻¹ correlated well with the SV. When the THz absorption spectra of thermally treated high-oleic safflower oils were measured, the absorbance increased with heating time. The polymer content in thermally treated oil correlated with the absorbance at 77 cm⁻¹. These results demonstrate that the THz spectrometry is a suitable non-destructive technique for the rapid determination of the SV and polymer content of vegetable and fish oils.

  6. Terahertz magneto-optical spectroscopy of a two-dimensional hole gas

    Energy Technology Data Exchange (ETDEWEB)

    Kamaraju, N., E-mail: nkamaraju@lanl.gov; Taylor, A. J.; Prasankumar, R. P., E-mail: rpprasan@lanl.gov [Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Pan, W.; Reno, J. [Sandia National Laboratories, Albuquerque, New Mexico 87123 (United States); Ekenberg, U. [Semiconsultants, Brunnsgrnd 12, SE-18773 Täby (Sweden); Gvozdić, D. M. [School of Electrical Engineering, University of Belgrade, Belgrade 11120 (Serbia); Boubanga-Tombet, S. [Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Research Institute of Electrical Communication, Tohoku University, 2-1-1 Katahira, Aoba-Ku, Sendai (Japan); Upadhya, P. C. [Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Laboratory for Electro-Optics Systems, Indian Space Research Organization, Bangalore 560058 (India)

    2015-01-19

    Two-dimensional hole gases (2DHGs) have attracted recent attention for their unique quantum physics and potential applications in areas including spintronics and quantum computing. However, their properties remain relatively unexplored, motivating the use of different techniques to study them. We used terahertz magneto-optical spectroscopy to investigate the cyclotron resonance frequency in a high mobility 2DHG, revealing a nonlinear dependence on the applied magnetic field. This is shown to be due to the complex non-parabolic valence band structure of the 2DHG, as verified by multiband Landau level calculations. We also find that impurity scattering dominates cyclotron resonance decay in the 2DHG, in contrast with the dominance of superradiant damping in two-dimensional electron gases. Our results shed light on the properties of 2DHGs, motivating further studies of these unique 2D nanosystems.

  7. Characterization of Inclusions in Evolution of Sodium Sulfate Using Terahertz Time-domain Spectroscopy.

    Science.gov (United States)

    Bao, Rima; Wu, Zhikui; Li, Hao; Wang, Fang; Miao, Xinyang; Feng, Chengjing

    2017-01-01

    The study of fluid inclusion is one of the important means to understanding the evolution of mineral crystals, and can therefore provide original information of mineral evolution. In the process of evolution, outside factors such as temperature and pressure, directly affect the number and size of inclusions, and thus are related to the properties of crystals. In this paper, terahertz time-domain spectroscopy (THz-TDS) was used to detect sodium sulfate crystals with different growth temperatures, and absorption coefficient spectra of the samples were obtained. It is suggested that the evolution of sodium sulfate could be divided into two stages, and 80°C was the turning point. X-ray diffraction (XRD) and polarizing microscopy were used to support this conclusion. The research showed that THz-TDS could characterize the evolution of mineral crystals, and it had a unique advantage in terms of crystal evolution.

  8. Coherent Two-Dimensional Terahertz Magnetic Resonance Spectroscopy of Collective Spin Waves.

    Science.gov (United States)

    Lu, Jian; Li, Xian; Hwang, Harold Y; Ofori-Okai, Benjamin K; Kurihara, Takayuki; Suemoto, Tohru; Nelson, Keith A

    2017-05-19

    We report a demonstration of two-dimensional (2D) terahertz (THz) magnetic resonance spectroscopy using the magnetic fields of two time-delayed THz pulses. We apply the methodology to directly reveal the nonlinear responses of collective spin waves (magnons) in a canted antiferromagnetic crystal. The 2D THz spectra show all of the third-order nonlinear magnon signals including magnon spin echoes, and 2-quantum signals that reveal pairwise correlations between magnons at the Brillouin zone center. We also observe second-order nonlinear magnon signals showing resonance-enhanced second-harmonic and difference-frequency generation. Numerical simulations of the spin dynamics reproduce all of the spectral features in excellent agreement with the experimental 2D THz spectra.

  9. Degradation diagnosis of transformer insulating oils with terahertz time-domain spectroscopy

    Science.gov (United States)

    Kang, Seung Beom; Kim, Won-Seok; Chung, Dong Chul; Joung, Jong Man; Kwak, Min Hwan

    2017-12-01

    We report the frequency-dependent complex optical constants, refractive index and absorption, and complex dielectric properties over the frequency range from 0.2 to 3.0 THz for aged power transformer mineral insulating oils. These results have been obtained using terahertz time-domain spectroscopy (THz-TDS) and demonstrate the double-Debye relaxation behavior of the mineral insulating oil. The measured complex optical and dielectric characteristics can be important benchmarks for liquid molecular dynamics and theoretical studies of insulating oils. Due to clear differences in THz responses of aged mineral insulating oils, THz-TDS can be used as a novel on-site diagnostic technique to monitor the insulation condition in aged power transformers and may be valuable alternative to characterize other developing eco-friendly insulating oils and industrial liquids.

  10. Identification of Transgenic Organisms Based on Terahertz Spectroscopy and Hyper Sausage Neuron

    Science.gov (United States)

    Liu, J.; Li, Zh.; Hu, F.; Chen, T.; Du, Y.; Xin, H.

    2015-03-01

    This paper presents a novel approach for identifi cation of terahertz (THz) spectra of genetically modifi ed organisms (GMOs) based on hyper sausage neuron (HSN), and THz transmittance spectra of some typical transgenic sugarbeet samples are investigated to demonstrate its feasibility. Principal component analysis (PCA) is applied to extract features of the spectrum data, and instead of the original spectrum data, the feature signals are fed into the HSN pattern recognition, a new multiple weights neural network (MWNN). The experimental result shows that the HSN model not only can correctly classify different types of transgenic sugar-beets, but also can reject nonsimilar samples of the same type. The proposed approach provides a new effective method for detection and identification of genetically modified organisms by using THz spectroscopy.

  11. Hyper sausage neuron: Recognition of transgenic sugar-beet based on terahertz spectroscopy

    Science.gov (United States)

    Liu, Jianjun; Li, Zhi; Hu, Fangrong; Chen, Tao; Du, Yong; Xin, Haitao

    2015-01-01

    This paper presents a novel approach for identification of terahertz (THz) spectral of genetically modified organisms (GMOs) based on Hyper Sausage Neuron (HSN), and THz transmittance spectra of some typical transgenic sugar-beet samples are investigated to demonstrate its feasibility. Principal component analysis (PCA) is applied to extract features of the spectrum data, and instead of the original spectrum data, the feature signals are fed into the HSN pattern recognition, a new multiple weights neural network (MWNN). The experimental result shows that the HSN model not only can correctly classify different types of transgenic sugar-beets, but also can reject identity non similar samples in the same type. The proposed approach provides a new effective method for detection and identification of GMOs by using THz spectroscopy.

  12. Collective vibrational spectra of α- and γ-glycine studied by terahertz and Raman spectroscopy

    International Nuclear Information System (INIS)

    Shi Yulei; Wang Li

    2005-01-01

    Terahertz time-domain spectroscopy is used to investigate the absorption and dispersion of polycrystalline α- and γ-glycine in the spectral region 0.5-3.0 THz. The spectra exhibit distinct features in these two crystalline phases. The observed far-infrared responses are attributed to intermolecular vibrational modes mediated by hydrogen bonds. We also measure the Raman spectra of the polycrystalline and dissolved glycine in the frequency range 28-3900 cm -1 . The results show that all the vibrational modes below 200 cm -1 are nonlocalized but are of a collective (phonon-like) nature. Furthermore, the temperature dependence of the Raman spectra of α-glycine agrees with the anharmonicity mechanism of the vibrational potentials

  13. Transmission versus reflectance spectroscopy for quantitation

    Science.gov (United States)

    Gardner, Craig M.

    2018-01-01

    The objective of this work was to compare the accuracy of analyte concentration estimation when using transmission versus diffuse reflectance spectroscopy of a scattering medium. Monte Carlo ray tracing of light through the medium was used in conjunction with pure component absorption spectra and Beer-Lambert absorption along each ray's pathlength to generate matched sets of pseudoabsorbance spectra, containing water and six analytes present in skin. PLS regression models revealed an improvement in accuracy when using transmission compared to reflectance for a range of medium thicknesses and instrument noise levels. An analytical expression revealed the source of the accuracy degradation with reflectance was due both to the reduced collection efficiency for a fixed instrument etendue and to the broad pathlength distribution that detected light travels in the medium before exiting from the incident side.

  14. Quantitative detection of melamine based on terahertz time-domain spectroscopy

    Science.gov (United States)

    Zhao, Xiaojing; Wang, Cuicui; Liu, Shangjian; Zuo, Jian; Zhou, Zihan; Zhang, Cunlin

    2018-01-01

    Melamine is an organic base and a trimer of cyanamide, with a 1, 3, 5-triazine skeleton. It is usually used for the production of plastics, glue and flame retardants. Melamine combines with acid and related compounds to form melamine cyanurate and related crystal structures, which have been implicated as contaminants or biomarkers in protein adulterations by lawbreakers, especially in milk powder. This paper is focused on developing an available method for quantitative detection of melamine in the fields of security inspection and nondestructive testing based on THz-TDS. Terahertz (THz) technology has promising applications for the detection and identification of materials because it exhibits the properties of spectroscopy, good penetration and safety. Terahertz time-domain spectroscopy (THz-TDS) is a key technique that is applied to spectroscopic measurement of materials based on ultrafast femtosecond laser. In this study, the melamine and its mixture with polyethylene powder in different consistence are measured using the transmission THz-TDS. And we obtained the refractive index spectra and the absorption spectrum of different concentrations of melamine on 0.2-2.8THz. In the refractive index spectra, it is obvious to see that decline trend with the decrease of concentration; and in the absorption spectrum, two peaks of melamine at 1.98THz and 2.28THz can be obtained. Based on the experimental result, the absorption coefficient and the consistence of the melamine in the mixture are determined. Finally, methods for quantitative detection of materials in the fields of nondestructive testing and quality control based on THz-TDS have been studied.

  15. Quality control and authentication of packaged integrated circuits using enhanced-spatial-resolution terahertz time-domain spectroscopy and imaging

    Science.gov (United States)

    Ahi, Kiarash; Shahbazmohamadi, Sina; Asadizanjani, Navid

    2018-05-01

    In this paper, a comprehensive set of techniques for quality control and authentication of packaged integrated circuits (IC) using terahertz (THz) time-domain spectroscopy (TDS) is developed. By material characterization, the presence of unexpected materials in counterfeit components is revealed. Blacktopping layers are detected using THz time-of-flight tomography, and thickness of hidden layers is measured. Sanded and contaminated components are detected by THz reflection-mode imaging. Differences between inside structures of counterfeit and authentic components are revealed through developing THz transmission imaging. For enabling accurate measurement of features by THz transmission imaging, a novel resolution enhancement technique (RET) has been developed. This RET is based on deconvolution of the THz image and the THz point spread function (PSF). The THz PSF is mathematically modeled through incorporating the spectrum of the THz imaging system, the axis of propagation of the beam, and the intensity extinction coefficient of the object into a Gaussian beam distribution. As a result of implementing this RET, the accuracy of the measurements on THz images has been improved from 2.4 mm to 0.1 mm and bond wires as small as 550 μm inside the packaging of the ICs are imaged.

  16. Investigating tautomeric polymorphism in crystalline anthranilic acid using terahertz spectroscopy and solid-state density functional theory.

    Science.gov (United States)

    Delaney, Sean P; Witko, Ewelina M; Smith, Tiffany M; Korter, Timothy M

    2012-08-02

    Terahertz spectroscopy is sensitive to the interactions between molecules in the solid-state and recently has emerged as a new analytical tool for investigating polymorphism. Here, this technique is applied for the first time to the phenomenon of tautomeric polymorphism where the crystal structures of anthranilic acid (2-aminobenzoic acid) have been investigated. Three polymorphs of anthranilic acid (denoted Forms I, II and III) were studied using terahertz spectroscopy and the vibrational modes and relative polymorph stabilities analyzed using solid-state density functional theory calculations augmented with London dispersion force corrections. Form I consists of both neutral and zwitterionic molecules and was found to be the most stable polymorph as compared to Forms II and III (both containing only neutral molecules). The simulations suggest that a balance between steric interactions and electrostatic forces is responsible for the favoring of the mixed neutral/zwitterion solid over the all neutral or all zwitterion crystalline arrangements.

  17. Electrically continuous graphene from single crystal copper verified by terahertz conductance spectroscopy and micro four-point probe

    DEFF Research Database (Denmark)

    Buron, Jonas Christian Due; Pizzocchero, Filippo; Jessen, Bjarke Sørensen

    2014-01-01

    noninvasive conductance characterization methods: ultrabroadband terahertz time-domain spectroscopy and micro four-point probe, which probe the electrical properties of the graphene film on different length scales, 100 nm and 10 μm, respectively. Ultrabroadband terahertz time-domain spectroscopy allows......- and microscale electrical continuity of single layer graphene grown on centimeter-sized single crystal copper with that of previously studied graphene films, grown on commercially available copper foil, after transfer to SiO2 surfaces. The electrical continuity of the graphene films is analyzed using two....... Micro four-point probe resistance values measured on graphene grown on single crystalline copper in two different voltage-current configurations show close agreement with the expected distributions for a continuous 2D conductor, in contrast with previous observations on graphene grown on commercial...

  18. Thin film polycrystalline Si solar cells studied in transient regime by optical pump-terahertz probe spectroscopy

    Czech Academy of Sciences Publication Activity Database

    Pikna, Peter; Skoromets, Volodymyr; Becker, C.; Fejfar, Antonín; Kužel, Petr

    2015-01-01

    Roč. 107, č. 23 (2015), "233901-1"-"233901-5" ISSN 0003-6951 R&D Projects: GA ČR GA13-12386S Grant - others:AVČR(CZ) M100101216 Institutional support: RVO:68378271 Keywords : thin film polycrystalline silicon * terahertz spectroscopy * passivation * Suns-Voc method * defects Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.142, year: 2015

  19. Photoconductive, dielectric and percolation properties of anodic TiO.sub.2./sub. nanotubes studied by terahertz spectroscopy

    Czech Academy of Sciences Publication Activity Database

    Kuchařík, Jiří; Sopha, H.; Krbal, M.; Rychetský, Ivan; Kužel, Petr; Macák, J. M.; Němec, Hynek

    2018-01-01

    Roč. 51, č. 1 (2018), s. 1-9, č. článku 014004. ISSN 0022-3727 R&D Projects: GA ČR GA17-03662S Institutional support: RVO:68378271 Keywords : anodic TiO 2 nanotubes * terahertz spectroscopy * charge transport * dielectric properties Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics , supercond.) Impact factor: 2.588, year: 2016

  20. Estimating soil zinc concentrations using reflectance spectroscopy

    Science.gov (United States)

    Sun, Weichao; Zhang, Xia

    2017-06-01

    Soil contamination by heavy metals has been an increasingly severe threat to nature environment and human health. Efficiently investigation of contamination status is essential to soil protection and remediation. Visible and near-infrared reflectance spectroscopy (VNIRS) has been regarded as an alternative for monitoring soil contamination by heavy metals. Generally, the entire VNIR spectral bands are employed to estimate heavy metal concentration, which lacks interpretability and requires much calculation. In this study, 74 soil samples were collected from Hunan Province, China and their reflectance spectra were used to estimate zinc (Zn) concentration in soil. Organic matter and clay minerals have strong adsorption for Zn in soil. Spectral bands associated with organic matter and clay minerals were used for estimation with genetic algorithm based partial least square regression (GA-PLSR). The entire VNIR spectral bands, the bands associated with organic matter and the bands associated with clay minerals were incorporated as comparisons. Root mean square error of prediction, residual prediction deviation, and coefficient of determination (R2) for the model developed using combined bands of organic matter and clay minerals were 329.65 mg kg-1, 1.96 and 0.73, which is better than 341.88 mg kg-1, 1.89 and 0.71 for the entire VNIR spectral bands, 492.65 mg kg-1, 1.31 and 0.40 for the organic matter, and 430.26 mg kg-1, 1.50 and 0.54 for the clay minerals. Additionally, in consideration of atmospheric water vapor absorption in field spectra measurement, combined bands of organic matter and absorption around 2200 nm were used for estimation and achieved high prediction accuracy with R2 reached 0.640. The results indicate huge potential of soil reflectance spectroscopy in estimating Zn concentrations in soil.

  1. EDITORIAL: Terahertz nanotechnology Terahertz nanotechnology

    Science.gov (United States)

    Demming, Anna; Tonouchi, Masayoshi; Reno, John L.

    2013-05-01

    A useful synergy is being established between terahertz research and nanotechnology. High power sources [1-3] and detectors [4] in what was once considered the terahertz 'frequency gap' [5] in the electromagnetic spectrum have stimulated research with huge potential benefits in a range of industries including food, medicine and security, as well as fundamental physics and astrophysics. This special section, with guest editors Masayoshi Tonouchi and John Reno, gives a glimpse of the new horizons nanotechnology is broaching in terahertz research. While the wavelengths relevant to the terahertz domain range from hundreds of micrometres to millimetres, structures at the nanoscale reveal interesting low energy dynamics in this region. As a result terahertz spectroscopy techniques are becoming increasingly important in nanomaterial characterization, as demonstrated in this special section by colleagues at the University of Oxford in the UK and the Australian National University. They use terahertz spectroscopy to identify the best nanostructure parameters for specific applications [6]. The low energy dynamics in nanostructures also makes them valuable tools for terahertz detection [7]. In addition the much sought after terahertz detection over broadband frequency ranges has been demonstrated, providing versatility that has been greatly in demand, particularly in spectroscopy applications [8, 9]. Also in this special section, researchers in Germany and China tackle some of the coupling issues in terahertz time domain spectroscopy with an emitter specifically well suited for systems operated with an amplified fibre [3]. 'In medical imaging, the advantage of THz radiation is safety, because its energy is much lower than the ionization energy of biological molecules, in contrast to hazardous x-ray radiation,' explains Joo-Hiuk Son from the University of Seoul in Korea in his review [10]. As he also points out, the rotational and vibrational energies of water molecules are

  2. Design Considerations for Integration of Terahertz Time-Domain Spectroscopy in Microfluidic Platforms

    Directory of Open Access Journals (Sweden)

    Rasha Al-Hujazy

    2018-03-01

    Full Text Available Microfluidic platforms have received much attention in recent years. In particular, there is interest in combining spectroscopy with microfluidic platforms. This work investigates the integration of microfluidic platforms and terahertz time-domain spectroscopy (THz-TDS systems. A semiclassical computational model is used to simulate the emission of THz radiation from a GaAs photoconductive THz emitter. This model incorporates white noise with increasing noise amplitude (corresponding to decreasing dynamic range values. White noise is selected over other noise due to its contributions in THz-TDS systems. The results from this semiclassical computational model, in combination with defined sample thicknesses, can provide the maximum measurable absorption coefficient for a microfluidic-based THz-TDS system. The maximum measurable frequencies for such systems can be extracted through the relationship between the maximum measurable absorption coefficient and the absorption coefficient for representative biofluids. The sample thickness of the microfluidic platform and the dynamic range of the THz-TDS system play a role in defining the maximum measurable frequency for microfluidic-based THz-TDS systems. The results of this work serve as a design tool for the development of such systems.

  3. Adaptive sampling dual terahertz comb spectroscopy using dual free-running femtosecond lasers.

    Science.gov (United States)

    Yasui, Takeshi; Ichikawa, Ryuji; Hsieh, Yi-Da; Hayashi, Kenta; Cahyadi, Harsono; Hindle, Francis; Sakaguchi, Yoshiyuki; Iwata, Tetsuo; Mizutani, Yasuhiro; Yamamoto, Hirotsugu; Minoshima, Kaoru; Inaba, Hajime

    2015-06-02

    Terahertz (THz) dual comb spectroscopy (DCS) is a promising method for high-accuracy, high-resolution, broadband THz spectroscopy because the mode-resolved THz comb spectrum includes both broadband THz radiation and narrow-line CW-THz radiation characteristics. In addition, all frequency modes of a THz comb can be phase-locked to a microwave frequency standard, providing excellent traceability. However, the need for stabilization of dual femtosecond lasers has often hindered its wide use. To overcome this limitation, here we have demonstrated adaptive-sampling THz-DCS, allowing the use of free-running femtosecond lasers. To correct the fluctuation of the time and frequency scales caused by the laser timing jitter, an adaptive sampling clock is generated by dual THz-comb-referenced spectrum analysers and is used for a timing clock signal in a data acquisition board. The results not only indicated the successful implementation of THz-DCS with free-running lasers but also showed that this configuration outperforms standard THz-DCS with stabilized lasers due to the slight jitter remained in the stabilized lasers.

  4. Discrimination and Measurements of Three Flavonols with Similar Structure Using Terahertz Spectroscopy and Chemometrics

    Science.gov (United States)

    Yan, Ling; Liu, Changhong; Qu, Hao; Liu, Wei; Zhang, Yan; Yang, Jianbo; Zheng, Lei

    2018-03-01

    Terahertz (THz) technique, a recently developed spectral method, has been researched and used for the rapid discrimination and measurements of food compositions due to its low-energy and non-ionizing characteristics. In this study, THz spectroscopy combined with chemometrics has been utilized for qualitative and quantitative analysis of myricetin, quercetin, and kaempferol with concentrations of 0.025, 0.05, and 0.1 mg/mL. The qualitative discrimination was achieved by KNN, ELM, and RF models with the spectra pre-treatments. An excellent discrimination (100% CCR in the prediction set) could be achieved using the RF model. Furthermore, the quantitative analyses were performed by partial least square regression (PLSR) and least squares support vector machine (LS-SVM). Comparing to the PLSR models, the LS-SVM yielded better results with low RMSEP (0.0044, 0.0039, and 0.0048), higher Rp (0.9601, 0.9688, and 0.9359), and higher RPD (8.6272, 9.6333, and 7.9083) for myricetin, quercetin, and kaempferol, respectively. Our results demonstrate that THz spectroscopy technique is a powerful tool for identification of three flavonols with similar chemical structures and quantitative determination of their concentrations.

  5. Optical Reflection Spectroscopy of GEO Objects

    Science.gov (United States)

    Seitzer, Patrick; Cardona, Tammaso; Lederer, Susan M.; Cowardin, Heather; Abercromby, Kira J.; Barker, Edwin S.; Bedard, Donald

    2013-01-01

    We report on optical reflection spectroscopy of geosynchronous (GEO) objects in the US Space Surveillance Network (SSN) catalog. These observations were obtained using imaging spectrographs on the 6.5-m Magellan telescopes at the Las Campanas Observatory in Chile. Our goal is to determine the composition of these objects by comparing these spectral observations with ground-based laboratory measurements of spacecraft materials. The observations are all low resolution (1 nm after smoothing) obtained through a 5 arcsecond wide slit and using a grism as the dispersing element. The spectral range covered was from 450 nm to 800 nm. All spectra were flux calibrated using observations of standard stars with the exact same instrumental setup. An effort was made to obtain all observations within a limited range of topocentric phase angle, although the solar incident angle is unknown due to the lack of any knowledge of the attitude of the observed surface at the time of observation.

  6. Reflectance spectroscopy of organic compounds: 1. Alkanes

    Science.gov (United States)

    Clark, R.N.; Curchin, J.M.; Hoefen, T.M.; Swayze, G.A.

    2009-01-01

    Reflectance spectra of the organic compounds comprising the alkane series are presented from the ultraviolet to midinfrared, 0.35 to 15.5 /??m. Alkanes are hydrocarbon molecules containing only single carbon-carbon bonds, and are found naturally on the Earth and in the atmospheres of the giant planets and Saturn's moon, Titan. This paper presents the spectral properties of the alkanes as the first in a series of papers to build a spectral database of organic compounds for use in remote sensing studies. Applications range from mapping the environment on the Earth, to the search for organic molecules and life in the solar system and throughout the. universe. We show that the spectral reflectance properties of organic compounds are rich, with major diagnostic spectral features throughout the spectral range studied. Little to no spectral change was observed as a function of temperature and only small shifts and changes in the width of absorption bands were observed between liquids and solids, making remote detection of spectral properties throughout the solar system simpler. Some high molecular weight organic compounds contain single-bonded carbon chains and have spectra similar to alkanes even ' when they fall into other families. Small spectral differences are often present allowing discrimination among some compounds, further illustrating the need to catalog spectral properties for accurate remote sensing identification with spectroscopy.

  7. TERAHERTZ SPECTROSCOPY AND GLOBAL ANALYSIS OF THE BENDING VIBRATIONS OF ACETYLENE 12C2D2

    International Nuclear Information System (INIS)

    Yu Shanshan; Drouin, Brian J.; Pearson, John C.; Pickett, Herbert M.; Lattanzi, Valerio; Walters, Adam

    2009-01-01

    Two hundred and fifty-one 12 C 2 D 2 transitions have been measured in the 0.2-1.6 THz region of its ν 5 -ν 4 difference band and 202 of them were observed for the first time. The accuracy of these measurements is estimated to be ranging from 50 kHz to 100 kHz. The 12 C 2 D 2 molecules were generated under room temperature by passing 120-150 mTorr D 2 O vapor through calcium carbide (CaC 2 ) powder. A multistate analysis was carried out for the bending vibrational modes ν 4 and ν 5 of 12 C 2 D 2 , which includes the lines observed in this work and prior microwave, far-infrared and infrared data on the pure bending levels. Significantly improved molecular parameters were obtained for 12 C 2 D 2 by adding the new measurements to the old data set, which had only 10 lines with microwave measurement precision. New frequency and intensity predictions have been made based on the obtained molecular parameters. The more precise measurements and new predictions reported here will support the analyses of astronomical observations by the future high-resolution spectroscopy telescopes such as Herschel, SOFIA, and ALMA, which will work in the terahertz spectral region.

  8. Charge generation in organic solar cell materials studied by terahertz spectroscopy

    KAUST Repository

    Scarongella, M.

    2015-09-09

    We have investigated the photophysics in neat films of conjugated polymer PBDTTPD and its blend with PCBM using terahertz time-domain spectroscopy. This material has very high efficiency when used in organic solar cells. We were able to identify a THz signature for bound excitons in neat PBDTTPD films, pointing to important delocalization in those excitons. Then, we investigated the nature and local mobility (orders of magnitude higher than bulk mobility) of charges in the PBDTTPPD:PCBM blend as a function of excitation wavelength, fluence and pump-probe time delay. At low pump fluence (no bimolecular recombination phenomena), we were able to observe prompt and delayed charge generation components, the latter originating from excitons created in neat polymer domains which, thanks to delocalization, could reach the PCBM interface and dissociate to charges on a time scale of 1 ps. The nature of the photogenerated charges did not change between 0.5 ps and 800 ps after photo-excitation, which indicated that the excitons split directly into relatively free charges on an ultrafast time scale. © (2015) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.

  9. Observing the temperature dependent transition of the GP2 peptide using terahertz spectroscopy.

    Directory of Open Access Journals (Sweden)

    Yiwen Sun

    Full Text Available The GP2 peptide is derived from the Human Epidermal growth factor Receptor 2 (HER2/nue, a marker protein for breast cancer present in saliva. In this paper we study the temperature dependent behavior of hydrated GP2 at terahertz frequencies and find that the peptide undergoes a dynamic transition between 200 and 220 K. By fitting suitable molecular models to the frequency response we determine the molecular processes involved above and below the transition temperature (T(D. In particular, we show that below T(D the dynamic transition is dominated by a simple harmonic vibration with a slow and temperature dependent relaxation time constant and that above T(D, the dynamic behavior is governed by two oscillators, one of which has a fast and temperature independent relaxation time constant and the other of which is a heavily damped oscillator with a slow and temperature dependent time constant. Furthermore a red shifting of the characteristic frequency of the damped oscillator was observed, confirming the presence of a non-harmonic vibration potential. Our measurements and modeling of GP2 highlight the unique capabilities of THz spectroscopy for protein characterization.

  10. Low Energy Spectrum of Proximate Kitaev Spin Liquid α -RuCl3 by Terahertz Spectroscopy

    Science.gov (United States)

    Little, Arielle; Wu, Liang; Kelley, Paige; Banerjee, Arnab; Bridges, Craig; Yan, Jiaqiang; Nagler, Stephen; Mandrus, David; Orenstein, Joseph

    A Quantum Spin Liquid (QSL) is an ultra-quantum state of matter with no ordered ground state. Recently, a route to a QSL identified by Kitaev has received a great deal of attention. The compound α -RuCl3, in which Ru atoms form a honeycomb lattice, has been shown to possess Kitaev exchange interactions, although a smaller Heisenberg interaction exists and leads to a zig-zag antiferromagnetic state below 7 K. Because of proximity to the exactly-solvable Kitaev spin-liquid model, this material is considered a potential host for Majorana-like modes. In this work, we use time-domain terahertz (THz) Spectroscopy to probe the low-energy excitations of α -RuCl3. We observe the emergence of a sharp magnetic spin-wave absorption peak below the AFM ordering temperature at 7 K on top of a broad continuum that persists up to room temperature. Additionally we report the polarization dependence of the THz absorption, which reveals optical birefringence, indicating the presence of large monoclinic domains.

  11. Resolving the Origins of Crystalline Anharmonicity Using Terahertz Time-Domain Spectroscopy and ab Initio Simulations.

    Science.gov (United States)

    Ruggiero, Michael T; Zeitler, J Axel

    2016-11-17

    Anharmonicity has been shown to be an important piece of the fundamental framework that dictates numerous observable phenomena. In particular, anharmonicity is the driving force of vibrational relaxation processes, mechanisms that are integral to the proper function of numerous chemical processes. However, elucidating its origins has proven difficult due to experimental and theoretical challenges, specifically related to separating the anharmonic contributions from other unrelated effects. While no one technique is particularly suited for providing a complete picture of anharmonicity, by combining multiple complementary methods such a characterization can be made. In this study the role of individual atomic interactions on the anharmonic properties of crystalline purine, the building block of many DNA and RNA nucleobases, is studied by experimental terahertz time-domain spectroscopy and first-principles density functional theory (DFT) and ab initio molecular dynamics simulations (AIMD). In particular, the detailed vibrational information provided by the DFT calculations is used to interpret the atomic origins of anharmonic-related effects as determined by the AIMD calculations, which are in good agreement with the experimental data. The results highlight that anharmonicity is especially pronounced in the intermolecular interactions, particularly along the amine hydrogen bond coordinate, and yields valuable insight into what is similarly observed complex biosystems and crystalline solids.

  12. Comparative study of boson peak in normal and secondary alcohols with terahertz time-domain spectroscopy

    International Nuclear Information System (INIS)

    Yomogida, Yoshiki; Sato, Yuki; Nozaki, Ryusuke; Mishina, Tomobumi; Nakahara, Jun'ichiro

    2010-01-01

    Using terahertz (THz) time-domain spectroscopy, we measured the complex permittivity of some normal (1-propanol, 1-butanol, and 1-pentanol) and secondary alcohols (2-propanol, 2-butanol, and 2-pentanol) in the frequency ranges from 0.2 to 2.5 THz at temperatures from 253 to 323 K. For all the samples, the complex permittivity in the THz region includes the following three components: (i) a high frequency side of dielectric relaxation processes, (ii) a broad mode around 1 THz, and (iii) a low frequency side of an intermolecular vibration mode located above 2.5 THz. The mode around 1 THz is recognized as a boson peak which is related to the local structure of disordered materials. The intensity of the boson peak in secondary alcohols is higher than that in normal alcohols. On the other hand, the number of carbon atoms slightly affects the appearance of the boson peak. These observations indicate that the position of an OH group in a molecule has a profound effect on the local structures in monohydric alcohols.

  13. Terahertz-infrared spectroscopy of overdoped manganites La.sub.1-x./sub.Ca.sub.x./sub.MnO.sub.3./sub

    Czech Academy of Sciences Publication Activity Database

    Kadyrov, L.S.; Zhukova, E.S.; Torgashev, V. I.; Gorshunov, B. P.; Prokhorov, A. S.; Motovilova, E.A.; Fischgrabe, F.; Moshnyaga, V.; Zhang, T.; Kremer, R.; Pracht, U.; Zapf, S.; Pokorný, Jan; Untereiner, G.; Kamba, Stanislav; Dressel, M.

    2015-01-01

    Roč. 460, SI (2015), s. 199-201 ISSN 0921-4526 R&D Projects: GA ČR GAP204/12/1163 Institutional support: RVO:68378271 Keywords : manganites * terahertz spectroscopy * Raman spectroscopy Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.352, year: 2015

  14. Terahertz cyclotron resonance spectroscopy of an AlGaN/GaN heterostructure using a high-field pulsed magnet and an asynchronous optical sampling technique

    International Nuclear Information System (INIS)

    Spencer, B. F.; Smith, W. F.; Hibberd, M. T.; Dawson, P.; Graham, D. M.; Beck, M.; Bartels, A.; Guiney, I.; Humphreys, C. J.

    2016-01-01

    The effective mass, sheet carrier concentration, and mobility of electrons within a two-dimensional electron gas in an AlGaN/GaN heterostructure were determined using a laboratory-based terahertz cyclotron resonance spectrometer. The ability to perform terahertz cyclotron resonance spectroscopy with magnetic fields of up to 31 T was enabled by combining a high-field pulsed magnet with a modified asynchronous optical sampling terahertz detection scheme. This scheme allowed around 100 transmitted terahertz waveforms to be recorded over the 14 ms magnetic field pulse duration. The sheet density and mobility were measured to be 8.0 × 10 12  cm −2 and 9000 cm 2 V −1  s −1 at 77 K. The in-plane electron effective mass at the band edge was determined to be 0.228 ± 0.002m 0 .

  15. Reflection terahertz time-domain imaging for analysis of an 18th century neoclassical easel painting

    DEFF Research Database (Denmark)

    Dandolo, Corinna Ludovica Koch; Filtenborg, Troels; Fukunaga, Kaori

    2015-01-01

    Terahertz time-domain imaging (THz-TDI) has been applied for imaging a hidden portrait and other subsurfacecomposition layers of an 18th century (18C) easel painting by Nicolai Abildgaard, the most important 18CDanish neoclassical painter of historical and mythological subjects. For the first time...

  16. Fast and non-destructive pore structure analysis using terahertz time-domain spectroscopy.

    Science.gov (United States)

    Markl, Daniel; Bawuah, Prince; Ridgway, Cathy; van den Ban, Sander; Goodwin, Daniel J; Ketolainen, Jarkko; Gane, Patrick; Peiponen, Kai-Erik; Zeitler, J Axel

    2018-02-15

    Pharmaceutical tablets are typically manufactured by the uni-axial compaction of powder that is confined radially by a rigid die. The directional nature of the compaction process yields not only anisotropic mechanical properties (e.g. tensile strength) but also directional properties of the pore structure in the porous compact. This study derives a new quantitative parameter, S a , to describe the anisotropy in pore structure of pharmaceutical tablets based on terahertz time-domain spectroscopy measurements. The S a parameter analysis was applied to three different data sets including tablets with only one excipient (functionalised calcium carbonate), samples with one excipient (microcrystalline cellulose) and one drug (indomethacin), and a complex formulation (granulated product comprising several excipients and one drug). The overall porosity, tablet thickness, initial particle size distribution as well as the granule density were all found to affect the significant structural anisotropies that were observed in all investigated tablets. The S a parameter provides new insights into the microstructure of a tablet and its potential was particularly demonstrated for the analysis of formulations comprising several components. The results clearly indicate that material attributes, such as particle size and granule density, cause a change of the pore structure, which, therefore, directly impacts the liquid imbibition that is part of the disintegration process. We show, for the first time, how the granule density impacts the pore structure, which will also affect the performance of the tablet. It is thus of great importance to gain a better understanding of the relationship of the physical properties of material attributes (e.g. intragranular porosity, particle shape), the compaction process and the microstructure of the finished product. Copyright © 2017 Elsevier B.V. All rights reserved.

  17. Doping profile measurements in silicon using terahertz time domain spectroscopy (THz-TDS) via electrochemical anodic oxidation

    Science.gov (United States)

    Tulsyan, Gaurav

    Doping profiles are engineered to manipulate device properties and to determine electrical performances of microelectronic devices frequently. To support engineering studies afterward, essential information is usually required from physically characterized doping profiles. Secondary Ion Mass Spectrometry (SIMS), Spreading Resistance Profiling (SRP) and Electrochemical Capacitance Voltage (ECV) profiling are standard techniques for now to map profile. SIMS yields a chemical doping profile via ion sputtering process and owns a better resolution, whereas ECV and SRP produce an electrical doping profile detecting free carriers in microelectronic devices. The major difference between electrical and chemical doping profiles is at heavily doped regions greater than 1020 atoms/cm3. At the profile region over the solubility limit, inactive dopants induce a flat plateau and detected by electrical measurements only. Destructive techniques are usually designed as stand-alone systems to study impurities. For an in-situ process control purpose, non-contact methods, such as ellipsometry and non-contact capacitance voltage (CV) techniques are current under development. In this theses work, terahertz time domain spectroscopy (THz-TDS) is utilized to achieve electrical doping profile in both destructive and non-contact manners. In recent years the Terahertz group at Rochester Institute Technology developed several techniques that use terahertz pulses to non-destructively map doping profiles. In this thesis, we study a destructive but potentially higher resolution version of the terahertz based approach to map the profile of activated dopants and augment the non-destructive approaches already developed. The basic idea of the profile mapping approach developed in this MS thesis is to anodize, and thus oxidize to silicon dioxide, thin layers (down to below 10 nm) of the wafer with the doping profile to be mapped. Since the dopants atoms and any free carriers in the silicon oxide thin

  18. Characteristic responses of biological and nanoscale systems in the terahertz frequency range

    Energy Technology Data Exchange (ETDEWEB)

    Angeluts, A A; Balakin, A V; Evdokimov, M G; Ozheredov, I A; Sapozhnikov, D A; Solyankin, P M; Shkurinov, A P [International Laser Center, M. V. Lomonosov Moscow State University, Moscow (Russian Federation); Esaulkov, M N; Nazarov, M M [Institute on Laser and Information Technologies, Russian Academy of Sciences, Shatura, Moscow Region (Russian Federation); Cherkasova, O P [Institute of Laser Physics, Siberian Branch, Russian Academy of Sciences, Novosibirsk (Russian Federation)

    2014-07-31

    This paper briefly examines methods for the generation of pulsed terahertz radiation and principles of pulsed terahertz spectroscopy, an advanced informative method for studies of complex biological and nanostructured systems. Some of its practical applications are described. Using a number of steroid hormones as examples, we demonstrate that terahertz spectroscopy in combination with molecular dynamics methods and computer simulation allows one to gain information about the structure of molecules in crystals. A 'terahertz colour vision' method is proposed for analysis of pulsed terahertz signals reflected from biological tissues and it is shown that this method can be effectively used to analyse the properties of biological tissues and for early skin cancer diagnosis. (laser biophotonics)

  19. Quantitative Identification of the Annealing Degree of Apatite Fission Tracks Using Terahertz Time Domain Spectroscopy (THz-TDS).

    Science.gov (United States)

    Wu, Hang; Wu, Shixiang; Qiu, Nansheng; Chang, Jian; Bao, Rima; Zhang, Xin; Liu, Nian; Liu, Shuai

    2018-01-01

    Apatite fission-track (AFT) analysis, a widely used low-temperature thermochronology method, can provide details of the hydrocarbon generation history of source rocks for use in hydrocarbon exploration. The AFT method is based on the annealing behavior of fission tracks generated by 238 U fission in apatite particles during geological history. Due to the cumbersome experimental steps and high expense, it is imperative to find an efficient and inexpensive technique to determinate the annealing degree of AFT. In this study, on the basis of the ellipsoid configuration of tracks, the track volume fraction model (TVFM) is established and the fission-track volume index is proposed. Furthermore, terahertz time domain spectroscopy (THz-TDS) is used for the first time to identify the variation of the AFT annealing degree of Durango apatite particles heated at 20, 275, 300, 325, 450, and 500 ℃ for 10 h. The THz absorbance of the sample increases with the degree of annealing. In addition, the THz absorption index is exponentially related to annealing temperature and can be used to characterize the fission-track volume index. Terahertz time domain spectroscopy can be an ancillary technique for AFT thermochronological research. More work is urgently needed to extrapolate experimental data to geological conditions.

  20. Picosecond Transient Photoconductivity in Functionalized Pentacene Molecular Crystals Probed by Terahertz Pulse Spectroscopy

    Science.gov (United States)

    Hegmann, F. A.; Tykwinski, R. R.; Lui, K. P.; Bullock, J. E.; Anthony, J. E.

    2002-11-01

    We have measured transient photoconductivity in functionalized pentacene molecular crystals using ultrafast optical pump-terahertz probe techniques. The single crystal samples were excited using 800nm, 100fs pulses, and the change in transmission of time-delayed, subpicosecond terahertz pulses was used to probe the photoconducting state over a temperature range from 10 to 300K. A subpicosecond rise in photoconductivity is observed, suggesting that mobile carriers are a primary photoexcitation. At times longer than 4ps, a power-law decay is observed consistent with dispersive transport.

  1. Mid infrared upconversion spectroscopy using diffuse reflectance

    DEFF Research Database (Denmark)

    Sanders, Nicolai Højer; Kehlet, Louis M.; Dam, Jeppe Seidelin

    2014-01-01

    specifically that upconversion methods can be deployed using a diffuse reflectance setup where the test sample is irradiated by a thermal light source, i.e. a globar. The diffuse reflectance geometry is particularly well suited when a transmission setup cannot be used. This situation may happen for highly...

  2. Spectroscopic study of Alzheimer's amyloid fibrils using terahertz time domain spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Jung, Euna; Kim, Jeonghoi; Han, Younho; Moon, Kiwon; Lim, Meehyun; Han, Haewook; Park, Joonhyuck; Kim, Sungjee [POSTECH, Pohang (Korea, Republic of)

    2008-11-15

    Alzheimer's disease, one of the most common neurodegenerative diseases, is characterized by extensive amyloid deposition. Amyloid deposits contain the abundant fibrils formed by amyloid β protein (Aβ). Because amyloid fibrils are associated with amyloid diseases, including Alzheimer's disease, type 2 diabetes, prion disease, Parkinson's disease, senile systemic amyloidosis and Huntington's disease, there has been considerable interest within the biomedical and biochemical research communities. In transmission electron microscopic (TEM)images, amyloid firils are 0.1∼10μm long and approximately 10nm wide. Amyloid fibrils commonly exhibit self assembled filaments, often described as twisted or parallel assemblies of finer protofilaments. They are formed by the spontaneous aggregation of a wide variety of peptides and proteins. Structural studies of amyloid fibrils have revealed that the common structural motif of virtually all amyloid fibrils consists of cross β sheets in which the peptide strands are arranged perpendicular to the long axis of the fiber. But little was known until recently about the molecular level structures of amyloid fibils. Therefore, spectroscopic investigation of both amyloid fibrils and Aβ at the molecular level can provide the significant evidence for the molecular understanding of amyloidogenesis and for the development of innovative therapeutic and diagnostic approaches. We used terahertz time domain spectroscopy (THz TDS)to investigate both Aβ and amyloid fibril. THz TDS, developed over the last two decades, is a powerful tool to extract the properties of biomaterials and provides unique spectral signatures of biomolecules within 0.1∼10THz, which exists between microwave and infrared frequency range. Current interest in THz radiation arises from its capability of probing the delocalized collective vibrational modes in proteins. Studying the collective modes of proteins in THz frequency range can play an

  3. Spectroscopic study of Alzheimer's amyloid fibrils using terahertz time domain spectroscopy

    International Nuclear Information System (INIS)

    Jung, Euna; Kim, Jeonghoi; Han, Younho; Moon, Kiwon; Lim, Meehyun; Han, Haewook; Park, Joonhyuck; Kim, Sungjee

    2008-01-01

    Alzheimer's disease, one of the most common neurodegenerative diseases, is characterized by extensive amyloid deposition. Amyloid deposits contain the abundant fibrils formed by amyloid β protein (Aβ). Because amyloid fibrils are associated with amyloid diseases, including Alzheimer's disease, type 2 diabetes, prion disease, Parkinson's disease, senile systemic amyloidosis and Huntington's disease, there has been considerable interest within the biomedical and biochemical research communities. In transmission electron microscopic (TEM)images, amyloid firils are 0.1∼10μm long and approximately 10nm wide. Amyloid fibrils commonly exhibit self assembled filaments, often described as twisted or parallel assemblies of finer protofilaments. They are formed by the spontaneous aggregation of a wide variety of peptides and proteins. Structural studies of amyloid fibrils have revealed that the common structural motif of virtually all amyloid fibrils consists of cross β sheets in which the peptide strands are arranged perpendicular to the long axis of the fiber. But little was known until recently about the molecular level structures of amyloid fibils. Therefore, spectroscopic investigation of both amyloid fibrils and Aβ at the molecular level can provide the significant evidence for the molecular understanding of amyloidogenesis and for the development of innovative therapeutic and diagnostic approaches. We used terahertz time domain spectroscopy (THz TDS)to investigate both Aβ and amyloid fibril. THz TDS, developed over the last two decades, is a powerful tool to extract the properties of biomaterials and provides unique spectral signatures of biomolecules within 0.1∼10THz, which exists between microwave and infrared frequency range. Current interest in THz radiation arises from its capability of probing the delocalized collective vibrational modes in proteins. Studying the collective modes of proteins in THz frequency range can play an important role in

  4. Assessing skin hydration status in haemodialysis patients using terahertz spectroscopy: a pilot / feasibility study

    Czech Academy of Sciences Publication Activity Database

    Kadlec, Filip; Berta, Milan; Kužel, Petr; Lopot, F.; Polakovič, V.

    2008-01-01

    Roč. 53, č. 24 (2008), 7063-7071 ISSN 0031-9155 R&D Projects: GA MŠk LC512 Institutional research plan: CEZ:AV0Z10100520 Keywords : terahertz radiation * haemodialysis * skin turgor * epidermis Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.784, year: 2008

  5. Time-resolved terahertz spectroscopy in a parallel-plate waveguide

    DEFF Research Database (Denmark)

    Cooke, David; Jepsen, Peter Uhd

    2009-01-01

    The parallel plate waveguide (PPWG), formed by two conducting parallel plates separated by a distance on the order of the wavelength of the propagating light, has shown itself to be a near ideal terahertz interconnect exhibiting low loss and dispersionless propagation.[1] It is also a useful tool...

  6. Terahertz Frequency-Domain Spectroscopy of Low-Pressure Acetonitrile Gas by a Photomixing Terahertz Synthesizer Referenced to Dual Optical Frequency Combs

    Science.gov (United States)

    Hsieh, Yi-Da; Kimura, Hiroto; Hayashi, Kenta; Minamikawa, Takeo; Mizutani, Yasuhiro; Yamamoto, Hirotsugu; Iwata, Tetsuo; Inaba, Hajime; Minoshima, Kaoru; Hindle, Francis; Yasui, Takeshi

    2016-09-01

    A terahertz (THz) frequency synthesizer based on photomixing of two near-infrared lasers with a sub-THz to THz frequency offset is a powerful tool for spectroscopy of polar gas molecules due to its broad spectral coverage; however, its frequency accuracy and resolution are relatively low. To tune the output frequency continuously and widely while maintaining its traceability to a frequency standard, we developed a photomixing THz synthesizer phase-locked to dual optical frequency combs (OFCs). While the phase-locking to dual OFCs ensured continuous tuning within a spectral range of 120 GHz, in addition to the traceability to the frequency standard, use of a broadband uni-traveling carrier photodiode for photomixing enabled the generation of CW-THz radiation within a frequency range from 0.2 to 1.5 THz. We demonstrated THz frequency-domain spectroscopy of gas-phase acetonitrile CH3CN and its isotope CH3 13CN in the frequency range of 0.600-0.720 THz using this THz synthesizer. Their rotational transitions were assigned with a frequency accuracy of 8.42 × 10-8 and a frequency resolution of 520 kHz. Furthermore, the concentration of the CH3CN gas at 20 Pa was determined to be (5.41 ± 0.05) × 1014 molecules/cm3 by curve fitting analysis of the measured absorbance spectrum, and the mixture ratio of the mixed CH3CN/CH3 13CN gas was determined to be 1:2.26 with a gas concentration of 1014-1015 molecules/cm3. The developed THz synthesizer is highly promising for high-precision THz-FDS of low-pressure molecular gases and will enable the qualitative and quantitative analyses of multiple gases.

  7. Fabrication of photonic amorphous diamonds for terahertz-wave applications

    Energy Technology Data Exchange (ETDEWEB)

    Komiyama, Yuichiro; Abe, Hiroyuki; Kamimura, Yasushi; Edagawa, Keiichi, E-mail: edagawa@iis.u-tokyo.ac.jp [Institute of Industrial Science, The University of Tokyo, Komaba, Meguro-ku, Tokyo 153-8505 (Japan)

    2016-05-09

    A recently proposed photonic bandgap material, named “photonic amorphous diamond” (PAD), was fabricated in a terahertz regime, and its terahertz-wave propagation properties were investigated. The PAD structure was fabricated from acrylic resin mixed with alumina powder, using laser lithographic, micro-additive manufacturing technique. After fabrication, the resulting structure was dewaxed and sintered. The formation of a photonic bandgap at around 0.45 THz was demonstrated by terahertz time-domain spectroscopy. Reflecting the disordered nature of the random network structure, diffusive terahertz-wave propagation was observed in the passbands; the scattering mean-free path decreased as the frequency approached the band edge. The mean-free paths evaluated at the band edges were close to the Ioffe-Regel threshold value for wave localization.

  8. Using reflectance spectroscopy to predict beef tenderness.

    Science.gov (United States)

    Bowling, M B; Vote, D J; Belk, K E; Scanga, J A; Tatum, J D; Smith, G C

    2009-05-01

    A study was conducted to determine if reflectance measurements made in the near-infrared region of the spectrum were additive to reflectance measurements made in the visible region of the spectrum for predicting Warner-Bratzler shear force (WBSF) values. Eighty seven strip loins were collected following fabrication over 3d at a commercial beef processing facility from heifer carcasses with Slight or Traces marbling scores. Spectroscopic measurements were made at approximately 50h postmortem using a Hunter-Lab UltraScan. Subsequently, all strip loins were aged for 14d, cooked to an internal temperature of 70°C, and sheared to obtain WBSF values. Reflectance measurements obtained in the near-infrared region of the spectrum were correlated with WBSF values, however, these measurements were not additive to the predictive ability of reflectance measurements (R(2) values did not differ) made in the visible portion of the spectrum when the use of broad-band wavelength filters were simulated. It was therefore determined, that both the visible and near-infrared spectra measure reflectance and that both methods are acceptable methods of tenderness prediction.

  9. Terahertz time-domain spectroscopy response of amines and amino acids intercalated smectites in far-infrared region

    Energy Technology Data Exchange (ETDEWEB)

    Janek, M., E-mail: marian.janek@fns.uniba.sk [Comenius University, Faculty of Natural Sciences, Department of Physical and Theoretical Chemistry, Mlynská dolina CH1, SK-84215 Bratislava (Slovakia); Zich, D. [Comenius University, Faculty of Natural Sciences, Department of Physical and Theoretical Chemistry, Mlynská dolina CH1, SK-84215 Bratislava (Slovakia); Naftaly, M., E-mail: mira.naftaly@npl.co.uk [National Physical Laboratory, Hampton Rd, Teddington, Middlesex TW11 0LW (United Kingdom)

    2014-06-01

    Layered clay minerals from the smectite group with different chemical composition and resulting layer charge (e.g. pyrophyllite, illite, hectorite and montmorillonite) were characterised for their dielectric properties in the far-infrared region using terahertz-time domain spectroscopy (THz-TDS). Samples with distinct cation exchange capacity such as hectorite and montmorillonite were modified using cation exchange reaction with alkylamines or amino acids. The presence of these species in 2D gallery was proved by X-ray diffraction and Fourier transform infrared spectroscopy. The frequency-dependent refractive index of these minerals was determined in the experimentally accessible range of 0.1–3.0 THz (3–100 cm{sup −1}) using THz-TDS. Pristine samples revealed their refractive indices to be 1.82–2.15 at about 1 THz while the modified montmorillonite samples had their refractive indices changed by organic molecules used for their modification to 1.70–2.35 for amines and 1.97–2.36 for amino acids. The presence of organic substances in 2D gallery of clays was detectable despite the relatively high absorption of smectites with magnitude of 100 cm{sup −1}. - Graphical abstract: Display Omitted - Highlights: • “Guest” molecules in “host” layered material were investigated. • Amines and amino-acids were selected as guest molecules. • Natural and synthetic host with smectite phyllosilicate structure were used. • Dielectric properties were investigated by terahertz time domain spectroscopy. • Resonance absorption peaks of guest were detected in far infrared region.

  10. Ultrafast terahertz spectroscopy study of a Kondo insulating thin-film Sm B6 : Evidence for an emergent surface state

    Science.gov (United States)

    Zhang, Jingdi; Yong, Jie; Takeuchi, Ichiro; Greene, Richard L.; Averitt, Richard D.

    2018-04-01

    We utilize terahertz time domain spectroscopy to investigate thin films of the heavy fermion compound Sm B6 , a prototype Kondo insulator. Temperature-dependent terahertz (THz) conductivity measurements reveal a rapid decrease in the Drude weight and carrier scattering rate at ˜T*=20 K , well below the hybridization gap onset temperature (100 K). Moreover, a low-temperature conductivity plateau (below 20 K) suggests the emergence of a surface state with an effective electron mass of 0.1 me . The conductivity dynamics following optical excitation is also measured and interpreted using Rothwarf-Taylor (R-T) phenomenology, yielding a hybridization gap energy of 17 meV. However, R-T modeling of the conductivity dynamics reveals a deviation from the expected thermally excited quasiparticle density at temperatures below 20 K, indicative of another channel opening up in the low-energy electrodynamics. Taken together, these results are consistent with the onset of a surface state well below the crossover temperature (100 K) after long-range coherence of the f -electron Kondo lattice is established.

  11. Nondestructive evaluation of crystallized-particle size in lactose-powder by terahertz time-domain spectroscopy

    Science.gov (United States)

    Yamauchi, Satoshi; Hatakeyama, Sakura; Imai, Yoh; Tonouchi, Masayoshi

    2014-03-01

    Transmission-type terahertz time-domain spectroscopy is applied to evaluate crystallized lactose particle of size below 30 μm, which is far too small compared to the wavelength of incident terahertz (THz)-wave. The THz-absorption spectrum of lactose is successfully deconvoluted by Lorentzian to two spectra with peaks at 17.1 cm-1 (0.53 THz) and 45.6 cm-1 (1.37 THz) derived from α-lactose monohydrate, and a spectrum at 39.7 cm-1 (1.19 THz) from anhydrous β-lactose after removal of the broad-band spectrum by polynomial cubic function. Lactose is mainly crystallized into α-lactose monohydrate from the supersaturated solution at room temperature with a small amount of anhydrous β-lactose below 4%. The absorption feature is dependent on the crystallized particle size and the integrated intensity ratio of the two absorptions due to α-lactose monohydrate is correlated in linear for the size.

