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Sample records for spinning spectroscopic technique

  1. Spectroscopic studies of UV irradiated erythrosine B thin films prepared by spin coating technique.

    PubMed

    Zeyada, H M; El-Mallah, H M; Atwee, T; El-Damhogi, D G

    2017-05-15

    The spectroscopic studies of erythrosine B thin films manufactured by the spin coating technique have been presented. The spectra of infrared absorption allow characterization of vibrational modes for erythrosine B in powder form, pristine and UV irradiated thin films. The absorption spectra recorded in UV-vis-NIR for pristine films of erythrosine B display two main bands. UV irradiation on erythrosine B films decreased absorbance over the spectra. Indirect allowed transition with optical energy gap of 2.57eV is observed in pristine films. UV irradiation introduced structural defects and decreased optical band gap. Some of the optical absorption parameters and their relation to UV irradiation times, namely molar extinction coefficient (ε), electronic dipole strength (q(2)), and oscillator strength (f), of the principal optical transitions have also been evaluated.

  2. A Comparison of Galaxy Counting Techniques in Spectroscopically Undersampled Regions

    NASA Astrophysics Data System (ADS)

    Specian, Mike A.; Szalay, Alex S.

    2016-11-01

    Accurate measures of galactic overdensities are invaluable for precision cosmology. Obtaining these measurements is complicated when members of one’s galaxy sample lack radial depths, most commonly derived via spectroscopic redshifts. In this paper, we utilize the Sloan Digital Sky Survey’s Main Galaxy Sample to compare seven methods of counting galaxies in cells when many of those galaxies lack redshifts. These methods fall into three categories: assigning galaxies discrete redshifts, scaling the numbers counted using regions’ spectroscopic completeness properties, and employing probabilistic techniques. We split spectroscopically undersampled regions into three types—those inside the spectroscopic footprint, those outside but adjacent to it, and those distant from it. Through Monte Carlo simulations, we demonstrate that the preferred counting techniques are a function of region type, cell size, and redshift. We conclude by reporting optimal counting strategies under a variety of conditions.

  3. Spectroscopic Measurement Techniques for Aerospace Flows

    NASA Technical Reports Server (NTRS)

    Danehy, Paul M.; Bathel, Brett F.; Johansen, Craig T.; Cutler, Andrew D.; Hurley, Samantha

    2014-01-01

    The conditions that characterize aerospace flows are so varied, that a single diagnostic technique is not sufficient for its measurement. Fluid dynamists use knowledge of similarity to help categorize and focus on different flow conditions. For example, the Reynolds number represents the ratio of inertial to viscous forces in a flow. When the velocity scales, length scales, and gas density are large and the magnitude of the molecular viscosity is low, the Reynolds number becomes large. This corresponds to large scale vehicles (e.g Airbus A380), fast moving objects (e.g. artillery projectiles), vehicles in dense fluids (e.g. submarine in water), or flows with low dynamic viscosity (e.g. skydiver in air). In each of these cases, the inertial forces dominate viscous forces, and unsteady turbulent fluctuations in the flow variables are observed. In contrast, flows with small length scales (e.g. dispersion of micro-particles in a solid rocket nozzle), slow moving objects (e.g. micro aerial vehicles), flows with low density gases (e.g. atmospheric re-entry), or fluids with a large magnitude of viscosity (e.g. engine coolant flow), all have low Reynolds numbers. In these cases, viscous forces become very important and often the flows can be steady and laminar. The Mach number, which is the ratio of the velocity to the speed of sound in the medium, also helps to differentiate types of flows. At very low Mach numbers, acoustic waves travel much faster than the object, and the flow can be assumed to be incompressible (e.g. Cessna 172 aircraft). As the object speed approaches the speed of sound, the gas density can become variable (e.g. flow over wing of Learjet 85). When the object speed is higher than the speed of sound (Ma > 1), the presences of shock waves and other gas dynamic features can become important to the vehicle performance (e.g. SR-71 Blackbird). In the hypersonic flow regime (Ma > 5), large changes in temperature begin to affect flow properties, causing real

  4. Evaluation of Her2 status using photoacoustic spectroscopic CT techniques

    NASA Astrophysics Data System (ADS)

    Shaffer, Michael; Kruger, Robert; Reinecke, Daniel; Chin-Sinex, Helen; Mendonca, Marc; Stantz, Keith M.

    2010-02-01

    Purpose: The purpose of this study is to determine the feasibility of using photacoustic CT spectroscopy(PCT-s) to track a near infrared dye conjugated with trastuzumab in vivo. Materials and Methods: An animal model was developed which contained both high and low Her2 expression tumor xenografts on the same mouse. The tumors were imaged at multiple wavelengths (680- 950nm) in the PCT scanner one day prior to injection of the near infrared conjugated probe. Baseline optical imaging data was acquired and the probe was then injected via the tail vein. Fluorescence data was acquired over the next week, PCT spectroscopic data was also acquired during this timeframe. The mice were sacrificed and tumors were extirpated and sent to pathology for IHC staining to verify Her2 expression levels. The optical fluorescence images were analyzed to determine probe uptake dynamics. Reconstructed PCT spectroscopic data was analyzed using IDL routines to deconvolve the probe signal from endogenous background signals, and to determine oxygen saturation. Results: The location of the NIR conjugate was able to be identified within the tumor utilizing IDL fitting routines, in addition oxygen saturation, and hemoglobin concentrations were discernible from the spectroscopic data. Conclusion: Photacoustic spectroscopy allows for the determination of in vivo tumor drug delivery at greater depths than can be determined from optical imaging techniques.

  5. Synthesis and spectroscopic characterization of high-spin mononuclear iron(II) p-semiquinonate complexes.

    PubMed

    Baum, Amanda E; Park, Heaweon; Lindeman, Sergey V; Fiedler, Adam T

    2014-12-01

    Two mononuclear iron(II) p-semiquinonate (pSQ) complexes have been generated via one-electron reduction of precursor complexes containing a substituted 1,4-naphthoquinone ligand. Detailed spectroscopic and computational analysis confirmed the presence of a coordinated pSQ radical ferromagnetically coupled to the high-spin Fe(II) center. The complexes are intended to model electronic interactions between (semi)quinone and iron cofactors in biology.

  6. Application of optical spectroscopic techniques for disease diagnosis

    NASA Astrophysics Data System (ADS)

    Saha, Anushree

    Optical spectroscopy, a truly non-invasive tool for remote diagnostics, is capable of providing valuable information on the structure and function of molecules. However, most spectroscopic techniques suffer from drawbacks, which limit their application. As a part of my dissertation work, I have developed theoretical and experimental methods to address the above mentioned issues. I have successfully applied these methods for monitoring the physical, chemical and biochemical parameters of biomolecules involved in some specific life threatening diseases like lead poisoning and age-related macular degeneration (AMD). I presented optical studies of melanosomes, which are one of the vital organelles in the human eye, also known to be responsible for a disease called age-related macular degeneration (AMD), a condition of advanced degeneration which causes progressive blindness. I used Raman spectroscopy, to first chemically identify the composition of melanosome, and then monitor the changes in its functional and chemical behavior due to long term exposure to visible light. The above study, apart from explaining the role of melanosomes in AMD, also sets the threshold power for lasers used in surgeries and other clinical applications. In the second part of my dissertation, a battery of spectroscopic techniques was successfully applied to explore the different binding sites of lead ions with the most abundant carrier protein molecule in our circulatory system, human serum albumin. I applied optical spectroscopic tools for ultrasensitive detection of heavy metal ions in solution which can also be used for lead detection at a very early stage of lead poisoning. Apart from this, I used Raman microspectroscopy to study the chemical alteration occurring inside a prostate cancer cell as a result of a treatment with a low concentrated aqueous extract of a prospective drug, Nerium Oleander. The experimental methods used in this study has tremendous potential for clinical

  7. New Developments of Broadband Cavity Enhanced Spectroscopic Techniques

    NASA Astrophysics Data System (ADS)

    Walsh, A.; Zhao, D.; Linnartz, H.; Ubachs, W.

    2013-06-01

    In recent years, cavity enhanced spectroscopic techniques, such as cavity ring-down spectroscopy (CRDS), cavity enhanced absorption spectroscopy (CEAS), and broadband cavity enhanced absorption spectroscopy (BBCEAS), have been widely employed as ultra-sensitive methods for the measurement of weak absorptions and in the real-time detection of trace species. In this contribution, we introduce two new cavity enhanced spectroscopic concepts: a) Optomechanical shutter modulated BBCEAS, a variant of BBCEAS capable of measuring optical absorption in pulsed systems with typically low duty cycles. In conventional BBCEAS applications, the latter substantially reduces the signal-to-noise ratio (S/N), consequently also reducing the detection sensitivity. To overcome this, we incorporate a fast optomechanical shutter as a time gate, modulating the detection scheme of BBCEAS and increasing the effective duty cycle reaches a value close to unity. This extends the applications of BBCEAS into pulsed samples and also in time-resolved studies. b) Cavity enhanced self-absorption spectroscopy (CESAS), a new spectroscopic concept capable of studying light emitting matter (plasma, flames, combustion samples) simultaneously in absorption and emission. In CESAS, a sample (plasma, flame or combustion source) is located in an optically stable cavity consisting of two high reflectivity mirrors, and here it acts both as light source and absorbing medium. A high detection sensitivity of weak absorption is reached without the need of an external light source, such as a laser or broadband lamp. The performance is illustrated by the first CESAS result on a supersonically expanding hydrocarbon plasma. We expect CESAS to become a generally applicable analytical tool for real time and in situ diagnostics. A. Walsh, D. Zhao, W. Ubachs, H. Linnartz, J. Phys. Chem. A, {dx.doi.org/10.1021/jp310392n}, in press, 2013. A. Walsh, D. Zhao, H. Linnartz Rev. Sci. Instrum. {84}(2), 021608 2013. A. Walsh, D. Zhao

  8. Rapid identification of single microbes by various Raman spectroscopic techniques

    NASA Astrophysics Data System (ADS)

    Rösch, Petra; Harz, Michaela; Schmitt, Michael; Peschke, Klaus-Dieter; Ronneberger, Olaf; Burkhardt, Hans; Motzkus, Hans-Walter; Lankers, Markus; Hofer, Stefan; Thiele, Hans; Popp, Jürgen

    2006-02-01

    A fast and unambiguous identification of microorganisms is necessary not only for medical purposes but also in technical processes such as the production of pharmaceuticals. Conventional microbiological identification methods are based on the morphology and the ability of microbes to grow under different conditions on various cultivation media depending on their biochemical properties. These methods require pure cultures which need cultivation of at least 6 h but normally much longer. Recently also additional methods to identify bacteria are established e.g. mass spectroscopy, polymerase chain reaction (PCR), flow cytometry or fluorescence spectroscopy. Alternative approaches for the identification of microorganisms are vibrational spectroscopic techniques. With Raman spectroscopy a spectroscopic fingerprint of the microorganisms can be achieved. Using UV-resonance Raman spectroscopy (UVRR) macromolecules like DNA/RNA and proteins are resonantly enhanced. With an excitation wavelength of e.g. 244 nm it is possible to determine the ratio of guanine/cytosine to all DNA bases which allows a genotypic identification of microorganisms. The application of UVRR requires a large amount of microorganisms (> 10 6 cells) e.g. at least a micro colony. For the analysis of single cells micro-Raman spectroscopy with an excitation wavelength of 532 nm can be used. Here, the obtained information is from all type of molecules inside the cells which lead to a chemotaxonomic identification. In this contribution we show how wavelength dependent Raman spectroscopy yields significant molecular information applicable for the identification of microorganisms on a single cell level.

  9. Magnetic resonance spectroscopy editing techniques of coupled spin systems at high field

    NASA Astrophysics Data System (ADS)

    Snyder, Jeff

    Magnetic resonance spectroscopy (MRS) provides a non-invasive tool for investigating chemical concentrations in the human brain. The detection of metabolites is useful in understanding functional pathways in healthy and diseased states. Many important metabolites are composed of multiple interacting spins coupled through chemical bonds in the molecule. Whereas the observation of strong uncoupled (singlet) resonances is straightforward, complex coupling patterns and signal overlap often hinder the detection of coupled spin systems, rendering quantification problematic. One of the primary goals of this project is to investigate spectral editing techniques to detect coupled spin systems and provide a means for increasing the accuracy of quantification. A new method of spectral editing based on subtraction spectroscopy is proposed, which relies on signal differences at constant echo time (TE) produced by varying the inter-pulse delays in an asymmetric PRESS sequence. The method requires no spectrally selective pulses or multiple quantum filters, and can be easily implemented with a standard PRESS sequence. All non-varying spectral information is maintained, in contrast to other popular editing techniques. In terms of strongly coupled spin systems, the procedure is demonstrated for glutamate and glutamine discrimination, as well as simulated optimization of field strength for detection of several strongly coupled metabolites. To produce the necessary TE space variations for weakly coupled systems, the flip angle of the second refocusing pulse was varied. This technique was applied for the detection of gamma-aminobutyric acid, which is completely obscured at standard clinical field strengths. A second editing method investigated the optimization of PRESS timing parameters at multiple field strengths for the simultaneous detection of glutamate and glutamine in vivo, by maximizing the signal yield and minimizing the significant overlap at lower field strengths. Finally

  10. The VLT-FLAMES Tarantula Survey. XXI. Stellar spin rates of O-type spectroscopic binaries

    NASA Astrophysics Data System (ADS)

    Ramírez-Agudelo, O. H.; Sana, H.; de Mink, S. E.; Hénault-Brunet, V.; de Koter, A.; Langer, N.; Tramper, F.; Gräfener, G.; Evans, C. J.; Vink, J. S.; Dufton, P. L.; Taylor, W. D.

    2015-08-01

    Context. The initial distribution of spin rates of massive stars is a fingerprint of their elusive formation process. It also sets a key initial condition for stellar evolution and is thus an important ingredient in stellar population synthesis. So far, most studies have focused on single stars. Most O stars are, however, found in multiple systems. Aims: By establishing the spin-rate distribution of a sizeable sample of O-type spectroscopic binaries and by comparing the distributions of binary subpopulations with one another and with that of presumed-single stars in the same region, we aim to constrain the initial spin distribution of O stars in binaries, and to identify signatures of the physical mechanisms that affect the evolution of the spin rates of massive stars. Methods: We use ground-based optical spectroscopy obtained in the framework of the VLT-FLAMES Tarantula Survey (VFTS) to establish the projected equatorial rotational velocities (νesini) for components of 114 spectroscopic binaries in 30 Doradus. The νesini values are derived from the full width at half maximum (FWHM) of a set of spectral lines, using a FWHM vs. νesini calibration that we derive based on previous line analysis methods applied to single O-type stars in the VFTS sample. Results: The overall νesini distribution of the primary stars resembles that of single O-type stars in the VFTS, featuring a low-velocity peak (at νesini< 200 kms-1) and a shoulder at intermediate velocities (200 < νesini< 300 kms-1). The distributions of binaries and single stars, however, differ in two ways. First, the main peak at νesini ~ 100kms-1 is broader and slightly shifted towards higher spin rates in the binary distribution than that of the presumed-single stars. This shift is mostly due to short-period binaries (Porb~< 10 d). Second, the νesini distribution of primaries lacks a significant population of stars spinning faster than 300 kms-1, while such a population is clearly present in the single

  11. Terahertz imaging of metastatic lymph nodes using spectroscopic integration technique

    PubMed Central

    Park, Jae Yeon; Choi, Hyuck Jae; Cheon, Hwayeong; Cho, Seong Whi; Lee, Seungkoo; Son, Joo-Hiuk

    2017-01-01

    Terahertz (THz) imaging was used to differentiate the metastatic states of frozen lymph nodes (LNs) by using spectroscopic integration technique (SIT). The metastatic states were classified into three groups: healthy LNs, completely metastatic LNs, and partially metastatic LNs, which were obtained from three mice without infection and six mice infected with murine melanoma cells for 30 days and 15 days, respectively. Under histological examination, the healthy LNs and completely metastatic LNs were found to have a homogeneous cellular structure but the partially metastatic LNs had interfaces of the melanoma and healthy tissue. THz signals between the experimental groups were not distinguished at room temperature due to high attenuation by water in the tissues. However, a signal gap between the healthy and completely metastatic LNs was detected at freezing temperature. The signal gap could be enhanced by using SIT that is a signal processing method dichotomizing the signal difference between the healthy cells and melanoma cells with their normalized spectral integration. This technique clearly imaged the interfaces in the partially metastatic LNs, which could not be achieved by existing methods using a peak point or spectral value. The image resolution was high enough to recognize a metastatic area of about 0.7 mm size in the partially metastatic LNs. Therefore, this pilot study demonstrated that THz imaging of the frozen specimen using SIT can be used to diagnose the metastatic state of LNs for clinical application. PMID:28271007

  12. Raman spectroscopic study of the frustrated spin 1/2 antiferromagnet clinoatacamite

    NASA Astrophysics Data System (ADS)

    Liu, Xiao-Dong; Zheng, Xu-Guang; Meng, Dong-Dong; Xu, Xing-Liang; Guo, Qi-Xin

    2013-06-01

    Raman spectroscopy is a valuable and complementary tool for studying geometrically frustrated magnetic systems due to the intrinsic spin-phonon coupling. Here, we report on a Raman spectroscopic study of the geometrically frustrated spin 1/2 antiferromagnet microcrystalline clinoatacamite Cu2(OH)3Cl, focusing on the anomalous transition into the intermediate phase at Tc1 = 18.1 K. By measuring the temperature-dependent (295-4 K) full spectral profiles and main representative modes in spectral regions from 4000 to 95 cm-1, we observed probable signatures of successive magnetic transitions near Tc1 = 18 K and Tc2 = 6.4 K in the Raman band frequencies and peak widths of the representative modes. Further, we observed a pronounced Raman spectroscopy background featuring a broad continuum at all temperatures. A quantitative analysis reveals that spin fluctuations may exist on a picosecond time scale in the intermediate phase. The short time scale falls out of the μSR time window; therefore, in the intermediate phase, the μSR study as reported in (2005 Phys. Rev. Lett. 95 057201) apparently only probed the local field of the ordered spins but overlooked the quickly fluctuating ones. This is likely to give a reasonable explanation of the fact that only a small entropy release occurs at Tc1 = 18 K although a long-range order is formed.

  13. New Techniques for the Next Far Ultraviolet Spectroscopic Mission

    NASA Technical Reports Server (NTRS)

    Green, James C.; Wilkinson, Erik

    2005-01-01

    The Far Ultraviolet Spectroscopic Explorer (FUSE) has been a great success, and has addressed many critical scientific questions (Moos, et al, 2000). However, it has also highlighted the need for even more powerful instrumentation in the 900- 1200 A, regime. In particular, significantly increased effective area will permit the pursuit of additional scientific programs currently impractical or impossible with FUSE. It is unlikely that FUSE will last more than a few more years. Nor is it likely that any large scale UV-optical follow-on to HST (such as SUVO) will include the 900-1200 A, bandpass. However, FUSE remains well oversubscribed and continues to perform excellent science. Therefore, a MIDEX class mission in the next 4-6 years that could significantly improve on the FUSE capabilities would be a powerful scientific tool that would be of great utility to the astronomical community. It would open up new scientific programs if it can improve on the sensitivity of FUSE by an order of magnitude. We have identified a powerful technique for efficient, high-resolution spectroscopy in the FUV (and possibly the EUV) that may provide exactly what is needed for such a mission To achieve a factor of 10 improvement in effective area, we propose using a large (meter class), low-cost, grazing incidence metal optics. This would produced in a manner similar to the EUVE mirrors (Green, et al, 1986), using diamond turning to create the optical figure followed by uncontrolled polishing to achieve a high quality surface. This process will introduce significant figure errors that will degrade the image quality. However, if a holographic grating is employed, which has utilized the actual telescope in the recording geometry, all wavefront errors will be automatically corrected in the end-to-end spectrometer, and high quality spectroscopy will be possible with low quality (and low-cost) optics. In this way a MIDEX class FUSE can be proposed with 10 times the effective area of the

  14. Spectroscopic and computational studies of spin states of iron(IV) nitrido and imido complexes

    DOE PAGES

    Bucinsky, Lukas; Breza, Martin; Lee, Wei -Tsung; ...

    2017-04-05

    High-oxidation state metal complexes with multiply bonded ligands are of great interest for both their reactivity as well as their fundamental bonding properties. This paper reports a combined spectroscopic and theoretical investigation into the effect of the apical multiply bonded ligand on the spin state preferences of three-fold symmetric iron(IV) complexes with tris(carbene) donor ligands. Specifically, singlet (S = 0) nitrido [{PhB(ImR)3}FeN], R = tBu (1), Mes (mesityl, 2) and the related triplet (S = 1) imido complexes, [{PhB(ImR)3}Fe(NR')]+, R = Mes, R' = Ad (1- adamantyl, 3), tBu (4), have been investigated by electronic absorption and Mössbauer effect spectroscopies.more » For comparison, two other Fe(IV) nitrido complexes, [(TIMENAr)FeN]+, (TIMENAr = tris[2-(3-aryl-imidazol-2-ylidene)ethyl]amine; Ar = Xyl (xylyl), Mes), have been investigated by 57Fe Mössbauer spectroscopy, including applied-field measurements. The paramagnetic imido complexes 3 and 4 were also studied by magnetic susceptibility measurements (for 3) and paramagnetic resonance spectroscopy: high-frequency and -field electron paramagnetic resonance (HFEPR) (for 3 and 4) and frequency-domain Fouriertransform (FD-FT) THz EPR (for 3), which reveal their zero-field splitting (zfs) parameters. Experimentally correlated theoretical studies comprising ligand-field theory (LFT) and quantum chemical theory (QCT), the latter including both density functional theory (DFT) and ab initio methods reveal the key role played by the Fe3dz2 (a1) orbital in these systems: the nature of its interaction with the nitrido or imido ligand dictates the spin state preference of the complex. Lastly, the ability to tune the spin state through the energy and nature of a single orbital has general relevance to the factors controlling spin states in complexes with applicability as single molecule devices.« less

  15. Spectroscopic and Computational Studies of Spin States of Iron(IV) Nitrido and Imido Complexes.

    PubMed

    Bucinsky, Lukas; Breza, Martin; Lee, Wei-Tsung; Hickey, Anne K; Dickie, Diane A; Nieto, Ismael; DeGayner, Jordan A; Harris, T David; Meyer, Karsten; Krzystek, J; Ozarowski, Andrew; Nehrkorn, Joscha; Schnegg, Alexander; Holldack, Karsten; Herber, Rolfe H; Telser, Joshua; Smith, Jeremy M

    2017-04-05

    High-oxidation-state metal complexes with multiply bonded ligands are of great interest for both their reactivity as well as their fundamental bonding properties. This paper reports a combined spectroscopic and theoretical investigation into the effect of the apical multiply bonded ligand on the spin-state preferences of threefold symmetric iron(IV) complexes with tris(carbene) donor ligands. Specifically, singlet (S = 0) nitrido [{PhB(Im(R))3}FeN], R = (t)Bu (1), Mes (mesityl, 2) and the related triplet (S = 1) imido complexes, [{PhB(Im(R))3}Fe(NR')](+), R = Mes, R' = 1-adamantyl (3), (t)Bu (4), were investigated by electronic absorption and Mössbauer effect spectroscopies. For comparison, two other Fe(IV) nitrido complexes, [(TIMEN(Ar))FeN](+) (TIMEN(Ar) = tris[2-(3-aryl-imidazol-2-ylidene)ethyl]amine; Ar = Xyl (xylyl), Mes), were investigated by (57)Fe Mössbauer spectroscopy, including applied-field measurements. The paramagnetic imido complexes 3 and 4 were also studied by magnetic susceptibility measurements (for 3) and paramagnetic resonance spectroscopy: high-frequency and -field electron paramagnetic resonance (for 3 and 4) and frequency-domain Fourier-transform (FD-FT) terahertz electron paramagnetic resonance (for 3), which reveal their zero-field splitting parameters. Experimentally correlated theoretical studies comprising ligand-field theory and quantum chemical theory, the latter including both density functional theory and ab initio methods, reveal the key role played by the Fe 3dz(2) (a1) orbital in these systems: the nature of its interaction with the nitrido or imido ligand dictates the spin-state preference of the complex. The ability to tune the spin state through the energy and nature of a single orbital has general relevance to the factors controlling spin states in complexes with applicability as single molecule devices.

  16. Non-spin-echo 3D transverse hadamard encoded proton spectroscopic imaging in the human brain.

    PubMed

    Cohen, Ouri; Tal, Assaf; Goelman, Gadi; Gonen, Oded

    2013-07-01

    A non-spin-echo multivoxel proton MR localization method based on three-dimensional transverse Hadamard spectroscopic imaging is introduced and demonstrated in a phantom and the human brain. Spatial encoding is achieved with three selective 90° radiofrequency pulses along perpendicular axes: The first two create a longitudinal ±M(Z) Hadamard order in the volume of interest. The third pulse spatially Hadamard-encodes the ±M(Z)s in the volume of interest in the third direction while bringing them to the transverse plane to be acquired immediately. The approaching-ideal point spread function of Hadamard encoding and very short acquisition delay yield signal-to-noise-ratios of 20 ± 8, 23 ± 9, and 31 ± 10 for choline, creatine, and N-acetylaspartate in the human brain at 1.5 T from 1 cm(3) voxels in 21 min. The advantages of transverse Hadamard spectroscopic imaging are that unlike gradient (Fourier) phase-encoding: (i) the volume of interest does not need to be smaller than the field of view to prevent aliasing; (ii) the number of partitions in each direction can be small, 8, 4, or even 2 at no cost in point spread function; (iii) the volume of interest does not have to be contiguous; and (iv) the voxel profile depends on the available B1 and pulse synthesis paradigm and can, therefore, at least theoretically, approach "ideal" "1" inside and "0" elsewhere.

  17. Modified spin-coating technique to achieve directional colloidal crystallization.

    PubMed

    Bartlett, Andrew P; Pichumani, Moorthi; Giuliani, Maximiliano; González-Viñas, Wenceslao; Yethiraj, Anand

    2012-02-14

    Fabricating large single crystals with colloidal spheres as building blocks is challenging and of competitive interest. Spin-coating of colloids offers a robust technique, which is highly reproducible in obtaining colloidal crystals even at fast dynamical regimes; however, these crystals are intrinsically polycrystalline due to the axial symmetry of spin-coating. We report a new method that applies a nonuniform electric field during the spin-coating process. By arranging the field direction to be stationary in the rotating frame, we are able to break the axial symmetry and to orient the colloids along one predefined direction. By regulating the applied field strength, we demonstrate local control over the orientation of the crystallites, and thus, the orientation is determined by the applied field strength.

  18. Optimal and suboptimal control technique for aircraft spin recovery

    NASA Technical Reports Server (NTRS)

    Young, J. W.

    1974-01-01

    An analytic investigation has been made of procedures for effecting recovery from equilibrium spin conditions for three assumed aircraft configurations. Three approaches which utilize conventional aerodynamic controls are investigated. Included are a constant control recovery mode, optimal recoveries, and a suboptimal control logic patterned after optimal recovery results. The optimal and suboptimal techniques are shown to yield a significant improvement in recovery performance over that attained by using a constant control recovery procedure.

  19. [Clinical applications of arterial spin labeling technique in brain diseases].

    PubMed

    Wang, Li; Zheng, Gang; Zhao, Tiezhu; Guo, Chao; Li, Lin; Lu, Guangming

    2013-02-01

    Arterial spin labeling (ASL) technique is a kind of perfusion functional magnetic resonance imaging method that is based on endogenous contrast, and it can measure cerebral blood flow (CBF) noninvasively. The ASL technique has advantages of noninvasiveness, simplicity and relatively lower costs so that it is more suitable for longitudinal studies compared with previous perfusion methods, such as positron emission tomography (PET), single photon emission computed tomography (SPECT), CT and the contrast agent based magnetic resonance perfusion imaging. This paper mainly discusses the current clinical applications of ASL in brain diseases as cerebrovascular diseases, brain tumors, Alzheimer's disease and epilepsy, etc.

  20. Configuration interaction studies on the spectroscopic properties of PbO including spin-orbit coupling

    NASA Astrophysics Data System (ADS)

    Wang, Luo; Rui, Li; Zhiqiang, Gai; RuiBo, Ai; Hongmin, Zhang; Xiaomei, Zhang; Bing, Yan

    2016-07-01

    Lead oxide (PbO), which plays the key roles in a range of research fields, has received a great deal of attention. Owing to the large density of electronic states and heavy atom Pb including in PbO, the excited states of the molecule have not been well studied. In this work, high level multireference configuration interaction calculations on the low-lying states of PbO have been carried out by utilizing the relativistic effective core potential. The effects of the core-valence correlation correction, the Davidson modification, and the spin-orbital coupling on the electronic structure of the PbO molecule are estimated. The potential energy curves of 18 Λ-S states correlated to the lowest dissociation limit (Pb (3Pg) + O(3Pg)) are reported. The calculated spectroscopic parameters of the electronic states below 30000 cm-1, for instance, X1Σ+, 13Σ+, and 13Σ-, and their spin-orbit coupling interaction, are compared with the experimental results, and good agreements are derived. The dipole moments of the 18 Λ-S states are computed with the configuration interaction method, and the calculated dipole moments of X1Σ+ and 13Σ+ are consistent with the previous experimental results. The transition dipole moments from 11Π, 21Π, and 21Σ+ to X1Σ+ and other singlet excited states are estimated. The radiative lifetime of several low-lying vibrational levels of 11Π, 21Π, and 21Σ+ states are evaluated. Project supported by the National Natural Science Foundation of China (Grant Nos. 11404180 and 11574114), the Natural Science Foundation of Heilongjiang Province, China (Grant No. A2015010), the University Nursing Program for Young Scholars with Creative Talents in Heilongjiang Province, China (Grant No. UNPYSCT-2015095), and the Natural Science Foundation of Jilin Province, China (Grant No. 20150101003JC).

  1. A spin-drying technique for lyopreservation of mammalian cells.

    PubMed

    Chakraborty, Nilay; Chang, Anthony; Elmoazzen, Heidi; Menze, Michael A; Hand, Steven C; Toner, Mehmet

    2011-05-01

    Stabilization of cellular material in the presence of glass-forming sugars at ambient temperatures is a viable approach that has many potential advantages over current cryogenic strategies. Experimental evidence indicates the possibility to preserve biomolecules in glassy matrices of low-molecular mobility using "glass-forming" sugars like trehalose at ambient temperatures. However, when cells are desiccated in trehalose solution using passive drying techniques, a glassy skin is formed at the liquid/vapor interface of the sample. This glassy skin prevents desiccation of the sample beyond a certain level of dryness and induces non-uniformities in the final water content. Cells trapped underneath this glassy skin may degrade due to a relatively high molecular mobility in the sample. This undesirable result underscores the need for development of a uniform, fast drying technique. In the present study, we report a new technique based on the principles of "spin drying" that can effectively address these problems. Forced convective evaporation of water along with the loss of solution due to centrifugal force leads to rapid vitrification of a thin layer of trehalose containing medium that remains on top of cells attached to the spinning glass substrate. The glassy layer produced has a consistent thickness and a small "surface-area-to-volume" ratio that minimizes any non-homogeneity. Thus, the chance of entrapping cells in a high-mobility environment decreases substantially. We compared numerical predictions to experimental observations of the drying time of 0.2-0.6 M trehalose solutions at a variety of spinning speeds ranging from 1000 to 4000 rpm. The model developed here predicts the formation of sugar films with thicknesses of 200-1000 nm, which was in good agreement with experimental results. Preliminary data suggest that after spin drying cells to about 0.159 ± 0.09 gH₂O/gdw (n = 11, ±SE), more than 95% of cells were able to preserve their membrane integrity

  2. Characterization of a laser-beam spinning technique

    SciTech Connect

    Brandon, E.

    1990-06-01

    The objective of this study was to evaluate the beam spinning technique for bridging gaps in butt joints that are CO{sub 2} laser-welded. A device was designed and built to circularly oscillate a CO{sub 2} laser beam on the plant of a work surface. A series of welds was made using a continuous-wave output power of 805 watts, and the resultant weld bead profile was characterized as a function of three process parameters. From the experimental results, predictor equations were derived for laser-beam spinning speed and amplitude of the beam spinning pattern on the work surface. The data collected in this experiment indicate that the width of the weld bead is increased by oscillating the beam and that this increase may be made without significantly reducing the weld penetration. The increased width of the weld may offer a solution to variable gaps in weld joints, which has been a recurring production problem. 13 figs., 1 tab.

  3. Investigation into Spectroscopic Techniques for Thermal Barrier Coating Spall Detection

    NASA Technical Reports Server (NTRS)

    deGroot, Wim; Opila, Beth

    2001-01-01

    Spectroscopic methods are proposed for detection of thermal barrier coating (TBC) spallation from engine hot zone components. These methods include absorption and emission of airborne marker species originally embedded in the TBC bond coat. In this study, candidate marker materials for this application were evaluated. Thermochemical analysis of candidate marker materials combined with additional constraints such as toxicity and uniqueness to engine environment, provided a short list of four potential species: platinum, copper oxide, zinc oxide. and indium. The melting point of indium was considered to be too low for serious consideration. The other three candidate marker materials, platinum, copper oxide, and zinc oxide were placed in a high temperature furnace and emission and absorption properties were measured over a temperature range from 800-1400 C and a spectral range from 250 to 18000 nm. Platinum did not provide the desired response, likely due to the low vapor Pressure of the metallic species and the low absorption of the oxide species. It was also found, however. that platinum caused a broadening of the carbon dioxide absorption at 4300 nm. The nature of this effect is not known. Absorption and emission caused by sodium and potassium impurities in the platinum were found in the platinum tests. Zinc oxide did not provide the desired response, again, most likely due to the low vapor pressure of the metallic species and the low absorption of the oxide species. Copper oxide generated two strongly temperature dependent absorption peaks at 324.8 and 327.4 nm. The melting point of copper oxide was determined to be too low for serious consideration as marker material.

  4. Understanding and controlling spin-systems using electron spin resonance techniques

    NASA Astrophysics Data System (ADS)

    Martens, Mathew

    the frequency of this nutation. Experimental findings fit well the analytical model developed. This process could lead to the use of multi-level spin systems as tunable solid state qubits. Finally, if quantum computing technologies are to be commercially realized, an on-chip method to address qubits must be developed. One way to incorporate SMMs to an on-chip device is by way of a coplanar waveguide (CPW) resonator. Efforts to create a resonator of this type to be used to perform low-temperature ESR on-chip will be described. Our work is focused on implementing such on-chip techniques in high magnetic fields, which is desirable for ESR-type of experiments in (quasi-)isotropic spin systems. Considerable attention is given to the coupling of these devices and a geometry is presented for a superconducting CPW resonator that is critically coupled. The effect of the magnetic field on the resonance position and its quality factor is addressed as well. Our devices show robust performance in field upwards of 1 Tesla and their use in performing on-chip ESR measurements seem promising.

  5. Characterization of Sorolla's gouache pigments by means of spectroscopic techniques

    NASA Astrophysics Data System (ADS)

    Roldán, Clodoaldo; Juanes, David; Ferrazza, Livio; Carballo, Jorgelina

    2016-02-01

    This paper presents the characterization of the Joaquín Sorolla's gouache sketches for the oil on canvas series "Vision of Spain" commissioned by A. M. Huntington to decorate the library of the Hispanic Society of America in New York. The analyses were focused on the identification of the elemental composition of the gouache pigments by means of portable EDXRF spectrometry in a non-destructive mode. Additionally, SEM-EDX and FTIR analyses of a selected set of micro-samples were carried out to identify completely the pigments, the paint technique and the binding media. The obtained results have confirmed the identification of lead and zinc white, vermillion, earth pigments, ochre, zinc yellow, chrome yellow, ultramarine, Prussian blue, chromium based and copper-arsenic based green pigments, bone black and carbon based black pigments, and the use of gum arabic as binding media in the gouache pigments.

  6. Fast magnetic resonance spectroscopic imaging techniques in human brain- applications in multiple sclerosis.

    PubMed

    Al-Iedani, Oun; Lechner-Scott, Jeannette; Ribbons, Karen; Ramadan, Saadallah

    2017-02-28

    Multi voxel magnetic resonance spectroscopic imaging (MRSI) is an important imaging tool that combines imaging and spectroscopic techniques. MRSI of the human brain has been beneficially applied to different clinical applications in neurology, particularly in neurooncology but also in multiple sclerosis, stroke and epilepsy. However, a major challenge in conventional MRSI is the longer acquisition time required for adequate signal to be collected. Fast MRSI of the brain in vivo is an alternative approach to reduce scanning time and make MRSI more clinically suitable.Fast MRSI can be categorised into spiral, echo-planar, parallel and turbo imaging techniques, each with its own strengths. After a brief introduction on the basics of non-invasive examination ((1)H-MRS) and localization techniques principles, different fast MRSI techniques will be discussed from their initial development to the recent innovations with particular emphasis on their capacity to record neurochemical changes in the brain in a variety of pathologies.The clinical applications of whole brain fast spectroscopic techniques, can assist in the assessment of neurochemical changes in the human brain and help in understanding the roles they play in disease. To give a good example of the utilities of these techniques in clinical context, MRSI application in multiple sclerosis was chosen. The available up to date and relevant literature is discussed and an outline of future research is presented.