  12. Ultra-wideband high-efficiency reflective linear-to-circular polarization converter based on metasurface at terahertz frequencies.

    Science.gov (United States)

    Jiang, Yannan; Wang, Lei; Wang, Jiao; Akwuruoha, Charles Nwakanma; Cao, Weiping

    2017-10-30

    The polarization conversion of electromagnetic (EM) waves, especially linear-to-circular (LTC) polarization conversion, is of great significance in practical applications. In this study, we propose an ultra-wideband high-efficiency reflective LTC polarization converter based on a metasurface in the terahertz regime. It consists of periodic unit cells, each cell of which is formed by a double split resonant square ring, dielectric layer, and fully reflective gold mirror. In the frequency range of 0.60 - 1.41 THz, the magnitudes of the reflection coefficients reach approximately 0.7, and the phase difference between the two orthogonal electric field components of the reflected wave is close to 90° or -270°. The results indicate that the relative bandwidth reaches 80% and the efficiency is greater than 88%, thus, ultra-wideband high-efficiency LTC polarization conversion has been realized. Finally, the physical mechanism of the polarization conversion is revealed. This converter has potential applications in antenna design, EM measurement, and stealth technology.

  13. Forensic applications of microscopical infrared internal reflection spectroscopy

    Science.gov (United States)

    Tungol, Mary W.; Bartick, Edward G.; Reffner, John A.

    1994-01-01

    Applications of microscopical infrared internal reflection spectroscopy in forensic science are discussed. Internal reflection spectra of single fibers, hairs, paint chips, vehicle rubber bumpers, photocopy toners, carbon copies, writing ink on paper, lipstick on tissue, black electrical tape, and other types of forensic evidence have been obtained. The technique is convenient, non-destructive, and may permit smeared materials to be analyzed in situ.

  14. Photoionization of atmospheric gases studied by time-resolved terahertz spectroscopy

    Czech Academy of Sciences Publication Activity Database

    Mics, Zoltan; Kužel, Petr; Jungwirth, Pavel; Bradforth, S. E.

    2008-01-01

    Roč. 465, 1-3 (2008), s. 20-24 ISSN 0009-2614 R&D Projects: GA MŠk LC512; GA ČR(CZ) GA202/06/0286 Institutional research plan: CEZ:AV0Z10100520; CEZ:AV0Z40550506 Keywords : terahertz * pump -probe * atmospheric gases * photoionization * plasma Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.169, year: 2008

  15. Ultrafast carrier dynamics in microcrystalline silicon probed by time-resolved terahertz spectroscopy

    Czech Academy of Sciences Publication Activity Database

    Fekete, Ladislav; Kužel, Petr; Němec, Hynek; Kadlec, Filip; Deyneka, Alexander; Stuchlík, Jiří; Fejfar, Antonín

    2009-01-01

    Roč. 79, č. 11 (2009), 115306/1-115306/13 ISSN 1098-0121 R&D Projects: GA MŠk(CZ) LC06040; GA AV ČR(CZ) IAA100100902 Institutional research plan: CEZ:AV0Z10100520; CEZ:AV0Z10100521 Keywords : microcrystalline silicon * amorphous silicon * terahertz * ultrafast * photoconductivity Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.475, year: 2009

  16. Fast and non-destructive pore structure analysis using terahertz time-domain spectroscopy.

    OpenAIRE

    Markl, Daniel; Bawuah, Prince; Ridgway, Cathy; van den Ban, Sander; Goodwin, Daniel J; Ketolainen, Jarkko; Gane, Patrick; Peiponen, Kai-Erik; Zeitler, Jochen Axel

    2018-01-01

    Pharmaceutical tablets are typically manufactured by the uni-axial compaction of powder that is confined radially by a rigid die. The directional nature of the compaction process yields not only anisotropic mechanical properties (e.g. tensile strength) but also directional properties of the pore structure in the porous compact. This study derives a new quantitative parameter, $S_a$, to describe the anisotropy in pore structure of pharmaceutical tablets based on terahertz time-domain spectrosc...

  17. Fabrication of Terahertz Wave Resonators with Alumina Diamond Photonic Crystals for Frequency Amplification in Water Solvents

    International Nuclear Information System (INIS)

    Ohta, N; Niki, T; Kirihara, S

    2011-01-01

    Terahertz wave resonators composed of alumina photonic crystals with diamond lattice structures were designed and fabricated by using micro stereolithography. These three dimensional periodic structures can reflect perfectly electromagnetic waves through Bragg diffraction. A micro glass cell including water solutions was put between the photonic crystals as a novel resonance sensor with terahertz frequency range. The localized and amplified waves in the resonators were measured by a spectroscopy, and visualized by theoretical simulations.

  18. Band Transport and Trapping in Didodecyl[1]benzothieno[3,2-b][1]benzothiophene Probed by Terahertz Spectroscopy.

    Science.gov (United States)

    Arend, Thomas R; Wimmer, Andreas; Schweicher, Guillaume; Chattopadhyay, Basab; Geerts, Yves H; Kersting, Roland

    2017-11-02

    Terahertz electromodulation spectroscopy provides insight into the material-inherent transport properties of charge carriers in organic semiconductors. Experiments on didodecyl[1]benzothieno[3,2-b][1]benzothiophene (C 12 -BTBT-C 12 ) devices yield for holes an intraband mobility of 9 cm 2 V -1 s -1 . The short duration of the THz pulses advances the understanding of the hole transport on the molecular scale. The efficient screening of Coulomb potentials leads to a collective response of the hole gas to external fields, which can be well described by the Drude model. Bias stress of the devices generates deep traps that capture mobile holes. Although the resulting polarization across the device hinders the injection of mobile holes, the hole mobilities are not affected.

  19. Wavelength Selection Method Based on Differential Evolution for Precise Quantitative Analysis Using Terahertz Time-Domain Spectroscopy.

    Science.gov (United States)

    Li, Zhi; Chen, Weidong; Lian, Feiyu; Ge, Hongyi; Guan, Aihong

    2017-12-01

    Quantitative analysis of component mixtures is an important application of terahertz time-domain spectroscopy (THz-TDS) and has attracted broad interest in recent research. Although the accuracy of quantitative analysis using THz-TDS is affected by a host of factors, wavelength selection from the sample's THz absorption spectrum is the most crucial component. The raw spectrum consists of signals from the sample and scattering and other random disturbances that can critically influence the quantitative accuracy. For precise quantitative analysis using THz-TDS, the signal from the sample needs to be retained while the scattering and other noise sources are eliminated. In this paper, a novel wavelength selection method based on differential evolution (DE) is investigated. By performing quantitative experiments on a series of binary amino acid mixtures using THz-TDS, we demonstrate the efficacy of the DE-based wavelength selection method, which yields an error rate below 5%.

  20. Invited Article: An active terahertz polarization converter employing vanadium dioxide and a metal wire grating in total internal reflection geometry

    Science.gov (United States)

    Liu, Xudong; Chen, Xuequan; Parrott, Edward P. J.; Han, Chunrui; Humbert, Georges; Crunteanu, Aurelian; Pickwell-MacPherson, Emma

    2018-05-01

    Active broadband terahertz (THz) polarization manipulation devices are challenging to realize, but also of great demand in broadband terahertz systems. Vanadium dioxide (VO2) shows a promising phase transition for active control of THz waves and provides broadband polarization characteristics when integrated within grating-type structures. We creatively combine a VO2-based grating structure with a total internal reflection (TIR) geometry providing a novel interaction mechanism between the electromagnetic waves and the device, to realize a powerful active broadband THz polarization-controlling device. The device is based on a Si-substrate coated with a VO2 layer and a metal grating structure on top, attached to a prism for generating the TIR condition on the Si-VO2-grating interface. The grating is connected to electrodes for electrically switching the VO2 between its insulating and conducting phases. By properly selecting the incident angle of the THz waves, the grating direction, and the incident polarization state, we first achieved a broadband intensity modulator under a fused silica prism with an average modulation depth of 99.75% in the 0.2-1.1 THz region. Additionally, we realized an active ultra-broadband quarter-wave converter under a Si prism that can be switched between a 45° linear rotator and a quarter wave converter in the 0.8-1.5 THz region. This is the first demonstration of an active quarter-wave converter with ultra-broad bandwidth performance. Our work shows a highly flexible and multifunctional polarization-controlling device for broadband THz applications.

  1. Terahertz plasmonic Bessel beamformer

    International Nuclear Information System (INIS)

    Monnai, Yasuaki; Shinoda, Hiroyuki; Jahn, David; Koch, Martin; Withayachumnankul, Withawat

    2015-01-01

    We experimentally demonstrate terahertz Bessel beamforming based on the concept of plasmonics. The proposed planar structure is made of concentric metallic grooves with a subwavelength spacing that couple to a point source to create tightly confined surface waves or spoof surface plasmon polaritons. Concentric scatterers periodically incorporated at a wavelength scale allow for launching the surface waves into free space to define a Bessel beam. The Bessel beam defined at 0.29 THz has been characterized through terahertz time-domain spectroscopy. This approach is capable of generating Bessel beams with planar structures as opposed to bulky axicon lenses and can be readily integrated with solid-state terahertz sources

  2. The quantitative monitoring of mechanochemical reaction between solid L-tartaric acid and sodium carbonate monohydrate by terahertz spectroscopy

    Science.gov (United States)

    Liu, Xiaohong; Liu, Guifeng; Zhao, Hongwei; Zhang, Zengyang; Wei, Yongbo; Liu, Min; Wen, Wen; Zhou, Xingtai

    2011-11-01

    The solid-state reaction of chiral tartaric acid and alkali carbonate was studied by terahertz time-domain spectroscopy (THz-TDS). The sodium tartrate dihydrate was synthesized with high efficiency by mechanical grinding in the solid-state without waste that is particularly sustainable and environmentally benign. Distinct THz absorptions were observed for reactants and products. It indicates that THz spectroscopy is sensitive to different materials and crystal structures. The characteristic THz absorption peak at 1.09 THz of L (+)-Tartaric acid was selected for quantitative analysis. The reaction kinetics could be expressed by the Second-order equation and the Jander equation, which is consistent with a three-dimensional diffusion mechanism. The combination of multi-techniques including synchrotron radiation X-ray powder diffraction (SRXRPD), Fourier transform infrared (FT-IR) and scanning electron microscopy (SEM) was used to investigate the grinding process and presented supporting evidences. The results demonstrate that THz spectroscopy technique has great potential applications in process monitoring and analysis in pharmaceutical and chemical synthesis industry.

  3. Ultrashort Generation Regimes in the All-Fiber Kerr Mode-Locked Erbium-Doped Fiber Ring Laser for Terahertz Pulsed Spectroscopy

    Directory of Open Access Journals (Sweden)

    V. S. Voropaev

    2015-01-01

    Full Text Available Many femtosecond engineering applications require for a stable generation of ultrashort pulses. Thus, in the terahertz pulsed spectroscopy a measurement error in the refractive index is strongly dependent on the pulse duration stability with allowable variation of few femtoseconds. The aim of this work is to study the ultrashort pulses (USP regimes stability in the all – fiber erbium doped ring laser with Kerr mode-locking. The study was conducted at several different values of the total resonator intra-cavity dispersion. Three laser schemes with the intra-cavity dispersion values from -1.232 ps2 to +0.008 ps2 have been studied. In the experiment there were two regimes of generation observed: the stretched pulse generation and ordinary soliton generation. Main attention is focused on the stability of regimes under study. The most stable regime was that of the stretched pulse generation with a spectrum form of sech2 , possible pulse duration of 490 fs at least, repetition rate of 2.9 MHz, and average output power of 17 mW. It is worth noting, that obtained regimes had characteristics suitable for the successful use in the terahertz pulsed spectroscopy. The results may be useful in the following areas of science and technology: a high-precision spectroscopy, optical frequency standards, super-continuum generation, and terahertz pulsed spectroscopy. The future system development is expected to stabilize duration and repetition rate of the obtained regime of ultra-short pulse generation.

  4. Recognition of genetically modified product based on affinity propagation clustering and terahertz spectroscopy

    Science.gov (United States)

    Liu, Jianjun; Kan, Jianquan

    2018-04-01

    In this paper, based on the terahertz spectrum, a new identification method of genetically modified material by support vector machine (SVM) based on affinity propagation clustering is proposed. This algorithm mainly uses affinity propagation clustering algorithm to make cluster analysis and labeling on unlabeled training samples, and in the iterative process, the existing SVM training data are continuously updated, when establishing the identification model, it does not need to manually label the training samples, thus, the error caused by the human labeled samples is reduced, and the identification accuracy of the model is greatly improved.

  5. Total reflection X-ray photoelectron spectroscopy: A review

    International Nuclear Information System (INIS)

    Kawai, Jun

    2010-01-01

    Total reflection X-ray photoelectron spectroscopy (TRXPS) is reviewed and all the published papers on TRXPS until the end of 2009 are included. Special emphasis is on the historical development. Applications are also described for each report. The background reduction is the most important effect of total reflection, but interference effect, relation to inelastic mean free path, change of probing depth are also discussed.

  6. Carrier dynamics in silicon nanowires studied using optical-pump terahertz-probe spectroscopy

    Science.gov (United States)

    Beaudoin, Alexandre; Salem, Bassem; Baron, Thierry; Gentile, Pascal; Morris, Denis

    2014-03-01

    The advance of non-contact measurements involving pulsed terahertz radiation presents great interests for characterizing electrical properties of a large ensemble of nanowires. In this work, N-doped and undoped silicon nanowires (SiNWs) grown by chemical vapour deposition (CVD) on quartz substrate were characterized using optical-pump terahertz probe (OPTP) transmission experiments. Our results show that defects and ionized impurities introduced by N-doping the CVD-grown SiNWs tend to reduce the photoexcited carrier lifetime and degrade their conductivity properties. Capture mechanisms by the surface trap states play a key role on the photocarrier dynamics in theses small diameters' (~100 nm) SiNWs and the doping level is found to alter this dynamics. We propose convincing capture and recombination scenarios that explain our OPTP measurements. Fits of our photoconductivity data curves, from 0.5 to 2 THz, using a Drude-plasmon conductivity model allow determining photocarrier mobility values of 190 and 70 cm2/V .s, for the undoped and N-doped NWs samples, respectively.

  7. Charge transport in TiO.sub.2./sub. films with complex percolation pathways investigated by time-resolved terahertz spectroscopy

    Czech Academy of Sciences Publication Activity Database

    Němec, Hynek; Zajac, Vít; Rychetský, Ivan; Fattakhova-Rohlfing, D.; Mandlmeier, B.; Bein, T.; Mics, Zoltan; Kužel, Petr

    2013-01-01

    Roč. 3, č. 3 (2013), s. 302-313 ISSN 2156-342X R&D Projects: GA ČR GAP204/12/0232; GA ČR GA13-12386S Grant - others:AVČR(CZ) M100101218 Institutional support: RVO:68378271 Keywords : terahertz spectroscopy * charge transport * TiO 2 nanoparticles Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 4.342, year: 2013

  8. Time-resolved terahertz spectroscopy reveals the influence of charged sensitizing quantum dots on the electron dynamics in ZnO

    Czech Academy of Sciences Publication Activity Database

    Bamini, S.N.; Němec, Hynek; Žídek, Karel; Abdellah, M.; Al-Marri, M.J.; Chábera, P.; Ponseca, C.; Zheng, K.; Pullerits, T.

    2017-01-01

    Roč. 19, č. 8 (2017), s. 6006-6012 ISSN 1463-9076 R&D Projects: GA ČR GA17-03662S Institutional support: RVO:68378271 ; RVO:61389021 Keywords : sensitized semiconductors * ultrafast dynamics * terahertz spectroscopy Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics , supercond.) Impact factor: 4.123, year: 2016

  9. Terahertz cyclotron resonance spectroscopy of an AlGaN/GaN heterostructure using a high-field pulsed magnet and an asynchronous optical sampling technique

    Energy Technology Data Exchange (ETDEWEB)

    Spencer, B. F., E-mail: Ben.Spencer@manchester.ac.uk; Smith, W. F.; Hibberd, M. T.; Dawson, P.; Graham, D. M. [School of Physics and Astronomy and the Photon Science Institute, The University of Manchester, Manchester M13 9PL (United Kingdom); Beck, M.; Bartels, A. [Laser Quantum GmbH, Max-Stromeyer-Str. 116, 78467 Konstanz (Germany); Guiney, I.; Humphreys, C. J. [Department of Materials Science and Metallurgy, 27 Charles Babbage Road, University of Cambridge, Cambridge CB3 0FS (United Kingdom)

    2016-05-23

    The effective mass, sheet carrier concentration, and mobility of electrons within a two-dimensional electron gas in an AlGaN/GaN heterostructure were determined using a laboratory-based terahertz cyclotron resonance spectrometer. The ability to perform terahertz cyclotron resonance spectroscopy with magnetic fields of up to 31 T was enabled by combining a high-field pulsed magnet with a modified asynchronous optical sampling terahertz detection scheme. This scheme allowed around 100 transmitted terahertz waveforms to be recorded over the 14 ms magnetic field pulse duration. The sheet density and mobility were measured to be 8.0 × 10{sup 12 }cm{sup −2} and 9000 cm{sup 2} V{sup −1} s{sup −1} at 77 K. The in-plane electron effective mass at the band edge was determined to be 0.228 ± 0.002m{sub 0}.

  10. Instrumentation for Reflectance Spectroscopy and Microspectroscopy with Application to Astrobiology

    Science.gov (United States)

    Mouroulis, Pantazis; Blaney, Diana L.; Green, Robert O.

    2008-01-01

    We present instrument concepts for in-situ reflectance spectroscopy over a spatial resolution range from several meters to tens of micrometers. These have been adapted to the low mass and power requirements of rover or similar platforms. Described are a miniaturized imaging spectrometer for rover mast, a combined mast and arm point spectrometer, and an imaging microspectrometer for the rover arm.

  11. Infrared, terahertz, and microwave spectroscopy of the soft and central modes in Pb (M g1 /3N b2 /3 ) O3

    Science.gov (United States)

    Nuzhnyy, D.; Petzelt, J.; Bovtun, V.; Kempa, M.; Kamba, S.; Hlinka, J.; Hehlen, B.

    2017-11-01

    From the new infrared (IR) reflectivity and time-domain terahertz spectra combined with available high-frequency dielectric data above the megahertz range in a broad temperature range of 10 to 900 K, a full picture of the soft- and central-mode behavior in the classical relaxor ferroelectric Pb (M g1 /3N b2 /3 ) O3 (PMN) is suggested. A detailed comparison is made with the recent hyper-Raman spectroscopy data [Hehlen et al., Phys. Rev. Lett. 117, 155501 (2016), 10.1103/PhysRevLett.117.155501] and also with other available experiments based on inelastic light and neutron scattering. It is revealed that each type of experiment provides slightly different data. The closest agreement is with the hyper-Raman data: both techniques yield the same number of soft-mode components and the same high-temperature softening towards the temperature T*≈400 K . In addition to evaluation of the IR-terahertz data using fitting with the standard factorized form of the dielectric function, we performed a successful fitting of the same data using the effective medium approach (EMA), originally based on the assumption that the mesoscopic structure of PMN consists of randomly oriented uniaxially anisotropic polar nanodomains (PNDs) with somewhat harder transverse optical polar modes in the direction along the local PND dipole [Hlinka et al., Phys. Rev. Lett. 96, 027601 (2006), 10.1103/PhysRevLett.96.027601]. Evaluation using Bruggeman EMA modeling has been successfully applied in the entire investigated temperature range. These results suggest that the response perpendicular to the local dipole moment, at high temperatures induced by random fields rather than PNDs, undergoes a classical softening from high temperatures with permittivity obeying the Curie-Weiss law, ɛ⊥=C /(T -TC) , where C =1.7 ×105K and TC=380 K , whereas the response parallel to it shows no softening. Below the Burns temperature, ˜620 K , a gigahertz relaxation ascribed to flipping of the PNDs emerges from the soft

  12. Ultralow surface recombination velocity in InP nanowires probed by terahertz spectroscopy.

    Science.gov (United States)

    Joyce, Hannah J; Wong-Leung, Jennifer; Yong, Chaw-Keong; Docherty, Callum J; Paiman, Suriati; Gao, Qiang; Tan, H Hoe; Jagadish, Chennupati; Lloyd-Hughes, James; Herz, Laura M; Johnston, Michael B

    2012-10-10

    Using transient terahertz photoconductivity measurements, we have made noncontact, room temperature measurements of the ultrafast charge carrier dynamics in InP nanowires. InP nanowires exhibited a very long photoconductivity lifetime of over 1 ns, and carrier lifetimes were remarkably insensitive to surface states despite the large nanowire surface area-to-volume ratio. An exceptionally low surface recombination velocity (170 cm/s) was recorded at room temperature. These results suggest that InP nanowires are prime candidates for optoelectronic devices, particularly photovoltaic devices, without the need for surface passivation. We found that the carrier mobility is not limited by nanowire diameter but is strongly limited by the presence of planar crystallographic defects such as stacking faults in these predominantly wurtzite nanowires. These findings show the great potential of very narrow InP nanowires for electronic devices but indicate that improvements in the crystallographic uniformity of InP nanowires will be critical for future nanowire device engineering.

  13. Terahertz spectroscopy on Faraday and Kerr rotations in a quantum anomalous Hall state.

    Science.gov (United States)

    Okada, Ken N; Takahashi, Youtarou; Mogi, Masataka; Yoshimi, Ryutaro; Tsukazaki, Atsushi; Takahashi, Kei S; Ogawa, Naoki; Kawasaki, Masashi; Tokura, Yoshinori

    2016-07-20

    Electrodynamic responses from three-dimensional topological insulators are characterized by the universal magnetoelectric term constituent of the Lagrangian formalism. The quantized magnetoelectric coupling, which is generally referred to as topological magnetoelectric effect, has been predicted to induce exotic phenomena including the universal low-energy magneto-optical effects. Here we report the experimental indication of the topological magnetoelectric effect, which is exemplified by magneto-optical Faraday and Kerr rotations in the quantum anomalous Hall states of magnetic topological insulator surfaces by terahertz magneto-optics. The universal relation composed of the observed Faraday and Kerr rotation angles but not of any material parameters (for example, dielectric constant and magnetic susceptibility) well exhibits the trajectory towards the fine structure constant in the quantized limit.

  14. Optical Fiber Sensing Based on Reflection Laser Spectroscopy

    Directory of Open Access Journals (Sweden)

    Gianluca Gagliardi

    2010-03-01

    Full Text Available An overview on high-resolution and fast interrogation of optical-fiber sensors relying on laser reflection spectroscopy is given. Fiber Bragg-gratings (FBGs and FBG resonators built in fibers of different types are used for strain, temperature and acceleration measurements using heterodyne-detection and optical frequency-locking techniques. Silica fiber-ring cavities are used for chemical sensing based on evanescent-wave spectroscopy. Various arrangements for signal recovery and noise reduction, as an extension of most typical spectroscopic techniques, are illustrated and results on detection performances are presented.

  15. Terahertz Wave Approach and Application on FRP Composites

    Directory of Open Access Journals (Sweden)

    Kwang-Hee Im

    2013-01-01

    Full Text Available Terahertz (THz applications have emerged as one of the most new powerful nondestructive evaluation (NDE techniques. A new T-ray time-domain spectroscopy system was utilized for detecting and evaluating orientation influence in carbon fiber-reinforced plastics (CFRPs composite laminates. Investigation of terahertz time-domain spectroscopy (THz-TDS was made, and reflection and transmission configurations were studied as a nondestructive evaluation technique. Here, the CFRP composites derived their excellent mechanical strength, stiffness, and electrical conductivity from carbon fibers. Especially, the electrical conductivity of the CFRP composites depends on the direction of unidirectional fibers since carbon fibers are electrically conducting while the epoxy matrix is not. In order to solve various material properties, the index of refraction (n and the absorption coefficient (α are derived in reflective and transmission configurations using the terahertz time-domain spectroscopy. Also, for a 48-ply thermoplastic polyphenylene-sulfide-(PPS- based CFRP solid laminate and nonconducting materials, the terahertz scanning images were made at the angles ranged from 0° to 180° with respect to the nominal fiber axis. So, the images were mapped out based on the electrical field (E-field direction in the CFRP solid laminates. It is found that the conductivity (σ depends on the angles of the nominal axis in the unidirectional fiber.

  16. Electronic properties of GaAs, InAs and InP nanowires studied by terahertz spectroscopy

    International Nuclear Information System (INIS)

    Joyce, Hannah J; Docherty, Callum J; Lloyd-Hughes, James; Herz, Laura M; Johnston, Michael B; Gao Qiang; Tan, H Hoe; Jagadish, Chennupati

    2013-01-01

    We have performed a comparative study of ultrafast charge carrier dynamics in a range of III–V nanowires using optical pump–terahertz probe spectroscopy. This versatile technique allows measurement of important parameters for device applications, including carrier lifetimes, surface recombination velocities, carrier mobilities and donor doping levels. GaAs, InAs and InP nanowires of varying diameters were measured. For all samples, the electronic response was dominated by a pronounced surface plasmon mode. Of the three nanowire materials, InAs nanowires exhibited the highest electron mobilities of 6000 cm 2 V −1 s −1 , which highlights their potential for high mobility applications, such as field effect transistors. InP nanowires exhibited the longest carrier lifetimes and the lowest surface recombination velocity of 170 cm s −1 . This very low surface recombination velocity makes InP nanowires suitable for applications where carrier lifetime is crucial, such as in photovoltaics. In contrast, the carrier lifetimes in GaAs nanowires were extremely short, of the order of picoseconds, due to the high surface recombination velocity, which was measured as 5.4 × 10 5   cm s −1 . These findings will assist in the choice of nanowires for different applications, and identify the challenges in producing nanowires suitable for future electronic and optoelectronic devices. (paper)

  17. Determination of the optical properties of melanin-pigmented human skin equivalents using terahertz time-domain spectroscopy

    Science.gov (United States)

    Lipscomb, Dawn; Echchgadda, Ibtissam; Peralta, Xomalin G.; Wilmink, Gerald J.

    2013-02-01

    Terahertz time-domain spectroscopy (THz-TDS) methods have been utilized in previous studies in order to characterize the optical properties of skin and its primary constituents (i.e., water, collagen, and keratin). However, similar experiments have not yet been performed to investigate whether melanocytes and the melanin pigment that they synthesize contribute to skin's optical properties. In this study, we used THz-TDS methods operating in transmission geometry to measure the optical properties of in vitro human skin equivalents with or without normal human melanocytes. Skin equivalents were cultured for three weeks to promote gradual melanogenesis, and THz time domain data were collected at various time intervals. Frequency-domain analysis techniques were performed to determine the index of refraction (n) and absorption coefficient (μa) for each skin sample over the frequency range of 0.1-2.0 THz. We found that for all samples as frequency increased, n decreased exponentially and the μa increased linearly. Additionally, we observed that skin samples with higher levels of melanin exhibited greater n and μa values than the non-pigmented samples. Our results indicate that melanocytes and the degree of melanin pigmentation contribute in an appreciable manner to the skin's optical properties. Future studies will be performed to examine whether these contributions are observed in human skin in vivo.

  18. Evaluation of Penicillium digitatum sterilization using non-equilibrium atmospheric pressure plasma by terahertz time-domain spectroscopy

    Science.gov (United States)

    Hiraoka, Takehiro; Ebizuka, Noboru; Takeda, Keigo; Ohta, Takayuki; Kondo, Hiroki; Ishikawa, Kenji; Kawase, Kodo; Ito, Masafumi; Sekine, Makoto; Hori, Masaru

    2011-10-01

    Recently, the plasma sterilization has attracted much attention as a new sterilization technique that takes the place of spraying agricultural chemicals. The conventional methods for sterilization evaluation, was demanded to culture the samples for several days after plasma treatment. Then, we focused on Terahertz time-domain spectroscopy (THz-TDS). At the THz region, vibrational modes of biological molecules and fingerprint spectra of biologically-relevant molecules were also observed. In this study, our purpose was measurement of the fingerprint spectrum of the Penicillium digitatum (PD) spore and establishment of sterilization method by THz-TDS. The sample was 40mg/ml PD spore suspensions which dropped on cover glass. The atmospheric pressure plasma generated under the conditions which Ar gas flow was 3slm, and alternating voltage of 6kV was applied. The samples were exposed the plasma from 10mm distance for 10 minutes. We could obtain the fingerprint spectrum of the PD spore from 0.5 to 0.9THz. This result indicated the possibility of in-situ evaluation for PD sterilization using THz-TDS.

  19. Effect of in-material losses on terahertz absorption, transmission, and reflection in photonic crystals made of polar dielectrics

    Energy Technology Data Exchange (ETDEWEB)

    Serebryannikov, Andriy E., E-mail: andser@amu.edu.pl [Faculty of Physics, Adam Mickiewicz University, 61-614 Poznań (Poland); Nanotechnology Research Center—NANOTAM, Bilkent University, 06800 Ankara (Turkey); Nojima, S. [Yokohama City University, Department of Nanosystem Science, Graduate School of Nanobioscience, Kanazawa Ku, 22-2 Seto, Yokohama, Kanagawa 2360027 (Japan); Alici, K. B. [TUBITAK Marmara Research Center, Materials Institute, 41470 Gebze, Kocaeli (Turkey); Ozbay, Ekmel [Nanotechnology Research Center—NANOTAM, Bilkent University, 06800 Ankara (Turkey)

    2015-10-07

    The effect of the material absorption factor on terahertz absorption (A), transmittance (T), and reflectance (R) for slabs of PhC that comprise rods made of GaAs, a polar dielectric, is studied. The main goal was to illustrate how critical a choice of the absorption factor for simulations is and to indicate the importance of the possible modification of the absorption ability by using either active or lossy impurities. The spectra of A, T, and R are strongly sensitive to the location of the polaritonic gap with respect to the photonic pass and stop bands connected with periodicity that enables the efficient combination of the effects of material and structural parameters. It will be shown that the spectra can strongly depend on the utilized value of the material absorption factor. In particular, both narrow and wide absorption bands may appear owing to a variation of the material parameters with a frequency in the vicinity of the polaritonic gap. The latter are often achieved at wideband suppression of transmission, so that an ultra-wide stop band can appear as a result of adjustment of the stop bands having different origin. The results obtained at simultaneous variation of the absorption factor and frequency, and angle of incidence and frequency, indicate the possibility of the existence of wide ranges of tolerance, in which the basic features do remain. This allows for mitigating the accuracy requirements for the absorption factor in simulations and promises the efficient absorption of nonmonochromatic waves and beams with a wide angular spectrum. Suppression of narrowband effects in transmission is demonstrated at rather large values of the absorption factor, when they appear due to either the defect modes related to structural defects or dispersion inspired variations of the material parameters in the vicinity of the polaritonic gap. Comparison with auxiliary structures helps one to detect the common features and differences of homogeneous slabs and slabs of a

  20. Time-resolved terahertz spectroscopy of electrically conductive metal-organic frameworks doped with redox active species

    Science.gov (United States)

    Alberding, Brian G.; Heilweil, Edwin J.

    2015-09-01

    Metal-Organic Frameworks (MOFs) are three-dimensional coordination polymers that are well known for large pore surface area and their ability to adsorb molecules from both the gaseous and solution phases. In general, MOFs are electrically insulating, but promising opportunities for tuning the electronic structure exist because MOFs possess synthetic versatility; the metal and organic ligand subunits can be exchanged or dopant molecules can be introduced into the pore space. Two such MOFs with demonstrated electrical conductivity are Cu3(1,3,5-benzenetricarboxylate)2, a.k.a HKUST-1, and Cu[Ni(pyrazine-2,3-dithiolate)2]. Herein, these two MOFs have been infiltrated with the redox active species 7,7,8,8-tetracyanoquinodimethane (TCNQ) and iodine under solution phase conditions and shown to produce redox products within the MOF pore space. Vibrational bands assignable to TCNQ anion and triiodide anion have been observed in the Mid-IR and Terahertz ranges using FTIR Spectroscopy. The MOF samples have been further investigated by Time-Resolved Terehertz Spectroscopy (TRTS). Using this technique, the charge mobility, separation, and recombination dynamics have been followed on the picosecond time scale following photoexcitation with visible radiation. The preliminary results show that the MOF samples have small inherent photoconductivity with charge separation lifetimes on the order of a few picoseconds. In the case of HKUST-1, the MOF can also be supported by a TiO2 film and initial results show that charge injection into the TiO2 layer occurs with a comparable efficiency to the dye sensitizer N3, [cis-Bis(isothiocyanato)-bis(2,2'-bipyridyl-4,4'-dicarboxylato ruthenium(II)], and therefore this MOF has potential as a new light absorbing and charge conducting material in photovoltaic devices.

  1. Terahertz time domain spectroscopy of amorphous and crystalline aluminum oxide nanostructures synthesized by thermal decomposition of AACH

    Energy Technology Data Exchange (ETDEWEB)

    Mehboob, Shoaib, E-mail: smehboob@pieas.edu.pk [National Center for Nanotechnology, Department of Metallurgy and Materials Engineering, Pakistan Institute of Engineering and Applied Sciences (PIEAS), Nilore 45650, Islamabad (Pakistan); Mehmood, Mazhar [National Center for Nanotechnology, Department of Metallurgy and Materials Engineering, Pakistan Institute of Engineering and Applied Sciences (PIEAS), Nilore 45650, Islamabad (Pakistan); Ahmed, Mushtaq [National Institute of Lasers and Optronics (NILOP), Nilore 45650, Islamabad (Pakistan); Ahmad, Jamil; Tanvir, Muhammad Tauseef [National Center for Nanotechnology, Department of Metallurgy and Materials Engineering, Pakistan Institute of Engineering and Applied Sciences (PIEAS), Nilore 45650, Islamabad (Pakistan); Ahmad, Izhar [National Institute of Lasers and Optronics (NILOP), Nilore 45650, Islamabad (Pakistan); Hassan, Syed Mujtaba ul [National Center for Nanotechnology, Department of Metallurgy and Materials Engineering, Pakistan Institute of Engineering and Applied Sciences (PIEAS), Nilore 45650, Islamabad (Pakistan)

    2017-04-15

    The objective of this work is to study the changes in optical and dielectric properties with the transformation of aluminum ammonium carbonate hydroxide (AACH) to α-alumina, using terahertz time domain spectroscopy (THz-TDS). The nanostructured AACH was synthesized by hydrothermal treatment of the raw chemicals at 140 °C for 12 h. This AACH was then calcined at different temperatures. The AACH was decomposed to amorphous phase at 400 °C and transformed to δ* + α-alumina at 1000 °C. Finally, the crystalline α-alumina was achieved at 1200 °C. X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy were employed to identify the phases formed after calcination. The morphology of samples was studied using scanning electron microscopy (SEM), which revealed that the AACH sample had rod-like morphology which was retained in the calcined samples. THz-TDS measurements showed that AACH had lowest refractive index in the frequency range of measurements. The refractive index at 0.1 THZ increased from 2.41 for AACH to 2.58 for the amorphous phase and to 2.87 for the crystalline α-alumina. The real part of complex permittivity increased with the calcination temperature. Further, the absorption coefficient was highest for AACH, which reduced with calcination temperature. The amorphous phase had higher absorption coefficient than the crystalline alumina. - Highlights: • Aluminum oxide nanostructures were obtained by thermal decomposition of AACH. • Crystalline phases of aluminum oxide have higher refractive index than that of amorphous phase. • The removal of heavier ionic species led to the lower absorption of THz radiations.

  2. 3D measurements of live cells via digital holographic microscopy and terahertz spectroscopy

    Science.gov (United States)

    Park, Jun Yong; Oser, Dorian; Iapozzuto, Peter; Norbury, Sean; Mahajan, Supriya; Khmaladze, Alexander; Sharikova, Anna

    2016-03-01

    This is a study of the central nervous system (CNS) cells, including brain micro vascular endothelial cells (BMV) that constitute the blood brain barrier, and C6 glial cells that are the predominant cell in the brain. The cells are exposed to various chemicals by non-invasive, label-free methods. Digital holographic microscopy (DHM) is a technique that records an interference pattern between an object and reference waves, so that the computationally reconstructed holographic image contains both amplitude and phase information, and 3D images are obtained. The measurement of cell cultures by digital holographic microscopy yields information about cell death mechanisms, since these processes are correlated with individual cell volume. Our in-house DHM combines a visible (red) laser source with a conventional microscope base, and LabVIEW-run data processing. Terahertz spectral signatures are associated with structural changes in molecules and provide complementary information about cells. Both CNS cells BMV and C6 cells are treated with the drug "Methamphetamine" (METH), which induces apoptosis in neuronal cells and exhibits decrease in cell volume, a characteristic of cells undergoing apoptosis (induced cell death). METH can cause CNS cell death by cross-talk between mitochondria-, endoplasmic reticulum-, and receptor-mediated apoptotic events, all of which results in drug induced changes in neuroplasticity and significant neuropathology. Doxorubicin (DOX), a popular anticancer drug, is used as a control. We observe that METH treatment resulted in more pronounced cell volume shrinkage in both the BMV and C6 cells, as compared to DOX-induced cell apoptosis.

  3. Modelling terahertz radiation absorption and reflection with computational phantoms of skin and associated appendages

    Science.gov (United States)

    Vilagosh, Zoltan; Lajevardipour, Alireza; Wood, Andrew

    2018-01-01

    Finite-difference time-domain (FDTD) computational phantoms aid the analysis of THz radiation interaction with human skin. The presented computational phantoms have accurate anatomical layering and electromagnetic properties. A novel "large sheet" simulation technique is used allowing for a realistic representation of lateral absorption and reflection of in-vivo measurements. Simulations carried out to date have indicated that hair follicles act as THz propagation channels and confirms the possible role of melanin, both in nevi and skin pigmentation, to act as a significant absorber of THz radiation. A novel freezing technique has promise in increasing the depth of skin penetration of THz radiation to aid diagnostic imaging.

  4. Terahertz metamaterials

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Hou-tong [Los Alamos National Laboratory; Taylor, Antoineete J [Los Alamos National Laboratory; Azad, Abul K [Los Alamos National Laboratory; O' Hara, John F [Los Alamos National Laboratory

    2009-01-01

    In this paper we present our recent developments in terahertz (THz) metamaterials and devices. Planar THz metamaterials and their complementary structures fabricated on suitable substrates have shown electric resonant response, which causes the band-pass or band-stop property in THz transmission and reflection. The operational frequency can be further tuned up to 20% upon photoexcitation of an integrated semiconductor region in the splitring resonators as the metamaterial elements. On the other hand, the use of semiconductors as metamaterial substrates enables dynamical control of metamaterial resonances through photoexcitation, and reducing the substrate carrier lifetime further enables an ultrafast switching recovery. The metamaterial resonances can also be actively controlled by application of a voltage bias when they are fabricated on semiconductor substrates with appropriate doping concentration and thickness. Using this electrically driven approach, THz modulation depth up to 80% and modulation speed of 2 MHz at room temperature have been demonstrated, which suggests practical THz applications.

  5. Asymmetric planar terahertz metamaterials

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Ramjan [Los Alamos National Laboratory; Al - Naib, Ibraheem A. I. [PHILIPPS UNIV; Koch, Martin [PHILIPPS UNIV; Zhang, Weili [OKLAHOMA STATE UNIV

    2010-01-01

    Using terahertz time-domain spectroscopy, we report an experimental observation of three distinct resonances in split ring resonators (SRRs) for both vertical and horizontal electric field polarizations at normal incidence. Breaking the symmetry in SRRs by gradually displacing the capacitive gap from the centre towards the comer of the ring allows for an 85% modulation of the fundamental inductive-capacitive (LC) resonance. Increasing asymmetry leads to the evolution of an otherwise inaccessible high quality factor electric quadrupole resonance that can be exploited for bio-sensing applications in the terahertz region.

  6. Assessing human skin with diffuse reflectance spectroscopy and colorimetry

    Science.gov (United States)

    Seo, InSeok; Liu, Yang; Bargo, Paulo R.; Kollias, Nikiforos

    2012-02-01

    Colorimetry has been used as an objective measure of perceived skin color by human eye to document and score physiological responses of the skin from external insults. CIE color space values (L*, a* and b*) are the most commonly used parameters to correlate visually perceived color attributes such as L* for pigment, a* for erythema, and b* for sallowness of the skin. In this study, we investigated the relation of Lab color scale to the amount of major skin chromophores (oxy-, deoxyhemoglobin and melanin) calculated from diffuse reflectance spectroscopy. Thirty two healthy human subjects with ages from 20 to 70 years old, skin types I-VI, were recruited for the study. DRS and colorimetry measurements were taken from the left and right cheeks, and on the right upper inner arm. The melanin content calculated from 630-700 nm range of DRS measurements was shown to correlate with the lightness of skin (L*) for most skin types. For subjects with medium-to-light complexion, melanin measured at the blue part spectrum and hemoglobin interfered on the relation of lightness of the skin color to the melanin content. The sallowness of the skin that is quantified by the melanin contribution at the blue part spectrum of DRS was found to be related to b* scale. This study demonstrates the importance of documenting skin color by assessing individual skin chromophores with diffuse reflectance spectroscopy, in comparison to colorimetry assessment.

  7. Autofluorescence and diffuse reflectance patterns in cervical spectroscopy

    Science.gov (United States)

    Marin, Nena Maribel

    Fluorescence and diffuse reflectance spectroscopy are two new optical technologies, which have shown promise to aid in the real time, non-invasive identification of cancers and precancers. Spectral patterns carry a fingerprint of scattering, absorption and fluorescence properties in tissue. Scattering, absorption and fluorescence in tissue are directly affected by biological features that are diagnostically significant, such as nuclear size, micro-vessel density, volume fraction of collagen fibers, tissue oxygenation and cell metabolism. Thus, analysis of spectral patterns can unlock a wealth of information directly related with the onset and progression of disease. Data from a Phase II clinical trial to assess the technical efficacy of fluorescence and diffuse reflectance spectroscopy acquired from 850 women at three clinical locations with two research grade optical devices is calibrated and analyzed. Tools to process and standardize spectra so that data from multiple spectrometers can be combined and analyzed are presented. Methodologies for calibration and quality assurance of optical systems are established to simplify design issues and ensure validity of data for future clinical trials. Empirically based algorithms, using multivariate statistical approaches are applied to spectra and evaluated as a clinical diagnostic tool. Physically based algorithms, using mathematical models of light propagation in tissue are presented. The presented mathematical model combines a diffusion theory in P3 approximation reflectance model and a 2-layer fluorescence model using exponential attenuation and diffusion theory. The resulting adjoint fluorescence and reflectance model extracts twelve optical properties characterizing fluorescence efficiency of cervical epithelium and stroma fluorophores, stromal hemoglobin and collagen absorption, oxygen saturation, and stromal scattering strength and shape. Validations with Monte Carlo simulations show that adjoint model extracted

  8. Polarization contrast linear spectroscopies for cubic semiconductors under stress: macro- and micro-reflectance difference spectroscopies

    Energy Technology Data Exchange (ETDEWEB)

    Lastras-Martinez, L.F.; Balderas-Navarro, R.E.; Castro-Garcia, R.; Herrera-Jasso, R.; Lastras-Martinez, A. [Instituto de Investigacion en Comunicacion Optica, Universidad Autonoma de San Luis Potosi, Alvaro Obregon 64, 78000 San Luis Potosi, S.L.P. (Mexico); Chavira-Rodriguez, M. [Departamento de Fisico Matematicas, Universidad Autonoma de San Luis Potosi, Alvaro Obregon 64, 78000 San Luis Potosi, S.L.P. (Mexico)

    2011-01-15

    The technique to measure optical anisotropies (OA) in cubic semiconductors is termed either reflectance difference spectroscopy (RDS) or reflectance anisotropy spectroscopy (RAS). In this paper we report on the application of RDS/RAS to a number of cubic semiconductors. We discuss RD spectra of GaAs, Si, CdTe, GaP, InP and GaSb (001) surfaces, induced by an uniaxial stress applied along [110] crystal directions. We show that all RD spectra can be explained in terms of a phenomenological model based on a perturbative Hamiltonian. We further report on measurements of spatial-resolved RDS measurements of GaAs employing a newly developed micro-RD spectrometer with a spatial resolution of 5 {mu}m. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  9. Terahertz reflection spectroscopy of aqueous NaCl and LiCl solutions

    DEFF Research Database (Denmark)

    Jepsen, Peter Uhd; Merbold, Hannes

    2010-01-01

    frequencies. Whereas both the real and imaginary part of the permittivity of NaCl increases with concentration,we see that the imaginary part of the permittivity of LiCl (related to the absorption)decreases with increasing salt concentration. We relate these changes to the behavior...

  10. Optimization of a coherent synchrotron radiation source in the Tera-hertz range for high-resolution spectroscopy of molecules of astrophysical interest

    International Nuclear Information System (INIS)

    Barros, J.

    2012-01-01

    Fourier Transform spectroscopy is the most used multiplex tool for high-resolution measurements in the infrared range. Its extension to the Tera-hertz domain is of great interest for spectroscopic studies of interstellar molecules. This application is however hampered by the lack of dedicated, broadband sources with a sufficient intensity and stability. In this work, Coherent Synchrotron Radiation (CSR) was used as a source for molecular spectroscopy at high resolution on the AILES infrared and Tera-hertz beamline of SOLEIL synchrotron. The beamline being optimized for far-infrared, we could characterize the properties of CSR and compare them to the incoherent synchrotron radiation. A double detection system allowed to correct the effect of the source-related instabilities, hence to significantly increase the signal-to-noise ratio. Pure rotational spectra were measured using these developments. The case of the propynal molecule, for which a refined set of rotational and centrifugal distortion constants was calculated, proves the complementarity between CSR and the classical microwave or infrared sources. (author)

  11. Microfluidic Devices for Terahertz Spectroscopy of Live Cells Toward Lab-on-a-Chip Applications

    Directory of Open Access Journals (Sweden)

    Qi Tang

    2016-04-01

    Full Text Available THz spectroscopy is an emerging technique for studying the dynamics and interactions of cells and biomolecules, but many practical challenges still remain in experimental studies. We present a prototype of simple and inexpensive cell-trapping microfluidic chip for THz spectroscopic study of live cells. Cells are transported, trapped and concentrated into the THz exposure region by applying an AC bias signal while the chip maintains a steady temperature at 37 °C by resistive heating. We conduct some preliminary experiments on E. coli and T-cell solution and compare the transmission spectra of empty channels, channels filled with aqueous media only, and channels filled with aqueous media with un-concentrated and concentrated cells.

  12. Analysis of contaminants on electronic components by reflectance FTIR spectroscopy

    International Nuclear Information System (INIS)

    Griffith, G.W.

    1982-09-01

    The analysis of electronic component contaminants by infrared spectroscopy is often a difficult process. Most of the contaminants are very small, which necessitates the use of microsampling techniques. Beam condensers will provide the required sensitivity but most require that the sample be removed from the substrate before analysis. Since it can be difficult and time consuming, it is usually an undesirable approach. Micro ATR work can also be exasperating, due to the difficulty of positioning the sample at the correct place under the ATR plate in order to record a spectrum. This paper describes a modified reflection beam condensor which has been adapted to a Nicolet 7199 FTIR. The sample beam is directed onto the sample surface and reflected from the substrate back to the detector. A micropositioning XYZ stage and a close-focusing telescope are used to position the contaminant directly under the infrared beam. It is possible to analyze contaminants on 1 mm wide leads surrounded by an epoxy matrix using this device. Typical spectra of contaminants found on small circuit boards are included

  13. Ultrafast optical pump terahertz-probe spectroscopy of strongly correlated electron materials

    International Nuclear Information System (INIS)

    Averitt, R.D.; Taylor, Antoinette J.; Thorsmolle, V.K.; Jia, Quanxi; Lobad, A.I.; Trugman, S.A.

    2001-01-01

    We have used optical-pump far-infrared probe spectroscopy to probe the low energy electron dynamics of high temperature superconductors and colossal magnetoresistance manganites. For the superconductor YBa2Cu3O7, picosecond conductivity measurements probe the interplay between Cooper-pairs and quasiparticles. In optimally doped films, the recovery time for long-range phase-coherent pairing increases from ∼1.5 ps at 4K to ∼3.5 ps near Tc, consistent with the closing of the superconducting gap. For underdoped films, the measured recovery time is temperature independent (3.5 ps) in accordance with the presence of a pseudogap. Ultrafast picosecond measurements of optically induced changes in the absolute conductivity of La0:7M0:3MnO3 thin films (M = Ca, Sr) from 10K to ∼0.9Tc reveal a two-component relaxation. A fast, ∼2 ps, conductivity decrease arises from optically induced modification of the effective phonon temperature. The slower component, related to spin-lattice relaxation, has a lifetime that increases upon approaching Tc from below in accordance with an increasing spin specific heat. Our results indicate that for T<< Tc, the conductivity is determined by incoherent phonons while spin fluctuations dominate near Tc.

  14. Ultrafast carrier dynamics in Br.sup.+./sup.-bombarded InP studied by time-resolved terahertz spectroscopy

    Czech Academy of Sciences Publication Activity Database

    Němec, Hynek; Fekete, Ladislav; Kadlec, Filip; Kužel, Petr

    2008-01-01

    Roč. 78, č. 23 (2008), 235206/1-235206/7 ISSN 1098-0121 R&D Projects: GA MŠk LC512 Institutional research plan: CEZ:AV0Z10100520 Keywords : InP * carrier lifetime * carrier mobility * ultrafast * ion-bombardment * terahertz Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.322, year: 2008

  15. Hydration kinetics of cement composites with varying water-cement ratio using terahertz spectroscopy

    Science.gov (United States)

    Ray, Shaumik; Dash, Jyotirmayee; Devi, Nirmala; Sasmal, Saptarshi; Pesala, Bala

    2015-03-01

    Cement is mixed with water in an optimum ratio to form concrete with desirable mechanical strength and durability. The ability to track the consumption of major cement constituents, viz., Tri- and Dicalcium Silicates (C3S, C2S) reacting with water along with the formation of key hydration products, viz., Calcium-Silicate-Hydrate (C-S-H) which gives the overall strength to the concrete and Calcium Hydroxide (Ca(OH)2), a hydration product which reduces the strength and durability, using an efficient technique is highly desirable. Optimizing the amount of water to be mixed with cement is one of the main parameters which determine the strength of concrete. In this work, THz spectroscopy has been employed to track the variation in hydration kinetics for concrete samples with different water-cement ratios, viz., 0.3, 0.4, 0.5 and 0.6. Results show that for the sample with water-cement ratio of 0.3, significant amount of the C3S and C2S remain unreacted even after the initial hydration period of 28 days while for the cement with water-cement ratio of 0.6, most of the constituents get consumed during this stage. Analysis of the formation of Ca(OH)2 has been done which shows that the concrete sample with water-cement ratio of 0.6 produces the highest amount of Ca(OH)2 due to higher consumption of C3S/C2S in presence of excess water which is not desirable. Samples with water-cement ratio of 0.4 and 0.5 show more controlled reaction during the hydration which can imply formation of an optimized level of desired hydration products resulting in a more mechanically strong and durable concrete.

  16. Ultrabroadband terahertz conductivity of Si nanocrystal films

    DEFF Research Database (Denmark)

    Cooke, D. G.; Meldrum, A.; Jepsen, P. Uhd

    2012-01-01

    The terahertz conductivity of silicon nanoparticles embedded in glass with varying density is studied with ultra-broadband terahertz spectroscopy on picosecond time scales following fs optical excitation. The transition from relatively isolated charge carriers to densities which allow inter...... the applicability of this simple model to the conductivity of nanoparticle ensembles over the entire THz spectral window....

  17. Probing skin interaction with hydrogen peroxide using diffuse reflectance spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Zonios, George [Department of Materials Science and Engineering, University of Ioannina, 45110 Ioannina (Greece); Dimou, Aikaterini [Department of Materials Science and Engineering, University of Ioannina, 45110 Ioannina (Greece); Galaris, Dimitrios [Laboratory of Biological Chemistry, School of Medicine, University of Ioannina, 45110 Ioannina (Greece)

    2008-01-07

    Hydrogen peroxide is an important oxidizing agent in biological systems. In dermatology, it is frequently used as topical antiseptic, it has a haemostatic function, it can cause skin blanching, and it can facilitate skin tanning. In this work, we investigated skin interaction with hydrogen peroxide, non-invasively, using diffuse reflectance spectroscopy. We observed transient changes in the oxyhaemoglobin and deoxyhaemoglobin concentrations as a result of topical application of dilute H{sub 2}O{sub 2} solutions to the skin, with changes in deoxyhaemoglobin concentration being more pronounced. Furthermore, we did not observe any appreciable changes in melanin absorption properties as well as in the skin scattering properties. We also found no evidence for production of oxidized haemoglobin forms. Our observations are consistent with an at least partial decomposition of hydrogen peroxide within the stratum corneum and epidermis, with the resulting oxygen and/or remaining hydrogen peroxide inducing vasoconstriction to dermal blood vessels and increasing haemoglobin oxygen saturation. An assessment of the effects of topical application of hydrogen peroxide to the skin may serve as the basis for the development of non-invasive techniques to measure skin antioxidant capacity and also may shed light onto skin related disorders such as vitiligo.