  7. Breath Analysis Using Laser Spectroscopic Techniques: Breath Biomarkers, Spectral Fingerprints, and Detection Limits

    PubMed Central

    Wang, Chuji; Sahay, Peeyush

    2009-01-01

    Breath analysis, a promising new field of medicine and medical instrumentation, potentially offers noninvasive, real-time, and point-of-care (POC) disease diagnostics and metabolic status monitoring. Numerous breath biomarkers have been detected and quantified so far by using the GC-MS technique. Recent advances in laser spectroscopic techniques and laser sources have driven breath analysis to new heights, moving from laboratory research to commercial reality. Laser spectroscopic detection techniques not only have high-sensitivity and high-selectivity, as equivalently offered by the MS-based techniques, but also have the advantageous features of near real-time response, low instrument costs, and POC function. Of the approximately 35 established breath biomarkers, such as acetone, ammonia, carbon dioxide, ethane, methane, and nitric oxide, 14 species in exhaled human breath have been analyzed by high-sensitivity laser spectroscopic techniques, namely, tunable diode laser absorption spectroscopy (TDLAS), cavity ringdown spectroscopy (CRDS), integrated cavity output spectroscopy (ICOS), cavity enhanced absorption spectroscopy (CEAS), cavity leak-out spectroscopy (CALOS), photoacoustic spectroscopy (PAS), quartz-enhanced photoacoustic spectroscopy (QEPAS), and optical frequency comb cavity-enhanced absorption spectroscopy (OFC-CEAS). Spectral fingerprints of the measured biomarkers span from the UV to the mid-IR spectral regions and the detection limits achieved by the laser techniques range from parts per million to parts per billion levels. Sensors using the laser spectroscopic techniques for a few breath biomarkers, e.g., carbon dioxide, nitric oxide, etc. are commercially available. This review presents an update on the latest developments in laser-based breath analysis. PMID:22408503

  8. Mössbauer spectroscopic study on spin crossover coordination polymer Fe(3-Clpy)2[Pd(CN)4

    NASA Astrophysics Data System (ADS)

    Kitazawa, Takafumi; Sekiya, Madoka; Kawasaki, Takeshi; Takahashi, Masashi

    2016-12-01

    57Fe Mössbauer spectroscopic results on the alternatively prepared spin crossover coordination polymer Fe(3-Clpy)2Pd(CN)4 sample I agree with those of SQUID data. Mössbauer specrum at RT shows two diffrent doublets which correspond to the HS1(inner doublet) and HS2(outer doublet). The intensity of the HS1 doublet decreases on cooling to 78 K at the expense of a new one featuring the LS singlet. Almost 100 % of HS1 change to LS singlet due to iron(II) ions coordinated by four N atoms of cyano groups and two N atoms of 3-Clpy ligand in the sample I. The SQUID data of the sample I prepared by a new direct contact method are different from those of the already reported Fe(3-Clpy)2Pd(CN)4 sample. The differences of the SQUID data are associated with particle size effects in molecule spin crossover samples.

  9. Non-Destructive and rapid evaluation of staple foods quality by using spectroscopic techniques: A review.

    PubMed

    Su, Wen-Hao; He, Hong-Ju; Sun, Da-Wen

    2017-03-24

    Staple foods, including cereals, legumes, and root/tuber crops, dominate the daily diet of humans by providing valuable proteins, starch, oils, minerals, and vitamins. Quality evaluation of staple foods is primarily carried out on sensory (e.g. external defect, color), adulteration (e.g. species, origin), chemical (e.g. starch, proteins), mycotoxin (e.g. Fusarium toxin, aflatoxin), parasitic infection (e.g. weevil, beetle), and internal physiological (e.g. hollow heart, black heart) aspects. Conventional methods for the quality assessment of staple foods are always laborious, destructive, and time-consuming. Requirements for online monitoring of staple foods have been proposed to encourage the development of rapid, reagentless, and noninvasive techniques. Spectroscopic techniques, such as visible-infrared spectroscopy, Raman spectroscopy, nuclear magnetic resonance spectroscopy, and spectral imaging, have been introduced as promising analytical tools and applied for the quality evaluation of staple foods. This review summarizes the recent applications and progress of such spectroscopic techniques in determining various qualities of staple foods. Besides, challenges and future trends of these spectroscopic techniques are also presented.

  10. Advanced in situ spectroscopic techniques and their applications in environmental biogeochemistry: introduction to the special section.

    PubMed

    Lombi, Enzo; Hettiarachchi, Ganga M; Scheckel, Kirk G

    2011-01-01

    Understanding the molecular-scale complexities and interplay of chemical and biological processes of contaminants at solid, liquid, and gas interfaces is a fundamental and crucial element to enhance our understanding of anthropogenic environmental impacts. The ability to describe the complexity of environmental biogeochemical reaction mechanisms relies on our analytical ability through the application and developmemnt of advanced spectroscopic techniques. Accompanying this introductory article are nine papers that either review advanced in situ spectroscopic methods or present original research utilizing these techniques. This collection of articles summarizes the challenges facing environmental biogeochemistry, highlights the recent advances and scientific gaps, and provides an outlook into future research that may benefit from the use of in situ spectroscopic approaches. The use of synchrotron-based techniques and other methods are discussed in detail, as is the importance to integrate multiple analytical approaches to confirm results of complementary procedures or to fill data gaps. We also argue that future direction in research will be driven, in addition to recent analytical developments, by emerging factors such as the need for risk assessment of new materials (i.e., nanotechnologies) and the realization that biogeochemical processes need to be investigated in situ under environmentally relevant conditions.

  11. Application of spectroscopic techniques for the study of paper documents: A survey

    NASA Astrophysics Data System (ADS)

    Manso, M.; Carvalho, M. L.

    2009-06-01

    For many centuries paper was the main material for recording cultural achievements all over the world. Paper is mostly made from cellulose with small amounts of organic and inorganic additives, which allow its identification and characterization and may also contribute to its degradation. Prior to 1850, paper was made entirely from rags, using hemp, flax and cotton fibres. After this period, due to the enormous increase in demand, wood pulp began to be commonly used as raw material, resulting in rapid degradation of paper. Spectroscopic techniques represent one of the most powerful tools to investigate the constituents of paper documents in order to establish its identification and its state of degradation. This review describes the application of selected spectroscopic techniques used for paper characterization and conservation. The spectroscopic techniques that have been used and will be reviewed include: Fourier-Transform Infrared spectroscopy, Raman spectroscopy, Nuclear Magnetic Resonance spectroscopy, X-Ray spectroscopy, Laser-based Spectroscopy, Inductively Coupled Mass Spectroscopy, Laser ablation, Atomic Absorption Spectroscopy and X-Ray Photoelectron Spectroscopy.

  12. Mean field spin glasses treated with PDE techniques

    NASA Astrophysics Data System (ADS)

    Barra, Adriano; Del Ferraro, Gino; Tantari, Daniele

    2013-07-01

    Following an original idea of Guerra, in these notes we analyze the Sherrington-Kirkpatrick model from different perspectives, all sharing the underlying approach which consists in linking the resolution of the statistical mechanics of the model (e.g. solving for the free energy) to well-known partial differential equation (PDE) problems (in suitable spaces). The plan is then to solve the related PDE using techniques involved in their native field and lastly bringing back the solution in the proper statistical mechanics framework. Within this strand, after a streamlined test-case on the Curie-Weiss model to highlight the methods more than the physics behind, we solve the SK both at the replica symmetric and at the 1-RSB level, obtaining the correct expression for the free energy via an analogy to a Fourier equation and for the self-consistencies with an analogy to a Burger equation, whose shock wave develops exactly at critical noise level (triggering the phase transition). Our approach, beyond acting as a new alternative method (with respect to the standard routes) for tackling the complexity of spin glasses, links symmetries in PDE theory with constraints in statistical mechanics and, as a novel result from the theoretical physics perspective, we obtain a new class of polynomial identities (namely of Aizenman-Contucci type, but merged within the Guerra's broken replica measures), whose interest lies in understanding, via the recent Panchenko breakthroughs, how to force the overlap organization to the ultrametric tree predicted by Parisi.

  13. Field dependence of the spin state and spectroscopic modes of multiferroic BiFeO3

    NASA Astrophysics Data System (ADS)

    Fishman, Randy S.

    2013-06-01

    The spectroscopic modes of multiferroic BiFeO3 provide detailed information about the very small anisotropy and Dzyaloshinskii-Moriya (DM) interactions responsible for the long-wavelength, distorted cycloid below TN=640 K. A microscopic model that includes two DM interactions and easy-axis anisotropy predicts both the zero-field spectroscopic modes as well as their splitting and evolution in a magnetic field applied along a cubic axis. While only six modes are optically active in zero field, all modes at the cycloidal wave vector are activated by a magnetic field. The three magnetic domains of the cycloid are degenerate in zero field but one domain has lower energy than the other two in nonzero field. Measurements imply that the higher-energy domains are depopulated above about 6 T and have a maximum critical field of 16 T, below the critical field of 19 T for the lowest-energy domain. Despite the excellent agreement with the measured spectroscopic frequencies, some discrepancies with the measured spectroscopic intensities suggest that other weak interactions may be missing from the model.

  14. The role of simulation chambers in the development of spectroscopic techniques: campaigns at EUPHORE

    NASA Astrophysics Data System (ADS)

    Ródenas, Milagros; Muñoz, Amalia; Euphore Team

    2016-04-01

    Simulation chambers represent a very useful tool for the study of chemical reactions and their products, but also to characterize instruments. The development of spectroscopic techniques throughout the last decades has benefited from tests and intercomparison exercises carried out in chambers. In fact, instruments can be exposed to various controlled atmospheric scenarios that account for different environmental conditions, eliminating the uncertainties associated to fluctuations of the air mass, which must be taken into account when extrapolating results to the real conditions. Hence, a given instrument can be characterized by assessing its precision, accuracy, detection limits, time response and potential interferences in the presence of other chemical compounds, aerosols, etc. This implies that the instrument can be calibrated and validated, which allows to enhance the features of the instrument. Moreover, chambers are also the scenario of intercomparison trials, permitting multiple instruments to sample from the same well-mixed air mass simultaneously. An overview of different campaigns to characterize and/or intercompare spectroscopic techniques that have taken place in simulation chambers will be given; in particular, those carried out at EUPHORE (two twin domes, 200 m3 each, Spain), where various intercomparison exercises have been deployed under the frame of European projects (e.g. TOXIC, FIONA, PSOA campaigns supported by EUROCHAMP-II). With the common aim of measuring given compounds (e.g. HONO, NO2, OH, glyoxal, m-glyoxal, etc), an important number of spectroscopic instruments and institutions have been involved in chamber experiments, having the chance to intercompare among them and also with other non-spectroscopic systems (e.g. monitors, cromatographs, etc) or model simulations.

  15. One- and two-dimensional infrared spectroscopic studies of solution-phase homogeneous catalysis and spin-forbidden reactions

    SciTech Connect

    Sawyer, Karma Rae

    2008-12-01

    Understanding chemical reactions requires the knowledge of the elementary steps of breaking and making bonds, and often a variety of experimental techniques are needed to achieve this goal. The initial steps occur on the femto- through picosecond time-scales, requiring the use of ultrafast spectroscopic methods, while the rate-limiting steps often occur more slowly, requiring alternative techniques. Ultrafast one and two-dimensional infrared and step-scan FTIR spectroscopies are used to investigate the photochemical reactions of four organometallic complexes. The analysis leads to a detailed understanding of mechanisms that are general in nature and may be applicable to a variety of reactions.

  16. Meniscal tears: comparison of the conventional spin-echo and fast spin-echo techniques through image processing

    PubMed Central

    2014-01-01

    Background Conventional spin-echo (PD-CSE) and fast spin-echo (PD-FSE) techniques are frequently used to detect meniscal tears. However, the time delay for imaging with PD-CSE has resulted in its replacement with faster techniques, such as proton density fast spin-echo (PD-FSE), which has become a frequent tool at most diagnostic centres. Qualitative analysis shows that the PD-CSE technique is more sensitive, but other authors have not found significant differences between the aforementioned techniques. Therefore, we performed a quantitative analysis in this study that aims to measure differences in the quality of the images obtained with both techniques. Methods We compared the PD-CSE and PD-FSE techniques by quantitatively analysing the obtained proton density images: the area shown, as well as the brightness and lesion contrast of the obtained image. A set of 100 images from 50 patients thought to contain meniscal tears of the knee were selected. These 100 images were obtained from all individuals using both the PD-CSE and PD-FSE techniques. The images were processed using software developed in Delphi. In addition to these quantifications, three physicians, who are specialists in radiology and capable of analysing magnetic resonance (MR) images of the musculoskeletal system, qualitatively analysed the diagnostic sensitivity of both techniques. Results On average, samples obtained via the PD-CSE technique contained 22% more pixels in the lesion area. The contrast differed by 28%, and the brightness differed by 31%. The two techniques were correlated using Student’s t-test, which showed a statistically significant difference. The specialists detected meniscal tears in 30 of the images obtained via the PD-CSE technique, while only 72% of these cases were detected via the PD-FSE technique. Conclusions The PD-CSE technique was shown to be superior to PD-FSE for all of the evaluated properties, making its selection preferable. PMID:24673813

  17. Methodological considerations of electron spin resonance spin trapping techniques for measuring reactive oxygen species generated from metal oxide nanomaterials

    NASA Astrophysics Data System (ADS)

    Jeong, Min Sook; Yu, Kyeong-Nam; Chung, Hyun Hoon; Park, Soo Jin; Lee, Ah Young; Song, Mi Ryoung; Cho, Myung-Haing; Kim, Jun Sung

    2016-05-01

    Qualitative and quantitative analyses of reactive oxygen species (ROS) generated on the surfaces of nanomaterials are important for understanding their toxicity and toxic mechanisms, which are in turn beneficial for manufacturing more biocompatible nanomaterials in many industrial fields. Electron spin resonance (ESR) is a useful tool for detecting ROS formation. However, using this technique without first considering the physicochemical properties of nanomaterials and proper conditions of the spin trapping agent (such as incubation time) may lead to misinterpretation of the resulting data. In this report, we suggest methodological considerations for ESR as pertains to magnetism, sample preparation and proper incubation time with spin trapping agents. Based on our results, each spin trapping agent should be given the proper incubation time. For nanomaterials having magnetic properties, it is useful to remove these nanomaterials via centrifugation after reacting with spin trapping agents. Sonication for the purpose of sample dispersion and sample light exposure should be controlled during ESR in order to enhance the obtained ROS signal. This report will allow researchers to better design ESR spin trapping applications involving nanomaterials.

  18. Effects of spin diffusion on electron spin relaxation time measured with a time-resolved microscopic photoluminescence technique

    SciTech Connect

    Ikeda, Kazuhiro Kawaguchi, Hitoshi

    2015-02-07

    We performed measurements at room temperature for a GaAs/AlGaAs multiple quantum well grown on GaAs(110) using a time-resolved microscopic photoluminescence (micro-PL) technique to find what effects spin diffusion had on the measured electron spin relaxation time, τ{sub s}, and developed a method of estimating the spin diffusion coefficient, D{sub s}, using the measured data and the coupled drift-diffusion equations for spin polarized electrons. The spatial nonuniformities of τ{sub s} and the initial degree of electron spin polarization caused by the pump intensity distribution inside the focal spot were taken into account to explain the dependence of τ{sub s} on the measured spot size, i.e., a longer τ{sub s} for a smaller spot size. We estimated D{sub s} as ∼100 cm{sup 2}/s, which is similar to a value reported in the literature. We also provided a qualitative understanding on how spin diffusion lengthens τ{sub s} in micro-PL measurements.

  19. A COMPARISON OF SPECTROSCOPIC VERSUS IMAGING TECHNIQUES FOR DETECTING CLOSE COMPANIONS TO KEPLER OBJECTS OF INTEREST

    SciTech Connect

    Teske, Johanna K.; Everett, Mark E.; Hirsch, Lea; Furlan, Elise; Ciardi, David R.; Horch, Elliott P.; Howell, Steve B.; Gonzales, Erica; Crepp, Justin R.

    2015-11-15

    Kepler planet candidates require both spectroscopic and imaging follow-up observations to rule out false positives and detect blended stars. Traditionally, spectroscopy and high-resolution imaging have probed different host star companion parameter spaces, the former detecting tight binaries and the latter detecting wider bound companions as well as chance background stars. In this paper, we examine a sample of 11 Kepler host stars with companions detected by two techniques—near-infrared adaptive optics and/or optical speckle interferometry imaging, and a new spectroscopic deblending method. We compare the companion effective temperatures (T{sub eff}) and flux ratios (F{sub B}/F{sub A}, where A is the primary and B is the companion) derived from each technique and find no cases where both companion parameters agree within 1σ errors. In 3/11 cases the companion T{sub eff} values agree within 1σ errors, and in 2/11 cases the companion F{sub B}/F{sub A} values agree within 1σ errors. Examining each Kepler system individually considering multiple avenues (isochrone mapping, contrast curves, probability of being bound), we suggest two cases for which the techniques most likely agree in their companion detections (detect the same companion star). Overall, our results support the advantage that the spectroscopic deblending technique has for finding very close-in companions (θ ≲ 0.″02–0.″05) that are not easily detectable with imaging. However, we also specifically show how high-contrast AO and speckle imaging observations detect companions at larger separations (θ ≥ 0.″02–0.″05) that are missed by the spectroscopic technique, provide additional information for characterizing the companion and its potential contamination (e.g., position angle, separation, magnitude differences), and cover a wider range of primary star effective temperatures. The investigation presented here illustrates the utility of combining the two techniques to reveal higher

  20. Quantification of UV-Visible and Laser Spectroscopic Techniques for Materials Accountability and Process Control

    SciTech Connect

    Czerwinski, Kenneth; Weck, Phil

    2013-09-13

    Ultraviolet–visible spectroscopy (UV–Visible) and time-resolved laser fluorescence spectroscopy (TRLFS) optical techniques can permit on-line analysis of actinide elements in a solvent extraction process in real time. These techniques have been used for measuring actinide speciation and concentration under laboratory conditions and are easily adaptable to multiple sampling geometries, such as dip probes, fiber-optic sample cells, and flow-through cell geometries. To fully exploit these techniques, researchers must determine the fundamental speciation of target actinides and the resulting influence on spectroscopic properties. Detection limits, process conditions, and speciation of key actinide components can be established and utilized in a range of areas, particularly those related to materials accountability and process control. Through this project, researchers will develop tools and spectroscopic techniques to evaluate solution extraction conditions and concentrations of U, Pu, and Cm in extraction processes, addressing areas of process control and materials accountability. The team will evaluate UV– Visible and TRLFS for use in solvent extraction-based separations. Ongoing research is examining efficacy of UV-Visible spectroscopy to evaluate uranium and plutonium speciation under conditions found in the UREX process and using TRLFS to evaluate Cm speciation and concentration in the TALSPEAK process. A uranyl and plutonium nitrate UV–Visible spectroscopy study met with success, which supports the utility and continued exploration of spectroscopic methods for evaluation of actinide concentrations and solution conditions for other aspects of the UREX+ solvent extraction scheme. This project will examine U and Pu absorbance in TRUEX and TALSPEAK, perform detailed examination of Cm in TRUEX and TALSPEAK, study U laser fluorescence, and apply project data to contactors. The team will also determine peak ratios as a function of solution concentrations for the

  1. Vibrational Spectroscopic Microscopy: Raman, Near-Infrared and Mid-Infrared Imaging Techniques

    NASA Astrophysics Data System (ADS)

    Lewis, E. Neil; Levin, Ira W.

    1995-02-01

    New instrumental approaches for performing vibrational Raman, near-infrared and mid-infrared spectroscopic imaging microscopy are described. The instruments integrate imaging quality filters such as acousto-optic tunable filters (AOTFs), with visible charge-coupled device (CCD) and infrared focal-plane array detectors. These systems are used in conjunction with infinity-corrected, refractive microscopes for operation in the visible and near-infrared spectral regions and with Cassegrainian reflective optics for operation in the mid-infrared spectral interval. Chemically specific images at moderate spectral resolution (2 nm) and high spatial resolution (1 [mu]m) can be collected rapidly and noninvasively. Image data are presented containing 128 × 128 pixels, although significantly larger format images can be collected in approximately the same time. The instruments can be readily configured for both absorption and reflectance spectroscopies. We present Raman emission images of polystyrene microspheres and a lipid/amino acid mixture and near-infrared images of onion epidermis and a hydrated phospholipid dispersion. Images generated from mid-infrared spectral data are presented for a KBr disk containing nonhomogeneous domains of lipid and for 50-[mu]m slices of monkey cerebellum. These are the first results illustrating the use of infrared focal-plane array detectors as chemically specific spectroscopic imaging devices and demonstrating their application in biomolecular areas. Extensions and future applications of the various vibrational spectroscopic imaging techniques are discussed.

  2. How to Calculate Spin-Spin Coupling and Spin-Rotation Coupling Strengths and Their Uncertainties from Spectroscopic Data: Application to the c(1^3Σ_g^+) State of Diatomic Lithium

    NASA Astrophysics Data System (ADS)

    Dattani, Nikesh S.; Li, Xuan

    2013-06-01

    Recent high-resolution (± 0.00002 cm^{-1}) photo-association spectroscopy (PAS) data of seven previously unexplored vibrational levels of the 1^3Σ_g^+ state of Li_2 have allowed for the first ever experimental determination of the spin-spin (λ_v) and spin-rotation (γ_v) coupling constants in a diatomic lithium system. For triplet states of diatomic molecules such as the 1^3Σ_g^+ state of Li_2, the three spin-spin/spin-rotation resolved energies associated with a ro-vibrational state |v,N> were expressed explicity in terms of B_v, λ_v, and γ_v in 1929 by Kramer's first-order formulas and then in 1937 by Schlapp's more refined formulas. Given spectroscopic data, while it has never been difficult to extract λ_v and γ_v from Schlapp's formulas, it has been a challenge to reliably predict how accurate these extracted values are. This is for two reasons: (1) the lack of a rigorous method to estimate the uncertainty in B_v, (2) the non-linearity of Schlapp's coupled equations has meant that traditionally they have had to be solved numerically by Newton iterations which makes error propagation difficult. The former challenge has been this year solved by Le Roy with a modification of Hutson's perturbation theory of, and the latter problem has now been solved by symbolic computing software that solves Schlapp's coupled non-linear equations analytically for the first time since their introduction in 1937. M. Semczuk, X. Li, W. Gunton, M. Haw, N. Dattani, J. Witz, A. Mills, D. Jones, K. Madison, Physical Review A {87}, XX (2013) H. Kramers, Zeitschrift fur Physik {53}, 422 (1929) R. Schlapp, Physical Review {51}, 342 (1937) J. Hutson, J. Phys. B, {14}, 851 (1981)

  3. Interferometrically stable, enclosed, spinning sample cell for spectroscopic experiments on air-sensitive samples

    NASA Astrophysics Data System (ADS)

    Baranov, Dmitry; Hill, Robert J.; Ryu, Jisu; Park, Samuel D.; Huerta-Viga, Adriana; Carollo, Alexa R.; Jonas, David M.

    2017-01-01

    In experiments with high photon flux, it is necessary to rapidly remove the sample from the beam and to delay re-excitation until the sample has returned to equilibrium. Rapid and complete sample exchange has been a challenge for air-sensitive samples and for vibration-sensitive experiments. Here, a compact spinning sample cell for air and moisture sensitive liquid and thin film samples is described. The principal parts of the cell are a copper gasket sealed enclosure, a 2.5 in. hard disk drive motor, and a reusable, chemically inert glass sandwich cell. The enclosure provides an oxygen and water free environment at the 1 ppm level, as demonstrated by multi-day tests with sodium benzophenone ketyl radical. Inside the enclosure, the glass sandwich cell spins at ≈70 Hz to generate tangential speeds of 7-12 m/s that enable complete sample exchange at 100 kHz repetition rates. The spinning cell is acoustically silent and compatible with a ±1 nm rms displacement stability interferometer. In order to enable the use of the spinning cell, we discuss centrifugation and how to prevent it, introduce the cycle-averaged resampling rate to characterize repetitive excitation, and develop a figure of merit for a long-lived photoproduct buildup.

  4. Interferometrically stable, enclosed, spinning sample cell for spectroscopic experiments on air-sensitive samples.

    PubMed

    Baranov, Dmitry; Hill, Robert J; Ryu, Jisu; Park, Samuel D; Huerta-Viga, Adriana; Carollo, Alexa R; Jonas, David M

    2017-01-01

    In experiments with high photon flux, it is necessary to rapidly remove the sample from the beam and to delay re-excitation until the sample has returned to equilibrium. Rapid and complete sample exchange has been a challenge for air-sensitive samples and for vibration-sensitive experiments. Here, a compact spinning sample cell for air and moisture sensitive liquid and thin film samples is described. The principal parts of the cell are a copper gasket sealed enclosure, a 2.5 in. hard disk drive motor, and a reusable, chemically inert glass sandwich cell. The enclosure provides an oxygen and water free environment at the 1 ppm level, as demonstrated by multi-day tests with sodium benzophenone ketyl radical. Inside the enclosure, the glass sandwich cell spins at ≈70 Hz to generate tangential speeds of 7-12 m/s that enable complete sample exchange at 100 kHz repetition rates. The spinning cell is acoustically silent and compatible with a ±1 nm rms displacement stability interferometer. In order to enable the use of the spinning cell, we discuss centrifugation and how to prevent it, introduce the cycle-averaged resampling rate to characterize repetitive excitation, and develop a figure of merit for a long-lived photoproduct buildup.

  5. A versatile setup using femtosecond adaptive spectroscopic techniques for coherent anti-Stokes Raman scattering

    SciTech Connect

    Shen, Yujie; Voronine, Dmitri V.; Sokolov, Alexei V.; Scully, Marlan O.

    2015-08-15

    We report a versatile setup based on the femtosecond adaptive spectroscopic techniques for coherent anti-Stokes Raman scattering. The setup uses a femtosecond Ti:Sapphire oscillator source and a folded 4f pulse shaper, in which the pulse shaping is carried out through conventional optical elements and does not require a spatial light modulator. Our setup is simple in alignment, and can be easily switched between the collinear single-beam and the noncollinear two-beam configurations. We demonstrate the capability for investigating both transparent and highly scattering samples by detecting transmitted and reflected signals, respectively.

  6. A versatile setup using femtosecond adaptive spectroscopic techniques for coherent anti-Stokes Raman scattering.

    PubMed

    Shen, Yujie; Voronine, Dmitri V; Sokolov, Alexei V; Scully, Marlan O

    2015-08-01

    We report a versatile setup based on the femtosecond adaptive spectroscopic techniques for coherent anti-Stokes Raman scattering. The setup uses a femtosecond Ti:Sapphire oscillator source and a folded 4f pulse shaper, in which the pulse shaping is carried out through conventional optical elements and does not require a spatial light modulator. Our setup is simple in alignment, and can be easily switched between the collinear single-beam and the noncollinear two-beam configurations. We demonstrate the capability for investigating both transparent and highly scattering samples by detecting transmitted and reflected signals, respectively.

  7. FAST CARS: engineering a laser spectroscopic technique for rapid identification of bacterial spores.

    PubMed

    Scully, M O; Kattawar, G W; Lucht, R P; Opatrny, T; Pilloff, H; Rebane, A; Sokolov, A V; Zubairy, M S

    2002-08-20

    Airborne contaminants, e.g., bacterial spores, are usually analyzed by time-consuming microscopic, chemical, and biological assays. Current research into real-time laser spectroscopic detectors of such contaminants is based on e.g., resonance fluorescence. The present approach derives from recent experiments in which atoms and molecules are prepared by one (or more) coherent laser(s) and probed by another set of lasers. However, generating and using maximally coherent oscillation in macromolecules having an enormous number of degrees of freedom is challenging. In particular, the short dephasing times and rapid internal conversion rates are major obstacles. However, adiabatic fast passage techniques and the ability to generate combs of phase-coherent femtosecond pulses provide tools for the generation and utilization of maximal quantum coherence in large molecules and biopolymers. We call this technique FAST CARS (femtosecond adaptive spectroscopic techniques for coherent anti-Stokes Raman spectroscopy), and the present article proposes and analyses ways in which it could be used to rapidly identify preselected molecules in real time.

  8. FAST CARS: Engineering a laser spectroscopic technique for rapid identification of bacterial spores

    PubMed Central

    Scully, M. O.; Kattawar, G. W.; Lucht, R. P.; Opatrný, T.; Pilloff, H.; Rebane, A.; Sokolov, A. V.; Zubairy, M. S.

    2002-01-01

    Airborne contaminants, e.g., bacterial spores, are usually analyzed by time-consuming microscopic, chemical, and biological assays. Current research into real-time laser spectroscopic detectors of such contaminants is based on e.g., resonance fluorescence. The present approach derives from recent experiments in which atoms and molecules are prepared by one (or more) coherent laser(s) and probed by another set of lasers. However, generating and using maximally coherent oscillation in macromolecules having an enormous number of degrees of freedom is challenging. In particular, the short dephasing times and rapid internal conversion rates are major obstacles. However, adiabatic fast passage techniques and the ability to generate combs of phase-coherent femtosecond pulses provide tools for the generation and utilization of maximal quantum coherence in large molecules and biopolymers. We call this technique FAST CARS (femtosecond adaptive spectroscopic techniques for coherent anti-Stokes Raman spectroscopy), and the present article proposes and analyses ways in which it could be used to rapidly identify preselected molecules in real time. PMID:12177405

  9. Explaining the Cyclic Voltammetry of a Poly(1,4-phenylene-ethynylene)-alt-poly(1,4-phenylene-vinylene) Copolymer upon Oxidation by using Spectroscopic Techniques.

    PubMed

    Enengl, Christina; Enengl, Sandra; Bouguerra, Nassima; Havlicek, Marek; Neugebauer, Helmut; Egbe, Daniel A M

    2017-01-04

    Poly(1,4-phenylene-ethynylene)-alt-poly(1,4-phenylene-vinylene) (PPE-PPV) copolymers have attracted quite a lot of attention in the last few years for electronic device applications owing to their enhanced fluorescence. In this work, we focus on one particular PPE-PPV copolymer with dissymmetrically substituted 1,4-phenylene-ethynylene and symmetrically substituted 1,4-phenylene-vinylene building units. Six successively performed cyclic voltammograms are presented, measured during the oxidation reactions. As the oxidation onset of the electrochemical reaction shifts to lower potentials in each cycle, this behavior is elucidated by using spectroscopic techniques ranging from UV/Vis/near-IR to mid-IR including spin-resonance techniques. Hence, these findings help to explain some of the copolymer's most advantageous properties in terms of possible oxidation products.

  10. Spin state and spectroscopic modes of multiferroic BiFeO3

    NASA Astrophysics Data System (ADS)

    Fishman, Randy S.; Haraldsen, Jason T.; Furukawa, Nobuo; Miyahara, Shin

    2013-04-01

    Spectroscopic modes provide the most sensitive probe of the very weak interactions responsible for the properties of the long-wavelength cycloid in the multiferroic phase of BiFeO3 below TN≈640 K. Three of the four modes measured by terahertz (THz) and Raman spectroscopies were recently identified using a simple microscopic model. While a Dzyaloshinskii-Moriya (DM) interaction D along [-1,2,-1] induces a cycloid with wave vector (2π/a)(0.5+δ,0.5,0.5-δ) (δ≈0.0045), easy-axis anisotropy K along the [1,1,1] direction of the electric polarization P induces higher harmonics of the cycloid, which split the Ψ1 modes at 2.49 and 2.67 meV and activate the Φ2 mode at 3.38 meV. However, that model could not explain the observed low-frequency mode at about 2.17 meV. We now demonstrate that an additional DM interaction D' along [1,1,1] not only produces the observed weak ferromagnetic moment of the high-field phase above 18 T but also activates the spectroscopic matrix elements of the nearly degenerate, low-frequency Ψ0 and Φ1 modes, although their scattering intensities remain extremely weak. Even in the absence of easy-axis anisotropy, D' produces cycloidal harmonics that split Ψ1 and activate Φ2. However, the observed mode frequencies and selection rules require that both D' and K are nonzero. This work also resolves an earlier disagreement between spectroscopic and inelastic neutron-scattering measurements.

  11. Spectroscopic investigation on cocrystal formation between adenine and fumaric acid based on infrared and Raman techniques.

    PubMed

    Du, Yong; Fang, Hong Xia; Zhang, Qi; Zhang, Hui Li; Hong, Zhi

    2016-01-15

    As an important component of double-stranded DNA, adenine has powerful hydrogen-bond capability, due to rich hydrogen bond donors and acceptors existing within its molecular structure. Therefore, it is easy to form cocrystal between adenine and other small molecules with intermolecular hydrogen-bond effect. In this work, cocrystal of adenine and fumaric acid has been characterized as model system by FT-IR and FT-Raman spectral techniques. The experimental results show that the cocrystal formed between adenine and fumaric acid possesses unique spectroscopical characteristic compared with that of starting materials. Density functional theory (DFT) calculation has been performed to optimize the molecular structures and simulate vibrational modes of adenine, fumaric acid and the corresponding cocrystal. Combining the theoretical and experimental vibrational results, the characteristic bands corresponding to bending and stretching vibrations of amino and carbonyl groups within cocrystal are shifted into lower frequencies upon cocrystal formation, and the corresponding bond lengths show some increase due to the effect of intermolecular hydrogen bonding. Different vibrational modes shown in the experimental spectra have been assigned based on the simulation DFT results. The study could provide experimental and theoretical benchmarks to characterize cocrystal formed between active ingredients and cocrystal formers and also the intermolecular hydrogen-bond effect within cocrystal formation process by vibrational spectroscopic techniques.

  12. Spectroscopic investigation on cocrystal formation between adenine and fumaric acid based on infrared and Raman techniques

    NASA Astrophysics Data System (ADS)

    Du, Yong; Fang, Hong Xia; Zhang, Qi; Zhang, Hui Li; Hong, Zhi

    2016-01-01

    As an important component of double-stranded DNA, adenine has powerful hydrogen-bond capability, due to rich hydrogen bond donors and acceptors existing within its molecular structure. Therefore, it is easy to form cocrystal between adenine and other small molecules with intermolecular hydrogen-bond effect. In this work, cocrystal of adenine and fumaric acid has been characterized as model system by FT-IR and FT-Raman spectral techniques. The experimental results show that the cocrystal formed between adenine and fumaric acid possesses unique spectroscopical characteristic compared with that of starting materials. Density functional theory (DFT) calculation has been performed to optimize the molecular structures and simulate vibrational modes of adenine, fumaric acid and the corresponding cocrystal. Combining the theoretical and experimental vibrational results, the characteristic bands corresponding to bending and stretching vibrations of amino and carbonyl groups within cocrystal are shifted into lower frequencies upon cocrystal formation, and the corresponding bond lengths show some increase due to the effect of intermolecular hydrogen bonding. Different vibrational modes shown in the experimental spectra have been assigned based on the simulation DFT results. The study could provide experimental and theoretical benchmarks to characterize cocrystal formed between active ingredients and cocrystal formers and also the intermolecular hydrogen-bond effect within cocrystal formation process by vibrational spectroscopic techniques.

  13. Studies on Nephrite and Jadeite Jades by Fourier Transform Infrared (ftir) and Raman Spectroscopic Techniques

    NASA Astrophysics Data System (ADS)

    Tan, T. L.; Ng, L. L.; Lim, L. C.

    2013-10-01

    The mineralogical properties of black nephrite jade from Western Australia are studied by Fourier transform infrared (FTIR) spectroscopy using both transmission and specular reflectance techniques in the 4000-400 cm-1 wavenumber region. The infrared absorption peaks in the 3700-3600 cm-1 region which are due to the O-H stretching mode provides a quantitative analysis of the Fe/(Fe+Mg) ratio in the mineral composition of jade samples. The Fe/(Fe+Mg) percentage in black nephrite is found to be higher than that in green nephrite, but comparable to that of actinolite (iron-rich nephrite). This implies that the mineralogy of black nephrite is closer to actinolite than tremolite. The jade is also characterized using Raman spectroscopy in the 1200-200 cm-1 region. Results from FTIR and Raman spectroscopic data of black nephrite jade are compared with those of green nephrite jade from New Zealand and jadeite jade from Myanmar. Black nephrite appears to have a slightly different chemical composition from green nephrite. Spectra from FTIR and Raman spectroscopic techniques were found to be useful in differentiating black nephrite, green nephrite, and green jadeite jades. Furthermore, data on refractive index, specific gravity, and hardness of black nephrite jade are measured and compared with those of green nephrite and of jadeite jade.