  18. Probing skin interaction with hydrogen peroxide using diffuse reflectance spectroscopy

    International Nuclear Information System (INIS)

    Zonios, George; Dimou, Aikaterini; Galaris, Dimitrios

    2008-01-01

    Hydrogen peroxide is an important oxidizing agent in biological systems. In dermatology, it is frequently used as topical antiseptic, it has a haemostatic function, it can cause skin blanching, and it can facilitate skin tanning. In this work, we investigated skin interaction with hydrogen peroxide, non-invasively, using diffuse reflectance spectroscopy. We observed transient changes in the oxyhaemoglobin and deoxyhaemoglobin concentrations as a result of topical application of dilute H 2 O 2 solutions to the skin, with changes in deoxyhaemoglobin concentration being more pronounced. Furthermore, we did not observe any appreciable changes in melanin absorption properties as well as in the skin scattering properties. We also found no evidence for production of oxidized haemoglobin forms. Our observations are consistent with an at least partial decomposition of hydrogen peroxide within the stratum corneum and epidermis, with the resulting oxygen and/or remaining hydrogen peroxide inducing vasoconstriction to dermal blood vessels and increasing haemoglobin oxygen saturation. An assessment of the effects of topical application of hydrogen peroxide to the skin may serve as the basis for the development of non-invasive techniques to measure skin antioxidant capacity and also may shed light onto skin related disorders such as vitiligo

  19. Diffuse reflectance spectroscopy for the measurement of tissue oxygen saturation

    International Nuclear Information System (INIS)

    Sircan-Kucuksayan, A; Canpolat, M; Uyuklu, M

    2015-01-01

    Tissue oxygen saturation (StO 2 ) is a useful parameter for medical applications. A spectroscopic method has been developed to detect pathologic tissues, due to a lack of normal blood circulation, by measuring StO 2 . In this study, human blood samples with different levels of oxygen saturation have been prepared and spectra were acquired using an optical fiber probe to investigate the correlation between the oxygen saturation levels and the spectra. A linear correlation between the oxygen saturation and ratio of the intensities (760 nm to 790 nm) of the spectra acquired from blood samples has been found. In a validation study, oxygen saturations of the blood samples were estimated from the spectroscopic measurements with an error of 2.9%. It has also been shown that the linear dependence between the ratio and the oxygen saturation of the blood samples was valid for the blood samples with different hematocrits. Spectra were acquired from the forearms of 30 healthy volunteers to estimate StO 2 prior to, at the beginning of, after 2 min, and at the release of total vascular occlusion. The average StO 2 of a forearm before and after the two minutes occlusion was significantly different. The results suggested that optical reflectance spectroscopy is a sensitive method to estimate the StO 2 levels of human tissue. The technique developed to measure StO 2 has potential to detect ischemia in real time. (paper)

  20. Intramyocardial oxygen transport by quantitative diffuse reflectance spectroscopy in calves

    Science.gov (United States)

    Lindbergh, Tobias; Larsson, Marcus; Szabó, Zoltán; Casimir-Ahn, Henrik; Strömberg, Tomas

    2010-03-01

    Intramyocardial oxygen transport was assessed during open-chest surgery in calves by diffuse reflectance spectroscopy using a small intramuscular fiber-optic probe. The sum of hemo- and myoglobin tissue fraction and oxygen saturation, the tissue fraction and oxidation of cytochrome aa3, and the tissue fraction of methemoglobin were estimated using a calibrated empirical light transport model. Increasing the oxygen content in the inhaled gas, 21%-50%-100%, in five calves (group A) gave an increasing oxygen saturation of 19+/-4%, 24+/-5%, and 28+/-8% (panimals increased with LVAD pump speed (p<0.001, ANOVA) and with oxygen content in inhaled gas (p<0.001, ANOVA). The cytochrome aa3 oxidation level was above 96% in both group A and group B calves, including the two cases involving cardiac arrest. In conclusion, the estimated tissue fractions and oxygenation/oxidation levels of the myocardial chromophores during respiratory and hemodynamic provocations were in agreement with previously presented results, demonstrating the potential of the method.

  1. The effect of the flexibility of hydrogen bonding network on low-frequency motions of amino acids. Evidence from Terahertz spectroscopy and DFT calculations

    Science.gov (United States)

    Li, Yin; Lukács, András; Bordács, Sándor; Móczár, János; Nyitrai, Miklós; Hebling, János

    2018-02-01

    Low-frequency modes of L-Asp and L-Asn were studied in the range from 0.1 to 3.0 THz using time-domain Terahertz spectroscopy and density functional theory calculation. The results show that PBE-D2 shows more success than BLYP-D2 in prediction of THz absorption spectra. To compare their low-frequency modes, we adopted ;vibrational character ID strips; proposed by Schmuttenmaer and coworkers [Journal of Physical Chemistry B, 117, 10444(2013)]. We found that the most intense THz absorption peaks of two compounds both involve severe distortion of their hydrogen bonding networks. Due to less rigid hydrogen bonding network in L-Asp, the side chain (carboxyl group) of L-Asp exhibits larger motions than that (carboxamide group) of L-Asn in low-frequency modes.

  2. Research on the differences between 2-(2-Chlorophenyl)benzimidazole and 2-(4-Chlorophenyl)benzimidazole based on terahertz time domain spectroscopy

    Science.gov (United States)

    Song, Maojiang; Yang, Fei; Liu, Liping; Shen, Li; Hu, Pengfei; Zhang, Li; Su, Caixia

    2018-05-01

    Due to wide variety of biological and pharmacological activities of benzimidazole derivatives, the differences between 2-(2-Chlorophenyl)benzimidazole and 2-(4-Chlorophenyl) benzimidazole were researched by employing terahertz time-domain spectroscopy and density functional theory systematically. Although the only difference between their molecular configurations is the arrangement of chlorine atom on chlorophenyl ring, there are distinctive differences in their fingerprint spectra in the range of 0.2-2.5 THz, such as amount, amplitude, and frequency position of absorption peaks. The validity of these results was confirmed by the theoretical results simulated by using density functional theory. The possible reasons of these differences originate from the different van der Waals forces and the different dihedral angles of the molecules within crystal cell. These results indicate the importance of this spectral range as a conformational fingerprint region where even minor changes in the molecular configuration lead to major differences in its THz absorption.

  3. Diffuse Reflectance Spectroscopy for Total Carbon Analysis of Hawaiian Soils

    Science.gov (United States)

    McDowell, M. L.; Bruland, G. L.; Deenik, J. L.; Grunwald, S.; Uchida, R.

    2010-12-01

    Accurate assessment of total carbon (Ct) content is important for fertility and nutrient management of soils, as well as for carbon sequestration studies. The non-destructive analysis of soils by diffuse reflectance spectroscopy (DRS) is a potential supplement or alternative to the traditional time-consuming and costly combustion method of Ct analysis, especially in spatial or temporal studies where sample numbers are large. We investigate the use of the visible to near-infrared (VNIR) and mid-infrared (MIR) spectra of soils coupled with chemometric analysis to determine their Ct content. Our specific focus is on Hawaiian soils of agricultural importance. Though this technique has been introduced to the soil community, it has yet to be fully tested and used in practical applications for all soil types, and this is especially true for Hawaii. In short, DRS characterizes and differentiates materials based on the variation of the light reflected by a material at certain wavelengths. This spectrum is dependent on the material’s composition, structure, and physical state. Multivariate chemometric analysis unravels the information in a set of spectra that can help predict a property such as Ct. This study benefits from the remarkably diverse soils of Hawaii. Our sample set includes 216 soil samples from 145 pedons from the main Hawaiian Islands archived at the National Soil Survey Center in Lincoln, NE, along with more than 50 newly-collected samples from Kauai, Oahu, Molokai, and Maui. In total, over 90 series from 10 of the 12 soil orders are represented. The Ct values of these samples range from < 1% - 55%. We anticipate that the diverse nature of our sample set will ensure a model with applicability to a wide variety of soils, both in Hawaii and globally. We have measured the VNIR and MIR spectra of these samples and obtained their Ct values by dry combustion. Our initial analyses are conducted using only samples obtained from the Lincoln archive. In this

  4. Diffuse Reflectance Spectroscopy for Surface Measurement of Liver Pathology.

    Science.gov (United States)

    Nilsson, Jan H; Reistad, Nina; Brange, Hannes; Öberg, Carl-Fredrik; Sturesson, Christian

    2017-01-01

    Liver parenchymal injuries such as steatosis, steatohepatitis, fibrosis, and sinusoidal obstruction syndrome can lead to increased morbidity and liver failure after liver resection. Diffuse reflectance spectroscopy (DRS) is an optical measuring method that is fast, convenient, and established. DRS has previously been used on the liver with an invasive technique consisting of a needle that is inserted into the parenchyma. We developed a DRS system with a hand-held probe that is applied to the liver surface. In this study, we investigated the impact of the liver capsule on DRS measurements and whether liver surface measurements are representative of the whole liver. We also wanted to confirm that we could discriminate between tumor and liver parenchyma by DRS. The instrumentation setup consisted of a light source, a fiber-optic contact probe, and two spectrometers connected to a computer. Patients scheduled for liver resection due to hepatic malignancy were included, and DRS measurements were performed on the excised liver part with and without the liver capsule and alongside a newly cut surface. To estimate the scattering parameters and tissue chromophore volume fractions, including blood, bile, and fat, the measured diffuse reflectance spectra were applied to an analytical model. In total, 960 DRS spectra from the excised liver tissue of 18 patients were analyzed. All factors analyzed regarding tumor versus liver tissue were significantly different. When measuring through the capsule, the blood volume fraction was found to be 8.4 ± 3.5%, the lipid volume fraction was 9.9 ± 4.7%, and the bile volume fraction was 8.2 ± 4.6%. No differences could be found between surface measurements and cross-sectional measurements. In measurements with/without the liver capsule, the differences in volume fraction were 1.63% (0.75-2.77), -0.54% (-2.97 to 0.32), and -0.15% (-1.06 to 1.24) for blood, lipid, and bile, respectively. This study shows that it is possible to manage DRS

  5. [Terahertz Spectroscopic Identification with Deep Belief Network].

    Science.gov (United States)

    Ma, Shuai; Shen, Tao; Wang, Rui-qi; Lai, Hua; Yu, Zheng-tao

    2015-12-01

    Feature extraction and classification are the key issues of terahertz spectroscopy identification. Because many materials have no apparent absorption peaks in the terahertz band, it is difficult to extract theirs terahertz spectroscopy feature and identify. To this end, a novel of identify terahertz spectroscopy approach with Deep Belief Network (DBN) was studied in this paper, which combines the advantages of DBN and K-Nearest Neighbors (KNN) classifier. Firstly, cubic spline interpolation and S-G filter were used to normalize the eight kinds of substances (ATP, Acetylcholine Bromide, Bifenthrin, Buprofezin, Carbazole, Bleomycin, Buckminster and Cylotriphosphazene) terahertz transmission spectra in the range of 0.9-6 THz. Secondly, the DBN model was built by two restricted Boltzmann machine (RBM) and then trained layer by layer using unsupervised approach. Instead of using handmade features, the DBN was employed to learn suitable features automatically with raw input data. Finally, a KNN classifier was applied to identify the terahertz spectrum. Experimental results show that using the feature learned by DBN can identify the terahertz spectrum of different substances with the recognition rate of over 90%, which demonstrates that the proposed method can automatically extract the effective features of terahertz spectrum. Furthermore, this KNN classifier was compared with others (BP neural network, SOM neural network and RBF neural network). Comparisons showed that the recognition rate of KNN classifier is better than the other three classifiers. Using the approach that automatic extract terahertz spectrum features by DBN can greatly reduce the workload of feature extraction. This proposed method shows a promising future in the application of identifying the mass terahertz spectroscopy.

  6. Total Internal Reflection Fluorescence Microscopy Imaging-Guided Confocal Single-Molecule Fluorescence Spectroscopy

    OpenAIRE

    Zheng, Desheng; Kaldaras, Leonora; Lu, H. Peter

    2013-01-01

    We have developed an integrated spectroscopy system combining total internal reflection fluorescence microscopy imaging with confocal single-molecule fluorescence spectroscopy for two-dimensional interfaces. This spectroscopy approach is capable of both multiple molecules simultaneously sampling and in situ confocal fluorescence dynamics analyses of individual molecules of interest. We have demonstrated the calibration with fluorescent microspheres, and carried out single-molecule spectroscop...

  7. High speed, High resolution terahertz spectrometers

    International Nuclear Information System (INIS)

    Kim, Youngchan; Yee, Dae Su; Yi, Miwoo; Ahn, Jaewook

    2008-01-01

    A variety of sources and methods have been developed for terahertz spectroscopy during almost two decades. Terahertz time domain spectroscopy (THz TDS)has attracted particular attention as a basic measurement method in the fields of THz science and technology. Recently, asynchronous optical sampling (AOS)THz TDS has been demonstrated, featuring rapid data acquisition and a high spectral resolution. Also, terahertz frequency comb spectroscopy (TFCS)possesses attractive features for high precision terahertz spectroscopy. In this presentation, we report on these two types of terahertz spectrometer. Our high speed, high resolution terahertz spectrometer is demonstrated using two mode locked femtosecond lasers with slightly different repetition frequencies without a mechanical delay stage. The repetition frequencies of the two femtosecond lasers are stabilized by use of two phase locked loops sharing the same reference oscillator. The time resolution of our terahertz spectrometer is measured using the cross correlation method to be 270 fs. AOS THz TDS is presented in Fig. 1, which shows a time domain waveform rapidly acquired on a 10ns time window. The inset shows a zoom into the signal with 100ps time window. The spectrum obtained by the fast Fourier Transformation (FFT)of the time domain waveform has a frequency resolution of 100MHz. The dependence of the signal to noise ratio (SNR)on the measurement time is also investigated

  8. Bridging the terahertz gap

    International Nuclear Information System (INIS)

    Davies, Giles; Linfield, Edmund

    2004-01-01

    frustrating business because it involves working in a region where established solid-state technologies fail. Nevertheless, researchers are fascinated by terahertz radiation, not least because it has many potential applications for sensing, imaging and spectroscopy across the physical, medical and biological sciences, and perhaps ultimately in communications too. (U.K.)

  9. About the use of reflectance terminology in imaging spectroscopy

    NARCIS (Netherlands)

    Schaepman-Strub, G.; Schaepman, M.E.; Dangel, S.; Painter, T.; Martonchik, J.

    2005-01-01

    Analysing databases, field and airborne spectrometer data, modelling studies and publications, a lack of consistency in the use of definitions and terminology of reflectance quantities can be observed. One example is the term `BRDF¿ (bidirectional reflectance distribution function) assigned to

  10. Terahertz imaging applied to cancer diagnosis

    Science.gov (United States)

    Brun, M.-A.; Formanek, F.; Yasuda, A.; Sekine, M.; Ando, N.; Eishii, Y.

    2010-08-01

    We report on terahertz (THz) time-domain spectroscopy imaging of 10 µm thick histological sections. The sections are prepared according to standard pathological procedures and deposited on a quartz window for measurements in reflection geometry. Simultaneous acquisition of visible images enables registration of THz images and thus the use of digital pathology tools to investigate the links between the underlying cellular structure and specific THz information. An analytic model taking into account the polarization of the THz beam, its incidence angle, the beam shift between the reference and sample pulses as well as multiple reflections within the sample is employed to determine the frequency-dependent complex refractive index. Spectral images are produced through segmentation of the extracted refractive index data using clustering methods. Comparisons of visible and THz images demonstrate spectral differences not only between tumor and healthy tissues but also within tumors. Further visualization using principal component analysis suggests different mechanisms as to the origin of image contrast.

  11. Terahertz imaging applied to cancer diagnosis

    Energy Technology Data Exchange (ETDEWEB)

    Brun, M-A; Formanek, F; Yasuda, A [Life Science Laboratory, Advanced Materials Laboratories, Sony Corporation, Tokyo Medical and Dental University, 1-5-45 Yushima Bunkyo-ku, Tokyo, 113-8510 (Japan); Sekine, M; Ando, N; Eishii, Y, E-mail: florian.formanek@jp.sony.co [Department of Human Pathology, Tokyo Medical and Dental University, 1-5-45 Yushima Bunkyo-ku, Tokyo, 113-8510 (Japan)

    2010-08-21

    We report on terahertz (THz) time-domain spectroscopy imaging of 10 {mu}m thick histological sections. The sections are prepared according to standard pathological procedures and deposited on a quartz window for measurements in reflection geometry. Simultaneous acquisition of visible images enables registration of THz images and thus the use of digital pathology tools to investigate the links between the underlying cellular structure and specific THz information. An analytic model taking into account the polarization of the THz beam, its incidence angle, the beam shift between the reference and sample pulses as well as multiple reflections within the sample is employed to determine the frequency-dependent complex refractive index. Spectral images are produced through segmentation of the extracted refractive index data using clustering methods. Comparisons of visible and THz images demonstrate spectral differences not only between tumor and healthy tissues but also within tumors. Further visualization using principal component analysis suggests different mechanisms as to the origin of image contrast.

  12. Resonant Excitation of Terahertz Surface Plasmons in Subwavelength Metal Holes

    Directory of Open Access Journals (Sweden)

    Weili Zhang

    2007-01-01

    Full Text Available We present a review of experimental studies of resonant excitation of terahertz surface plasmons in two-dimensional arrays of subwavelength metal holes. Resonant transmission efficiency higher than unity was recently achieved when normalized to the area occupied by the holes. The effects of hole shape, hole dimensions, dielectric function of metals, polarization dependence, and array film thickness on resonant terahertz transmission in metal arrays were investigated by the state-of-the-art terahertz time-domain spectroscopy. In particular, extraordinary terahertz transmission was demonstrated in arrays of subwavelength holes made even from Pb, a generally poor metal, and having thickness of only one-third of skin depth. Terahertz surface plasmons have potential applications in terahertz imaging, biosensing, interconnects, and development of integrated plasmonic components for terahertz generation and detection.

  13. Electrically continuous graphene from single crystal copper verified by terahertz conductance spectroscopy and micro four-point probe

    DEFF Research Database (Denmark)

    Buron, Jonas Christian Due; Pizzocchero, Filippo; Jessen, Bjarke Sørensen

    2014-01-01

    The electrical performance of graphene synthesized by chemical vapor deposition and transferred to insulating surfaces may be compromised by extended defects, including for instance grain boundaries, cracks, wrinkles, and tears. In this study, we experimentally investigate and compare the nano......- and microscale electrical continuity of single layer graphene grown on centimeter-sized single crystal copper with that of previously studied graphene films, grown on commercially available copper foil, after transfer to SiO2 surfaces. The electrical continuity of the graphene films is analyzed using two...... for measurement of the complex conductance response in the frequency range 1-15 terahertz, covering the entire intraband conductance spectrum, and reveals that the conductance response for the graphene grown on single crystalline copper intimately follows the Drude model for a barrier-free conductor. In contrast...

  14. Terahertz spectroscopy applied to the measurement of strengths and self-broadening coefficients for high- J lines of OCS

    Science.gov (United States)

    Matton, S.; Rohart, F.; Bocquet, R.; Mouret, G.; Bigourd, D.; Cuisset, A.; Hindle, F.

    2006-10-01

    A spectrometer operating in the 100-2000 GHz range and allowing for absolute line strength measurements has been developed. The continuous wave terahertz radiation is generated by mixing two Ti:Sapphire laser beams in a vertically integrated low temperature grown GaAs (LTG-GaAs) photomixer. Pure rotational lines of 16O 12C 32S in the ground vibrational state have been considered for J values up to 90. Observed self-broadening parameters are in agreement with those deduced from infrared experiments. For the first time in the submillimeter range, absolute line strengths have been determined, allowing for a determination of the electric dipole moment in good agreement with the value previously obtained from Stark effect measurements.

  15. Noninvasive particle sizing using camera-based diffuse reflectance spectroscopy

    DEFF Research Database (Denmark)

    Abildgaard, Otto Højager Attermann; Frisvad, Jeppe Revall; Falster, Viggo

    2016-01-01

    Diffuse reflectance measurements are useful for noninvasive inspection of optical properties such as reduced scattering and absorption coefficients. Spectroscopic analysis of these optical properties can be used for particle sizing. Systems based on optical fiber probes are commonly employed...

  16. Reflectance spectroscopy of biochemical components as indicators of tea, Camellia Sinensis, quality

    NARCIS (Netherlands)

    Bian, B.M.; Skidmore, A.K.; Schlerf, M.; Fei, T.; Liu, Y.F.; Wang, T.

    2010-01-01

    The potential of reflectance spectroscopy to estimate the concentration of biochemical compounds related to tea (Camellia sinensis (L.)) quality (total tea polyphenols and free amino acids) is demonstrated. Partial least squares regression (PLSR) was performed to establish the relationship between

  17. Diffuse reflectance spectroscopy: a new guidance tool for improvement of biopsy procedures in lung malignancies

    NARCIS (Netherlands)

    Evers, Daniel; Evers, D.J.; Nachabe, R.; Klomp, H.M.; van Sandick, J.W.; Wouters, M.W.; Lucassen, G.W.; Lucassen, Gerald; Hendriks, B.H.; Wesseling, J.; Ruers, Theo J.M.

    2012-01-01

    Background: A significant number of percutaneous intrathoracic biopsy procedures result in indeterminate cytologic or histologic diagnosis in clinical practice. Diffuse reflectance spectroscopy (DRS) is an optical technique that can distinguish different tissue types on a microscopic level. DRS may

  18. Reflectance spectroscopy of pigmented cutaneous benign and malignant lesions

    Science.gov (United States)

    Borisova, E.; Jeliazkova, Al.; Pavlova, E.; Troyanova, P.; Kundurdjiev, T.; Pavlova, P.; Avramov, L.

    2014-10-01

    For the DRS measurements of skin benign, dysplastic and malignant lesions in vivo we applied halogen lamp (LS-1, OceanOptics Inc, Dunedin, Fl, USA) as a continuous light source in the region of 400-900 nm, optical probe (6+1 fibers) for the delivery of illumination and diffuse reflected light from the skin investigated and microspectrometer USB4000 (OceanOptics Inc., Dunedin, Fl, USA) for a storage and display of the spectra detected. As a diffuse reflectance standard Spectralon® plate was used to calibrate the spectrometer. The reflectance spectra obtained from normal skin in identical anatomic sites of different patients have similar spectral shape features, slightly differ by the reflectance intensity at different wavelengths, depending on the particular patient' skin phototype. One could find diagnostically important spectral features, related to specific intensity changes for a given wavelength due to specific pigments appearance, slope changes by value and sign for the reflectance spectra curves in a specific spectral range, disappearance or manifestation of minima, related to hemoglobin absorption at 410-420 nm, 543, 575 nm. Based on the observed peculiarities multispectral analysis of the reflectance spectra of the different lesions was used and diagnostically specific features are found. Discrimination using the DRS data obtained between benign compound and dermal nevi (45 cases), dysplastic nevi (17 cases) and pigmented malignant melanoma (41 cases) lesions is achieved with a diagnostic accuracy of 96 % for the benign nevi vs. MM, and 90 % for the dysplastic nevi vs. MM.

  19. Far infrared (terahertz) spectroscopy of a series of polycyclic aromatic hydrocarbons and application to structure interpretation of asphaltenes and related compounds.

    Science.gov (United States)

    Cataldo, Franco; Angelini, Giancarlo; García-Hernández, D Aníbal; Manchado, Arturo

    2013-07-01

    A series of 33 different polycyclic aromatic hydrocarbons (PAHs) were studied by far infrared spectroscopy (terahertz spectroscopy) in the spectral range comprised between 600 and 50 cm(-1). In addition to common PAHs like naphthalene, anthracene, phenanthrene, fluoranthene, picene, pyrene, benzo[α]pyrene, and perylene, also quite unusual PAHs were studied like tetracene, pentacene, acenaphtene, acenaphtylene, triphenylene, and decacyclene. A series of alkylated naphthalenes and anthracenes were studied as well as methypyrene. Partially or totally hydrogenated PAHs were also object of the present investigation, ranging from tetrahydronaphthalene (tetralin) to decahydronaphthalene (decalin), 9,10-dihydroanthracene, 9,10-dihydrophenanthrene, hexahydropyrene, and dodecahydrotriphenylene. Finally, the large and quite rare PAHs coronene, quaterrylene, hexabenzocoronene, and dicoronylene were studied by far infrared spectroscopy. The resulting reference spectra were used in the interpretation of the chemical structure of asphaltenes (as extracted from a heavy petroleum fraction and from bitumen), the chemical structures of other petroleum fractions known as DAE (distillate aromatic extract) and RAE (residual aromatic extract), and a possible interpretation of components of the chemical structure of anthracite coal. Asphaltenes, heavy petroleum fractions, and coal were proposed as model compounds for the interpretation of the emission spectra of certain proto-planetary nebulae (PPNe) with a good matching in the mid infrared between the band pattern of the PPNe emission spectra and the spectra of these oil fractions or coal. Although this study was finalized in an astrochemical context, it may find application also in the petroleum and coal chemistry. Copyright © 2013 Elsevier B.V. All rights reserved.

  20. Terahertz Technology: A Boon to Tablet Analysis

    Science.gov (United States)

    Wagh, M. P.; Sonawane, Y. H.; Joshi, O. U.

    2009-01-01

    The terahertz gap has a frequency ranges from ∼0.3 THz to ∼10 THz in the electromagnetic spectrum which is in between microwave and infrared. The terahertz radiations are invisible to naked eye. In comparison with x-ray they are intrinsically safe, non-destructive and non-invasive. Terahertz spectroscopy enables 3D imaging of structures and materials, and the measurement of the unique spectral fingerprints of chemical and physical forms. Terahertz radiations are produced by a dendrimer based high power terahertz source and spectroscopy technologies. It resolves many of the questions left unanswered by complementary techniques, such as optical imaging, Raman and infrared spectra. In the pharmaceutical industries it enables nondestructive, internal, chemical analysis of tablets, capsules, and other dosage forms. Tablet coatings are a major factor in drug bioavailability. Therefore tablet coatings integrity and uniformity are of crucial importance to quality. Terahertz imaging gives an unparalleled certainty about the integrity of tablet coatings and the matrix performance of tablet cores. This article demonstrates the potential of terahertz pulse imaging for the analysis of tablet coating thickness by illustrating the technique on tablets. PMID:20490288

  1. [Comparative study of reflectance spectroscopy of women's acupoints around menstruation].

    Science.gov (United States)

    Jiang, Xing-Hui; Liu, Han-Ping; Guo, Zhou-Yi; Meng, Yao-Yong; Zeng, Chang-Chun; Liu, Song-Hao

    2010-12-01

    Acupoint was reaction of viscera and its optical parameter was an important characteristic of tissue. In the present work, in order to discuss specificity of acupuncture on the response of qi and blood in human body, we compared the diffuse reflectance of Taichong (LV3), Taibai (SP3), and Chongyang (ST42) before, during and after menstruation. All the acupoints had the same shape of the spectrum and troughs were all at 423.16, 544.06 and 577.47 nm. The values of reflectance during menstruation were greater than before and after menstruation, especially for SP3 and ST42 (P menstruation. Diffuse reflectance may be possibly used in the quantitative analysis of qi and blood.

  2. Light Reflectance Spectroscopy to Detect Positive Surgical Margins on Prostate Cancer Specimens.

    Science.gov (United States)

    Morgan, Monica S C; Lay, Aaron H; Wang, Xinlong; Kapur, Payal; Ozayar, Asim; Sayah, Maryam; Zeng, Li; Liu, Hanli; Roehrborn, Claus G; Cadeddu, Jeffrey A

    2016-02-01

    Intraoperative frozen section analysis is not routinely performed to determine positive surgical margins at radical prostatectomy due to time requirements and unproven clinical usefulness. Light reflectance spectroscopy, which measures light intensity reflected or backscattered from tissues, can be applied to differentiate malignant from benign tissue. We used a novel light reflectance spectroscopy probe to evaluate positive surgical margins on ex vivo radical prostatectomy specimens and correlate its findings with pathological examination. Patients with intermediate to high risk disease undergoing radical prostatectomy were enrolled. Light reflectance spectroscopy was performed on suspected malignant and benign prostate capsule immediately following organ extraction. Each light reflectance spectroscopy at 530 to 830 nm was analyzed and correlated with pathological results. A regression model and forward sequential selection algorithm were developed for optimal feature selection. Eighty percent of light reflectance spectroscopy data were selected to train a logistic regression model, which was evaluated by the remaining 20% data. This was repeated 5 times to calculate averaged sensitivity, specificity and accuracy. Light reflectance spectroscopy analysis was performed on 17 ex vivo prostate specimens, on which a total of 11 histologically positive and 22 negative surgical margins were measured. Two select features from 700 to 830 nm were identified as unique to malignant tissue. Cross-validation when performing the predictive model showed that the optical probe predicted positive surgical margins with 85% sensitivity, 86% specificity, 86% accuracy and an AUC of 0.95. Light reflectance spectroscopy can identify positive surgical margins accurately in fresh ex vivo radical prostatectomy specimens. Further study is required to determine whether such analysis may be used in real time to improve surgical decision making and decrease positive surgical margin rates

  3. Active terahertz metamaterials

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Hou-tong [Los Alamos National Laboratory; O' Hara, John F [Los Alamos National Laboratory; Taylor, Antoinette J [Los Alamos National Laboratory

    2009-01-01

    In this paper we present an overview of research in our group in terahertz (THz) metamaterials and their applications. We have developed a series of planar metamaterials operating at THz frequencies, all of which exhibit a strong resonant response. By incorporating natural materials, e.g. semiconductors, as the substrates or as critical regions of metamaterial elements, we are able to effectively control the metamaterial resonance by the application of external stimuli, e.g., photoexcitation and electrical bias. Such actively controllable metamaterials provide novel functionalities for solid-state device applications with unprecedented performance, such as THz spectroscopy, imaging, and many others.

  4. Terahertz composite imaging method

    Institute of Scientific and Technical Information of China (English)

    QIAO Xiaoli; REN Jiaojiao; ZHANG Dandan; CAO Guohua; LI Lijuan; ZHANG Xinming

    2017-01-01

    In order to improve the imaging quality of terahertz(THz) spectroscopy, Terahertz Composite Imaging Method(TCIM) is proposed. The traditional methods of improving THz spectroscopy image quality are mainly from the aspects of de-noising and image enhancement. TCIM breaks through this limitation. A set of images, reconstructed in a single data collection, can be utilized to construct two kinds of composite images. One algorithm, called Function Superposition Imaging Algorithm(FSIA), is to construct a new gray image utilizing multiple gray images through a certain function. The features of the Region Of Interest (ROI) are more obvious after operating, and it has capability of merging ROIs in multiple images. The other, called Multi-characteristics Pseudo-color Imaging Algorithm(McPcIA), is to construct a pseudo-color image by combining multiple reconstructed gray images in a single data collection. The features of ROI are enhanced by color differences. Two algorithms can not only improve the contrast of ROIs, but also increase the amount of information resulting in analysis convenience. The experimental results show that TCIM is a simple and effective tool for THz spectroscopy image analysis.

  5. Synthesis, structure, terahertz spectroscopy and luminescent properties of copper (I) complexes with bis(diphenylphosphino)methane and N-donor ligands

    Science.gov (United States)

    Fan, Wei-Wei; Li, Zhong-Feng; Li, Jiao-Bao; Yang, Yu-Ping; Yuan, Yuan; Tang, Han-Qin; Gao, Ling-Xiao; Jin, Qiong-Hua; Zhang, Zhen-Wei; Zhang, Cun-Lin

    2015-11-01

    The reactions of copper(I) salts CuX [X = Cl, OTf (OTf = CF3SO3) and ClO4] and bis(diphenylphosphino)methane (dppm) with 4,4-bipyridine (4,4-bipy), 2,2-bipyridine (2,2-bipy), isoquinoline (i-C9H7N) and 1,10-phenanthroline (phen) lead to five new copper(I) complexes: [CuCl(dppm)(i-C9H7N)]2 (1), {[CuCl(dppm)(phen)]2•5H2O}n (2), [Cu2Cl2(dppm)2(4,4-bipy)]•4CH3CN (3), [Cu(dppm)(2,2-bipy)]2(OTf)2 (4), {[Cu2Cl(dppm)2(4,4-bipy)](ClO4)}n (5). Complexes 1, 3 and 4 are of dinuclear structure with eight-membered Cu2P4C2 rings. The structure of compound 2 can be simplified as three-dimensional topology. Complex 5 is of infinite chain structure linked by 4,4-bipy. All these complexes are characterized by IR, elemental analyses, single-crystal X-ray diffraction analysis, luminescence, NMR and terahertz time-domain spectroscopy.

  6. Detection of Terahertz Radiation

    DEFF Research Database (Denmark)

    2015-01-01

    The present invention relates to a system for detecting terahertz radiation, a camera device, and a method for detecting terahertz radiation.......The present invention relates to a system for detecting terahertz radiation, a camera device, and a method for detecting terahertz radiation....

  7. Ultraviolet reflectance spectroscopy measurements of planetary materials and their analogs

    Science.gov (United States)

    Hibbitts, C.; Stockstill-Cahill, K.

    2017-12-01

    The compositions of airless solar system objects tell us about the origin and evolutionary processes that are responsible for the current state of our solar system and that shape our environment. Spacecraft have obtained UV reflectance measurements of the surfaces of Mercury, the Moon, asteroids, comets, icy satellites, and Pluto from which composition is being inferred. Most minerals absorb in the UV making studying surface composition both informative but also challenging [e.g. 1]. The UV region is sensitive to atomic and molecular electronic absorptions such as the ligand-metal charge transfer band that is present in oxides and silicates and the conduction band at vacuum UV wavelengths. Unfortunately, limited laboratory reflectance measurements in the ultraviolet hampers the interpretation of some of these planetary UV reflectance datasets. However, several laboratory efforts have been developed [e.g. 2,3] to fill the need for laboratory UV measurements. These are difficult measurements to make, being complicated by the absorptive nature of the atmosphere, requiring measurements to be conducted under vacuum or over very short path lengths of a N2-purged system. Also, the lack of a widely accepted UV diffuse reflectance standard is problematic. At the JHU-APL, bidirectional UV reflectance measurements are obtained under vacuum from 140 nm to 570 nm. Sample temperature can be controlled from 100K to 600K, which enables the study of the interaction of water ice and other volatiles with the refractory samples. Results from our laboratory research include the development of a correlation between the spectral nature of the OMCT band and the abundance of iron in low water content lunar analog glasses [3]. Also, the spectral signature of water in the UV has been investigated. While water-ice has a known strong absorption feature near 180 nm [e.g. 4], adsorbed molecular and disassociatively adsorbed OH apparently are not optically active in this spectral region [5]. We

  8. TeraHertz imaging of hidden paint layers on canvas

    NARCIS (Netherlands)

    Adam, A.J.L.; Planken, P.C.M.; Meloni, S.; Dik, J.

    2009-01-01

    We show terahertz reflection images of hidden paint layers in a painting on canvas and compare the results with X-ray Radiography and Infrared Reflectography. Our terahertz measurements show strong reflections from both the canvas/paint interface and from the raw umber/lead white interface,

  9. Scanning Terahertz Heterodyne Imaging Systems

    Science.gov (United States)

    Siegel, Peter; Dengler, Robert

    2007-01-01

    Scanning terahertz heterodyne imaging systems are now at an early stage of development. In a basic scanning terahertz heterodyne imaging system, (see Figure 1) two far-infrared lasers generate beams denoted the local-oscillator (LO) and signal that differ in frequency by an amount, denoted the intermediate frequency (IF), chosen to suit the application. The LO beam is sent directly to a mixer as one of two inputs. The signal beam is focused to a spot on or in the specimen. After transmission through or reflection from the specimen, the beams are focused to a spot on a terahertz mixer, which extracts the IF outputs. The specimen is mounted on a translation stage, by means of which the focal spot is scanned across the specimen to build up an image.

  10. Terahertz radar cross section measurements.

    Science.gov (United States)

    Iwaszczuk, Krzysztof; Heiselberg, Henning; Jepsen, Peter Uhd

    2010-12-06

    We perform angle- and frequency-resolved radar cross section (RCS) measurements on objects at terahertz frequencies. Our RCS measurements are performed on a scale model aircraft of size 5-10 cm in polar and azimuthal configurations, and correspond closely to RCS measurements with conventional radar on full-size objects. The measurements are performed in a terahertz time-domain system with freely propagating terahertz pulses generated by tilted pulse front excitation of lithium niobate crystals and measured with sub-picosecond time resolution. The application of a time domain system provides ranging information and also allows for identification of scattering points such as weaponry attached to the aircraft. The shapes of the models and positions of reflecting parts are retrieved by the filtered back projection algorithm.

  11. Terahertz ptychography.

    Science.gov (United States)

    Valzania, Lorenzo; Feurer, Thomas; Zolliker, Peter; Hack, Erwin

    2018-02-01

    We realized a phase retrieval technique using terahertz (THz) radiation as an alternative to THz digital holography, named THz ptychography. Ptychography has been used in x-ray imaging as a groundbreaking improvement of conventional coherent diffraction imaging. Here we show that ptychography can be performed at THz frequencies too. We reconstructed an amplitude and a phase object with both simulated and real data. Lateral resolution accounts to <2λ, while depth variations as low as λ/30 can be assessed.

  12. Catheter based mid-infrared reflectance and reflectance generated absorption spectroscopy

    Science.gov (United States)

    Holman, Hoi-Ying N

    2013-10-29

    A method of characterizing conditions in a tissue, by (a) providing a catheter that has a light source that emits light in selected wavenumbers within the range of mid-IR spectrum; (b) directing the light from the catheter to an area of tissue at a location inside a blood vessel of a subject; (c) collecting light reflected from the location and generating a reflectance spectra; and (d) comparing the reflectance spectra to a reference spectra of normal tissue, whereby a location having an increased number of absorbance peaks at said selected wavenumbers indicates a tissue inside the blood vessel containing a physiological marker for atherosclerosis.

  13. Cryogenic Reflectance Spectroscopy in Support of Planetary Missions

    Science.gov (United States)

    Dalton, J. B.

    2002-01-01

    Present understanding of planetary composition is based primarily on remotely-sensed data, and in particular upon ultraviolet, visible, and infrared spectroscopy. Spectra acquired by telescopic and spacecraft instruments are compared to laboratory measurements of pure materials in order to identify surface components based on characteristic absorption features. Cryogenic spectral measurements are necessary for the study of worlds beyond the Earth's orbit. While some materials exhibit only small spectral changes as a function of temperature, many others are strongly temperature-dependent. For example, hydrated salts exhibit different spectral behavior under conditions appropriate to Europa than at terrestrial temperatures. The icy satellites of the outer solar system contain significant quantities of volatile ices which do not even exist at standard temperature and pressure (STP). A comprehensive spectral database of ices and minerals covering a wide temperature range will have applications ranging from the study of comets and Kuiper Belt objects to outer planet satellites and the polar regions of Mars. Efforts are presently underway at NASA-Ames to develop capabilities which will contribute to such a database. As spacecraft instruments feature increasing spatial and spectral resolution, appropriate laboratory reference spectra become increasingly critical to accurate interpretation of the spacecraft data.

  14. Terahertz wave manipulation based on multi-bit coding artificial electromagnetic surfaces

    Science.gov (United States)

    Li, Jiu-Sheng; Zhao, Ze-Jiang; Yao, Jian-Quan

    2018-05-01

    A polarization insensitive multi-bit coding artificial electromagnetic surface is proposed for terahertz wave manipulation. The coding artificial electromagnetic surfaces composed of four-arrow-shaped particles with certain coding sequences can generate multi-bit coding in the terahertz frequencies and manipulate the reflected terahertz waves to the numerous directions by using of different coding distributions. Furthermore, we demonstrate that our coding artificial electromagnetic surfaces have strong abilities to reduce the radar cross section with polarization insensitive for TE and TM incident terahertz waves as well as linear-polarized and circular-polarized terahertz waves. This work offers an effectively strategy to realize more powerful manipulation of terahertz wave.

  15. Sub-terahertz spectroscopy reveals that proteins influence the properties of water at greater distances than previously detected

    Energy Technology Data Exchange (ETDEWEB)

    Sushko, Oleksandr; Dubrovka, Rostyslav; Donnan, Robert S., E-mail: r.donnan@qmul.ac.uk [School of Electronic Engineering and Computer Science, Queen Mary University of London, Mile End Road, London E1 4NS (United Kingdom)

    2015-02-07

    The initial purpose of the study is to systematically investigate the solvation properties of different proteins in water solution by terahertz (THz) radiation absorption. Transmission measurements of protein water solutions have been performed using a vector network analyser-driven quasi-optical bench covering the WR-3 waveguide band (0.220–0.325 THz). The following proteins, ranging from low to high molecular weight, were chosen for this study: lysozyme, myoglobin, and bovine serum albumin (BSA). Absorption properties of solutions were studied at different concentrations of proteins ranging from 2 to 100 mg/ml. The concentration-dependent absorption of protein molecules was determined by treating the solution as a two-component model first; then, based on protein absorptivity, the extent of the hydration shell is estimated. Protein molecules are shown to possess a concentration-dependent absorptivity in water solutions. Absorption curves of all three proteins sharply peak towards a dilution-limit that is attributed to the enhanced flexibility of protein and amino acid side chains. An alternative approach to the determination of hydration shell thickness is thereby suggested, based on protein absorptivity. The proposed approach is independent of the absorption of the hydration shell. The derived estimate of hydration shell thickness for each protein supports previous findings that protein-water interaction dynamics extends beyond 2-3 water solvation-layers as predicted by molecular dynamics simulations and other techniques such as NMR, X-ray scattering, and neutron scattering. According to our estimations, the radius of the dynamic hydration shell is 16, 19, and 25 Å, respectively, for lysozyme, myoglobin, and BSA proteins and correlates with the dipole moment of the protein. It is also seen that THz radiation can serve as an initial estimate of the protein hydrophobicity.

  16. Sub-terahertz spectroscopy reveals that proteins influence the properties of water at greater distances than previously detected

    International Nuclear Information System (INIS)

    Sushko, Oleksandr; Dubrovka, Rostyslav; Donnan, Robert S.

    2015-01-01

    The initial purpose of the study is to systematically investigate the solvation properties of different proteins in water solution by terahertz (THz) radiation absorption. Transmission measurements of protein water solutions have been performed using a vector network analyser-driven quasi-optical bench covering the WR-3 waveguide band (0.220–0.325 THz). The following proteins, ranging from low to high molecular weight, were chosen for this study: lysozyme, myoglobin, and bovine serum albumin (BSA). Absorption properties of solutions were studied at different concentrations of proteins ranging from 2 to 100 mg/ml. The concentration-dependent absorption of protein molecules was determined by treating the solution as a two-component model first; then, based on protein absorptivity, the extent of the hydration shell is estimated. Protein molecules are shown to possess a concentration-dependent absorptivity in water solutions. Absorption curves of all three proteins sharply peak towards a dilution-limit that is attributed to the enhanced flexibility of protein and amino acid side chains. An alternative approach to the determination of hydration shell thickness is thereby suggested, based on protein absorptivity. The proposed approach is independent of the absorption of the hydration shell. The derived estimate of hydration shell thickness for each protein supports previous findings that protein-water interaction dynamics extends beyond 2-3 water solvation-layers as predicted by molecular dynamics simulations and other techniques such as NMR, X-ray scattering, and neutron scattering. According to our estimations, the radius of the dynamic hydration shell is 16, 19, and 25 Å, respectively, for lysozyme, myoglobin, and BSA proteins and correlates with the dipole moment of the protein. It is also seen that THz radiation can serve as an initial estimate of the protein hydrophobicity

  17. [The Detection of Ultra-Broadband Terahertz Spectroscopy of InP Wafer by Using Coherent Heterodyne Time-Domain Spectrometer].

    Science.gov (United States)

    Zhang, Liang-liang; Zhang, Rui; Xu, Xiao-yan; Zhang, Cun-lin

    2016-02-01

    Indium Phosphide (InP) has attracted great physical interest because of its unique characteristics and is indispensable to both optical and electronic devices. However, the optical property of InP in the terahertz range (0. 110 THz) has not yet been fully characterized and systematically studied. The former researches about the properties of InP concentrated on the terahertz frequency between 0.1 and 4 THz. The terahertz optical properties of the InP in the range of 4-10 THz are still missing. It is fairly necessary to fully understand its properties in the entire terahertz range, which results in a better utilization as efficient terahertz devices. In this paper, we study the optical properties of undoped (100) InP wafer in the ultra-broad terahertz frequency range (0.5-18 THz) by using air-biased-coherent-detection (ABCD) system, enabling the coherent detection of terahertz wave in gases, which leads to a significant improvement on the dynamic range and sensitivity of the system. The advantage of this method is broad frequency bandwidth from 0.2 up to 18 THz which is only mainly limited by laser pulse duration since it uses ionized air as terahertz emitter and detector instead of using an electric optical crystal or photoconductive antenna. The terahertz pulse passing through the InP wafer is delayed regarding to the reference pulse and has much lower amplitude. In addition, the frequency spectrum amplitude of the terahertz sample signal drops to the noise floor level from 6.7 to 12.1 THz. At the same time InP wafer is opaque at the frequencies spanning from 6.7 to 12.1 THz. In the frequency regions of 0.8-6.7 and 12.1-18 THz it has relativemy low absorption coefficient. Meanwhile, the refractive index increases monotonously in the 0.8-6.7 THz region and 12.1-18 THz region. These findings will contribute to the design of InP based on nonlinear terahertz devices.

  18. A study of muscular tissue of animal origin by reflection-spectroscopy methods

    Science.gov (United States)

    Plotnikova, L. V.; Nechiporenko, A. P.; Orekhova, S. M.; Plotnikov, P. P.; Ishevskii, A. L.

    2017-06-01

    A comparative analysis of the spectral characteristics of the surface of muscular tissue of animal origin (pork) and its main components has been performed by the methods of diffuse reflection electronic spectroscopy (DRES) and frustrated total internal reflection IR spectroscopy. The experiments have shown that the application of the DRES method makes it possible to detect more pronounced changes in the surface optical characteristics of muscular tissue and obtain electronic spectra containing information about the component composition of its main parts under successive extraction of sarcoplasmic materials, myofibrillar proteins of the actomyosin complex, and stroma mucopolysaccharides.

  19. In situ anodization of aluminum surfaces studied by x-ray reflectivity and electrochemical impedance spectroscopy

    International Nuclear Information System (INIS)

    Bertram, F.; Evertsson, J.; Messing, M. E.; Mikkelsen, A.; Lundgren, E.; Zhang, F.; Pan, J.; Carlà, F.; Nilsson, J.-O.

    2014-01-01

    We present results from the anodization of an aluminum single crystal [Al(111)] and an aluminum alloy [Al 6060] studied by in situ x-ray reflectivity, in situ electrochemical impedance spectroscopy and ex situ scanning electron microscopy. For both samples, a linear increase of oxide film thickness with increasing anodization voltage was found. However, the slope is much higher in the single crystal case, and the break-up of the oxide film grown on the alloy occurs at a lower anodization potential than on the single crystal. The reasons for these observations are discussed as are the measured differences observed for x-ray reflectivity and electrochemical impedance spectroscopy.

  20. Excitonic terahertz photoconductivity in intrinsic semiconductor nanowires

    Science.gov (United States)

    Yan, Jie-Yun

    2018-06-01

    Excitonic terahertz photoconductivity in intrinsic semiconductor nanowires is studied. Based on the excitonic theory, the numerical method to calculate the photoconductivity spectrum in the nanowires is developed, which can simulate optical pump terahertz-probe spectroscopy measurements on real nanowires and thereby calculate the typical photoconductivity spectrum. With the help of the energetic structure deduced from the calculated linear absorption spectrum, the numerically observed shift of the resonant peak in the photoconductivity spectrum is found to result from the dominant exciton transition between excited or continuum states to the ground state, and the quantitative analysis is in good agreement with the quantum plasmon model. Besides, the dependence of the photoconductivity on the polarization of the terahertz field is also discussed. The numerical method and supporting theoretical analysis provide a new tool for experimentalists to understand the terahertz photoconductivity in intrinsic semiconductor nanowires at low temperatures or for nanowires subjected to below bandgap photoexcitation, where excitonic effects dominate.

  1. Conductivity peak, relaxation dynamics, and superconducting gap of YBa2Cu3O7 studied by terahertz and femtosecond optical spectroscopies

    International Nuclear Information System (INIS)

    Frenkel, A.; Gao, F.; Liu, Y.; Whitaker, J.F.; Uher, C.; Hou, S.Y.; Phillips, J.M.

    1996-01-01

    Recent measurements at microwave, terahertz (THz), and infrared frequencies have revealed a peak in σ 1 below T c . Based on our THz measurements, which were performed on high quality, single crystal films of YBCO (900 and 500 A), we have found that σ 1 features a peak which increases in amplitude and shifts to lower temperatures as frequency changes from 1.2 to 0.4 THz. Although the quasiparticle relaxation time extracted from these results using the two-fluid Drude model exhibits an enhancement below T c , the analysis may not be adequate to account for the strong frequency dependence of the conductivity peak by the competition between the drop in scattering rate and the decreasing normal fluid density with temperature. On the contrary, we were able to account for the frequency dependent σ 1 by fitting with Mattis-Bardeen theory (modified to include scattering) using a slower average rate of increase of the anisotropic gap than for the BCS case as temperature decreases below T c . This is consistent with the higher normal fluid density (higher than Gorter-Casimir values) from the two-fluid model interpretation of our THz results. Thus, we have found evidence of BCS coherence factors in a high-T c superconductor with a slower than BCS gap increase below T c . We have discussed the role of coherence factors to account for the presence of the conductivity peak and the absence of the peak in NMR relaxation rate. Furthermore, we have presented a model for the quasiparticle relaxation time measured by the femtosecond pump-probe spectroscopy. This model allowed us to find a fit to the temperature-dependent energy gap function which is also consistent with the slower gap increase below T c

  2. Method for rapid multidiameter single-fiber reflectance and fluorescence spectroscopy through a fiber bundle

    NARCIS (Netherlands)

    Amelink, A.; Hoy, C.L.; Gamm, U.A.; Sterenborg, H.J.C.M.; Robinson, D.J.

    2014-01-01

    We have recently demonstrated a means for quantifying the absorption and scattering properties of biological tissue through multidiameter single-fiber reflectance (MDSFR) spectroscopy. These measurements can be used to correct single-fiber fluorescence (SFF) spectra for the influence of optical

  3. Diffuse reflectance spectroscopy : toward real-time quantification of steatosis in liver

    NARCIS (Netherlands)

    Evers, Daniel J.; Westerkamp, Andrie C.; Spliethoff, Jarich W.; Pully, Vishnu V.; Hompes, Daphne; Hendriks, Benno H. W.; Prevoo, Warner; van Velthuysen, Marie-Louise F.; Porte, Robert J.; Ruers, Theo J. M.

    Assessment of fatty liver grafts during orthotopic liver transplantation is a challenge due to the lack of real-time analysis options during surgery. Diffuse reflectance spectroscopy (DRS) could be a new diagnostic tool to quickly assess steatosis. Eight hundred and seventy-eight optical

  4. Reflectance and Thermal Infrared Spectroscopy of Mars: Relationship Between ISM and TES for Compositional Determinations

    Science.gov (United States)

    Boyce, Joseph (Technical Monitor); Mustard, John

    2004-01-01

    Reflectance spectroscopy has demonstrated that high albedo surfaces on Mars contain heavily altered materials with some component of hematite, poorly crystalline ferric oxides, and an undefined silicate matrix. The spectral properties of many low albedo regions indicate crystalline basalts containing both low and high calcium pyroxene, a mineralogy consistent with the basaltic SNC meteorites. The Thermal Emission Spectrometer (TES) experiment on the Mars Geochemical Surveyor has acquired critical new data relevant to surface composition and mineralogy, but in a wavelength region that is complementary to reflectance spectroscopy. The essence of the completed research was to analyze TES data in the context of reflectance data obtained by the French ISM imaging spectrometer experiment in 1989. This approach increased our understanding of the complementary nature of these wavelength regions for mineralogic determinations using actual observations of the martian surface. The research effort focused on three regions of scientific importance: Syrtis Major-Isidis Basin, Oxia Palus-Arabia, and Valles Marineris. In each region distinct spatial variations related to reflectance, and in derived mineralogic information and interpreted compositional units were analyzed. In addition, specific science questions related to the composition of volcanics and crustal evolution, soil compositions and pedogenic processes, and the relationship between pristine lithologies and weathering provided an overall science-driven framework for the work. The detailed work plan involved colocation of TES and ISM data, extraction of reflectance and emissivity spectra from areas of known reflectance variability, and quantitative analysis using factor analysis and statistical techniques to determine the degree of correspondence between these different wavelength regions. Identified coherent variations in TES spectroscopy were assessed against known atmospheric effects to validate that the variations

  5. Probing near-normally propagating bulk acoustic waves using pseudo-reflection geometry Brillouin spectroscopy

    Science.gov (United States)

    Parsons, L. C.; Andrews, G. T.

    2012-09-01

    Pseudo-reflection geometry Brillouin spectroscopy can be used to probe acoustic wave dispersion approximately along the surface normal of a material system while avoiding the difficulties associated with specularly reflected light encountered in an ideal reflection configuration. As an example of its application, we show analytically that it can be used to determine both the refractive index and bulk acoustic mode velocities of optically-isotropic non-metallic materials and confirm the utility of the approach via a series of experiments on fused quartz, gallium phosphide, water, and porous silicon films.

  6. Diffuse Reflectance Spectroscopy of Human Skin Using a Commercial Fiber Optic Spectrometer

    International Nuclear Information System (INIS)

    Atencio, J. A. Delgado; Rodriguez, M. Cunill; Montiel, S. Vazquez y; Castro, Jorge; Rodriguez, A. Cornejo; Gutierrez, J. L.; Martinez, F.; Gutierrez, B.; Orozco, E.

    2008-01-01

    Diffuse reflectance spectroscopy is a reliable and easy to implement technique in human tissue characterization. In this work we evaluate the performance of the commercial USB4000 miniature fiber optic spectrometer in the in-vivo measurement of the diffuse reflectance spectra of different healthy skin sites and lesions in a population of 54 volunteers. Results show, that this spectrometer reproduces well the typical signatures of skin spectra over the 400-1000 nm region. Remarkable spectral differences exist between lesions and normal surrounding skin. A diffusion-based model was used to simulate reflectance spectra collected by the optical probe of the system

  7. Characterization of European Lacquers by Terahertz (THz) Reflectometric Imaging

    DEFF Research Database (Denmark)

    Dandolo, Corinna Ludovica Koch; Jepsen, Peter Uhd; Christensen, Mads C.

    2013-01-01

    In this study a European lacquerware replica has been investigated by terahertz (THz) reflectometric imaging. The inspected lacquerware is a wooden panel covered by multiple complex layers of lacquers and plaster. Utilizing pulsed Terahertz Time-Domain Imaging (THz-TDI) in reflection mode, we obs...