  14. Implementation of Multiple Spectroscopic Techniques to Simultaneously Observe Native and Mutated Protein Unfolding

    NASA Astrophysics Data System (ADS)

    Cull, Brennan; Ben, Kelty; Link, Justin

    A protein's natural, correctly folded structure can determine the protein's ability to carry out its function. If the unfolding process of proteins can be observed, then the relative stability can be better understood between native and mutated proteins. A global picture of the unfolding process may be completed through the studies of strategically mutated proteins using tryptophan as a probe. Horse heart cytochrome c, a thoroughly studied, model protein was used in our investigation to explore this idea. Various spectroscopic techniques such as circular dichroism (CD), absorbance, and fluorescence were simultaneously applied while slowly unfolding our protein by increasing the concentration of a chemical denaturant, guanidine hydrochloride. This provided us information about the thermodynamic properties of the protein and several mutants which can then be interpreted to gain relative stability information among mutations. Efforts to utilize these techniques on native and mutated proteins in comparison to current scientific unfolding theories will be presented in this session.

  15. Shape coexistence at low spin in the Z = 50 region and its spectroscopic signatures

    NASA Astrophysics Data System (ADS)

    Garrett, P. E.

    2016-08-01

    Nuclei in the Z = 50 region provide excellent examples of shape coexistence, the establishment of which occurred through the use of detailed spectroscopy, based not only on γ-ray spectroscopy but also conversion electron, particle transfer, Coulomb excitation, and lifetime measurements. The evidence to date strongly suggests that the presence of coexisting shapes arises from the promotion of protons across the Z = 50 closed shell and the strong correlations arising from interplay of the pairing and quadrupole interactions. The evidence for the presence of shape coexistence in the Z = 50 region, at low spin and low excitation energies, will be presented and clues for the microscopic origin explored.

  16. A Synthetic High-Spin Oxoiron(IV) Complex: Generation, Spectroscopic Characterization, and Reactivity

    SciTech Connect

    England, J.; Martinho, M; Farquhar, E; Frisch, J; Bominaar, E; Munck, E; Que, L

    2009-01-01

    The high-yield generation of a synthetic high-spin oxoiron(IV) complex, (Fe{sup IV}(O)(TMG{sub 3}tren)){sup 2+} (TMG{sub 3}tren = 1,1,1-tris{l_brace}2-(N2-(1,1,3,3-tetramethylguanidino))ethyl{r_brace}amine), has been achieved by using the very bulky tetradentate TMG{sub 3}tren ligand, in order to both sterically protect the oxoiron(IV) moiety and enforce a trigonal bipyramidal geometry at the iron center, for which an S=2 ground state is favored.

  17. Spectroscopic Evidence for Strong Quantum Spin Fluctuations with Itinerant Character in YFe2Ge2

    DOE PAGES

    Sirica, N.; Bondino, F.; Nappini, S.; ...

    2015-03-04

    We report x-ray absorption and photoemission spectroscopy of the electronic structure in the normal state of metallic YFe2Ge2. The data reveal evidence for large fluctuating spin moments on the Fe sites, as indicated by exchange multiplets appearing in the Fe 3s core-level photoemission spectra, even though the compound does not show magnetic order. The magnitude of the multiplet splitting is comparable to that observed in the normal state of the Fe-pnictide superconductors. This shows a connection between YFe2Ge2 and the Fe-based superconductors even though it contains neither pnictogens nor chalcogens. Finally, the implication is that the chemical range of compoundsmore » showing at least one of the characteristic magnetic signatures of the Fe-based superconductors is broader than previously thought.« less

  18. Characterizing Si:P quantum dot qubits with spin resonance techniques

    PubMed Central

    Wang, Yu; Chen, Chin-Yi; Klimeck, Gerhard; Simmons, Michelle Y.; Rahman, Rajib

    2016-01-01

    Quantum dots patterned by atomically precise placement of phosphorus donors in single crystal silicon have long spin lifetimes, advantages in addressability, large exchange tunability, and are readily available few-electron systems. To be utilized as quantum bits, it is important to non-invasively characterise these donor quantum dots post fabrication and extract the number of bound electron and nuclear spins as well as their locations. Here, we propose a metrology technique based on electron spin resonance (ESR) measurements with the on-chip circuitry already needed for qubit manipulation to obtain atomic scale information about donor quantum dots and their spin configurations. Using atomistic tight-binding technique and Hartree self-consistent field approximation, we show that the ESR transition frequencies are directly related to the number of donors, electrons, and their locations through the electron-nuclear hyperfine interaction. PMID:27550779

  19. Spin-echo magnetic resonance spectroscopic imaging at 7 T with frequency-modulated refocusing pulses.

    PubMed

    Zhu, He; Soher, Brian J; Ouwerkerk, Ronald; Schär, Michael; Barker, Peter B

    2013-05-01

    Two approaches to high-resolution SENSE-encoded magnetic resonance spectroscopic imaging (MRSI) of the human brain at 7 Tesla (T) with whole-slice coverage are described. Both sequences use high-bandwidth radiofrequency pulses to reduce chemical shift displacement artifacts, SENSE-encoding to reduce scan time, and dual-band water and lipid suppression optimized for 7 T. Simultaneous B0 and transmit B1 mapping was also used for both sequences to optimize field homogeneity using high-order shimming and determine optimum radiofrequency transmit level, respectively. One sequence ("Hahn-MRSI") used reduced flip angle (90°) refocusing pulses for lower radiofrequency power deposition, while the other sequence used adiabatic fast passage refocusing pulses for improved sensitivity and reduced signal dependence on the transmit-B1 level. In four normal subjects, adiabatic fast passage-MRSI showed a signal-to-noise ratio improvement of 3.2±0.5 compared to Hahn-MRSI at the same spatial resolution, pulse repetition time, echo time, and SENSE-acceleration factor. An interleaved two-slice Hahn-MRSI sequence is also demonstrated to be experimentally feasible.

  20. Study on the interaction between Besifloxacin and bovine serum albumin by spectroscopic techniques.

    PubMed

    Yu, Xianyong; Jiang, Bingfei; Liao, Zhixi; Jiao, Yue; Yi, Pinggui

    2015-01-01

    The interaction between Besifloxacin (BFLX) and bovine serum albumin (BSA) was investigated by spectroscopic (fluorescence, UV-Vis absorption and circular dichroism) techniques under imitated physiological conditions. The experiments were conducted at different temperatures (298, 304 and 310 K) and the results showed that the BFLX caused the fluorescence quenching of BSA through a static quenching procedure. The binding constant (Ka), binding sites (n) were obtained. The corresponding thermodynamic parameters (ΔH, ΔS and ΔG) of the interaction system were calculated at different temperatures. The results revealed that the binding process was spontaneous and the acting force between BFLX and BSA were mainly electrostatic forces. According to Förster non-radiation energy transfer theory, the binding distance between BFLX and BSA was calculated to be 4.96 nm. What is more, both synchronous fluorescence and circular dichroism spectra confirmed conformational changes of BSA.

  1. Systematic toxicological analysis of drugs and poisons in biosamples by hyphenated chromatographic and spectroscopic techniques.

    PubMed

    Polettini, A

    1999-10-15

    The introduction of hyphenated chromatographic-spectroscopic techniques represented a substantial step-forward for Systematic Toxicological Analysis (STA), increasing the amount and quality of information obtainable from the analysis of a biological sample, and enhancing the possibilities of identifying unknown drugs and poisons. STA methods based either on GC-MS or on HPLC-UV published in the last decade are reviewed in this paper. The different analytical phases, i.e. sample preparation (pretreatment, extraction, derivatisation), chromatographic separation and detection/identification are examined in detail in order to emphasise the complementarity of the two approaches. In addition, the first STA method based on HPLC-MS is illustrated and some applications of TLC-UV to drug screening are also described. Finally, an overview of semi- and fully-automated STA methods is given.

  2. Electron Spin Resonance and optical absorption spectroscopic studies of manganese centers in aluminium lead borate glasses.

    PubMed

    SivaRamaiah, G; LakshmanaRao, J

    2012-12-01

    Electron Spin Resonance (ESR) and optical absorption studies of 5Al(2)O(3)+75H(3)BO(3)+(20-x)PbO+xMnSO(4) (where x=0.5, 1,1.5 and 2 mol% of MnSO(4)) glasses at room temperature have been studied. The ESR spectrum of all the glasses exhibits resonance signals with effective isotropic g values at ≈2.0, 3.3 and 4.3. The ESR resonance signal at isotropic g≈2.0 has been attributed to Mn(2+) centers in an octahedral symmetry. The ESR resonance signals at isotropic g≈3.3 and 4.3 have been attributed to the rhombic symmetry of the Mn(2+) ions. The zero-field splitting parameter (zfs) has been calculated from the intensities of the allowed hyperfine lines. The optical absorption spectrum exhibits an intense band in the visible region and it has been attributed to (5)E(g)→(5)T(2g) transition of Mn(3+)centers in an octahedral environment. The optical band gap and the Urbach energies have been calculated from the ultraviolet absorption edges.

  3. Infrared spectroscopic investigation of nuclear spin conversion in solid CH{sub 4}

    SciTech Connect

    Sugimoto, Takeru; Yamakawa, Koichiro Arakawa, Ichiro

    2015-12-14

    Infrared spectra of solid CH{sub 4} were studied in the ν{sub 3} and ν{sub 4} vibrational regions. The phase I crystal around 30 K showed broad absorption bands, whereas the phase II crystal at 6.9–10.3 K exhibited splitting of these bands after annealing above 20 K. The split peaks were assigned to the librating and almost freely rotating molecules in phase II on the basis of the peak spacings and time evolution of the peak intensities. From the quantitative analysis of the temporal changes of the R(0) and R(1) peak intensities, the relaxation rates of the numbers of molecules with J = 0 (I = 2) and J = 1 (I = 1) were determined in the temperature range of 6.9–10.3 K. We fitted the function resulting from a combination of direct and indirect relaxation processes mediated by phonons to the temperature dependence of these rates and obtained the activation energies of the indirect process: C ≃ 36 K. Since this value is higher than the energies of perturbed J = 2 states relative to the J = 1 state, we argue that the nuclear spin conversion through the J = 3 state also takes place.

  4. Infrared spectroscopic investigation of nuclear spin conversion in solid CH4

    NASA Astrophysics Data System (ADS)

    Sugimoto, Takeru; Yamakawa, Koichiro; Arakawa, Ichiro

    2015-12-01

    Infrared spectra of solid CH4 were studied in the ν3 and ν4 vibrational regions. The phase I crystal around 30 K showed broad absorption bands, whereas the phase II crystal at 6.9-10.3 K exhibited splitting of these bands after annealing above 20 K. The split peaks were assigned to the librating and almost freely rotating molecules in phase II on the basis of the peak spacings and time evolution of the peak intensities. From the quantitative analysis of the temporal changes of the R(0) and R(1) peak intensities, the relaxation rates of the numbers of molecules with J = 0 (I = 2) and J = 1 (I = 1) were determined in the temperature range of 6.9-10.3 K. We fitted the function resulting from a combination of direct and indirect relaxation processes mediated by phonons to the temperature dependence of these rates and obtained the activation energies of the indirect process: C ≃ 36 K. Since this value is higher than the energies of perturbed J = 2 states relative to the J = 1 state, we argue that the nuclear spin conversion through the J = 3 state also takes place.

  5. Nondestructive spectroscopic and imaging techniques for quality evaluation and assessment of fish and fish products.

    PubMed

    He, Hong-Ju; Wu, Di; Sun, Da-Wen

    2015-01-01

    Nowadays, people have increasingly realized the importance of acquiring high quality and nutritional values of fish and fish products in their daily diet. Quality evaluation and assessment are always expected and conducted by using rapid and nondestructive methods in order to satisfy both producers and consumers. During the past two decades, spectroscopic and imaging techniques have been developed to nondestructively estimate and measure quality attributes of fish and fish products. Among these noninvasive methods, visible/near-infrared (VIS/NIR) spectroscopy, computer/machine vision, and hyperspectral imaging have been regarded as powerful and effective analytical tools for fish quality analysis and control. VIS/NIR spectroscopy has been widely applied to determine intrinsic quality characteristics of fish samples, such as moisture, protein, fat, and salt. Computer/machine vision on the other hand mainly focuses on the estimation of external features like color, weight, size, and surface defects. Recently, by incorporating both spectroscopy and imaging techniques in one system, hyperspectral imaging cannot only measure the contents of different quality attributes simultaneously, but also obtain the spatial distribution of such attributes when the quality of fish samples are evaluated and measured. This paper systematically reviews the research advances of these three nondestructive optical techniques in the application of fish quality evaluation and determination and discuss future trends in the developments of nondestructive technologies for further quality characterization in fish and fish products.

  6. Study on the interaction of catechins with human serum albumin using spectroscopic and electrophoretic techniques

    NASA Astrophysics Data System (ADS)

    Trnková, Lucie; Boušová, Iva; Staňková, Veronika; Dršata, Jaroslav

    2011-01-01

    The interaction between eight naturally occurring flavanols (catechin, epicatechin, gallocatechin, epigallocatechin, catechin gallate, epicatechin gallate, gallocatechin gallate, and epigallocatechin gallate) and human serum albumin (HSA) has been investigated by spectroscopic (fluorescence quenching and UV-Vis absorption) and electrophoretic (native and SDS PAGE) techniques under simulated physiological conditions (pH 7.40, 37 °C). The spectroscopic results confirmed the complex formation for the tested systems. The binding constants and the number of binding sites were obtained by analysis of fluorescence data. The strongest binding affinity to HSA was found for epicatechin gallate and decreased in the order epicatechin gallate ⩾ catechin gallate > epigallocatechin gallate > gallocatechin gallate ≫ epicatechin ⩾ catechin > gallocatechin ⩾ epigallocatechin. All free energy changes possessed negative sign indicating the spontaneity of catechin-HSA systems formation. The binding distances between the donor (HSA) and the acceptors (catechins) estimated by the Förster theory revealed that non-radiation energy transfer from HSA to catechins occurred with high possibility. According to results obtained by native PAGE, the galloylated catechins increased the electrophoretic mobility of HSA, which indicated the change in the molecular charge of HSA, whilst the non-galloylated catechins caused no changes. The ability of aggregation and cross-linking of tested catechins with HSA was not proved by SDS-PAGE. The relationship between the structure characteristics of all tested catechins (e.g. presence of the galloyl moiety on the C-ring, the number of hydroxyl groups on the B-ring, and the spatial arrangement of the substituents on the C-ring) and their binding properties to HSA is discussed. The presented study contributes to the current knowledge in the area of protein-ligand binding, particularly catechin-HSA interactions.

  7. Feasibility of measuring density and temperature of laser produced plasmas using spectroscopic techniques.

    SciTech Connect

    Edens, Aaron D.

    2008-09-01

    A wide variety of experiments on the Z-Beamlet laser involve the creation of laser produced plasmas. Having a direct measurement of the density and temperature of these plasma would an extremely useful tool, as understanding how these quantities evolve in space and time gives insight into the causes of changes in other physical processes, such as x-ray generation and opacity. We propose to investigate the possibility of diagnosing the density and temperature of laser-produced plasma using temporally and spatially resolved spectroscopic techniques that are similar to ones that have been successfully fielded on other systems. Various researchers have measured the density and temperature of laboratory plasmas by looking at the width and intensity ratio of various characteristic lines in gases such as nitrogen and hydrogen, as well as in plasmas produced off of solid targets such as zinc. The plasma conditions produce two major measurable effects on the characteristic spectral lines of that plasma. The 1st is the Stark broadening of an individual line, which depends on the electron density of the plasma, with higher densities leading to broader lines. The second effect is a change in the ratio of various lines in the plasma corresponding to different ionization states. By looking at the ratio of these lines, we can gain some understanding of the plasma ionization state and consequently its temperature (and ion density when coupled with the broadening measurement). The hotter a plasma is, the higher greater the intensity of lines corresponding to higher ionization states. We would like to investigate fielding a system on the Z-Beamlet laser chamber to spectroscopically study laser produced plasmas from different material targets.

  8. A RAPID SPECTROSCOPIC TECHNIQUE FOR DETERMINING THE POTENTIAL ALPHA ENERGY CONCENTRATION OF RADON DECAY PRODUCTS

    SciTech Connect

    Revzan, K. L.; Nazaroff, W. W.

    1981-07-01

    We consider the application of alpha spectroscopy to the rapid determination of the potential alpha energy concentration (PAEC) of radon decay products indoors. Two count totals are obtained after a single counting period. The PAEC is then estimated by a linear combination of the count totals, the two coefficients being determined by analysis of the dependence of the statistical and procedural errors on the equilibrium conditions and the sampling, delay, and counting times. For a total measurement time of 11 min, the procedural error is unlikely to exceed 20% for equilibrium conditions commonly found indoors; the statistical error is less than 20% at a PAEC of 0.005 WL, assuming a product of detector efficiency and flow rate of at least 1.0 l/min. An analysis is made of techniques based on a total alpha count, and the results are compared with those obtained with the rapid spectroscopic technique; the latter is clearly preferable when the measurement time does not exceed 15 min.

  9. Application of spectroscopic techniques for the analysis of kidney stones: a pilot study

    NASA Astrophysics Data System (ADS)

    Shameem, K. M., Muhammed; Chawla, Arun; Bankapur, Aseefhali; Unnikrishnan, V. K.; Santhosh, C.

    2016-03-01

    Identification and characterization of kidney stone remains one of the important analytical tasks in the medical field. Kidney stone is a common health complication throughout the world, which may cause severe pain, obstruction and infection of urinary tract, and can lead to complete renal damage. It commonly occurs in both sexes regardless of age. Kidney stones have different composition, although each stones have a major single characteristic component. A complete understanding of a sample properties and their function can only be feasible by utilizing elemental and molecular information simultaneously. Two laser based analytical techniques; Laser Induced Breakdown spectroscopy (LIBS) and Raman spectroscopy have been used to study different types of kidney stones from different patients. LIBS and Raman spectroscopy are highly complementary spectroscopic techniques, which provide elemental and molecular information of a sample. Q-switched Nd:YAG laser at 355 nm laser having energy 17mJ per pulse at 10 Hz repetition rate was used for getting LIBS spectra. Raman measurements were carried out using a home assembled micro-Raman spectrometer. Using the recorded Raman spectra of kidney stones, we were able to differentiate different kinds of kidney stones. LIBS spectra of the same stones are showing the evidence of C, Ca, H, and O and also suggest the presence of certain pigments.

  10. DNA-binding study of anticancer drug cytarabine by spectroscopic and molecular docking techniques.

    PubMed

    Shahabadi, Nahid; Falsafi, Monireh; Maghsudi, Maryam

    2017-01-02

    The interaction of anticancer drug cytarabine with calf thymus DNA (CT-DNA) was investigated in vitro under simulated physiological conditions by multispectroscopic techniques and molecular modeling study. The fluorescence spectroscopy and UV absorption spectroscopy indicated drug interacted with CT-DNA in a groove-binding mode, while the binding constant of UV-vis and the number of binding sites were 4.0 ± 0.2 × 10(4) L mol(-1) and 1.39, respectively. The fluorimetric studies showed that the reaction between the drugs with CT-DNA is exothermic. Circular dichroism spectroscopy was employed to measure the conformational change of DNA in the presence of cytarabine. Furthermore, the drug induces detectable changes in its viscosity for DNA interaction. The molecular modeling results illustrated that cytarabine strongly binds to groove of DNA by relative binding energy of docked structure -20.61 KJ mol(-1). This combination of multiple spectroscopic techniques and molecular modeling methods can be widely used in the investigation on the interaction of small molecular pollutants and drugs with biomacromolecules for clarifying the molecular mechanism of toxicity or side effect in vivo.

  11. Enhancement of Electron Spin Echo Envelope Modulation Spectroscopic Methods to Investigate the Secondary Structure of Membrane Proteins

    PubMed Central

    Liu, Lishan; Sahu, Indra D.; Mayo, Daniel J.; McCarrick, Robert M.; Troxel, Kaylee; Zhou, Andy; Shockley, Erin; Lorigan, Gary A.

    2012-01-01

    This paper reports on a significant improvement of a new structural biology approach designed to probe the secondary structure of membrane proteins using the pulsed EPR technique of Electron Spin Echo Envelope Modulation (ESEEM) spectroscopy. Previously, we showed that we could characterize an α-helical secondary structure with ESEEM spectroscopy using a 2H-labeled Val side chain coupled with site-directed spin-labeling (SDSL). In order to further develop this new approach, molecular dynamic (MD) simulations were conducted on several different hydrophobic residues that are commonly found in membrane proteins. 2H-SL distance distributions from the MD results indicated that 2H-labeled Leu was a very strong candidate to significantly improve this ESEEM approach. In order to test this hypothesis, the secondary structure of the α-helical M2δ peptide of the acetylcholine receptor (AChR) incorporated into a bicelle was investigated with 2H-labeled Leu d10 at position 10 (i) and nitroxide spin labels positioned 1, 2, 3 and 4 residues away (denoted i+1 to i+4) with ESEEM spectroscopy. The ESEEM data reveal a unique pattern that is characteristic of an α-helix (3.6 residues per turn). Strong 2H modulation was detected for the i+3 and i+4 samples, but not for the i+2 sample. The 2H modulation depth observed for 2H-labeled d10 Leu was significantly enhanced (x4) when compared to previous ESEEM measurements that used 2H-labeled d8 Val. Computational studies indicate that deuterium nuclei on the Leu sidechain are closer to the spin label when compared to Val. The enhancement of 2H modulation and the corresponding Fourier Transform (FT) peak intensity for 2H-labeled Leu significantly reduces the ESEEM data acquisition time for Leu when compared to Val. This research demonstrates that a different 2H-labeled amino acid residue can be used as an efficient ESEEM probe further substantiating this important biophysical technique. Finally, this new method can provide pertinent

  12. The Spin Move: A Reliable and Cost-Effective Gowning Technique for the 21st Century.

    PubMed

    Ochiai, Derek H; Adib, Farshad

    2015-04-01

    Operating room efficiency (ORE) and utilization are considered one of the most crucial components of quality improvement in every hospital. We introduced a new gowning technique that could optimize ORE. The Spin Move quickly and efficiently wraps a surgical gown around the surgeon's body. This saves the operative time expended through the traditional gowning techniques. In the Spin Move, while the surgeon is approaching the scrub nurse, he or she uses the left heel as the fulcrum. The torque, which is generated by twisting the right leg around the left leg, helps the surgeon to close the gown as quickly and safely as possible. From 2003 to 2012, the Spin Move was performed in 1,725 consecutive procedures with no complication. The estimated average time was 5.3 and 7.8 seconds for the Spin Move and traditional gowning, respectively. The estimated time saving for the senior author during this period was 71.875 minutes. Approximately 20,000 orthopaedic surgeons practice in the United States. If this technique had been used, 23,958 hours could have been saved. The money saving could have been $14,374,800.00 (23,958 hours × $600/operating room hour) during the past 10 years. The Spin Move is easy to perform and reproducible. It saves operating room time and increases ORE.

  13. Intratumoral Agreement of High-Resolution Magic Angle Spinning Magnetic Resonance Spectroscopic Profiles in the Metabolic Characterization of Breast Cancer

    PubMed Central

    Park, Vivian Youngjean; Yoon, Dahye; Koo, Ja Seung; Kim, Eun-Kyung; Kim, Seung Il; Choi, Ji Soo; Park, Seho; Park, Hyung Seok; Kim, Suhkmann; Kim, Min Jung

    2016-01-01

    Abstract High-resolution magic angle spinning (HR-MAS) magnetic resonance (MR) spectroscopy data may serve as a biomarker for breast cancer, with only a small volume of tissue sample required for assessment. However, previous studies utilized only a single tissue sample from each patient. The aim of this study was to investigate whether intratumoral location and biospecimen type affected the metabolic characterization of breast cancer assessed by HR-MAS MR spectroscopy This prospective study was approved by the institutional review board and informed consent was obtained. Preoperative core-needle biopsies (CNBs), central, and peripheral surgical tumor specimens were prospectively collected under ultrasound (US) guidance in 31 patients with invasive breast cancer. Specimens were assessed with HR-MAS MR spectroscopy. The reliability of metabolite concentrations was evaluated and multivariate analysis was performed according to intratumoral location and biospecimen type. There was a moderate or higher agreement between the relative concentrations of 94.3% (33 of 35) of metabolites in the center and periphery, 80.0% (28 of 35) of metabolites in the CNB and central surgical specimens, and 82.9% (29 of 35) of metabolites between all 3 specimen types. However, there was no significant agreement between the concentrations of phosphocholine (PC) and phosphoethanolamine (PE) in the center and periphery. The concentrations of several metabolites (adipate, arginine, fumarate, glutamate, PC, and PE) had no significant agreement between the CNB and central surgical specimens. In conclusion, most HR-MAS MR spectroscopic data do not differ based on intratumoral location or biospecimen type. However, some metabolites may be affected by specimen-related variables, and caution is recommended in decision-making based solely on metabolite concentrations, particularly PC and PE. Further validation through future studies is needed for the clinical implementation of these biomarkers based

  14. A technique for measurement of vector and tensor polarization in solid spin one polarized targets

    SciTech Connect

    Kielhorn, W.F.

    1991-06-01

    Vector and tensor polarizations are explicitly defined and used to characterize the polarization states of spin one polarized targets, and a technique for extracting these polarizations from nuclear magnetic resonance (NMR) data is developed. This technique is independent of assumptions about spin temperature, but assumes the target's crystal structure induces a quadrupole interaction with the spin one particles. Analysis of the NMR signals involves a computer curve fitting algorithm implemented with a fast Fourier transform method which speeds and simplifies curve fitting algorithms used previously. For accurate curve fitting, the NMR electronic circuit must be modeled by the fitting algorithm. Details of a circuit, its model, and data collected from this circuit are given for a solid deuterated ammonia target. 37 refs., 19 figs., 3 tabs.

  15. Planetary Surface Analysis Using Fast Laser Spectroscopic Techniques: Combined Microscopic Raman, LIBS, and Fluorescence Spectroscopy

    NASA Astrophysics Data System (ADS)

    Blacksberg, J.; Rossman, G. R.; Maruyama, Y.; Charbon, E.

    2011-12-01

    In situ exploration of planetary surfaces has to date required multiple techniques that, when used together, yield important information about their formation histories and evolution. We present a time-resolved laser spectroscopic technique that could potentially collect complementary sets of data providing information on mineral structure, composition, and hydration state. Using a picosecond-scale pulsed laser and a fast time-resolved detector we can simultaneously collect spectra from Raman, Laser Induced Breakdown Spectroscopy (LIBS), and fluorescence emissions that are separated in time due to the unique decay times of each process. The use of a laser with high rep rate (40 KHz) and low pulse energy (1 μJ/pulse) allows us to rapidly collect high signal to noise Raman spectra while minimizing sample damage. Increasing the pulse energy by about an order of magnitude creates a microscopic plasma near the surface and enables the collection of LIBS spectra at an unusually high rep rate and low pulse energy. Simultaneously, broader fluorescence peaks can be detected with lifetimes varying from nanosecond to microsecond. We will present Raman, LIBS, and fluorescence spectra obtained on natural mineral samples such as sulfates, clays, pyroxenes and carbonates that are of interest for Mars mineralogy. We demonstrate this technique using a photocathode-based streak camera detector as well as a newly-developed solid state Single Photon Avalanche Diode (SPAD) sensor array based on Complementary Metal-Oxide Semiconductor (CMOS) technology. We will discuss the impact of system design and detector choice on science return of a potential planetary surface mission, with a specific focus on size, weight, power, and complexity. The research described here was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration (NASA).

  16. High resolution x-ray fluorescence spectroscopy - a new technique for site- and spin-selectivity

    SciTech Connect

    Wang, Xin

    1996-12-01

    X-ray spectroscopy has long been used to elucidate electronic and structural information of molecules. One of the weaknesses of x-ray absorption is its sensitivity to all of the atoms of a particular element in a sample. Through out this thesis, a new technique for enhancing the site- and spin-selectivity of the x-ray absorption has been developed. By high resolution fluorescence detection, the chemical sensitivity of K emission spectra can be used to identify oxidation and spin states; it can also be used to facilitate site-selective X-ray Absorption Near Edge Structure (XANES) and site-selective Extended X-ray Absorption Fine Structure (EXAFS). The spin polarization in K fluorescence could be used to generate spin selective XANES or spin-polarized EXAFS, which provides a new measure of the spin density, or the nature of magnetic neighboring atoms. Finally, dramatic line-sharpening effects by the combination of absorption and emission processes allow observation of structure that is normally unobservable. All these unique characters can enormously simplify a complex x-ray spectrum. Applications of this novel technique have generated information from various transition-metal model compounds to metalloproteins. The absorption and emission spectra by high resolution fluorescence detection are interdependent. The ligand field multiplet model has been used for the analysis of K{alpha} and K{beta} emission spectra. First demonstration on different chemical states of Fe compounds has shown the applicability of site selectivity and spin polarization. Different interatomic distances of the same element in different chemical forms have been detected using site-selective EXAFS.

  17. Integrated Analysis of the Wood Oil from Xanthocyparis vietnamensis Farjon & Hiep. by Chromatographic and Spectroscopic Techniques.

    PubMed

    Bazzali, Ophélie; Thai, Tran Huy; Hoi, Tran Minh; Khang, Nguyen Sinh; Hien, Nguyen Thi; Casanova, Joseph; Bighelli, Ange; Tomi, Félix

    2016-06-27

    In order to get better knowledge about the volatiles produced by Xanthocyparis vietnamensis, a species recently discovered in Vietnam, its wood oil has been analyzed by a combination of chromatographic (GC, CC) and spectroscopic (GC-MS, (13)C-NMR) techniques. Forty components that accounted for 87.9% of the oil composition have been identified. The composition is dominated by nootkatene (20.7%), 11,12,13-tri-nor-eremophil-1(10)-en-7-one (17.2%), γ-eudesmol (5.1%), nootkatone (4.7%), valencene (3.5%) and 13-nor-eremophil-1(10)-en-11-one (2.6%). The structure of two new compounds-10-epi-nor-γ-eudesmen-11-one and 12-hydroxy-isodihydroagarofuran-has been elucidated, while 11,12,13-tri-nor-eremophil-1(10)-en-7-ol is reported as a natural product for the first time. The composition of X. vietnamensis wood oil varied drastically from those of leaf oils, dominated by hedycaryol (34.4%), phyllocladene (37.8%) or by pimara-6(14)-15-diene (19.4%).

  18. Characterization of the binding of nevadensin to bovine serum albumin by optical spectroscopic technique

    NASA Astrophysics Data System (ADS)

    Yu, Zhaolian; Li, Daojin; Ji, Baoming; Chen, Jianjun

    2008-10-01

    Binding of nevadensin to bovine serum albumin (BSA) has been studied in detail at 298 and 310 K using spectrophotometric technique. The intrinsic fluorescence of BSA was strongly quenched by the addition of nevadensin and spectroscopic observations are mainly rationalized in terms of a static quenching process at lower concentration of nevadensin ( Cdrug/ CBSA < 1) and a combined quenching process at higher concentration of nevadensin ( Cdrug/ CBSA > 1). The binding parameters for the reaction at a pH above (7.40) or below (3.40) the isoelectric point have been calculated according to the double logarithm regression curve. The thermodynamic parameters Δ H0, Δ G0, Δ S0 at different temperatures and binding mechanism of nevadensin to BSA at pH 7.40 and 3.40 were evaluated. The binding ability of nevadensin to BSA at pH 7.40 was stronger than that at pH 3.40. Steady fluorescence, synchronous fluorescence and circular dichroism (CD) were applied to investigate protein conformation. A value of 2.15 nm for the average distance r between nevadensin (acceptor) and tryptophan residues (Trp) of BSA (donor) was derived from the fluorescence resonance energy transfer. Moreover, influence of pH on the interaction nevadensin with BSA was investigated.

  19. A computationally assisted spectroscopic technique to measure secondary electron emission coefficients in radio frequency plasmas

    NASA Astrophysics Data System (ADS)

    Daksha, M.; Berger, B.; Schuengel, E.; Korolov, I.; Derzsi, A.; Koepke, M.; Donkó, Z.; Schulze, J.

    2016-06-01

    A computationally assisted spectroscopic technique to measure secondary electron emission coefficients (γ-CAST) in capacitively-coupled radio-frequency plasmas is proposed. This non-intrusive, sensitive diagnostic is based on a combination of phase resolved optical emission spectroscopy and particle-based kinetic simulations. In such plasmas (under most conditions in electropositive gases) the spatio-temporally resolved electron-impact excitation/ionization rate features two distinct maxima adjacent to each electrode at different times within each RF period. While one maximum is the consequence of the energy gain of electrons due to sheath expansion, the second maximum is produced by secondary electrons accelerated towards the plasma bulk by the sheath electric field at the time of maximum voltage drop across the adjacent sheath. Due to these different excitation/ionization mechanisms, the ratio of the intensities of these maxima is very sensitive to the secondary electron emission coefficient γ. This sensitvity, in turn, allows γ to be determined by comparing experimental excitation profiles and simulation data obtained with various γ-coefficients. The diagnostic, tested here in a geometrically symmetric argon discharge, yields an effective secondary electron emission coefficient of γ =0.066+/- 0.01 for stainless steel electrodes.

  20. Studies on the interaction of salvianolic acid B with human hemoglobin by multi-spectroscopic techniques

    NASA Astrophysics Data System (ADS)

    Chen, Tingting; Zhu, Shajun; Cao, Hui; Shang, Yanfang; Wang, Miao; Jiang, Guoqing; Shi, Yujun; Lu, Tianhong

    2011-04-01

    The interaction between salvianolic acid B (Sal B) and human hemoglobin (HHb) under physiological conditions was investigated by UV-vis absorption, fluorescence, synchronous fluorescence and circular dichroism spectroscopic techniques. The experimental results indicate that the quenching mechanism of fluorescence of HHb by Sal B is a static quenching procedure, the binding reaction is spontaneous, and the hydrophobic interactions play a major role in binding of Sal B to HHb. Based on Förster's theory of non-radiative energy transfer, the binding distance between Sal B and the inner tryptophan residues of HHb was determined to be 2.64 nm. The synchronous fluorescence experiment revealed that Sal B can not lead to the microenvironmental changes around the Tyr and Trp residues of HHb, and the binding site of Sal B on HHb is located at α 1β 2 interface of HHb. Furthermore, the CD spectroscopy indicated the secondary structure of HHb is not changed in the presence of Sal B.

  1. Qualitative and quantitative changes in phospholipids and proteins investigated by spectroscopic techniques in animal depression model

    NASA Astrophysics Data System (ADS)

    Depciuch, J.; Sowa-Kucma, M.; Nowak, G.; Papp, M.; Gruca, P.; Misztak, P.; Parlinska-Wojtan, M.

    2017-04-01

    Depression becomes nowadays a high mortality civilization disease with one of the major causes being chronic stress. Raman, Fourier Transform Infra Red (FTIR) and Ultraviolet-Visible (UV-vis) spectroscopies were used to determine the changes in the quantity and structure of phospholipids and proteins in the blood serum of rats subjected to chronic mild stress, which is a common animal depression model. Moreover, the efficiency of the imipramine treatment was evaluated. It was found that chronic mild stress not only damages the structure of the phospholipids and proteins, but also decreases their level in the blood serum. A 5 weeks imipramine treatment did increase slightly the quantity of proteins, leaving the damaged phospholipids unchanged. Structural information from phospholipids and proteins was obtained by UV-vis spectroscopy combined with the second derivative of the FTIR spectra. Indeed, the structure of proteins in blood serum of stressed rats was normalized after imipramine therapy, while the impaired structure of phospholipids remained unaffected. These findings strongly suggest that the depression factor, which is chronic mild stress, may induce permanent (irreversible) damages into the phospholipid structure identified as shortened carbon chains. This study shows a possible new application of spectroscopic techniques in the diagnosis and therapy monitoring of depression.

  2. Spectroscopic technique with wide range of wavelength information improves near-infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Eda, Hideo; Aoki, Hiromichi; Eura, Shigeru; Ebe, Kazutoshi

    2009-02-01

    Near-infrared spectroscopy (NIRS) calculates hemoglobin parameters, such as oxygenated hemoglobin (oxyHb) and deoxygenated hemoglobin (deoxyHb) using the near-infrared light around the wavelength of 800nm. This is based on the modified-Lambert-Beer's law that changes in absorbance are proportional to changes in hemoglobin parameters. Many conventional measurement methods uses only a few wavelengths, however, in this research, basic examination of NIRS measurement was approached by acquiring wide range of wavelength information. Venous occlusion test was performed by using the blood pressure cuff around the upper arm. Pressure of 100mmHg was then applied for about 3 minutes. During the venous occlusion, the spectrum of the lower arm muscles was measured every 15 seconds, within the range of 600 to 1100nm. It was found that other wavelength bands hold information correlating to this venous occlusion task. Technique of improving the performance of NIRS measurement using the Spectroscopic Method is very important for Brain science.