  8. Charge carrier mobility in poly[methyl(phenyl)silylene] studied by time-resolved terahertz spectroscopy and molecular modeling

    Czech Academy of Sciences Publication Activity Database

    Němec, Hynek; Kratochvílová, Irena; Kužel, Petr; Šebera, Jakub; Kochalska, Anna; Nožár, Juraj; Nešpůrek, Stanislav

    2011-01-01

    Roč. 13, č. 7 (2011), s. 2850-2856 ISSN 1463-9076 R&D Projects: GA ČR(CZ) GP202/09/P099; GA ČR GA203/08/1594; GA AV ČR KAN401770651; GA MŠk LC512; GA ČR(CZ) GAP304/10/1951 Institutional research plan: CEZ:AV0Z10100520; CEZ:AV0Z40500505 Keywords : molecular electronics * THz spectroscopy * charge carrier mobility Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.573, year: 2011

  9. Wall reflection modeling for charge exchange recombination spectroscopy (CXRS) measurements on Textor and ITER

    International Nuclear Information System (INIS)

    Banerjee, Santanu; Vasu, P; Von Hellermann, M; Jaspers, R J E

    2010-01-01

    Contamination of optical signals by reflections from the tokamak vessel wall is a matter of great concern. For machines such as ITER and future reactors, where the vessel wall will be predominantly metallic, this is potentially a risk factor for quantitative optical emission spectroscopy. This is, in particular, the case when bremsstrahlung continuum radiation from the bulk plasma is used as a common reference light source for the cross-calibration of visible spectroscopy. In this paper the reflected contribution to the continuum level in Textor and ITER has been estimated for the detection channels meant for charge exchange recombination spectroscopy (CXRS). A model assuming diffuse reflection has been developed for the bremsstrahlung which is a much extended source. Based on this model, it is shown that in the case of ITER upper port 3, a wall with a moderate reflectivity of 20% leads to the wall reflected fraction being as high as 55-60% of the weak signals in the edge channels. In contrast, a complete bidirectional reflectance distribution function (BRDF) based model has been developed in order to estimate the reflections from more localized sources like the charge exchange (CX) emission from a neutral beam in tokamaks. The largest signal contamination of ∼15% is seen in the core CX channels, where the true CX signal level is much lower than that in the edge channels. Similar values are obtained for Textor also. These results indicate that the contributions from wall reflections may be large enough to significantly distort the overall spectral features of CX data, warranting an analysis at different wavelengths.

  10. Wall reflection modeling for charge exchange recombination spectroscopy (CXRS) measurements on Textor and ITER

    Energy Technology Data Exchange (ETDEWEB)

    Banerjee, Santanu; Vasu, P [Institute for Plasma Research, Bhat, Gandhinagar 382 428, Gujarat (India); Von Hellermann, M [FOM Institute for Plasma Physics, Rijnhuizen (Netherlands); Jaspers, R J E, E-mail: sbanerje@ipr.res.i [Applied Physics Department, Eindhoven University of Technology, Eindhoven (Netherlands)

    2010-12-15

    Contamination of optical signals by reflections from the tokamak vessel wall is a matter of great concern. For machines such as ITER and future reactors, where the vessel wall will be predominantly metallic, this is potentially a risk factor for quantitative optical emission spectroscopy. This is, in particular, the case when bremsstrahlung continuum radiation from the bulk plasma is used as a common reference light source for the cross-calibration of visible spectroscopy. In this paper the reflected contribution to the continuum level in Textor and ITER has been estimated for the detection channels meant for charge exchange recombination spectroscopy (CXRS). A model assuming diffuse reflection has been developed for the bremsstrahlung which is a much extended source. Based on this model, it is shown that in the case of ITER upper port 3, a wall with a moderate reflectivity of 20% leads to the wall reflected fraction being as high as 55-60% of the weak signals in the edge channels. In contrast, a complete bidirectional reflectance distribution function (BRDF) based model has been developed in order to estimate the reflections from more localized sources like the charge exchange (CX) emission from a neutral beam in tokamaks. The largest signal contamination of {approx}15% is seen in the core CX channels, where the true CX signal level is much lower than that in the edge channels. Similar values are obtained for Textor also. These results indicate that the contributions from wall reflections may be large enough to significantly distort the overall spectral features of CX data, warranting an analysis at different wavelengths.

  11. Freeform Fabrication of Magnetophotonic Crystals with Diamond Lattices of Oxide and Metallic Glasses for Terahertz Wave Control by Micro Patterning Stereolithography and Low Temperature Sintering

    Directory of Open Access Journals (Sweden)

    Maasa Nakano

    2013-04-01

    Full Text Available Micrometer order magnetophotonic crystals with periodic arranged metallic glass and oxide glass composite materials were fabricated by stereolithographic method to reflect electromagnetic waves in terahertz frequency ranges through Bragg diffraction. In the fabrication process, the photo sensitive acrylic resin paste mixed with micrometer sized metallic glass of Fe72B14.4Si9.6Nb4 and oxide glass of B2O3·Bi2O3 particles was spread on a metal substrate, and cross sectional images of ultra violet ray were exposed. Through the layer by layer stacking, micro lattice structures with a diamond type periodic arrangement were successfully formed. The composite structures could be obtained through the dewaxing and sintering process with the lower temperature under the transition point of metallic glass. Transmission spectra of the terahertz waves through the magnetophotonic crystals were measured by using a terahertz time domain spectroscopy.

  12. Diagnosis of oral lichen planus from analysis of saliva samples using terahertz time-domain spectroscopy and chemometrics

    Science.gov (United States)

    Kistenev, Yury V.; Borisov, Alexey V.; Titarenko, Maria A.; Baydik, Olga D.; Shapovalov, Alexander V.

    2018-04-01

    The ability to diagnose oral lichen planus (OLP) based on saliva analysis using THz time-domain spectroscopy and chemometrics is discussed. The study involved 30 patients (2 male and 28 female) with OLP. This group consisted of two subgroups with the erosive form of OLP (n = 15) and with the reticular and papular forms of OLP (n = 15). The control group consisted of six healthy volunteers (one male and five females) without inflammation in the mucous membrane in the oral cavity and without periodontitis. Principal component analysis was used to reveal informative features in the experimental data. The one-versus-one multiclass classifier using support vector machine binary classifiers was used. The two-stage classification approach using several absorption spectra scans for an individual saliva sample provided 100% accuracy of differential classification between OLP subgroups and control group.

  13. Excitations and relaxation dynamics in multiferroic GeV4S8 studied by terahertz and dielectric spectroscopy

    Science.gov (United States)

    Reschke, S.; Wang, Zhe; Mayr, F.; Ruff, E.; Lunkenheimer, P.; Tsurkan, V.; Loidl, A.

    2017-10-01

    We report on THz time-domain spectroscopy on multiferroic GeV4S8 , which undergoes orbital ordering at a Jahn-Teller transition at 30.5 K and exhibits antiferromagnetic order below 14.6 K. The THz experiments are complemented by dielectric experiments at audio and radio frequencies. We identify a low-lying excitation close to 0.5 THz, which is only weakly temperature dependent and probably corresponds to a molecular excitation within the electronic level scheme of the V4 clusters. In addition, we detect complex temperature-dependent behavior of a low-lying phononic excitation, closely linked to the onset of orbitally driven ferroelectricity. In the high-temperature cubic phase, which is paramagnetic and orbitally disordered, this excitation is of relaxational character becomes an overdamped Lorentzian mode in the orbitally ordered phase below the Jahn-Teller transition, and finally appears as well-defined phonon excitation in the antiferromagnetic state. Abrupt changes in the real and imaginary parts of the complex dielectric permittivity show that orbital ordering appears via a structural phase transition with strong first-order character and that the onset of antiferromagnetic order is accompanied by significant structural changes, which are of first-order character, too. Dielectric spectroscopy documents that at low frequencies, significant dipolar relaxations are present in the orbitally ordered, paramagnetic phase only. In contrast to the closely related GaV4S8 , this relaxation dynamics that most likely mirrors coupled orbital and polar fluctuations does not seem to be related to the dynamic processes detected in the THz regime.

  14. Terahertz transport dynamics of graphene charge carriers

    DEFF Research Database (Denmark)

    Buron, Jonas Christian Due

    The electronic transport dynamics of graphene charge carriers at femtosecond (10-15 s) to picosecond (10-12 s) time scales are investigated using terahertz (1012 Hz) time-domain spectroscopy (THz-TDS). The technique uses sub-picosecond pulses of electromagnetic radiation to gauge the electrodynamic...... response of thin conducting films at up to multi-terahertz frequencies. In this thesis THz-TDS is applied towards two main goals; (1) investigation of the fundamental carrier transport dynamics in graphene at femtosecond to picosecond timescales and (2) application of terahertz time-domain spectroscopy...... to rapid and non-contact electrical characterization of large-area graphene, relevant for industrial integration. We show that THz-TDS is an accurate and reliable probe of graphene sheet conductance, and that the technique provides insight into fundamental aspects of the nanoscopic nature of conduction...

  15. Quantification of hemoglobin and its derivatives in oral cancer diagnosis by diffuse reflectance spectroscopy

    Science.gov (United States)

    Kaniyappan, Udayakumar; Gnanatheepam, Einstein; Aruna, Prakasarao; Dornadula, Koteeswaran; Ganesan, Singaravelu

    2017-02-01

    Cancer is one of the most common threat to human beings and it increases at an alarming level around the globe. In recent years, due to the advancements in opto-electronic technology, various optical spectroscopy techniques have emerged to assess the photophysicochemical and morphological conditions of normal and malignant tissues in micro as well as in macroscopic scale. In this regard, diffuse reflectance spectroscopy is considered to be the simplest, cost effective and rapid technique in diagnosis of cancerous tissues. In the present study, the hemoglobin concentration in normal and cancerous oral tissues was quantified and subsequent statistical analysis has been carried out to verify the diagnostic potentiality of the technique.

  16. Highly accurate thickness measurement of multi-layered automotive paints using terahertz technology

    Science.gov (United States)

    Krimi, Soufiene; Klier, Jens; Jonuscheit, Joachim; von Freymann, Georg; Urbansky, Ralph; Beigang, René

    2016-07-01

    In this contribution, we present a highly accurate approach for thickness measurements of multi-layered automotive paints using terahertz time domain spectroscopy in reflection geometry. The proposed method combines the benefits of a model-based material parameters extraction method to calibrate the paint coatings, a generalized Rouard's method to simulate the terahertz radiation behavior within arbitrary thin films, and the robustness of a powerful evolutionary optimization algorithm to increase the sensitivity of the minimum thickness measurement limit. Within the framework of this work, a self-calibration model is introduced, which takes into consideration the real industrial challenges such as the effect of wet-on-wet spray in the painting process.

  17. Highly accurate thickness measurement of multi-layered automotive paints using terahertz technology

    International Nuclear Information System (INIS)

    Krimi, Soufiene; Beigang, René; Klier, Jens; Jonuscheit, Joachim; Freymann, Georg von; Urbansky, Ralph

    2016-01-01

    In this contribution, we present a highly accurate approach for thickness measurements of multi-layered automotive paints using terahertz time domain spectroscopy in reflection geometry. The proposed method combines the benefits of a model-based material parameters extraction method to calibrate the paint coatings, a generalized Rouard's method to simulate the terahertz radiation behavior within arbitrary thin films, and the robustness of a powerful evolutionary optimization algorithm to increase the sensitivity of the minimum thickness measurement limit. Within the framework of this work, a self-calibration model is introduced, which takes into consideration the real industrial challenges such as the effect of wet-on-wet spray in the painting process.

  18. Terahertz polarizing beam splitter based on copper grating on polyimide substrate

    Science.gov (United States)

    Zhang, Mengen; Li, Xiangjun; Wang, Wentao; Liu, Jianjun; Hong, Zhi

    2012-12-01

    A terahertz polarizing beam splitter, based on a copper grating on polyimide (PI) substrate, was fabricated by the way of laser induced and non-electrolytic plating. The good polarization characteristics of the splitter in the range of 0°-180°polarization are verified experimentally using backward wave oscillator at fixed frequency of 300GHz, and the insertion losses of 0.13dB and 0.32dB are measured for the transmitted and reflected beams, respectively. The broadband transmission of TM wave of the splitter was also measured by terahertz time-domain spectroscopy, and the extinction ratio larger than 22dB is obtained in the frequency range of 0.2-1.5THz. The experiment results are in good agreement with finite element simulation results.

  19. Analysis of bacteria on steel surfaces using reflectance micro-Fourier transform infrared spectroscopy.

    Science.gov (United States)

    Ojeda, Jesús J; Romero-González, María E; Banwart, Steven A

    2009-08-01

    Reflectance micro-Fourier transform infrared (FT-IR) analysis has been applied to characterize biofilm formation of Aquabacterium commune, a common microorganism present on drinking water distribution systems, onto the increasingly popular pipe material stainless steel EN1.4307. The applicability of the reflectance micro-FT-IR technique for analyzing the bacterial functional groups is discussed, and the results are compared to spectra obtained using more conventional FT-IR techniques: transmission micro-FT-IR, attenuated transmitted reflectance (ATR), and KBr pellets. The differences between the infrared spectra of wet and dried bacteria, as well as free versus attached bacteria, are also discussed. The spectra obtained using reflectance micro-FT-IR spectroscopy were comparable to those obtained using other FT-IR techniques. The absence of sample preparation, the potential to analyze intact samples, and the ability to characterize opaque and thick samples without the need to transfer the bacterial samples to an infrared transparent medium or produce a pure culture were the main advantages of reflectance micro-FT-IR spectroscopy.

  20. Preparation, characterization, Raman, and terahertz spectroscopy study on carbon nanotubes, graphene nano-sheets, and onion like carbon materials

    International Nuclear Information System (INIS)

    Abouelsayed, A.; Anis, Badawi; Hassaballa, Safwat; Khalil, Ahmed S.G.; Rashed, Usama M.; Eid, Kamal A.; Al-Ashkar, Emad; El hotaby, W.

    2017-01-01

    We present the optical properties of carbon nanotubes, graphene nanosheets, and onion like carbon (OLC) samples with different cages size in wide frequency range from 0.06 to 1650 THz. The samples were characterized by high resolution transmission electron microscope (HRTEM), Raman, and UV–Vis-IR-THz spectroscopy. The broad absorption bands centered at around 10, 3, 2.5, 1.5, and 1.8 THz for SWCNTs, MWCNTs, graphene nanosheets, large cages (OLC 1 ), and small cages (OLC 2 ) samples, respectively, are assigned to plasmon resonance due to the localization of free carriers in a finite length. For SWCNTs, both the plasmon band position and the Drude weight (D) are located at higher values as compared with MWCNTs, graphene nanosheets, and OLC sample, suggesting that the dimensionality of the system plays a major role regarding the carrier mobility of the graphene structure. The differences in the estimated values of D, the Fermi energy (E f ), and density of carriers (N) in case of OLC samples can be due to the variation in sizes of the cages and the variation of the defects in the structure of the outermost layers of cages, where each cages consist of multi-layers of graphene enclosed one into another. - Highlights: • Preparation and spectroscopic studies on carbonaceous materials were performed. • Drude-Lorentz model were used for fitting the optical conductivity spectra. • The plasmonic resonances have been observed in THz frequency range. • The charge density N has been effected by disordered of the grapheme structure. • The σ DC values is decreased in case of 2D carbonaceous materials.

  1. Preparation, characterization, Raman, and terahertz spectroscopy study on carbon nanotubes, graphene nano-sheets, and onion like carbon materials

    Energy Technology Data Exchange (ETDEWEB)

    Abouelsayed, A., E-mail: as.abouelsayed@gmail.com [Spectroscopy Department, Physics Division, National Research Centre, 33 El Bohouth St. (fromer El Tahrir St.), Dokki, P.O. 12622, Giza (Egypt); Anis, Badawi [Spectroscopy Department, Physics Division, National Research Centre, 33 El Bohouth St. (fromer El Tahrir St.), Dokki, P.O. 12622, Giza (Egypt); Hassaballa, Safwat [Physics Department, Faculty of Science, Al-Azhar University, Cairo 11884 (Egypt); Khalil, Ahmed S.G. [Center for Environmental and Smart Technology, Fayoum University, Fayoum (Egypt); Egypt Nanotechnology Center, Cairo University, Giza (Egypt); Arab Academy for Science, Technology and Maritime Transport, Smart Village Campus, Giza (Egypt); Rashed, Usama M. [Physics Department, Faculty of Science, Al-Azhar University, Cairo 11884 (Egypt); Eid, Kamal A.; Al-Ashkar, Emad; El hotaby, W. [Spectroscopy Department, Physics Division, National Research Centre, 33 El Bohouth St. (fromer El Tahrir St.), Dokki, P.O. 12622, Giza (Egypt)

    2017-03-01

    We present the optical properties of carbon nanotubes, graphene nanosheets, and onion like carbon (OLC) samples with different cages size in wide frequency range from 0.06 to 1650 THz. The samples were characterized by high resolution transmission electron microscope (HRTEM), Raman, and UV–Vis-IR-THz spectroscopy. The broad absorption bands centered at around 10, 3, 2.5, 1.5, and 1.8 THz for SWCNTs, MWCNTs, graphene nanosheets, large cages (OLC{sub 1}), and small cages (OLC{sub 2}) samples, respectively, are assigned to plasmon resonance due to the localization of free carriers in a finite length. For SWCNTs, both the plasmon band position and the Drude weight (D) are located at higher values as compared with MWCNTs, graphene nanosheets, and OLC sample, suggesting that the dimensionality of the system plays a major role regarding the carrier mobility of the graphene structure. The differences in the estimated values of D, the Fermi energy (E{sub f}), and density of carriers (N) in case of OLC samples can be due to the variation in sizes of the cages and the variation of the defects in the structure of the outermost layers of cages, where each cages consist of multi-layers of graphene enclosed one into another. - Highlights: • Preparation and spectroscopic studies on carbonaceous materials were performed. • Drude-Lorentz model were used for fitting the optical conductivity spectra. • The plasmonic resonances have been observed in THz frequency range. • The charge density N has been effected by disordered of the grapheme structure. • The σ{sub DC} values is decreased in case of 2D carbonaceous materials.

  2. [Application of Fourier transform attenuated total reflection infrared spectroscopy in analysis of pulp and paper industry].

    Science.gov (United States)

    Zhang, Yong; Cao, Chun-yu; Feng, Wen-ying; Xu, Ming; Su, Zhen-hua; Liu, Xiao-meng; Lü, Wei-jun

    2011-03-01

    As one of the most powerful tools to investigate the compositions of raw materials and the property of pulp and paper, infrared spectroscopy has played an important role in pulp and paper industry. However, the traditional transmission infrared spectroscopy has not met the requirements of the producing processes because of its disadvantages of time consuming and sample destruction. New technique would be needed to be found. Fourier transform attenuated total reflection infrared spectroscopy (ATR-FTIR) is an advanced spectroscopic tool for nondestructive evaluation and could rapidly, accurately estimate the production properties of each process in pulp and paper industry. The present review describes the application of ATR-FTIR in analysis of pulp and paper industry. The analysis processes will include: pulping, papermaking, environmental protecting, special processing and paper identifying.

  3. Measurement of the enzymes lactate dehydrogenase and creatine kinase using reflectance spectroscopy and reagent strips.

    OpenAIRE

    Stevens, J F; Tsang, W; Newall, R G

    1983-01-01

    Two new methods for the assay of total activities of lactate dehydrogenase and creatine kinase are described, in which the enzyme activities are measured from a solid-state reagent strip during a kinetic reaction, the reaction being monitored in the ultra-violet region of the spectrum by reflectance spectroscopy. The performances of these methods are evaluated, and compared to conventional "wet" chemistry methods. The solid-phase reagent methods demonstrated precision and accuracy acceptable ...

  4. Trasmission and Reflection (ATR)Far-Infrared Spectroscopy Applied in the Analysis of Cultural Heritage Materials

    OpenAIRE

    Kendix, Elsebeth Langholz

    2009-01-01

    FIR spectroscopy is an alternative way of collecting spectra of many inorganic pigments and corrosion products found on art objects, which is not normally observed in the MIR region. Most FIR spectra are traditionally collected in transmission mode but as a real novelty it is now also possible to record FIR spectra in ATR (Attenuated Total Reflectance) mode. In FIR transmission we employ polyethylene (PE) for preparation of pellets by embedding the sample in PE. Unfortunately, ...

  5. Multiple spatially resolved reflection spectroscopy for in vivo determination of carotenoids in human skin and blood

    Science.gov (United States)

    Darvin, Maxim E.; Magnussen, Björn; Lademann, Juergen; Köcher, Wolfgang

    2016-09-01

    Non-invasive measurement of carotenoid antioxidants in human skin is one of the important tasks to investigate the skin physiology in vivo. Resonance Raman spectroscopy and reflection spectroscopy are the most frequently used non-invasive techniques in dermatology and skin physiology. In the present study, an improved method based on multiple spatially resolved reflection spectroscopy (MSRRS) was introduced. The results obtained were compared with those obtained using the ‘gold standard’ resonance Raman spectroscopy method and showed strong correlations for the total carotenoid concentration (R  =  0.83) as well as for lycopene (R  =  0.80). The measurement stability was confirmed to be better than 10% within the total temperature range from 5 °C to  +  30 °C and pressure contact between the skin and the MSRRS sensor from 800 Pa to 18 000 Pa. In addition, blood samples taken from the subjects were analyzed for carotenoid concentrations. The MSRRS sensor was calibrated on the blood carotenoid concentrations resulting in being able to predict with a correlation of R  =  0.79. On the basis of blood carotenoids it could be demonstrated that the MSRRS cutaneous measurements are not influenced by Fitzpatrick skin types I-VI. The MSRRS sensor is commercially available under the brand name biozoom.

  6. Angle-resolved reflection spectroscopy of high-quality PMMA opal crystal

    Science.gov (United States)

    Nemtsev, Ivan V.; Tambasov, Igor A.; Ivanenko, Alexander A.; Zyryanov, Victor Ya.

    2018-02-01

    PMMA opal crystal was prepared by a simple hybrid method, which includes sedimentation, meniscus formation and evaporation. We investigated three surfaces of this crystal by angle-resolved reflective light spectroscopy and SEM study. The angle-resolved reflective measurements were carried out in the 400-1100 nm range. We have determined the high-quality ordered surface of the crystal region. Narrow particle size distribution of the surface has been revealed. The average particle diameter obtained with SEM was nearly 361 nm. The most interesting result was that reflectivity of the surface turned out up to 98% at normal light incidence. Using a fit of dependences of the maximum reflectivity wavelength from an angle based on the Bragg-Snell law, the wavelength of maximum 0° reflectivity, the particle diameter and the fill factor have been determined. For the best surface maximum reflectivity wavelength of a 0° angle was estimated to be 869 nm. The particle diameter and fill factor were calculated as 372 nm and 0.8715, respectively. The diameter obtained by fitting is in excellent agreement with the particle diameter obtained with SEM. The reflectivity maximum is assumed to increase significantly when increasing the fill factor. We believe that using our simple approach to manufacture PMMA opal crystals will significantly increase the fabrication of high-quality photonic crystal templates and thin films.

  7. Prediction of tablets disintegration times using near-infrared diffuse reflectance spectroscopy as a nondestructive method.

    Science.gov (United States)

    Donoso, M; Ghaly, Evone S

    2005-01-01

    The goals of this study are to user near-infrared reflectance (NIR) spectroscopy to measure the disintegration time of a series of tablets compacted at different compressional forces, calibrate NIR data vs. laboratory equipment data, develop a model equation, validate the model, and test the model's predictive ability. Seven theophylline tablet formulations of the same composition but with different disintegration time values (0.224, 1.141, 2.797, 5.492, 9.397, 16.8, and 30.092 min) were prepared along with five placebo tablet formulations with different disintegration times. Laboratory disintegration time was compared to near-infrared diffuse reflectance data. Linear regression, quadratic, cubic, and partial least square techniques were used to determine the relationship between disintegration time and near-infrared spectra. The results demonstrated that an increase in disintegration time produced an increase in near-infrared absorbance. Series of model equations, which depended on the mathematical technique used for regression, were developed from the calibration of disintegration time using laboratory equipment vs. the near-infrared diffuse reflectance for each formulation. The results of NIR disintegration time were similar to laboratory tests. The near-infrared diffuse reflectance spectroscopy method is an alternative nondestructive method for measurement of disintegration time of tablets.

  8. Bulk-like transverse electron mobility in an array of heavily n-doped InP nanowires probed by terahertz spectroscopy

    Czech Academy of Sciences Publication Activity Database

    Ponseca jr., C.S.; Němec, Hynek; Wallentin, J.; Anttu, N.; Beech, J.P.; Iqbal, A.; Borgström, M.; Pistol, M.-E.; Samuelson, L.; Yartsev, A.

    2014-01-01

    Roč. 90, č. 8 (2014), "085405-1"-"085405-7" ISSN 1098-0121 R&D Projects: GA ČR GA13-12386S Grant - others:AVČR(CZ) M100101218 Institutional support: RVO:68378271 Keywords : time-resolved terahertz spectrocopy * semiconductor nanostructures * mobility * effective medium Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.736, year: 2014

  9. Guided Terahertz Waves for Characterizing Explosives

    Science.gov (United States)

    2009-01-01

    Spectroscopy of Nanometer Water Layers,” Optics Letters 29, 1617–1619 (2004). 4 J. S. Melinger, N. Laman , S. Sree Harsha, and D. Grischkowsky, “Line...2006). 5 N. Laman , S. Sree Harsha, D. Grischkowsky, and J.S. Melinger, “7 GHz Resolution Waveguide THz Spectroscopy of Explosives Related Solids...Showing New Features,” Optics Express 16, 4094–4105 (2008). 6 J.S. Melinger, N. Laman , and D. Grischkowsky, “The Underlying Terahertz Vibrational

  10. In situ differential reflectance spectroscopy of thin crystalline films of PTCDA on different substrates

    International Nuclear Information System (INIS)

    Proehl, Holger; Nitsche, Robert; Dienel, Thomas; Leo, Karl; Fritz, Torsten

    2005-01-01

    We report an investigation of the excitonic properties of thin crystalline films of the archetypal organic semiconductor PTCDA (3,4,9,10-perylenetetracarboxylic dianhydride) grown on poly- and single crystalline surfaces. A sensitive setup capable of measuring the optical properties of ultrathin organic molecular crystals via differential reflectance spectroscopy (DRS) is presented. This tool allows to carry out measurements in situ, i.e., during the actual film growth, and over a wide spectral range, even on single crystalline surfaces with high symmetry or metallic surfaces, where widely used techniques like reflection anisotropy spectroscopy (RAS) or fluorescence excitation spectroscopy fail. The spectra obtained by DRS resemble mainly the absorption of the films if transparent substrates are used, which simplifies the analysis. In the case of mono- to multilayer films of PTCDA on single crystalline muscovite mica(0001) and Au(111) substrates, the formation of the solid state absorption from monomer to dimer and further to crystal-like absorption spectra can be monitored

  11. Fiber optics reflectance spectroscopy (45°x: 45°) for color analysis of dental composite.

    Science.gov (United States)

    Gargano, Marco; Ludwig, Nicola; Federighi, Veronica; Sykes, Ros; Lodi, Giovanni; Sardella, Andrea; Carrassi, Antonio; Varoni, Elena M

    2016-08-01

    To evaluate the application of a fiber optic reflectance spectroscopy (FORS) prototype probe for 45°x: 45° FORS for determining color of dental materials. A portable spectrophotometer with a highly manageable fiber optics co-axial probe was used to apply 45°x: 45° FORS for color matching in restorative dentistry. The color coordinates in CIELAB space of two dental shade guides and of the corresponding photopolymerized composites were collected and compared. The 45°x: 45° FORS with the co-axial probe (test system), the integrating sphere spectroscopy (reference system) and a commercial dental colorimeter (comparator system) were used to collect data and calculate color differences (ΔE and ΔE00). FORS system displayed high repeatability, reproducibility and accuracy. ΔE and ΔE00 values between the shade-guide, each other, and the corresponding composites resulted above the clinically acceptable limit. The 45°x: 45° FORS test system demonstrated suitable in vitro performance for dental composite color evaluation. 45°x: 45° fiber optic reflectance spectroscopy allows reliable color analysis of small surfaces of dental composites, favoring the color matching of material with the closely surrounding dental tissue, and confirming significant color differences between shade guide tabs and photo-polymerized composites.

  12. Convergence of Terahertz Sciences in Biomedical Systems

    CERN Document Server

    Kim, Yong; Han, Haewook; Han, Joon; Ahn, Jaewook; Son, Joo-Hiuk; Park, Woong-Yang; Jeong, Young

    2012-01-01

    Recent technological breakthrough in the field of Terahertz radiation has triggered new applications in biology and biomedicine. Particularly, biological applications are based on the specific spectroscopic fingerprints of biological matter in this spectral region. Historically with the discovery of new electromagnetic wave spectrum, we have always discovered new medical diagnostic imaging systems. The use of terahertz wave was not realized due to the absence of useful terahertz sources. Now after successful generation of THz waves, it is reported that a great potential for THz wave exists for its resonance with bio-molecules. There are many challenging issues such as development of THz passive and active instrumentations, understanding of THz-Bio interaction for THz spectroscopy, THz-Bio nonlinear phenomena and safety guideline, and THz imaging systems. Eventually the deeper understanding of THz-Bio interaction and novel THz systems enable us to develop powerful THz biomedical imaging systems which can contr...

  13. Portable, Fiber-Based, Diffuse Reflection Spectroscopy (DRS) Systems for Estimating Tissue Optical Properties.

    Science.gov (United States)

    Vishwanath, Karthik; Chang, Kevin; Klein, Daniel; Deng, Yu Feng; Chang, Vivide; Phelps, Janelle E; Ramanujam, Nimmi

    2011-02-01

    Steady-state diffuse reflection spectroscopy is a well-studied optical technique that can provide a noninvasive and quantitative method for characterizing the absorption and scattering properties of biological tissues. Here, we compare three fiber-based diffuse reflection spectroscopy systems that were assembled to create a light-weight, portable, and robust optical spectrometer that could be easily translated for repeated and reliable use in mobile settings. The three systems were built using a broadband light source and a compact, commercially available spectrograph. We tested two different light sources and two spectrographs (manufactured by two different vendors). The assembled systems were characterized by their signal-to-noise ratios, the source-intensity drifts, and detector linearity. We quantified the performance of these instruments in extracting optical properties from diffuse reflectance spectra in tissue-mimicking liquid phantoms with well-controlled optical absorption and scattering coefficients. We show that all assembled systems were able to extract the optical absorption and scattering properties with errors less than 10%, while providing greater than ten-fold decrease in footprint and cost (relative to a previously well-characterized and widely used commercial system). Finally, we demonstrate the use of these small systems to measure optical biomarkers in vivo in a small-animal model cancer therapy study. We show that optical measurements from the simple portable system provide estimates of tumor oxygen saturation similar to those detected using the commercial system in murine tumor models of head and neck cancer.

  14. Diffuse reflectance spectroscopy for monitoring diabetic foot ulcer - A pilot study

    Science.gov (United States)

    Anand, Suresh; Sujatha, N.; Narayanamurthy, V. B.; Seshadri, V.; Poddar, Richa

    2014-02-01

    Foot ulceration due to diabetes mellitus is a major problem affecting 12-25% of diabetic subjects in their lifetime. An untreated ulcer further gets infected which causes necrosis leading to amputation of lower extremities. Early identification of risk factors and treatment for these chronic wounds would reduce health care costs and improve the quality of life for people with diabetes. Recent clinical investigations have shown that a series of factors including reduced oxygen delivery and disturbed metabolism have been observed on patients with foot ulceration due to diabetes. Also, these factors can impair the wound healing process. Optical techniques based on diffuse reflectance spectroscopy provide characteristic spectral finger prints shed light on tissue oxygenation levels and morphological composition of a tissue. This study deals with the application of diffuse reflectance intensity ratios based on oxyhemoglobin bands (R542/R580), ratios of oxy- and deoxy-hemoglobin bands (R580/R555), total hemoglobin concentration and hemoglobin oxygen saturation between normal and diabetic foot ulcer sites. Preliminary results obtained are found to be promising indicating the application of reflectance spectroscopy in the assessment of foot ulcer healing.

  15. A library based fitting method for visual reflectance spectroscopy of human skin

    Energy Technology Data Exchange (ETDEWEB)

    Verkruysse, Wim [Beckman Laser Institute, University of California, Irvine, CA 92612 (United States); Zhang Rong [Beckman Laser Institute, University of California, Irvine, CA 92612 (United States); Choi, Bernard [Beckman Laser Institute, University of California, Irvine, CA 92612 (United States); Lucassen, Gerald [Personal Care Institute, Philips Research, Prof Holstlaan 4, Eindhoven (Netherlands); Svaasand, Lars O [Department of Physical Electronics Norwegian University of Science and Technology, N-7491 Trondheim (Norway); Nelson, J Stuart [Beckman Laser Institute, University of California, Irvine, CA 92612 (United States)

    2005-01-07

    The diffuse reflectance spectrum of human skin in the visible region (400-800 nm) contains information on the concentrations of chromophores such as melanin and haemoglobin. This information may be extracted by fitting the reflectance spectrum with an optical diffusion based analytical expression applied to a layered skin model. With the use of the analytical expression, it is assumed that light transport is dominated by scattering. For port wine stain (PWS) and highly pigmented human skin, however, this assumption may not be valid resulting in a potentially large error in visual reflectance spectroscopy (VRS). Monte Carlo based techniques can overcome this problem but are currently too computationally intensive to be combined with previously used fitting procedures. The fitting procedure presented herein is based on a library search which enables the use of accurate reflectance spectra based on forward Monte Carlo simulations or diffusion theory. This allows for accurate VRS to characterize chromophore concentrations in PWS and highly pigmented human skin. The method is demonstrated using both simulated and measured reflectance spectra. An additional advantage of the method is that the fitting procedure is very fast.

  16. A library based fitting method for visual reflectance spectroscopy of human skin

    International Nuclear Information System (INIS)

    Verkruysse, Wim; Zhang Rong; Choi, Bernard; Lucassen, Gerald; Svaasand, Lars O; Nelson, J Stuart

    2005-01-01

    The diffuse reflectance spectrum of human skin in the visible region (400-800 nm) contains information on the concentrations of chromophores such as melanin and haemoglobin. This information may be extracted by fitting the reflectance spectrum with an optical diffusion based analytical expression applied to a layered skin model. With the use of the analytical expression, it is assumed that light transport is dominated by scattering. For port wine stain (PWS) and highly pigmented human skin, however, this assumption may not be valid resulting in a potentially large error in visual reflectance spectroscopy (VRS). Monte Carlo based techniques can overcome this problem but are currently too computationally intensive to be combined with previously used fitting procedures. The fitting procedure presented herein is based on a library search which enables the use of accurate reflectance spectra based on forward Monte Carlo simulations or diffusion theory. This allows for accurate VRS to characterize chromophore concentrations in PWS and highly pigmented human skin. The method is demonstrated using both simulated and measured reflectance spectra. An additional advantage of the method is that the fitting procedure is very fast

  17. A library based fitting method for visual reflectance spectroscopy of human skin

    Science.gov (United States)

    Verkruysse, Wim; Zhang, Rong; Choi, Bernard; Lucassen, Gerald; Svaasand, Lars O.; Nelson, J. Stuart

    2005-01-01

    The diffuse reflectance spectrum of human skin in the visible region (400-800 nm) contains information on the concentrations of chromophores such as melanin and haemoglobin. This information may be extracted by fitting the reflectance spectrum with an optical diffusion based analytical expression applied to a layered skin model. With the use of the analytical expression, it is assumed that light transport is dominated by scattering. For port wine stain (PWS) and highly pigmented human skin, however, this assumption may not be valid resulting in a potentially large error in visual reflectance spectroscopy (VRS). Monte Carlo based techniques can overcome this problem but are currently too computationally intensive to be combined with previously used fitting procedures. The fitting procedure presented herein is based on a library search which enables the use of accurate reflectance spectra based on forward Monte Carlo simulations or diffusion theory. This allows for accurate VRS to characterize chromophore concentrations in PWS and highly pigmented human skin. The method is demonstrated using both simulated and measured reflectance spectra. An additional advantage of the method is that the fitting procedure is very fast.

  18. Terahertz spectral unmixing based method for identifying gastric cancer

    Science.gov (United States)

    Cao, Yuqi; Huang, Pingjie; Li, Xian; Ge, Weiting; Hou, Dibo; Zhang, Guangxin

    2018-02-01

    At present, many researchers are exploring biological tissue inspection using terahertz time-domain spectroscopy (THz-TDS) techniques. In this study, based on a modified hard modeling factor analysis method, terahertz spectral unmixing was applied to investigate the relationships between the absorption spectra in THz-TDS and certain biomarkers of gastric cancer in order to systematically identify gastric cancer. A probability distribution and box plot were used to extract the distinctive peaks that indicate carcinogenesis, and the corresponding weight distributions were used to discriminate the tissue types. The results of this work indicate that terahertz techniques have the potential to detect different levels of cancer, including benign tumors and polyps.

  19. Integrated heterodyne terahertz transceiver

    Science.gov (United States)

    Wanke, Michael C [Albuquerque, NM; Lee, Mark [Albuquerque, NM; Nordquist, Christopher D [Albuquerque, NM; Cich, Michael J [Albuquerque, NM

    2012-09-25

    A heterodyne terahertz transceiver comprises a quantum cascade laser that is integrated on-chip with a Schottky diode mixer. A terahertz signal can be received by an antenna connected to the mixer, an end facet or sidewall of the laser, or through a separate active section that can amplify the incident signal. The quantum cascade laser couples terahertz local oscillator power to the Schottky diode to mix with the received terahertz signal to provide an intermediate frequency output signal. The fully integrated transceiver optimizes power efficiency, sensitivity, compactness, and reliability. The transceiver can be used in compact, fieldable systems covering a wide variety of deployable applications not possible with existing technology.

  20. Integrated heterodyne terahertz transceiver

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Mark [Albuquerque, NM; Wanke, Michael C [Albuquerque, NM

    2009-06-23

    A heterodyne terahertz transceiver comprises a quantum cascade laser that is integrated on-chip with a Schottky diode mixer. An antenna connected to the Schottky diode receives a terahertz signal. The quantum cascade laser couples terahertz local oscillator power to the Schottky diode to mix with the received terahertz signal to provide an intermediate frequency output signal. The fully integrated transceiver optimizes power efficiency, sensitivity, compactness, and reliability. The transceiver can be used in compact, fieldable systems covering a wide variety of deployable applications not possible with existing technology.

  1. Real-time reflectance-difference spectroscopy of GaAs molecular beam epitaxy homoepitaxial growth

    Energy Technology Data Exchange (ETDEWEB)

    Lastras-Martínez, A., E-mail: alm@cactus.iico.uaslp.mx, E-mail: alastras@gmail.com; Ortega-Gallegos, J.; Guevara-Macías, L. E.; Nuñez-Olvera, O.; Balderas-Navarro, R. E.; Lastras-Martínez, L. F. [Instituto de Investigación en Comunicación Optica, Universidad Autónoma de San Luis Potosí, Alvaro Obregón 64, San Luis Potosí, SLP 78000 (Mexico); Lastras-Montaño, L. A. [IBM T. J. Watson Research Center, Yorktown Heights, New York 10598 (United States); Lastras-Montaño, M. A. [Department of Electrical and Computer Engineering, University of California, Santa Barbara, Santa Barbara, California 93106 (United States)

    2014-03-01

    We report on real time-resolved Reflectance-difference (RD) spectroscopy of GaAs(001) grown by molecular beam epitaxy, with a time-resolution of 500 ms per spectrum within the 2.3–4.0 eV photon energy range. Through the analysis of transient RD spectra we demonstrated that RD line shapes are comprised of two components with different physical origins and determined their evolution during growth. Such components were ascribed to the subsurface strain induced by surface reconstruction and to surface stoichiometry. Results reported in this paper render RD spectroscopy as a powerful tool for the study of fundamental processes during the epitaxial growth of zincblende semiconductors.

  2. Real-time reflectance-difference spectroscopy of GaAs molecular beam epitaxy homoepitaxial growth

    Directory of Open Access Journals (Sweden)

    A. Lastras-Martínez

    2014-03-01

    Full Text Available We report on real time-resolved Reflectance-difference (RD spectroscopy of GaAs(001 grown by molecular beam epitaxy, with a time-resolution of 500 ms per spectrum within the 2.3–4.0 eV photon energy range. Through the analysis of transient RD spectra we demonstrated that RD line shapes are comprised of two components with different physical origins and determined their evolution during growth. Such components were ascribed to the subsurface strain induced by surface reconstruction and to surface stoichiometry. Results reported in this paper render RD spectroscopy as a powerful tool for the study of fundamental processes during the epitaxial growth of zincblende semiconductors.

  3. Phthalocyanine identification in paintings by reflectance spectroscopy. A laboratory and in situ study

    Science.gov (United States)

    Poldi, G.; Caglio, S.

    2013-06-01

    The importance of identifying pigments using non invasive (n.i.) analyses has gained increasing importance in the field of spectroscopy applied to art conservation and art studies. Among the large set of pigments synthesized and marketed during 20th century, surely phthalocyanine blue and green pigments occupy an important role in the field of painting (including restoration) and printing, thanks to their characteristics like brightness and fastness. This research focused on the most used phthalocyanine blue (PB15:1 and PB15:3) and green pigments (PG7), and on the possibility to identify these organic compounds using a methodology like reflectance spectroscopy in the UV, visible and near IR range (UV-vis-NIR RS), performed easily through portable instruments. Laboratory tests and three examples carried out on real paintings are discussed.

  4. Measurement of the enzymes lactate dehydrogenase and creatine kinase using reflectance spectroscopy and reagent strips.

    Science.gov (United States)

    Stevens, J F; Tsang, W; Newall, R G

    1983-01-01

    Two new methods for the assay of total activities of lactate dehydrogenase and creatine kinase are described, in which the enzyme activities are measured from a solid-state reagent strip during a kinetic reaction, the reaction being monitored in the ultra-violet region of the spectrum by reflectance spectroscopy. The performances of these methods are evaluated, and compared to conventional "wet" chemistry methods. The solid-phase reagent methods demonstrated precision and accuracy acceptable for diagnostic purposes, and were easy to use by trained operators. PMID:6655069

  5. The Bone Black Pigment Identification by Noninvasive, In Situ Infrared Reflection Spectroscopy

    Directory of Open Access Journals (Sweden)

    Alessia Daveri

    2018-01-01

    Full Text Available Two real case studies, an oil painting on woven paper and a cycle of mural paintings, have been presented to validate the use of infrared reflection spectroscopy as suitable technique for the identification of bone black pigment. By the use of the sharp weak band at 2013 cm−1, it has been possible to distinguish animal carbon-based blacks by a noninvasive method. Finally, an attempt for an eventual assignment for the widely used sharp band at 2013 cm−1 is discussed.

  6. Investigation of Terra Cotta artefacts with terahertz

    Science.gov (United States)

    Labaune, Julien; Jackson, J. Bianca; Fukunaga, Kaori; White, Jeffrey; D'Alessandro, Laura; Whyte, Alison; Menu, Michel; Mourou, Gerard

    2011-10-01

    Terahertz Time Domain Imaging has been used in the last few years for the investigation of cultural heritage. In this article, the authors demonstrate the possibility to apply it for the investigation of clay artifacts. Tomographic images were obtained of a model in reflection, and an Egyptian vessel in transmission.

  7. Reflectance spectroscopy of PMMA implanted with 50 keV silicon ions

    Energy Technology Data Exchange (ETDEWEB)

    Florian, Bojana [Bulgarian Institute of Metrology, 2 Prof. P. Mutafchiev Str., 1797 Sofia (Bulgaria); Stefanov, Ivan [Department of Quantum Electronics, Faculty of Physics, Sofia University, 5 James Bourchier Blvd., 1164 Sofia (Bulgaria); Hadjichristov, Georgi [Institute of Solid State Physics, 72 Tzarigradsko Chaussee Blvd., 1784 Sofia (Bulgaria)

    2009-07-01

    Recently, the modification of the specular reflectivity of PMMA implanted with low-energy (50 keV) silicon ions was studied and nano-clusters formed in PMMA by Si{sup +} implantation were evidenced by Raman spectroscopy and electrical measurements. Further, the optical loss due to off-specular (diffuse) reflectivity of this ion-implanted polymer is also of practical interest for applications such as micro-optical lenses, diffraction gratings, Fresnel lenses, waveguides, etc. We examined both specular and diffuse reflectivity of Si{sup +} implanted PMMA in the UV-Vis-NIR. The effect from Si{sup +} implantation in the dose range 10{sup 14}-10{sup 17} ions/cm{sup 2} is linked to the structure formed in PMMA where the buried ion-implanted layer has a thickness up to 100 nm. As compared to the pristine PMMA, an enhancement of the reflectivity of Si{sup +} implanted PMMA is observed, that is attributed to the modification of the subsurface region of PMMA upon the ion implantation.

  8. Measurement of the band gap by reflection electron energy loss spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Vos, Maarten, E-mail: maarten.vos@anu.edu.au [Electronic Materials Engineering Department, Research School of Physics and Engineering, The Australian National University, Canberra 0200 (Australia); King, Sean W. [Logic Technology Development, Intel Corporation, Hillsboro, OR 97124 (United States); French, Benjamin L. [Ocotillo Materials Laboratory, Intel Corporation, Chandler, AZ 85248 (United States)

    2016-10-15

    Highlights: • Semiconductors are measured (without surface preparation) using REELS. • At low beam energies it is difficult to measure band gap due to surface impurities. • At very high energies it is difficult to measure band gap due to recoil effect. • At intermediate energies (around 5 keV) one obtains a good estimate of the band gap. - Abstract: We investigate the possibilities of measuring the band gap of a variety of semiconductors and insulators by reflection electron energy loss spectroscopy without additional surface preparation. The band gap is a bulk property, whereas reflection energy loss spectroscopy is generally considered a surface sensitive technique. By changing the energy of the incoming electrons, the degree of surface sensitivity can be varied. Here, we present case studies to determine the optimum condition for the determination of the band gap. At very large incoming electron energies recoil effects interfere with the band gap determination, whereas at very low energies surface effects are obscuring the band gap without surface preparation. Using an incoming energy of 5 keV a reasonable estimate of the band gap is obtained in most cases.

  9. Determination of soil content in chlordecone (organochlorine pesticide) using near infrared reflectance spectroscopy (NIRS)

    Energy Technology Data Exchange (ETDEWEB)

    Brunet, Didier, E-mail: didier.brunet@ird.f [IRD - Institut de Recherche pour le Developpement, UMR Eco and Sols (Ecologie Fonctionnelle et Biogeochimie des Sols), Montpellier SupAgro, Batiment 12, 2 place Viala, 34060 Montpellier Cedex 1 (France); Woignier, Thierry [IRD, UMR Eco and Sols, PRAM (Pole de Recherche Agronomique de la Martinique), BP 213, Petit Morne, 97232 Le Lamentin, Martinique (French West Indies) (France); CNRS - Centre National de la Recherche Scientifique, Universite Montpellier 2, place Eugene Bataillon, 34095 Montpellier Cedex 5 (France); Lesueur-Jannoyer, Magalie; Achard, Raphael [CIRAD (Centre de Cooperation Internationale en Recherche Agronomique pour le Developpement), PRAM, BP 213, Petit Morne, 97232 Le Lamentin, Martinique (French West Indies) (France); Rangon, Luc [IRD, UMR Eco and Sols, PRAM (Pole de Recherche Agronomique de la Martinique), BP 213, Petit Morne, 97232 Le Lamentin, Martinique (French West Indies) (France); Barthes, Bernard G. [IRD - Institut de Recherche pour le Developpement, UMR Eco and Sols (Ecologie Fonctionnelle et Biogeochimie des Sols), Montpellier SupAgro, Batiment 12, 2 place Viala, 34060 Montpellier Cedex 1 (France)

    2009-11-15

    Chlordecone is a toxic organochlorine insecticide that was used in banana plantations until 1993 in the French West Indies. This study aimed at assessing the potential of near infrared reflectance spectroscopy (NIRS) for determining chlordecone content in Andosols, Nitisols and Ferralsols from Martinique. Using partial least square regression, chlordecone content conventionally determined through gas chromatography-mass spectrometry could be correctly predicted by NIRS (Q{sup 2} = 0.75, R{sup 2} = 0.82 for the total set), especially for samples with chlordecone content <12 mg kg{sup -1} or when the sample set was rather homogeneous (Q{sup 2} = 0.91, R{sup 2} = 0.82 for the Andosols). Conventional measures and NIRS predictions were poorly correlated for chlordecone content >12 mg kg{sup -1}, nevertheless ca. 80% samples were correctly predicted when the set was divided into three or four classes of chlordecone content. Thus NIRS could be considered a time- and cost-effective method for characterising soil contamination by chlordecone. - Soil content in chlordecone, an organochlorine insecticide, can be determined time- and cost-effectively using near infrared reflectance spectroscopy (NIRS).

  10. UV-Vis reflection spectroscopy under variable angle incidence at the air-liquid interface.

    Science.gov (United States)

    Roldán-Carmona, Cristina; Rubia-Payá, Carlos; Pérez-Morales, Marta; Martín-Romero, María T; Giner-Casares, Juan J; Camacho, Luis

    2014-03-07

    The UV-Vis reflection spectroscopy (UV-Vis-RS) in situ at the air-liquid interface provides information about tilt and aggregation of chromophores in Langmuir monolayers. This information is particularly important given in most cases the chromophore is located at the polar region of the Langmuir monolayer. This region of the Langmuir monolayers has been hardly accessible by other experimental techniques. In spite of its enormous potential, the application of UV-Vis-RS has been limited mainly to reflection measurements under light normal incidence or at lower incidence angles than the Brewster angle. Remarkably, this technique is quite sensitive to the tilt of the chromophores at values of incidence angles close to or larger than the Brewster angle. Therefore, a novel method to obtain the order parameter of the chromophores at the air-liquid interface by using s- and p-polarized radiation at different incidence angles is proposed. This method allowed for the first time the experimental observation of the two components with different polarization properties of a single UV-Vis band at the air-liquid interface. The method of UV-Vis spectroscopy under variable angle incidence is presented as a new tool for obtaining rich detailed information on Langmuir monolayers.

  11. Determination of soil content in chlordecone (organochlorine pesticide) using near infrared reflectance spectroscopy (NIRS)

    International Nuclear Information System (INIS)

    Brunet, Didier; Woignier, Thierry; Lesueur-Jannoyer, Magalie; Achard, Raphael; Rangon, Luc; Barthes, Bernard G.

    2009-01-01

    Chlordecone is a toxic organochlorine insecticide that was used in banana plantations until 1993 in the French West Indies. This study aimed at assessing the potential of near infrared reflectance spectroscopy (NIRS) for determining chlordecone content in Andosols, Nitisols and Ferralsols from Martinique. Using partial least square regression, chlordecone content conventionally determined through gas chromatography-mass spectrometry could be correctly predicted by NIRS (Q 2 = 0.75, R 2 = 0.82 for the total set), especially for samples with chlordecone content -1 or when the sample set was rather homogeneous (Q 2 = 0.91, R 2 = 0.82 for the Andosols). Conventional measures and NIRS predictions were poorly correlated for chlordecone content >12 mg kg -1 , nevertheless ca. 80% samples were correctly predicted when the set was divided into three or four classes of chlordecone content. Thus NIRS could be considered a time- and cost-effective method for characterising soil contamination by chlordecone. - Soil content in chlordecone, an organochlorine insecticide, can be determined time- and cost-effectively using near infrared reflectance spectroscopy (NIRS).

  12. FORS, Fiber Optics Reflectance Spectroscopy con gli spettrometri miniaturizzati per l’identificazione dei pigmenti

    Directory of Open Access Journals (Sweden)

    Antonino Cosentino

    2014-01-01

    Full Text Available AbstractQuesto articolo riporta i risultati del test di un sistema FORS (Fiber Optics Reflectance Spectroscopy assemblato con componenti Ocean Optics. Questa ditta ha sviluppato una linea di spettrometri miniaturizzati e dal costo estremamente contenuto. Le trascurabili dimensioni e peso di questo sistema FORS lo rendono uno strumento assolutamente adatto alle indagini dell’arte in cantiere. Sono stati testati 54 pigmenti storici in polvere e stesi con gomma arabica, tempera all’uovo, olio e affresco. Il sistema è stato provato su un quadro dell’800 e su opere murali del barocco siciliano.   This paper shows the results of the testing of a FORS (Fiber Optics Reflectance Spectroscopy system assembled with Ocean Optics components and featuring a USB4000 miniaturized and low cost spectrometer. The small dimensions and little weight of this FORS system make it adapt for the specific needs of art examination in the field. 54 historical pigments have been tested both in powder and laid with gum Arabic, egg tempera, linseed oil and fresco. The FORS system was also tested on a 1800s oil painting and on 1700s Sicilian baroque murals and the results compared with multispectral imaging analysis.   

  13. Portable laser-induced breakdown spectroscopy/diffuse reflectance hybrid spectrometer for analysis of inorganic pigments

    Science.gov (United States)

    Siozos, Panagiotis; Philippidis, Aggelos; Anglos, Demetrios

    2017-11-01

    A novel, portable spectrometer, combining two analytical techniques, laser-induced breakdown spectroscopy (LIBS) and diffuse reflectance spectroscopy, was developed with the aim to provide an enhanced instrumental and methodological approach with regard to the analysis of pigments in objects of cultural heritage. Technical details about the hybrid spectrometer and its operation are presented and examples are given relevant to the analysis of paint materials. Both LIBS and diffuse reflectance spectra in the visible and part of the near infrared, corresponding to several neat mineral pigment samples, were recorded and the complementary information was used to effectively distinguish different types of pigments even if they had similar colour or elemental composition. The spectrometer was also employed in the analysis of different paints on the surface of an ancient pottery sherd demonstrating the capabilities of the proposed hybrid diagnostic approach. Despite its instrumental simplicity and compact size, the spectrometer is capable of supporting analytical campaigns relevant to archaeological, historical or art historical investigations, particularly when quick data acquisition is required in the context of surveys of large numbers of objects and samples.

  14. Measurement of the band gap by reflection electron energy loss spectroscopy

    International Nuclear Information System (INIS)

    Vos, Maarten; King, Sean W.; French, Benjamin L.

    2016-01-01

    Highlights: • Semiconductors are measured (without surface preparation) using REELS. • At low beam energies it is difficult to measure band gap due to surface impurities. • At very high energies it is difficult to measure band gap due to recoil effect. • At intermediate energies (around 5 keV) one obtains a good estimate of the band gap. - Abstract: We investigate the possibilities of measuring the band gap of a variety of semiconductors and insulators by reflection electron energy loss spectroscopy without additional surface preparation. The band gap is a bulk property, whereas reflection energy loss spectroscopy is generally considered a surface sensitive technique. By changing the energy of the incoming electrons, the degree of surface sensitivity can be varied. Here, we present case studies to determine the optimum condition for the determination of the band gap. At very large incoming electron energies recoil effects interfere with the band gap determination, whereas at very low energies surface effects are obscuring the band gap without surface preparation. Using an incoming energy of 5 keV a reasonable estimate of the band gap is obtained in most cases.

  15. The use of UV-visible reflectance spectroscopy as an objective tool to evaluate pearl quality.

    Science.gov (United States)

    Agatonovic-Kustrin, Snezana; Morton, David W

    2012-07-01

    Assessing the quality of pearls involves the use of various tools and methods, which are mainly visual and often quite subjective. Pearls are normally classified by origin and are then graded by luster, nacre thickness, surface quality, size, color and shape. The aim of this study was to investigate the capacity of Artificial Neural Networks (ANNs) to classify and estimate the quality of 27 different pearls from their UV-Visible spectra. Due to the opaque nature of pearls, spectroscopy measurements were performed using the Diffuse Reflectance UV-Visible spectroscopy technique. The spectra were acquired at two different locations on each pearl sample in order to assess surface homogeneity. The spectral data (inputs) were smoothed to reduce the noise, fed into ANNs and correlated to the pearl's quality/grading criteria (outputs). The developed ANNs were successful in predicting pearl type, mollusk growing species, possible luster and color enhancing, donor condition/type, recipient/host color, donor color, pearl luster, pearl color, origin. The results of this study shows that the developed UV-Vis spectroscopy-ANN method could be used as a more objective method of assessing pearl quality (grading) and may become a valuable tool for the pearl grading industry.

  16. Ultrafast release and capture of carriers in InGaAs/GaAs quantum dots observed by time-resolved terahertz spectroscopy

    DEFF Research Database (Denmark)

    Porte, Henrik; Jepsen, Peter Uhd; Daghestani, N.

    2009-01-01

    We observe ultrafast release and capture of charge carriers in InGaAs/GaAs quantum dots in a room-temperature optical pump-terahertz probe experiment sensitive to the population dynamics of conducting states. In case of resonant excitation of the quantum dot ground state, the maximum conductivity...... is achieved at approximately 35 ps after photoexcitation, which is assigned to release of carriers from the quantum dots. When exciting carriers into the conduction band of the barriers, depletion of the conductivity via carrier capture into the quantum dots with a few picosecond pump fluence-dependent time...

  17. CO Adsorption and Oxidation at the Catalyst-Water Interface: An Investigation by Attenuated Total Reflection Infrared Spectroscopy.

    NARCIS (Netherlands)

    Ebbesen, S.D.; Mojet, Barbara; Lefferts, Leonardus

    2006-01-01

    Adsorption of carbon monoxide and oxidation of preadsorbed carbon monoxide from gas and aqueous phases were studied on a platinum catalyst deposited on a ZnSe internal reflection element (IRE) using attenuated total reflection infrared (ATR-IR) spectroscopy. The results of this study convincingly

  18. On the prediction of threshold friction velocity of wind erosion using soil reflectance spectroscopy

    Science.gov (United States)

    Li, Junran; Flagg, Cody B.; Okin, Gregory S.; Painter, Thomas H.; Dintwe, Kebonye; Belnap, Jayne

    2015-01-01

    Current approaches to estimate threshold friction velocity (TFV) of soil particle movement, including both experimental and empirical methods, suffer from various disadvantages, and they are particularly not effective to estimate TFVs at regional to global scales. Reflectance spectroscopy has been widely used to obtain TFV-related soil properties (e.g., moisture, texture, crust, etc.), however, no studies have attempted to directly relate soil TFV to their spectral reflectance. The objective of this study was to investigate the relationship between soil TFV and soil reflectance in the visible and near infrared (VIS–NIR, 350–2500 nm) spectral region, and to identify the best range of wavelengths or combinations of wavelengths to predict TFV. Threshold friction velocity of 31 soils, along with their reflectance spectra and texture were measured in the Mojave Desert, California and Moab, Utah. A correlation analysis between TFV and soil reflectance identified a number of isolated, narrow spectral domains that largely fell into two spectral regions, the VIS area (400–700 nm) and the short-wavelength infrared (SWIR) area (1100–2500 nm). A partial least squares regression analysis (PLSR) confirmed the significant bands that were identified by correlation analysis. The PLSR further identified the strong relationship between the first-difference transformation and TFV at several narrow regions around 1400, 1900, and 2200 nm. The use of PLSR allowed us to identify a total of 17 key wavelengths in the investigated spectrum range, which may be used as the optimal spectral settings for estimating TFV in the laboratory and field, or mapping of TFV using airborne/satellite sensors.

  19. External amplitude and frequency modulation of a terahertz quantum cascade laser using metamaterial/graphene devices.

    Science.gov (United States)

    Kindness, S J; Jessop, D S; Wei, B; Wallis, R; Kamboj, V S; Xiao, L; Ren, Y; Braeuninger-Weimer, P; Aria, A I; Hofmann, S; Beere, H E; Ritchie, D A; Degl'Innocenti, R

    2017-08-09

    Active control of the amplitude and frequency of terahertz sources is an essential prerequisite for exploiting a myriad of terahertz applications in imaging, spectroscopy, and communications. Here we present a optoelectronic, external modulation technique applied to a terahertz quantum cascade laser which holds the promise of addressing a number of important challenges in this research area. A hybrid metamaterial/graphene device is implemented into an external cavity set-up allowing for optoelectronic tuning of feedback into a quantum cascade laser. We demonstrate powerful, all-electronic, control over the amplitude and frequency of the laser output. Full laser switching is performed by electrostatic gating of the metamaterial/graphene device, demonstrating a modulation depth of 100%. External control of the emission spectrum is also achieved, highlighting the flexibility of this feedback method. By taking advantage of the frequency dispersive reflectivity of the metamaterial array, different modes of the QCL output are selectively suppressed using lithographic tuning and single mode operation of the multi-mode laser is enforced. Side mode suppression is electrically modulated from ~6 dB to ~21 dB, demonstrating active, optoelectronic modulation of the laser frequency content between multi-mode and single mode operation.

  20. Aspheric lenses for terahertz imaging.

    Science.gov (United States)

    Lo, Yat Hei; Leonhardt, Rainer

    2008-09-29

    We present novel designs for aspheric lenses used in terahertz (THz) imaging. As different surfaces result in different beam shaping properties and in different losses from reflection and absorption, the resultant imaging resolution (i.e. the focal spot size) depends critically on the design approach. We evaluate the different lens designs using Kirchhoff's scalar diffraction theory, and test the predictions experimentally. We also show that our lenses can achieve sub-wavelength resolution. While our lens designs are tested with THz radiation, the design considerations are applicable also to other regions of the electro-magnetic spectrum.

  1. Monitoring the in-situ oxide growth on uranium by ultraviolet-visible reflectance spectroscopy

    Science.gov (United States)

    Schweke, Danielle; Maimon, Chen; Chernia, Zelig; Livneh, Tsachi

    2012-11-01

    We demonstrate the in-situ monitoring of oxide growth on U-0.1 wt. % Cr by means of UV-visible reflectance spectroscopy in the thickness range of ˜20-150 nm. Two different approaches are presented: In the "modeling approach," we employ a model for a metallic substrate covered by a dielectric layer, while taking into account the buildup of oxygen gradient and surface roughness. Then, we fit the simulated spectra to the experimental one. In the "extrema analysis," we derive an approximated analytical expression, which relates the oxide thickness to the position of the extrema in the reflectance spectra based on the condition for optical interference of the reflected light. Good agreement is found between the values extracted by the two procedures. Activation energy of ˜21 kcal/mole was obtained by monitoring the oxide growth in the temperature range of 22-90 °C. The upper bound for the thickness determination is argued to be mostly dictated by cracking and detachment processes in the formed oxide.

  2. Identification of cattle, llama and horse meat by near infrared reflectance or transflectance spectroscopy.

    Science.gov (United States)

    Mamani-Linares, L W; Gallo, C; Alomar, D

    2012-02-01

    Visible and near infrared reflectance spectroscopy (VIS-NIRS) was used to discriminate meat and meat juices from three livestock species. In a first trial, samples of Longissimus lumborum muscle, corresponding to beef (31) llamas (21) and horses (27), were homogenised and their spectra collected in reflectance (NIRSystems 6500 scanning monochromator, in the range of 400-2500 nm). In the second trial, samples of meat juice (same muscle) from the same species (20 beef, 19 llama and 19 horse) were scanned in folded transmission (transflectance). Discriminating models (PLS regression) were developed against "dummy" variables, testing different mathematical treatments of the spectra. Best models indentified the species of almost all samples by their meat (reflectance) or meat juice (transflectance) spectra. A few (three of beef and one of llama, for meat samples; one of beef and one of horse, for juice samples) were classified as uncertain. It is concluded that NIRS is an effective tool to recognise meat and meat juice from beef, llama and horses. Copyright © 2011 Elsevier Ltd. All rights reserved.

  3. Identification of natural red and purple dyes on textiles by Fiber-optics Reflectance Spectroscopy.

    Science.gov (United States)

    Maynez-Rojas, M A; Casanova-González, E; Ruvalcaba-Sil, J L

    2017-05-05

    Understanding dye chemistry and dye processes is an important issue for studies of cultural heritage collections and science conservation. Fiber Optics Reflectance Spectroscopy (FORS) is a powerful technique, which allows preliminary dye identification, causing no damage or mechanical stress on the artworks subjected to analysis. Some information related to specific light scattering and absorption can be obtained in the UV-visible and infrared range (300-1400nm) and it is possible to discriminate the kind of support fiber in the near infrared region (1000-2500nm). The main spectral features of natural dye fibers samples, such as reflection maxima, inflection points and reflection minima, can be used in the differentiation of various red natural dyes. In this work, a set of dyed references were manufactured following Mexican recipes with red dyes (cochineal and brazilwood) in order to determine the characteristic FORS spectral features of fresh and aged dyed fibers for their identification in historical pieces. Based on these results, twenty-nine indigenous textiles belonging to the National Commission for the Development of Indigenous People of Mexico were studied. Cochineal and brazilwood were successfully identified by FORS in several pieces, as well as the mixture of cochineal and indigo for purple color. Copyright © 2017 Elsevier B.V. All rights reserved.

  4. Optically pumped terahertz sources

    Institute of Scientific and Technical Information of China (English)

    ZHONG Kai; SHI Wei; XU DeGang; LIU PengXiang; WANG YuYe; MEI JiaLin; YAN Chao; FU ShiJie; YAO JianQuan

    2017-01-01

    High-power terahertz (THz) generation in the frequency range of0.1-10 THz has been a fast-developing research area ever since the beginning of the THz boom two decades ago,enabling new technological breakthroughs in spectroscopy,communication,imaging,etc.By using optical (laser) pumping methods with near-or mid-infrared (IR) lasers,flexible and practical THz sources covering the whole THz range can be realized to overcome the shortage of electronic THz sources and now they are playing important roles in THz science and technology.This paper overviews various optically pumped THz sources,including femtosecond laser based ultrafast broadband THz generation,monochromatic widely tunable THz generation,single-mode on-chip THz source from photomixing,and the traditional powerful THz gas lasers.Full descriptions from basic principles to the latest progress are presented and their advantages and disadvantages are discussed as well.It is expected that this review gives a comprehensive reference to researchers in this area and additionally helps newcomers to quickly gain understanding of optically pumped THz sources.

  5. Graphene-based magnetless converter of terahertz wave polarization

    Science.gov (United States)

    Melnikova, Veronica S.; Polischuk, Olga V.; Popov, Vyacheslav V.

    2016-04-01

    The polarization conversion of terahertz radiation by the periodic array of graphene nanoribbons located at the surface of a high-refractive-index dielectric substrate (terahertz prism) is studied theoretically. Giant polarization conversion at the plasmon resonance frequencies takes place without applying external DC magnetic field. It is shown that the total polarization conversion can be reached at the total internal reflection of THz wave from the periodic array of graphene nanoribbons even at room temperature.

  6. Far-infrared reflection-absorption spectroscopy of amorphous and polycrystalline gallium arsenide films

    International Nuclear Information System (INIS)

    Gregory, J.R.

    1992-01-01

    We have reported far-infrared reflection absorption spectra (30-320CM -1 ) at 30 and 310K for nine films of non-stoichiometric GaAs. The FIRRAS measurements were performed using the grazing incidence FIR double-modulation spectroscopy technique first described by DaCosta and Coleman. The films were fabricated by molecular beam deposition on metallized substrates for two As/Ga molecular beam flux ratios. The films were characterized by depth profilometry, IRAS, XRD, and x-ray microprobe analysis. Film thicknesses ranged from 800 to 5800 angstrom and compositions were 45-50% As for a MB flux ratio of 0.29 and 60-70% As for a ratio of 1.12. FIRRAS measurements were made and characterizations performed for as-deposited films and for 5 hour anneals at 473, 573, 673 and 723 degrees C. Vibrational spectra of the crystallized films were interpreted in terms of the exact reflectivity of a thin dielectric film on a conducting substrate, using a classical Lorentzian dielectric function for the response of the film. Resonances appearing in the open-quote forbidden close-quote region between the TO and LO frequencies were modelled with an effective medium approximation and are interpreted as arising from small-scale surface roughness. The behavior of the amorphous film spectra were examined within two models. The effective force constant model describes the variation of the reflection-absorption maxima with measured crystallite size in terms of the effective vibration frequency of 1-D atomic chains having force constants distributed according to the parameters of the crystalline-to-amorphous relaxation length and the crystalline to amorphous force constant ratio. The dielectric function continuum model uses the relaxation of the crystal momentum selection rule to calculate the reflection-absorption spectrum based on a dielectric function in which the oscillator strength is the normalized product of a constant dipole strength and the smoothed vibrational density of states

  7. Imaging with terahertz radiation

    Energy Technology Data Exchange (ETDEWEB)

    Chan, W L; Deibel, Jason; Mittleman, Daniel M [Department of Electrical and Computer Engineering, MS-366, Rice University, 6100 Main St., Houston, TX 77005 (United States)

    2007-08-15

    Within the last several years, the field of terahertz science and technology has changed dramatically. Many new advances in the technology for generation, manipulation, and detection of terahertz radiation have revolutionized the field. Much of this interest has been inspired by the promise of valuable new applications for terahertz imaging and sensing. Among a long list of proposed uses, one finds compelling needs such as security screening and quality control, as well as whimsical notions such as counting the almonds in a bar of chocolate. This list has grown in parallel with the development of new technologies and new paradigms for imaging and sensing. Many of these proposed applications exploit the unique capabilities of terahertz radiation to penetrate common packaging materials and provide spectroscopic information about the materials within. Several of the techniques used for terahertz imaging have been borrowed from other, more well established fields such as x-ray computed tomography and synthetic aperture radar. Others have been developed exclusively for the terahertz field, and have no analogies in other portions of the spectrum. This review provides a comprehensive description of the various techniques which have been employed for terahertz image formation, as well as discussing numerous examples which illustrate the many exciting potential uses for these emerging technologies.

  8. Imaging with terahertz radiation

    International Nuclear Information System (INIS)

    Chan, W L; Deibel, Jason; Mittleman, Daniel M

    2007-01-01

    Within the last several years, the field of terahertz science and technology has changed dramatically. Many new advances in the technology for generation, manipulation, and detection of terahertz radiation have revolutionized the field. Much of this interest has been inspired by the promise of valuable new applications for terahertz imaging and sensing. Among a long list of proposed uses, one finds compelling needs such as security screening and quality control, as well as whimsical notions such as counting the almonds in a bar of chocolate. This list has grown in parallel with the development of new technologies and new paradigms for imaging and sensing. Many of these proposed applications exploit the unique capabilities of terahertz radiation to penetrate common packaging materials and provide spectroscopic information about the materials within. Several of the techniques used for terahertz imaging have been borrowed from other, more well established fields such as x-ray computed tomography and synthetic aperture radar. Others have been developed exclusively for the terahertz field, and have no analogies in other portions of the spectrum. This review provides a comprehensive description of the various techniques which have been employed for terahertz image formation, as well as discussing numerous examples which illustrate the many exciting potential uses for these emerging technologies

  9. Evaluation of apparent viscosity of Para rubber latex by diffuse reflection near-infrared spectroscopy.

    Science.gov (United States)

    Sirisomboon, Panmanas; Chowbankrang, Rawiphan; Williams, Phil

    2012-05-01

    Near-infrared spectroscopy in diffuse reflection mode was used to evaluate the apparent viscosity of Para rubber field latex and concentrated latex over the wavelength range of 1100 to 2500 nm, using partial least square regression (PLSR). The model with ten principal components (PCs) developed using the raw spectra accurately predicted the apparent viscosity with correlation coefficient (r), standard error of prediction (SEP), and bias of 0.974, 8.6 cP, and -0.4 cP, respectively. The ratio of the SEP to the standard deviation (RPD) and the ratio of the SEP to the range (RER) for the prediction were 4.4 and 16.7, respectively. Therefore, the model can be used for measurement of the apparent viscosity of field latex and concentrated latex in quality assurance and process control in the factory.

  10. Rapid biochemical methane potential prediction of urban organic waste with near-infrared reflectance spectroscopy

    DEFF Research Database (Denmark)

    Fitamo, Temesgen Mathewos; Triolo, Jin Mi; Boldrin, Alessio

    2017-01-01

    . The aim of the present study is to develop a fast and reliable model based on near-infrared reflectance spectroscopy (NIRS) for the BMP prediction of urban organic waste (UOW). The model comprised 87 UOW samples. Additionally, 88 plant biomass samples were included, to develop a combined model predicting...... BMP. The coefficient of determination (R2) and root mean square error in prediction (RMSEP) of the UOW model were 0.88 and 44 mL CH4/g VS, while the combined model was 0.89 and 50 mL CH4/g VS. Improved model performance was obtained for the two individual models compared to the combined version...

  11. Andreev Reflection Spectroscopy of Nb-doped Bi2Se3 Topological Insulator

    Science.gov (United States)

    Kurter, C.; Finck, A. D. K.; Qiu, Y.; Huemiller, E.; Weis, A.; Atkinson, J.; Medvedeva, J.; Hor, Y. S.; van Harlingen, D. J.

    2015-03-01

    Doped topological insulators are speculated to realize p-wave superconductivity with unusual low energy quasiparticles, such as surface Andreev bound states. We present point contact spectroscopy of thin exfoliated flakes of Nb-doped Bi2Se3 where superconductivity persists up to ~ 1 K, compared to 3.2 K in bulk crystals. The critical magnetic field is strongly anisotropic, consistent with quasi-2D behavior. Andreev reflection measurements of devices with low resistance contacts result in prominent BTK-like behavior with an enhanced conductance plateau at low bias. For high resistance contacts, we observe a split zero bias conductance anomaly and additional features at the superconducting gap. Our results suggest that this material is a promising platform for studying topological superconductivity. We acknowledge support from Microsoft Project Q.

  12. Experimental analysis of bruises in human volunteers using radiometric depth profiling and diffuse reflectance spectroscopy

    Science.gov (United States)

    Vidovič, Luka; Milanič, Matija; Majaron, Boris

    2015-07-01

    We combine pulsed photothermal radiometry (PPTR) depth profiling with diffuse reflectance spectroscopy (DRS) measurements for a comprehensive analysis of bruise evolution in vivo. While PPTR enables extraction of detailed depth distribution and concentration profiles of selected absorbers (e.g. melanin, hemoglobin), DRS provides information in a wide range of visible wavelengths and thus offers an additional insight into dynamics of the hemoglobin degradation products. Combining the two approaches enables us to quantitatively characterize bruise evolution dynamics. Our results indicate temporal variations of the bruise evolution parameters in the course of bruise self-healing process. The obtained parameter values and trends represent a basis for a future development of an objective technique for bruise age determination.

  13. Analysis of hemodynamics in human skin using photothermal radiometry and diffuse reflectance spectroscopy

    Science.gov (United States)

    Verdel, Nina; Marin, Ana; Vidovič, Luka; Milanič, Matija; Majaron, Boris

    2017-07-01

    We present a novel methodology for quantitative analysis of hemodynamics in human skin in vivo. Our approach combines pulsed photothermal radiometry (i.e., time-resolved measurements of midinfrared emission from sample surface after exposure to a short light pulse) and diffuse reflectance spectroscopy in visible part of the spectrum. Experimental data are fitted with predictions of a numerical model of light transport in a four-layer skin model (i.e., inverse Monte Carlo), which allows assessment of the layer thicknesses, chromophore contents (e.g., melanin, oxy- and deoxy-hemoglobin), as well as scattering properties. The performance is tested in comparison analysis of healthy skin before and during application of a blood pressure cuff (at 200 mm Hg) for 5 minutes.

  14. Using reflectance anisotropy spectroscopy to characterize capped silver nanostructures grown on silicon

    Energy Technology Data Exchange (ETDEWEB)

    Fleischer, K.; Jacob, J.; McGilp, J.F. [School of Physics, Trinity College Dublin, Dublin 2 (Ireland); Chandola, S. [School of Physics, Trinity College Dublin, Dublin 2 (Ireland); ISAS - Institute for Analytical Sciences, Department Berlin, Albert-Einstein-Strasse 9, 12489 Berlin (Germany); Esser, N. [ISAS - Institute for Analytical Sciences, Department Berlin, Albert-Einstein-Strasse 9, 12489 Berlin (Germany)

    2008-07-01

    Using the single domain Si(111)-3 x 1-Ag surface as a template, room temperature deposition of two or more monolayers of Ag leads to the formation of metallic nanostructures. Reflectance anisotropy spectroscopy (RAS) in the infrared (IR) spectral region is used to analyse the anisotropic conductivity of the structures. The anisotropy is found to be influenced by the offcut angle of the substrate, and hence the terrace width. The Ag nanostructures were capped with Si to form a near-IR transparent protecting layer. The samples are stable to exposure to ambient conditions for significant periods. The RAS spectra are compared to model calculations, which support the conclusion that the buried metallic Ag nanostructures survive the capping process. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  15. Combining total internal reflection sum frequency spectroscopy spectral imaging and confocal fluorescence microscopy.

    Science.gov (United States)

    Allgeyer, Edward S; Sterling, Sarah M; Gunewardene, Mudalige S; Hess, Samuel T; Neivandt, David J; Mason, Michael D

    2015-01-27

    Understanding surface and interfacial lateral organization in material and biological systems is critical in nearly every field of science. The continued development of tools and techniques viable for elucidation of interfacial and surface information is therefore necessary to address new questions and further current investigations. Sum frequency spectroscopy (SFS) is a label-free, nonlinear optical technique with inherent surface specificity that can yield critical organizational information on interfacial species. Unfortunately, SFS provides no spatial information on a surface; small scale heterogeneities that may exist are averaged over the large areas typically probed. Over the past decade, this has begun to be addressed with the advent of SFS microscopy. Here we detail the construction and function of a total internal reflection (TIR) SFS spectral and confocal fluorescence imaging microscope directly amenable to surface investigations. This instrument combines, for the first time, sample scanning TIR-SFS imaging with confocal fluorescence microscopy.

  16. Compact terahertz spectrometer based on disordered rough surfaces

    Science.gov (United States)

    Yang, Tao; Jiang, Bing; Ge, Jia-cheng; Zhu, Yong-yuan; Li, Xing-ao; Huang, Wei

    2018-01-01

    In this paper, a compact spectrometer based on disordered rough surfaces for operation in the terahertz band is presented. The proposed spectrometer consists of three components, which are used for dispersion, modulation and detection respectively. The disordered rough surfaces, which are acted as the dispersion component, are modulated by the modulation component. Different scattering intensities are captured by the detection component with different extent of modulation. With a calibration measurement process, one can reconstruct the spectra of the probe terahertz beam by solving a system of simultaneous linear equations. A Tikhonov regularization approach has been implemented to improve the accuracy of the spectral reconstruction. The reported broadband, compact, high-resolution terahertz spectrometer is well suited for portable terahertz spectroscopy applications.

  17. Quality Control of Valerianae Radix by Attenuated Total Reflection Fourier Transform Infrared (ATR-FTIR) Spectroscopy.

    Science.gov (United States)

    Nikzad-Langerodi, Ramin; Arth, Katharina; Klatte-Asselmeyer, Valerie; Bressler, Sabine; Saukel, Johannes; Reznicek, Gottfried; Dobeš, Christoph

    2018-04-01

    (Acetoxy-)valerenic acid and total essential oil content are important quality attributes of pharmacy grade valerian root (Valerianae radix). Traditional analysis of these quantities is time-consuming and necessitates (harmful) solvents. Here we investigated an application of attenuated total reflection Fourier transform infrared spectroscopy for extractionless analysis of these quality attributes on a representative sample comprising 260 wild-crafted individuals covering the Central European taxonomic diversity of the Valeriana officinalis L. s. l. species aggregate with its three major ploidy cytotypes (i.e., di-, tetra- and octoploid). Calibration models were built by orthogonal partial least squares regression for quantitative analysis of (acetoxy-)valerenic acid and total essential oil content. For the latter, we propose a simplistic protocol involving apolar extraction followed by gas chromatography as a reference method for multivariate calibration in order to handle the analysis of samples taken from individual plants. We found good predictive ability of chemometric models for quantification of valerenic acid, acetoxyvalerenic acid, total sesquiterpenoid acid, and essential oil content with a root mean squared error of cross-validation of 0.064, 0.043, and 0.09 and root mean squared error of prediction of 0.066, 0.057, and 0.09 (% content), respectively. Orthogonal partial least squares discriminant analysis revealed good discriminability between the most productive phenotype (i.e., the octoploid cytotype) in terms of sesquiterpenoid acids, and the less productive ones (i.e., di- and tetraploid). All in all, our results demonstrate the application of attenuated total reflection Fourier transform infrared spectroscopy for rapid, extractionless estimation of the most important quality attributes of valerian root and minimally invasive identification of the most productive phenotype in terms of sesquiterpenoid acids. Georg Thieme Verlag KG Stuttgart · New

  18. The role of total-reflection x-ray fluorescence in atomic spectroscopy

    International Nuclear Information System (INIS)

    Toelg, G.; Klockenkaemper, R.

    1993-01-01

    Total-reflection X-ray fluorescence (TXRF) is a universal and economic method for the simultaneous determination of elements with atomic numbers > 11 down to the lower pg-level. It is a microanalytical tool for the analysis of small sample amounts placed on flat carriers and for contaminations on flat sample surfaces. Analyses of stratified near-surface layers are made possible by varying the incident angle of the primary beam in the region of total-reflection. This non-destructive method is especially suitable for thin layers of a few nanometres, deposited on wafer material although not usable as a microprobe method with a high lateral resolution. Furthermore, depth profiles of biological samples can be recorded by means of microtome sectioning of only a few micrometres, as, for example in the gradient analysis of human organs. In addition to micro- and surface-layer analysis, TXRF is effectively applied to element trace analysis. Homogeneous solutions, for example aqueous solutions, high-purity acids or body fluids, are pipetted onto carriers and, after evaporation, the dry residues are analyzed directly down to the pg/ml region. Particularly advantageous is the absence of matrix effects, so that an easy calibration can be carried out by adding a single internal standard element. A digestion or separation step preceding the actual determination becomes necessary if a more complex matrix is to be analysed or especially low detection limits have to be reached. A critical evaluation of the recent developments in atomic spectroscopy places TXRF in a leading position. Its outstanding features compete with those of e.g. electrothermal atomic absorption spectrometry (ETAAS), microwave induced plasma optical emission spectroscopy (MIP-OES) and inductively coupled plasma mass spectrometry (ICP-MS) in the field of micro- and trace analysis and with Rutherford backscattering (RBS) and secondary ion mass spectrometry (SIMS) in the surface-layer analysis. (author)

  19. Ultrafast Terahertz Conductivity of Photoexcited Nanocrystalline Silicon

    DEFF Research Database (Denmark)

    Cooke, David; MacDonald, A. Nicole; Hryciw, Aaron

    2007-01-01

    The ultrafast transient ac conductivity of nanocrystalline silicon films is investigated using time-resolved terahertz spectroscopy. While epitaxial silicon on sapphire exhibits a free carrier Drude response, silicon nanocrystals embedded in glass show a response that is best described by a class...... in the silicon nanocrystal films is dominated by trapping at the Si/SiO2 interface states, occurring on a 1–100 ps time scale depending on particle size and hydrogen passivation......The ultrafast transient ac conductivity of nanocrystalline silicon films is investigated using time-resolved terahertz spectroscopy. While epitaxial silicon on sapphire exhibits a free carrier Drude response, silicon nanocrystals embedded in glass show a response that is best described...

  20. Polarization-sensitive electro-optic detection of terahertz wave using three different types of crystal symmetry: Toward broadband polarization spectroscopy

    International Nuclear Information System (INIS)

    Oguchi, Kenichi; Iwasaki, Hotsumi; Okano, Makoto; Watanabe, Shinichi

    2016-01-01

    We investigated polarization-sensitive electro-optic (EO) detection of terahertz (THz) waves by using two uniaxial crystals: a c-cut gallium selenide and a c-cut lithium niobate crystals. We formulated a general frequency-domain description of EO detection by in-plane isotropic EO crystals, which holds regardless of the frequency. Based on this description, the polarization of THz waves can be derived by analyzing EO sampling signals measured with two orthogonal configurations of the in-plane isotropic EO crystals as well as typical (111) zinc-blende EO crystals. In addition, we experimentally demonstrated that the frequency-dependent polarization of THz waves can be reproducibly retrieved using three EO crystals with different crystal symmetries and with different phase matching conditions. Our description provides essential information for practical polarization sensing in the THz frequency range as well as in the mid-infrared range

  1. Terahertz spectroscopic investigation of Chinese herbal medicine

    Energy Technology Data Exchange (ETDEWEB)

    Zhao Xiaoli; Li Jiusheng, E-mail: forever-li@126.com [Centre for THz Research, China Jiliang University, Hangzhou 310018 (China)

    2011-02-01

    The absorption spectra of panax notoginseng and glycyrrhiza in the frequency range of 0.2{approx}1.6THz has been measured with terahertz time-domin spectroscopy at room temperature. Simultaneously, the corresponding theoretical spectra were given by using density functional theory methods. It was found that the absorption peaks of the two molecules obtained by theoretical were in good agreement with the experimental results.

  2. Terahertz spectroscopic investigation of Chinese herbal medicine

    Science.gov (United States)

    Xiao-li, Zhao; Jiu-sheng, Li

    2011-02-01

    The absorption spectra of panax notoginseng and glycyrrhiza in the frequency range of 0.2~1.6THz has been measured with terahertz time-domin spectroscopy at room temperature. Simultaneously, the corresponding theoretical spectra were given by using density functional theory methods. It was found that the absorption peaks of the two molecules obtained by theoretical were in good agreement with the experimental results.

  3. Monitoring of caffeine consumption effect on skin blood properties by diffuse reflectance spectroscopy

    Science.gov (United States)

    Milanic, Matija; Marin, Ana; Stergar, Jost; Verdel, Nina; Majaron, Boris

    2017-07-01

    Caffeine is the most widely consumed psychoactive substance in the world. It affects many tissues and organs, in particular central nervous system, heart, and blood vessels. The effect of caffeine on vascular smooth muscle cells is an initial transient contraction followed by significant vasodilatation. In this study we investigate the use of diffuse reflectance spectroscopy (DRS) for monitoring of vascular changes in human skin induced by caffeine consumption. DRS spectra were recorded on volar sides of the forearms of ten healthy volunteers at time delays of 0, 30, 60, 120, and 180 minutes after consumption of caffeine, while one subject served as a negative control. Analytical diffusion approximation solutions for diffuse reflectance from three-layer structures were used to assess skin composition (e.g., dermal blood volume fraction and oxygen saturation) by fitting to experimental data. The results demonstrate that cutaneous vasodynamics induced by caffeine consumption can be monitored by DRS, while changes in the control subject not consuming caffeine were insignificant.

  4. Quantitative skin color measurements in acanthosis nigricans patients: colorimetry and diffuse reflectance spectroscopy.

    Science.gov (United States)

    Pattamadilok, Bensachee; Devpura, Suneetha; Syed, Zain U; Agbai, Oma N; Vemulapalli, Pranita; Henderson, Marsha; Rehse, Steven J; Mahmoud, Bassel H; Lim, Henry W; Naik, Ratna; Hamzavi, Iltefat H

    2012-08-01

    Tristimulus colorimetry and diffuse reflectance spectroscopy (DRS) are white-light skin reflectance techniques used to measure the intensity of skin pigmentation. The tristimulus colorimeter is an instrument that measures a perceived color and the DRS instrument measures biological chromophores of the skin, including oxy- and deoxyhemoglobin, melanin and scattering. Data gathered from these tools can be used to understand morphological changes induced in skin chromophores due to conditions of the skin or their treatments. The purpose of this study was to evaluate the use of these two instruments in color measurements of acanthosis nigricans (AN) lesions. Eight patients with hyperinsulinemia and clinically diagnosable AN were seen monthly. Skin pigmentation was measured at three sites: the inner forearm, the medial aspect of the posterior neck, and anterior neck unaffected by AN. Of the three, measured tristimulus L*a*b* color parameters, the luminosity parameter L* was found to most reliably distinguish lesion from normally pigmented skin. The DRS instrument was able to characterize a lesion on the basis of the calculated melanin concentration, though melanin is a weak indicator of skin change and not a reliable measure to be used independently. Calculated oxyhemoglobin and deoxyhemoglobin concentrations were not found to be reliable indicators of AN. Tristimulus colorimetry may provide reliable methods for respectively quantifying and characterizing the objective color change in AN, while DRS may be useful in characterizing changes in skin melanin content associated with this skin condition. © 2012 John Wiley & Sons A/S.

  5. Impact of one-layer assumption on diffuse reflectance spectroscopy of skin

    Science.gov (United States)

    Hennessy, Ricky; Markey, Mia K.; Tunnell, James W.

    2015-02-01

    Diffuse reflectance spectroscopy (DRS) can be used to noninvasively measure skin properties. To extract skin properties from DRS spectra, you need a model that relates the reflectance to the tissue properties. Most models are based on the assumption that skin is homogenous. In reality, skin is composed of multiple layers, and the homogeneity assumption can lead to errors. In this study, we analyze the errors caused by the homogeneity assumption. This is accomplished by creating realistic skin spectra using a computational model, then extracting properties from those spectra using a one-layer model. The extracted parameters are then compared to the parameters used to create the modeled spectra. We used a wavelength range of 400 to 750 nm and a source detector separation of 250 μm. Our results show that use of a one-layer skin model causes underestimation of hemoglobin concentration [Hb] and melanin concentration [mel]. Additionally, the magnitude of the error is dependent on epidermal thickness. The one-layer assumption also causes [Hb] and [mel] to be correlated. Oxygen saturation is overestimated when it is below 50% and underestimated when it is above 50%. We also found that the vessel radius factor used to account for pigment packaging is correlated with epidermal thickness.

  6. Pink berry grape (Vitis vinifera L.) characterization: Reflectance spectroscopy, HPLC and molecular markers.

    Science.gov (United States)

    Rustioni, Laura; De Lorenzis, Gabriella; Hârţa, Monica; Failla, Osvaldo

    2016-01-01

    Color has a fundamental role for the qualitative evaluation and cultivar characterization of fruits. In grape, a normally functional pigment biosynthesis leads to the accumulation of a high quantity of anthocyanins. In this work, 28 Vitis vinifera L. cultivars accumulating low anthocyanins in berries were studied to characterize the biosynthetic dysfunctions in both a phenotypic and genotypic point of view. Reflectance spectroscopy, HPLC profiles and molecular markers related to VvMybA1 and VvMybA2 genes allowed a detailed description of the pigment-related characteristics of these cultivars. Data were consistent concerning the heterozygosity of the non-functional allele in both investigated genes, resulting in a low colored phenotype as described by reflectance. However, the variability in berry colour among our samples was not fully explained by MybA locus, probably due to specific interferences among the biosynthetic pathways, as suggested by the anthocyanin profile variations detected among our samples. The results presented in this work confirmed the importance of the genetic background: grapes accumulating high levels of cyanidin-3-O-glucosides (di-substituted anthocyanin) are generally originated by white cultivar retro-mutations and they seem to preserve the anomalies in the flavonoid hydroxylases enzymes which negatively affect the synthesis of tri-substituted anthocyanins. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

  7. Near IR Scanning Angle Total Internal Reflection Raman Spectroscopy at Smooth Gold Films

    Energy Technology Data Exchange (ETDEWEB)

    McKee, Kristopher; Meyer, Matthew; Smith, Emily

    2012-04-13

    Total internal reflection (TIR) Raman and reflectivity spectra were collected for nonresonant analytes as a function of incident angle at sapphire or sapphire/smooth 50 nm gold interfaces using 785 nm excitation. For both interfaces, the Raman signal as a function of incident angle is well-modeled by the calculated interfacial mean square electric field (MSEF) relative to the incident field times the thickness of the layer being probed in the Raman measurement (D{sub RS}). The Raman scatter was reproducibly enhanced at the interface containing a gold film relative to the sapphire interface by a factor of 4.3–4.6 for aqueous pyridine or 2.2–3.7 for neat nitrobenzene, depending on the analyzed vibrational mode. The mechanism for the increased Raman signal is the enhanced MSEF at incident angles where propagating surface plasmons are excited in the metal film. The background from the TIR prism was reduced by 89–95% with the addition of the gold film, and the percent relative uncertainty in peak area was reduced from 15 to 1.7% for the 1347 cm–1 mode of nitrobenzene. Single monolayers of benzenethiol (S/N = 6.8) and 4-mercaptopyridine (S/N = 16.5) on gold films were measured by TIR Raman spectroscopy with 785 nm excitation (210 mW) without resonant enhancement in 1 min.

  8. Spatial Terahertz Modulator

    Science.gov (United States)

    Xie, Zhenwei; Wang, Xinke; Ye, Jiasheng; Feng, Shengfei; Sun, Wenfeng; Akalin, Tahsin; Zhang, Yan

    2013-11-01

    Terahertz (THz) technology is a developing and promising candidate for biological imaging, security inspection and communications, due to the low photon energy, the high transparency and the broad band properties of the THz radiation. However, a major encountered bottleneck is lack of efficient devices to manipulate the THz wave, especially to modulate the THz wave front. A wave front modulator should allow the optical or electrical control of the spatial transmission (or reflection) of an input THz wave and hence the ability to encode the information in a wave front. Here we propose a spatial THz modulator (STM) to dynamically control the THz wave front with photo-generated carriers. A computer generated THz hologram is projected onto a silicon wafer by a conventional spatial light modulator (SLM). The corresponding photo-generated carrier spatial distribution will be induced, which forms an amplitude hologram to modulate the wave front of the input THz beam. Some special intensity patterns and vortex beams are generated by using this method. This all-optical controllable STM is structure free, high resolution and broadband. It is expected to be widely used in future THz imaging and communication systems.

  9. The application of Near Infrared Reflectance Spectroscopy (NIRS) for the quantitative analysis of hydrocortisone in primary materials

    OpenAIRE

    A. PITTAS; C. SERGIDES; K. NIKOLICH

    2001-01-01

    Near Infrared Reflectance Spectroscopy (NIRS), coupled with fiber optic probes, has been shown to be a quick and reliable analytical tool for quality assurance and quality control in the pharmaceutical industry, both for verifications of raw materials and quantification of the active ingredients in final products. In this paper, a typical pharmaceutical product, hydrocortisone sodium succinate, is used as an example for the application of NIR spectroscopy for quality control. In order to deve...

  10. Assessing Salinity in Cotton and Tomato Plants by Using Reflectance Spectroscopy

    Science.gov (United States)

    Goldshleger, Naftaly

    2016-04-01

    Irrigated lands in semi-arid and arid areas are subjected to salinization processes. An example of this phenomenon is the Jezreel Valley in northern Israel where soil salinity has increased over the years. The increase in soil salinity results in the deterioration of the soil structure and crops damage. In this experiment we quantified the relation between the chemical and spectral features of cotton and tomato plants and their mutual relationship to soil salinity. The experiment was carried out as part of ongoing research aiming to detect and monitor saline soils and vegetation by combining different remote sensing methods. The aim of this study was to use vegetation reflectance measurements to predict foliar Cl and Na concentration and assess salinity in the soil and in vegetation by their reflectance measurements. The model developed for determining concentrations of chlorine and sodium in tomato and cotton produced good results ( R2 = 0.92 for sodium and 0.85 for chlorine in tomato and R2 = 0.84 for sodium and 0.82 for chlorine in cotton). Lately, we extend the method to calculate vegetation salinity, by doing correlation between the reflectance slopes of the tested crops CL and Na from two research areas. The developed model produced a good results for all the data (R2=0.74) Our method can be implemented to assess vegetation salinity ahead of planting, and developed as a generic tool for broader use for agriculture in semi-arid regions. In our opinion these results show the possibility of monitoring for a threshold level of salinity in tomato and cotton leaves so remedial action can be taken in time to prevent crop damage. Our results strongly suggest that future imaging spectroscopy remote sensing measurements collected by airborne and satellite platforms could measure the salinity of soil and vegetation over larger areas. These results can be the first steps for generic a model which includes more vegetation for salinity measurements.

  11. Analysis of ecstasy tablets: comparison of reflectance and transmittance near infrared spectroscopy.

    Science.gov (United States)

    Schneider, Ralph Carsten; Kovar, Karl-Artur

    2003-07-08

    Calibration models for the quantitation of commonly used ecstasy substances have been developed using near infrared spectroscopy (NIR) in diffuse reflectance and in transmission mode by applying seized ecstasy tablets for model building and validation. The samples contained amphetamine, N-methyl-3,4-methylenedioxy-amphetamine (MDMA) and N-ethyl-3,4-methylenedioxy-amphetamine (MDE) in different concentrations. All tablets were analyzed using high performance liquid chromatography (HPLC) with diode array detection as reference method. We evaluated the performance of each NIR measurement method with regard to its ability to predict the content of each tablet with a low root mean square error of prediction (RMSEP). Best calibration models could be generated by using NIR measurement in transmittance mode with wavelength selection and 1/x-transformation of the raw data. The models build in reflectance mode showed higher RMSEPs using as data pretreatment, wavelength selection, 1/x-transformation and a second order Savitzky-Golay derivative with five point smoothing was applied to obtain the best models. To estimate the influence of inhomogeneities in the illegal tablets, a calibration of the destroyed, i.e. triturated samples was build and compared to the corresponding data of the whole tablets. The calibrations using these homogenized tablets showed lower RMSEPs. We can conclude that NIR analysis of ecstasy tablets in transmission mode is more suitable than measurement in diffuse reflectance to obtain quantification models for their active ingredients with regard to low errors of prediction. Inhomogeneities in the samples are equalized when measuring the tablets as powdered samples.

  12. Reflectance-difference spectroscopy as an optical probe for in situ determination of doping levels in GaAs

    Energy Technology Data Exchange (ETDEWEB)

    Lastras-Martinez, A.; Lara-Velazquez, I.; Balderas-Navarro, R.E.; Ortega-Gallegos, J.; Guel-Sandoval, S.; Lastras-Martinez, L.F. [Instituto de Investigacion en Comunicacion Optica, Universidad Autonoma de San Luis Potosi, Alvaro Obregon 64, San Luis Potosi, SLP 78000 (Mexico)

    2008-07-01

    We report on in situ Reflectance Difference Spectroscopy measurements carried out on GaAs(001). Measurements were performed at temperatures of 580 C and 430 C, in both n and p-type doped films and for both (2 x 4) and c(4 x 4) reconstructions. Samples employed were grown by Molecular Beam Epitaxy with doping levels in the range from 10{sup 16}-10{sup 19} cm{sup -3}. We demonstrate the potential of Reflectance Difference Spectroscopy for impurity level determinations under growth conditions. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  13. Quasioptische Terahertz-Bauelemente

    OpenAIRE

    Busch, Stefan Frederik (M. Sc.)

    2016-01-01

    Die Dissertation „Quasioptische Terahertz-Bauelemente“ beschäftigt sich mit der Frage, in wieweit sich das 3D-Druck-Verfahren Fused Deposition Modeling (FDM) für die Herstellung von quasioptischen Komponenten für Terahertz-Strahlung eignet. Neben der grundlegenden Validierung des Verfahrens werden verschiedenste 3D-gedruckte Bauelemente vorgestellt. Der Fokus liegt hierbei auf innovativen und neuartigen Quasioptiken, wie Alvarez-Optiken, Axicons, variablen Beugungsgittern und Diffractive Opti...

  14. Near infrared reflectance spectroscopy for the fast identification of PVC-based films.

    Science.gov (United States)

    Laasonen, M; Rantanen, J; Harmia-Pulkkinen, T; Michiels, E; Hiltunen, R; Räsänen, M; Vuorela, H

    2001-07-01

    Near infrared (NIR) reflectance spectroscopy was used to develop a non-destructive and rapid qualitative method for the analysis of plastic films used by the pharmaceutical industry for blistering. Three types of films were investigated: 250 microm PVC [poly(vinyl chloride)] films, 250 microm PVC films coated with 40 g m(-2) of PVDC [poly(vinylidene dichloride)] and 250 microm PVC films coated with 5 g m(-2) of TE (Thermoelast) and 90 g m(-2) of PVDC. Three analyses were carried out using different pre-treatment options and a PLS (partial least squares) algorithm. Each analysis was aimed at identifying one type of film and rejecting all types of false sample (different thickness, colour or layer). True and false samples from four plastics manufacturers were included in the calibration sets in order to obtain robust methods that were suitable regardless of the supplier. Specificity was demonstrated by testing validation sets against the methods. The tests showed 0% of type I (false negative identification) and 1% of type II errors (false positive identification) for the PVC method, 13 and 3%, respectively, for the PVC-PVDC method and no error for the PVC-TE-PVDC method. Type II errors, mostly due to the slight sensitivity of the methods to film thickness, are easily corrected by simple thickness measurements. This study demonstrates that NIR spectroscopy is an excellent tool for the identification of PVC-based films. The three methods can be used by the pharmaceutical industry or plastics manufacturers for the quality control of films used in blister packaging.

  15. Plasma surface reflectance spectroscopy for non-invasive and continuous monitoring of extracellular component of blood

    Science.gov (United States)

    Sakota, Daisuke; Takatani, Setsuo

    2012-04-01

    To achieve the quantitative optical non-invasive diagnosis of blood during extracorporeal circulation therapies, the instrumental technique to extract extracellular spectra from whole blood was developed. In the circuit, the continuous blood flow was generated by a centrifugal blood pump. The oxygen saturation was maintained 100% by an oxygenator. The developed glass optical flow cell was attached to the outlet tubing of the oxygenator. The halogen lamp including the light from 400 to 900 nm wavelength was used for the light source. The light was guided into an optical fiber. The light emitted by the fiber was collimated and emitted to the flow cell flat surface at the incident angle of 45 degrees. The light just reflected on the boundary between inner surface of the flow cell and plasma at 45 degrees was detected by the detection fiber. The detected light was analyzed by a spectral photometer. The obtained spectrum from 400 to 600nm wavelength was not changed with respect to the hematocrit. In contrast, the signal in the spectral range was changed when the plasma free hemoglobin increased. By using two spectral range, 505+/-5 nm and 542.5+/-2.5 nm, the differential spectrum was correlated with the free hemoglobin at R2=0.99. On the other hand, as for the hematocrit, the differential spectrum was not correlated at R2=0.01. Finally, the plasma free hemoglobin was quantified with the accuracy of 22+/-19mg/dL. The result shows that the developed plasma surface reflectance spectroscopy (PSRS) can extract the plasma spectrum from flowing whole blood.

  16. Monitoring longitudinal changes in irradiated head and neck cancer xenografts using diffuse reflectance spectroscopy

    Science.gov (United States)

    Vishwanath, Karthik; Jiang, Shudong; Gunn, Jason R.; Marra, Kayla; Andreozzi, Jacqueline M.; Pogue, Brian W.

    2016-02-01

    Radiation therapy is often used as the preferred clinical treatment for control of localized head and neck cancer. However, during the course of treatment (6-8 weeks), feedback about functional and/or physiological changes within impacted tissue are not obtained, given the onerous financial and/or logistical burdens of scheduling MRI, PET or CT scans. Diffuse optical sensing is well suited to address this problem since the instrumentation can be made low-cost and portable while still being able to non-invasively provide information about vascular oxygenation in vivo. Here we report results from studies that employed an optical fiber-based portable diffuse reflectance spectroscopy (DRS) system to longitudinally monitor changes in tumor vasculature within two head and neck cancer cell lines (SCC-15 and FaDu) xenografted in the flanks of nude mice, in two separate experiments. Once the tumor volumes were 100mm3, 67% of animals received localized (electron beam) radiation therapy in five fractions (8Gy/day, for 5 days) while 33% of the animals served as controls. DRS measurements were obtained from each animal on each day of treatment and then for two weeks post-treatment. Reflectance spectra were parametrized to extract total hemoglobin concentration and blood oxygen-saturation and the resulting time-trends of optical parameters appear to be dissimilar for the two cell-lines. These findings are also compared to previous animal experiments (using the FaDu line) that were irradiated using a photon beam radiotherapy protocol. These results and implications for the use of fiber-based DRS measurements made at local (irradiated) tumor site as a basis for identifying early radiotherapy-response are presented and discussed.

  17. Analysis of total oil and fatty acids composition by near infrared reflectance spectroscopy in edible nuts

    Science.gov (United States)

    Kandala, Chari V.; Sundaram, Jaya

    2014-10-01

    Near Infrared (NIR) Reflectance spectroscopy has established itself as an important tool in quantifying water and oil present in various food materials. It is rapid and nondestructive, easier to use, and does not require processing the samples with corrosive chemicals that would render them non-edible. Earlier, the samples had to be ground into powder form before making any measurements. With the development of new soft ware packages, NIR techniques could now be used in the analysis of intact grain and nuts. While most of the commercial instruments presently available work well with small grain size materials such as wheat and corn, the method present here is suitable for large kernel size products such as shelled or in-shell peanuts. Absorbance spectra were collected from 400 nm to 2500 nm using a NIR instrument. Average values of total oil contents (TOC) of peanut samples were determined by standard extraction methods, and fatty acids were determined using gas chromatography. Partial least square (PLS) analysis was performed on the calibration set of absorption spectra, and models were developed for prediction of total oil and fatty acids. The best model was selected based on the coefficient of determination (R2), Standard error of prediction (SEP) and residual percent deviation (RPD) values. Peanut samples analyzed showed RPD values greater than 5.0 for both absorbance and reflectance models and thus could be used for quality control and analysis. Ability to rapidly and nondestructively measure the TOC, and analyze the fatty acid composition, will be immensely useful in peanut varietal improvement as well as in the grading process of grain and nuts.

  18. Simultaneous estimation of transcutaneous bilirubin, hemoglobin, and melanin based on diffuse reflectance spectroscopy

    Science.gov (United States)

    Nishidate, Izumi; Abdul, Wares MD.; Ohtsu, Mizuki; Nakano, Kazuya; Haneishi, Hideaki

    2018-02-01

    We propose a method to estimate transcutaneous bilirubin, hemoglobin, and melanin based on the diffuse reflectance spectroscopy. In the proposed method, the Monte Carlo simulation-based multiple regression analysis for an absorbance spectrum in the visible wavelength region (460-590 nm) is used to specify the concentrations of bilirubin (Cbil), oxygenated hemoglobin (Coh), deoxygenated hemoglobin (Cdh), and melanin (Cm). Using the absorbance spectrum calculated from the measured diffuse reflectance spectrum as a response variable and the extinction coefficients of bilirubin, oxygenated hemoglobin, deoxygenated hemoglobin, and melanin, as predictor variables, multiple regression analysis provides regression coefficients. Concentrations of bilirubin, oxygenated hemoglobin, deoxygenated hemoglobin, and melanin, are then determined from the regression coefficients using conversion vectors that are numerically deduced in advance by the Monte Carlo simulations for light transport in skin. Total hemoglobin concentration (Cth) and tissue oxygen saturation (StO2) are simply calculated from the oxygenated hemoglobin and deoxygenated hemoglobin. In vivo animal experiments with bile duct ligation in rats demonstrated that the estimated Cbil is increased after ligation of bile duct and reaches to around 20 mg/dl at 72 h after the onset of the ligation, which corresponds to the reference value of Cbil measured by a commercially available transcutaneous bilirubin meter. We also performed in vivo experiments with rats while varying the fraction of inspired oxygen (FiO2). Coh and Cdh decreased and increased, respectively, as FiO2 decreased. Consequently, StO2 was dramatically decreased. The results in this study indicate potential of the method for simultaneous evaluation of multiple chromophores in skin tissue.

  19. Diffuse-reflectance fourier-transform mid-infrared spectroscopy as a method of characterizing changes in soil organic matter

    Science.gov (United States)

    Diffuse-Reflectance Fourier-Transform Mid-Infrared Spectroscopy (MidIR) can identify the presence of important organic functional groups in soil organic matter (SOM). Soils contain myriad organic and inorganic components that absorb in the MidIR so spectral interpretation needs to be validated in or...

  20. Real-time in vivo tissue characterization with diffuse reflectance spectroscopy during transthoracic lung biopsy: a clinical feasibility study

    NARCIS (Netherlands)

    Spliethoff, Jarich; Prevoo, Warner; Meier, Mark A.J.; de Jong, Jeroen; Evers, Daniel; Evers, Daniel J.; Sterenborg, Hendricus J.C.M.; Lucassen, Gerald; Lucassen, Gerald W.; Hendriks, Benno H.W.; Ruers, Theo J.M.

    2016-01-01

    Purpose: This study presents the first in vivo real-time tissue characterization during image-guided percutaneous lung biopsies using diffuse reflectance spectroscopy (DRS) sensing at the tip of a biopsy needle with integrated optical fibers. Experimental Design: Tissues from 21 consented patients

  1. Improvement of direct determination of trace nickel in environmental samples by diffuse reflection spectroscopy using chromaticity characteristics.

    Science.gov (United States)

    Ershova, N I; Ivanov, V M

    2000-05-01

    Cellulose and chromaton-N-super as solid supports for direct determination of the immobilized nickel complexes with dimethylglyoxime and benzyldioxime by diffuse reflection spectroscopy were compared. The advantage of chromaton-N-super with use of benzyldioxime is shown. Detection limit is 0.02 microg/mL. The proposed method was applied for the analysis of soil.

  2. Secondary cell wall development in cotton fibers as examined with attenuated total reflection Fourier transform infrared spectroscopy

    Science.gov (United States)

    Cotton fibers harvested at 18, 20, 24, 28, 32, 36 and 40 days after flowering were examined using attenuated total reflection Fourier transform-infrared (ATR FT-IR) spectroscopy. The selected harvesting points coincide with secondary cell wall (SCW) development in the fibers. Progressive but moderat...

  3. Adsorption of the cysteine–tryptophan dipeptide at the Au(110)/liquid interface studied using reflection anisotropy spectroscopy

    DEFF Research Database (Denmark)

    Morozzo della Rocca, Blasco; Smith, C I; Tesauro, Cinzia

    2010-01-01

    The adsorption of a cysteine–tryptophan dipeptide has been monitored at a Au(110)/electrolyte interface using reflection anisotropy spectroscopy. At −0.6 V the dipeptide adsorbed through the formation of Au–S bonds and a link between the NH2 group at the Au surface. As the applied potential...