  3. A computationally assisted spectroscopic technique to measure secondary electron emission coefficients in technological rf plasmas

    NASA Astrophysics Data System (ADS)

    Berger, Birk; Schulze, Julian; Daksha, Manaswi; Schuengel, Edmund; Koepke, Mark; Korolov, Ihor; Derzsi, Aranka; Donko, Zoltan

    2016-09-01

    A Computationally Assisted Spectroscopic Technique to measure secondary electron emission coefficients (y-CAST) in capacitive rf plasmas is proposed. This non-intrusive, sensitive diagnostic is based on a combination of Phase Resolved Optical Emission Spectroscopy and PIC simulations. Under most conditions in electropositive plasmas the spatio-temporally resolved electron-impact excitation rate features two distinct maxima adjacent to each electrode at different times within one rf period. One maximum is the consequence of an energy gain of the electrons due to sheath expansion. The second maximum is produced by electrons accelerated towards the plasma bulk by the sheath electric field at the time of maximum voltage drop across the sheath. Due to the different excitation mechanisms the ratio of the intensities of these maxima is very sensitive to y, which allows for its determination via comparing the experimentally measured excitation profiles with corresponding simulation data obtained with various y-coefficients. This diagnostic is tested here in a geometrically symmetric reactor, for stainless steel electrodes and argon gas. An effective secondary electron emission coefficient of y = 0.067+-0.010 is obtained, which is in excellent agreement with previous experimental results.

  4. Control-system techniques for improved departure/spin resistance for fighter aircraft

    NASA Technical Reports Server (NTRS)

    Nguyen, L. T.; Gilbert, W. P.; Ogburn, M. E.

    1980-01-01

    Some fundamental information on control system effects on controllability of highly maneuverable aircraft at high angles of attack are summarized as well as techniques for enhancing fighter aircraft departure/spin resistance using control system design. The discussion includes: (1) a brief review of pertinent high angle of attack phenomena including aerodynamics, inertia coupling, and kinematic coupling; (2) effects of conventional stability augmentation systems at high angles of attack; (3) high angle of attack control system concepts designed to enhance departure/spin resistance; and (4) the outlook for applications of these concepts to future fighters, particularly those designs which incorporate relaxed static stability.

  5. On-chip micro-coil technique for single electron spin resonance with quantum dot

    NASA Astrophysics Data System (ADS)

    Obata, T.; Pioro-Ladrière, M.; Kubo, T.; Yoshida, K.; Tokura, Y.; Tarucha, S.

    2007-12-01

    We have developed a combined setup consisting of an on-chip micro-coil and a quantum dot for implementing single electron spin resonance, which operates relevantly even at dilution refrigerator temperatures. We have examined the micro-coil performance of the high-frequency response. Capacitive coupling between the coil and the quantum dot causes photon-assisted tunneling, whose signal can overlap greatly with the electron spin resonance signal. We have developed a technique to compensate for the influence of the capacitive coupling, and checked the performance using Coulomb blockade transport.

  6. Continuous polymer nanofibers by extrusion into a viscous medium: A modified wet-spinning technique

    NASA Astrophysics Data System (ADS)

    Gorantla, M.; Boone, S. E.; El-Ashry, M.; Young, D.

    2006-02-01

    We present a wet-spinning technique capable of producing continuous polymer nanofibers. This method involves injecting a solvated polymer into a highly viscous moving medium through a microaperture. The extruded fiber moves in a predictable spiral path and is collected around a spinning mandrel which also serves to pull the extruded fiber away from the aperture. Semicontinuous, solid nanofibers of polyvinyl butyral were produced with diameters ranging from 10μmto400nm. Electron microscopy indicates that submicron fibers exhibit a ribbonlike morphology. The effect of different processing parameters on the fiber size and shape is discussed.

  7. Fast all-optical nuclear spin echo technique based on EIT

    NASA Astrophysics Data System (ADS)

    Walther, Andreas; Nilsson, Adam N.; Li, Qian; Rippe, Lars; Kröll, Stefan

    2016-08-01

    We demonstrate an all-optical Raman spin echo technique, using electromagnetically induced transparency (EIT) to create the pulses required for a spin echo sequence: initialization, pi-rotation, and readout. The first pulse of the sequence induces coherence directly from a mixed state, and the technique is used to measure the nuclear spin coherence of an inhomogeneously broadened ensemble of rare-earth ions (Pr3 +) in a crystal. The rephasing pi-rotation is shown to offer an advantage of combining the rephasing action with the operation of a phase gate, particularly useful in e.g. dynamic decoupling sequences. In contrast to many previous experiments the sequence does not require any preparatory hole burning, which greatly shortens the total duration of the sequence. The effect of the different pulses is characterized by quantum state tomography and compared with simulations. We demonstrate two applications of the technique: compensating the magnetic field across our sample by monitoring T 2 reductions from stray magnetic fields, and measuring coherence times at temperatures up to 11 K, where standard preparation techniques are difficult to implement. We explore the potential of the technique, in particular for systems with much shorter T 2, and other possible applications.

  8. [Application of Raman spectroscopic technique to the identification and investigation of Chinese ancient jades and jade artifacts].

    PubMed

    Zhao, Hong-Xia; Gan, Fu-Xi

    2009-11-01

    Laser Raman spectroscopic technique is one of the essential methods in scientific archaeological research, which belongs to the nondestructive analysis. As a very good nondestructive analysis approach, it has not been widely applied in the research of the Chinese ancient jade artifacts. First of all in the present paper the fundamentals of laser Raman spectroscopic technique and the new research progress in this field were reviewed. Secondly, the Raman spectra of five familiar jades including nephrite (mainly composed of tremolite), Xiuyan Jade (mainly composed of serpentine), Dushan Jade (mainly composed of anorthite and Zoisite), turquoise and lapis lazuli were summarized respectively. As for an example, the Raman spectra of the four Chinese ancient jade artifacts excavated from Liangzhu Site of Zhejiang Province and Yinxu Site of Anyang in Henan Province were compared with that of the nephrite sample in Hetian of Xinjiang Province. It was shown that the Raman spectroscopic technique is a good nondestructive approach to the identification and investigation of the structures and mineral composition of Chinese ancient jade artifacts. Finally, the limitations and the foreground of this technique were discussed.

  9. Electron spin echo envelope modulation studies of the Cu(II)-substituted derivative of isopenicillin N synthase: A structural and spectroscopic model

    SciTech Connect

    Feng Jiang; Peisach, J. ); Lijune Ming; Que, L. Jr. ); Chen, V.J. )

    1991-12-03

    Electron spin echo envelope modulation spectroscopy (ESEEM) was used to study the active site structure of isopenicillin N synthase (IPNS) from Cephalosporium acremonium with Cu(II) as a spectroscopic probe. Fourier transform of the simulated electron spin-echo envelope for the Cu(II)-substituted enzyme, Cu(II)IPNS, revealed two nearly magnetically equivalent, equatorially coordinated His imidazoles. The superhyperfine coupling constant, A{sub iso}, for the remote {sup 14}N of each imidazole was 1.65 MHz. The binding of substrate to the enzyme altered the magnetic coupling so that A{sub iso} is 1.30 MHz for one nitrogen and 2.16 MHz for the other. From a comparison of the ESSEM of Cu(II)IPNS in D{sub 2}O and H{sub 2}O, it is suggested that water is a ligand of Cu(II) and this is displaced upon the addition of substrate.

  10. Altered spin state equilibrium in the T309V mutant of cytochrome P450 2D6: a spectroscopic and computational study

    PubMed Central

    Bonifacio, Alois; Groenhof, André R.; Keizers, Peter H. J.; de Graaf, Chris; Commandeur, Jan N. M.; Vermeulen, Nico P. E.; Ehlers, Andreas W.; Lammertsma, Koop; Gooijer, Cees

    2007-01-01

    Cytochrome P450 2D6 (CYP2D6) is one of the most important cytochromes P450 in humans. Resonance Raman data from the T309V mutant of CYP2D6 show that the substitution of the conserved I-helix threonine situated in the enzyme’s active site perturbs the heme spin equilibrium in favor of the six-coordinated low-spin species. A mechanistic hypothesis is introduced to explain the experimental observations, and its compatibility with the available structural and spectroscopic data is tested using quantum-mechanical density functional theory calculations on active-site models for both the CYP2D6 wild type and the T309V mutant. Electronic supplementary material The online version of this article (doi:10.1007/s00775-007-0210-5) contains supplementary material, which is available to authorized users. PMID:17318599

  11. Applications of synchrotron-based spectroscopic techniques in studying nucleic acids and nucleic acid-functionalized nanomaterials

    PubMed Central

    Wu, Peiwen; Yu, Yang; McGhee, Claire E.; Tan, Li Huey

    2014-01-01

    In this review, we summarize recent progresses in the application of synchrotron-based spectroscopic techniques for nucleic acid research that takes advantage of high-flux and high-brilliance electromagnetic radiation from synchrotron sources. The first section of the review focuses on the characterization of the structure and folding processes of nucleic acids using different types of synchrotron-based spectroscopies, such as X-ray absorption spectroscopy, X-ray emission spectroscopy, X-ray photoelectron spectroscopy, synchrotron radiation circular dichroism, X-ray footprinting and small-angle X-ray scattering. In the second section, the characterization of nucleic acid-based nanostructures, nucleic acid-functionalized nanomaterials and nucleic acid-lipid interactions using these spectroscopic techniques is summarized. Insights gained from these studies are described and future directions of this field are also discussed. PMID:25205057

  12. Applications of synchrotron-based spectroscopic techniques in studying nucleic acids and nucleic acid-functionalized nanomaterials.

    PubMed

    Wu, Peiwen; Yu, Yang; McGhee, Claire E; Tan, Li Huey; Lu, Yi

    2014-12-10

    In this review, we summarize recent progress in the application of synchrotron-based spectroscopic techniques for nucleic acid research that takes advantage of high-flux and high-brilliance electromagnetic radiation from synchrotron sources. The first section of the review focuses on the characterization of the structure and folding processes of nucleic acids using different types of synchrotron-based spectroscopies, such as X-ray absorption spectroscopy, X-ray emission spectroscopy, X-ray photoelectron spectroscopy, synchrotron radiation circular dichroism, X-ray footprinting and small-angle X-ray scattering. In the second section, the characterization of nucleic acid-based nanostructures, nucleic acid-functionalized nanomaterials and nucleic acid-lipid interactions using these spectroscopic techniques is summarized. Insights gained from these studies are described and future directions of this field are also discussed.

  13. Applications of synchrotron-based spectroscopic techniques in studying nucleic acids and nucleic acid-functionalized nanomaterials

    SciTech Connect

    Wu, Peiwen; Yu, Yang; McGhee, Claire E.; Tan, Li Huey; Lu, Yi

    2014-09-10

    In this paper, we summarize recent progress in the application of synchrotron-based spectroscopic techniques for nucleic acid research that takes advantage of high-flux and high-brilliance electromagnetic radiation from synchrotron sources. The first section of the review focuses on the characterization of the structure and folding processes of nucleic acids using different types of synchrotron-based spectroscopies, such as X-ray absorption spectroscopy, X-ray emission spectroscopy, X-ray photoelectron spectroscopy, synchrotron radiation circular dichroism, X-ray footprinting and small-angle X-ray scattering. In the second section, the characterization of nucleic acid-based nanostructures, nucleic acid-functionalized nanomaterials and nucleic acid-lipid interactions using these spectroscopic techniques is summarized. Insights gained from these studies are described and future directions of this field are also discussed.

  14. Advances in Understanding the Molecular Structures and Functionalities of Biodegradable Zein-Based Materials Using Spectroscopic Techniques: A Review.

    PubMed

    Turasan, Hazal; Kokini, Jozef L

    2017-02-13

    Zein's amphiphilic properties, film forming capability, and biodegradability make it a highly demanded polymer for fabrication of packaging materials, production of drug carrier nanoparticles, scaffolds in tissue engineering, and formation of biodegradable platforms for biosensors including microfluidic devices. Zein properties can be improved by chemical modifications, which are often analyzed with spectroscopic techniques. However, there is not a consensus on the structure of zein. For this reason, in this Review the aim is to compile the recent studies conducted on zein-based products and compare them under five main spectroscopic techniques: Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, circular dichroism (CD), X-ray diffraction (XRD) and atomic force microscopy (AFM). This Review serves as a library of recent zein studies and helps readers to have a better perception of contradictions in the literature to take their studies one step further.

  15. Applications of synchrotron-based spectroscopic techniques in studying nucleic acids and nucleic acid-functionalized nanomaterials

    DOE PAGES

    Wu, Peiwen; Yu, Yang; McGhee, Claire E.; ...

    2014-09-10

    In this paper, we summarize recent progress in the application of synchrotron-based spectroscopic techniques for nucleic acid research that takes advantage of high-flux and high-brilliance electromagnetic radiation from synchrotron sources. The first section of the review focuses on the characterization of the structure and folding processes of nucleic acids using different types of synchrotron-based spectroscopies, such as X-ray absorption spectroscopy, X-ray emission spectroscopy, X-ray photoelectron spectroscopy, synchrotron radiation circular dichroism, X-ray footprinting and small-angle X-ray scattering. In the second section, the characterization of nucleic acid-based nanostructures, nucleic acid-functionalized nanomaterials and nucleic acid-lipid interactions using these spectroscopic techniques is summarized. Insightsmore » gained from these studies are described and future directions of this field are also discussed.« less

  16. Determination of lipid content of oleaginous microalgal biomass by NMR spectroscopic and GC-MS techniques.

    PubMed

    Sarpal, Amarijt S; Teixeira, Claudia M L L; Silva, Paulo R M; Lima, Gustavo M; Silva, Samantha R; Monteiro, Thays V; Cunha, Valnei S; Daroda, Romeu J

    2015-05-01

    Direct methods based on (1)H NMR spectroscopic techniques have been developed for the determination of neutral lipids (triglycerides and free fatty acids) and polar lipids (glyceroglycolipids/phospholipids) in the solvent extracts of oleaginous microalgal biomasses cultivated on a laboratory scale with two species in different media. The chemical shift assignments observed in the (1)H and (13)C NMR spectra corresponding to unsaturated (C18:N, N = 1-3, C20:3, C20:5, C22:6, epoxy) and saturated (C14-C18) fatty acid ester components in a complex matrix involving overlapped resonances have been unambiguously confirmed by the application of 2D NMR spectroscopy (total correlation spectroscopy and heteronuclear single quantum coherence-total correlation spectroscopy). The study of the effect of a polar lipid matrix on the determination of neutral lipids by an internal reference blending process by a systematic designed experimental protocol has provided absolute quantification. The fatty acid composition of algal extracts was found to be similar to that of vegetable oils containing saturated (C16-C18:0) and unsaturated (C18:N, N = 1-3, C20:N, N = 3-4, C22:6) fatty acids as confirmed by NMR spectroscopy and gas chromatography-mass spectrometry analyses. The NMR methods developed offer great potential for rapid screening of algal strains for generation of algal biomass with the desired lipid content, quality, and potential for biodiesel and value-added polyunsaturated fatty acids in view of the cost economics of the overall cost of generation of the biomass.

  17. Electron spin-echo techniques for the study of protein motion

    NASA Astrophysics Data System (ADS)

    Kar, Leela; Johnson, Michael E.; Bowman, Michael K.

    Electron spin-echo (ESE) spectroscopy has been used to make the first direct measurements of spin-spin relaxation times of a spin-labeled protein at physiological temperatures. Results from experiments using maleimide-labeled deoxygenated hemoglobin (dHb) from individuals homozygous for sickle cell anemia (dHbS) have been compared with those from control experiments using dHb from normal adults (dHbA). Hb "immobilized" by ammonium sulfate precipitation and by siloxane polymer entrapment have been studied for a suitable "rigid" reference. Two-dimensional ESE (2D-ESE) experiments have been performed using all of these systems. The 2D contour plots show that 2D-ESE is sensitive to the slow motion of dHbS polymers and can differentiate it from both that of immobilized Hb and of HbA molecules in solution at the same temperature and concentration. More importantly, the 2D-ESE technique enables one to select for slower motion and thereby extract the dHbS polymer signal from the total signal generated by the heterogeneous system containing dHbS molecules in solution as well as in the polymer. Computer simulations using current slow motional theories show that detailed motional and structural information may be obtained by such studies. The considerable potential of 2D-ESE spectroscopy in the study of macromolecular motion is illustrated by comparing 2D-ESE with the nonlinear technique of saturation transfer electron paramagnetic resonance.

  18. Pseudo-continuous arterial spin labeling technique for measuring CBF dynamics with high temporal resolution.

    PubMed

    Silva, A C; Kim, S G

    1999-09-01

    Cerebral blood flow (CBF) can be measured noninvasively with nuclear magnetic resonance (NMR) by using arterial water as an endogenous perfusion tracer. However, the arterial spin labeling (ASL) techniques suffer from poor temporal resolution due to the need to wait for the exchange of labeled arterial spins with tissue spins to produce contrast. In this work, a new ASL technique is introduced, which allows the measurement of CBF dynamics with high temporal and spatial resolution. This novel method was used in rats to determine the dynamics of CBF changes elicited by somatosensory stimulation with a temporal resolution of 108 ms. The onset time of the CBF response was 0.6 +/- 0.4 sec (mean +/- SD) after onset of stimulation (n = 10). The peak response was observed 4.4 +/- 3.7 sec (mean +/- SD) after stimulation began. These results are in excellent agreement with previous data obtained with invasive techniques, such as laser-Doppler flowmetry and hydrogen clearance, and suggest the appropriateness of this novel technique to probe CBF dynamics in functional and pathological studies with high temporal and spatial resolution. Magn Reson Med 42:425-429, 1999.

  19. Microwave band on-chip coil technique for single electron spin resonance in a quantum dot

    NASA Astrophysics Data System (ADS)

    Obata, Toshiaki; Pioro-Ladrière, Michel; Kubo, Toshihiro; Yoshida, Katsuharu; Tokura, Yasuhiro; Tarucha, Seigo

    2007-10-01

    Microwave band on-chip microcoils are developed for the application to single electron spin resonance measurement with a single quantum dot. Basic properties such as characteristic impedance and electromagnetic field distribution are examined for various coil designs by means of experiment and simulation. The combined setup operates relevantly in the experiment at dilution temperature. The frequency responses of the return loss and Coulomb blockade current are examined. Capacitive coupling between a coil and a quantum dot causes photon assisted tunneling, whose signal can greatly overlap the electron spin resonance signal. To suppress the photon assisted tunneling effect, a technique for compensating for the microwave electric field is developed. Good performance of this technique is confirmed from measurement of Coulomb blockade oscillations.

  20. Radio-controlled model design and testing techniques for stall/spin evaluation of general-aviation aircraft

    NASA Technical Reports Server (NTRS)

    Burk, S. M., Jr.; Wilson, C. F., Jr.

    1975-01-01

    A relatively inexpensive radio-controlled model stall/spin test technique was developed. Operational experiences using the technique are presented. A discussion of model construction techniques, spin-recovery parachute system, data recording system, and movie camera tracking system is included. Also discussed are a method of measuring moments of inertia, scaling of engine thrust, cost and time required to conduct a program, and examples of the results obtained from the flight tests.

  1. Accurate spectroscopic calculations of the 14 Λ-S and 30 Ω states of BF+ cation including the spin-orbit coupling effect

    NASA Astrophysics Data System (ADS)

    Zhu, Wenjie; Shi, Deheng; Sun, Jinfeng; Zhu, Zunlue

    2017-01-01

    This paper studied the potential energy curves of 30 Ω states yielded from the 14 Λ-S states (X2Σ+, 12Π, 22Π, 32Π, 12Σ-, 22Σ+, 32Σ+, 12Δ, 14Σ-, 14Σ+, 24Σ+, 14Π, 24Π, and 14Δ) of the BF+ cation. The potential energy curves were calculated for internuclear separations from approximately 0.08 to 1.1 nm using the CASSCF method, which was followed by the icMRCI approach with the aug-cc-pV6Z basis set. Of these 14 Λ-S states, the 24Σ+ and 24Π states were repulsive. The 22Π and 32Π states had double wells. The avoided crossings were found between the 12Π and the 22Π state, and between the 32Π and the 42Π state. The 12Π, 22Π, 32Π, and 14Π states were inverted with the spin-orbit coupling effect taken into account. The 14Π state and the second wells of 22Π and 32Π states were weakly bound. Each of the 12Π, 22Π, and 32Π states had one barrier. The potential energy curves of all the Λ-S and Ω states were extrapolated to the complete basis set limit. Core-valence correlation and scalar relativistic corrections were included at the level of an aug-cc-pV5Z basis set. The spin-orbit coupling effect was included by the state interaction approach with the Breit-Pauli Hamiltonian and the all-electron cc-pCV5Z set. The spectroscopic parameters were determined and compared with available experimental and other theoretical ones. The spin-orbit coupling effect on the spectroscopic parameters was evaluated in detail. Comparison with available experimental data show that the methodology used in this paper is highly accurate for this system.

  2. New spectroscopic data, spin-orbit functions, and global analysis of data on the A 1Sigmau+ and b 3Piu states of Na2.

    PubMed

    Qi, P; Bai, J; Ahmed, E; Lyyra, A M; Kotochigova, S; Ross, A J; Effantin, C; Zalicki, P; Vigué, J; Chawla, G; Field, R W; Whang, T-J; Stwalley, W C; Knöckel, H; Tiemann, E; Shang, J; Li, L; Bergeman, T

    2007-07-28

    The lowest electronically excited states of Na2 are of interest as intermediaries in the excitation of higher states and in the development of methods for producing cold molecules. We have compiled previously obtained spectroscopic data on the A 1Sigmau+ and b 3Piu states of Na2 from about 20 sources, both published and unpublished, together with new sub-Doppler linewidth measurements of about 15,000 A<--X transitions using polarization spectroscopy. We also present new ab initio results for the diagonal and off-diagonal spin-orbit functions. The discrete variable representation is used in conjunction with Hund's case a potentials plus spin-orbit effects to model data extending from v=0 to very close to the 3 2S+3 2P12 limit. Empirical estimates of the spin-orbit functions agree well with the ab initio functions for the accessible values of R. The potential function for the A state includes an exchange potential for S+P atoms, with a fitted coefficient somewhat larger than the predicted value. Observed and calculated term values are presented in an auxiliary (EPAPS) file as a database for future studies on Na2.

  3. Observation of the origin of d0 magnetism in ZnO nanostructures using X-ray-based microscopic and spectroscopic techniques.

    PubMed

    Singh, Shashi B; Wang, Yu-Fu; Shao, Yu-Cheng; Lai, Hsuan-Yu; Hsieh, Shang-Hsien; Limaye, Mukta V; Chuang, Chen-Hao; Hsueh, Hung-Chung; Wang, Hsaiotsu; Chiou, Jau-Wern; Tsai, Hung-Ming; Pao, Chih-Wen; Chen, Chia-Hao; Lin, Hong-Ji; Lee, Jyh-Fu; Wu, Chun-Te; Wu, Jih-Jen; Pong, Way-Faung; Ohigashi, Takuji; Kosugi, Nobuhiro; Wang, Jian; Zhou, Jigang; Regier, Tom; Sham, Tsun-Kong

    2014-08-07

    Efforts have been made to elucidate the origin of d(0) magnetism in ZnO nanocactuses (NCs) and nanowires (NWs) using X-ray-based microscopic and spectroscopic techniques. The photoluminescence and O K-edge and Zn L3,2-edge X-ray-excited optical luminescence spectra showed that ZnO NCs contain more defects than NWs do and that in ZnO NCs, more defects are present at the O sites than at the Zn sites. Specifically, the results of O K-edge scanning transmission X-ray microscopy (STXM) and the corresponding X-ray-absorption near-edge structure (XANES) spectroscopy demonstrated that the impurity (non-stoichiometric) region in ZnO NCs contains a greater defect population than the thick region. The intensity of O K-edge STXM-XANES in the impurity region is more predominant in ZnO NCs than in NWs. The increase in the unoccupied (occupied) density of states at/above (at/below) the conduction-band minimum (valence-band maximum) or the Fermi level is related to the population of defects at the O sites, as revealed by comparing the ZnO NCs to the NWs. The results of O K-edge and Zn L3,2-edge X-ray magnetic circular dichroism demonstrated that the origin of magnetization is attributable to the O 2p orbitals rather than the Zn d orbitals. Further, the local density approximation (LDA) + U verified that vacancies in the form of dangling or unpaired 2p states (due to Zn vacancies) induced a significant local spin moment in the nearest-neighboring O atoms to the defect center, which was determined from the uneven local spin density by analyzing the partial density of states of O 2p in ZnO.

  4. Analysis of space radiation effects in gallium arsenide and cadmium selenide semiconductor samples using luminescence spectroscopic techniques. Master's thesis

    SciTech Connect

    Shaffer, B.L.

    1990-12-01

    Analysis of space radiation effects in gallium arsenide and cadmium selenide semiconductor samples using luminescence spectroscopic techniques. The M0006 semiconductor samples were placed into a 28.5 degree inclination, 480 km altitude, near-circular orbit aboard the Long Duration Exposure Facility satellite and exposed to direct space environment for a period of 11 months, and were shielded by 0.313 inches of aluminum for another 58 months. The samples were examined for changes using cathodoluminescence and photoluminescence in various wavelength regions from 0.5 to 1.8 micrometers. Samples were cooled to approximately 10 degrees Kelvin in a vacuum of 10-8. (JS)

  5. Coupling spectroscopic and chromatographic techniques for evaluation of the depositional history of hydrocarbons in a subtropical estuary.

    PubMed

    Martins, César C; Doumer, Marta E; Gallice, Wellington C; Dauner, Ana Lúcia L; Cabral, Ana Caroline; Cardoso, Fernanda D; Dolci, Natiely N; Camargo, Luana M; Ferreira, Paulo A L; Figueira, Rubens C L; Mangrich, Antonio S

    2015-10-01

    Spectroscopic and chromatographic techniques can be used together to evaluate hydrocarbon inputs to coastal environments such as the Paranaguá estuarine system (PES), located in the SW Atlantic, Brazil. Historical inputs of aliphatic hydrocarbons (AHs) and polycyclic aromatic hydrocarbons (PAHs) were analyzed using two sediment cores from the PES. The AHs were related to the presence of biogenic organic matter and degraded oil residues. The PAHs were associated with mixed sources. The highest hydrocarbon concentrations were related to oil spills, while relatively low levels could be attributed to the decrease in oil usage during the global oil crisis. The results of electron paramagnetic resonance were in agreement with the absolute AHs and PAHs concentrations measured by chromatographic techniques, while near-infrared spectroscopy results were consistent with unresolved complex mixture (UCM)/total n-alkanes ratios. These findings suggest that the use of a combination of techniques can increase the accuracy of assessment of contamination in sediments.

  6. Development and Quantification of UV-Visible and Laser Spectroscopic Techniques for Materials Accountability and Process Control

    SciTech Connect

    Ken Czerwinski; Phil Weck; Frederic Poineau

    2010-12-29

    Ultraviolet-Visible Spectroscopy (UV-Visible) and Time Resolved Laser Fluorescence Spectroscopy (TRLFS) optical techniques can permit on-line, real-time analysis of the actinide elements in a solvent extraction process. UV-Visible and TRLFS techniques have been used for measuring the speciation and concentration of the actinides under laboratory conditions. These methods are easily adaptable to multiple sampling geometries, such as dip probes, fiber-optic sample cells, and flow-through cell geometries. To fully exploit these techniques for GNEP applications, the fundamental speciation of the target actinides and the resulting influence on 3 spectroscopic properties must be determined. Through this effort detection limits, process conditions, and speciation of key actinide components can be establish and utilized in a range of areas of interest to GNEP, especially in areas related to materials accountability and process control.

  7. Imaging of Heterogeneous Materials with a Turbo Spin Echo Single-Point Imaging Technique

    NASA Astrophysics Data System (ADS)

    Beyea, Steven D.; Balcom, Bruce J.; Mastikhin, Igor V.; Bremner, Theodore W.; Armstrong, Robin L.; Grattan-Bellew, Patrick E.

    2000-06-01

    A magnetic resonance imaging method is presented for imaging of heterogeneous broad linewidth materials. This method allows for distortionless relaxation weighted imaging by obtaining multiple phase encoded k-space data points with each RF excitation pulse train. The use of this method, turbo spin echo single-point imaging-(turboSPI), leads to decreased imaging times compared to traditional constant-time imaging techniques, as well as the ability to introduce spin-spin relaxation contrast through the use of longer effective echo times. Imaging times in turboSPI are further decreased through the use of low flip angle steady-state excitation. Two-dimensional images of paramagnetic doped agarose phantoms were obtained, demonstrating the contrast and resolution characteristics of the sequence, and a method for both amplitude and phase deconvolution was demonstrated for use in high-resolution turboSPI imaging. Three-dimensional images of a partially water-saturated porous volcanic aggregate (T2L ≈ 200 ms, Δν1/2 ≈ 2500 Hz) contained in a hardened white Portland cement matrix (T2L ≈ 0.5 ms, Δν1/2 ≈ 2500 Hz) and a water-saturated quartz sand (T2 ≈ 300 ms, T2* ≈ 800 μs) are shown.

  8. Laser-spectroscopic measurement techniques for hypersonic, turbulent wind tunnel flows

    NASA Technical Reports Server (NTRS)

    Mckenzie, Robert L.; Fletcher, Douglas G.

    1992-01-01

    A review is given of the nature, present status, and capabilities of two laser spectroscopic methods for the simultaneous measurement of temperature, density, and their fluctuations owing to turbulence in high speed wind tunnel flows. One method is based on the two frequency excitation of nitric oxide seeded into a nitrogen flow, using tunable dye lasers. The second, more recent method relies on the excitation of oxygen in air flows using a tunable, ArF excimer laser. Signal are obtained from both the laser induced fluorescence and from Raman scattering of the same laser pulse. Measurements are demonstrated in the turbulent boundary layer of a Mach-2 channel flow.

  9. a Technique to Calibrate Neutron-Proton Elastic Scattering Spin Observables Near 183 Mev

    NASA Astrophysics Data System (ADS)

    Bowyer, Theodore William

    Free neutron-proton scattering is one of the most fundamental reactions we can study in the field of nuclear physics, yet the n-p scattering data base is quite sparse. The data that does exist is often plagued by systematic uncertainties associated with the determination of beam and/or target polarizations. In contrast, there is an abundance of high quality, high statistics p-p elastic scattering data. We report on a technique which we have developed which exploits the high quality of the p-p data to calibrate n-p elastic scattering spin observables by simultaneous measurement of vec n-vec p and p-vec p elastic scattering by bombarding a polarized proton target with a mixed beam of polarized neutrons and protons. This technique has allowed us to calibrate the n-p elastic spin observables at 183 MeV: the beam and target analyzing powers A _{n}(theta_{p}),A _{p}(theta p), and the spin correlation coefficient, C_{NN}( theta_{p}). The mixed secondary beam was produced by bombarding a liquid deuterium target with a 200 MeV beam of polarized protons. The experiment was preformed in the Polarized Neutron Facility at the Indiana University Cyclotron Facility utilizing a left-right symmetric detection system, sensitive to both scattered protons and neutrons, and spanned the laboratory angular range of 24^circ to 62^circ. We identified free scattering events through a number of kinematic correlations. We compare our results to various phase shift calculations and potential models and examine the sensitivity of magnitude of various phase shifts results to the inclusion of our data into the n-p data base.

  10. Artificial tektites: an experimental technique for capturing the shapes of spinning drops

    NASA Astrophysics Data System (ADS)

    Baldwin, Kyle A.; Butler, Samuel L.; Hill, Richard J. A.

    2015-01-01

    Determining the shapes of a rotating liquid droplet bound by surface tension is an archetypal problem in the study of the equilibrium shapes of a spinning and charged droplet, a problem that unites models of the stability of the atomic nucleus with the shapes of astronomical-scale, gravitationally-bound masses. The shapes of highly deformed droplets and their stability must be calculated numerically. Although the accuracy of such models has increased with the use of progressively more sophisticated computational techniques and increases in computing power, direct experimental verification is still lacking. Here we present an experimental technique for making wax models of these shapes using diamagnetic levitation. The wax models resemble splash-form tektites, glassy stones formed from molten rock ejected from asteroid impacts. Many tektites have elongated or `dumb-bell' shapes due to their rotation mid-flight before solidification, just as we observe here. Measurements of the dimensions of our wax `artificial tektites' show good agreement with equilibrium shapes calculated by our numerical model, and with previous models. These wax models provide the first direct experimental validation for numerical models of the equilibrium shapes of spinning droplets, of importance to fundamental physics and also to studies of tektite formation.

  11. Accurate calculations on 9 Λ-S and 28 Ω states of NSe radical in the gas phase: Potential energy curves, spectroscopic parameters and spin-orbit couplings

    NASA Astrophysics Data System (ADS)

    Shi, Deheng; Li, Peiling; Sun, Jinfeng; Zhu, Zunlue

    2014-01-01

    The potential energy curves (PECs) of 28 Ω states generated from 9 Λ-S states (X2Π, 14Π, 16Π, 12Σ+, 14Σ+, 16Σ+, 14Σ-, 24Π and 14Δ) are studied for the first time using an ab initio quantum chemical method. All the 9 Λ-S states correlate to the first two dissociation limits, N(4Su) + Se(3Pg) and N(4Su) + Se(3Dg), of NSe radical. Of these Λ-S states, the 16Σ+, 14Σ+, 16Π, 24Π and 14Δ are found to be rather weakly bound states. The 12Σ+ is found to be unstable and has double wells. And the 16Σ+, 14Σ+, 14Π and 16Π are found to be the inverted ones with the SO coupling included. The PEC calculations are made by the complete active space self-consistent field method, which is followed by the internally contracted multireference configuration interaction approach with the Davidson modification. The spin-orbit coupling is accounted for by the state interaction approach with the Breit-Pauli Hamiltonian. The convergence of the present calculations is discussed with respect to the basis set and the level of theory. Core-valence correlation corrections are included with a cc-pCVTZ basis set. Scalar relativistic corrections are calculated by the third-order Douglas-Kroll Hamiltonian approximation at the level of a cc-pV5Z basis set. All the PECs are extrapolated to the complete basis set limit. The variation with internuclear separation of spin-orbit coupling constants is discussed in brief for some Λ-S states with one shallow well on each PEC. The spectroscopic parameters of 9 Λ-S and 28 Ω states are determined by fitting the first ten vibrational levels whenever available, which are calculated by solving the rovibrational Schrödinger equation with Numerov's method. The splitting energy in the X2Π Λ-S state is determined to be about 864.92 cm-1, which agrees favorably with the measurements of 891.80 cm-1. Moreover, other spectroscopic parameters of Λ-S and Ω states involved here are also in fair agreement with available measurements. It

  12. Application of a system modification technique to dynamic tuning of a spinning rotor blade

    NASA Technical Reports Server (NTRS)

    Spain, C. V.

    1987-01-01

    An important consideration in the development of modern helicopters is the vibratory response of the main rotor blade. One way to minimize vibration levels is to ensure that natural frequencies of the spinning main rotor blade are well removed from integer multiples of the rotor speed. A technique for dynamically tuning a finite-element model of a rotor blade to accomplish that end is demonstrated. A brief overview is given of the general purpose finite element system known as Engineering Analysis Language (EAL) which was used in this work. A description of the EAL System Modification (SM) processor is then given along with an explanation of special algorithms developed to be used in conjunction with SM. Finally, this technique is demonstrated by dynamically tuning a model of an advanced composite rotor blade.

  13. New Spectroscopic Technique Based on Coaddition of Surface Brightness Fluctuations: NGC 4449 and its Stellar Tidal Stream

    NASA Astrophysics Data System (ADS)

    Toloba, Elisa; Guhathakurta, Puragra; Romanowsky, Aaron J.; Brodie, Jean P.; Martínez-Delgado, David; Arnold, Jacob A.; Ramachandran, Neel; Theakanath, Kuriakose

    2016-06-01

    We present a new spectroscopic technique based in part on targeting the upward fluctuations of the surface brightness for studying the internal stellar kinematics and metallicities of galaxies of low surface brightness effects both to galaxies and streams beyond the Local Group. The distance to these systems makes them unsuitable for targeting individual red giant branch (RGB) stars (tip of RGB at I≳ 24 mag) and their surface brightness is too low ({μ }r≳ 25 mag arcsec-2) for integrated light spectroscopic measurements. This technique overcomes these two problems by targeting individual objects that are brighter than the tip of the RGB. We apply this technique to the star-forming dwarf galaxy NGC 4449 and its stellar stream. We use Keck/DEIMOS data to measure the line-of-sight radial velocity out to ˜7 kpc in the east side of the galaxy and ˜8 kpc along the stream. We find that the two systems are likely gravitationally bound to each other and have heliocentric radial velocities of 227.3 ± 10.7 km s-1 and 225.8 ± 16.0 km s-1, respectively. Neither the stream nor the near half of the galaxy shows a significant velocity gradient. We estimate the stellar metallicity of the stream based on the equivalent width of its calcium triplet lines and find [Fe/H] =\\quad -1.37+/- 0.41, which is consistent with the metallicity-luminosity relation for dwarf galaxies in the Local Group. Whether the stream's progenitor was moderately or severely stripped cannot be constrained with this uncertainty in metallicity. We demonstrate that this new technique can be used to measure the kinematics and (possibly) the metallicity of the numerous faint satellites and stellar streams in the halos of nearby (˜4 Mpc) galaxies.

  14. Spin injection and detection in lanthanum- and niobium-doped SrTiO3 using the Hanle technique.

    PubMed

    Han, Wei; Jiang, Xin; Kajdos, Adam; Yang, See-Hun; Stemmer, Susanne; Parkin, Stuart S P

    2013-01-01

    There has been much interest in the injection and detection of spin-polarized carriers in semiconductors for the purposes of developing novel spintronic devices. Here we report the electrical injection and detection of spin-polarized carriers into Nb-doped strontium titanate single crystals and La-doped strontium titanate epitaxial thin films using MgO tunnel barriers and the three-terminal Hanle technique. Spin lifetimes of up to ~100 ps are measured at room temperature and vary little as the temperature is decreased to low temperatures. However, the mobility of the strontium titanate has a strong temperature dependence. This behaviour and the carrier doping dependence of the spin lifetime suggest that the spin lifetime is limited by spin-dependent scattering at the MgO/strontium titanate interfaces, perhaps related to the formation of doping induced Ti(3+). Our results reveal a severe limitation of the three-terminal Hanle technique for measuring spin lifetimes within the interior of the subject material.

  15. Binding studies of lophirone B with bovine serum albumin (BSA): Combination of spectroscopic and molecular docking techniques

    NASA Astrophysics Data System (ADS)

    Chaves, Otávio Augusto; da Silva, Veridiana A.; Sant'Anna, Carlos Maurício R.; Ferreira, Aurélio B. B.; Ribeiro, Tereza Auxiliadora N.; de Carvalho, Mário G.; Cesarin-Sobrinho, Dari; Netto-Ferreira, José Carlos

    2017-01-01

    The interaction between the transport protein bovine serum albumin (BSA) and the natural product lophirone B, was investigated by spectroscopic techniques combined with a computational method (molecular docking). From the KSV and kq values it was concluded that lophirone B quenches the fluorescence of BSA by dynamic and static mechanisms. The Ka values, of the order of 104 M-1, and the number of binding sites (n ≈ 1), indicate that the binding is moderate and there is just one main binding site in BSA for lophirone B. The negative ΔG° values are in accordance with the spontaneity of the process and the positive ΔH° and ΔS° values indicate that the binding is entropically driven; the main binding forces for the association BSA:lophirone B are probably lipophilic interactions. Circular dichroism (CD) studies show there is not a significant perturbation on the secondary structure of the albumin upon the binding process. In order to better understand the spectroscopic results, a computational method was applied: molecular docking suggests Trp-213 site, as the main binding site for the ligand. Lophirone B seems to be exposed to the aqueous media as well as accommodated inside the protein cavity, resulting in a moderate affinity for the albumin. The Arg-198, His-287, Lys-294 and Lys-439 residues are interacting via hydrogen bonding with lophirone B, whereas the interaction with Trp-213 residue occurs through a lipophilic interaction.

  16. Technique to determine location of radio sources from measurements taken on spinning spacecraft

    NASA Technical Reports Server (NTRS)

    Fainberg, J.

    1979-01-01

    The procedure developed to extract average source direction and average source size from spin-modulated radio astronomy data measured on the IMP-6 spacecraft is described. Because all measurements are used, rather than just finding maxima or minima in the data, the method is very sensitive, even in the presence of large amounts of noise. The technique is applicable to all experiments with directivity characteristics. It is suitable for onboard processing on satellites to reduce the data flow to Earth. The application to spin-modulated nonpolarized radio astronomy data is made and includes the effects of noise, background, and second source interference. The analysis was tested with computer simulated data and the results agree with analytic predictions. Applications of this method with IMP-6 radio data have led to: (1) determination of source positions of traveling solar radio bursts at large distances from the Sun; (2) mapping of magnetospheric radio emissions by radio triangulation; and (3) detection of low frequency radio emissions from Jupiter and Saturn.

  17. Study on the interaction characteristics of cefamandole with bovine serum albumin by spectroscopic technique.

    PubMed

    Wang, Qian; Liu, Xuyang; Su, Ming; Shi, Zhihong; Sun, Hanwen

    2015-02-05

    The interaction of cefamandole with bovine serum albumin (BSA) was studied by fluorescence quenching in combination with UV-Vis spectroscopic method under near physiological conditions. The fluorescence quenching rate constants and binding constants for BSA-cefamandole system were determined at different temperatures. The fluorescence quenching of BSA by cefamandole is due to static quenching and energy transfer. The results of thermodynamic parameters, ΔH (-268.0 kJ mol(-1)), ΔS (-810.0 J mol(-1) K(-1)) and ΔG (-26.62 to -8.52 kJ mol(-1)), indicated that van der Waals interaction and hydrogen bonding played a major role for cefamandole-BSA association. The competitive experiments demonstrated that the primary binding site of cefamandole on BSA was located at site III in sub-domain IIIA of BSA. The distance between cefamandole and a tryptophane unit was estimated to be 1.18 nm based on the Förster resonance energy transfer theory. The binding constant (KA) of BSA-cefamandole at 298 K was 2.239×10(4) L mol(-1). Circular dichroism spectra, synchronous fluorescence and three-dimensional fluorescence studies showed that the presence of cefamandole could change the conformation of BSA during the binding process.

  18. Molecular structure and spectroscopic characterization of Carbamazepine with experimental techniques and DFT quantum chemical calculations

    NASA Astrophysics Data System (ADS)

    Suhasini, M.; Sailatha, E.; Gunasekaran, S.; Ramkumaar, G. R.

    2015-04-01

    A systematic vibrational spectroscopic assignment and analysis of Carbamazepine has been carried out by using FT-IR, FT-Raman and UV spectral data. The vibrational analysis were aided by electronic structure calculations - ab initio (RHF) and hybrid density functional methods (B3LYP) performed with standard basis set 6-31G(d,p). Molecular equilibrium geometries, electronic energies, natural bond order analysis, harmonic vibrational frequencies and IR intensities have been computed. A detailed interpretation of the vibrational spectra of the molecule has been made on the basis of the calculated Potential Energy Distribution (PED) by VEDA program. UV-visible spectrum of the compound was also recorded and the electronic properties, such as HOMO and LUMO energies and λmax were determined by HF/6-311++G(d,p) Time-Dependent method. The thermodynamic functions of the title molecule were also performed using the RHF and DFT methods. The restricted Hartree-Fock and density functional theory-based nuclear magnetic resonance (NMR) calculation procedure was also performed, and it was used for assigning the 13C and 1H NMR chemical shifts of Carbamazepine.

  19. Molecular structure and spectroscopic characterization of Carbamazepine with experimental techniques and DFT quantum chemical calculations.

    PubMed

    Suhasini, M; Sailatha, E; Gunasekaran, S; Ramkumaar, G R

    2015-04-15

    A systematic vibrational spectroscopic assignment and analysis of Carbamazepine has been carried out by using FT-IR, FT-Raman and UV spectral data. The vibrational analysis were aided by electronic structure calculations - ab initio (RHF) and hybrid density functional methods (B3LYP) performed with standard basis set 6-31G(d,p). Molecular equilibrium geometries, electronic energies, natural bond order analysis, harmonic vibrational frequencies and IR intensities have been computed. A detailed interpretation of the vibrational spectra of the molecule has been made on the basis of the calculated Potential Energy Distribution (PED) by VEDA program. UV-visible spectrum of the compound was also recorded and the electronic properties, such as HOMO and LUMO energies and λmax were determined by HF/6-311++G(d,p) Time-Dependent method. The thermodynamic functions of the title molecule were also performed using the RHF and DFT methods. The restricted Hartree-Fock and density functional theory-based nuclear magnetic resonance (NMR) calculation procedure was also performed, and it was used for assigning the (13)C and (1)H NMR chemical shifts of Carbamazepine.

  20. Structure, spectra and antioxidant action of ascorbic acid studied by density functional theory, Raman spectroscopic and nuclear magnetic resonance techniques

    NASA Astrophysics Data System (ADS)

    Singh, Gurpreet; Mohanty, B. P.; Saini, G. S. S.

    2016-02-01

    Structure, vibrational and nuclear magnetic resonance spectra, and antioxidant action of ascorbic acid towards hydroxyl radicals have been studied computationally and in vitro by ultraviolet-visible, nuclear magnetic resonance and vibrational spectroscopic techniques. Time dependant density functional theory calculations have been employed to specify various electronic transitions in ultraviolet-visible spectra. Observed chemical shifts and vibrational bands in nuclear magnetic resonance and vibrational spectra, respectively have been assigned with the help of calculations. Changes in the structure of ascorbic acid in aqueous phase have been examined computationally and experimentally by recording Raman spectra in aqueous medium. Theoretical calculations of the interaction between ascorbic acid molecule and hydroxyl radical predicted the formation of dehydroascorbic acid as first product, which has been confirmed by comparing its simulated spectra with the corresponding spectra of ascorbic acid in presence of hydrogen peroxide.

  1. Structure, spectra and antioxidant action of ascorbic acid studied by density functional theory, Raman spectroscopic and nuclear magnetic resonance techniques.

    PubMed

    Singh, Gurpreet; Mohanty, B P; Saini, G S S

    2016-02-15

    Structure, vibrational and nuclear magnetic resonance spectra, and antioxidant action of ascorbic acid towards hydroxyl radicals have been studied computationally and in vitro by ultraviolet-visible, nuclear magnetic resonance and vibrational spectroscopic techniques. Time dependant density functional theory calculations have been employed to specify various electronic transitions in ultraviolet-visible spectra. Observed chemical shifts and vibrational bands in nuclear magnetic resonance and vibrational spectra, respectively have been assigned with the help of calculations. Changes in the structure of ascorbic acid in aqueous phase have been examined computationally and experimentally by recording Raman spectra in aqueous medium. Theoretical calculations of the interaction between ascorbic acid molecule and hydroxyl radical predicted the formation of dehydroascorbic acid as first product, which has been confirmed by comparing its simulated spectra with the corresponding spectra of ascorbic acid in presence of hydrogen peroxide.

  2. MRCI+Q calculations on spectroscopic properties of excited states of PbH including spin-orbit coupling

    NASA Astrophysics Data System (ADS)

    Zhao, Shutao; Li, Rui; Zhang, Hua; Li, Huiquan

    2017-03-01

    The 10 Ʌ-S states associated with the lowest four dissociation limits of PbH radical have been studied utilizing configuration interaction method. For better accuracy, the Davidson correction, core-valence correlation and spin-orbit coupling effects are included. The potential energy curves of 10 Ʌ-S states and 18 Ω states have been obtained and characterized. The computed dipole moments of 10 Ʌ-S states are used to reveal the ionic characteristics of the Ʌ-S states. Finally, the transitional dipole moments of several bound Ω states and lifetimes of vibrational states trapped in excited bound Ω states are determined.

  3. Monitoring PDT effects in murine tumors by spectroscopic and imaging techniques

    NASA Astrophysics Data System (ADS)

    Ramaprasad, Subbaraya; Rzepka, Elzbieta; Pi, Jiaxiong; Joshi, Shantaram S.; Dobhal, Mahabeer; Missert, Joseph; Pandey, Ravindra K.

    2004-04-01

    The changes in the tumor that occur following photodynamic therapy (PDT) were studied using a small animal MR imager operating at 7Tesla. The animal model used in these studies was mice bearing radiation induced fibrosarcoma (RIF) tumor on the foot dorsum. The mice were injected with 10μM/kg of one of the photosensitizers: (1) Photofrin, (2) Non-fluorinated porphyrin photosensitizer (DOD-1), (3) Fluorinated porphyrin photosensitizer (DOD-2) and, (4) Fluorinated chlorin photosensitizer (DOD-6). Laser light at 630 or 650 nm (150 mW/cm2, 270 joules/cm2) was delivered to the tumor at 2-24 hours of photosensitizer administration. The MR spectroscopic and imaging examination of the tumors involved both the 1H and 31P nuclei. The tumor bioenergetics was measured by 31P spectroscopy. The water proton relaxivity and diffusion measurements were used to obtain local changes in different regions of the tumor. Changes in 31P MR spectra were observed following PDT using Photofrin and fluorinated chlorin sensitizer (DOD-6). However, no significant changes were observed when the fluorinated porphyrin and its nonfluorinated analog were used. The PDT induced changes in tumor volumes showed significant tumor regression with Photofrin, fluorinated porphyrin and chlorin sensitizers. No tumor regression was observed with the non labeled porphyrin sensitizer and the growth profile followed the general pattern of unperturbed tumors. Serial noninvasive measurements of tumor response to PDT are measurable by both MRI and MRS. The MR derived parameters that are characteristic of the tumor status before and after the therapy are discussed here.

  4. Development of a spectroscopic technique for simultaneous magnetic field, electron density, and temperature measurements in ICF-relevant plasmas

    NASA Astrophysics Data System (ADS)

    Dutra, E. C.; Koch, J. A.; Presura, R.; Angermeier, W. A.; Darling, T.; Haque, S.; Mancini, R. C.; Covington, A. M.

    2016-11-01

    Spectroscopic techniques in the visible range are often used in plasma experiments to measure B-field induced Zeeman splitting, electron densities via Stark broadening, and temperatures from Doppler broadening. However, when electron densities and temperatures are sufficiently high, the broadening of the Stark and Doppler components can dominate the emission spectra and obscure the Zeeman component. In this research, we are developing a time-resolved multi-axial technique for measuring the Zeeman, Stark, and Doppler broadened line emission of dense magnetized plasmas for Z-pinch and Dense Plasma Focus (DPF) accelerators. The line emission is used to calculate the electron densities, temperatures, and B-fields. In parallel, we are developing a line-shape modeling code that incorporates the broadening effects due to Stark, Doppler, and Zeeman effects for dense magnetized plasma. This manuscript presents the details of the experimental setup and line shape code, along with the results obtained from an Al iii doublet at the University of Nevada, Reno at Nevada Terawatt Facility. Future tests are planned to further evaluate the technique and modeling on other material wire array, gas puff, and DPF platforms.

  5. Theoretical calculations on 12 Λ-S and 23 Ω states of CBr+ cation in the gas phase: Potential energy curves, spectroscopic parameters and spin-orbit coupling

    NASA Astrophysics Data System (ADS)

    Shi, Deheng; Niu, Xianghong; Sun, Jinfeng; Zhu, Zunlue

    2014-01-01

    The potential energy curves (PECs) of X1Σ+, a3Π, 13Σ+, 13Δ, 11Δ, 11Σ-, 13Σ-, 11Π, 21Σ+, 23Π, 21Π and 23Σ+ Λ-S states of CBr+ cation and corresponding 23 Ω states are calculated for the first time using the CASSCF method, which is followed by the internally contracted MRCI approach with the aug-cc-pVQZ basis set. All the Λ-S states involved are found to be bound and dissociate into the first dissociation limit of CBr+ cation. Of these Λ-S states, only the 13Σ+ and 13Σ- are inverted ones. The spin-orbit (SO) coupling is accounted for by the state interaction approach with the Breit-Pauli Hamiltonian. Core-valence correlation is included by a cc-pCVTZ basis set. Relativistic correction is calculated with the third-order Douglas-Kroll Hamiltonian approximation at the level of cc-pVQZ basis set. To obtain more reliable results, the PECs obtained by the MRCI calculations are corrected for size-extensivity errors by means of the Davidson modification. The PEC crossings of different Λ-S states are studied. With these PECs, the spectroscopic parameters of all the Λ-S and Ω states involved are obtained by fitting the first ten vibrational levels whenever available, which are calculated by solving the rovibrational Schrödinger equation using the Numerov's method. The spectroscopic parameters are compared with those reported in the literature. Excellent agreement is found between the present results and available measurements. In particular, the energy separation of 352.26 cm-1 between the a3Π0+ and the a3Π1 Ω states agrees well with the measurements of 369±8 cm-1, and the ωe results of 907.45 and 907.08 cm-1 for the a3Π0+ and a3Π1 Ω states are in excellent agreement with the measurements of 906±2 and 903±6 cm-1, respectively. These show that the spectroscopic parameters obtained in the present paper can be expected to be reliable predicted ones.

  6. Advanced techniques for high resolution spectroscopic observations of cosmic gamma-ray sources

    NASA Technical Reports Server (NTRS)

    Matteson, J. L.; Pelling, M. R.; Peterson, L. E.; Lin, R. P.; Anderson, K. A.; Pehl, R. H.; Hurley, K. C.; Vedrenne, G.; Sniel, M.; Durouchoux, P.

    1985-01-01

    An advanced gamma-ray spectrometer that is currently in development is described. It will obtain a sensitivity of 0.0001 ph/sq cm./sec in a 6 hour balloon observation and uses innovative techniques for background reduction and source imaging.

  7. Spatially-resolved spectroscopic technique for measuring optical properties of food

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Quantification of optical properties is important to understand light interaction with biological materials, and to develop effective optical sensing techniques for property characterization and quality measurement of food products. This chapter reviews spatially-resolved method, with the focus on f...

  8. Reflective and photoacoustic infrared spectroscopic techniques in assessment of binding media in paintings

    NASA Astrophysics Data System (ADS)

    Łojewski, Tomasz; Bagniuk, Jacek; Kołodziej, Andrzej; Łojewska, Joanna

    2011-11-01

    This study proposes a method to estimate the lipid content in binding media in paintings that can be used at any laboratory equipped with an infrared spectrometer. The lipid content estimator, termed greasiness index (GI), is defined as a ratio of lipid ν(C=O) and protein amide I bands at 1743 and 1635 cm-1, respectively. Three Fourier transform infrared (FTIR) sampling techniques were evaluated for GI determination: reflective attenuated total reflection—ATR, specular reflection microscopy— μSR and photoacoustic—PAS. A set of model painting samples containing three tempera binding media (casein, egg, egg + oil), seven pigments and one varnish type were used in the study. Multivariate analysis was used to evaluate the resulting data. A good reproducibility of GI was obtained by ATR and PAS but not with μSR. The discriminative power of the technique is higher for unvarnished samples, but, generally, the GI estimator can be used for the categorisation of binding media in large populations of painting samples analysed with the same FTIR technique (sampling technique, detection, etc.).

  9. Mapping of cerebral perfusion territories using territorial arterial spin labeling: techniques and clinical application.

    PubMed

    Hartkamp, Nolan S; Petersen, Esben T; De Vis, Jill B; Bokkers, Reinoud P H; Hendrikse, Jeroen

    2013-08-01

    A knowledge of the exact cerebral perfusion territory which is supplied by any artery is of great importance in the understanding and diagnosis of cerebrovascular disease. The development and optimization of territorial arterial spin labeling (T-ASL) MRI techniques in the past two decades have made it possible to visualize and determine the cerebral perfusion territories in individual patients and, more importantly, to do so without contrast agents or otherwise invasive procedures. This review provides an overview of the development of ASL techniques that aim to visualize the general cerebral perfusion territories or the territory of a specific artery of interest. The first efforts of T-ASL with pulsed, continuous and pseudo-continuous techniques are summarized and subsequent clinical studies using T-ASL are highlighted. In the healthy population, the perfusion territories of the brain-feeding arteries are highly variable. This high variability requires special consideration in specific patient groups, such as patients with cerebrovascular disease, stroke, steno-occlusive disease of the large arteries and arteriovenous malformations. In the past, catheter angiography with selective contrast injection was the only available method to visualize the cerebral perfusion territories in vivo. Several T-ASL methods, sometimes referred to as regional perfusion imaging, are now available that can easily be combined with conventional brain MRI examinations to show the relationship between the cerebral perfusion territories, vascular anatomy and brain infarcts or other pathology. Increased availability of T-ASL techniques on clinical MRI scanners will allow radiologists and other clinicians to gain further knowledge of the relationship between vasculature and patient diagnosis and prognosis. Treatment decisions, such as surgical revascularization, may, in the near future, be guided by information provided by T-ASL MRI in close correlation with structural MRI and quantitative

  10. Artificial tektites: an experimental technique for capturing the shapes of spinning drops

    NASA Astrophysics Data System (ADS)

    Baldwin, K. A.

    2014-12-01

    Tektites are small stones formed from rapidly cooling drops of molten rock ejected from high velocity asteroid impacts with the Earth, that freeze into a myriad of shapes during flight. Many splash-form tektites have an elongated or dumb-bell shape owing to their rotation prior to solidification[1]. Here we present a novel method for creating 'artificial tektites' from spinning drops of molten wax, using diamagnetic levitation to suspend the drops[2]. We find that the solid wax models produced this way are the stable equilibrium shapes of a spinning liquid droplet held together by surface tension. In addition to the geophysical interest in tektite formation, the stable equilibrium shapes of liquid drops have implications for many physical phenomena, covering a wide range of length scales, from nuclear physics (e.g. in studies of rapidly rotating atomic nuclei), to astrophysics (e.g. in studies of the shapes of astronomical bodies such as asteroids, rapidly rotating stars and event horizons of rotating black holes). For liquid drops bound by surface tension, analytical and numerical methods predict a series of stable equilibrium shapes with increasing angular momentum. Slowly spinning drops have an oblate-like shape. With increasing angular momentum these shapes become secularly unstable to a series of triaxial pseudo-ellipsoids that then evolve into a family of two-lobed 'dumb-bell' shapes as the angular momentum is increased still further. Our experimental method allows accurate measurements of the drops to be taken, which are useful to validate numerical models. This method has provided a means for observing tektite formation, and has additionally confirmed experimentally the stable equilibrium shapes of liquid drops, distinct from the equivalent shapes of rotating astronomical bodies. Potentially, this technique could be applied to observe the non-equilibrium dynamic processes that are also important in real tektite formation, involving, e.g. viscoelastic

  11. Spectroscopic capture and reactivity of a low-spin cobalt(IV)-oxo complex stabilized by binding redox-inactive metal ions.

    PubMed

    Hong, Seungwoo; Pfaff, Florian F; Kwon, Eunji; Wang, Yong; Seo, Mi-Sook; Bill, Eckhard; Ray, Kallol; Nam, Wonwoo

    2014-09-22

    High-valent cobalt-oxo intermediates are proposed as reactive intermediates in a number of cobalt-complex-mediated oxidation reactions. Herein we report the spectroscopic capture of low-spin (S=1/2) Co(IV)-oxo species in the presence of redox-inactive metal ions, such as Sc(3+), Ce(3+), Y(3+), and Zn(2+), and the investigation of their reactivity in C-H bond activation and sulfoxidation reactions. Theoretical calculations predict that the binding of Lewis acidic metal ions to the cobalt-oxo core increases the electrophilicity of the oxygen atom, resulting in the redox tautomerism of a highly unstable [(TAML)Co(III)(O˙)](2-) species to a more stable [(TAML)Co(IV)(O)(M(n+))] core. The present report supports the proposed role of the redox-inactive metal ions in facilitating the formation of high-valent metal-oxo cores as a necessary step for oxygen evolution in chemistry and biology.

  12. New spectroscopic tools and techniques for characterizing M dwarfs and discovering their planets in the near-infrared

    NASA Astrophysics Data System (ADS)

    Terrien, Ryan C.

    M dwarfs are the least massive and most common stars in the Galaxy. Due to their prevalence and long lifetimes, these diminutive stars play an outsize role in several fields of astronomical study. In particular, it is now known that they commonly host planetary systems, and may be the most common hosts of Earth-size, rocky planets in the habitable zone. A comprehensive understanding of M dwarfs is crucial for understanding the origins and conditions of their planetary systems, including their potential habitability. Such an understanding depends on methods for precisely and accurately measuring their properties. These tools have broader applicability as well, underlying the use of M dwarfs as fossils of Galactic evolution, and helping to constrain the structures and interiors of these stars. The measurement of the fundamental parameters of M dwarfs is encumbered by their spectral complexity. Unlike stars of spectral type F, G, or K that are similar to our G type Sun, whose spectra are dominated by continuum emission and atomic features, the cool atmospheres of M dwarfs are dominated by complex molecular absorption. Another challenge for studies of M dwarfs is that these stars are optically faint, emitting much of their radiation in the near-infrared (NIR). The availability and performance of NIR spectrographs have lagged behind those of optical spectrographs due to the challenges of producing low-noise, high-sensitivity NIR detector arrays, which have only recently become available. This thesis discusses two related lines of work that address these challenges, motivated by the development of the Habitable Zone Planet Finder (HPF), a NIR radial velocity (RV) spectrograph under development at Penn State that will search for and confirm planets around nearby M dwarfs. This work includes the development and application of new NIR spectroscopic techniques for characterizing M dwarfs, and the development and optimization of new NIR instrumentation for HPF. The first line

  13. Murillo's paintings revealed by spectroscopic techniques and dedicated laboratory-made micro X-ray diffraction.

    PubMed

    Duran, A; Siguenza, M B; Franquelo, M L; Jimenez de Haro, M C; Justo, A; Perez-Rodriguez, J L

    2010-06-25

    This paper describes one of the first case studies using micro-diffraction laboratory-made systems to analyse painting cross-sections. Pigments, such as lead white, vermilion, red ochre, red lac, lapis lazuli, smalt, lead tin yellow type I, massicot, ivory black, lamp black and malachite, were detected in cross-sections prepared from six Bartolomé Esteban Murillo paintings by micro-Raman and micro-XRD combined with complementary techniques (optical microscopy, SEM-EDS, and FT-IR). The use of micro-XRD was necessary due to the poor results obtained with conventional XRD. In some cases, pigment identification was only possible by combining results from the different analytical techniques utilised in this study.

  14. Neutron Stimulated Emission Computed Tomography: A New Technique for Spectroscopic Medical Imaging

    NASA Astrophysics Data System (ADS)

    Kapadia, A. J.

    Neutron stimulated emission computed tomography (NSECT) is being developed as a new medical-imaging technique to quantify spatial distributions of elements in a sample through inelastic scattering of fast neutrons and detection of the resulting gamma rays. It has the potential to diagnose several disorders in the human body that are characterized by changes in element concentration in the diseased tissue. NSECT is sensitive to several naturally occurring elements in the human body that demonstrate concentration changes in the presence of diseases. NSECT, therefore, has the potential to noninvasively diagnose such disorders with radiation dose that is comparable to other ionizing imaging modalities. This chapter discusses the development and progress of NSECT and presents an overview of the current status of the imaging technique.

  15. Microsampling techniques for infrared spectroscopic analysis of lunar and terrestrial minerals

    NASA Technical Reports Server (NTRS)

    Estep, P. A.; Kovach, J. J.; Karr, C.

    1973-01-01

    Microsampling techniques have been developed for infrared analysis of single mineral grains from lunar rocks and dusts, allowing a detailed molecular structure characterization of these complex fine-grained samples. The methods include special devices for isolating single grains, preparing micropellets from the grains, and obtaining in situ microspecular reflectance spectra from grains in polished rock samples. Although specifically developed for the work on lunar samples, the special techniques for single grain infrared analysis were found to be equally useful in studies of complex terrestrial mineral samples. For example, infrared microanalysis has contributed substantially in solving problems concerned with our natural resources, such as the structural characterization of minerals from commercial iron ores, marine deposits, coal, and fly ash derived from coal.

  16. Innovative combination of spectroscopic techniques to reveal nanoparticle fate in a crop plant

    NASA Astrophysics Data System (ADS)

    Larue, Camille; Castillo-Michel, Hiram; Stein, Ricardo J.; Fayard, Barbara; Pouyet, Emeline; Villanova, Julie; Magnin, Valérie; Pradas del Real, Ana-Elena; Trcera, Nicolas; Legros, Samuel; Sorieul, Stéphanie; Sarret, Géraldine

    2016-05-01

    Nanotechnology is the new industrial revolution of our century. Its development leads to an increasing use of nanoparticles and thus to their dissemination. Their fate in the environment is of great concern and especially their possible transfer in trophic chains might be an issue for food safety. However, so far our knowledge on this topic has been restricted by the lack of appropriate techniques to characterize their behavior in complex matrices. Here, we present in detail the use of cutting-edge beam-based techniques for nanoparticle in situ localization, quantification and speciation in a crop plant species (Lactuca sativa). Lettuce seedlings have been exposed to TiO2 and Ag nanoparticles and analyzed by inductively coupled plasma spectrometry, micro-particle induced X-ray emission coupled to Rutherford backscattering spectroscopy on nuclear microprobe, micro-X-ray fluorescence spectroscopy and X-ray absorption near edge structure spectroscopy. The benefits and drawbacks of each technique are discussed, and the types of information that can be drawn, for example on the translocation to edible parts, change of speciation within the plant, detoxification mechanisms, or impact on the plant ionome, are highlighted. Such type of coupled approach would be an asset for nanoparticle risk assessment.

  17. Development of a spectroscopic technique for simultaneous magnetic field, electron density, and temperature measurements in Z-pinch plasmas

    NASA Astrophysics Data System (ADS)

    Dutra, Eric; Presura, Radu; Covington, Aaron; Mancini, Roberto; Darling, Timothy; Angermeier, William

    2016-10-01

    Visible spectroscopic techniques are often used in plasma experiments to measure B-field induced Zeeman splitting, electron densities via Stark broadening, and temperatures from Doppler broadening. However, when electron densities and temperatures are sufficiently high, the broadening of the Stark and Doppler components can dominate the emission spectra and obscure the Zeeman component. In this research, we are developing a time-resolved multi-axial technique for measuring the Zeeman, Stark, and Doppler broadened line emission of dense magnetized plasmas for Z-pinch. In parallel, we are developing a line-shape modeling code that incorporates the broadening effects due to Stark, Doppler, and Zeeman effects for dense magnetized plasma. Experiments were conducted at the University of Nevada (Reno) at the Nevada Terawatt Facility (NTF) using the 1 MA Z-pinch (Zebra). The research explored the optical emission of Al III doublet, 4P 2P3/2 to 4S 2S1/2 and 4P 2P1/2 to 4s 2S1/2 transitions and used it to measure Zeeman, Stark, and Doppler broadened emission. The initial parameters for the line shape code are varied to simulate emission spectra. The simulated spectra are compared to experimental results. These results are used to infer temperature, electron density, and B-fields in the magnetized plasma.

  18. Chemical and morphological changes in hydrochars derived from microcrystalline cellulose and investigated by chromatographic, spectroscopic and adsorption techniques.

    PubMed

    Diakité, Mamadou; Paul, Andrea; Jäger, Christian; Pielert, Judith; Mumme, Jan

    2013-12-01

    Hydrothermal carbonization (HTC) can be used for converting the biomass into a carbon-rich material, whose application as a fuel requires higher heating value, whereas soil amendment needs stable carbon. This work was focused on the characterization of hydrochars derived from microcrystalline cellulose. The chars were investigated using elemental analysis, Brunauer-Emmett-Teller technique, nuclear magnetic resonance spectroscopy, Raman, Fourier transform infrared, and electron spin resonance spectroscopy. Severity in temperature between 230 and 270°C with reaction times between 2 and 10 h only affect the carbon content moderately. The results show that aromatization of HTC chars correlates well with temperature, which was further supported by the increase of organic radicals with decreasing g values at higher temperatures. Based on these results, the energetic use of chars favors mild HTC (T<230°C and t≤6 h), while the soil amendement favors serve conditions (T≥230°C, and t>6 h).

  19. Development and applications of laser spectroscopic techniques related to combustion diagnostics

    NASA Astrophysics Data System (ADS)

    Aldén, Marcus

    2006-07-01

    Thanks to features as non-intrusiveness combined with high spatial and temporal resolution, various laser diagnostic techniques have during the last decades become of utmost importance for characterization of combustion related phenomena. In the following presentation some further development of the techniques will be highlighted aiming at a) surface temperatures using Thermographic Phosphors, TP, b) species specific, spatially and temporally resolved detection of species absorbing in the IR spectral region using polarization spectroscopy and Laser-induced fluorescence, and finally c) high speed visualization using a special designed laser system in combination with a framing camera. In terms of surface thermometry, Thermographic Phosphors have been used for many years for temperature measurements on solid surfaces. We have during the last years further developed and applied this technique for temperature measurements on burning surfaces and on materials going through phase shifts, e.g. pyrolysis and droplets. The basic principle behind this technique is to apply micron size particles to the surface of interest. By exciting the TP with a short pulse UV laser (ns), the phosphorescence will exhibit a behaviour where the spectral emission as well as the temporal decay are dependent on the temperature. It is thus possible to measure the temperature both in one and two dimensions. The presentation will include basic description of the technique as well as various applications, e.g in fire science, IC engines and gasturbines. Several of the species of interest for combustion/flow diagnostics exhibit a molecular structure which inhibits the use of conventional laser-induced fluorescence for spatially and spectrally resolved measurements. We have during the last years investigated the use of excitation and detection in the infrared region of the spectrum. Here, it is possible to detect both carbonmono/dioxide, water as well as species specific hydrocarbons. The techniques

  20. The analytical investigations of ancient pottery from Kaveripakkam, Vellore dist, Tamilnadu by spectroscopic techniques.

    PubMed

    Ravisankar, R; Naseerutheen, A; Annamalai, G Raja; Chandrasekaran, A; Rajalakshmi, A; Kanagasabapathy, K V; Prasad, M V R; Satpathy, K K

    2014-01-01

    Analytical investigations using Fourier Transform infrared spectroscopy (FT-IR), Powder X-ray Diffraction (PXRD), Thermal Analysis (TG-DTA), Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Fluorescence Spectrometry (EDXRF) were carried out on ancient pottery fragments from Kaveripakkam, in order to outline manufacturing skills, technology information, firing condition and temperature of potteries. The whole set of data showed the firing temperature in the range of 800-900°C. The analytical characterization of the potsherds, by different complimentary techniques has allowed to identifying the raw materials and technology applied by the ancient artisans.

  1. The analytical investigations of ancient pottery from Kaveripakkam, Vellore dist, Tamilnadu by spectroscopic techniques

    NASA Astrophysics Data System (ADS)

    Ravisankar, R.; Naseerutheen, A.; Raja Annamalai, G.; Chandrasekaran, A.; Rajalakshmi, A.; Kanagasabapathy, K. V.; Prasad, M. V. R.; Satpathy, K. K.

    2014-03-01

    Analytical investigations using Fourier Transform infrared spectroscopy (FT-IR), Powder X-ray Diffraction (PXRD), Thermal Analysis (TG-DTA), Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Fluorescence Spectrometry (EDXRF) were carried out on ancient pottery fragments from Kaveripakkam, in order to outline manufacturing skills, technology information, firing condition and temperature of potteries. The whole set of data showed the firing temperature in the range of 800-900 °C. The analytical characterization of the potsherds, by different complimentary techniques has allowed to identifying the raw materials and technology applied by the ancient artisans.

  2. Micro-spectroscopic techniques applied to characterization of varnished archeological findings

    NASA Astrophysics Data System (ADS)

    Barone, G.; Ioppolo, S.; Majolino, D.; Migliardo, P.; Ponterio, R.

    2000-04-01

    This work reports an analysis on terracotta varnished finding recovered in east Sicily area (Messina). We have performed FTIR micro-spectroscopy and electronic microscopy (SEM)measurements in order to recognize the elemental constituents of the varnished surfaces. Furthermore, for all the samples, a study on the bulk has been performed by Fourier Transform Infrared Absorption. The analyzed samples consist of a number of pottery fragments belonging to archaic and classical ages, varnished in black and red colors. The obtained data furnished useful information about composition of decorated surfaces and bulk matrixes, about baking temperature, manufacture techniques and alteration mechanisms of findings due to the long burial.

  3. Raman spectroscopic studies of thin film carbon nanostructures deposited using electro deposition technique

    NASA Astrophysics Data System (ADS)

    Dayal, Saurabh; Sasi, Arshali; Jhariya, Sapna; Sasikumar, C.

    2016-05-01

    In the present work our focus is to synthesize carbon nanostructures (CNS) by electro deposition technique without using any surface pretreatment or catalyst preparation before CNS formation. The process were carried out at significantly low voltage and at low temperature as reported elsewhere. Further the samples were characterized using different characterization tools such as SEM and Raman spectroscopy. The SEM results showed the fibres or tubular like morphology. Raman spectra shows strong finger print at 1600 cm-1 (G peak), 1350 cm-1 (D peak) along with the radial breathing mode (RBM) between 150cm-1 to 300 cm-1. This confirms the formation of tubular carbon nanostructures.

  4. Study on the interaction of silver(I) complex with bovine serum albumin by spectroscopic techniques.

    PubMed

    Shahabadi, Nahid; Maghsudi, Maryam; Ahmadipour, Zeinab

    2012-06-15

    The interaction of silver(I) complex, [Ag (2,9-dimethyl-1,10-phenanthroline)(2)](NO(3))·H(2)O, and bovine serum albumin (BSA) was investigated by spectrophotometry, spectrofluorimetry and circular dichroism (CD) techniques. The experimental results indicated that the quenching mechanism of BSA by the complex was a static procedure. Various binding parameters were evaluated. The negative value of ΔH, negative value of ΔS and the negative value of ΔG indicated that van der Waals force and hydrogen bonding play major roles in the binding of the complex and BSA. Based on Forster's theory of non-radiation energy transfer, the binding distance, r, between the donor (BSA) and acceptor (Ag(I) complex) was evaluated. The results of CD and UV-vis spectroscopy showed that the binding of this complex could bind to BSA and be effectively transported and eliminated in the body.