  4. Prediction of biogas yield and its kinetics in reed canary grass using near infrared reflectance spectroscopy and chemometrics

    DEFF Research Database (Denmark)

    Kandel, Tanka Prasad; Gislum, René; Jørgensen, Uffe

    2013-01-01

    A rapid method is needed to assess biogas and methane yield potential of various kinds of substrate prior to anaerobic digestion. This study reports near infrared reflectance spectroscopy (NIRS) as a rapid alternative method to the conventional batch methods for prediction of specific biogas yield...

  5. DETERMINING PARAMETERS OF THE DIELECTRIC FUNCTION OF A SUBSTANCE IN AQUEOUS SOLUTION BY SELF-REFERENCED REFLECTION THZ SPECTROSCOPY

    DEFF Research Database (Denmark)

    2008-01-01

    Method and apparatus for determining dielectric function of liquid solutions and thereby concentrations of substances in aqueous solution or the volatile/non-volatile nature of the liquid by self-referenced reflection THz spectroscopy. Having the aqueous solution in any container with a window al....... The invention is particularly useful for determining alcohol (ethanol) content in aqueous solution containing other substances and particles....

  6. Conformational aspects of proteins at the air/water interface studied by infrared reflection-adsorption spectroscopy

    NARCIS (Netherlands)

    Martin, A.H.; Meinders, M.B.J.; Bos, M.A.; Cohen Stuart, M.A.; Vliet, van T.

    2003-01-01

    From absorption spectra obtained with infrared reflection-absorption spectroscopy (IRRAS), it is possible to obtain information on conformational changes at a secondary folding level of proteins adsorbed at the air/water interface. In addition, information on protein concentration at the interface

  7. Conformational aspects of proteins at the air/water interface studied by infrared reflection-absorption spectroscopy

    NARCIS (Netherlands)

    Martin, A.H.; Meinders, M.B.J.; Bos, M.A.; Cohen Stuart, M.A.; Vliet, T. van

    2003-01-01

    From absorption spectra obtained with infrared reflection - absorption spectroscopy (IRRAS), it is possible to obtain information on conformational changes at a secondary folding level of proteins adsorbed at the air/water interface. In addition, information on protein concentration at the interface

  8. Quantification of betaglucans, lipid and protein contents in whole oat groats (Avena sativa L.) using near infrared reflectance spectroscopy

    Science.gov (United States)

    Whole oat has been described as an important healthy food for humans due to its beneficial nutritional components. Near infrared reflectance spectroscopy (NIRS) is a powerful, fast, accurate and non-destructive analytical tool that can be substituted for some traditional chemical analysis. A total o...

  9. Terahertz broadband polarization converter based on metamaterials

    Science.gov (United States)

    Li, Yonghua; Zhao, Guozhong

    2018-01-01

    Based on the metamaterial composed of symmetrical split resonant ring, a broadband reflective terahertz polarization converter is proposed. The numerical simulation shows that it can rotate the polarization direction of linear polarized wave 90° in the range of 0.7-1.8THz and the polarization conversion ratio is over 90%. The reflection coefficient of the two electric field components in the diagonal direction is the same and the phase difference is 180° ,which leads to the cross-polarization rotation.In order to further study the physical mechanism of high polarization conversion, we analyze the surface current distribution of the resonant ring. The polarization converter has potential applications in terahertz wave plate and metamaterial antenna design.

  10. Quantitative Analysis of Total Petroleum Hydrocarbons in Soils: Comparison between Reflectance Spectroscopy and Solvent Extraction by 3 Certified Laboratories

    Directory of Open Access Journals (Sweden)

    Guy Schwartz

    2012-01-01

    Full Text Available The commonly used analytic method for assessing total petroleum hydrocarbons (TPH in soil, EPA method 418.1, is usually based on extraction with 1,1,2-trichlorotrifluoroethane (Freon 113 and FTIR spectroscopy of the extracted solvent. This method is widely used for initial site investigation, due to the relative low price per sample. It is known that the extraction efficiency varies depending on the extracting solvent and other sample properties. This study’s main goal was to evaluate reflectance spectroscopy as a tool for TPH assessment, as compared with three commercial certified laboratories using traditional methods. Large variations were found between the results of the three commercial laboratories, both internally (average deviation up to 20%, and between laboratories (average deviation up to 103%. Reflectance spectroscopy method was found be as good as the commercial laboratories in terms of accuracy and could be a viable field-screening tool that is rapid, environmental friendly, and cost effective.

  11. [Near-infrared reflectance spectroscopy predicts protein, moisture and ash in beans].

    Science.gov (United States)

    Gao, Huiyu; Wang, Guodong; Men, Jianhua; Wang, Zhu

    2017-05-01

    To explore the potential of near-infrared reflectance( NIR)spectroscopy to determine macronutrient contents in beans. NIR spectra and analytical measurements of protein, moisture and ash were collected from 70 kinds of beans. Reference methods were used to analyze all the ground beans samples. NIR spectra on intact and ground beans samples were registered. Partial least-squares( PLS)regression models were developed with principal components analysis( PCA) to assign 49 bean accessions to a calibration data set and 21 accessions to an external validation set. For intact beans, the relative predictive determinant( RPD) values for protein and ash( 3. 67 and 3. 97, respectively) were good for screening. RPD value for moisture was only 1. 39, which was not recommended. For ground beans, the RPD values for protein, moisture and ash( 6. 63, 5. 25 and 3. 57, respectively) were good enough for screening. The protein, moisture and ash levels for intact and ground beans were all significantly correlated( P beans with no or easy sample preparation.

  12. Quality evaluation of regional forage resources by means of near infrared reflectance spectroscopy

    Directory of Open Access Journals (Sweden)

    Bruno Ronchi

    2010-01-01

    Full Text Available Quality parameters of grassland and pasture samples collected during a three-year period at two environmentally andgeographically different areas were analysed by Near Infrared Reflectance Spectroscopy (NIRS. Chemical analysis forcrude protein (CP, crude fibre (CF, neutral detergent fibre (NDF, acid detergent fibre (ADF, acid detergent lignin (ADLand crude ash (ASH carried out on two-thirds of the samples were used in calibration processes. The remaining onethirdof the data was used to validate the best calibrations obtained. Samples selection is discussed. Different math pretreatments(derivative, gap, primary smoothing and secondary smoothing, light scattering correction methods and calibrationalgorithms were tested to achieve the better predictive performances. We obtained the best results using differentregression algorithms to correlate spectral information to chemical data. For CP (R2 = 0.94, SEP=1.3, NDF (R2 =0.95, SEP = 2.14 and ADF (R2 = 0.92, SEP=2.06 Multiple Linear Regression (MLR models fit chemical data better thanMean Partial Least Square (MPLS regression. A molecular basis explanation of wavelengths selected was carried out.MPLS models worked well for CF (R2 = 0.93, SEP=1.57, and ASH (R2 = 0.95, SEP=1.17 while poor calibrations wereobtained for ADL using both algorithms. To confirm the reliability of the models developed, uncertainties of predictionswere compared with findings on nutritional variations and animal performances.

  13. Diffuse reflectance spectroscopy as a tool for real-time tissue assessment during colorectal cancer surgery

    Science.gov (United States)

    Baltussen, Elisabeth J. M.; Snaebjornsson, Petur; de Koning, Susan G. Brouwer; Sterenborg, Henricus J. C. M.; Aalbers, Arend G. J.; Kok, Niels; Beets, Geerard L.; Hendriks, Benno H. W.; Kuhlmann, Koert F. D.; Ruers, Theo J. M.

    2017-10-01

    Colorectal surgery is the standard treatment for patients with colorectal cancer. To overcome two of the main challenges, the circumferential resection margin and postoperative complications, real-time tissue assessment could be of great benefit during surgery. In this ex vivo study, diffuse reflectance spectroscopy (DRS) was used to differentiate tumor tissue from healthy surrounding tissues in patients with colorectal neoplasia. DRS spectra were obtained from tumor tissue, healthy colon, or rectal wall and fat tissue, for every patient. Data were randomly divided into training (80%) and test (20%) sets. After spectral band selection, the spectra were classified using a quadratic classifier and a linear support vector machine. Of the 38 included patients, 36 had colorectal cancer and 2 had an adenoma. When the classifiers were applied to the test set, colorectal cancer could be discriminated from healthy tissue with an overall accuracy of 0.95 (±0.03). This study demonstrates the possibility to separate colorectal cancer from healthy surrounding tissue by applying DRS. High classification accuracies were obtained both in homogeneous and inhomogeneous tissues. This is a fundamental step toward the development of a tool for real-time in vivo tissue assessment during colorectal surgery.

  14. Attenuated total reflectance-FT-IR spectroscopy for gunshot residue analysis: potential for ammunition determination.

    Science.gov (United States)

    Bueno, Justin; Sikirzhytski, Vitali; Lednev, Igor K

    2013-08-06

    The ability to link a suspect to a particular shooting incident is a principal task for many forensic investigators. Here, we attempt to achieve this goal by analysis of gunshot residue (GSR) through the use of attenuated total reflectance (ATR) Fourier transform infrared spectroscopy (FT-IR) combined with statistical analysis. The firearm discharge process is analogous to a complex chemical process. Therefore, the products of this process (GSR) will vary based upon numerous factors, including the specific combination of the firearm and ammunition which was discharged. Differentiation of FT-IR data, collected from GSR particles originating from three different firearm-ammunition combinations (0.38 in., 0.40 in., and 9 mm calibers), was achieved using projection to latent structures discriminant analysis (PLS-DA). The technique was cross (leave-one-out), both internally and externally, validated. External validation was achieved via assignment (caliber identification) of unknown FT-IR spectra from unknown GSR particles. The results demonstrate great potential for ATR-FT-IR spectroscopic analysis of GSR for forensic purposes.

  15. Quantum state-resolved gas/surface reaction dynamics probed by reflection absorption infrared spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Chen Li [Department of Dynamics at Surfaces, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, Goettingen (Germany); Ueta, Hirokazu; Beck, Rainer D. [Laboratoire de Chimie Physique Moleculaire, Ecole Polytechnique Federale de Lausanne (Switzerland); Bisson, Regis [Aix-Marseille Universite, PIIM, CNRS, UMR 7345, 13397 Marseille (France)

    2013-05-15

    We report the design and characterization of a new molecular-beam/surface-science apparatus for quantum state-resolved studies of gas/surface reaction dynamics combining optical state-specific reactant preparation in a molecular beam by rapid adiabatic passage with detection of surface-bound reaction products by reflection absorption infrared spectroscopy (RAIRS). RAIRS is a non-invasive infrared spectroscopic detection technique that enables online monitoring of the buildup of reaction products on the target surface during reactant deposition by a molecular beam. The product uptake rate obtained by calibrated RAIRS detection yields the coverage dependent state-resolved reaction probability S({theta}). Furthermore, the infrared absorption spectra of the adsorbed products obtained by the RAIRS technique provide structural information, which help to identify nascent reaction products, investigate reaction pathways, and determine branching ratios for different pathways of a chemisorption reaction. Measurements of the dissociative chemisorption of methane on Pt(111) with this new apparatus are presented to illustrate the utility of RAIRS detection for highly detailed studies of chemical reactions at the gas/surface interface.

  16. [Progress in application of near infrared reflectance spectroscopy to the study of ruminant nutrition].

    Science.gov (United States)

    Guo, Xu-Sheng; Shang, Zhan-Huan; Fang, Xiang-Wen; Long, Rui-Jun

    2009-03-01

    The near infrared reflectance spectroscopy (NIRS) technique has been widely used in the study of ruminant nutrition with many of its operational merits such as facility, shortcut and accuracy, etc. Study suggested that the standard error of cross-validation (SECV) ranges from 1.6% to 2.8% in predicting organic matter digestion of ruminant diet by using the NIRS technique; the chemical and biological compositions and the microbial protein proportion in the duodenal digesta can be predicted accurately using the NIRS. However, the kinetic parameters of degradation are not well predicted; The prediction of intake of stall feeding animals by using NIRS is similar to the determination of in vivo method, but the standard error of prediction is about 14% when using the NIRS to predict intake of grazing animals. All of the studies suggest that big progress has been made in using NIRS technique to predict feed digestion and evaluate the diet quality and intake of ruminant animals, which also suggest that the NIRS technique has a wide prospect in the study of ruminant nutrition.

  17. Crop/weed discrimination using near-infrared reflectance spectroscopy (NIRS)

    Science.gov (United States)

    Zhang, Yun; He, Yong

    2006-09-01

    The traditional uniform herbicide application often results in an over chemical residues on soil, crop plants and agriculture produce, which have imperiled the environment and food security. Near-infrared reflectance spectroscopy (NIRS) offers a promising means for weed detection and site-specific herbicide application. In laboratory, a total of 90 samples (30 for each species) of the detached leaves of two weeds, i.e., threeseeded mercury (Acalypha australis L.) and fourleafed duckweed (Marsilea quadrfolia L.), and one crop soybean (Glycine max) was investigated for NIRS on 325- 1075 nm using a field spectroradiometer. 20 absorbance samples of each species after pretreatment were exported and the lacked Y variables were assigned independent values for partial least squares (PLS) analysis. During the combined principle component analysis (PCA) on 400-1000 nm, the PC1 and PC2 could together explain over 91% of the total variance and detect the three plant species with 98.3% accuracy. The full-cross validation results of PLS, i.e., standard error of prediction (SEP) 0.247, correlation coefficient (r) 0.954 and root mean square error of prediction (RMSEP) 0.245, indicated an optimum model for weed identification. By predicting the remaining 10 samples of each species in the PLS model, the results with deviation presented a 100% crop/weed detection rate. Thus, it could be concluded that PLS was an available alternative of for qualitative weed discrimination on NTRS.

  18. Non-invasive detection of periodontal disease using diffuse reflectance spectroscopy: a clinical study

    Science.gov (United States)

    Prasanth, Chandra Sekhar; Betsy, Joseph; Subhash, Narayanan; Jayanthi, Jayaraj L.; Prasanthila, Janam

    2012-03-01

    In clinical diagnostic procedures, gingival inflammation is considered as the initial stage of periodontal breakdown. This is often detected clinically by bleeding on probing as it is an objective measure of inflammation. Since conventional diagnostic procedures have several inherent drawbacks, development of novel non-invasive diagnostic techniques assumes significance. This clinical study was carried out in 15 healthy volunteers and 25 patients to demonstrate the applicability of diffuse reflectance (DR) spectroscopy for quantification and discrimination of various stages of inflammatory conditions in periodontal disease. The DR spectra of diseased lesions recorded using a point monitoring system consisting of a tungsten halogen lamp and a fiber-optic spectrometer showed oxygenated hemoglobin absorption dips at 545 and 575 nm. Mean DR spectra on normalization shows marked differences between healthy and different stages of gingival inflammation. Among the various DR intensity ratios investigated, involving oxy Hb absorption peaks, the R620/R575 ratio was found to be a good parameter of gingival inflammation. In order to screen the entire diseased area and its surroundings instantaneously, DR images were recorded with an EMCCD camera at 620 and 575 nm. We have observed that using the DR image intensity ratio R620/R575 mild inflammatory tissues could be discriminated from healthy with a sensitivity of 92% and specificity of 93%, and from moderate with a sensitivity of 83% and specificity of 96%. The sensitivity and specificity obtained between moderate and severe inflammation are 82% and 76% respectively.

  19. Using visible reflectance spectroscopy to reconstruct historical changes in chlorophyll a concentration in East Antarctic ponds

    Directory of Open Access Journals (Sweden)

    Qianqian Chen

    2013-12-01

    Full Text Available The visible reflectance spectroscopy (VRS and chlorophyll a concentration were determined in three sediment profiles collected from East Antarctica to investigate the potential application of VRS in reconstructing historical changes in Antarctic lake primary productivity. The results showed that the appearance of a trough at 650–700 nm is an important marker for chlorophyll a concentration and can therefore be used to distinguish the sedimentary organic matter source from guano and algae. The measured chlorophyll a content had significant positive correlations with the trough area between 650 and 700 nm, and no distinct trough was found in the sediments with organic matter completely derived from guano. Modelling results showed that the spectra spectrally inferred chlorophyll a content, and the measured data exhibit consistent trends with depth, showing that the dimensionless trough area can serve as an independent proxy for reconstructing historical fluctuations in the primary production of Antarctic ponds. The correlation of phosphorus (P with measured and inferred chlorophyll a contents in ornithogenic sediments near penguin colonies indicates that the change in primary productivity in the Antarctic ponds investigated was closely related to the amount of guano input from these birds.

  20. Detection of sibutramine in adulterated dietary supplements using attenuated total reflectance-infrared spectroscopy.

    Science.gov (United States)

    Deconinck, E; Cauwenbergh, T; Bothy, J L; Custers, D; Courselle, P; De Beer, J O

    2014-11-01

    Sibutramine is one of the most occurring adulterants encountered in dietary supplements with slimming as indication. These adulterated dietary supplements often contain a herbal matrix. When customs intercept these kind of supplements it is almost impossible to discriminate between the legal products and the adulterated ones, due to misleading packaging. Therefore in most cases these products are confiscated and send to laboratories for analysis. This results inherently in the confiscation of legal, non-adulterated products. Therefore there is a need for easy to use equipment and techniques to perform an initial screening of samples. Attenuated total reflectance-infrared (ATR-IR) spectroscopy was evaluated for the detection of sibutramine in adulterated dietary supplements. Data interpretation was performed using different basic chemometric techniques. It was found that the use of ATR-IR combined with the k-Nearest Neighbours (k-NN) was able to detect all adulterated dietary supplements in an external test set and this with a minimum of false positive results. This means that a small amount of legal products will still be confiscated and analyzed in a laboratory to be found negative, but no adulterated samples will pass the initial ATR-IR screening. Copyright © 2014 Elsevier B.V. All rights reserved.

  1. Phase transitions of amorphous solid acetone in confined geometry investigated by reflection absorption infrared spectroscopy.

    Science.gov (United States)

    Shin, Sunghwan; Kang, Hani; Kim, Jun Soo; Kang, Heon

    2014-11-26

    We investigated the phase transformations of amorphous solid acetone under confined geometry by preparing acetone films trapped in amorphous solid water (ASW) or CCl4. Reflection absorption infrared spectroscopy (RAIRS) and temperature-programmed desorption (TPD) were used to monitor the phase changes of the acetone sample with increasing temperature. An acetone film trapped in ASW shows an abrupt change in the RAIRS features of the acetone vibrational bands during heating from 80 to 100 K, which indicates the transformation of amorphous solid acetone to a molecularly aligned crystalline phase. Further heating of the sample to 140 K produces an isotropic solid phase, and eventually a fluid phase near 157 K, at which the acetone sample is probably trapped in a pressurized, superheated condition inside the ASW matrix. Inside a CCl4 matrix, amorphous solid acetone crystallizes into a different, isotropic structure at ca. 90 K. We propose that the molecularly aligned crystalline phase formed in ASW is created by heterogeneous nucleation at the acetone-water interface, with resultant crystal growth, whereas the isotropic crystalline phase in CCl4 is formed by homogeneous crystal growth starting from the bulk region of the acetone sample.

  2. Diffuse reflectance spectroscopy and optical polarization imaging of in-vivo biological tissue

    Science.gov (United States)

    Mora-Núñez, A.; Castillejos, Y.; García-Torales, G.; Martínez-Ponce, G.

    2013-11-01

    A number of optical techniques have been reported in the scientific literature as accomplishable methodologies to diagnose diseases in biological tissue, for instance, diffuse reflectance spectroscopy (DRS) and optical polarization imaging (OPI). The skin is the largest organ in the body and consists of three primary layers, namely, the epidermis (the outermost layer exposed to the world), the dermis, and the hypodermis. The epidermis changes from to site to site, mainly because of difference in hydration. A lower water content increase light scattering and reduce the penetration depth of radiation. In this work, two hairless mice have been selected to evaluate their skin features by using DRS and OPI. Four areas of the specimen body were chosen to realize the comparison: back, abdomen, tail, and head. From DRS, it was possible to distinguish the skin nature because of different blood irrigation at dermis. In the other hand, OPI shows pseudo-depolarizing regions in the measured Mueller images related to a spatially varying propagation of the scattered light. This provides information about the cell size in the irradiated skin.

  3. Surface energy loss processes in XPS studied by absolute reflection electron energy loss spectroscopy

    International Nuclear Information System (INIS)

    Nagatomi, T.; Goto, K.

    2010-01-01

    The results of the investigation of the inelastic interaction of 300-3000 eV electrons with the Ni and Au surfaces by the analysis of absolute reflection electron energy loss spectroscopy (REELS) spectra were described. The present analysis enables the inelastic mean free path (IMFP), surface excitation parameter (SEP) and differential SEP (DSEP) to be obtained simultaneously from an absolute REELS spectrum. The obtained IMFPs for Ni and Au showed a good agreement with those calculated using the TPP-2M predictive equation. The present SEPs determined for Ni and Au were fitted to the Chen's formula describing the dependence of the SEP on the electron energy, and material parameters for Ni and Au in Chen's formula were proposed. The present DESPs were compared with the theoretical results, and a reasonable agreement between the experimentally determined DSEPs and theoretical results was confirmed. The MC modeling of calculating the REELS spectrum, in which energy loss processes due to surface excitations are taken into account, was also described. The IMFP, SEP and DSEP determined by the present absolute REELS analysis were employed to describe energy loss processes by inelastic scattering in the proposed MC simulation. The simulated REELS spectra were found to be in a good agreement with the experimental spectra for both Ni and Au.

  4. Laser spectroscopy of francium isotopes at the borders of the region of reflection asymmetry

    CERN Document Server

    Budinčević, I; Bissell, M L; Cocolios, T E; de Groote, R P; De Schepper, S; Fedosseev, V N; Flanagan, K T; Franchoo, S; Garcia Ruiz, R F; Heylen, H; Lynch, K M; Marsh, B A; Neyens, G; Procter, T J; Rossel, R E; Rothe, S; Strashnov, I; Stroke, H H; Wendt, K D A

    2014-01-01

    The magnetic dipole moments and changes in mean-square charge radii of the neutron-rich $^{218m,219,229,231}\\text{Fr}$ isotopes were measured with the newly-installed Collinear Resonance Ionization Spectroscopy (CRIS) beam line at ISOLDE, CERN, probing the $7s~^{2}S_{1/2}$ to $8p~^{2}P_{3/2}$ atomic transition. The $\\delta\\langle r^{2}\\rangle^{A,221}$ values for $^{218m,219}\\text{Fr}$ and $^{229,231}\\text{Fr}$ follow the observed increasing slope of the charge radii beyond $N~=~126$. The charge radii odd-even staggering in this neutron-rich region is discussed, showing that $^{220}\\text{Fr}$ has a weakly inverted odd-even staggering while $^{228}\\text{Fr}$ has normal staggering. This suggests that both isotopes reside at the borders of a region of inverted staggering, which has been associated with reflection-asymmetric shapes. The $g(^{219}\\text{Fr}) = +0.69(1)$ value supports a $\\pi 1h_{9/2}$ shell model configuration for the ground state. The $g(^{229,231}\\text{Fr})$ values support the tentative $I^{\\pi}(^...

  5. Predicting glycogen concentration in the foot muscle of abalone using near infrared reflectance spectroscopy (NIRS).

    Science.gov (United States)

    Fluckiger, Miriam; Brown, Malcolm R; Ward, Louise R; Moltschaniwskyj, Natalie A

    2011-06-15

    Near infrared reflectance spectroscopy (NIRS) was used to predict glycogen concentrations in the foot muscle of cultured abalone. NIR spectra of live, shucked and freeze-dried abalones were modelled against chemically measured glycogen data (range: 0.77-40.9% of dry weight (DW)) using partial least squares (PLS) regression. The calibration models were then used to predict glycogen concentrations of test abalone samples and model robustness was assessed from coefficient of determination of the validation (R2(val)) and standard error of prediction (SEP) values. The model for freeze-dried abalone gave the best prediction (R2(val) 0.97, SEP=1.71), making it suitable for quantifying glycogen. Models for live and shucked abalones had R2(val) of 0.86 and 0.90, and SEP of 3.46 and 3.07 respectively, making them suitable for producing estimations of glycogen concentration. As glycogen is a taste-active component associated with palatability in abalone, this study demonstrated the potential of NIRS as a rapid method to monitor the factors associated with abalone quality. Copyright © 2011 Elsevier Ltd. All rights reserved.

  6. Forensic Hair Differentiation Using Attenuated Total Reflection Fourier Transform Infrared (ATR FT-IR) Spectroscopy.

    Science.gov (United States)

    Manheim, Jeremy; Doty, Kyle C; McLaughlin, Gregory; Lednev, Igor K

    2016-07-01

    Hair and fibers are common forms of trace evidence found at crime scenes. The current methodology of microscopic examination of potential hair evidence is absent of statistical measures of performance, and examiner results for identification can be subjective. Here, attenuated total reflection (ATR) Fourier transform-infrared (FT-IR) spectroscopy was used to analyze synthetic fibers and natural hairs of human, cat, and dog origin. Chemometric analysis was used to differentiate hair spectra from the three different species, and to predict unknown hairs to their proper species class, with a high degree of certainty. A species-specific partial least squares discriminant analysis (PLSDA) model was constructed to discriminate human hair from cat and dog hairs. This model was successful in distinguishing between the three classes and, more importantly, all human samples were correctly predicted as human. An external validation resulted in zero false positive and false negative assignments for the human class. From a forensic perspective, this technique would be complementary to microscopic hair examination, and in no way replace it. As such, this methodology is able to provide a statistical measure of confidence to the identification of a sample of human, cat, and dog hair, which was called for in the 2009 National Academy of Sciences report. More importantly, this approach is non-destructive, rapid, can provide reliable results, and requires no sample preparation, making it of ample importance to the field of forensic science. © The Author(s) 2016.

  7. Noninvasive method for the assessment of dermal uptake of pesticides using attenuated total reflectance infrared spectroscopy.

    Science.gov (United States)

    Carden, Angela; Yost, Michael G; Fenske, Richard A

    2005-03-01

    Dermal absorption of pesticides is a primary exposure route for agricultural workers, but is not well characterized. Current measurement techniques are either invasive, such as tape-stripping, or require extensive sample preparation or analysis time, such as urinary metabolite monitoring or wipe sampling followed by gas chromatography analysis. We present the application of a noninvasive, spectroscopic approach for the measurement of pesticide absorption into skin. Attenuated total reflectance infrared spectroscopy (ATR-IR) was used to monitor directly the absorption of two pesticides--captan and azinphos-methyl--in ten volunteers over 20 min under occlusive conditions. We found substantial variability in absorption across subjects. Our results were comparable to those measured by the more traditional method of wipe-sampling followed by extraction and gas chromatography analysis. Multivariate data analysis, in the form of multivariate curve resolution (MCR), is a novel addition to this type of experiment, yielding time-resolved information unachievable by standard methods. These data are potentially more informative than the monitoring of blood or urinary metabolites because they can be acquired in essentially real-time, allowing observations of pesticide absorption on a rapid timescale rather than over hours or days.

  8. Attenuated total internal reflection Fourier transform infrared spectroscopy: a quantitative approach for kidney stone analysis.

    Science.gov (United States)

    Gulley-Stahl, Heather J; Haas, Jennifer A; Schmidt, Katherine A; Evan, Andrew P; Sommer, André J

    2009-07-01

    The impact of kidney stone disease is significant worldwide, yet methods for quantifying stone components remain limited. A new approach requiring minimal sample preparation for the quantitative analysis of kidney stone components has been investigated utilizing attenuated total internal reflection Fourier transform infrared spectroscopy (ATR-FT-IR). Calcium oxalate monohydrate (COM) and hydroxylapatite (HAP), two of the most common constituents of urinary stones, were used for quantitative analysis. Calibration curves were constructed using integrated band intensities of four infrared absorptions versus concentration (weight %). The correlation coefficients of the calibration curves range from 0.997 to 0.93. The limits of detection range from 0.07 +/- 0.02% COM/HAP where COM is the analyte and HAP is the matrix, to 0.26 +/- 0.07% HAP/COM where HAP is the analyte and COM is the matrix. This study shows that linear calibration curves can be generated for the quantitative analysis of stone mixtures provided the system is well understood especially with respect to particle size.

  9. Terahertz-infrared spectroscopy of overdoped manganites La{sub 1−x}Ca{sub x}MnO{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Kadyrov, Lenar S., E-mail: kadyrov@phystech.edu [Moscow Institute of Physics and Technology (State University), Institutskiy Pereulok 9, Dolgoprudny 141700 (Russian Federation); A.M. Prokhorov General Physics Institute, Russian Academy of Sciences, Vavilov Str., 38, Moscow 119991 (Russian Federation); Zhukova, Elena S. [Moscow Institute of Physics and Technology (State University), Institutskiy Pereulok 9, Dolgoprudny 141700 (Russian Federation); A.M. Prokhorov General Physics Institute, Russian Academy of Sciences, Vavilov Str., 38, Moscow 119991 (Russian Federation); 1. Physikalisches Institut, Universität Stuttgart, Pfaffenwaldring 57, Stuttgart 70550 (Germany); Torgashev, Victor I. [Faculty of Physics, Southern Federal University, Bolshaya Sadovaya 105/42, Rostov-on-Don 344090 (Russian Federation); Gorshunov, Boris P. [Moscow Institute of Physics and Technology (State University), Institutskiy Pereulok 9, Dolgoprudny 141700 (Russian Federation); A.M. Prokhorov General Physics Institute, Russian Academy of Sciences, Vavilov Str., 38, Moscow 119991 (Russian Federation); 1. Physikalisches Institut, Universität Stuttgart, Pfaffenwaldring 57, Stuttgart 70550 (Germany); Prokhorov, Anatoly S.; Motovilova, Elizaveta A. [Moscow Institute of Physics and Technology (State University), Institutskiy Pereulok 9, Dolgoprudny 141700 (Russian Federation); A.M. Prokhorov General Physics Institute, Russian Academy of Sciences, Vavilov Str., 38, Moscow 119991 (Russian Federation); Fischgrabe, Florian; Moshnyaga, Vasily [1. Physikalisches Institut, Georg-August-Universität Göttingen, Fredrich-Hund-Platz 1, Göttingen 37077 (Germany); Zhang, Tao [Key Laboratory of Material Physics, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031 (China); and others

    2015-03-01

    Terahertz and infrared spectra of dielectric permittivity and optical conductivity of overdoped manganites La{sub 1−x}Ca{sub x}MnO{sub 3} (0.5≤x≤1) have been measured at frequencies ν from 4 cm{sup −1} to 700 cm{sup −1} and at temperatures T from 5 K to 300 K. The samples were prepared in the form of bulk polycrystals (ceramics) and epitaxial films (free-standing and on MgO substrates). Strongly asymmetric absorption bands have been found in the compounds which are in charge-ordered state (0.5

  10. Assessment of biophysical tumor response to PDT in pancreatic cancer using localized reflectance spectroscopy

    Science.gov (United States)

    Isabelle, Martin; Klubben, William; He, Ting; Laughney, Ashley M.; Glaser, Adam; Krishnaswamy, Venkataramanan; Hoopes, P. Jack; Hasan, Tayyaba; Pogue, Brian W.

    2011-02-01

    Biophysical changes such as inflammation and necrosis occur immediately following PDT and may be used to assess the treatment response to PDT treatment in-vivo. This study uses localized reflectance measurements to quantify the scatter changes in tumor tissue occurring in response to verteporfin-based PDT treatment in xenograft pancreas tumors. Nude mice were implanted with subcutaneous AsPC-1 pancreatic tumors cells in matrigel, and allowed to establish solid tumors near 100mm3 volume. The mice were sensitized with 1mg/kg of the active component of verteporfin (benzoporphryin derivative, BPD), one hour before light delivery. The optical irradiation was performed using a 1 cm cylindrical interstitial diffusing tip fiber with 20J of red light (690nm). Tumor tissue was excised progressively and imaged, from 1 day to 4 weeks, after PDT treatment. The tissue sections were stained and analyzed by an expert veterinary pathologist, who provided information on tissue regions of interest. This information was correlated with variations in scattering and absorption parameters elucidated from the spectral images and the degree of necrosis and inflammation involvement was identified. Areas of necrosis and dead cells exhibited the lowest average scatter irradiance signature (3.78 and 4.07 respectively) compared to areas of viable pancreatic tumor cells and areas of inflammation (5.81 and 7.19 respectively). Bilirubin absorbance parameters also showed a lower absorbance value in necrotic tissue and areas of dead cells (0.05 and 0.1 respectively) compared to tissue areas for viable pancreatic tumor cells and areas of inflammation (0.28 and 0.35). These results demonstrate that localized reflectance spectroscopy is an imaging modality that can be used to identify tissue features associated with PDT treatment (e.g. necrosis and inflammation) that can be correlated with histopathologically-reviewed H&E stained slides. Further study of this technique may provide means for automated

  11. Terahertz Sensing, Imaging and Applications

    Energy Technology Data Exchange (ETDEWEB)

    Otani, C.; Hoshing, H.; Sasaki, Y.; Maki, K.; Hayashi, A. [RIKEN Advanced Science Institute, Sendai (Japan)

    2008-11-15

    Diagnosis using terahertz (THz) wave holds a great potential for various applications in various fields because of its transmittance to many soft materials with the good spatial resolution. In addition, the presence of specific spectral absorption features of crystalline materials is also important for many applications. Such features are different from material to material to material and is applicable for identifying materials inside packages that are opaque to visible light. One of the most impressive examples of such applications is the detection of illicit drugs inside envelopes. In this talk, we will present our recent topics of THz sensing, imaging and applications including this example. We will also present the cancer diagnosis, an application of the photonic crystal to high sensitivity detection, and gas spectroscopy if we have enough time. We also would like to briefly review the recent topics related to THz applications.

  12. Terahertz Sensing, Imaging and Applications

    International Nuclear Information System (INIS)

    Otani, C.; Hoshing, H.; Sasaki, Y.; Maki, K.; Hayashi, A.

    2008-01-01

    Diagnosis using terahertz (THz) wave holds a great potential for various applications in various fields because of its transmittance to many soft materials with the good spatial resolution. In addition, the presence of specific spectral absorption features of crystalline materials is also important for many applications. Such features are different from material to material to material and is applicable for identifying materials inside packages that are opaque to visible light. One of the most impressive examples of such applications is the detection of illicit drugs inside envelopes. In this talk, we will present our recent topics of THz sensing, imaging and applications including this example. We will also present the cancer diagnosis, an application of the photonic crystal to high sensitivity detection, and gas spectroscopy if we have enough time. We also would like to briefly review the recent topics related to THz applications

  13. Non-invasive identification of metal-oxalate complexes on polychrome artwork surfaces by reflection mid-infrared spectroscopy.

    Science.gov (United States)

    Monico, Letizia; Rosi, Francesca; Miliani, Costanza; Daveri, Alessia; Brunetti, Brunetto G

    2013-12-01

    In this work a reflection mid-infrared spectroscopy study of twelve metal-oxalate complexes, of interest in art conservation science as alteration compounds, was performed. Spectra of the reference materials highlighted the presence of derivative-like and/or inverted features for the fundamental vibrational modes as result of the main contribution from the surface component of the reflected light. In order to provide insights in the interpretation of theses spectral distortions, reflection spectra were compared with conventional transmission ones. The Kramers-Kronig (KK) algorithm, employed to correct for the surface reflection distortions, worked properly only for the derivative-like bands. Therefore, to pay attention to the use of this algorithm when interpreting the reflection spectra is recommended. The outcome of this investigation was exploited to discriminate among different oxalates on thirteen polychrome artworks analyzed in situ by reflection mid-infrared spectroscopy. The visualization of the νs(CO) modes (1400-1200 cm(-1)) and low wavenumber bands (below 900 cm(-1)) in the raw reflection profiles allowed Ca, Cu and Zn oxalates to be identified. Further information about the speciation of different hydration forms of calcium oxalates were obtained by using the KK transform. The work proves reflection mid-infrared spectroscopy to be a reliable and sensitive spectro-analytical method for identifying and mapping different metal-oxalate alteration compounds on the surface of artworks, thus providing conservation scientists with a non-invasive tool to obtain information on the state of conservation and causes of alteration of artworks. Copyright © 2013 Elsevier B.V. All rights reserved.

  14. An effective way to reduce water absorption to terahertz

    Science.gov (United States)

    Wu, Yaxiong; Su, Bo; He, Jingsuo; Zhang, Cong; Zhang, Hongfei; Zhang, Shengbo; Zhang, Cunlin

    2018-01-01

    Since many vibrations and rotational levels of biomolecules fall within the THz band, THz spectroscopy can be used to identify biological samples. In addition, most biomolecules need to maintain their biological activity in a liquid environment, but water as polar substance has strong absorption to the THz wave. Thus, it is difficult to detect the sample information in aqueous solution using THz wave. In order to prevent the information of biological samples were masked in the solution, many research methods were used to explore how to reduce the water absorption of terahertz. In this paper, we have developed a real-time chemical methodology through transmission Terahertz time-domain spectroscopy (THz-TDS) system. The material of Zeonor 1020r is used as substrate and cover plate, and PDMS as channel interlayer. The transmission of the empty microfluidic chip is more than 80% in the range of 0.2-2.6 THz by THz-TDS system. Then, experiments were carried out using chips, which were filled with different volumes of 1, 2- propanediol, and it has been proved that the microfluidic chip could reduce the water absorption of terahertz. Finally, in order to further explore the reduction of terahertz to water absorption, we inject different concentrations of electrolyte to the chip. The results show that with the addition of different electrolytes, terahertz transmission line has evident changes. It can be taken into account that the electrolyte has different effects about the hydrogen bonds in the aqueous solution. Some of them can promote water molecules clusters, while others destroy them. Based on the basis of microfluidic chip, the discovery of this phenomenon can provide a way that reduces water absorption of terahertz. This work has laid a solid foundation for the subsequent study in reducing water absorption of terahertz.

  15. Continuous-wave terahertz light from optical parametric oscillators

    Energy Technology Data Exchange (ETDEWEB)

    Sowade, Rosita

    2010-12-15

    Continuous-wave (cw) optical parametric oscillators (OPOs) are working horses for spectroscopy in the near and mid infrared. However, in the terahertz frequency range (0.1 to 10 THz), the pump threshold is more than 100 W due to the high absorption in nonlinear crystals and thus exceeds the power of standard cw single-frequency pump sources. In this thesis the first cw OPO capable of generating terahertz radiation is demonstrated. To overcome the high threshold, the signal wave of a primary infrared process is resonantly enhanced to serve as the pump wave for a cascaded parametric process with one wave being at the terahertz frequency level. A terahertz output power of more than two microwatts is measured and tuning is achieved from 1.3 to 1.7 THz. This terahertz source emits a narrow-band, diffraction-limited beam which remains mode-hop free over more than one hour. Such a device inhibits high potential for applications in areas like astronomy, telecommunications or high-resolution spectroscopy. (orig.)

  16. Continuous-wave terahertz light from optical parametric oscillators

    International Nuclear Information System (INIS)

    Sowade, Rosita

    2010-12-01

    Continuous-wave (cw) optical parametric oscillators (OPOs) are working horses for spectroscopy in the near and mid infrared. However, in the terahertz frequency range (0.1 to 10 THz), the pump threshold is more than 100 W due to the high absorption in nonlinear crystals and thus exceeds the power of standard cw single-frequency pump sources. In this thesis the first cw OPO capable of generating terahertz radiation is demonstrated. To overcome the high threshold, the signal wave of a primary infrared process is resonantly enhanced to serve as the pump wave for a cascaded parametric process with one wave being at the terahertz frequency level. A terahertz output power of more than two microwatts is measured and tuning is achieved from 1.3 to 1.7 THz. This terahertz source emits a narrow-band, diffraction-limited beam which remains mode-hop free over more than one hour. Such a device inhibits high potential for applications in areas like astronomy, telecommunications or high-resolution spectroscopy. (orig.)

  17. [Near infrared reflectance spectroscopy (NIRS): a novel approach to reconstructing historical changes of primary productivity in Antarctic lake].

    Science.gov (United States)

    Chen, Qian-Qian; Liu, Xiao-Dong; Liu, Wen-Qi; Jiang, Shan

    2011-10-01

    Compared with traditional chemical analysis methods, reflectance spectroscopy has the advantages of speed, minimal or no sample preparation, non-destruction, and low cost. In order to explore the potential application of spectroscopy technology in the paleolimnological study on Antarctic lakes, we took a lake sediment core in Mochou Lake at Zhongshan Station of Antarctic, and analyzed the near infrared reflectance spectroscopy (NIRS) data in the sedimentary samples. The results showed that the factor loadings of principal component analysis (PCA) displayed very similar depth-profile change pattern with the S2 index, a reliable proxy for the change in historical lake primary productivity. The correlation analysis showed that the values of PCA factor loading and S2 were correlated significantly, suggesting that it is feasible to infer paleoproductivity changes recorded in Antarctic lakes using NIRS technology. Compared to the traditional method of the trough area between 650 and 700 nm, the authors found that the PCA statistical approach was more accurate for reconstructing the change in historical lake primary productivity. The results reported here demonstrate that reflectance spectroscopy can provide a rapid method for the reconstruction of lake palaeoenviro nmental change in the remote Antarctic regions.

  18. Determining the mineral composition in Cucurbita pepo fruit using near infrared reflectance spectroscopy.

    Science.gov (United States)

    Martínez-Valdivieso, Damián; Font, Rafael; Gómez, Pedro; Blanco-Díaz, Teresa; Del Río-Celestino, Mercedes

    2014-12-01

    Efforts through conventional breeding to improve the mineral content in horticultural crops have not always been successful mainly due to the fact that standard analytical methods are both costly and time-consuming. We investigated the feasibility of applying near infrared reflectance spectroscopy (NIRS) to the estimation of essential mineral composition in the skin and flesh of summer squash fruits (Cucurbita pepo subsp. pepo) using a 200-sample set from diverse morphotypes. The coefficients of determination in the external validation (R(2) VAL) obtained for the skin and flesh of the fruit were: total mineral content, 0.84 and 0.70; P, 0.74 and 0.62; K, 0.83 and 0.67; Ca, 0.57 and 0.60; Mg, 0.78 and 0.45; Fe, 0.78 and 0.65; Cu, 0.67 and 0.66; Mn, 0.67 and 0.64; Zn, 0.80 and 0.79 and Na, 0.33 and 0.33; respectively. NIRS combined with different spectral transformations by modified partial least-squares (MPLS) regression has shown to be useful in determining the mineral composition of summer squash fruit, being a fast and low-cost analytical technique. Components such as chlorophyll, starch and lipids were used by MPLS for modelling the predicting equations. The promotion of micronutrient-rich summer squash varieties could have a significant long-term beneficial impact on the health of mineral deficient human populations. © 2014 Society of Chemical Industry.

  19. STUDY OF INK LAYER BY METHOD OF ATTENUATED TOTAL REFLECTANCE SPECTROSCOPY

    Directory of Open Access Journals (Sweden)

    D. G. Fatkhullina

    2016-05-01

    Full Text Available Subject of Research. Researchresults of thickness distribution of an ink layer smearedon a glass surface are presented. The orange ink which is used as a coloring pigment in writing instrument (highlighter is selectedasan object of study. Method. Researches were carried out by the method of attenuated total reflectance(ATR spectroscopy. The spectral setup fitted up on the basis of monochromator MDR-204 was usedin the experiment. The peculiarity of the measurement scheme is the applicationofhigh-resolution camera as a radiation detector and information storage as an images package. Researches allowed receivingexperimental data in the form of ink ATR spectra arrayfor studied areas of layer surface in a given spectral range. Main Results. The estimation of ink layer thickness was done, that gives the possibilityto visualize its distribution over the surface using three-dimensional modeling capabilities. The thickness of the ink layer is not more than 0.12 microns and arithmetic mean of the thickness is0.06 microns. The local areas are observed in an ink distribution, they have a maximum layer thickness (0.07-0.12 microns or areas with the ink thickness less then 0.03 microns. Variation of the ink layer thicknessbetween the local areas is smooth. Practical Relevance. The proposed measuring scheme, the sequence of registration and processing of experimental data can be used to studyink distribution within the thickness of a surface layer of other materials,for example, in analysis of signs performed by an ink on paper medium in order to identify them in such areas of science as forensic science andstudy of art.

  20. Suitability of faecal near-infrared reflectance spectroscopy (NIRS) predictions for estimating gross calorific value

    Energy Technology Data Exchange (ETDEWEB)

    De la Roza-Delgado, B.; Modroño, S.; Vicente, F.; Martínez-Fernández, A.; Soldado, A.

    2015-07-01

    A total of 220 faecal pig and poultry samples, collected from different experimental trials were employed with the aim to demonstrate the suitability of Near Infrared Reflectance Spectroscopy (NIRS) technology for estimation of gross calorific value on faeces as output products in energy balances studies. NIR spectra from dried and grounded faeces samples were analyzed using a Foss NIRSystem 6500 instrument, scanning over the wavelength range 400-2500 nm. Validation studies for quantitative analytical models were carried out to estimate the relevance of method performance associated to reference values to obtain an appropriate, accuracy and precision. The results for prediction of gross calorific value (GCV) of NIRS calibrations obtained for individual species showed high correlation coefficients comparing chemical analysis and NIRS predictions, ranged from 0.92 to 0.97 for poultry and pig. For external validation, the ratio between the standard error of cross validation (SECV) and the standard error of prediction (SEP) varied between 0.73 and 0.86 for poultry and pig respectively, indicating a sufficiently precision of calibrations. In addition a global model to estimate GCV in both species was developed and externally validated. It showed correlation coefficients of 0.99 for calibration, 0.98 for cross-validation and 0.97 for external validation. Finally, relative uncertainty was calculated for NIRS developed prediction models with the final value when applying individual NIRS species model of 1.3% and 1.5% for NIRS global prediction. This study suggests that NIRS is a suitable and accurate method for the determination of GCV in faeces, decreasing cost, timeless and for convenient handling of unpleasant samples.. (Author)

  1. Electronic and optical properties of Fe, Pd, and Ti studied by reflection electron energy loss spectroscopy

    International Nuclear Information System (INIS)

    Tahir, Dahlang; Kraaer, Jens; Tougaard, Sven

    2014-01-01

    We have studied the electronic and optical properties of Fe, Pd, and Ti by reflection electron energy-loss spectroscopy (REELS). REELS spectra recorded for primary energies in the range from 300 eV to 10 keV were corrected for multiple inelastically scattered electrons to determine the effective inelastic-scattering cross section. The dielectric functions and optical properties were determined by comparing the experimental inelastic-electron scattering cross section with a simulated cross section calculated within the semi-classical dielectric response model in which the only input is Im(−1/ε) by using the QUEELS-ε(k,ω)-REELS software package. The complex dielectric functions ε(k,ω), in the 0–100 eV energy range, for Fe, Pd, and Ti were determined from the derived Im(−1/ε) by Kramers-Kronig transformation and then the refractive index n and extinction coefficient k. The validity of the applied model was previously tested and found to give consistent results when applied to REELS spectra at energies between 300 and 1000 eV taken at widely different experimental geometries. In the present paper, we provide, for the first time, a further test on its validity and find that the model also gives consistent results when applied to REELS spectra in the full range of primary electron energies from 300 eV to 10000 eV. This gives confidence in the validity of the applied method.

  2. Characterization and quantitation of aprepitant drug substance polymorphs by attenuated total reflectance fourier transform infrared spectroscopy.

    Science.gov (United States)

    Helmy, Roy; Zhou, George X; Chen, Yadan W; Crocker, Louis; Wang, Tao; Wenslow, Robert M; Vailaya, Anant

    2003-02-01

    In this study, we report the use of attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FT-IR) for the identification and quantitation of two polymorphs of Aprepitant, a substance P antagonist for chemotherapy-induced emesis. Mixtures of the polymorph pair were prepared by weight and ATR-FT-IR spectra of the powdered samples were obtained over the wavelength range of 700-1500 cm(-1). Significant spectral differences between the two polymorphs at 1140 cm(-1) show that ATR-FT-IR can provide definitive identification of the polymorphs. To investigate the feasibility of ATR-FT-IR for quantitation of polymorphic forms of Aprepitant, a calibration plot was constructed with known mixtures of the two polymorphs by plotting the peak ratio of the second derivative of absorbance spectra against the weight percent of form II in the polymorphic mixture. Using this novel approach, 3 wt % of one crystal form could be detected in mixtures of the two polymorphs. The accuracy of ATR-FT-IR in determining polymorph purity of the drug substance was tested by comparing the results with those obtained by X-ray powder diffractometry (XRPD). Indeed, polymorphic purity results obtained by ATR-FT-IR were found to be in good agreement with the predictions made by XRPD and compared favorably with actual values in the known mixtures. The present study clearly demonstrates the potential of ATR-FT-IR as a quick, easy, and inexpensive alternative to XRPD for the determination of polymorphic identity and purity of solid drug substances. The technique is ideally suited for polymorph analysis, because it is precise, accurate, and requires minimal sample preparation.

  3. Terahertz radiation mixer

    Science.gov (United States)

    Wanke, Michael C [Albuquerque, NM; Allen, S James [Santa Barbara, CA; Lee, Mark [Albuquerque, NM

    2008-05-20

    A terahertz radiation mixer comprises a heterodyned field-effect transistor (FET) having a high electron mobility heterostructure that provides a gatable two-dimensional electron gas in the channel region of the FET. The mixer can operate in either a broadband pinch-off mode or a narrowband resonant plasmon mode by changing a grating gate bias of the FET. The mixer can beat an RF signal frequency against a local oscillator frequency to generate an intermediate frequency difference signal in the microwave region. The mixer can have a low local oscillator power requirement and a large intermediate frequency bandwidth. The terahertz radiation mixer is particularly useful for terahertz applications requiring high resolution.

  4. Charge transport in silicon nanocrystal superlattices in the terahertz regime

    Czech Academy of Sciences Publication Activity Database

    Němec, Hynek; Zajac, Vít; Kužel, Petr; Malý, P.; Gutsch, S.; Hiller, D.; Zacharias, M.

    2015-01-01

    Roč. 91, č. 19 (2015), "195443-1"-"195443-10" ISSN 1098-0121 R&D Projects: GA ČR GA13-12386S Institutional support: RVO:68378271 Keywords : silicon nanocrystals * charge transport * terahertz spectroscopy Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.736, year: 2014

  5. Time Resolved Broadband Terahertz Relaxation Dynamics of Electron in Water

    DEFF Research Database (Denmark)

    Wang, Tianwu; Iwaszczuk, Krzysztof; Cooke, David G.

    We investigated the transient response of the solvated electron in water ejected by photodetachment from potassium ferrocyanide using time resolved terahertz spectroscopy (TSTS). Ultrabroadband THz transients are generated and detected by a two-color femtosecond-induced air plasma and air biased...

  6. Terahertz heterodyne technology for astronomy and planetary science

    NARCIS (Netherlands)

    Wild, Wolfgang

    2007-01-01

    Heterodyne detection techniques play an important role in high-resolution spectroscopy in astronomy and planetary science. In particular, heterodyne technology in the Terahertz range has rapidly evolved in recent years. Cryogenically cooled receivers approaching quantum-limited sensitivity have been

  7. Wideband Integrated Lens Antennas for Terahertz Deep Space Investigation

    NARCIS (Netherlands)

    Yurduseven, O.

    2016-01-01

    The Terahertz (THz) band is the portion of the spectrum that covers a frequency range from 300 GHz to 3 THz. The potential of this band has been proven for numerous type of applications including medical imaging, non-destructive testing, space observation, spectroscopy and security screening, thanks

  8. EDITORIAL: Photonic terahertz technology

    Science.gov (United States)

    Lisauskas, Alvydas; Löffler, Torsten; Roskos, Hartmut G.

    2005-07-01

    In recent years, when reading newspapers and journals or watching TV, one has been able to find feature presentations dealing with the prospects of terahertz (THz) technology and its potential impact on market applications. THz technology aims to fill the THz gap in the electro-magnetic spectrum in order to make the THz frequency regime, which spans the two orders of magnitude from 100 GHz to 10 THz, accessible for applications. From the lower-frequency side, electronics keeps pushing upwards, while photonic approaches gradually improve our technological options at higher frequencies. The popular interest reflects the considerable advances in research in the THz field, and it is mainly advances in the photonic branch, with the highlight being the development of the THz quantum cascade laser, which in recent years have caught the imagination of the public, and of potential users and investors. This special issue of Semiconductor Science and Technology provides an overview of key scientific developments which currently represent the cutting edge of THz photonic technology. In order to be clear about the implications, we should define exactly what we mean by 'THz photonic technology', or synonymously 'THz photonics'. It is characterized by the way in which THz radiation (or a guided THz wave) is generated, namely by the use of lasers. This may be done in one of two fundamentally different schemes: (i) by laser action in the terahertz frequency range itself (THz lasers), or (ii) by down-conversion processes (photomixing) involving the radiation of lasers which operate in the visible, near-infrared or infrared spectral ranges, either in pulsed or continuous-wave mode. The field of THz photonics has grown so considerably that it is out of the question to cover all its aspects in a single special issue of a journal. We have elected, instead, to focus our attention on two types of development with a potentially strong impact on the THz field: first, on significant advances

  9. Terahertz sensing of highly absorptive water-methanol mixtures with multiple resonances in metamaterials.

    Science.gov (United States)

    Chen, Min; Singh, Leena; Xu, Ningning; Singh, Ranjan; Zhang, Weili; Xie, Lijuan

    2017-06-26

    Terahertz sensing of highly absorptive aqueous solutions remains challenging due to strong absorption of water in the terahertz regime. Here, we experimentally demonstrate a cost-effective metamaterial-based sensor integrated with terahertz time-domain spectroscopy for highly absorptive water-methanol mixture sensing. This metamaterial has simple asymmetric wire structures that support multiple resonances including a fundamental Fano resonance and higher order dipolar resonance in the terahertz regime. Both the resonance modes have strong intensity in the transmission spectra which we exploit for detection of the highly absorptive water-methanol mixtures. The experimentally characterized sensitivities of the Fano and dipole resonances for the water-methanol mixtures are found to be 160 and 305 GHz/RIU, respectively. This method provides a robust route for metamaterial-assisted terahertz sensing of highly absorptive chemical and biochemical materials with multiple resonances and high accuracy.

  10. Non-invasive identification of organic materials in historical stringed musical instruments by reflection infrared spectroscopy: a methodological approach.