  5. Analysis of the binding interaction in uric acid - Human hemoglobin system by spectroscopic techniques.

    PubMed

    Makarska-Bialokoz, Magdalena

    2017-01-31

    The binding interaction between human hemoglobin and uric acid has been studied for the first time, by UV-vis absorption and steady-state, synchronous and three-dimensional fluorescence techniques. Characteristic effects observed for human hemoglobin intrinsic fluorescence during interaction with uric acid at neutral pH point at the formation of stacking non-covalent and non-fluorescent complexes. All the calculated parameters, the binding, fluorescence quenching and bimolecular quenching rate constants, as well as Förster resonance energy transfer parameters confirm the existence of static quenching. The results of synchronous fluorescence measurements indicate that the fluorescence quenching of human hemoglobin originates both from Trp and Tyr residues and that the addition of uric acid could significantly hinder the physiological functions of human hemoglobin.

  6. Comparison of spectroscopic techniques for the determination of Kjeldahl and ammoniacal nitrogen content of farmyard manure.

    PubMed

    Kemsley, E K; Tapp, H S; Scarlett, A J; Miles, S J; Hammond, R; Wilson, R H

    2001-02-01

    The feasibility of determining the nitrogen content of farmyard manure using infrared spectroscopy was investigated. Fifteen samples each of cattle, pig, and turkey manure were analyzed by three infrared techniques: Fourier transform mid-infrared (MIR), using attenuated total reflection (ATR); near-infrared reflectance (NIR-R); and near-infrared optothermal photoacoustic (NIR-OT). The near-infrared measurements were made at wavelengths determined respectively by four (NIR-OT) and five (NIR-R) band-pass filters. The total nitrogen (using the Kjeldahl method) and volatile (ammoniacal) nitrogen contents of all samples were measured by wet chemistry. Internally cross-validated (ICV) partial least-squares (PLS) regression was then used to obtain calibrations for the nitrogen content. The data sets obtained by each technique were treated separately. Within these sets, data from each manure type were treated both separately and combined: the best predictive ability was obtained by combining data from all three manure types. From the combined data set, the residual standard deviations and correlation coefficients for the ICV-predicted versus actual Kjeldahl nitrogen content were, respectively, 6772 mg/kg dry wt, 0.862 (MIR); 9434 mg/kg dry wt, 0.771 (NIR-OT); and 8943 mg/kg dry wt, 0.865 (NIR-R). For the ammoniacal nitrogen content, the residual standard deviations and correlation coefficients were 3869 mg/kg dry wt, 0.899 (MIR); 6079 mg/kg dry wt, 0.820 (NIR-OT); and 3498 mg/kg dry wt, 0.961 (NIR-R).

  7. MOS solar cells with oxides deposited by sol-gel spin-coating techniques

    SciTech Connect

    Huang, Chia-Hong; Chang, Chung-Cheng; Tsai, Jung-Hui

    2013-06-15

    The metal-oxide-semiconductor (MOS) solar cells with sol-gel derived silicon dioxides (SiO{sub 2}) deposited by spin coating are proposed in this study. The sol-gel derived SiO{sub 2} layer is prepared at low temperature of 450 Degree-Sign C. Such processes are simple and low-cost. These techniques are, therefore, useful for largescale and large-amount manufacturing in MOS solar cells. It is observed that the short-circuit current (I{sub sc}) of 2.48 mA, the open-circuit voltage (V{sub os}) of 0.44 V, the fill factor (FF) of 0.46 and the conversion efficiency ({eta}%) of 2.01% were obtained by means of the current-voltage (I-V) measurements under AM 1.5 (100 mW/cm{sup 2}) irradiance at 25 Degree-Sign C in the MOS solar cell with sol-gel derived SiO{sub 2}.

  8. Characterizations of multilayer ZnO thin films deposited by sol-gel spin coating technique

    NASA Astrophysics Data System (ADS)

    Khan, M. I.; Bhatti, K. A.; Qindeel, Rabia; Alonizan, Norah; Althobaiti, Hayat Saeed

    In this work, zinc oxide (ZnO) multilayer thin films are deposited on glass substrate using sol-gel spin coating technique and the effect of these multilayer films on optical, electrical and structural properties are investigated. It is observed that these multilayer films have great impact on the properties of ZnO. X-ray Diffraction (XRD) confirms that ZnO has hexagonal wurtzite structure. Scanning Electron Microscopy (SEM) showed the crack-free films which have uniformly distributed grains structures. Both micro and nano particles of ZnO are present on thin films. Four point probe measured the electrical properties showed the decreasing trend between the average resistivity and the number of layers. The optical absorption spectra measured using UV-Vis. showed the average transmittance in the visible region of all films is 80% which is good for solar spectra. The performance of the multilayer as transparent conducting material is better than the single layer of ZnO. This work provides a low cost, environment friendly and well abandoned material for solar cells applications.

  9. Rapid non-destructive assessment of pork edible quality by using VIS/NIR spectroscopic technique

    NASA Astrophysics Data System (ADS)

    Zhang, Leilei; Peng, Yankun; Dhakal, Sagar; Song, Yulin; Zhao, Juan; Zhao, Songwei

    2013-05-01

    The objectives of this research were to develop a rapid non-destructive method to evaluate the edible quality of chilled pork. A total of 42 samples were packed in seal plastic bags and stored at 4°C for 1 to 21 days. Reflectance spectra were collected from visible/near-infrared spectroscopy system in the range of 400nm to 1100nm. Microbiological, physicochemical and organoleptic characteristics such as the total viable counts (TVC), total volatile basic-nitrogen (TVB-N), pH value and color parameters L* were determined to appraise pork edible quality. Savitzky-Golay (SG) based on five and eleven smoothing points, Multiple Scattering Correlation (MSC) and first derivative pre-processing methods were employed to eliminate the spectra noise. The support vector machines (SVM) and partial least square regression (PLSR) were applied to establish prediction models using the de-noised spectra. A linear correlation was developed between the VIS/NIR spectroscopy and parameters such as TVC, TVB-N, pH and color parameter L* indexes, which could gain prediction results with Rv of 0.931, 0.844, 0.805 and 0.852, respectively. The results demonstrated that VIS/NIR spectroscopy technique combined with SVM possesses a powerful assessment capability. It can provide a potential tool for detecting pork edible quality rapidly and non-destructively.

  10. The Book of Kells: A non-invasive MOLAB investigation by complementary spectroscopic techniques

    NASA Astrophysics Data System (ADS)

    Doherty, B.; Daveri, A.; Clementi, C.; Romani, A.; Bioletti, S.; Brunetti, B.; Sgamellotti, A.; Miliani, C.

    2013-11-01

    This paper highlights the efficacy of non-invasive portable spectroscopy for assessing the execution technique and constituent materials in one of the most important medieval manuscripts, the Book of Kells. An aimed campaign of in situ measurements by the MObile LABoratory (MOLAB) has analyzed its elemental composition and vibrational and electronic molecular properties. The ample analytical toolbox has afforded complementary diagnostic information of the pigment palette permitting the characterization of both inorganic and organic materials as pigments and dyes in the white, purple, blue, red, orange, green and black areas. In particular, the novel widespread use of calcinated gypsum (anhydrite) as both a white pigment and in correlation to the organic dyes in this manuscript has been noted. The non-invasive identification of the organic dye orchil is significant considering its rare non invasive detection in medieval manuscripts. Finally the occurrence of particular alterations of the organic black areas giving rise to calcium carboxylate and calcium oxalate has been specifically highlighted. Importantly, this work elaborates complex aspects of the employed painting materials which have given rise to numerous significant points of interest for a more elaborate understanding of this Irish treasure.

  11. The Book of Kells: a non-invasive MOLAB investigation by complementary spectroscopic techniques.

    PubMed

    Doherty, B; Daveri, A; Clementi, C; Romani, A; Bioletti, S; Brunetti, B; Sgamellotti, A; Miliani, C

    2013-11-01

    This paper highlights the efficacy of non-invasive portable spectroscopy for assessing the execution technique and constituent materials in one of the most important medieval manuscripts, the Book of Kells. An aimed campaign of in situ measurements by the MObile LABoratory (MOLAB) has analyzed its elemental composition and vibrational and electronic molecular properties. The ample analytical toolbox has afforded complementary diagnostic information of the pigment palette permitting the characterization of both inorganic and organic materials as pigments and dyes in the white, purple, blue, red, orange, green and black areas. In particular, the novel widespread use of calcinated gypsum (anhydrite) as both a white pigment and in correlation to the organic dyes in this manuscript has been noted. The non-invasive identification of the organic dye orchil is significant considering its rare non invasive detection in medieval manuscripts. Finally the occurrence of particular alterations of the organic black areas giving rise to calcium carboxylate and calcium oxalate has been specifically highlighted. Importantly, this work elaborates complex aspects of the employed painting materials which have given rise to numerous significant points of interest for a more elaborate understanding of this Irish treasure.

  12. Notes on the p-spin glass studied via Hamilton-Jacobi and smooth-cavity techniques

    NASA Astrophysics Data System (ADS)

    Agliari, Elena; Barra, Adriano; Burioni, Raffaella; Di Biasio, Aldo

    2012-06-01

    In these notes, we continue our investigation of classical toy models of disordered statistical mechanics, through techniques recently developed and tested mainly on the paradigmatic Sherrington-Kirkpatrick spin glass. Here, we consider the p-spin-glass model with Ising spins and interactions drawn from a normal distribution N[0,1]. After a general presentation of its properties (e.g., self-averaging of the free energy, existence of a suitable thermodynamic limit), we study its equilibrium behavior within the Hamilton-Jacobi framework and the smooth cavity approach. Through the former we find both the RS and the 1-RSB expressions for the free-energy, coupled with their self-consistent relations for the overlaps. Through the latter, we recover these results as irreducible expression, and we study the generalization of the overlap polynomial identities suitable for this model; a discussion on their deep connection with the structure of the internal energy and the entropy closes the investigation.

  13. Surface analysis of all elements with isotopic resolution at high ambient pressures using ion spectroscopic techniques

    SciTech Connect

    Smentkowski, V.S.; Krauss, A.R.; Gruen, D.M.; Holecek, J.C.; Schultz, J.A.

    1997-09-01

    The authors have developed a mass spectrometer capable of surface analysis using the techniques of secondary ion mass spectroscopy (SIMS) and mass spectroscopy of recoiled ions (MSRI). For SIMS, an energetic ion beam creates a collision cascade which results in the ejection of low kinetic energy secondary ions from the surface being analyzed. The low kinetic energy SIMS ions are very susceptible to charge neutralization with the surface, and as a result, the SIMS ion yield varies by orders of magnitude depending on the chemical state of the surface. SIM spectra contain elemental ions, and molecular ions. For MSRI, a pulsed ion beam induces a binary collision with the surface being analyzed and the surface species are recoiled into the forward scattering direction with a large kinetic energy. The violence of the binary collision results in complete molecular decomposition, and only elemental ions are detected. The high kinetic energy MSRI ions are much less susceptible to charge neutralization with the surface than the low kinetic energy SIMS ions. In MSRI, the ion yield typically varies by less than a factor of ten as the chemical state of the surface changes--simplifying quantitative analysis vs. SIMS. In this paper, they authors will demonstrate that the high kinetic energy MSRI ions are able to transverse high pressure paths with only a reduction in peak intensity--making MSRI an ideal tool for real-time, in-situ film growth studies. The use of a single analyzer for both MSRI and SIMS is unique and provides complimentary information.

  14. Measurement of the optical properties of skin using terahertz time-domain spectroscopic techniques

    NASA Astrophysics Data System (ADS)

    Wilmink, Gerald J.; Ibey, Bennett L.; Tongue, Thomas; Schulkin, Brian; Peralta, Xomalin; Rivest, Benjamin D.; Haywood, Eric C.; Roach, William P.

    2010-02-01

    Terahertz (THz) radiation is increasingly being used in biomedical imaging and spectroscopy applications. These techniques show tremendous promise to provide new sophisticated tools for the improved detection of skin cancer. However, despite recent efforts to develop these applications, few studies have been conducted to characterize the optical properties of skin at THz frequencies. Such information is required to better understand THz-tissue interactions, and is critical for determining the feasibility of proposed applications. In this study, we have developed and tested a THz time-domain spectroscopy system. We used this system to acquire the optical properties for fresh and frozen/thawed excised porcine skin from 0.1 to 2.0 THz. Results show that the index of refraction (n) for both frozen and fresh skin decreases with frequency. For frozen skin, n equals 2.5 at 0.1 THz and 2.0 at 2.0 THz, and for fresh skin equals 2.0 at 0.1 THz and 1.7 at 2.0 THz. Values for the absorption coefficient (μa) increase with frequency for both frozen and fresh skin. Frozen skin exhibits μa values equal to 56 cm-1 at 0.1 THz and 550 cm-1 at 2.0 THz, whereas fresh skin exhibits values of 56 cm-1 at 0.1 THz and 300 cm-1 at 2.0 THz. Assuming the optical penetration depth (δ) is inversely proportional to μa (absorption-dominated interactions), THz radiation has limited δ in skin (200 μm at 0.1 THz to 40 μm at 2.0 THz). These results suggest that applications exploiting THz radiation show the most promise for investigating superficial tissues.

  15. Study on the interaction between histidine-capped Au nanoclusters and bovine serum albumin with spectroscopic techniques

    NASA Astrophysics Data System (ADS)

    Zheng, Chengzhi; Wang, Huiping; Xu, Wei; Xu, Chaoyong; Liang, Jiangong; Han, Heyou

    2014-01-01

    The understanding of the protein-nanoclusters interaction has significant implications for biological applications of nanoclusters (NCs). In this manuscript, the interaction of histidine-capped Au nanoclusters (NCs) with bovine serum albumin (BSA) has been investigated by fluorescence, UV-vis, circular dichroism (CD) and Raman spectroscopic techniques under simulative physiological conditions. The results showed that the fluorescence of BSA was quenched by Au NCs. The quenching mechanism was discussed to be a dynamic quenching style, which was proved by the fluorescence spectra and UV-vis absorption spectra. According to modified Stern-Volmer equations at different temperatures, corresponding thermodynamic parameters, ΔHθ, ΔSθ and ΔGθ were observed to be 35.97 kJ mol-1, 199.53 J mol-1 K-1 and -23.49 kJ mol-1, respectively. The hydrophobic force played a key role in the interaction process. Further results from the CD spectra and Raman spectra demonstrated that the α-helical content in BSA was reduced upon interaction with Au NCs which induced a partial protein destabilization. This study contributes to a better understanding of the biology toxicity of Au NCs to biomolecular, which is very essential for the development of safe and functional Au NCs.

  16. Binding of caffeine with caffeic acid and chlorogenic acid using fluorescence quenching, UV/vis and FTIR spectroscopic techniques.

    PubMed

    Belay, Abebe; Kim, Hyung Kook; Hwang, Yoon-Hwae

    2016-03-01

    The interactions of caffeine (CF) with chlorogenic acid (CGA) and caffeic acid (CFA) were investigated by fluorescence quenching, UV/vis and Fourier transform infrared (FTIR) spectroscopic techniques. The results of the study indicated that the fluorescence quenching between caffeine and hydroxycinnamic acids could be rationalized in terms of static quenching or the formation of non-fluorescent CF-CFA and CF-CGA complexes. From fluorescence quenching spectral analysis, the quenching constant (KSV), quenching rate constant (kq), number of binding sites (n), thermodynamic properties and conformational changes of the interaction were determined. The quenching constants (KSV) between CF and CGA, CFA are 1.84 × 10(4) and 1.04 × 10(4) L/mol at 298 K and their binding site n is ~ 1. Thermodynamic parameters determined using the Van't Hoff equation indicated that hydrogen bonds and van der Waal's forces have a major role in the reaction of caffeine with caffeic acid and chlorogenic acid. The 3D fluorescence, UV/vis and FTIR spectra also showed that the binding of CF with CFA and CGA induces conformational changes in CFA and CGA.

  17. Development and experimental testing of an optical micro-spectroscopic technique incorporating true line-scan excitation.

    PubMed

    Biener, Gabriel; Stoneman, Michael R; Acbas, Gheorghe; Holz, Jessica D; Orlova, Marianna; Komarova, Liudmila; Kuchin, Sergei; Raicu, Valerică

    2013-12-27

    Multiphoton micro-spectroscopy, employing diffraction optics and electron-multiplying CCD (EMCCD) cameras, is a suitable method for determining protein complex stoichiometry, quaternary structure, and spatial distribution in living cells using Förster resonance energy transfer (FRET) imaging. The method provides highly resolved spectra of molecules or molecular complexes at each image pixel, and it does so on a timescale shorter than that of molecular diffusion, which scrambles the spectral information. Acquisition of an entire spectrally resolved image, however, is slower than that of broad-bandwidth microscopes because it takes longer times to collect the same number of photons at each emission wavelength as in a broad bandwidth. Here, we demonstrate an optical micro-spectroscopic scheme that employs a laser beam shaped into a line to excite in parallel multiple sample voxels. The method presents dramatically increased sensitivity and/or acquisition speed and, at the same time, has excellent spatial and spectral resolution, similar to point-scan configurations. When applied to FRET imaging using an oligomeric FRET construct expressed in living cells and consisting of a FRET acceptor linked to three donors, the technique based on line-shaped excitation provides higher accuracy compared to the point-scan approach, and it reduces artifacts caused by photobleaching and other undesired photophysical effects.

  18. Interaction of an antiepileptic drug, lamotrigine with human serum albumin (HSA): Application of spectroscopic techniques and molecular modeling methods.

    PubMed

    Poureshghi, Fatemeh; Ghandforoushan, Parisa; Safarnejad, Azam; Soltani, Somaieh

    2017-01-01

    Lamotrigine (an epileptic drug) interaction with human serum albumin (HSA) was investigated by fluorescence, UV-Vis, FTIR, CD spectroscopic techniques, and molecular modeling methods. Binding constant (Kb) of 5.74×10(3) and number of binding site of 0.97 showed that there is a slight interaction between lamotrigine and HSA. Thermodynamic studies was constructed using the flourimetric titrations in three different temperatures and the resulted data used to calculate the parameters using Vant Hoff equation. Decreased Stern Volmer quenching constant by enhanced temperature revealed the static quenching mechanism. Negative standard enthalpy (ΔH) and standard entropy (ΔS) changes indicated that van der Waals interactions and hydrogen bonds were dominant forces which facilitate the binding of Lamotrigine to HSA, the results were confirmed by molecular docking studies which showed no hydrogen binding. The FRET studies showed that there is a possibility of energy transfer between Trp214 and lamotrigine. Also the binding of lamotrigine to HSA in the studied concentrations was not as much as many other drugs, but the secondary structure of the HSA was significantly changed following the interaction in a way that α-helix percentage was reduced from 67% to 57% after the addition of lamotrigine in the molar ratio of 4:1 to HSA. According to the docking studies, lamotrigine binds to IB site preferably.

  19. Study on the interaction between bovine serum albumin and CdTe quantum dots with spectroscopic techniques

    NASA Astrophysics Data System (ADS)

    Liang, Jiangong; Cheng, Yanping; Han, Heyou

    2008-12-01

    The interaction between bovine serum albumin (BSA) and CdTe quantum dots (QDs) was studied by fluorescence, UV-vis and Raman spectroscopic techniques. The results showed that the fluorescence of BSA was strongly quenched by CdTe QDs. The quenching mechanism was discussed to be a static quenching procedure, which was proved by the quenching rate constant ( Kq) and UV-vis absorption spectra. According to Lineweaver-Burk equations at different temperatures, the thermodynamic parameters, Δ H θ, Δ S θ and Δ G θ were observed to be -23.69 kJ mol -1, 48.39 J mol -1 K -1 and -38.04 kJ mol -1, respectively. The binding constant ( KA) and the number of binding sites ( n) were obtained by Scatchard equation. It was found that hydrophobic force and sulfhydryl group played a key role in the interaction process. Further results from Raman spectra indicated that the α-helical content in BSA reduced after binding with CdTe QDs.

  20. Conformers of β-aminoisobutyric acid probed by jet-cooled microwave and matrix isolation infrared spectroscopic techniques.

    PubMed

    Kuş, N; Sharma, A; Peña, I; Bermúdez, M C; Cabezas, C; Alonso, J L; Fausto, R

    2013-04-14

    β-aminoisobutyric acid (BAIBA) has been studied in isolation conditions: in the gas phase and trapped into a cryogenic N2 matrix. A solid sample of the compound was vaporized by laser ablation and investigated through their rotational spectra in a supersonic expansion using two different spectroscopic techniques: broadband chirped pulse Fourier transform microwave spectroscopy and conventional molecular beam Fourier transform microwave spectroscopy. Four conformers with structures of two types could be successfully identified by comparison of the experimental rotational and (14)N nuclear quadruple coupling constants with those predicted theoretically: type A, bearing an OH⋯N intramolecular hydrogen bond and its carboxylic group in the trans geometry (H-O-C=O dihedral ∼180°), and type B, having an NH⋯O bond and the cis arrangement of the carboxylic group. These two types of conformers could also be trapped from the gas phase into a cryogenic N2 matrix and probed by Fourier transform infrared (IR) spectroscopy. In situ irradiation of BAIBA isolated in N2 matrix of type B conformers using near-IR radiation tuned at the frequency of the O-H stretching 1st overtone (∼6930 cm(-1)) of these forms allowed to selectively convert them into type A conformers and into a new type of conformers of higher energy (type D) bearing an NH⋯O=C bond and a O-H "free" trans carboxylic group.

  1. Conformers of β-aminoisobutyric acid probed by jet-cooled microwave and matrix isolation infrared spectroscopic techniques

    NASA Astrophysics Data System (ADS)

    Kuş, N.; Sharma, A.; Peña, I.; Bermúdez, M. C.; Cabezas, C.; Alonso, J. L.; Fausto, R.

    2013-04-01

    β-aminoisobutyric acid (BAIBA) has been studied in isolation conditions: in the gas phase and trapped into a cryogenic N2 matrix. A solid sample of the compound was vaporized by laser ablation and investigated through their rotational spectra in a supersonic expansion using two different spectroscopic techniques: broadband chirped pulse Fourier transform microwave spectroscopy and conventional molecular beam Fourier transform microwave spectroscopy. Four conformers with structures of two types could be successfully identified by comparison of the experimental rotational and 14N nuclear quadruple coupling constants with those predicted theoretically: type A, bearing an OH⋯N intramolecular hydrogen bond and its carboxylic group in the trans geometry (H-O-C=O dihedral ˜180°), and type B, having an NH⋯O bond and the cis arrangement of the carboxylic group. These two types of conformers could also be trapped from the gas phase into a cryogenic N2 matrix and probed by Fourier transform infrared (IR) spectroscopy. In situ irradiation of BAIBA isolated in N2 matrix of type B conformers using near-IR radiation tuned at the frequency of the O-H stretching 1st overtone (˜6930 cm-1) of these forms allowed to selectively convert them into type A conformers and into a new type of conformers of higher energy (type D) bearing an NH⋯O=C bond and a O-H "free" trans carboxylic group.

  2. Measurements of the aerosol chemical composition and mixing state in the Po Valley using multiple spectroscopic techniques

    NASA Astrophysics Data System (ADS)

    Decesari, S.; Allan, J.; Plass-Duelmer, C.; Williams, B. J.; Paglione, M.; Facchini, M. C.; O'Dowd, C.; Harrison, R. M.; Gietl, J. K.; Coe, H.; Giulianelli, L.; Gobbi, G. P.; Lanconelli, C.; Carbone, C.; Worsnop, D.; Lambe, A. T.; Ahern, A. T.; Moretti, F.; Tagliavini, E.; Elste, T.; Gilde, S.; Zhang, Y.; Dall'Osto, M.

    2014-04-01

    The use of co-located multiple spectroscopic techniques can provide detailed information on the atmospheric processes regulating aerosol chemical composition and mixing state. So far, field campaigns heavily equipped with aerosol mass spectrometers have been carried out mainly in large conurbations and in areas directly affected by their outflow, whereas lesser efforts have been dedicated to continental areas characterized by a less dense urbanization. We present here the results obtained in San Pietro Capofiume, which is located in a sparsely inhabited sector of the Po Valley, Italy. The experiment was carried out in summer 2009 in the framework of the EUCAARI project ("European Integrated Project on Aerosol, Cloud Climate Aerosol Interaction"). For the first time in Europe, six state-of-the-art techniques were used in parallel: (1) on-line TSI aerosol time-of-flight mass spectrometer (ATOFMS), (2) on-line Aerodyne high-resolution time-of-flight aerosol mass spectrometer (HR-TOF-AMS), (3) soot particle aerosol mass spectrometer (SP-AMS), (4) on-line high resolution time-of-flight mass spectrometer-thermal desorption aerosol gas chromatograph (HR-ToFMS-TAG), (5) off-line twelve-hour resolution proton nuclear magnetic resonance (H-NMR) spectroscopy, and (6) chemical ionization mass spectrometry (CIMS) for the analysis of gas-phase precursors of secondary aerosol. Data from each aerosol spectroscopic method were analysed individually following ad-hoc tools (i.e. PMF for AMS, Art-2a for ATOFMS). The results obtained from each techniques are herein presented and compared. This allows us to clearly link the modifications in aerosol chemical composition to transitions in air mass origin and meteorological regimes. Under stagnant conditions, atmospheric stratification at night and early morning hours led to the accumulation of aerosols produced by anthropogenic sources distributed over the Po Valley plain. Such aerosols include primary components such as black carbon (BC

  3. MnO spin-wave dispersion curves from neutron powder diffraction

    SciTech Connect

    Goodwin, Andrew L.; Dove, Martin T.; Tucker, Matthew G.; Keen, David A.

    2007-02-15

    We describe a model-independent approach for the extraction of spin-wave dispersion curves from powder neutron total scattering data. Our approach is based on a statistical analysis of real-space spin configurations to calculate spin-dynamical quantities. The RMCPROFILE implementation of the reverse Monte Carlo refinement process is used to generate a large ensemble of supercell spin configurations from MnO powder diffraction data collected at 100 K. Our analysis of these configurations gives spin-wave dispersion curves for MnO that agree well with those determined independently using neutron triple-axis spectroscopic techniques.

  4. Maneuver reconstruction techniques for open-loop spin-stabilized spacecraft

    NASA Technical Reports Server (NTRS)

    Frauenholz, R. B.

    1980-01-01

    The Pioneer missions were supported by spin-stabilized spacecraft designs using open-loop control and blow-down propulsion subsystems. Reliable estimates of the ever-changing performance inherent to these subsystems were needed to effectively design and reconstruct trajectory correction maneuver (TCM) strategies. These performance updates were obtained by adjusting model parameters to match independent telemetric and radiometric observations to define the simultaneous changes in attitude, velocity, and spin rate during a maneuver sequence.

  5. Study of anisotropy of spin cast and vapor deposited polyimide films using internal reflection techniques

    SciTech Connect

    Liberman, V.

    1996-11-01

    We have compared anisotropy of spin cast and vapor deposited polyimide (VDP) films, using internal reflection infrared spectroscopy. The films were deposited directly on the internal reflection element. We find that spin cast films are more anisotropic than their VDP counterparts, with the polyimide chains tending to align parallel to the substrate. Both films are found to contain more and less ordered regions. Within the ordered regions, the plane of the phenyl ring tends to align parallel to the substrate.

  6. A comparison investigation of DNP-binding effects to HSA and HTF by spectroscopic and molecular modeling techniques.

    PubMed

    Zolfagharzadeh, Mahboobeh; Pirouzi, Maliheh; Asoodeh, Ahmad; Saberi, Mohammad Reza; Chamani, Jamshidkhan

    2014-12-01

    This paper describes the interaction between 2,4-dinitrophenol (DNP) with the two drug carrier proteins - human serum albumin (HSA) and human holo transferrin (HTF). Hence, binding characteristics of DNP to HSA and HTF were analyzed by spectroscopic and molecular modeling techniques. Based on results obtained from fluorescence spectroscopy, DNP had a strong ability to quench the intrinsic fluorescence of HSA and HTF through a static quenching procedure. The binding constant and the number of binding sites were calculated as 2.3 × 10(11) M(-1) and .98 for HSA, and 1.7 × 10(11) M(-1) and 1.06 for HTF, respectively. In addition, synchronous fluorescence results showed that the microenvironment of Trp had a slight tendency of increasing its hydrophobicity, whereas the microenvironment of the Tyr residues of HSA did not change and that of HTF showed a significant trend (red shift of about 4 nm) of an increase in polarity. The distance between donor and acceptor was obtained by the Förster energy according to fluorescence resonance energy transfer, and was found to be 3.99 and 3.72 nm for HSA and HTF, respectively. The critical induced aggregation concentration (CCIAC) of the drug on both proteins was determined and confirmed by an inflection point of the zeta potential behavior. Circular dichroism data revealed that the presence of DNP caused a decrease of the α-helical content of HSA and HTF, and induced a remarkable mild denaturation of both proteins. The molecular modeling data confirmed our experimental results. This study is deemed useful for determining drug dosage.

  7. Application of phosphorus-31 and aluminum-27 NMR spectroscopic techniques to study aqueous and methanolic solutions of tetraphenylammonium aluminophosphate

    NASA Astrophysics Data System (ADS)

    Goudarzi, Nasser; Amin, Amir H.

    2017-01-01

    In this work, aluminum-27 and phosphorus-31 NMR spectroscopic techniques were used to investigate and characterize the distribution of aluminophosphate (AlPO) species soluble in the aqueous and methanolic solutions of tetraphenylammonium (TPhA) chloride. The reaction between hexaaquaaluminum cations, [A1(H2O)6]3+, and different phosphate ligands such as H3PO4, H2PO4-, and the acidic dimers H6P2O8 and H5P2O8- resulted in the formation of the soluble AlPO cations. The effective aluminum-27 and phosphorous-31 NMR spectroscopies can be employed to characterize the species present in a solution. Assignment of the peaks present in the aluminum-27 NMR spectra to the aluminate species or aluminate connectivities was done to acquire information about different AlPO complexes. Some resonance lines were observed in the phosphorus-31 {1H} NMR spectra, indicating the existence of different complexes in the AlPO solutions. Some peaks were observed in the methanolic solutions of AlPO at the chemical shifts of -0.41, -6.4, -7.5, -7.9, -13.1, -13.9, -16.6, -18.1, and -20.6 ppm. Four additional peaks were also observed in the phosphorus-31 {1H} NMR spectra of the methanolic solutions of AlPO, whose intensities changed with changes in the methanol:water volume ratio; they were observed in methanol but not in aqueous AlPO.

  8. Measurements of the aerosol chemical composition and mixing state in the Po Valley using multiple spectroscopic techniques

    NASA Astrophysics Data System (ADS)

    Decesari, S.; Allan, J.; Plass-Duelmer, C.; Williams, B. J.; Paglione, M.; Facchini, M. C.; O'Dowd, C.; Harrison, R. M.; Gietl, J. K.; Coe, H.; Giulianelli, L.; Gobbi, G. P.; Lanconelli, C.; Carbone, C.; Worsnop, D.; Lambe, A. T.; Ahern, A. T.; Moretti, F.; Tagliavini, E.; Elste, T.; Gilge, S.; Zhang, Y.; Dall'Osto, M.

    2014-11-01

    The use of co-located multiple spectroscopic techniques can provide detailed information on the atmospheric processes regulating aerosol chemical composition and mixing state. So far, field campaigns heavily equipped with aerosol mass spectrometers have been carried out mainly in large conurbations and in areas directly affected by their outflow, whereas lesser efforts have been dedicated to continental areas characterised by a less dense urbanisation. We present here the results obtained at a background site in the Po Valley, Italy, in summer 2009. For the first time in Europe, six state-of-the-art spectrometric techniques were used in parallel: aerosol time-of-flight mass spectrometer (ATOFMS), two aerosol mass spectrometers (high-resolution time-of-flight aerosol mass spectrometer - HR-ToF-AMS and soot particle aerosol mass spectrometer - SP-AMS), thermal desorption aerosol gas chromatography (TAG), chemical ionisation mass spectrometry (CIMS) and (offline) proton nuclear magnetic resonance (1H-NMR) spectroscopy. The results indicate that, under high-pressure conditions, atmospheric stratification at night and early morning hours led to the accumulation of aerosols produced by anthropogenic sources distributed over the Po Valley plain. Such aerosols include primary components such as black carbon (BC), secondary semivolatile compounds such as ammonium nitrate and amines and a class of monocarboxylic acids which correspond to the AMS cooking organic aerosol (COA) already identified in urban areas. In daytime, the entrainment of aged air masses in the mixing layer is responsible for the accumulation of low-volatility oxygenated organic aerosol (LV-OOA) and also for the recycling of non-volatile primary species such as black carbon. According to organic aerosol source apportionment, anthropogenic aerosols accumulating in the lower layers overnight accounted for 38% of organic aerosol mass on average, another 21% was accounted for by aerosols recirculated in

  9. a New Hybrid Heuristic Technique for Unit Commitment Considering Spinning Reserve Probability

    NASA Astrophysics Data System (ADS)

    Abdollahi, A.; Ehsan, M.; Rashidinejad, M.; Purakbari-Kasmaie, M.

    2009-08-01

    This paper proposes a new approach for solving generation scheduling and ramp rate constrained unit commitment with considering spinning reserve probability. In order to simulate the probability of reserve in the formulation, the estimated probability that spinning reserve is called and generated has been considered. A hybrid heuristic method between genetic algorithm and lambdad iteration method is applied to solve the problem. The proposed approach is applied to two different cases such as a 10-unit base problem without considering probability of reserve and 10-unit problem with considering probability of reserve. The results are compared with other approaches results to exhibit the superiority of the proposed approach.

  10. Nondestructive and rapid concurrent estimation of paracetamol and nimesulide in their combined dosage form using Raman spectroscopic technique.

    PubMed

    Lakhwani, Gargi R; Sherikar, O D; Mehta, Priti J

    2013-03-01

    A rapid, nondestructive Raman spectroscopic method was developed for quantitative estimation of paracetamol and nimesulide in their combined dosage form. A Raman univariate calibration model was developed by measuring the peak intensities of paracetamol and nimesulide at 853 cm(-1) and 1336 cm(-1), respectively. The developed method was successfully applied for in situ, concurrent estimation of paracetamol and nimesulide in their combined dosage and method was also validated according to International Conference on Harmonisation guidelines. Thus, the developed Raman spectroscopic method can be applied for simultaneous estimation of paracetamol and nimesulide in their combined dosage form as a process analytical technology tool by pharmaceutical industries for routine quality control.

  11. Application of a new non-linear least squares velocity curve analysis technique for spectroscopic binary stars

    NASA Astrophysics Data System (ADS)

    Karami, K.; Mohebi, R.; Soltanzadeh, M. M.

    2008-11-01

    Using measured radial velocity data of nine double lined spectroscopic binary systems NSV 223, AB And, V2082 Cyg, HS Her, V918 Her, BV Dra, BW Dra, V2357 Oph, and YZ Cas, we find corresponding orbital and spectroscopic elements via the method introduced by Karami and Mohebi (Chin. J. Astron. Astrophys. 7:558, 2007a) and Karami and Teimoorinia (Astrophys. Space Sci. 311:435, 2007). Our numerical results are in good agreement with those obtained by others using more traditional methods.

  12. Dipolar effects on the critical fluctuations in Fe: Investigation by the neutron spin-echo technique MIEZE

    NASA Astrophysics Data System (ADS)

    Kindervater, J.; Säubert, S.; Böni, P.

    2017-01-01

    Iron is one of the archetypical ferromagnets to study the critical fluctuations at a continuous phase transition thus serving as a model system for the application of scaling theory. We report a comprehensive study of the critical dynamics at the transition from the ferro- to the paramagnetic phase in Fe, employing the high-resolution neutron spin-echo technique, modulated intensity of zero effort (MIEZE). The results show that the dipolar interactions lead to an additional damping of the critical spin fluctuations at small momentum transfers q . The results agree essentially with scaling theory if the dipolar interactions are taken into account by means of the mode-coupling equations. However, in contrast to expectations, the dipolar wave number qD that plays a central role in the scaling function f (κ /q ,qD/κ ) becomes temperature dependent. In the limit of small q the critical exponent z crosses over from 2.5 to 2.0.

  13. Spin wave study and optical properties in Fe-doped ZnO thin films prepared by spray pyrolysis technique

    NASA Astrophysics Data System (ADS)

    Lmai, F.; Moubah, R.; El Amiri, A.; Abid, Y.; Soumahoro, I.; Hassanain, N.; Colis, S.; Schmerber, G.; Dinia, A.; Lassri, H.