    Science.gov (United States)

    Invernizzi, Claudia; Daveri, Alessia; Vagnini, Manuela; Malagodi, Marco

    2017-05-01

    The analysis of historical musical instruments is becoming more relevant and the interest is increasingly moving toward the non-invasive reflection FTIR spectroscopy, especially for the analysis of varnishes. In this work, a specific infrared reflectance spectral library of organic compounds was created with the aim of identifying musical instrument materials in a totally non-invasive way. The analyses were carried out on pure organic compounds, as bulk samples and laboratory wooden models, to evaluate the diagnostic reflection mid-infrared (MIR) bands of proteins, polysaccharides, lipids, and resins by comparing reflection spectra before and after the KK correction. This methodological approach was applied to real case studies represented by four Stradivari violins and a Neapolitan mandolin.

  11. Disposable attenuated total reflection-infrared crystals from silicon wafer: a versatile approach to surface infrared spectroscopy.

    Science.gov (United States)

    Karabudak, Engin; Kas, Recep; Ogieglo, Wojciech; Rafieian, Damon; Schlautmann, Stefan; Lammertink, R G H; Gardeniers, Han J G E; Mul, Guido

    2013-01-02

    Attenuated total reflection-infrared (ATR-IR) spectroscopy is increasingly used to characterize solids and liquids as well as (catalytic) chemical conversion. Here we demonstrate that a piece of silicon wafer cut by a dicing machine or cleaved manually can be used as disposable internal reflection element (IRE) without the need for polishing and laborious edge preparation. Technical aspects, fundamental differences, and pros and cons of these novel disposable IREs and commercial IREs are discussed. The use of a crystal (the Si wafer) in a disposable manner enables simultaneous preparation and analysis of substrates and application of ATR spectroscopy in high temperature processes that may lead to irreversible interaction between the crystal and the substrate. As representative application examples, the disposable IREs were used to study high temperature thermal decomposition and chemical changes of polyvinyl alcohol (PVA) in a titania (TiO(2)) matrix and assemblies of 65-450 nm thick polystyrene (PS) films.

  12. THE STUDY OF CLINOPTILOLITE MODIFIED WITH3d METALS HALIDES BY IR AND DIFFUSE REFLECTANCE SPECTROSCOPY

    Directory of Open Access Journals (Sweden)

    T. L. Rakitskaya

    2015-11-01

    Full Text Available The results of investigation of natural clinoptilolite (N-CLI and that modified with 3d metal halides (MeCl2/N-CLI, where Me are Cu, Co, and Mn by IR and diffuse reflectance spectroscopy are summarized. A band at 3437 cm-1 assigned to stretching vibrations of hydroxyl groups (nOH is found in the IR spectrum of the N-CLI sample. A location of the band was practically the same as for all above MeCl2/N-CLI samples. A band of middle intensity at 1638 cm-1 in the range of deformation vibrations of zeolite water observed in the IR spectrum of N-CLI slightly displays to lower frequencies in the case of the modified samples. An intensive wide band of a complex shape in the range from 1250 to 980 cm-1 assigned to Si–O–Si and Si–O–Al vibrations appears in IR spectra of all samples. A doublet band of middle intensity at 797 and 778 cm-1 is assigned to external symmetric stretching T-O vibrations and a band at 606 cm-1-to vibrations of a double ring. A location of the above bands is the same for all listed samples but their intensity is higher for MnCl2/N-CLI and CoCl2/N-CLI samples. After the reaction with ozone, significant changes in the IR spectra are observed only for MnCl2/N-CLI. They are due to MnO2 formation on the clinoptilolite surface resulting in a high frequency displacement of some bands. Based on UV-vi spectroscopy results, it is reasonable to make conclusions about the coordination and valence state of a central atom in the MeCl2/N-CLI samples under study. A location of charge transfer bands for these samples only slightly differs from that for N-CLI however the intensity of such bands increases for the MeCl2/N-CLI samples. The UV-vis spectrum of MnCl2/N-CLI changes after the reaction with ozone: the appearance of new bands of  charge transfer at 363 and 354 nm and also the two-fold increase in intensity of a charge transfer band at 272 nm in comparison with those of N-CLI and MnCl2/N-CLI are the evidence of change in both the

  13. Direct characterization of the energy level alignments and molecular components in an organic hetero-junction by integrated photoemission spectroscopy and reflection electron energy loss spectroscopy analysis.

    Science.gov (United States)

    Yun, Dong-Jin; Shin, Weon-Ho; Bulliard, Xavier; Park, Jong Hwan; Kim, Seyun; Chung, Jae Gwan; Kim, Yongsu; Heo, Sung; Kim, Seong Heon

    2016-08-26

    A novel, direct method for the characterization of the energy level alignments at bulk-heterojunction (BHJ)/electrode interfaces on the basis of electronic spectroscopy measurements is proposed. The home-made in situ photoemission system is used to perform x-ray/ultraviolet photoemission spectroscopy (XPS/UPS), reflection electron energy loss spectroscopy (REELS) and inverse photoemission spectroscopy of organic-semiconductors (OSCs) deposited onto a Au substrate. Through this analysis system, we are able to obtain the electronic structures of a boron subphthalocyanine chloride:fullerene (SubPC:C60) BHJ and those of the separate OSC/electrode structures (SubPC/Au and C60/Au). Morphology and chemical composition analyses confirm that the original SubPC and C60 electronic structures remain unchanged in the electrodes prepared. Using this technique, we ascertain that the position and area of the nearest peak to the Fermi energy (EF = 0 eV) in the UPS (REELS) spectra of SubPC:C60 BHJ provide information on the highest occupied molecular orbital level (optical band gap) and combination ratio of the materials, respectively. Thus, extracting the adjusted spectrum from the corresponding SubPC:C60 BHJ UPS (REELS) spectrum reveals its electronic structure, equivalent to that of the C60 materials. This novel analytical approach allows complete energy-level determination for each combination ratio by separating its electronic structure information from the BHJ spectrum.

  14. Synchrotron Radiation Total Reflection X-ray Fluorescence Spectroscopy for Microcontamination Analysis on Silicon Wafer Surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Takaura, Norikatsu

    1997-10-01

    As dimensions in state-of-the-art CMOS devices shrink to less than 0.1 pm, even low levels of impurities on wafer surfaces can cause device degradation. Conventionally, metal contamination on wafer surfaces is measured using Total Reflection X-Ray Fluorescence Spectroscopy (TXRF). However, commercially available TXRF systems do not have the necessary sensitivity for measuring the lower levels of contamination required to develop new CMOS technologies. In an attempt to improve the sensitivity of TXRF, this research investigates Synchrotron Radiation TXRF (SR TXRF). The advantages of SR TXRF over conventional TXRF are higher incident photon flux, energy tunability, and linear polarization. We made use of these advantages to develop an optimized SR TXRF system at the Stanford Synchrotron Radiation Laboratory (SSRL). The results of measurements show that the Minimum Detection Limits (MDLs) of SR TXRF for 3-d transition metals are typically at a level-of 3x10{sup 8} atoms/cm{sup 2}, which is better than conventional TXRF by about a factor of 20. However, to use our SR TXRF system for practical applications, it was necessary to modify a commercially available Si (Li) detector which generates parasitic fluorescence signals. With the modified detector, we could achieve true MDLs of 3x10{sup 8} atoms/cm{sup 2} for 3-d transition metals. In addition, the analysis of Al on Si wafers is described. Al analysis is difficult because strong Si signals overlap the Al signals. In this work, the Si signals are greatly reduced by tuning the incident beam energy below the Si K edge. The results of our measurements show that the sensitivity for Al is limited by x-ray Raman scattering. Furthermore, we show the results of theoretical modeling of SR TXRF backgrounds consisting of the bremsstrahlung generated by photoelectrons, Compton scattering, and Raman scattering. To model these backgrounds, we extended conventional theoretical models by taking into account several aspects particular

  15. Terahertz Radome Inspection

    Directory of Open Access Journals (Sweden)

    Fabian Friederich

    2018-01-01

    Full Text Available Radomes protecting sensitive radar, navigational, and communications equipment of, e.g., aircraft, are strongly exposed to the environment and have to withstand harsh weather conditions and potential impacts. Besides their significance to the structural integrity of the radomes, it is often crucial to optimize the composite structures for best possible radio performance. Hence, there exists a significant interest in non-destructive testing techniques, which can be used for defect inspection of radomes in field use as well as for quality inspection during the manufacturing process. Contactless millimeter-wave and terahertz imaging techniques provide millimeter resolution and have the potential to address both application scenarios. We report on our development of a three-dimensional (3D terahertz imaging system for radome inspection during industrial manufacturing processes. The system was designed for operation within a machining center for radome manufacturing. It simultaneously gathers terahertz depth information in adjacent frequency ranges, from 70 to 110 GHz and from 110 to 170 GHz by combining two frequency modulated continuous-wave terahertz sensing units into a single measurement device. Results from spiraliform image acquisition of a radome test sample demonstrate the successful integration of the measurement system.

  16. Surface characterization of selected polymer thin films by total-reflection x-ray fluorescence spectroscopy and x-ray reflectivity

    International Nuclear Information System (INIS)

    Innis, Vallerie Ann A.

    2006-01-01

    Development of available x-ray characterizations tools for grazing incidence techniques was done to be able to probe nano-size thin films. Alignment of a Philips x-ray powder diffractometer was improved to let it perform as an x-ray reflectometer. X-ray reflectometry was coupled with total-reflection x-ray fluorescence spectroscopy. Evaluation of the performance of this grazing incidence techniques was done by preparing polymer thin films of carboxymethylcellulose, carrageenan and polyvinylpyrrolidone (PVP). The thickness of the films were varied by varying the process parameters such as concentration, spin speed and spin time. Angle-dispersive total-reflection x-ray fluorescence spectroscopy profiles of three films showed film formation only in carrageenan and PVP. For both carrageenan and PVP, an increase in concentration yielded a corresponding increase in intensity of the fluorescent or scattered peaks. XRR profiles of carrageenan thin films yielded a mean value for the critical angle close to quartz substrate. Thickness measurements of the prepared carrageenan thin films showed that concentration was the main determinant for final film thickness over the other process parameters. Sulfur fluorescent intensity derived from the TXRF measurement showed a linear relationship with the measured thickness by XRR. For PVP, measured critical angle is lower than quartz. Poor adhesion of the polymer onto the substrate yielded a limited number of thickness measurements made from the XRR profiles. (Author)

  17. Exploiting Optical Contrasts for Cervical Precancer Diagnosis via Diffuse Reflectance Spectroscopy

    Science.gov (United States)

    Chang, Vivide Tuan-Chyan

    collagen without altering the amount of collagen present. Further work would be required to elucidate the exact sources of scattering contrast observed. Common confounding variables that limit the accuracy and clinical acceptability of optical spectroscopic systems are calibration requirements and variable probe-tissue contact pressures. Our results suggest that using a real-time self-calibration channel, as opposed to conventional post-experiment diffuse reflectance standard calibration measurements, significantly improved data integrity for the extraction of scattering contrast. Extracted [total Hb] and scattering were also significantly associated with applied contact probe pressure in colposcopically normal sites. Hence, future contact probe spectroscopy or imaging systems should incorporate a self-calibration channel and ensure spectral acquisition at a consistent contact pressure to collect reliable data with enhanced absorption and scattering contrasts. Another method to enhance optical contrast is to selectively interrogate different depths in the dysplastic cervix. For instance, scattering has been shown to increase in the epithelium (increase in nuclear-to-cytoplasmic ratio) while decrease in the stroma (re-organization of the extra-cellular matrix and changes in of collagen fiber cross-links). A fiber-optic probe with 45° illumination and collection fibers with a separation distance of 330 μm was designed and constructed to selectively interrogate the cervical epithelium. Mean extraction errors from liquid phantoms with optical properties mimicking the cervical epithelium for μa and μs' were 11.3 % and 12.7 %, respectively. Diffuse reflectance spectra from 9 sites in four loop electrosurgical excision procedure (LEEP) patients were analyzed. Preliminary data demonstrate the utility of the oblique fiber geometry in extracting scattering contrast in the cervical epithelium. Further work is needed to study the systematic error in optical property extraction and

  18. Terahertz thickness determination with interferometric vibration correction for industrial applications.

    Science.gov (United States)

    Pfeiffer, Tobias; Weber, Stefan; Klier, Jens; Bachtler, Sebastian; Molter, Daniel; Jonuscheit, Joachim; Von Freymann, Georg

    2018-05-14

    In many industrial fields, like automotive and painting industry, the thickness of thin layers is a crucial parameter for quality control. Hence, the demand for thickness measurement techniques continuously grows. In particular, non-destructive and contact-free terahertz techniques access a wide range of thickness determination applications. However, terahertz time-domain spectroscopy based systems perform the measurement in a sampling manner, requiring fixed distances between measurement head and sample. In harsh industrial environments vibrations of sample and measurement head distort the time-base and decrease measurement accuracy. We present an interferometer-based vibration correction for terahertz time-domain measurements, able to reduce thickness distortion by one order of magnitude for vibrations with frequencies up to 100 Hz and amplitudes up to 100 µm. We further verify the experimental results by numerical calculations and find very good agreement.

  19. Reflections

    Directory of Open Access Journals (Sweden)

    Joanne Embree

    2001-01-01

    Full Text Available Ideally, editorials are written one to two months before publication in the Journal. It was my turn to write this one. I had planned to write the first draft the evening after my clinic on Tuesday, September 11. It didn't get done that night or during the next week. Somehow, the topic that I had originally chosen just didn't seem that important anymore as I, along my friends and colleagues, reflected on the changes that the events of that day were likely to have on our lives.

  20. Classification of Fusarium-Infected Korean Hulled Barley Using Near-Infrared Reflectance Spectroscopy and Partial Least Squares Discriminant Analysis

    Directory of Open Access Journals (Sweden)

    Jongguk Lim

    2017-09-01

    Full Text Available The purpose of this study is to use near-infrared reflectance (NIR spectroscopy equipment to nondestructively and rapidly discriminate Fusarium-infected hulled barley. Both normal hulled barley and Fusarium-infected hulled barley were scanned by using a NIR spectrometer with a wavelength range of 1175 to 2170 nm. Multiple mathematical pretreatments were applied to the reflectance spectra obtained for Fusarium discrimination and the multivariate analysis method of partial least squares discriminant analysis (PLS-DA was used for discriminant prediction. The PLS-DA prediction model developed by applying the second-order derivative pretreatment to the reflectance spectra obtained from the side of hulled barley without crease achieved 100% accuracy in discriminating the normal hulled barley and the Fusarium-infected hulled barley. These results demonstrated the feasibility of rapid discrimination of the Fusarium-infected hulled barley by combining multivariate analysis with the NIR spectroscopic technique, which is utilized as a nondestructive detection method.

  1. Hollow optical-fiber based infrared spectroscopy for measurement of blood glucose level by using multi-reflection prism.

    Science.gov (United States)

    Kino, Saiko; Omori, Suguru; Katagiri, Takashi; Matsuura, Yuji

    2016-02-01

    A mid-infrared attenuated total reflection (ATR) spectroscopy system employing hollow optical fibers and a trapezoidal multi-reflection ATR prism has been developed to measure blood glucose levels. Using a multi-reflection prism brought about higher sensitivity, and the flat and wide contact surface of the prism resulted in higher measurement reproducibility. An analysis of in vivo measurements of human inner lip mucosa revealed clear signatures of glucose in the difference spectra between ones taken during the fasting state and ones taken after ingestion of glucose solutions. A calibration plot based on the absorption peak at 1155 cm(-1) that originates from the pyranose ring structure of glucose gave measurement errors less than 20%.

  2. Tissue differentiation by diffuse reflectance spectroscopy for automated oral and maxillofacial laser surgery: ex vivo pilot study

    Science.gov (United States)

    Zam, Azhar; Stelzle, Florian; Tangermann-Gerk, Katja; Adler, Werner; Nkenke, Emeka; Schmidt, Michael; Douplik, Alexandre

    2010-02-01

    Remote laser surgery lacks of haptic feedback during the laser ablation of tissue. Hence, there is a risk of iatrogenic damage or destruction of anatomical structures like nerves or salivary glands. Diffuse reflectance spectroscopy provides a straightforward and simple approach for optical tissue differentiation. We measured diffuse reflectance from seven various tissue types ex vivo. We applied Linear Discriminant Analysis (LDA) to differentiate the seven tissue types and computed the area under the ROC curve (AUC). Special emphasis was taken on the identification of nerves and salivary glands as the most crucial tissue for maxillofacial surgery. The results show a promise for differentiating tissues as guidance for oral and maxillofacial laser surgery by means of diffuse reflectance.

  3. Enantiomeric switching of chiral metamaterial for terahertz polarization modulation employing vertically deformable MEMS spirals

    Science.gov (United States)

    Kan, Tetsuo; Isozaki, Akihiro; Kanda, Natsuki; Nemoto, Natsuki; Konishi, Kuniaki; Takahashi, Hidetoshi; Kuwata-Gonokami, Makoto; Matsumoto, Kiyoshi; Shimoyama, Isao

    2015-10-01

    Active modulation of the polarization states of terahertz light is indispensable for polarization-sensitive spectroscopy, having important applications such as non-contact Hall measurements, vibrational circular dichroism measurements and anisotropy imaging. In the terahertz region, the lack of a polarization modulator similar to a photoelastic modulator in the visible range hampers expansion of such spectroscopy. A terahertz chiral metamaterial has a huge optical activity unavailable in nature; nevertheless, its modulation is still challenging. Here we demonstrate a handedness-switchable chiral metamaterial for polarization modulation employing vertically deformable Micro Electro Mechanical Systems. Vertical deformation of a planar spiral by a pneumatic force creates a three-dimensional spiral. Enantiomeric switching is realized by selecting the deformation direction, where the polarity of the optical activity is altered while maintaining the spectral shape. A polarization rotation as high as 28° is experimentally observed, thus providing a practical and compact polarization modulator for the terahertz range.

  4. Terahertz identification and quantification of penicillamine enantiomers

    International Nuclear Information System (INIS)

    Ji Te; Zhao Hongwei; Chen Min; Xiao Tiqiao; Han Pengyu

    2013-01-01

    Identification and characterization of L-, D- and DL- penicillamine were demonstrated by Terahertz time-domain spectroscopy (THz-TDS). To understand the physical origins of the low frequency resonant modes, the density functional theory (DFT) was adopted for theoretical calculation. It was found that the collective THz frequency motions were decided by the intramolecular and intermolecular hydrogen bond interactions. Moreover, the quantification of penicillamine enantiomers mixture was demonstrated by a THz spectra fitting method with a relative error of less than 3.5%. This technique can be a valuable tool for the discrimination and quantification of chiral drugs in pharmaceutical industry. (authors)

  5. Semiconductor saturable absorbers for ultrafast terahertz signals

    DEFF Research Database (Denmark)

    Hoffmann, Matthias C.; Turchinovich, Dmitry

    2010-01-01

    states, due to conduction band onparabolicity and scattering into satellite valleys in strong THz fields. Saturable absorber parameters, such as linear and nonsaturable transmission, and saturation fluence, are extracted by fits to a classic saturable absorber model. Further, we observe THz pulse......We demonstrate saturable absorber behavior of n-type semiconductors GaAs, GaP, and Ge in the terahertz THz frequency range at room temperature using nonlinear THz spectroscopy. The saturation mechanism is based on a decrease in electron conductivity of semiconductors at high electron momentum...

  6. Diffuse Reflectance Spectroscopy of Hidden Objects, Part I: Interpretation of the Reflection-Absorption-Scattering Fractions in Near-Infrared (NIR) Spectra of Polyethylene Films.

    Science.gov (United States)

    Pomerantsev, Alexey L; Rodionova, Oxana Ye; Skvortsov, Alexej N

    2017-08-01

    Investigation of a sample covered by an interfering layer is required in many fields, e.g., for process control, biochemical analysis, and many other applications. This study is based on the analysis of spectra collected by near-infrared (NIR) diffuse reflectance spectroscopy. Each spectrum is a composition of a useful, target spectrum and a spectrum of an interfering layer. To recover the target spectrum, we suggest using a new phenomenological approach, which employs the multivariate curve resolution (MCR) method. In general terms, the problem is very complex. We start with a specific problem of analyzing a system, which consists of several layers of polyethylene (PE) film and underlayer samples with known spectral properties. To separate information originating from PE layers and the target, we modify the system versus both the number of the PE layers as well as the reflectance properties of the target sample. We consider that the interfering spectrum of the layer can be modeled using three components, which can be tentatively called transmission, absorption, and scattering contributions. The novelty of our approach is that we do not remove the reflectance and scattering effects from the spectra, but study them in detail aiming to use this information to recover the target spectrum.

  7. Phase-locking to a free-space terahertz comb for metrological-grade terahertz lasers.

    Science.gov (United States)

    Consolino, L; Taschin, A; Bartolini, P; Bartalini, S; Cancio, P; Tredicucci, A; Beere, H E; Ritchie, D A; Torre, R; Vitiello, M S; De Natale, P

    2012-01-01

    Optical frequency comb synthesizers have represented a revolutionary approach to frequency metrology, providing a grid of frequency references for any laser emitting within their spectral coverage. Extending the metrological features of optical frequency comb synthesizers to the terahertz domain would be a major breakthrough, due to the widespread range of accessible strategic applications and the availability of stable, high-power and widely tunable sources such as quantum cascade lasers. Here we demonstrate phase-locking of a 2.5 THz quantum cascade laser to a free-space comb, generated in a LiNbO(3) waveguide and covering the 0.1-6 THz frequency range. We show that even a small fraction (quantum cascade laser is sufficient to generate a beat note suitable for phase-locking to the comb, paving the way to novel metrological-grade terahertz applications, including high-resolution spectroscopy, manipulation of cold molecules, astronomy and telecommunications.

  8. Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Hellman, Hal

    1968-01-01

    This booklet discusses spectroscopy, the study of absorption of radiation by matter, including X-ray, gamma-ray, microwave, mass spectroscopy, as well as others. Spectroscopy has produced more fundamental information to the study of the detailed structure of matter than any other tools.

  9. Diffuse reflectance spectroscopy for optical nerve identification. Preliminary ex vivo results for feedback controlled oral and maxillofacial laser surgery

    Science.gov (United States)

    Stelzle, Florian; Zam, Azhar; Adler, Werner; Douplik, Alexandre; Tangermann-Gerk, Katja; Nkenke, Emeka; Neukam, Friedrich Wilhelm; Schmidt, Michael

    Objective: Laser surgery has many advantages. However, due to a lack of haptic feedback it is accompanied by the risk of iatrogenic nerve damage. The aim of this study was to evaluate the possibilities of optical nerve identification by diffuse reflectance spectroscopy to set the base for a feedback control system to enhance nerve preservation in oral and maxillofacial laser surgery. Materials and Methods: Diffuse reflectance spectra of nerve tissue, skin, mucosa, fat tissue, muscle, cartilage and bone (15120 spectra) of ex vivo pig heads were acquired in the wavelength range of 350-650 nm. Tissue differentiation was performed by principal components analysis (PCA) followed by linear discriminant analysis (LDA). Specificity and sensitivity were calculated by receiver operating characteristic (ROC) analysis and the area under curve (AUC). Results: Nerve tissue could correctly be identified and differed from skin, mucosa, fat tissue, muscle, cartilage and bone in more than 90% of the cases (AUC results) with a specificity of over 78% and a sensitivity of more than 86%. Conclusion: Nerve tissue can be identified by diffuse reflectance spectroscopy with high precision and reliability. The results may set the base for a feedback system to prevent iatrogenic nerve damage performing oral and maxillofacial laser surgery.

  10. Spectroscopy

    CERN Document Server

    Walker, S

    1976-01-01

    The three volumes of Spectroscopy constitute the one comprehensive text available on the principles, practice and applications of spectroscopy. By giving full accounts of those spectroscopic techniques only recently introduced into student courses - such as Mössbauer spectroscopy and photoelectron spectroscopy - in addition to those techniques long recognised as being essential in chemistry teaching - sucha as e.s.r. and infrared spectroscopy - the book caters for the complete requirements of undergraduate students and at the same time provides a sound introduction to special topics for graduate students.

  11. Carbon dioxide adsorption on a ZnO(101[combining macron]0) substrate studied by infrared reflection absorption spectroscopy.

    Science.gov (United States)

    Buchholz, Maria; Weidler, Peter G; Bebensee, Fabian; Nefedov, Alexei; Wöll, Christof

    2014-01-28

    The adsorption of carbon dioxide on the mixed-terminated ZnO(101[combining macron]0) surface of a bulk single crystal was studied by UHV Infrared Reflection Absorption Spectroscopy (IRRAS). In contrast to metals, the classic surface selection rule for IRRAS does not apply to bulk oxide crystals, and hence vibrational bands can also be observed for s-polarized light. Although this fact substantially complicates data interpretation, a careful analysis allows for a direct determination of the adsorbate geometry. Here, we demonstrate the huge potential of IR-spectroscopy for investigations on oxide single crystal surfaces by considering all three components of the incident polarized light separately. We find that the tridentate (surface) carbonate is aligned along the [0001] direction. A comparison to data reported previously for CO2 adsorbed on the surfaces of ZnO nanoparticles provides important insight into the role of defects in the surface chemistry of powder particles.

  12. Direct determination of lycopene content in tomatoes (Lycopersicon esculentum) by attenuated total reflectance infrared spectroscopy and multivariate analysis.

    Science.gov (United States)

    Halim, Yuwana; Schwartz, Steven J; Francis, David; Baldauf, Nathan A; Rodriguez-Saona, Luis E

    2006-01-01

    Lycopene is a potent antioxidant that has been shown to play critical roles in disease prevention. Efficient assays for detection and quantification of lycopene are desirable as alternatives to time- and labor-intensive methods. Attenuated total reflectance infrared (ATR-IR) spectroscopy was used for quantification of lycopene in tomato varieties. Calibration models were developed by partial least-squares regression (PLSR) using quantitative measures of lycopene concentration from liquid chromatography as reference method. IR spectra showed a distinct marker band at 957 cm(-1) for trans Carbon-Hydrogen (CH) deformation vibration of lycopene. PLSR models predicted the lycopene content accurately and reproducibly with a correlation coefficient (sigma) of 0.96 and standard error of cross-validation ATR-IR spectroscopy allowed for rapid, simple, and accurate determination of lycopene in tomatoes with minimal sample preparation. Results suggest that the ATR-IR method is applicable for high-throughput quantitative analysis and screening for lycopene in tomatoes.

  13. Prediction of water content in game trophies by near infrared reflectance spectroscopy

    Czech Academy of Sciences Publication Activity Database

    Kamler, Jiří; Dvořák, J.

    2007-01-01

    Roč. 15, č. 6 (2007), s. 401-404 ISSN 0967-0335 R&D Projects: GA ČR GP206/03/P134 Institutional research plan: CEZ:AV0Z60930519 Keywords : bone * NIR spectroscopy * roe deer * moisture Subject RIV: GK - Forestry Impact factor: 1.218, year: 2007

  14. Invited Article: Narrowband terahertz bandpass filters employing stacked bilayer metasurface antireflection structures

    Science.gov (United States)

    Chang, Chun-Chieh; Huang, Li; Nogan, John; Chen, Hou-Tong

    2018-05-01

    We experimentally demonstrate high-performance narrowband terahertz (THz) bandpass filters through cascading multiple bilayer metasurface antireflection structures. Each bilayer metasurface, consisting of a square array of silicon pillars with a self-aligned top gold resonator-array and a complementary bottom gold slot-array, enables near-zero reflection and simultaneously close-to-unity single-band transmission at designed operational frequencies in the THz spectral region. The THz bandpass filters based on stacked bilayer metasurfaces allow a fairly narrow, high-transmission passband, and a fast roll-off to an extremely clean background outside the passband, thereby providing superior bandpass performance. The demonstrated scheme of narrowband THz bandpass filtering is of great importance for a variety of applications where spectrally clean, high THz transmission over a narrow bandwidth is desired, such as THz spectroscopy and imaging, molecular detection and monitoring, security screening, and THz wireless communications.

  15. Nb{sub 3}Al thin film deposition for low-noise terahertz electronics

    Energy Technology Data Exchange (ETDEWEB)

    Dochev, D; Pavolotsky, A B; Belitsky, V; Olofsson, H [Group for Advanced Receiver Development and Onsala Space Observatory, Department of Radio- and Space Science, Chalmers University of Technology, SE 412 96 Gothenburg (Sweden)], E-mail: dimitar.dochev@chalmers.se

    2008-02-01

    Higher energy gap superconducting materials were always interesting for low-noise mixer applications such as superconductor-insulator-superconductor tunnel junctions (SIS) and hot-electron bolometer (HEB) used in sub-millimeter and terahertz parts of electro-magnetic spectrum. Here, we report a novel approach for producing Nb{sub 3}Al thin film by co-sputtering from two confocally arranged Nb and Al dc-magnetrons onto substrate heated up to 830 deg. C. Characterization of the deposited films revealed presence of the A15 phase and measured critical temperature was up to 15.7 K with the transition width 0.2-0.3 K for a 300 nm thick film. We measured the film critical magnetic field and studied influence of annealing on the film properties. We have investigated compositional depth profile of the deposited films by spectroscopy of reflected electrons.

  16. Nb3Al thin film deposition for low-noise terahertz electronics

    International Nuclear Information System (INIS)

    Dochev, D; Pavolotsky, A B; Belitsky, V; Olofsson, H

    2008-01-01

    Higher energy gap superconducting materials were always interesting for low-noise mixer applications such as superconductor-insulator-superconductor tunnel junctions (SIS) and hot-electron bolometer (HEB) used in sub-millimeter and terahertz parts of electro-magnetic spectrum. Here, we report a novel approach for producing Nb 3 Al thin film by co-sputtering from two confocally arranged Nb and Al dc-magnetrons onto substrate heated up to 830 deg. C. Characterization of the deposited films revealed presence of the A15 phase and measured critical temperature was up to 15.7 K with the transition width 0.2-0.3 K for a 300 nm thick film. We measured the film critical magnetic field and studied influence of annealing on the film properties. We have investigated compositional depth profile of the deposited films by spectroscopy of reflected electrons

  17. Simple and rapid quantification of total carotenoids in lyophilized apricots (prunus armeniaca L.) by means of reflectance colorimetry and photoacoustic spectrometry spectroscopy

    NARCIS (Netherlands)

    Doka, O.; Ficzek, G.; Luterotti, S.; Bicanic, D.D.; Spruijt, R.B.; Buijnsters, J.; Vegvari, G.

    2013-01-01

    Photoacoustic spectroscopy (PAS) and reflectance colorimetry are suggested as new tools for the analysis of total carotenoids in lyophilized apricot powders. The data obtained by these two techniques from seven apricot cultivars were compared to those acquired by spectrophotometry and

  18. CO 2 Capture Capacity and Swelling Measurements of Liquid-like Nanoparticle Organic Hybrid Materials via Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy

    KAUST Repository

    Park, Youngjune; Shin, Dolly; Jang, Young Nam; Park, Ah-Hyung Alissa

    2012-01-01

    attenuated total reflectance (ATR) Fourier transform infrared (FT-IR) spectroscopy. Simultaneous measurements of CO 2 capture capacity and swelling behaviors of polyetheramine (Jeffamine M-2070) and its corresponding NOHMs (NOHM-I-PE2070) were reported

  19. Optical reflection spectroscopy of thick corrosion layers on 304 stainless steel

    International Nuclear Information System (INIS)

    Castelli, R.A.; Persans, P.D.; Strohmayer, W.; Parkinson, V.

    2007-01-01

    Corrosion resistant structural materials of both iron and nickel based alloys are used in the electric power industry for the construction of the coolant loops of both conventional and nuclear power generating stations. These materials, in the presence of high temperature (e.g. 287 o C), high pH (e.g. 10.0 at 20 o C) water with dissolved hydrogen will oxidize and form corrosion films that are double metal oxides (or spinels) of the form AB 2 O 4 . This work describes optical reflectivity techniques that have been developed to study the growth of these films in situ. The optical technique uses a dual-beam specular reflection spectrometer to measure the spectrum of reflected light in small angle (i.e. o ) scatter. The reflection spectra are then calibrated using a set of corrosion coupons with corrosion films that are well known. Results are compared with models based on multilayer reflection and Mie scattering from a particle size distribution. Surface roughness is found to be the dominant cause of reduced reflection as the films grow

  20. Effective rumen degradation of dry matter, crude protein and neutral detergent fibre in forage determined by near infrared reflectance spectroscopy

    DEFF Research Database (Denmark)

    Ohlsson, C; Houmøller, L P; Weisbjerg, Martin Riis

    2007-01-01

    The objective of the present study was to examine if near infrared reflectance spectroscopy (NIRS) could be used to predict degradation parameters and effective degradation from scans of original forage samples. Degradability of dry matter (DM), crude protein (CP) and neutral detergent fibre (NDF......) of 61 samples of perennial ryegrass (Lolium perenne L.) and orchardgrass (Dactylis glomerata L.) was tested by using the in situ technique. The grass samples were harvested at three different stages, early vegetative growth, early reproductive growth and late reproductive growth. Degradability...

  1. Critical comparison of diffuse reflectance spectroscopy and colorimetry as dermatological diagnostic tools for acanthosis nigricans: a chemometric approach.

    Science.gov (United States)

    Devpura, Suneetha; Pattamadilok, Bensachee; Syed, Zain U; Vemulapalli, Pranita; Henderson, Marsha; Rehse, Steven J; Hamzavi, Iltefat; Lim, Henry W; Naik, Ratna

    2011-06-01

    Quantification of skin changes due to acanthosis nigricans (AN), a disorder common among insulin-resistant diabetic and obese individuals, was investigated using two optical techniques: diffuse reflectance spectroscopy (DRS) and colorimetry. Measurements were obtained from AN lesions on the neck and two control sites of eight AN patients. A principal component/discriminant function analysis successfully differentiated between AN lesion and normal skin with 87.7% sensitivity and 94.8% specificity in DRS measurements and 97.2% sensitivity and 96.4% specificity in colorimetry measurements.

  2. Attenuated total reflection UV spectroscopy for simultaneous analysis of alkali, sulphide and dissolved lignin in pulping liquors

    International Nuclear Information System (INIS)

    Chai, X.S.; Zhu, J.Y.; Luo, Q.; Li, J.

    2003-01-01

    This study experimentally demonstrated attenuated total reflection (ATR) ultraviolet (UV) spectroscopy for rapid and simultaneous determination of the concentrations of hydroxide, sulphide and dissolved lignin in kraft pulping liquors. A multivariate partial least squares fitting procedure (using commercially available software) was employed to obtain the species concentrations from the measured absorption spectra of the pulping liquors. Good agreements between ATR-UV measured species concentrations and those obtained by reference methods (titration for hydroxide and sulphide and conventional UV absorption for dissolved lignin) were achieved. (author)

  3. Determination of oxygen content and carbonate impurity in YBa2Cu3O7-x by diffuse reflectance infrared spectroscopy

    International Nuclear Information System (INIS)

    Merzbacher, C.I.; Bonner, B.P.

    1991-01-01

    Samples of YBa 2 Cu 3 O 7-x with x ranging from ∼0 to 0.65 have been analyzed by diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) in the midinfrared region (400--6000 cm -1 ). Spectral line shapes vary gradually as a function of oxygen stoichiometry, and the reflectance at 400 and 1000 cm -1 decreases linearly with decreasing oxygen content. Spectra of samples that were incompletely synthesized or exposed to a 4% CO 2 atmosphere at 650 degree C clearly indicated the presence of carbonate. DRIFTS is therefore a quick, nondestructive method for determining oxygen content in YBa 2 Cu 3 O 7-x powders, and for detecting carbonate species due to synthesis error or reaction with CO 2 -bearing atmosphere

  4. Total internal reflection sum-frequency generation spectroscopy and dense gold nanoparticles monolayer: a route for probing adsorbed molecules

    International Nuclear Information System (INIS)

    Tourillon, Gerard; Dreesen, Laurent; Volcke, Cedric; Sartenaer, Yannick; Thiry, Paul A; Peremans, Andre

    2007-01-01

    We show that sum-frequency generation spectroscopy performed in the total internal reflection configuration (TIR-SFG) combined with a dense gold nanoparticles monolayer allows us to study, with an excellent signal to noise ratio and high signal to background ratio, the conformation of adsorbed molecules. Dodecanethiol (DDT) was used as probe molecules in order to assess the potentialities of the approach. An enhancement of more than one order of magnitude of the SFG signals arising from the adsorbed species is observed with the TIR geometry compared to the external reflection one while the SFG non-resonant contribution remains the same for both configurations. Although further work is required to fully understand the origin of the SFG process on nanoparticles, our work opens new possibilities for studying nanostructures

  5. In vitro terahertz monitoring of muscle tissue dehydration under the action of hyperosmotic agents

    Energy Technology Data Exchange (ETDEWEB)

    Kolesnikov, A S; Kolesnikova, E A; Popov, A P; Tuchin, V V [N.G. Chernyshevsky Saratov State University, Saratov (Russian Federation); Nazarov, M M [Institute on Laser and Information Technologies, Russian Academy of Sciences, Shatura, Moscow Region (Russian Federation); Shkurinov, A P [International Laser Center, M. V. Lomonosov Moscow State University, Moscow (Russian Federation)

    2014-07-31

    Dehydration of muscle tissue in vitro under the action of biologically compatible hyperosmotic agents is studied using a laser terahertz spectrometer in the frequency range from 0.25 to 2.5 THz. Broadband terahertz absorption and reflection spectra of the bovine skeletal muscle tissue were obtained under the action of glycerol, polyethylene glycol with the molecular weight 600 (PEG-600), and propylene glycol. The presented results are proposed for application in developing the methods of image contrast enhancement and increasing the depth of biological tissue probing with terahertz radiation. (laser biophotonics)

  6. Reflections on hard X-ray photon-in/photon-out spectroscopy for electronic structure studies

    Energy Technology Data Exchange (ETDEWEB)

    Glatzel, Pieter, E-mail: glatzel@esrf.fr [European Synchrotron Radiation Facility, 6 Rue Jules Horowitz, 38043 Grenoble (France); Weng, Tsu-Chien; Kvashnina, Kristina; Swarbrick, Janine; Sikora, Marcin [European Synchrotron Radiation Facility, 6 Rue Jules Horowitz, 38043 Grenoble (France); Gallo, Erik [European Synchrotron Radiation Facility, 6 Rue Jules Horowitz, 38043 Grenoble (France); Department of Inorganic, Physical and Materials Chemistry, INSTM Reference Center and NIS Centre of Excellence, Università di Torino, Via P. Giuria 7, I-10125 Torino (Italy); Smolentsev, Nikolay [European Synchrotron Radiation Facility, 6 Rue Jules Horowitz, 38043 Grenoble (France); Research Center for Nanoscale Structure of Matter, Southern Federal University, str. Zorge 5, 344090 Rostov-on-Don (Russian Federation); Mori, Roberto Alonso [European Synchrotron Radiation Facility, 6 Rue Jules Horowitz, 38043 Grenoble (France)

    2013-06-15

    Highlights: ► Overview of some recent developments in hard X-ray RXES/RIXS. ► Evaluation of spectral line broadening in RXES/RIXS. ► Modelling of RXES/RIXS by ground state DFT calculations. ► Discussion on when HERFD provides a good approximation to XAS. -- Abstract: An increasing community of researchers in various fields of natural sciences is combining X-ray absorption with X-ray emission spectroscopy (XAS–XES) to study electronic structure. With the applications becoming more diverse, the objectives and the requirements in photon-in/photon-out spectroscopy are becoming broader. It is desirable to find simple experimental protocols, robust data reduction and theoretical tools that help the experimentalist to understand their data and learn about the electronic structure. This article presents a collection of considerations on non-resonant and resonant XES with the aim to guide the experimentalist to make good use of this technique.

  7. Reflection electron energy loss spectroscopy as efficient technique for the determination of optical properties of polystyrene intermixed with gold nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Deris, Jamileh [Department of Physics, Yasouj University, Yasouj 75918-74831 (Iran, Islamic Republic of); Hajati, Shaaker, E-mail: Hajati@mail.yu.ac.ir [Department of Physics, Yasouj University, Yasouj 75918-74831 (Iran, Islamic Republic of); Department of Semiconductors, Materials and Energy Research Center, Karaj 3177983634 (Iran, Islamic Republic of)

    2017-01-15

    Highlights: • Reflection Electron Energy Loss Spectroscopy of nano-metalized polymer. • Determination of real part of the dielectric function of nanostructured sample. • Determination of imaginary part of the dielectric function of nanostructured sample. • Determination of refractive index and coefficient of extinction of the sample. • Determination of reflection and absorption coefficients of nano-metalized Polymer. - Abstract: The electronic properties (electron inelastic cross section, energy loss function) of a nano-metalized polystyrene obtained by reflection electron energy loss spectroscopy (REELS) in a previous study [J. Deris, S. Hajati, S. Tougaard, V. Zaporojtchenko, Appl. Surf. Sci. 377 (2016) 44–47], which relies on the Yubero-Tougaard method, were used in the complementary application of Kramers-Kronig transformation to determine its optical properties such as the real part (ε{sub 1}) and imaginary part (ε{sub 2}) of the dielectric function (ε), refractive index (n), coefficients of extinction (k), reflection (R) and absorption (μ). The degree of intermixing of polystyrene thin film and gold nanoparticles of sizes 5.5 nm was controlled by annealing the sample to achieve a morphology in which the nanoparticles were homogeneously distributed within polystyrene. It is worth noting that no data are available on the optical properties of metalized polymers such as gold nanoparticles intermixed with polystyrene. Therefore, this work is of high importance in terms of both the sample studied here and the method applied. The advantage of the method applied here is that no information on the lateral distribution of the nanocomposite sample is required. This means that the REELS technique has been presented here to suitably, efficiently and easily obtain the optical properties of such nano-metalized polymer in which the metal nanoparticles have been vertically well distributed (homogeneous in depth). Therefore, for vertically homogeneous and

  8. Reflectance spectroscopy from TiO2 particles embedded in polyurethane

    DEFF Research Database (Denmark)

    Gudla, Visweswara Chakravarthy; Canulescu, Stela; Johansen, Villads Egede

    2013-01-01

    This paper presents the results of a physical simulation carried out using TiO2-Polyurethane composite coating on bright aluminium surface to understand the light scattering effect for designing white surfaces. Polyurethane matrix is selected due to the matching refractive index (1.7) with Al2O3...... layer on anodized aluminium surfaces. Three different TiO2 particle distributions were dispersed in polyurethane and spin coated onto high gloss and caustic etched aluminium substrates. Reflectance spectra of TiO2-polyurethane films of various concentrations were analysed using an integrating sphere....... The results show that the TiO2-polyurethane coatings have a high diffuse reflectance as a result of multiple scattering from TiO2 particles. Diffuse reflectance spectra of TiO2 containing films vary weakly with particle concentration and reach a steady state value at a concentration of 0.75 wt.%. Using...

  9. Optically Modulated Multiband Terahertz Perfect Absorber

    DEFF Research Database (Denmark)

    Seren, Huseyin R.; Keiser, George R.; Cao, Lingyue

    2014-01-01

    response of resonant metamaterials continues to be a challengingendeavor. Resonant perfect absorbers have flourished as one of the mostpromising metamaterial devices with applications ranging from power har-vesting to terahertz imaging. Here, an optically modulated resonant perfectabsorber is presented....... Utilizing photo-excited free carriers in silicon padsplaced in the capacitive gaps of split ring resonators, a dynamically modu-lated perfect absorber is designed and fabricated to operate in reflection.Large modulation depth (38% and 91%) in two absorption bands (with 97%and 92% peak absorption...

  10. Portable instrument that integrates irradiation with fluorescence and reflectance spectroscopies during clinical photodynamic therapy of cutaneous disease

    Science.gov (United States)

    Cottrell, W. J.; Oseroff, A. R.; Foster, T. H.

    2006-06-01

    We report a portable clinical instrument for delivering photodynamic therapy (PDT) while performing noninvasive spectroscopic monitoring in vivo. Using an off-surface probe, the instrument delivers the treatment beam to a user-defined field on the skin and performs reflectance and fluorescence spectroscopies at two regions within this field. The instrument is being used to monitor photosensitizer fluorescence photobleaching, fluorescent photoproduct kinetics, blood volume, and hemoglobin oxygen saturation during a pilot clinical trial of 5-aminolevulinic acid-PDT treatment of superficial basal cell carcinoma (BCC). Protoporphyrin IX and photoproduct fluorescence excited by the 633nm PDT treatment laser is collected between 655 and 800nm. During a series of brief treatment interruptions at programable time points, white light reflectance spectra between 475 and 800nm are acquired. Fluorescence spectra are corrected for the effects of absorption and scattering, informed by the reflectance measurements, and then decomposed into known fluorophore contributions in real time using a robust singular value decomposition fitting routine. Reflectance spectra additionally provide information on blood volume and hemoglobin oxygen saturation. Monitoring blood oxygenation and implicit dose metrics such as photosensitizer photobleaching during PDT allows the improved interpretation of clinical results and is helping to guide the treatment protocol for an anticipated low-irradiance PDT clinical trial of BCC.

  11. Preliminary evaluation of optical glucose sensing in red cell concentrations using near-infrared diffuse-reflectance spectroscopy

    Science.gov (United States)

    Suzuki, Yusuke; Maruo, Katsuhiko; Zhang, Alice W.; Shimogaki, Kazushige; Ogawa, Hideto; Hirayama, Fumiya

    2012-01-01

    Bacterial contamination of blood products is one of the most frequent infectious complications of transfusion. Since glucose levels in blood supplies decrease as bacteria proliferate, it should be possible to detect the presence of bacterial contamination by measuring the glucose concentrations in the blood components. Hence this study is aimed to serve as a preliminary study for the nondestructive measurement of glucose level in transfusion blood. The glucose concentrations in red blood cell (RBC) samples were predicted using near-infrared diffuse-reflectance spectroscopy in the 1350 to 1850 nm wavelength region. Furthermore, the effects of donor, hematocrit level, and temperature variations among the RBC samples were observed. Results showed that the prediction performance of a dataset which contained samples that differed in all three parameters had a standard error of 29.3 mg/dL. Multiplicative scatter correction (MSC) preprocessing method was also found to be effective in minimizing the variations in scattering patterns created by various sample properties. The results suggest that the diffuse-reflectance spectroscopy may provide another avenue for the detection of bacterial contamination in red cell concentrations (RCC) products.

  12. Non-destructive evaluation of degradation in EB-PVD thermal barrier coatings by infrared reflectance spectroscopy

    International Nuclear Information System (INIS)

    Flattum, Richard Y.; Cooney, Adam T.

    2013-01-01

    At room temperature and atmospheric conditions infrared reflectance spectroscopy and X-ray diffraction were employed for the detection of the phase transformation and residual stress within thermal barrier coatings (TBC). The TBC's samples initially consisted of the porous ceramic topcoat deposited by electron beam plasma vapor deposition, a bond coat and a superalloy substrate. Reflectance spectroscopy scans were performed from 7497 cm −1 to 68 cm −1 to analysis the fingerprint region as well as the chemical bonding region. These regions should indicate if a detectable change within the TBC response is a result of thermal degradation of the microstructure and the changes in yttrium dispersion throughout the yttrium stabilized zirconium. The thermal degradation was induced by thermal cycling the samples to 1100° C and then cooling them in an atmospheric environment. X-ray diffraction was also used to detect the phase composition within the TBC samples and see if either would clearly identify failure prior to actual spallation. The eventual measurability and quantify-ability of the phase changes within the TBC's may be used as an effective non-destructive evaluation (NDE) technique that would allow personnel in the field to know when servicing of the turbine blade was necessary.

  13. In vivo characterization of colorectal metastases in human liver using diffuse reflectance spectroscopy: toward guidance in oncological procedures

    Science.gov (United States)

    Spliethoff, Jarich W.; de Boer, Lisanne L.; Meier, Mark A. J.; Prevoo, Warner; de Jong, Jeroen; Kuhlmann, Koert; Bydlon, Torre M.; Sterenborg, Henricus J. C. M.; Hendriks, Benno H. W.; Ruers, Theo J. M.

    2016-09-01

    There is a strong need to develop clinical instruments that can perform rapid tissue assessment at the tip of smart clinical instruments for a variety of oncological applications. This study presents the first in vivo real-time tissue characterization during 24 liver biopsy procedures using diffuse reflectance (DR) spectroscopy at the tip of a core biopsy needle with integrated optical fibers. DR measurements were performed along each needle path, followed by biopsy of the target lesion using the same needle. Interventional imaging was coregistered with the DR spectra. Pathology results were compared with the DR spectroscopy data at the final measurement position. Bile was the primary discriminator between normal liver tissue and tumor tissue. Relative differences in bile content matched with the tissue diagnosis based on histopathological analysis in all 24 clinical cases. Continuous DR measurements during needle insertion in three patients showed that the method can also be applied for biopsy guidance or tumor recognition during surgery. This study provides an important validation step for DR spectroscopy-based tissue characterization in the liver. Given the feasibility of the outlined approach, it is also conceivable to make integrated fiber-optic tools for other clinical procedures that rely on accurate instrument positioning.

  14. Study of Surface Wettability Change of Unconsolidated Sand Using Diffuse Reflectance Infrared Fourier Transform Spectroscopy and Thermogravimetric Analysis.

    Science.gov (United States)

    Gómora-Herrera, Diana; Navarrete Bolaños, Juan; Lijanova, Irina V; Olivares-Xometl, Octavio; Likhanova, Natalya V

    2018-04-01

    The effects exerted by the adsorption of vapors of a non-polar compound (deuterated benzene) and a polar compound (water) on the surface of Ottawa sand and a sample of reservoir sand (Channel), which was previously impregnated with silicon oil or two kinds of surfactants, (2-hydroxyethyl) trimethylammonium oleate (HETAO) and (2-hydroxyethyl)trimethylammonium azelate (HETAA), were studied by diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and thermogravimetric analysis (TGA). The surface chemistry of the sandstone rocks was elucidated by X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDX). Terminal surface groups such as hydroxyls can strongly adsorb molecules that interact with these surface groups (surfactants), resulting in a wettability change. The wettability change effect suffered by the surface after treating it with surfactants was possible to be detected by the DRIFTS technique, wherein it was observed that the surface became more hydrophobic after being treated with silicon oil and HETAO; the surface became more hydrophilic after treating it with HETAA.

  15. The application of Near Infrared Reflectance Spectroscopy (NIRS for the quantitative analysis of hydrocortisone in primary materials

    Directory of Open Access Journals (Sweden)

    A. PITTAS

    2001-03-01

    Full Text Available Near Infrared Reflectance Spectroscopy (NIRS, coupled with fiber optic probes, has been shown to be a quick and reliable analytical tool for quality assurance and quality control in the pharmaceutical industry, both for verifications of raw materials and quantification of the active ingredients in final products. In this paper, a typical pharmaceutical product, hydrocortisone sodium succinate, is used as an example for the application of NIR spectroscopy for quality control. In order to develop an NIRS method with higher precision and accuracy than the official UV/VIS spectroscopic method (BP '99, 19 samples, taken from one year’s production and several prepared in the laboratory, having a hydrocortisone sodium succinate concentration in the range from 89.05%to 95.83 %, were analysed by NIR and UV/VIS spectroscopy. Three frequency ranges: 5939.73–5627.32 cm-1; 4863.64 – 4574.36 cm-1; 4308.23–4200.24 cm-1, with the best positive correlation between the changes in the spectral and concentration data, were chosen. The validity of the developed NIRS chemometric method for the determination of the hydrocortisone sodium succinate concentration, constructed by the partial least squares (PLS regression technique, is discussed. A correlation coefficient of 0.9758 and a standard error of cross validation (RMSECVof 1.06%were found between the UV/VI Sand òhe NIR spectroscopic results of the hydrocortisone sodium succinate concentration in the samples.

  16. Terahertz pulse imaging for tree-ring analysis: a preliminary study for dendrochronology applications

    International Nuclear Information System (INIS)

    Jackson, J B; Mourou, M; Whitaker, J F; Labaune, J; Mourou, G A; Duling, I N III; Williamson, S L; Lavier, C; Menu, M

    2009-01-01

    Time-domain terahertz reflection imaging is presented as a novel method of measuring otherwise inaccessible tree rings in wooden cultural heritage for the purpose of tree-ring crossdating. Axial and lateral two-dimensional terahertz images of obscured ring patterns are statistically validated with respect to their corresponding optical photographs via adapted dendrochronological methods. Results are compared to similar analysis of x-ray images of a wood specimen

  17. Quantification of SOC and Clay Content Using Visible Near-Infrared Reflectance–Mid-Infrared Reflectance Spectroscopy With Jack-Knifing Partial Least Squares Regression

    DEFF Research Database (Denmark)

    Peng, Yi; Knadel, Maria; Gislum, René

    2014-01-01

    A total of 125 soil samples were collected from a Danish field varying in soil texture from sandy to loamy. Visible near-infrared reflectance (Vis-NIR) and mid-infrared reflectance (MIR) spectroscopy combined with chemometric methods were used to predict soil organic carbon (SOC) and clay content...

  18. ChemCam passive reflectance spectroscopy of surface materials at the Curiosity landing site, Mars

    Science.gov (United States)

    Johnson, Jeffrey R.; Bell, J. F.; Bender, S.; Blaney, D.; Cloutis, E.; DeFlores, L.; Ehlmann, B.; Gasnault, O.; Gondet, B.; Kinch, K.; Lemmon, M.; Le Mouélic, S.; Maurice, S.; Rice, M.; Wiens, R. C.

    2015-03-01

    The spectrometers on the Mars Science Laboratory (MSL) ChemCam instrument were used in passive mode to record visible/near-infrared (400-840 nm) radiance from the martian surface. Using the onboard ChemCam calibration targets' housing as a reflectance standard, we developed methods to collect, calibrate, and reduce radiance observations to relative reflectance. Such measurements accurately reproduce the known reflectance spectra of other calibration targets on the rover, and represent the highest spatial resolution (0.65 mrad) and spectral sampling (rocks and soils match those from orbital observations and multispectral data from the MSL Mastcam camera. Preliminary analyses of the band depths, spectral slopes, and reflectance ratios of the more than 2000 spectra taken during the first year of MSL operations demonstrate at least six spectral classes of materials distinguished by variations in ferrous and ferric components. Initial comparisons of ChemCam spectra to laboratory spectra of minerals and Mars analog materials demonstrate similarities with palagonitic soils and indications of orthopyroxene in some dark rocks. Magnesium-rich "raised ridges" tend to exhibit distinct near-infrared slopes. The ferric absorption downturn typically found for martian materials at rocks and drill tailings, consistent with their more ferrous nature. Calcium-sulfate veins exhibit the highest relative reflectances observed, but are still relatively red owing to the effects of residual dust. Such dust is overall less prominent on rocks sampled within the "blast zone" immediately surrounding the landing site. These samples were likely affected by the landing thrusters, which partially removed the ubiquitous dust coatings. Increased dust coatings on the calibration targets during the first year of the mission were documented by the ChemCam passive measurements as well. Ongoing efforts to model and correct for this dust component should improve calibration of the relative reflectance

  19. Terahertz applications in cultural heritage: case studies

    Science.gov (United States)

    Giovannacci, D.; Martos-Levif, D.; Walker, G. C.; Menu, M.; Detalle, V.

    2013-11-01

    Terahertz (THz) spectroscopy and imaging is a non-destructive, non-contact, non-invasive technology emerging as a tool for the analysis of cultural heritage. THz Time Domain Spectroscopy (TDS) techniques have the ability to retrieve information from different layers within a stratified sample, that enable the identification of hidden sub-layers in the case of paints and mural paintings. In this paper, we present the THz TDS2 system developed in the European Commission's 7th Framework Program project CHARISMA [grant agreement no. 228330]. Bespoke single processing algorithms; including a deconvolution algorithm can be deployed to increase the resolution and the global performance of the system. The potential and impact of this work is demonstrated through two case studies of mural paintings, where the capability to reveal the stratigraphy of the artworks is demonstrated.

  20. An investigation of Oxygen adsorption on W(110) using reflectance anisotropy spectroscopy

    International Nuclear Information System (INIS)

    Zeybek, O.

    2004-01-01

    The probe of metal surface electronic structure and results of the oxidation of a BCC material and the first Joint Density of States interpretation of the spectrum from same metal have been presented. The surface sensitivity of RAS has been exploited when applied to a cubic single crystal to study the surface electronic structure of W(110) and the resulting chemisorption-induced changes upon exposure to oxygen. Oxidation of the surface is monitored until a final exposure of 10 Langmuirs is reached. A decrease of reflectance anisotropy signal is obtained with increasing oxygen coverage on the substrate and a coverage of ∼0.75 ML results in zero anisotropy over the reflectance anisotropy energy range

  1. An investigation of Oxygen adsorption on W(110) using reflectance anisotropy spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Zeybek, O [Department of Physics, Balikesir University, Balikesir (Turkey)

    2004-07-01

    The probe of metal surface electronic structure and results of the oxidation of a BCC material and the first Joint Density of States interpretation of the spectrum from same metal have been presented. The surface sensitivity of RAS has been exploited when applied to a cubic single crystal to study the surface electronic structure of W(110) and the resulting chemisorption-induced changes upon exposure to oxygen. Oxidation of the surface is monitored until a final exposure of 10 Langmuirs is reached. A decrease of reflectance anisotropy signal is obtained with increasing oxygen coverage on the substrate and a coverage of {approx}0.75 ML results in zero anisotropy over the reflectance anisotropy energy range.

  2. Plasmonic reflectance anisotropy spectroscopy of metal nanoparticles on a semiconductor surface

    Science.gov (United States)

    Kosobukin, V. A.; Korotchenkov, A. V.

    2016-12-01

    A theory of plasmonic differential anisotropic reflection of light from nanoparticles located near the interface between media is developed. The model of a monolayer consisting of identical ellipsoidal metal particles occupying sites of a rectangular lattice is investigated. Effective plasmonic polarizabilities of nanoparticles in the layer are calculated self-consistently using the Green's function technique in the quasipoint dipole approximation. The local-field effect caused by anisotropic dipole plasmons of particles in the layer and their image dipoles is taken into account. The lately observed resonant reflectance anisotropy spectra of indium nanoclusters on InAs surface are explained by the difference between frequencies of plasmons with the orthogonal polarizations in the surface plane. The difference between the plasmon frequencies is attributed to anisotropy of the particles shape or/and the layer structure; the signs of frequency difference for the two types of anisotropy being different.

  3. Using Reflectance Spectroscopy and Artificial Neural Network to Assess Water Infiltration Rate into the Soil Profile

    Directory of Open Access Journals (Sweden)

    Naftali Goldshleger

    2012-01-01

    Full Text Available We explored the effect of raindrop energy on both water infiltration into soil and the soil's NIR-SWIR spectral reflectance (1200–2400 nm. Seven soils with different physical and morphological properties from Israel and the US were subjected to an artificial rainstorm. The spectral properties of the crust formed on the soil surface were analyzed using an artificial neural network (ANN. Results were compared to a study with the same population in which partial least-squares (PLS regression was applied. It was concluded that both models (PLS regression and ANN are generic as they are based on properties that correlate with the physical crust, such as clay content, water content and organic matter. Nonetheless, better results for the connection between infiltration rate and spectral properties were achieved with the non-linear ANN technique in terms of statistical values (RMSE of 17.3% for PLS regression and 10% for ANN. Furthermore, although both models were run at the selected wavelengths and their accuracy was assessed with an independent external group of samples, no pre-processing procedure was applied to the reflectance data when using ANN. As the relationship between infiltration rate and soil reflectance is not linear, ANN methods have the advantage for examining this relationship when many soils are being analyzed.

  4. Continuous-wave cavity ringdown spectroscopy based on the control of cavity reflection.

    Science.gov (United States)

    Li, Zhixin; Ma, Weiguang; Fu, Xiaofang; Tan, Wei; Zhao, Gang; Dong, Lei; Zhang, Lei; Yin, Wangbao; Jia, Suotang

    2013-07-29

    A new type of continuous-wave cavity ringdown spectrometer based on the control of cavity reflection for trace gas detection was designed and evaluated. The technique separated the acquisitions of the ringdown event and the trigger signal to optical switch by detecting the cavity reflection and transmission, respectively. A detailed description of the time sequence of the measurement process was presented. In order to avoid the wrong extraction of ringdown time encountered accidentally in fitting procedure, the laser frequency and cavity length were scanned synchronously. Based on the statistical analysis of measured ringdown times, the frequency normalized minimum detectable absorption in the reflection control mode was 1.7 × 10(-9)cm(-1)Hz(-1/2), which was 5.4 times smaller than that in the transmission control mode. However the signal-to-noise ratio of the absorption spectrum was only 3 times improved since the etalon effect existed. Finally, the peak absorption coefficients of the C(2)H(2) transition near 1530.9nm under different pressures showed a good agreement with the theoretical values.

  5. Pressure-modulation dynamic attenuated-total-reflectance (ATR) FT-IR spectroscopy

    Science.gov (United States)

    Marcott, C.; Story, G. M.; Noda, I.; Bibby, A.; Manning, C. J.

    1998-06-01

    A single-reflectance attenuated-total-reflectance (ATR) accessory with a diamond internal-reflection element was modified by the addition of a piezoelectric transducer. Initial dynamic pressure-modulation experiments have been performed in the sample compartment of a step-scanning FT-IR spectrometer. A sinusoidal pressure modulation applied to samples of isotactic polypropylene and linear low density polyethylene resulted in dynamic responses which appear to be similar to those observed in previous dynamic 2D IR experiments. Preliminary pressure-modulation dynamic ATR results are also reported for a styrene-butadiene-styrene triblock copolymer. The new method has the advantages that a much wider variety of sample types and geometries can be studied and less sample preparation is required. Dynamic 2D IR experiments carried out by ATR no longer require thin films of large area and sufficient strength to withstand the dynamic strain applied by a rheometer. The ability to obtain dynamic IR spectroscopic information from a wider variety of sample types and thicknesses would greatly expand the amount of useful information that could be extracted from normally complicated, highly overlapped IR spectra.

  6. Superiority of terahertz over infrared transmission through bandages and burn wound ointments

    International Nuclear Information System (INIS)

    Suen, Jonathan Y.; Padilla, Willie J.

    2016-01-01

    Terahertz electromagnetic waves have long been proposed to be ideal for spectroscopy and imaging through non-polar dielectric materials that contain no water. Terahertz radiation may thus be useful for monitoring burn and wound injury recovery, as common care treatments involve application of both a clinical dressing and topical ointment. Here, we investigate the optical properties of typical care treatments in the millimeter wave (150–300 GHz), terahertz (0.3–3 THz), and infrared (14.5–0.67 μm) ranges of the electromagnetic spectrum. We find that THz radiation realizes low absorption coefficients and high levels of transmission compared to infrared wavelengths, which were strongly attenuated. Terahertz imaging can enable safe, non-ionizing, noninvasive monitoring of the healing process directly through clinical dressings and recovery ointments, minimizing the frequency of dressing changes and thus increasing the rate of the healing process.

  7. Superiority of terahertz over infrared transmission through bandages and burn wound ointments

    Energy Technology Data Exchange (ETDEWEB)

    Suen, Jonathan Y., E-mail: j.suen@duke.edu; Padilla, Willie J. [Department of Electrical and Computer Engineering, Duke University, Durham, North Carolina 27708 (United States)

    2016-06-06

    Terahertz electromagnetic waves have long been proposed to be ideal for spectroscopy and imaging through non-polar dielectric materials that contain no water. Terahertz radiation may thus be useful for monitoring burn and wound injury recovery, as common care treatments involve application of both a clinical dressing and topical ointment. Here, we investigate the optical properties of typical care treatments in the millimeter wave (150–300 GHz), terahertz (0.3–3 THz), and infrared (14.5–0.67 μm) ranges of the electromagnetic spectrum. We find that THz radiation realizes low absorption coefficients and high levels of transmission compared to infrared wavelengths, which were strongly attenuated. Terahertz imaging can enable safe, non-ionizing, noninvasive monitoring of the healing process directly through clinical dressings and recovery ointments, minimizing the frequency of dressing changes and thus increasing the rate of the healing process.

  8. NuSTAR SPECTROSCOPY OF MULTI-COMPONENT X-RAY REFLECTION FROM NGC 1068

    Energy Technology Data Exchange (ETDEWEB)

    Bauer, Franz E. [Pontificia Universidad Católica de Chile, Instituto de Astrofísica, Casilla 306, Santiago 22 (Chile); Arévalo, Patricia [EMBIGGEN Anillo, Concepción (Chile); Walton, Dominic J.; Baloković, Mislav; Brightman, Murray; Harrison, Fiona A. [Cahill Center for Astronomy and Astrophysics, California Institute of Technology, Pasadena, CA 91125 (United States); Koss, Michael J. [Institute for Astronomy, Department of Physics, ETH Zurich, Wolfgang-Pauli-Strasse 27, CH-8093 Zurich (Switzerland); Puccetti, Simonetta [ASDC-ASI, Via del Politecnico, I-00133 Roma (Italy); Gandhi, Poshak [School of Physics and Astronomy, University of Southampton, Highfield, Southampton SO17 1BJ (United Kingdom); Stern, Daniel [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States); Alexander, David M.; Moro, Agnese Del [Department of Physics, Durham University, South Road, Durham, DH1 3LE (United Kingdom); Boggs, Steve E.; Craig, William W. [Space Sciences Laboratory, University of California, Berkeley, CA 94720 (United States); Brandt, William N.; Luo, Bin [Department of Astronomy and Astrophysics, The Pennsylvania State University, 525 Davey Lab, University Park, PA 16802 (United States); Christensen, Finn E. [DTU Space, National Space Institute, Technical University of Denmark, Elektrovej 327, DK-2800 Lyngby (Denmark); Comastri, Andrea [INAF-Osservatorio Astronomico di Bologna, via Ranzani 1, I-40127 Bologna (Italy); Hailey, Charles J. [Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027 (United States); Hickox, Ryan [Department of Physics and Astronomy, Dartmouth College, 6127 Wilder Laboratory, Hanover, NH 03755 (United States); and others

    2015-10-20

    We report on high-energy X-ray observations of the Compton-thick Seyfert 2 galaxy NGC 1068 with NuSTAR, which provide the best constraints to date on its >10 keV spectral shape. The NuSTAR data are consistent with those from past and current instruments to within cross-calibration uncertainties, and we find no strong continuum or line variability over the past two decades, which is in line with its X-ray classification as a reflection-dominated Compton-thick active galactic nucleus. The combined NuSTAR, Chandra, XMM-Newton, and Swift BAT spectral data set offers new insights into the complex secondary emission seen instead of the completely obscured transmitted nuclear continuum. The critical combination of the high signal-to-noise NuSTAR data and the decomposition of the nuclear and extranuclear emission with Chandra allow us to break several model degeneracies and greatly aid physical interpretation. When modeled as a monolithic (i.e., a single N{sub H}) reflector, none of the common Compton reflection models are able to match the neutral fluorescence lines and broad spectral shape of the Compton reflection hump without requiring unrealistic physical parameters (e.g., large Fe overabundances, inconsistent viewing angles, or poor fits to the spatially resolved spectra). A multi-component reflector with three distinct column densities (e.g., with best-fit values of N{sub H} of 1.4 × 10{sup 23}, 5.0 × 10{sup 24}, and 10{sup 25} cm{sup −2}) provides a more reasonable fit to the spectral lines and Compton hump, with near-solar Fe abundances. In this model, the higher N{sub H} component provides the bulk of the flux to the Compton hump, while the lower N{sub H} component produces much of the line emission, effectively decoupling two key features of Compton reflection. We find that ≈30% of the neutral Fe Kα line flux arises from >2″ (≈140 pc) and is clearly extended, implying that a significant fraction (and perhaps most) of the <10 keV reflected component

  9. Experimental Realization of an Epsilon-Near-Zero Graded-Index Metalens at Terahertz Frequencies

    Science.gov (United States)

    Pacheco-Peña, Victor; Engheta, Nader; Kuznetsov, Sergei; Gentselev, Alexandr; Beruete, Miguel

    2017-09-01

    The terahertz band has been historically hindered by the lack of efficient generators and detectors, but a series of recent breakthroughs have helped to effectively close the "terahertz gap." A rapid development of terahertz technology has been possible thanks to the translation of revolutionary concepts from other regions of the electromagnetic spectrum. Among them, metamaterials stand out for their unprecedented ability to control wave propagation and manipulate electromagnetic response of matter. They have become a workhorse in the development of terahertz devices such as lenses, polarizers, etc., with fascinating features. In particular, epsilon-near-zero (ENZ) metamaterials have attracted much attention in the past several years due to their unusual properties such as squeezing, tunneling, and supercoupling where a wave traveling inside an electrically small channel filled with an ENZ medium can be tunneled through it, reducing reflections and coupling most of its energy. Here, we design and experimentally demonstrate an ENZ graded-index (GRIN) metamaterial lens operating at terahertz with a power enhancement of 16.2 dB, using an array of narrow hollow rectangular waveguides working near their cutoff frequencies. This is a demonstration of an ENZ GRIN device at terahertz and can open the path towards other realizations of similar devices enabling full quasioptical processing of terahertz signals.

  10. FDTD-based quantitative analysis of terahertz wave detection for multilayered structures.

    Science.gov (United States)

    Tu, Wanli; Zhong, Shuncong; Shen, Yaochun; Zhou, Qing; Yao, Ligang

    2014-10-01

    Experimental investigations have shown that terahertz pulsed imaging (TPI) is able to quantitatively characterize a range of multilayered media (e.g., biological issues, pharmaceutical tablet coatings, layered polymer composites, etc.). Advanced modeling of the interaction of terahertz radiation with a multilayered medium is required to enable the wide application of terahertz technology in a number of emerging fields, including nondestructive testing. Indeed, there have already been many theoretical analyses performed on the propagation of terahertz radiation in various multilayered media. However, to date, most of these studies used 1D or 2D models, and the dispersive nature of the dielectric layers was not considered or was simplified. In the present work, the theoretical framework of using terahertz waves for the quantitative characterization of multilayered media was established. A 3D model based on the finite difference time domain (FDTD) method is proposed. A batch of pharmaceutical tablets with a single coating layer of different coating thicknesses and different refractive indices was modeled. The reflected terahertz wave from such a sample was computed using the FDTD method, assuming that the incident terahertz wave is broadband, covering a frequency range up to 3.5 THz. The simulated results for all of the pharmaceutical-coated tablets considered were found to be in good agreement with the experimental results obtained using a commercial TPI system. In addition, we studied a three-layered medium to mimic the occurrence of defects in the sample.

  11. Proton magnetic resonance spectroscopy reflects metabolic decompensation in maple syrup urine disease

    Energy Technology Data Exchange (ETDEWEB)

    Heindel, W. [Dept. of Diagnostic Radiology, Univ. Koeln (Germany); Kugel, H. [Dept. of Diagnostic Radiology, Univ. Koeln (Germany); Wendel, U. [Children`s Hospital, Univ. Duesseldorf (Germany); Roth, B. [Children`s Hospital, Univ. Koeln (Germany); Benz-Bohm, G. [Dept. of Diagnostic Radiology, Univ. Koeln (Germany)

    1995-06-01

    Using localized proton magnetic resonance spectroscopy ({sup 1}H-MRS), accumulation of branchedchain amino acids (BCAA) and their corresponding 2-oxo acids (BCOA) could be non-invasively demonstrated in the brain of a 9-year-old girl suffering from classical maple syrup urine disease. During acute metabolic decompensation, the compounds caused a signal at a chemical shift of 0.9 ppm which was assigned by in vitro experiments. The brain tissue concentration of the sum of BCAA and BCOA could be estimated as 0.9 mmol/l. Localized {sup 1}H-MRS of the brain appears to be suitable for examining patients suffering from maple syrup urine disease in different metabolic states. (orig.)

  12. Proton magnetic resonance spectroscopy reflects metabolic decompensation in maple syrup urine disease

    International Nuclear Information System (INIS)

    Heindel, W.; Kugel, H.; Wendel, U.; Roth, B.; Benz-Bohm, G.

    1995-01-01

    Using localized proton magnetic resonance spectroscopy ( 1 H-MRS), accumulation of branchedchain amino acids (BCAA) and their corresponding 2-oxo acids (BCOA) could be non-invasively demonstrated in the brain of a 9-year-old girl suffering from classical maple syrup urine disease. During acute metabolic decompensation, the compounds caused a signal at a chemical shift of 0.9 ppm which was assigned by in vitro experiments. The brain tissue concentration of the sum of BCAA and BCOA could be estimated as 0.9 mmol/l. Localized 1 H-MRS of the brain appears to be suitable for examining patients suffering from maple syrup urine disease in different metabolic states. (orig.)

  13. Fingerprint extraction from interference destruction terahertz spectrum.

    Science.gov (United States)

    Xiong, Wei; Shen, Jingling

    2010-10-11

    In this paper, periodic peaks in a terahertz absorption spectrum are confirmed to be induced from interference effects. Theoretically, we explained the periodic peaks and calculated the locations of them. Accordingly, a technique was suggested, with which the interference peaks in a terahertz spectrum can be eliminated and therefore a real terahertz absorption spectrum can be obtained. Experimentally, a sample, Methamphetamine, was investigated and its terahertz fingerprint was successfully extracted from its interference destruction spectrum. This technique is useful in getting samples' terahertz fingerprint spectra, and furthermore provides a fast nondestructive testing method using a large size terahertz beam to identify materials.

  14. Early detection of melanoma with the combined use of acoustic microscopy, infrared reflectance and Raman spectroscopy

    Science.gov (United States)

    Karagiannis, Georgios T.; Grivas, Ioannis; Tsingotjidou, Anastasia; Apostolidis, Georgios K.; Grigoriadou, Ifigeneia; Dori, I.; Poulatsidou, Kyriaki-Nefeli; Doumas, Argyrios; Wesarg, Stefan; Georgoulias, Panagiotis

    2015-03-01

    Malignant melanoma is a form of skin cancer, with increasing incidence worldwide. Early diagnosis is crucial for the prognosis and treatment of the disease. The objective of this study is to develop a novel animal model of melanoma and apply a combination of the non-invasive imaging techniques acoustic microscopy, infrared (IR) and Raman spectroscopies, for the detection of developing tumors. Acoustic microscopy provides information about the 3D structure of the tumor, whereas, both spectroscopic modalities give qualitative insight of biochemical changes during melanoma development. In order to efficiently set up the final devices, propagation of ultrasonic and electromagnetic waves in normal skin and melanoma simulated structures was performed. Synthetic and grape-extracted melanin (simulated tumors), endermally injected, were scanned and compared to normal skin. For both cases acoustic microscopy with central operating frequencies of 110MHz and 175MHz were used, resulting to the tomographic imaging of the simulated tumor, while with the spectroscopic modalities IR and Raman differences among spectra of normal and melanin- injected sites were identified in skin depth. Subsequently, growth of actual tumors in an animal melanoma model, with the use of human malignant melanoma cells was achieved. Acoustic microscopy and IR and Raman spectroscopies were also applied. The development of tumors at different time points was displayed using acoustic microscopy. Moreover, the changes of the IR and Raman spectra were studied between the melanoma tumors and adjacent healthy skin. The most significant changes between healthy skin and the melanoma area were observed in the range of 900-1800cm-1 and 350-2000cm-1, respectively.

  15. Discrimination of the hard keratins animal horn and chelonian shell using attenuated total reflection-infrared spectroscopy.

    Science.gov (United States)

    Biscardi, Brianna; Welsh, Wendy; Kennedy, Anthony

    2012-05-01

    The ability to discriminate between objects manufactured from animal horn and chelonian (turtle, tortoise, or terrapin) shell is important from a cultural and archeological perspective such that it may allow conservators to determine the appropriate treatment and long-term care solution. It would also aid curators in identifying and cataloging items manufactured from these materials. Discrimination and classification is also a valuable tool for those involved in tracking the illegal trade in restricted materials of this nature. Attenuated total reflection infrared (ATR-IR) spectroscopy, using a single reflection diamond internal reflection element (IRE), coupled with discrimination analysis was used to analyze a total of thirty-nine samples (29 calibration samples, 10 validation samples). A discrimination analysis model was constructed using Mahalanobis distances to classify spectra into one of two classes. The model was then subsequently used to successfully classify all validation samples and correctly identify them as animal horn or chelonian shell based on second-derivative spectra of the amide I and II regions. This technique requires minimal to no sample preparation and may be used to nondestructively identify very small samples successfully without performing detailed secondary structural curve-fitting routines. This model should be a valuable resource to museums, conservators, and wildlife management programs for rapidly and reliably discriminating between animal horn and chelonian shell.

  16. NuSTAR SPECTROSCOPY OF GRS 1915+105: DISK REFLECTION, SPIN, AND CONNECTIONS TO JETS

    Energy Technology Data Exchange (ETDEWEB)

    Miller, J. M.; King, A. L. [Department of Astronomy, The University of Michigan, 500 Church Street, Ann Arbor, MI 48109-1046 (United States); Parker, M. L.; Fabian, A. C. [Institute of Astronomy, The University of Cambridge, Madingley Road, Cambridge CB3 OHA (United Kingdom); Fuerst, F.; Walton, D. J. [Cahill Center for Astronomy and Astrophysics, California Institute of Technology, Pasadena, CA, 91125 (United States); Bachetti, M.; Harrison, F. A.; Barret, D.; Grefenstette, B. W. [Universite de Toulouse, UPS-OMP, F-31400 Toulouse (France); Boggs, S. E.; Tomsick, J. A. [Space Sciences Laboratory, University of California, Berkeley, 7 Gauss Way, Berkeley, CA 94720-7450 (United States); Chakrabarty, D. [Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, 70 Vassar Street, Cambridge, MA 02139 (United States); Christensen, F. E. [Danish Technical University, DK-2800 Lyngby (Denmark); Craig, W. W. [Lawrence Livermore National Laboratory, Livermore, CA (United States); Hailey, C. J. [Columbia University, New York, NY 10027 (United States); Stern, D. K. [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States); Zhang, W. W., E-mail: jonmm@umich.edu [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

    2013-10-01

    We report on the results of spectral fits made to a NuSTAR observation of the black hole GRS 1915+105 in a 'plateau' state. This state is of special interest because it is similar to the 'low/hard' state seen in other black holes, especially in that compact, steady jets are launched in this phase. The 3-79 keV bandpass of NuSTAR, and its ability to obtain moderate-resolution spectra free from distortions such as photon pile-up, are extremely well suited to studies of disk reflection in X-ray binaries. In only 15 ks of net exposure, an extraordinarily sensitive spectrum of GRS 1915+105 was measured across the full bandpass. Ionized reflection from a disk around a rapidly spinning black hole is clearly required to fit the spectra; even hybrid Comptonization models including ionized reflection from a disk around a Schwarzschild black hole proved inadequate. A spin parameter of a = 0.98 ± 0.01 (1σ statistical error) is measured via the best-fit model; low spins are ruled out at a high level of confidence. This result suggests that jets can be launched from a disk extending to the innermost stable circular orbit. A very steep inner disk emissivity profile is also measured, consistent with models of compact coronae above Kerr black holes. These results support an emerging association between the hard X-ray corona and the base of the relativistic jet.

  17. Identification of Uranium Minerals in Natural U-Bearing Rocks Using Infrared Reflectance Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Beiswenger, Toya N. [Pacific Northwest National Laboratory, Richland, WA, USA; Gallagher, Neal B. [Eigenvector Research, Inc., Manson, WA, USA; Myers, Tanya L. [Pacific Northwest National Laboratory, Richland, WA, USA; Szecsody, James E. [Pacific Northwest National Laboratory, Richland, WA, USA; Tonkyn, Russell G. [Pacific Northwest National Laboratory, Richland, WA, USA; Su, Yin-Fong [Pacific Northwest National Laboratory, Richland, WA, USA; Sweet, Lucas E. [Pacific Northwest National Laboratory, Richland, WA, USA; Lewallen, Tricia A. [Pacific Northwest National Laboratory, Richland, WA, USA; Johnson, Timothy J. [Pacific Northwest National Laboratory, Richland, WA, USA

    2017-10-24

    The identification of minerals, including uranium-bearing minerals, is traditionally a labor-intensive-process using x-ray diffraction (XRD), fluorescence, or other solid-phase and wet chemical techniques. While handheld XRD and fluorescence instruments can aid in field identification, handheld infrared reflectance spectrometers can also be used in industrial or field environments, with rapid, non-destructive identification possible via spectral analysis of the solid’s reflectance spectrum. We have recently developed standard laboratory measurement methods for the infrared (IR) reflectance of solids and have investigated using these techniques for the identification of uranium-bearing minerals, using XRD methods for ground-truth. Due to the rich colors of such species, including distinctive spectroscopic signatures in the infrared, identification is facile and specific, both for samples that are pure or are partially composed of uranium (e.g. boltwoodite, schoepite, tyuyamunite, carnotite, etc.) or non-uranium minerals. The method can be used to detect not only pure and partial minerals, but is quite sensitive to chemical change such as hydration (e.g. schoepite). We have further applied statistical methods, in particular classical least squares (CLS) and multivariate curve resolution (MCR) for discrimination of such uranium minerals and two uranium pure chemicals (U3O8 and UO2) against common background materials (e.g. silica sand, asphalt, calcite, K-feldspar) with good success. Each mineral contains unique infrared spectral features; some of the IR features are similar or common to entire classes of minerals, typically arising from similar chemical moieties or functional groups in the minerals: phosphates, sulfates, carbonates, etc. These characteristic 2 infrared bands generate the unique (or class-specific) bands that distinguish the mineral from the interferents or backgrounds. We have observed several cases where the chemical moieties that provide the

  18. Spectroscopy

    DEFF Research Database (Denmark)

    Berg, Rolf W.

    This introductory booklet covers the basics of molecular spectroscopy, infrared and Raman methods, instrumental considerations, symmetry analysis of molecules, group theory and selection rules, as well as assignments of fundamental vibrational modes in molecules.......This introductory booklet covers the basics of molecular spectroscopy, infrared and Raman methods, instrumental considerations, symmetry analysis of molecules, group theory and selection rules, as well as assignments of fundamental vibrational modes in molecules....

  19. Quantum behavior of terahertz photoconductivity in silicon nanocrystals networks

    Czech Academy of Sciences Publication Activity Database

    Pushkarev, Vladimir; Ostatnický, T.; Němec, Hynek; Chlouba, T.; Trojánek, F.; Malý, P.; Zacharias, M.; Gutsch, S.; Hiller, D.; Kužel, Petr

    2017-01-01

    Roč. 95, č. 12 (2017), s. 1-9, č. článku 125424. ISSN 2469-9950 R&D Projects: GA ČR GA17-03662S EU Projects: European Commission(XE) 607521 - NOTEDEV Institutional support: RVO:68378271 Keywords : terahertz spectroscopy * charge transport * silicon nanocrystals * linear response theory Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.) Impact factor: 3.836, year: 2016

  20. Terahertz-Radiation-Enhanced Emission of Fluorescence from Gas Plasma

    International Nuclear Information System (INIS)

    Liu Jingle; Zhang, X.-C.

    2009-01-01

    We report the study of femtosecond laser-induced air plasma fluorescence under the illumination of terahertz (THz) pulses. Semiclassical modeling and experimental verification indicate that time-resolved THz radiation-enhanced emission of fluorescence is dominated by the electron kinetics and the electron-impact excitation of gas molecules or ions. We demonstrate that the temporal waveform of the THz field could be retrieved from the transient enhanced fluorescence, making omnidirectional, coherent detection available for THz time-domain spectroscopy.

  1. Probing Ultrafast Electron Dynamics at Surfaces Using Soft X-Ray Transient Reflectivity Spectroscopy

    Science.gov (United States)

    Baker, L. Robert; Husek, Jakub; Biswas, Somnath; Cirri, Anthony

    The ability to probe electron dynamics with surface sensitivity on the ultrafast time scale is critical for understanding processes such as charge separation, injection, and surface trapping that mediate efficiency in catalytic and energy conversion materials. Toward this goal, we have developed a high harmonic generation (HHG) light source for femtosecond soft x-ray reflectivity. Using this light source we investigated the ultrafast carrier dynamics at the surface of single crystalline α-Fe2O3, polycrystalline α-Fe2O3, and the mixed metal oxide, CuFeO2. We have recently demonstrated that CuFeO2 in particular is a selective catalyst for photo-electrochemical CO2 reduction to acetate; however, the role of electronic structure and charge carrier dynamics in mediating catalytic selectivity has not been well understood. Soft x-ray reflectivity measurements probe the M2,3, edges of the 3d transition metals, which provide oxidation and spin state resolution with element specificity. In addition to chemical state specificity, these measurements are also surface sensitive, and by independently simulating the contributions of the real and imaginary components of the complex refractive index, we can differentiate between surface and sub-surface contributions to the excited state spectrum. Accordingly, this work demonstrates the ability to probe ultrafast carrier dynamics in catalytic materials with element and chemical state specificity and with surface sensitivity.

  2. Testing the Kerr Black Hole Hypothesis Using X-Ray Reflection Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Bambi, Cosimo; Nampalliwar, Sourabh [Center for Field Theory and Particle Physics and Department of Physics, Fudan University, 200433 Shanghai (China); Cárdenas-Avendaño, Alejandro [Programa de Matemática, Fundación Universitaria Konrad Lorenz, 110231 Bogotá (Colombia); Dauser, Thomas [Remeis Observatory and ECAP, Universität Erlangen-Nürnberg, D-96049 Bamberg (Germany); García, Javier A., E-mail: bambi@fudan.edu.cn [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States)

    2017-06-20

    We present the first X-ray reflection model for testing the assumption that the metric of astrophysical black holes is described by the Kerr solution. We employ the formalism of the transfer function proposed by Cunningham. The calculations of the reflection spectrum of a thin accretion disk are split into two parts: the calculation of the transfer function and the calculation of the local spectrum at any emission point in the disk. The transfer function only depends on the background metric and takes into account all the relativistic effects (gravitational redshift, Doppler boosting, and light bending). Our code computes the transfer function for a spacetime described by the Johannsen metric and can easily be extended to any stationary, axisymmetric, and asymptotically flat spacetime. Transfer functions and single line shapes in the Kerr metric are compared to those calculated from existing codes to check that we reach the necessary accuracy. We also simulate some observations with NuSTAR and LAD/eXTP and fit the data with our new model to show the potential capabilities of current and future observations to constrain possible deviations from the Kerr metric.

  3. Hygrothermal degradation of (3-glycidoxypropyl)trimethoxysilane films studied by neutron and X-ray reflectivity and attenuated total reflection infrared spectroscopy

    International Nuclear Information System (INIS)

    Tallant, David Robert; Garcia, Manuel Joseph; Majewski, Jaroslaw; Kent, Michael Stuart; Yim, Hyun

    2005-01-01

    Thin films of organosilanes have great technological importance in the areas of adhesion promotion, durability, and corrosion resistance. However, it is well-known that water can degrade organosilane films, particularly at elevated temperatures. In this work, X-ray and neutron reflectivity (XR and NR) were combined with attenuated total reflection infrared (ATR-IR) spectroscopy to study the chemical and structural changes within thin films of (3-glycidoxypropyl)trimethoxysilane (GPS) after exposure for various periods of time to air saturated with either D 2 O or H 2 O at 80 C. For NR and XR, ultrathin (∼100 (angstrom)) films were prepared by spin-coating. Both D 2 O and H 2 O provide neutron scattering contrast with GPS. Variations in the neutron scattering length density (SLD) profiles (a function of mass density and atomic composition) with conditioning time were measured after drying the samples out and also swelled with H 2 O or D 2 O vapor at room temperature. For samples that were dried out prior to measurement, little or no change was observed for H 2 O conditioning up to 3.5 days, but large changes were observed after 30 days of conditioning. The range of conditioning time for this structural change was narrowed to between 4 and 10 days with XR. The SLD profiles indicated that the top portion of the GPS film was transformed into a thick low-density layer after conditioning, but the bottom portion showed little structural change. A previous NR study of as-prepared GPS films involving swelling with deuterated nitrobenzene showed that the central portion of the film has much lower cross-link density than the region nearest the substrate. The present data show that the central portion also swells to a much greater extent with water and hydrolyzes more rapidly. The chemical degradation mechanism was identified by IR as hydrolysis of siloxane bonds. For ATR-IR, GPS films were prepared by dip-coating, which resulted in a greater and more variable thickness than

  4. Uncovering the Terahertz Spectrum of Copper Sulfate Pentahydrate.

    Science.gov (United States)

    Ruggiero, Michael T; Korter, Timothy M

    2016-01-21

    Terahertz vibrational spectroscopy has evolved into a powerful tool for the detection and characterization of transition metal sulfate compounds, specifically for its ability to differentiate between various hydrated forms with high specificity. Copper(II) sulfate is one such system where multiple crystalline hydrates have had their terahertz spectra fully assigned, and the unique spectral fingerprints of the forms allows for characterization of multicomponent systems with relative ease. Yet the most commonly occurring form, copper(II) sulfate pentahydrate (CuSO4·5H2O), has proven elusive due to the presence of a broad absorption across much of the terahertz region, making the unambiguous identification of its spectral signature difficult. Here, it is shown that the sub-100 cm(-1) spectrum of CuSO4·5H2O is obscured by absorption from adsorbed water and that controlled drying reveals sharp underlying features. The crystalline composition of the samples was monitored in parallel by X-ray diffraction as a function of drying time, supporting the spectroscopic results. Finally, the terahertz spectrum of CuSO4·5H2O was fully assigned using solid-state density functional theory simulations, helping attribute the additional absorptions that appear after excessive drying to formation of CuSO4·3H2O.

  5. Terahertz magnonics: Feasibility of using terahertz magnons for information processing

    Science.gov (United States)

    Zakeri, Khalil

    2018-06-01

    An immediate need of information technology is designing fast, small and low-loss devices. One of the ways to design such devices is using the bosonic quasiparticles, such as magnons, for information transfer/processing. This is the main idea behind the field of magnonics. When a magnon propagates through a magnetic medium, no electrical charge transport is involved and therefore no energy losses, creating Joule heating, occur. This is the most important advantage of using magnons for information transfer. Moreover the mutual conversion between magnons and the other carriers e.g. electrons, photons and plasmons shall open new opportunities to realize tunable multifunctional devices. Magnons cover a very wide range of frequency, from sub-gigahertz up to a few hundreds of terahertz. The magnon frequency has an important impact on the performance of magnon-based devices (the larger the excitation frequency, the faster the magnons). This means that the use of high-frequency (terahertz) magnons would provide a great opportunity for the design of ultrafast devices. However, up to now the focus in magnonics has been on the low-frequency gigahertz magnons. Here we discuss the feasibility of using terahertz magnons for application in magnonic devices. We shall bring the concept of terahertz magnonics into discussion. We discuss how the recently discovered phenomena in the field of terahertz magnons may inspire ideas for designing new magnonic devices. We further introduce methods to tune the fundamental properties of terahertz magnons, e.g. their eigenfrequency and lifetime.

  6. Diffuse reflectance spectroscopy for optical soft tissue differentiation as remote feedback control for tissue-specific laser surgery.

    Science.gov (United States)

    Stelzle, Florian; Tangermann-Gerk, Katja; Adler, Werner; Zam, Azhar; Schmidt, Michael; Douplik, Alexandre; Nkenke, Emeka

    2010-04-01

    Laser surgery does not provide haptic feedback for operating layer-by-layer and thereby preserving vulnerable anatomical structures like nerve tissue or blood vessels. Diffuse reflectance spectra can facilitate remote optical tissue differentiation. It is the aim of the study to use this technique on soft tissue samples, to set a technological basis for a remote optical feedback system for tissue-specific laser surgery. Diffuse reflectance spectra (wavelength range: 350-650 nm) of ex vivo types of soft tissue (a total of 10,800 spectra) of the midfacial region of domestic pigs were remotely measured under reduced environmental light conditions and analyzed in order to differentiate between skin, mucosa, muscle, subcutaneous fat, and nerve tissue. We performed a principal components (PC) analysis (PCA) to reduce the number of variables. Linear discriminant analysis (LDA) was utilized for classification. For the tissue differentiation, we calculated the specificity and sensitivity by receiver operating characteristic (ROC) analysis and the area under curve (AUC). Six PCs were found to be adequate for tissue differentiation with diffuse reflectance spectra using LDA. All of the types of soft tissue could be differentiated with high specificity and sensitivity. Only the tissue pairs nervous tissue/fatty tissue and nervous tissue/mucosa showed a decline of differentiation due to bio-structural similarity. However, both of these tissue pairs could still be differentiated with a specificity and sensitivity of more than 90%. Analyzing diffuse reflectance spectroscopy with PCA and LDA allows for remote differentiation of biological tissue. Considering the limitations of the ex vivo conditions, the obtained results are promising and set a basis for the further development of a feedback system for tissue-specific laser surgery. (c) 2010 Wiley-Liss, Inc.

  7. Portable (handheld) clinical device for quantitative spectroscopy of skin, utilizing spatial frequency domain reflectance techniques

    Science.gov (United States)

    Saager, Rolf B.; Dang, An N.; Huang, Samantha S.; Kelly, Kristen M.; Durkin, Anthony J.

    2017-09-01

    Spatial Frequency Domain Spectroscopy (SFDS) is a technique for quantifying in-vivo tissue optical properties. SFDS employs structured light patterns that are projected onto tissues using a spatial light modulator, such as a digital micromirror device. In combination with appropriate models of light propagation, this technique can be used to quantify tissue optical properties (absorption, μa, and scattering, μs', coefficients) and chromophore concentrations. Here we present a handheld implementation of an SFDS device that employs line (one dimensional) imaging. This instrument can measure 1088 spatial locations that span a 3 cm line as opposed to our original benchtop SFDS system that only collects a single 1 mm diameter spot. This imager, however, retains the spectral resolution (˜1 nm) and range (450-1000 nm) of our original benchtop SFDS device. In the context of homogeneous turbid media, we demonstrate that this new system matches the spectral response of our original system to within 1% across a typical range of spatial frequencies (0-0.35 mm-1). With the new form factor, the device has tremendously improved mobility and portability, allowing for greater ease of use in a clinical setting. A smaller size also enables access to different tissue locations, which increases the flexibility of the device. The design of this portable system not only enables SFDS to be used in clinical settings but also enables visualization of properties of layered tissues such as skin.

  8. Photothermal microfluidic cantilever deflection spectroscopy reflecting clustering mechanism of ethanol water mixtures

    Science.gov (United States)

    Ghoraishi, Maryam; Hawk, John; Thundat, Thomas

    Aqueous mixture of alcohol is a typical prototype for biomolecules, micelle formation, and structural stability of proteins. Therefore, Short chain alcohols such as EtOH have been used as a simple model for understanding of more complex aqueous biomolecules. Here we study vibrational energy peaks of EtOH water binary mixtures using micromechanical calorimetric spectroscopy using bimaterial microfluidic cantilevers (BMC). The IR spectra of EtOH-water are experimentally collected employing a BMC as concentration of EtOH changes from 20-100 wt%. As concentration of EtOH varies in the mixture, considerable shifts in the wavenumber at IR absorption peak maxima are reported. The experimentally measured shifts in the wavenumber at IR absorption peak maxima are related to changes in dipole moment (μ) of EtOH at different concentration. The relationship between IR absorption wavenumber for both anti and gauche conformers of EtOH, and inverse dipole moment, 1/ μ, of EtOH at different concentrations follows a power law dependence. Our technique offers a platform to investigate dipole effect on molecular vibrations of mixtures in confined picoliter volumes, previously unexplored with other analytical techniques due to limitations of volume under study.

  9. Differentiation of Apple Varieties and Investigation of Organic Status Using Portable Visible Range Reflectance Spectroscopy

    Directory of Open Access Journals (Sweden)

    Jordan Vincent

    2018-05-01

    Full Text Available Food fraud, the sale of goods that have in some way been mislabelled or tampered with, is an increasing concern, with a number of high profile documented incidents in recent years. These recent incidents and their scope show that there are gaps in the food chain where food authentication methods are not applied or otherwise not sufficient and more accessible detection methods would be beneficial. This paper investigates the utility of affordable and portable visible range spectroscopy hardware with partial least squares discriminant analysis (PLS-DA when applied to the differentiation of apple types and organic status. This method has the advantage that it is accessible throughout the supply chain, including at the consumer level. Scans were acquired of 132 apples of three types, half of which are organic and the remaining non-organic. The scans were preprocessed with zero correction, normalisation and smoothing. Two tests were used to determine accuracy, the first using 10-fold cross-validation and the second using a test set collected in different ambient conditions. Overall, the system achieved an accuracy of 94% when predicting the type of apple and 66% when predicting the organic status. Additionally, the resulting models were analysed to find the regions of the spectrum that had the most significance. Then, the accuracy when using three-channel information (RGB is presented and shows the improvement provided by spectroscopic data.

  10. Differentiation of Apple Varieties and Investigation of Organic Status Using Portable Visible Range Reflectance Spectroscopy.

    Science.gov (United States)

    Vincent, Jordan; Wang, Hui; Nibouche, Omar; Maguire, Paul

    2018-05-25

    Food fraud, the sale of goods that have in some way been mislabelled or tampered with, is an increasing concern, with a number of high profile documented incidents in recent years. These recent incidents and their scope show that there are gaps in the food chain where food authentication methods are not applied or otherwise not sufficient and more accessible detection methods would be beneficial. This paper investigates the utility of affordable and portable visible range spectroscopy hardware with partial least squares discriminant analysis (PLS-DA) when applied to the differentiation of apple types and organic status. This method has the advantage that it is accessible throughout the supply chain, including at the consumer level. Scans were acquired of 132 apples of three types, half of which are organic and the remaining non-organic. The scans were preprocessed with zero correction, normalisation and smoothing. Two tests were used to determine accuracy, the first using 10-fold cross-validation and the second using a test set collected in different ambient conditions. Overall, the system achieved an accuracy of 94% when predicting the type of apple and 66% when predicting the organic status. Additionally, the resulting models were analysed to find the regions of the spectrum that had the most significance. Then, the accuracy when using three-channel information (RGB) is presented and shows the improvement provided by spectroscopic data.

  11. Reflectance spectroscopy is an effective tool for monitoring soot pollution in an urban suburb.

    Science.gov (United States)

    Saaroni, H; Chudnovsky, A; Ben-Dor, E

    2010-02-01

    This study examines whether converting the fossil fuel of the Tel Aviv power station from oil to gas influences air pollution in the local urban environment. To this end, the spectral properties of accumulated dust on tree leaves and paper bags were assessed before (2004) and after (2006) the conversion. The sampling site was a garden in a neighborhood located 2700m downwind of the power station. In addition, air pollution concentrations and particulate matter parameters recorded by a local meteorological station were analyzed (PM(10), NO(x), NO(2), NO, and SO(2)). Although differences in the average monthly concentration of pollution parameters are mostly insignificant between the two periods, the accumulated particulate matter exhibits considerably different spectral patterns. All first period samples exhibit a distinctly concave slope in the spectral region between 400 and 1400nm, indicative of high amounts of soot, most likely due to the combustion products of fuel oil exhausted by the power plant. In contrast, the second period samples exhibit spectra that indicate reduced soot content and even appear slightly convex, evidencing the presence of dust of mineral origin, a feature likely masked by the soot in the first period. Thus, the spectral data support that the power plant conversion results in less pollution. More generally, this study corroborates that VIS-NIR-SWIR spectroscopy characterizes key properties of the particulate layer accumulating on sampled surfaces and thus, is a powerful method for monitoring the urban environment. Copyright 2009 Elsevier B.V. All rights reserved.

  12. Diffuse Reflectance Spectroscopy: Getting the Capillary Refill Test Under One's Thumb.

    Science.gov (United States)

    Henricson, Joakim; Toll John, Rani; Anderson, Chris D; Björk Wilhelms, Daniel

    2017-12-02

    The capillary refill test was introduced in 1947 to help estimate circulatory status in critically ill patients. Guidelines commonly state that refill should occur within 2 s after releasing 5 s of firm pressure (e.g., by the physician's finger) in the normal healthy supine patient. A slower refill time indicates poor skin perfusion, which can be caused by conditions including sepsis, blood loss, hypoperfusion, and hypothermia. Since its introduction, the clinical usefulness of the test has been debated. Advocates point out its feasibility and simplicity and claim that it can indicate changes in vascular status earlier than changes in vital signs such as heart rate. Critics, on the other hand, stress that the lack of standardization in how the test is performed and the highly subjective nature of the naked eye assessment, as well as the test's susceptibility to ambient factors, markedly lowers the clinical value. The aim of the present work is to describe in detail the course of the refill event and to suggest potentially more objective and exact endpoint values for the capillary refill test using diffuse polarization spectroscopy.

  13. Characterizing and Authenticating Montilla-Moriles PDO Vinegars Using Near Infrared Reflectance Spectroscopy (NIRS Technology

    Directory of Open Access Journals (Sweden)

    María-José De la Haba

    2014-02-01

    Full Text Available This study assessed the potential of near infrared (NIR spectroscopy as a non-destructive method for characterizing Protected Designation of Origin (PDO “Vinagres de Montilla-Moriles” wine vinegars and for classifying them as a function of the manufacturing process used. Three spectrophotometers were evaluated for this purpose: two monochromator instruments (Foss NIRSystems 6500 SY-I and Foss NIRSystems 6500 SY-II; spectral range 400–2,500 nm in both cases and a diode-array instrument (Corona 45 VIS/NIR; spectral range 380–1,700 nm. A total of 70 samples were used to predict major chemical quality parameters (total acidity, fixed acidity, volatile acidity, pH, dry extract, ash, acetoin, methanol, total polyphenols, color (tonality and intensity, and alcohol content, and to construct models for the classification of vinegars as a function of the manufacturing method used. The results obtained indicate that this non-invasive technology can be used successfully by the vinegar industry and by PDO regulators for the routine analysis of vinegars in order to authenticate them and to detect potential fraud. Slightly better results were achieved with the two monochromator instruments. The findings also highlight the potential of these NIR instruments for predicting the manufacturing process used, this being of particular value for the industrial authentication of traditional wine vinegars.

  14. Infrared reflection absorption spectroscopy study of radiation-heterogeneous processes in the system of aluminum-hexane

    International Nuclear Information System (INIS)

    Gadzhieva, N.N.; Rimikhanova, A.N.; Garibov, A.A.

    2004-01-01

    Full text: Infrared reflection absorption spectroscopy (IRRAS) was applied to study the regularities of radiation conversion of hexane on the surface of aluminum. The research object was the thin polished aluminum plate by mark of AD-00 with reflection coefficient R=0.8†0.85 in infrared range λ=2.2†15 μ . As adsorbate unsaturated vapors of spectroscopy clear hexane were used. The absorption of hexane (C 2 H 14 ) was being studied manometric at pressures P=(0.1†1.0)·10 2 Pa , what corresponded to monolayer value of 1-10. The samples were irradiated with γ-quanta of 60 Co with D=1.03 Gy·s -1 doze rate. Infrared reflection spectrum when linear-polarized radiation fall on the sample under angle ψ=10 o was measured by spectrophotometer 'Specord 71 JR' in diapason of 4000-650cm -1 at the temperature by mean of special reflecting arrangements. Formation of molecular hydrogen (H 2 ) and other gaseous products of decomposition were controlled by chromotographical and infrared spectroscopical methods. The analysis of hexane infrared absorption spectra after radiation-stimulated adsorption on the surface of aluminum, points out the formation of H-bonded hydrocarbon complex ( ν∼2680cm -1 ) with much loosening of C-H bond (the molecular form of absorption) and the possibility of proceeding dissociative absorption with formation of metal-alkyls (ν∼2880, 2920, 2970 cm -1 ). Probability of the last mentioned process, which proceeds in the most defective centers, increases with increasing of γ-radiation doze. It was established that the radiation processes in hetero system Al-ads.C 6 H 14 accelerate the radiolysis of hexane. At all these the radiation decomposition of hexane in hetero system Al-ads.C 6 H 14 is accompanied by formation the surface hydrides (ν∼1700-2000 cm -1 ), acetylene (ν∼3200-3300 cm -1 ), ethylene (ν∼980 cm -1 ), and also gaseous products of molecular hydrogen decomposition (H 2 ) and hydrocarbons C 1 -C 5 (bands with maxima 770, 790

  15. Diffuse Reflectance Spectroscopy of Hidden Objects. Part II: Recovery of a Target Spectrum.

    Science.gov (United States)

    Pomerantsev, Alexey L; Rodionova, Oxana Ye; Skvortsov, Alexej N

    2017-08-01

    In this study, we consider the reconstruction of a diffuse reflectance near-infrared spectrum of an object (target spectrum) in case the object is covered by an interfering absorbing and scattering layer. Recovery is performed using a new empirical method, which was developed in our previous study. We focus on a system, which consists of several layers of polyethylene (PE) film and underlayer objects with different spectral features. The spectral contribution of the interfering layer is modeled by a three-component two-parameter multivariate curve resolution (MCR) model, which was built and calibrated using spectrally flat objects. We show that this model is applicable to real objects with non-uniform spectra. Ultimately, the target spectrum can be reconstructed from a single spectrum of the covered target. With calculation methods, we are able to recover quite accurately the spectrum of a target even when the object is covered by 0.7 mm of PE.

  16. Rapid determination of ions by combined solid-phase extraction--diffuse reflectance spectroscopy

    Science.gov (United States)

    Fritz, James S.; Arena, Matteo P.; Steiner, Steven A.; Porter, Marc D.

    2003-01-01

    We introduce colorimetric solid-phase extraction (C-SPE) for the rapid determination of selected ions. This new technique links the exhaustive concentration of an analyte by SPE onto a membrane disk surface for quantitative measurement with a hand-held diffuse reflectance spectrometer. The concentration/measurement procedure is complete in approximately 1 min and can be performed almost anywhere. This method has been used to monitor iodine and iodide in spacecraft water in the 0.1-5.0 ppm range and silver(I) in the range of 5.0-1000 microg/l. Applications to the trace analysis of copper(II), nickel(II), iron(III) and chromium(VI) are described. Studies on the mechanism of extraction showed that impregnation of the disk with a surfactant as well as a complexing reagent results in uptake of additional water, which markedly improves the extraction efficiency.

  17. Spectroelectrochemical study of polyphenylene by in situ external reflection FT-IR spectroscopy. Pt. 2

    International Nuclear Information System (INIS)

    Kvarnstroem, C.; Ivaska, A.

    1994-01-01

    In situ external reflection FT-IR measurements are performed during cyclic voltammetric scans on electrochemically polymerized polyphenylene films. The films are polymerized either in 0.1 or 0.8 M biphenyl in 0.1 M TBABF 4 in acetonitrile. Changes in the IR spectrum of films of different thicknesses are studied when the films are potentially cycled from the neutral to the oxidized states of the polymer. No differences between films made in high or low dimer concentration can be observed in the spectra. The potential-dependent insertion and expulsion of solvent, residual water, anions and cations in and out of the film have different behaviour in films of different thicknesses. Changes in the structure of the segments in the film, from the benzenoid form into the quinoid form, can be followed. Differences between the first and subsequent cyclic potential scans are observed. (orig.)

  18. Observation of neutron standing waves at total reflection by precision gamma spectroscopy

    International Nuclear Information System (INIS)

    Aksenov, V.L.; Gundorin, N.A.; Nikitenko, Yu.V.; Popov, Yu.P.; Cser, L.

    1998-01-01

    Total reflection of polarized neutrons from the layered structure glass/Fe (1000 A Angstrom)/Gd (50 A Angstrom) is investigated by registering neutrons and gamma-quanta from thermal neutron capture. The polarization ratio of gamma counts of neutron beams polarized in and opposite the direction of the magnetic field is measured. The polarization ratio is larger than unity for the neutron wavelengths λ 2.2 A Angstrom. Such behaviour of the wavelength dependence of the gamma-quanta polarization ratio points to the fact that over the surface of the Fe Layer a neutron standing wave caused by the interference of the incident neutron wave and the wave refracted from the magnetized Fe layer is formed

  19. Plasma Wave Electronic Terahertz Technology

    National Research Council Canada - National Science Library

    Shur, Michael

    2003-01-01

    Plasma waves are oscillations of electron density in time and space. In deep submicron field effect transistors plasma wave frequencies lie in the terahertz range and can be tuned by applied gate bias...

  20. Application of attenuated total reflectance Fourier transform infrared spectroscopy for determination of cefixime in oral pharmaceutical formulations.

    Science.gov (United States)

    Kandhro, Aftab A; Laghari, Abdul Hafeez; Mahesar, Sarfaraz A; Saleem, Rubina; Nelofar, Aisha; Khan, Salman Tariq; Sherazi, S T H

    2013-11-01

    A quick and reliable analytical method for the quantitative assessment of cefixime in orally administered pharmaceutical formulations is developed by using diamond cell attenuated total reflectance (ATR) Fourier transform infrared (FT-IR) spectroscopy as an easy procedure for quality control laboratories. The standards for calibration were prepared in aqueous medium ranging from 350 to 6000mg/kg. The calibration model was developed based on partial least square (PLS) using finger print region of FT-IR spectrum in the range from 1485 to 887cm(-1). Excellent coefficient of determination (R(2)) was achieved as high as 0.99976 with root mean square error of 44.8 for calibration. The application of diamond cell (smart accessory) ATR FT-IR proves a reliable determination of cefixime in pharmaceutical formulations to assess the quality of the final product. Copyright © 2013 Elsevier B.V. All rights reserved.