    2016-07-01

    We investigate the magnetic and optical properties of Zn1-xFexO (x = 0, 0.03, 0.05, and 0.07) thin films grown by spray pyrolysis technique. The magnetization as a function of temperature [M (T)] shows a prevailing paramagnetic contribution at low temperature. By using spin wave theory, we separate the M (T) curve in two contributions: one showing intrinsic ferromagnetism and one showing a purely paramagnetic behavior. Furthermore, it is shown that the spin wave theory is consistent with ab-initio calculations only when oxygen vacancies are considered, highlighting the key role played by structural defects in the mechanism driving the observed ferromagnetism. Using UV-visible measurements, the transmittance, reflectance, band gap energy, band tail, dielectric coefficient, refractive index, and optical conductivity were extracted and related to the variation of the Fe content.

  14. Spectroscopic data, spin-orbit functions, and revised analysis of strong perturbative interactions for the A {sup 1{Sigma}+} and b {sup 3{Pi}} states of RbCs

    SciTech Connect

    Docenko, O.; Tamanis, M.; Ferber, R.; Bergeman, T.; Kotochigova, S.; Stolyarov, A. V.

    2010-04-15

    The current interest in producing ultracold RbCs molecules by optical excitation from weakly bound Feshbach resonances and stimulated decay to the absolute ground state requires detailed analyses of the intermediate excited states. In this study, we present two sets of experimental Fourier-transform spectroscopic data of the A {sup 1{Sigma}+}-b {sup 3{Pi}} complex. The A-b mixed vibrational levels are the most likely candidates to be intermediates in the molecular formation. The more recent and more accurate data set is from mixed A-b{yields}X transitions, while the second is derived in large part from (4) {sup 1{Sigma}+{yields}}A-b emission and extends to higher A-b energy levels. From a detailed analysis of the spectroscopic data we obtain term values which allow one to construct potentials and spin-orbit functions. Vibrational numbering of the A state has been raised by one quantum over a previous report [T. Bergeman et al., Phys. Rev. A 67, 050501 (2003)] while the numbering of the b state is established with a considerable degree of certainty with help of data on the {sup 85}Rb{sup 133}Cs and {sup 87}Rb{sup 133}Cs isotopomers. In addition, we have performed calculations of spin-orbit functions by two distinct methods. The fitted spin-orbit coupling matrix element between the two {Omega}{sup p}=0{sup +} states, A {sup 1{Sigma}+} and b {sup 3{Pi}}{sub 0+}, happens to agree rather well with the results from both of these methods, while for the diagonal b {sup 3{Pi}} state spin-orbit function, the fitted function agrees fairly well with that obtained by the other method.

  15. New Techniques to Test Spin-Gravity Coupling with Atomic Clock

    NASA Technical Reports Server (NTRS)

    Maleki, L.

    2000-01-01

    Recent advances in laser technology have produced the opportunity to realize more stable and accurate atomic clocks, by laser excitation, manipulation and cooling of atoms. In this paper we will describe a new scheme based on the use of lasers with atomic clocks to increase the sensitivity of experimental search for a spin-gravity coupling.

  16. Study of Low Energy Electron Inelastic Scattering Mechanisms Using Spin Sensitive Techniques

    NASA Astrophysics Data System (ADS)

    Hsu, Hongbing

    1995-01-01

    Spin sensitive electron spectroscopies were used to study low energy electron inelastic scattering from metal surfaces and thin films. In these experiments, a beam of spin polarized electrons from a GaAs source is directed on the sample surface, and the spin polarization and intensity are measured as a function of energy loss and scattering angle by a Mott electron polarimeter coupled with a concentric hemispherical energy analyzer. Systematic studies of the angular dependence of inelastically scattered electrons were conducted on a Cu(100) surface, and Mo/Cu(100), non-magnetized Fe/Cu(100), and Co/Cu(100) films. The polarization and intensity of scattered electrons were measured as function of energy loss and scattering angle. Further studies were also conducted on Ag(100) surface and amorphous Cu/Ag(100) films. From the experimental results, the angular distributions of dipole and impact scattered electrons can be determined individually and both are found to peak in the specular scattering direction. Preliminary studies were conducted on magnetized Co/Cu(100) films. The spin dependent scattering intensity asymmetry was measured, with a clearly observable peak at energy loss of ~1 eV, which coincides with the band splitting. The polarizations of secondary electrons produced by an unpolarized primary beam were also measured. The polarizations can be related to the band polarization of magnetized cobalt films.

  17. Spectroscopic analysis of solar and cosmic X-ray spectra. 1: The nature of cosmic X-ray spectra and proposed analytical techniques

    NASA Technical Reports Server (NTRS)

    Walker, A. B. C., Jr.

    1975-01-01

    Techniques for the study of the solar corona are reviewed as an introduction to a discussion of modifications required for the study of cosmic sources. Spectroscopic analysis of individual sources and the interstellar medium is considered. The latter was studied via analysis of its effect on the spectra of selected individual sources. The effects of various characteristics of the ISM, including the presence of grains, molecules, and ionization, are first discussed, and the development of ISM models is described. The expected spectral structure of individual cosmic sources is then reviewed with emphasis on supernovae remnants and binary X-ray sources. The observational and analytical requirements imposed by the characteristics of these sources are identified, and prospects for the analysis of abundances and the study of physical parameters within them are assessed. Prospects for the spectroscopic study of other classes of X-ray sources are also discussed.

  18. The use of simulation in the EPR spin probe technique for detection of irradiated seeds.

    PubMed

    Sünnetçioğlu, M M; Dadaylı, D

    2000-10-02

    An electron paramagnetic resonance (EPR) spin probe study of irradiated wheat seeds was performed depending on irradiation dose. The structural changes in the membrane integrity were followed using aqueous solutions of 4-hydroxy-TEMPO (TANOL) spin probe and a line broadening material. In the studies dry seed embryos were kept in these solutions for 150 min. The spectra were recorded at various times of air drying process. The simulation of these spectra indicated a decrease in the water content of the embryos depending on the increasing irradiation dose. This indicates the increase in the permeability of the membranes as a result of the radiation damage. From the decay curves it is possible to determine about irradiation dose, however, this approach is not very successful at close irradiation doses.

  19. Study of coal tar pitch microstructure by using spin probe technique

    SciTech Connect

    Shklyaev, A.A.; Ugay, M.Y.

    1994-12-31

    One of the copper porphyrin complexes has been adopted as a spin probe in order to provide insight into the nature of paramagnetic species of coal tar pitch. It was found that there are three kinds of nonequivalent radical centers displaying a different sensitivity to the spin probes. The majority of radical centers in original coal tar pitch cannot be detected in E.S.R. spectra due to considerable broadening of its lines. These invisible centers give rise to sudden broadening of E.S.R. signals of complex dissolved in the pitch heated over 400 C. The questions regarding the nature of radical states and the reason of abrupt high temperature broadening of pitch signals are discussed.

  20. Use of epr spin-trapping techniques to detect radicals from rat lung lavage fluid following sulfur mustard vapor exposure

    SciTech Connect

    Anderson, D.R.; Yourick, J.J.; Arroyo, C.M.; Young, G.D.; Harris, L.W.

    1993-05-13

    Although well known for skin vesicating properties, pulmonary damage and associated infections account for most of the mortality associated with sulfur mustard (HD). We have employed an in vivo HD vapor exposure model, bronchoalveolar lavage and histopathology in conjunction with electron paramagnetic resonance (EPR) techniques to provide evidence for HD-induced (free radical/lipid peroxidation associated) lung injury. Anesthetized rats were intratracheally intubated and exposed to 0.35 mg HD vapor over 50 min. Immediately, 1 hr or 24 hr after exposure, lungs were lavaged with the spin trap, alpha-phenyl-t-butyl nitrone (PBN; 0.35 mg/ml). Recovered lavage fluid was assayed by EPR spectroscopy for radical spin adducts. Airway lipid extracts were assayed for thiobarbituric acid reactive products (TBARs); while separate groups of rats were used to evaluate histopathology. EPR results show the presence of an ascorbyl radical at 1 and 24 hr, and a carbon centered PBN spin adduct at 24 hr, both indicative of lipid peroxidation. TBAR (A532nm) formation was also detected at 24 hr. Histopathology revealed multifocal separation of the bronchial epithelium from the submucosa with little or no alveolar involvement at 24 hrs. These studies provide evidence that HD may affect lungs by a free radical mechanism which produces membrane and other tissue damage.

  1. Using non-invasive molecular spectroscopic techniques to detect unique aspects of protein Amide functional groups and chemical properties of modeled forage from different sourced-origins.

    PubMed

    Ji, Cuiying; Zhang, Xuewei; Yu, Peiqiang

    2016-03-05

    The non-invasive molecular spectroscopic technique-FT/IR is capable to detect the molecular structure spectral features that are associated with biological, nutritional and biodegradation functions. However, to date, few researches have been conducted to use these non-invasive molecular spectroscopic techniques to study forage internal protein structures associated with biodegradation and biological functions. The objectives of this study were to detect unique aspects and association of protein Amide functional groups in terms of protein Amide I and II spectral profiles and chemical properties in the alfalfa forage (Medicago sativa L.) from different sourced-origins. In this study, alfalfa hay with two different origins was used as modeled forage for molecular structure and chemical property study. In each forage origin, five to seven sources were analyzed. The molecular spectral profiles were determined using FT/IR non-invasive molecular spectroscopy. The parameters of protein spectral profiles included functional groups of Amide I, Amide II and Amide I to II ratio. The results show that the modeled forage Amide I and Amide II were centered at 1653 cm(-1) and 1545 cm(-1), respectively. The Amide I spectral height and area intensities were from 0.02 to 0.03 and 2.67 to 3.36 AI, respectively. The Amide II spectral height and area intensities were from 0.01 to 0.02 and 0.71 to 0.93 AI, respectively. The Amide I to II spectral peak height and area ratios were from 1.86 to 1.88 and 3.68 to 3.79, respectively. Our results show that the non-invasive molecular spectroscopic techniques are capable to detect forage internal protein structure features which are associated with forage chemical properties.

  2. Using non-invasive molecular spectroscopic techniques to detect unique aspects of protein Amide functional groups and chemical properties of modeled forage from different sourced-origins

    NASA Astrophysics Data System (ADS)

    Ji, Cuiying; Zhang, Xuewei; Yu, Peiqiang

    2016-03-01

    The non-invasive molecular spectroscopic technique-FT/IR is capable to detect the molecular structure spectral features that are associated with biological, nutritional and biodegradation functions. However, to date, few researches have been conducted to use these non-invasive molecular spectroscopic techniques to study forage internal protein structures associated with biodegradation and biological functions. The objectives of this study were to detect unique aspects and association of protein Amide functional groups in terms of protein Amide I and II spectral profiles and chemical properties in the alfalfa forage (Medicago sativa L.) from different sourced-origins. In this study, alfalfa hay with two different origins was used as modeled forage for molecular structure and chemical property study. In each forage origin, five to seven sources were analyzed. The molecular spectral profiles were determined using FT/IR non-invasive molecular spectroscopy. The parameters of protein spectral profiles included functional groups of Amide I, Amide II and Amide I to II ratio. The results show that the modeled forage Amide I and Amide II were centered at 1653 cm- 1 and 1545 cm- 1, respectively. The Amide I spectral height and area intensities were from 0.02 to 0.03 and 2.67 to 3.36 AI, respectively. The Amide II spectral height and area intensities were from 0.01 to 0.02 and 0.71 to 0.93 AI, respectively. The Amide I to II spectral peak height and area ratios were from 1.86 to 1.88 and 3.68 to 3.79, respectively. Our results show that the non-invasive molecular spectroscopic techniques are capable to detect forage internal protein structure features which are associated with forage chemical properties.

  3. Note: electrical detection and quantification of Spin Rectification Effect enabled by shorted microstrip transmission line technique.

    PubMed

    Soh, Wee Tee; Peng, Bin; Chai, Guozhi; Ong, C K

    2014-02-01

    We describe a shorted microstrip method for the sensitive quantification of Spin Rectification Effect (SRE). SRE for a Permalloy (Ni80Fe20) thin film strip sputtered onto SiO2 substrate is demonstrated. Our method obviates the need for simultaneous lithographic patterning of the sample and transmission line, therefore greatly simplifying the SRE measurement process. Such a shorted microstrip method can allow different contributions to SRE (anisotropic magnetoresistance, Hall effect, and anomalous Hall effect) to be simultaneously determined. Furthermore, SRE signals from unpatterned 50 nm thick Permalloy films of area dimensions 5 mm × 10 mm can even be detected.

  4. Note: Electrical detection and quantification of spin rectification effect enabled by shorted microstrip transmission line technique

    SciTech Connect

    Soh, Wee Tee; Ong, C. K.; Peng, Bin; Chai, Guozhi

    2014-02-15

    We describe a shorted microstrip method for the sensitive quantification of Spin Rectification Effect (SRE). SRE for a Permalloy (Ni{sub 80}Fe{sub 20}) thin film strip sputtered onto SiO{sub 2} substrate is demonstrated. Our method obviates the need for simultaneous lithographic patterning of the sample and transmission line, therefore greatly simplifying the SRE measurement process. Such a shorted microstrip method can allow different contributions to SRE (anisotropic magnetoresistance, Hall effect, and anomalous Hall effect) to be simultaneously determined. Furthermore, SRE signals from unpatterned 50 nm thick Permalloy films of area dimensions 5 mm × 10 mm can even be detected.

  5. Analysis of hysteretic spin transition and size effect in 3D spin crossover compounds investigated by Monte Carlo Entropic sampling technique in the framework of the Ising-type model

    NASA Astrophysics Data System (ADS)

    Chiruta, D.; Linares, J.; Dahoo, P. R.; Dimian, M.

    2015-02-01

    In spin crossover (SCO) systems, the shape of the hysteresis curves are closely related to the interactions between the molecules, which these play an important role in the response of the system to an external parameter. The effects of short-range interactions on the different shape of the spin transition phenomena were investigated. In this contribution we solve the corresponding Hamiltonian for a three-dimensional SCO system taking into account short-range and long-range interaction using a biased Monte Carlo entropic sampling technique and a semi-analytical method. We discuss the competition between the two interactions which governs the low spin (LS) - high spin (HS) process for a three-dimensional network and the cooperative effects. We demonstrate a strong correlation between the shape of the transition and the strength of short-range interaction between molecules and we identified the role of the size for SCO systems.

  6. The origin, composition and history of cometary ices from spectroscopic studies

    NASA Technical Reports Server (NTRS)

    Allamandola, L. J.

    1989-01-01

    The spectroscopic analysis of pristine cometary material provides a very important probe of the chemical identity of the material as well as of the physical and chemical conditions which prevailed during the comet's history. Concerning classical spectroscopy, the spectral regions which will most likely prove most useful are the infrared, the visible and ultraviolet. Newer spectroscopic techniques which have the potential to provide equally important information include nuclear magnetic resonance (NMR) and electron spin resonance (ESR). Each technique is summarized with emphasis placed on the kind of information which can be obtained.

  7. Development of a 3He nuclear spin flip system on an in-situ SEOP 3He spin filter and demonstration for a neutron reflectometer and magnetic imaging technique

    NASA Astrophysics Data System (ADS)

    Hayashida, H.; Oku, T.; Kira, H.; Sakai, K.; Hiroi, K.; Ino, T.; Shinohara, T.; Imagawa, T.; Ohkawara, M.; Ohoyama, K.; Kakurai, K.; Takeda, M.; Yamazaki, D.; Oikawa, K.; Harada, M.; Miyata, N.; Akutsu, K.; Mizusawa, M.; Parker, J. D.; Matsumoto, Y.; Zhang, S.; Suzuki, J.; Soyama, K.; Aizawa, K.; Arai, M.

    2016-04-01

    We have been developing a 3He neutron spin filter (NSF) using the spin exchange optical pumping (SEOP) technique. The 3He NSF provides a high-energy polarized neutron beam with large beam size. Moreover the 3He NSF can work as a π-flipper for a polarized neutron beam by flipping the 3He nuclear spin using a nuclear magnetic resonance (NMR) technique. For NMR with the in-situ SEOP technique, the polarization of the laser must be reversed simultaneously because a non-reversed laser reduces the polarization of the spin-flipped 3He. To change the polarity of the laser, a half-wavelength plate was installed. The rotation angle of the half-wavelength plate was optimized, and a polarization of 97% was obtained for the circularly polarized laser. The 3He polarization reached 70% and was stable over one week. A demonstration of the 3He nuclear spin flip system was performed at the polarized neutron reflectometer SHARAKU (BL17) and NOBORU (BL10) at J-PARC. Off-specular measurement from a magnetic Fe/Cr thin film and magnetic imaging of a magnetic steel sheet were performed at BL17 and BL10, respectively.

  8. Assessment of natural radioactivity and function of minerals in soils of Yelagiri hills, Tamilnadu, India by Gamma Ray spectroscopic and Fourier Transform Infrared (FTIR) techniques with statistical approach

    NASA Astrophysics Data System (ADS)

    Chandrasekaran, A.; Ravisankar, R.; Rajalakshmi, A.; Eswaran, P.; Vijayagopal, P.; Venkatraman, B.

    2015-02-01

    Gamma Ray and Fourier Transform Infrared (FTIR) spectroscopic techniques were used to evaluate the natural radioactivity due to natural radionuclides and mineralogical characterization in soils of Yelagiri hills, Tamilnadu, India. Various radiological parameters were calculated to assess the radiation hazards associated with the soil. The distribution pattern of activity due to natural radionuclides is explained by Kriging method of mapping. Using FTIR spectroscopic technique the minerals such as quartz, microcline feldspar, orthoclase feldspar, kaolinite, montmorillonite, illite, and organic carbon were identified and characterized. The extinction coefficient values were calculated to know the relative distribution of major minerals such as quartz, microcline feldspar, orthoclase feldspar and kaolinite. The calculated values indicate that the amount of quartz is higher than orthoclase feldspar, microcline feldspar and much higher than kaolinite. Crystallinity index was calculated to know the crystalline nature of quartz. The result indicates that the presence of disordered crystalline quartz in soils. The relation between minerals and radioactivity was assessed by multivariate statistical analysis (Pearson's correlation and cluster analysis). The statistical analysis confirms that the clay mineral kaolinite and non-clay mineral quartz is the major factor than other major minerals to induce the important radioactivity variables and concentrations of uranium and thorium.

  9. Preparation techniques of the submicron lithium titanate materials by electro-spinning

    NASA Astrophysics Data System (ADS)

    Wang, Yudong; Yang, Kai; Gao, Fei; Liu, Hao; Zhang, Mingjie

    2017-01-01

    Combining sol-gel process and electro-spinning, the submicron lithium titanate materials are prepared with lithium acetate and titanium tetraisopropanolate respectively as the lithium and titanium sources, and polyvinylpyrrolidone (PVP) as the template. It's found by scanning electron microscope(SEM )that, the prepared lithium titanate materials are characterized by the fiber diameter 150~200nm, a large number of irregular indentations in the surface, and the larger specific surface area than that before calcination. The lithium titanate cell receives charge-discharge test and cyclic voltammetry. The capacity of the submicron lithium titanate materials is up to 160mAh·g-1 at the rate of 0.1C, and it's revealed by cyclic voltammetry that the cell in the charge or discharge process undergoes a single redox reaction, but having good reversibility.

  10. Spin-orbit scattering visualized in quasiparticle interference

    NASA Astrophysics Data System (ADS)

    Kohsaka, Y.; Machida, T.; Iwaya, K.; Kanou, M.; Hanaguri, T.; Sasagawa, T.

    2017-03-01

    In the presence of spin-orbit coupling, electron scattering off impurities depends on both spin and orbital angular momentum of electrons—spin-orbit scattering. Although some transport properties are subject to spin-orbit scattering, experimental techniques directly accessible to this effect are limited. Here we show that a signature of spin-orbit scattering manifests itself in quasiparticle interference (QPI) imaged by spectroscopic-imaging scanning tunneling microscopy. The experimental data of a polar semiconductor BiTeI are well reproduced by numerical simulations with the T -matrix formalism that include not only scalar scattering normally adopted but also spin-orbit scattering stronger than scalar scattering. To accelerate the simulations, we extend the standard efficient method of QPI calculation for momentum-independent scattering to be applicable even for spin-orbit scattering. We further identify a selection rule that makes spin-orbit scattering visible in the QPI pattern. These results demonstrate that spin-orbit scattering can exert predominant influence on QPI patterns and thus suggest that QPI measurement is available to detect spin-orbit scattering.

  11. Spin-Polarization-Induced Preedge Transitions in the Sulfur K-Edge XAS Spectra of Open-Shell Transition-Metal Sulfates: Spectroscopic Validation of σ-Bond Electron Transfer.

    PubMed

    Frank, Patrick; Szilagyi, Robert K; Gramlich, Volker; Hsu, Hua-Fen; Hedman, Britt; Hodgson, Keith O

    2017-02-06

    Sulfur K-edge X-ray absorption spectroscopy (XAS) spectra of the monodentate sulfate complexes [M(II)(itao)(SO4)(H2O)0,1] (M = Co, Ni, Cu) and [Cu(Me6tren)(SO4)] exhibit well-defined preedge transitions at 2479.4, 2479.9, 2478.4, and 2477.7 eV, respectively, despite having no direct metal-sulfur bond, while the XAS preedge of [Zn(itao)(SO4)] is featureless. The sulfur K-edge XAS of [Cu(itao)(SO4)] but not of [Cu(Me6tren)(SO4)] uniquely exhibits a weak transition at 2472.1 eV, an extraordinary 8.7 eV below the first inflection of the rising K-edge. Preedge transitions also appear in the sulfur K-edge XAS of crystalline [M(II)(SO4)(H2O)] (M = Fe, Co, Ni, and Cu, but not Zn) and in sulfates of higher-valent early transition metals. Ground-state density functional theory (DFT) and time-dependent DFT (TDDFT) calculations show that charge transfer from coordinated sulfate to paramagnetic late transition metals produces spin polarization that differentially mixes the spin-up (α) and spin-down (β) spin orbitals of the sulfate ligand, inducing negative spin density at the sulfate sulfur. Ground-state DFT calculations show that sulfur 3p character then mixes into metal 4s and 4p valence orbitals and various combinations of ligand antibonding orbitals, producing measurable sulfur XAS transitions. TDDFT calculations confirm the presence of XAS preedge features 0.5-2 eV below the rising sulfur K-edge energy. The 2472.1 eV feature arises when orbitals at lower energy than the frontier occupied orbitals with S 3p character mix with the copper(II) electron hole. Transmission of spin polarization and thus of radical character through several bonds between the sulfur and electron hole provides a new mechanism for the counterintuitive appearance of preedge transitions in the XAS spectra of transition-metal oxoanion ligands in the absence of any direct metal-absorber bond. The 2472.1 eV transition is evidence for further radicalization from copper(II), which extends across a

  12. Examination of optimum carrier materials and quantum dots for a quantum dot solar concentrator using spectroscopic techniques

    NASA Astrophysics Data System (ADS)

    Gallagher, S. J.; Rowan, B. C.; Doran, J.; Norton, B.

    2005-08-01

    Spectroscopic measurements have been undertaken for a range of different quantum dot (QD) types and transparent host materials for use in a novel solar energy-concentrating device, a Quantum Dot Solar Concentrator1 (QDSC). A QDSC comprises QDs seeded in materials such as plastics and glasses that are suitable for incorporation into buildings where photovoltaic cells attached to the edges convert direct and diffuse solar energy into electricity for use in the building. High transparency in the matrix material and QDs with a large Stokes shift are essential for an efficient QDSC. An optimum matrix material for a QDSC has been determined based on absorption characteristics and an optimum commercially available QD type has been chosen using steady-state absorption, photoluminescence and photoluminescence excitation spectroscopy of QDs in solution and solid matrices.

  13. Potential energy curves and spectroscopic parameters of the 24 Λ-S states and 54 Ω states of the F2 + cation including the spin-orbit coupling effect*

    NASA Astrophysics Data System (ADS)

    Liu, Hui; Shi, Deheng; Sun, Jinfeng; Zhu, Zunlue

    2016-11-01

    This work calculated the PECs of 24 Λ-S states and 54 Ω states of F2+ cation. The calculations were done with the CASSCF method, which was followed by the internally contracted MRCI approach. Core-valence correlation correction, scalar relativistic correction and basis set extrapolation were taken into account. Of these 24 Λ-S states, the 22Σg-, 22Σu-, 24Σg-, 14Δu, and 24Πg states were found to be repulsive. The X2Πg, A2Πu 14Δg, 14Πg and 24Πg states were found to be inverted with the spin-orbit coupling effect included. The 12Δg, 24Πu, 14Πg, 14Σu+, 22Πu, 14Σg-, 24Σu-, and 12Σg+ states were found to be weakly bound. The 24Σu- state had double wells. The avoided crossings of PECs were observed between the A2Πu and 22Πu states, the X2Πg and 22Πg states, the 12Σu- and 22Σu- states, the 14Πu and 24Πu states, and the 14Σ-g and 24Σ-g states. Some spectroscopic parameters were determined and the vibrational properties of several weakly-bound states were predicted. The spin-orbit coupling effect on the spectroscopic parameters was evaluated. Comparison with available experimental data shows that the methodology used in this paper is highly accurate for this system. Supplementary material in the form of one pdf file available from the Journal web page at: http://dx.doi.org/10.1140/epjd/e2016-70388-9

  14. A non-invasive thermal drift compensation technique applied to a spin-valve magnetoresistive current sensor.

    PubMed

    Sánchez Moreno, Jaime; Ramírez Muñoz, Diego; Cardoso, Susana; Casans Berga, Silvia; Navarro Antón, Asunción Edith; Peixeiro de Freitas, Paulo Jorge

    2011-01-01

    A compensation method for the sensitivity drift of a magnetoresistive (MR) Wheatstone bridge current sensor is proposed. The technique was carried out by placing a ruthenium temperature sensor and the MR sensor to be compensated inside a generalized impedance converter circuit (GIC). No internal modification of the sensor bridge arms is required so that the circuit is capable of compensating practical industrial sensors. The method is based on the temperature modulation of the current supplied to the bridge, which improves previous solutions based on constant current compensation. Experimental results are shown using a microfabricated spin-valve MR current sensor. The temperature compensation has been solved in the interval from 0 °C to 70 °C measuring currents from -10 A to +10 A.

  15. Anomaly Detection Techniques with Real Test Data from a Spinning Turbine Engine-Like Rotor

    NASA Technical Reports Server (NTRS)

    Abdul-Aziz, Ali; Woike, Mark R.; Oza, Nikunj C.; Matthews, Bryan L.

    2012-01-01

    Online detection techniques to monitor the health of rotating engine components are becoming increasingly attractive to aircraft engine manufacturers in order to increase safety of operation and lower maintenance costs. Health monitoring remains a challenge to easily implement, especially in the presence of scattered loading conditions, crack size, component geometry, and materials properties. The current trend, however, is to utilize noninvasive types of health monitoring or nondestructive techniques to detect hidden flaws and mini-cracks before any catastrophic event occurs. These techniques go further to evaluate material discontinuities and other anomalies that have grown to the level of critical defects that can lead to failure. Generally, health monitoring is highly dependent on sensor systems capable of performing in various engine environmental conditions and able to transmit a signal upon a predetermined crack length, while acting in a neutral form upon the overall performance of the engine system.

  16. Determination of photocarrier density under continuous photoirradiation using spectroscopic techniques as applied to polymer: Fullerene blend films

    SciTech Connect

    Kanemoto, Katsuichi Nakatani, Hitomi; Domoto, Shinya

    2014-10-28

    We propose a method to determine the density of photocarrier under continuous photoirradiation in conjugated polymers using spectroscopic signals obtained by photoinduced absorption (PIA) measurements. The bleaching signals in the PIA measurements of polymer films and the steady-state absorption signals of oxidized polymer solution are employed to determine the photocarrier density. The method is applied to photocarriers of poly (3-hexylthiophene) (P3HT) in a blended film consisting of P3HT and [6,6]-phenyl C61 butyric acid methyl ester (PCBM). The photocarrier density under continuous photoirradiation of 580 mW/cm{sup 2} is determined to be 3.5 × 10{sup 16 }cm{sup −3}. Using a trend of the carrier density increasing in proportion to the square root of photo-excitation intensity, we provide a general formula to estimate the photocarrier density under simulated 1 sun solar irradiation for the P3HT: PCBM film of an arbitrary thickness. We emphasize that the method proposed in this study enables an estimate of carrier density without measuring a current and can be applied to films with no electrodes as well as to devices.

  17. Investigation on the interaction between isorhamnetin and bovine liver catalase by spectroscopic techniques under different pH conditions.

    PubMed

    Yang, Yumin; Li, Daojin

    2016-08-01

    The binding of isorhamnetin to bovine liver catalase (BLC) was first investigated at 302, 310 and 318 K at pH 7.4 using spectroscopic methods including fluorescence spectra, circular dichroism (CD) and UV-vis absorption. Spectrophotometric observations are rationalized mainly in terms of a static quenching process. The binding constants and binding sites were evaluated by fluorescence quenching methods. Enzymatic activity of BLC in the absence and presence of isorhamnetin was measured using a UV/vis spectrophotometer. The result revealed that the binding of isorhamnetin to BLC led to a reduction in the activity of BLC. The positive entropy change and enthalpy change indicated that the interaction of isorhamnetin with BLC was mainly driven by hydrophobic forces. The distance r between the donor (BLC) and acceptor (isorhamnetin) was estimated to be 2.99 nm according to fluorescence resonance energy transfer. Fluorescence, synchronous fluorescence, and CD spectra showed no obvious change in the conformation of BLC upon the binding of isorhamnetin. In addition, the influence of pH on the binding of isorhamnetin to BLC was investigated and the binding ability of the drug to BLC deceased under other pH conditions (pH 9.0, 6.5, 5.0, 3.5, or 2.0) as compared with that at pH 7.4. Copyright © 2016 John Wiley & Sons, Ltd.

  18. Analytical performance of different X-ray spectroscopic techniques for the environmental monitoring of the recultivated uranium mine site

    NASA Astrophysics Data System (ADS)

    Alsecz, A.; Osán, J.; Kurunczi, S.; Alföldy, B.; Várhegyi, A.; Török, S.

    2007-08-01

    One uranium deposit exists in Hungary, with continuous radiological monitoring of the site. Nuclear spectroscopical methods are well established in order to study the problem concerning radionuclides. However, very limited information is available on the distribution and chemical form of uranium in the tailings sludge. In order to solve this complex analytical problem, a combination of different analytical methods is necessary. One of the most applied methods for studying the major elemental composition of particulate samples is electron probe microanalysis (EPMA). However, uranium and its daughter elements are often present only at trace amounts in the particles, below detection limit of EPMA. For most actinides that are long-lived radionuclides, microbeam X-ray fluorescence (μ-XRF) has superior sensitivity to determine elements in microparticles. Detection limits and applicability of EPMA and laboratory μ-XRF are discussed for localization of uranium-rich particles in the inhomogeneous tailings material. Laboratory μ-XRF provided an efficient way to identify these particles that can be easily relocated for further non-destructive microchemical investigations. Finally, for water analysis a simple and reliable method for U analysis is presented using total reflection X-ray fluorescence spectrometry (TXRF) that can be applied for on-site analysis in situations of accidental uranium contamination.

  19. Investigation into the interaction of losartan with human serum albumin and glycated human serum albumin by spectroscopic and molecular dynamics simulation techniques: A comparison study.

    PubMed

    Moeinpour, Farid; Mohseni-Shahri, Fatemeh S; Malaekeh-Nikouei, Bizhan; Nassirli, Hooriyeh

    2016-09-25

    The interaction between losartan and human serum albumin (HSA), as well as its glycated form (gHSA) was studied by multiple spectroscopic techniques and molecular dynamics simulation under physiological conditions. The binding information, including the binding constants, effective quenching constant and number of binding sites showed that the binding partiality of losartan to HSA was higher than to gHSA. The findings of three-dimensional fluorescence spectra demonstrated that the binding of losartan to HSA and gHSA would alter the protein conformation. The distances between Trp residue and the binding sites of the drug were evaluated on the basis of the Förster theory, and it was indicated that non-radiative energy transfer from HSA and gHSA to the losartan happened with a high possibility. According to molecular dynamics simulation, the protein secondary and tertiary structure changes were compared in HSA and gHSA for clarifying the obtained results.

  20. A homonuclear spin-pair filter for solid-state NMR based on adiabatic-passage techniques

    NASA Astrophysics Data System (ADS)

    Verel, René; Baldus, Marc; Ernst, Matthias; Meier, Beat H.

    1998-05-01

    A filtering scheme for the selection of spin pairs (and larger spin clusters) under fast magic-angle spinning is proposed. The scheme exploits the avoided level crossing in spin pairs during an adiabatic amplitude sweep through the so-called HORROR recoupling condition. The advantages over presently used double-quantum filters are twofold. (i) The maximum theoretical filter efficiency is, due to the adiabatic variation, 100% instead of 73% as for transient methods. (ii) Since the filter does not rely on the phase-cycling properties of the double-quantum coherence, there is no need to obtain the full double-quantum intensity for all spins in the sample at one single point in time. The only important requirement is that all coupled spins pass through a two-spin state during the amplitude sweep. This makes the pulse scheme robust with respect to rf-amplitude missetting, rf-field inhomogeneity and chemical-shift offset.

  1. Response to the Letter to the Editor by D. Richardson: Analysis of the Interaction of Dp44mT with Human Serum Albumin and Calf Thymus DNA Using Molecular Docking and Spectroscopic Techniques

    PubMed Central

    Xu, Zhongjie; Liu, Youxun; Zhou, Sufeng; Fu, Yun; Li, Changzheng

    2016-01-01

    This response refers to: Xu, Z.; Liu, Y.; Zhou, S.; Fu, Y.; Li, C. Analysis of the Interaction of Dp44mT with Human Serum Albumin and Calf Thymus DNA Using Molecular Docking and Spectroscopic Techniques. Int. J. Mol. Sci. 2016, 17, 1042. Merlot, A.M.; Sahni, S.; Lane, D.J.R.; Richardson, V.; Huang, M.L.H.; Kalinowski, D.S.; Richardson, D.R. Letter to the Editor: Analysis of the Interaction of Dp44mT with Human Serum Albumin and Calf Thymus DNA Using Molecular Docking and Spectroscopic Techniques and. Int. J. Mol. Sci. 2016, 17, 1916. PMID:27854349

  2. Spin transition in Gd3N@C80, detected by low-temperature on-chip SQUID technique

    NASA Astrophysics Data System (ADS)

    Chen, L.; Carpenter, E. E.; Hellberg, C. S.; Dorn, H. C.; Shultz, M.; Wernsdorfer, W.; Chiorescu, I.

    2011-04-01

    We present a magnetic study of the Gd3N@C80 molecule, consisting of a Gd-trimer via a nitrogen atom, encapsulated in a C80 cage. This molecular system can be an efficient contrast agent for magnetic resonance imaging (MRI) applications. We used a low-temperature technique able to detect small magnetic signals by placing the sample in the vicinity of an on-chip SQUID. The technique implemented at the National High Magnetic Field Laboratory has the particularity of being able to operate in high magnetic fields of up to 7 T. The Gd3N@C80 shows a paramagnetic behavior and we find a spin transition of the Gd3N structure at 1.2 K. We perform quantum mechanical simulations, which indicate that one of the Gd ions changes from a 8S7/2 state (L = 0, S = 7/2) to a 7F6 state (L = S = 3, J = 6), likely due to a charge transfer between the C80 cage and the ion.

  3. Multi-site evaluations of a T2-Relaxation-Under-Spin-Tagging (TRUST) MRI technique to measure brain oxygenation

    PubMed Central

    Liu, Peiying; Dimitrov, Ivan; Andrews, Trevor; Crane, David E.; Dariotis, Jacinda K.; Desmond, John; Dumas, Julie; Gilbert, Guillaume; Kumar, Anand; Maclntosh, Bradley J.; Tucholka, Alan; Yang, Shaolin; Xiao, Guanghua; Lu, Hanzhang

    2015-01-01

    Purpose Venous oxygenation (Yv) is an important index of brain physiology and may be indicative of brain diseases. A T2-relaxation-under-spin-tagging (TRUST) MRI technique was recently developed to measure Yv. A multi-site evaluation of this technique would be an important step toward broader availability and potential clinical utilizations of Yv measures. Methods TRUST MRI was performed on a total of 250 healthy subjects, with 125 from the developer’s site and 25 each from five other sites. All sites were equipped with a 3T MRI of the same vendor. The estimated Yv and the standard error of the estimation, εYv, were compared across sites. Results The averaged Yv and εYv across six sites were 61.1±1.4% and 1.3±0.2%, respectively. Multivariate regression analysis showed that the estimated Yv was dependent on age (p=0.009), but not on performance site. In contrast, the standard error of Yv estimation was site-dependent (p=0.024), but was all less than 1.5%. Further analysis revealed that εYv was positively associated with the amount of subject motion (p<0.001) but negatively associated with blood signal intensity (p<0.001). Conclusion This work suggests that TRUST MRI can yield equivalent results of Yv estimation across different sites. PMID:25845468

  4. Study of hydrogen-bonding, vibrational dynamics and structure-activity relationship of genistein using spectroscopic techniques coupled with DFT

    NASA Astrophysics Data System (ADS)

    Singh, Harshita; Singh, Swapnil; Srivastava, Anubha; Tandon, Poonam; Bharti, Purnima; Kumar, Sudhir; Dev, Kapil; Maurya, Rakesh

    2017-02-01

    The conformational and hydrogen bonding studies of genistein have been performed by combined spectroscopic and quantum chemical approach. The vibrational spectra (FT-IR and FT-Raman), UV-visible and 1H and 13C NMR absorption spectra of genistein have been recorded and examined. The vibrational wavenumbers of optimized geometry and total energy for isolated molecule and hydrogen-bonded dimers of genistein have been determined using the quantum chemical calculation (DFT/B3LYP) with extended 6-311++G (d,p) basis set. The vibrational assignments for the observed FT-IR and FT-Raman spectra of genistein are provided by calculations on monomer and hydrogen-bonded dimer. The quantum theory of atoms in molecules (QTAIM) is used for investigating the nature and strength of hydrogen-bonds. UV-visible spectrum of the genistein was recorded in methanol solvent and the electronic properties were calculated by using time-dependent density functional theory (TD-DFT). The computed HOMO and LUMO energies predicted the type of transition as π → π*. The 1H and 13C NMR signals of the genistein were computed by the Gauge including atomic orbital (GIAO) approach. Natural bond orbital (NBO) analysis predicted the stability of molecules due to charge delocalization and hyper conjugative interactions. NBO analysis shows that there is an Osbnd H⋯O inter and intramolecular hydrogen bond, and π → π* transition in the monomer and dimer, which is consistent with the conclusion obtained by the investigation of molecular structure and assignment of UV-visible spectra.

  5. Derivatives of pyrazinecarboxylic acid: 1H, 13C and 15N NMR spectroscopic investigations.

    PubMed

    Holzer, Wolfgang; Eller, Gernot A; Datterl, Barbara; Habicht, Daniela

    2009-07-01

    NMR spectroscopic studies are undertaken with derivatives of 2-pyrazinecarboxylic acid. Complete and unambiguous assignment of chemical shifts ((1)H, (13)C, (15)N) and coupling constants ((1)H,(1)H; (13)C,(1)H; (15)N,(1)H) is achieved by combined application of various 1D and 2D NMR spectroscopic techniques. Unequivocal mapping of (13)C,(1)H spin coupling constants is accomplished by 2D (delta,J) long-range INEPT spectra with selective excitation. Phenomena such as the tautomerism of 3-hydroxy-2-pyrazinecarboxylic acid are discussed.

  6. Multidisciplinary approach for the study of an Egyptian coffin (late 22nd/early 25th dynasty): combining imaging and spectroscopic techniques.

    PubMed

    Bracci, S; Caruso, O; Galeotti, M; Iannaccone, R; Magrini, D; Picchi, D; Pinna, D; Porcinai, S

    2015-06-15

    This paper demonstrates that an educated methodology based on both non-invasive and micro invasive techniques in a two-step approach is a powerful tool to characterize the materials and stratigraphies of an Egyptian coffin, which was restored several times. This coffin, belonging to a certain Mesiset, is now located at the Museo Civico Archeologico of Bologna (inventory number MCABo EG 1963). Scholars attributed it to the late 22nd/early 25th dynasty by stylistic comparison. The first step of the diagnostic approach applied imaging techniques on the whole surface in order to select measurements spots and to unveil both original and restored areas. Images and close microscopic examination of the polychrome surface allowed selecting representative areas to be investigated in situ by portable spectroscopic techniques: X-ray Fluorescence (XRF), Fiber Optic Reflectance Spectroscopy (FORS) and Fourier Transform Infrared spectroscopy (FTIR). After the analysis of the results coming from the first step, very few selected samples were taken to clarify the stratigraphy of the polychrome layers. The first step, based on the combination of imaging and spectroscopic techniques in a totally non-invasive modality, is quite unique in the literature on Egyptian coffins and enabled us to reveal many differences in the ground layer's composition and to identify a remarkable number of pigments in the original and restored areas. This work offered also a chance to check the limitations of the non-invasive approach applied on a complex case, namely the right localization of different materials in the stratigraphy and the identification of binding media. Indeed, to dissolve any remaining doubts on superimposed layers belonging to different interventions, it was necessary to sample few micro-fragments in some selected areas and analyze them prepared as cross-sections. The original ground layer is made of calcite, while the restored areas show the presence of either a mixture of calcite

  7. Multidisciplinary approach for the study of an Egyptian coffin (late 22nd/early 25th dynasty): Combining imaging and spectroscopic techniques

    NASA Astrophysics Data System (ADS)

    Bracci, S.; Caruso, O.; Galeotti, M.; Iannaccone, R.; Magrini, D.; Picchi, D.; Pinna, D.; Porcinai, S.

    2015-06-01

    This paper demonstrates that an educated methodology based on both non-invasive and micro invasive techniques in a two-step approach is a powerful tool to characterize the materials and stratigraphies of an Egyptian coffin, which was restored several times. This coffin, belonging to a certain Mesiset, is now located at the Museo Civico Archeologico of Bologna (inventory number MCABo EG 1963). Scholars attributed it to the late 22nd/early 25th dynasty by stylistic comparison. The first step of the diagnostic approach applied imaging techniques on the whole surface in order to select measurements spots and to unveil both original and restored areas. Images and close microscopic examination of the polychrome surface allowed selecting representative areas to be investigated in situ by portable spectroscopic techniques: X-ray Fluorescence (XRF), Fiber Optic Reflectance Spectroscopy (FORS) and Fourier Transform Infrared spectroscopy (FTIR). After the analysis of the results coming from the first step, very few selected samples were taken to clarify the stratigraphy of the polychrome layers. The first step, based on the combination of imaging and spectroscopic techniques in a totally non-invasive modality, is quite unique in the literature on Egyptian coffins and enabled us to reveal many differences in the ground layer's composition and to identify a remarkable number of pigments in the original and restored areas. This work offered also a chance to check the limitations of the non-invasive approach applied on a complex case, namely the right localization of different materials in the stratigraphy and the identification of binding media. Indeed, to dissolve any remaining doubts on superimposed layers belonging to different interventions, it was necessary to sample few micro-fragments in some selected areas and analyze them prepared as cross-sections. The original ground layer is made of calcite, while the restored areas show the presence of either a mixture of calcite

  8. Determination of Two-Photon Absorption Cross-Section of Noble Gases for Calibration of Laser Spectroscopic Techniques

    SciTech Connect

    Rosa, M. I. de la; Perez, C.; Gruetzmacher, K.; Fuentes, L. M.

    2008-10-22

    The objective of our work is to apply two-photon polarization spectroscopy as a new calibration method for the determination of two-photon excitation cross-sections of noble gases, like Xe and Kr, which are commonly used for calibrations of MP-LIF techniques in other laboratories.

  9. RHIC SPIN FLIPPER

    SciTech Connect

    BAI,M.; ROSER, T.

    2007-06-25

    This paper proposes a new design of spin flipper for RHIC to obtain full spin flip with the spin tune staying at half integer. The traditional technique of using an rf dipole or solenoid as spin flipper to achieve full spin flip in the presence of full Siberian snake requires one to change the snake configuration to move the spin tune away from half integer. This is not practical for an operational high energy polarized proton collider like RHIC where beam lifetime is sensitive to small betatron tune change. The design of the new spin flipper as well as numerical simulations are presented.

  10. Parametrization of the magnetic behavior of the triangular spin ladder chains organically templated: (C2N2H10)[M(HPO3)F3] (M(III) = Fe, Cr, and V). Crystal structure and thermal and spectroscopic properties of the iron(III) phase.

    PubMed

    Fernández-Armas, Sergio; Mesa, José L; Pizarro, José L; Clemente-Juan, Juan Modesto; Coronado, Eugenio; Arriortua, María I; Rojo, Teófilo

    2006-04-17

    A new iron(III) phosphite templated by ethylenediamine has been synthesized using solvothermal conditions under autogenous pressure. The (C2N2H10)[Fe(HPO3)F3] compound has been characterized by single-crystal X-ray diffraction data and spectroscopic and magnetic techniques. The crystal structure is formed by chains extended along the c axis and surrounded by ethylenediammonium cations. A study by diffuse-reflectance spectroscopy has been performed, and the calculated Dq, B, and C parameters for the Fe(III) cations are 1030, 720, and 3080 cm(-1), respectively. The Mössbauer spectrum at room temperature is characteristic of Fe(III) ions. The electron spin resonance (ESR) spectra carried out at different temperatures show isotropic signals with a g value of 2.00(1). The thermal evolution of the intensity of the ESR signals indicates the existence of antiferromagnetic interactions for the Fe(III) phase. The magnetic susceptibility data of the Cr(III) and V(III) compounds show antiferromagnetic couplings. The J-exchange parameters of the Fe(III) and Cr(III) compounds have been calculated by using a model for a triangular spin ladder chain. The values are J1 = -1.63(1) K and J2 = -0.87(2) K with g = 2.02 for the Fe(III) phase and J(1) = -0.56(2) K and J2 = -0.40(2) K with g = 1.99 for the Cr(III) compound. In the case of the V(III) phase, the fit has been performed considering a linear chain with the magnetic parameters D = 2.5 cm(-1) and J = -1.15(1) K.

  11. Comprehensive analysis of TEM methods for LiFePO4/FePO4 phase mapping: spectroscopic techniques (EFTEM, STEM-EELS) and STEM diffraction techniques (ACOM-TEM).

    PubMed

    Mu, X; Kobler, A; Wang, D; Chakravadhanula, V S K; Schlabach, S; Szabó, D V; Norby, P; Kübel, C

    2016-11-01

    Transmission electron microscopy (TEM) has been used intensively in investigating battery materials, e.g. to obtain phase maps of partially (dis)charged (lithium) iron phosphate (LFP/FP), which is one of the most promising cathode material for next generation lithium ion (Li-ion) batteries. Due to the weak interaction between Li atoms and fast electrons, mapping of the Li distribution is not straightforward. In this work, we revisited the issue of TEM measurements of Li distribution maps for LFP/FP. Different TEM techniques, including spectroscopic techniques (energy filtered (EF)TEM in the energy range from low-loss to core-loss) and a STEM diffraction technique (automated crystal orientation mapping (ACOM)), were applied to map the lithiation of the same location in the same sample. This enabled a direct comparison of the results. The maps obtained by all methods showed excellent agreement with each other. Because of the strong difference in the imaging mechanisms, it proves the reliability of both the spectroscopic and STEM diffraction phase mapping. A comprehensive comparison of all methods is given in terms of information content, dose level, acquisition time and signal quality. The latter three are crucial for the design of in-situ experiments with beam sensitive Li-ion battery materials. Furthermore, we demonstrated the power of STEM diffraction (ACOM-STEM) providing additional crystallographic information, which can be analyzed to gain a deeper understanding of the LFP/FP interface properties such as statistical information on phase boundary orientation and misorientation between domains.

  12. On-line preferential solvation studies of polymers by coupled chromatographic-Fourier transform infrared spectroscopic flow-cell technique.

    PubMed

    Malanin, M; Eichhorn, K-J; Lederer, A; Treppe, P; Adam, G; Fischer, D; Voigt, D

    2009-12-18

    Qualitative and quantitative comparison between liquid chromatography (LC) and LC coupled with Fourier transform infrared spectroscopy (LC-FTIR) to evaluate preferential solvation phenomenon of polymers in a mixed solvent has been performed. These studies show that LC-FTIR technique leads to detailed structural information without the requirement for determination of additional parameters for quantitative analysis except calibration. Appropriate experimental conditions for preferential solvation study have been established by variation of polymer concentration, molar mass and eluent content.

  13. Electrical and optical properties of p-type codoped ZnO thin films prepared by spin coating technique

    NASA Astrophysics Data System (ADS)

    Pathak, Trilok Kumar; Kumar, Vinod; Swart, H. C.; Purohit, L. P.

    2016-03-01

    Undoped, doped and codoped ZnO thin films were synthesized on glass substrates using a spin coating technique. Zinc acetate dihydrate, ammonium acetate and aluminum nitrate were used as precursor for zinc, nitrogen and aluminum, respectively. X-ray diffraction shows that the thin films have a hexagonal wurtzite structure for the undoped, doped and co-doped ZnO. The transmittance of the films was above 80% and the band gap of the film varied from 3.20 eV to 3.24 eV for undoped and doped ZnO. An energy band diagram to describe the photoluminescence from the thin films was also constructed. This diagram includes the various defect levels and possible quasi-Fermi levels. A minimum resistivity of 0.0834 Ω-cm was obtained for the N and Al codoped ZnO thin films with p-type carrier conductivity. These ZnO films can be used as a window layer in solar cells and in UV lasers.

  14. Concentration influence on structural and optical properties of SnO2 thin films synthesized by the spin coating technique.

    NASA Astrophysics Data System (ADS)

    Belhamri, Soumia; Hamdadou, Nasr-Eddine

    2016-10-01

    Tin dioxide is an n-type semiconductor, with wide band gap 3.6 eV and special properties such as high optical transmission in the visible range, the infrared reflection and chemical stability. The objective of our work is to study the effect of solution concentration on the properties of SnO2 thin films, which were deposited on glass substrate by sol-gel spin coating technique and characterized by X-ray diffraction, UV-visible spectroscopy after annealing for one hour at 500°C. X ray diffraction spectra (XRD) showed that the films deposited at different concentrations (0.7 mol/l, 1 mol/l, 1.5 mol/l) are polycrystalline with a rutile type tetragonal. The grains have two preferred orientations along the directions (110) and (101) corresponding to 2θ = 26,744° and 34,113° respectively. We have also noted that the grain size change between 20 and 40 nm. The peak of diffraction becomes less intense when the solution concentration is more than 0.7 mol / l. The opticall transmittance of the films in the visible spectrum was in the range of 59 - 44%.

  15. Evaluation of structure-reactivity descriptors and biological activity spectra of 4-(6-methoxy-2-naphthyl)-2-butanone using spectroscopic techniques

    NASA Astrophysics Data System (ADS)

    Agrawal, Megha; Deval, Vipin; Gupta, Archana; Sangala, Bagvanth Reddy; Prabhu, S. S.

    2016-10-01

    The structure and several spectroscopic features along with reactivity parameters of the compound 4-(6-methoxy-2-naphthyl)-2-butanone (Nabumetone) have been studied using experimental techniques and tools derived from quantum chemical calculations. Structure optimization is followed by force field calculations based on density functional theory (DFT) at the B3LYP/6-311++G(d,p) level of theory. The vibrational spectra have been interpreted with the aid of normal coordinate analysis. UV-visible spectrum and the effect of solvent have been discussed. The electronic properties such as HOMO and LUMO energies have been determined by TD-DFT approach. In order to understand various aspects of pharmacological sciences several new chemical reactivity descriptors - chemical potential, global hardness and electrophilicity have been evaluated. Local reactivity descriptors - Fukui functions and local softnesses have also been calculated to find out the reactive sites within molecule. Aqueous solubility and lipophilicity have been calculated which are crucial for estimating transport properties of organic molecules in drug development. Estimation of biological effects, toxic/side effects has been made on the basis of prediction of activity spectra for substances (PASS) prediction results and their analysis by Pharma Expert software. Using the THz-TDS technique, the frequency-dependent absorptions of NBM have been measured in the frequency range up to 3 THz.

  16. In vivo optical analysis of pancreatic cancer tissue in living model mice using fluorescence and Raman spectroscopic techniques

    NASA Astrophysics Data System (ADS)

    Suzuki, Toshiaki; Hattori, Yusuke; Katagiri, Takashi; Mitsuoka, Hiroki; Sato, Ken-ichi; Asakura, Toru; Shimosegawa, Toru; Sato, Hidetoshi

    2009-02-01

    Living pancreatic cancer tissues grown subcutaneously in nude mice are studied by in vivo Raman spectroscopy and autofluorescence imaging. Comparing the same point spectra of alive pancreatic cancer tissue to that of the dead tissue, it is found that they are different each other. The results suggest that the spectral changes reflect the protein conformational changes in the tumor tissue with death of the host animal. From the result of autofluorescence study, in vivo autofluorescence imaging has potential as a method to assign the histological elements of the pancreatic cancer tissue without any staining. These results strongly suggest that combination of these techniques is very important to study biological tissue.

  17. Evaluating the abnormal ossification in tibiotarsi of developing chick embryos exposed to 1.0ppm doses of platinum group metals by spectroscopic techniques.

    PubMed

    Stahler, Adam C; Monahan, Jennifer L; Dagher, Jessica M; Baker, Joshua D; Markopoulos, Marjorie M; Iragena, Diane B; NeJame, Britney M; Slaughter, Robert; Felker, Daniel; Burggraf, Larry W; Isaac, Leon A C; Grossie, David; Gagnon, Zofia E; Sizemore, Ioana E Pavel

    2013-04-01

    Platinum group metals (PGMs), i.e., palladium (Pd), platinum (Pt) and rhodium (Rh), are found at pollutant levels in the environment and are known to accumulate in plant and animal tissues. However, little is known about PGM toxicity. Our previous studies showed that chick embryos exposed to PGM concentrations of 1mL of 5.0ppm (LD50) and higher exhibited severe skeletal deformities. This work hypothesized that 1.0ppm doses of PGMs will negatively impact the mineralization process in tibiotarsi. One milliliter of 1.0ppm of Pd(II), Pt(IV), Rh(III) aqueous salt solutions and a PGM-mixture were injected into the air sac on the 7th and 14th day of incubation. Control groups with no-injection and vehicle injections were included. On the 20th day, embryos were sacrificed to analyze the PGM effects on tibiotarsi using four spectroscopic techniques. 1) Micro-Raman imaging: Hyperspectral Raman data were collected on paraffin embedded cross-sections of tibiotarsi, and processed using in-house-written MATLAB codes. Micro-Raman univariate images that were created from the ν1(PO4(3-)) integrated areas revealed anomalous mineral inclusions within the bone marrow for the PGM-mixture treatment. The age of the mineral crystals (ν(CO3(2-))/ν1(PO4(3-))) was statistically lower for all treatments when compared to controls (p≤0.05). 2) FAAS: The percent calcium content of the chemically digested tibiotarsi in the Pd and Pt groups changed by ~45% with respect to the no-injection control (16.1±0.2%). 3) Micro-XRF imaging: Abnormal calcium and phosphorus inclusions were found within the inner longitudinal sections of tibiotarsi for the PGM-mixture treatment. A clear increase in the mineral content was observed for the outer sections of the Pd treatment. 4) ICP-OES: PGM concentrations in tibiotarsi were undetectable (<5ppb). The spectroscopic techniques gave corroborating results, confirmed the hypothesis, and explained the observed pathological (skeletal developmental abnormalities

  18. Observational and laboratory studies of optical properties of black and brown carbon particles in the atmosphere using spectroscopic techniques

    NASA Astrophysics Data System (ADS)

    Nakayama, Tomoki; Matsumi, Yutaka

    2015-04-01

    Light absorption and scattering by aerosols are as an important contributor to radiation balance in the atmosphere. Black carbon (BC) is considered to be the most potent light absorbing material in the visible region of the spectrum, although light absorbing organic carbon (brown carbon or BrC) and mineral dust may also act as sources of significant absorption, especially in the ultraviolet (UV) and shorter visible wavelength regions. The optical properties of such particles depend on wavelength, particle size and shape, morphology, coating, and complex refractive index (or chemical composition), and therefore accurate in situ measurements of the wavelength dependence of the optical properties of particles are needed. Recently, cavity ring-down spectroscopy (CRDS) and photoacoustic spectroscopy (PAS) have been used for the direct measurements of extinction and absorption coefficients of particles suspended in air. We have applied these techniques to the observational studies of optical properties of BC and BrC in an urban site in Japan and to the laboratory studies of optical properties of secondary organic aerosols (SOAs) generated from a variety of biogenic and anthropogenic volatile organic compounds and those of diesel exhaust particles (DEPs). In the presentation, the basic principles of these techniques and the results obtained in our studies and in the recent literatures will be overviewed. References Guo, X. et al., Measurement of the light absorbing properties of diesel exhaust particles using a three-wavelength photoacoustic spectrometer, Atmos. Environ., 94, 428-437 (2014). Nakayama, T. et al., Measurements of aerosol optical properties in central Tokyo during summertime using cavity ring-down spectroscopy: Comparison with conventional techniques, Atmos. Environ., 44, 3034-3042 (2010). Nakayama, T. et al., Laboratory studies on optical properties of secondary organic aerosols generated during the photooxidation of toluene and the ozonolysis of alpha

  19. Spectroscopic Evidence for Strong Quantum Spin Fluctuations with Itinerant Character in YFe2Ge2

    SciTech Connect

    Sirica, N.; Bondino, F.; Nappini, S.; Piz, I.; Poudel, L.; Christianson, Andrew D.; Mandrus, D.; Singh, David J; Mannella, Norman

    2015-03-04

    We report x-ray absorption and photoemission spectroscopy of the electronic structure in the normal state of metallic YFe2Ge2. The data reveal evidence for large fluctuating spin moments on the Fe sites, as indicated by exchange multiplets appearing in the Fe 3s core-level photoemission spectra, even though the compound does not show magnetic order. The magnitude of the multiplet splitting is comparable to that observed in the normal state of the Fe-pnictide superconductors. This shows a connection between YFe2Ge2 and the Fe-based superconductors even though it contains neither pnictogens nor chalcogens. Finally, the implication is that the chemical range of compounds showing at least one of the characteristic magnetic signatures of the Fe-based superconductors is broader than previously thought.

  20. A new approach for the modelling of chestnut wood photo-degradation monitored by different spectroscopic techniques.

    PubMed

    Bonifazi, G; Calienno, L; Capobianco, G; Monaco, A Lo; Pelosi, C; Picchio, R; Serranti, S

    2016-01-15

    The aim of this work is to study the colour and chemical modifications of the surfaces in chestnut wood samples as a consequence of irradiating in a controlled environment. The changes were investigated by a new analytical approach by combining traditional techniques such as reflectance spectrophotometry in the visible range and Fourier transform infrared spectroscopy with new hyperspectral imaging, in order to obtain forecast models to describe the phenomenon. The statistical elaboration of the experimental data allowed to validate the measurements and to obtain models enabling to relate the investigated parameters; the elaboration of the hyperspectral images by chemometric methods allowed for studying the changes in the reflectance spectra. A result of great importance is the possibility to correlate the oxidation of wood chemical components with the colour change in a totally non-invasive modality. This result is particularly relevant in the field of cultural heritage and in general in the control processes of wooden materials.

  1. Development of synchrotron x-ray micro-spectroscopic techniques and application to problems in low temperature geochemistry. Progress report

    SciTech Connect

    Not Available

    1993-10-01

    The focus of the technical development effort has been the development of apparatus and techniques for the utilization of X-ray Fluorescence (XRF), Extended X-ray Absorption Fine Structure (EXAFS) and X-ray Absorption Near Edge Structure (XANES) spectroscopies in a microprobe mode. The present XRM uses white synchrotron radiation (3 to 30 keV) from a bending magnet for trace element analyses using the x-ray fluorescence technique Two significant improvements to this device have been recently implemented. Focusing Mirror: An 8:1 ellipsoidal mirror was installed in the X26A beamline to focus the incident synchrotron radiation and thereby increase the flux on the sample by about a factor of 30. Incident Beam Monochromator: The monochromator has been successfully installed and commissioned in the X26A beamline upstream of the mirror to permit analyses with focused monochromatic radiation. The monochromator consists of a channel-cut silicon (111) crystal driven by a Klinger stepping motor translator. We have demonstrated the operating range of this instrument is 4 and 20 keV with 0.01 eV steps and produces a beam with a {approximately}10{sup {minus}4} energy bandwidth. The primary purpose of the monochromator is for x-ray absorption spectroscopy (XAS) measurements but it is also used for selective excitation in trace element microanalysis. To date, we have conducted XANES studies on Ti, Cr, Fe, Ce and U, spanning the entire accessible energy range and including both K and L edge spectra. Practical detection limits for microXANES are 10--100 ppM for 100 {mu}m spots.

  2. Precise oxygen and hydrogen isotope determination in nanoliter quantities of speleothem inclusion water by cavity ring-down spectroscopic techniques

    NASA Astrophysics Data System (ADS)

    Uemura, Ryu; Nakamoto, Masashi; Asami, Ryuji; Mishima, Satoru; Gibo, Masakazu; Masaka, Kosuke; Jin-Ping, Chen; Wu, Chung-Che; Chang, Yu-Wei; Shen, Chuan-Chou

    2016-01-01

    Speleothem inclusion-water isotope compositions are a promising new climatic proxy, but their applicability is limited by their low content in water and by analytical challenges. We have developed a precise and accurate isotopic technique that is based on cavity ring-down spectroscopy (CRDS). This method features a newly developed crushing apparatus, a refined sample extraction line, careful evaluation of the water/carbonate adsorption effect. After crushing chipped speleothem in a newly-developed crushing device, released inclusion water is purified and mixed with a limited amount of nitrogen gas in the extraction line for CRDS measurement. We have measured 50-260 nL of inclusion water from 77 to 286 mg of stalagmite deposits sampled from Gyokusen Cave, Okinawa Island, Japan. The small sample size requirement demonstrates that our analytical technique can offer high-resolution inclusion water-based paleoclimate reconstructions. The 1σ reproducibility for different stalagmites ranges from ±0.05 to 0.61‰ for δ18O and ±0.0 to 2.9‰ for δD. The δD vs. δ18O plot for inclusion water from modern stalagmites is consistent with the local meteoric water line. The 1000 ln α values based on calcite and fluid inclusion measurements from decades-old stalagmites are in agreement with the data from present-day farmed calcite experiment. Combination of coeval carbonate and fluid inclusion data suggests that past temperatures at 9-10 thousand years ago (ka) and 26 ka were 3.4 ± 0.7 °C and 8.2 ± 2.4 °C colder than at present, respectively.

  3. Use of radiocarbon and spectroscopic analyses to characterise soil organic matter pools isolated using different fractionation techniques.

    NASA Astrophysics Data System (ADS)

    Miller, Gemma; Cloy, Joanna; Garnett, Mark; Sohi, Saran; Rees, Robert; Griffiths, Bryan

    2015-04-01

    Experimental division of soil organic matter (SOM) into functional pools has the potential to improve soil C modelling. Soil physical fractionation techniques seek to quantify these pools, however the fractions isolated vary in number, size, ecological role and composition. The use of different techniques to quantify soil C fractions in different studies presents a question - do similar fractions isolated by different methods fit the same conceptual definition? This study examined a sandy loam from the south-west of Scotland, sampled in summer, which had been under grassland management for at least 20 years. We compared average 14C ages of SOM fractions isolated using three published and frequently applied physical fractionation methods (1) a density separation technique isolating three fractions - free light (FLF) < 1.8 cm 3, intra-aggregate light (IALF) < 1.8 cm-3 after aggregate disruption, and organo-mineral (O-min) > 1.8 g cm 3 (Sohi et al, 2001); (2) a combined physical and chemical separation isolating five fractions: sand and aggregates (S+A) > 63 µm and > 1.8 g cm-3, particulate organic matter (POM) > 63 µm and < 1.8 g cm 3, silt and clay (s+c) < 63 but > 45 µm, residual organic carbon (rSOC) the residue left after s+c is oxidised with NaOCl, and dissolved organic carbon (DOC) < 45 µm (Zimmermann et al, 2007); and (3) a hot water extraction method isolating two fractions: water soluble C (WSC) at 20 °C and hot water extractable C (HWEC) at 80 °C (Ghani et al, 2003). The fractions from Method 1 had the most distinct average 14C ages with O-min, FLF and IALF assessed as 206, 1965 and 6172 years before present (BP) respectively. The fractions from Method 2 fell into two age groups, < ~1000 years BP for s+c, rSOC and S+A and > 4000 years BP for DOC and POM. Both Method 3 fractions were dominated by modern C. The average 14C ages of FLF, IALF, DOC and POM were surprisingly higher than the mineral bound fractions, although they made up a relatively small

  4. Using terahertz time-domain spectroscopical technique to monitor cocrystal formation between piracetam and 2,5-dihydroxybenzoic acid

    NASA Astrophysics Data System (ADS)

    Du, Yong; Xia, Yi; Zhang, Huili; Hong, Zhi

    2013-07-01

    Far-infrared vibrational absorption of cocrystal formation between 2,5-dihydroxybenzoic acid (2,5-DHBA) and piracetam compounds under solvent evaporation and grinding methods have been investigated using terahertz time-domain spectroscopy (THz-TDS) at room temperature. The experimental results show large difference among absorption spectra of the formed cocrystals and the involved individual parent molecules in 0.20-1.50 THz region, which probably originated from the intra-molecular and inter-molecular hydrogen bonds due to the presence of two hydroxyl groups in 2,5-DHBA and amide moieties in piracetam compound. The THz absorption spectra of two formed cocrystals with different methods are almost identical. With grinding method, the reaction process can be monitored directly from both time-domain and frequency-domain spectra using THz-TDS technique. The results indicate that THz-TDS technology can absolutely offer us a high potential method to identify and characterize the formed cocrystals, and also provide the rich information about their reaction dynamic process involving two or more molecular crystals in situ to better know the corresponding reaction mechanism in pharmaceutical fields.

  5. Using terahertz time-domain spectroscopical technique to monitor cocrystal formation between piracetam and 2,5-dihydroxybenzoic acid.

    PubMed

    Du, Yong; Xia, Yi; Zhang, Huili; Hong, Zhi

    2013-07-01

    Far-infrared vibrational absorption of cocrystal formation between 2,5-dihydroxybenzoic acid (2,5-DHBA) and piracetam compounds under solvent evaporation and grinding methods have been investigated using terahertz time-domain spectroscopy (THz-TDS) at room temperature. The experimental results show large difference among absorption spectra of the formed cocrystals and the involved individual parent molecules in 0.20-1.50 THz region, which probably originated from the intra-molecular and inter-molecular hydrogen bonds due to the presence of two hydroxyl groups in 2,5-DHBA and amide moieties in piracetam compound. The THz absorption spectra of two formed cocrystals with different methods are almost identical. With grinding method, the reaction process can be monitored directly from both time-domain and frequency-domain spectra using THz-TDS technique. The results indicate that THz-TDS technology can absolutely offer us a high potential method to identify and characterize the formed cocrystals, and also provide the rich information about their reaction dynamic process involving two or more molecular crystals in situ to better know the corresponding reaction mechanism in pharmaceutical fields.

  6. X-ray spectroscopic technique for energetic electron transport studies in short-pulse laser/plasma interactions

    SciTech Connect

    Tutt, T.E.

    1994-12-01

    When a solid target is irradiated by a laser beam, the material is locally heated to a high temperature and a plasma forms. The interaction of the laser with plasma can produce energetic electrons. By observing the behavior of these {open_quotes}hot{close_quotes} electrons, we hope to obtain a better understanding of Laser/Plasma Interactions. In this work we employ a layered-fluorescer technique to study the transport, and therefore the energetics, of the electrons. The plasma forms on a thin foil of metallic Pd which is bonded to thin layer of metallic Sn. Electrons formed from the plasma penetrate first the Pd and then the Sn. In both layers the energetic electrons promote inner (K) shell ionization of the metallic atoms which leads to the emission of characteristic K{sub {alpha}} x-rays of the fluorescers. By recording the x-ray spectrum emitted by the two foils, we can estimate the energy-dependent range of the electrons and their numbers.

  7. Study on the interaction of the epilepsy drug, zonisamide with human serum albumin (HSA) by spectroscopic and molecular docking techniques

    NASA Astrophysics Data System (ADS)

    Shahabadi, Nahid; Khorshidi, Aref; Moghadam, Neda Hossinpour

    2013-10-01

    In the present investigation, an attempt has been made to study the interaction of zonisamide (ZNS) with the transport protein, human serum albumin (HSA) employing UV-Vis, fluorometric, circular dichroism (CD) and molecular docking techniques. The results indicated that binding of ZNS to HSA caused strong fluorescence quenching of HSA through static quenching mechanism, hydrogen bonds and van der Waals contacts are the major forces in the stability of protein ZNS complex and the process of the binding of ZNS with HSA was driven by enthalpy (ΔH = -193.442 kJ mol-1). The results of CD and UV-Vis spectroscopy showed that the binding of this drug to HSA induced conformational changes in HSA. Furthermore, the study of molecular docking also indicated that zonisamide could strongly bind to the site I (subdomain IIA) of HSA mainly by hydrophobic interaction and there were hydrogen bond interactions between this drug and HSA, also known as the warfarin binding site.

  8. [IR/UV spectroscopic analysis of gangliosides and their microstructures of polymeric aggregates observed by AFM technique].

    PubMed

    Wang, Hai-long; Sun, Run-guang; Zhang, Jing; Hao, Chang-chun

    2009-04-01

    Gangliosides, a kind of acid glycosphingolipid containing sialic acid, plays a very important physiological role in biomembrane as one of the important components of neurocyte membrane. They were extracted from bovine brain by the Folch method and purified by silica gel and DEAE-Sephadex A-25 column chromatograph. Their molecular functional groups and microstructures of polymeric aggregates were studied by infrared spectrum (IR), ultraviolet spectrum (UV) and atomic force microscope (AFM). The experimental results indicate that: 55.2 mg of Gls from 100 g of wet bovine brain had a certain purity, 62.84%. And their UV absorption spectra appeared at 195 nm, near to the results reported by other peoples. Compared with the IR spectra of sialic acid, the experimental results showed that the structures of the products had the units of sialic acid. In order to investigate the aggregate structures of ganglioside. AFM technique was applied in water, and the results showed that gangliosides can form spherical or ellipsoidal structures in water. It was determined that the size of polymeric aggregates of gangliosides varies between 55 and 380 nm, the average size is (148.9+/-66.7) nm; the height is between 1.0 and 5.0 nm, and the average height is (3.25+/-1.01) nm. The experimental results provide a theoretical and experimental basis for investigating biological activity and the exploitation and utilization of neural drugs.

  9. Spin superfluidity and coherent spin precession

    NASA Astrophysics Data System (ADS)

    Bunkov, Yuriy M.

    2009-04-01

    The spontaneous phase coherent precession of the magnetization in superfluid 3He-B was discovered experimentally in 1984 at the Institute for Physical Problems, Moscow by Borovik-Romanov, Bunkov, Dmitriev and Mukharsky and simultaneously explained theoretically by Fomin (Institut Landau, Moscow). Its formation is a direct manifestation of spin superfluidity. The latter is the magnetic counterpart of mass superfluidity and superconductivity. It is also an example of the Bose-Einstein condensation of spin-wave excitations (magnons). The coherent spin precession opened the way for investigations of spin supercurrent magnetization transport and other related phenomena, such as spin-current Josephson effect, process of phase slippage at a critical value of spin supercurrent, spin-current vortices, non-topological solitons (analogous to Q-balls in high energy physics) etc. New measuring techniques based on coherent spin precession made the investigation of mass counterflow and mass vortices possible owing to the spin-mass interaction. New phenomena were observed: mass-spin vortices, the Goldstone mode of the mass vortex with non-axisymmetric core, superfluid density anisotropy etc. Different types of coherent spin precession were later found in superfluid 3He-A and 3He-B confined in anisotropic aerogel, in the states with counterflow and in 3He with reduced magnetization. Finally, spin superfluidity investigations developed the basis for a modern investigation of electron spin supercurrent and spintronics.

  10. Mass and Spin Measurement Techniques (for the Large Hadron Collider):. Lectures Given at TASI 2011, Boulder, Colorado

    NASA Astrophysics Data System (ADS)

    Lester, Christopher G.

    2013-12-01

    For TASI 2011, I was asked to give a series of lectures on "Mass and Spin Measurement Techniques" with relevance to the Large Hadron Collider. This document provides a written record of those lectures - or more precisely of what I said while giving the lectures - warts and all. It is provided as my contribution to the proceedings primarily for the benefit of those who heard the lectures first hand and may wish to refer back to them. What it is not is a scientific paper or a teaching resource. Though lecture slides may be prepared in advance, what is actually said in a lecture is usually extemporaneous, may be partial, can be influenced by audience reaction, and may not even make sense without a visual record of the concomitant gesticulations of the lecturer. More worryingly, some of the statements made may be down-right false, if the lecturer's tongue is in a twist. Accordingly, these proceedings are provided without warranty of any kind - not least in respect of accuracy or impartiality. The lectures were intended to engage the audience and get them thinking about a number of topics that they had not seen before. They were not expected to be the sort of sombre or well-balanced overview of the field that one might hope to achive in a review. These proceedings are provided to jog the memory of those who saw the lectures first hand, and for little other purpose. Footnotes, where they appear, indicate text/thoughts I have added during the editing process that were not voiced during the lectures themselves. Copies of the lecture slides are inserted at approximately the locations they would have become visible in the lectures.

  11. Studying Iron Mineralogy to Understand Redox Conditions in the Mesoproterozoic Belt Basin, USA Using Complementary Microscopic, Spectroscopic, and Magnetic Techniques

    NASA Astrophysics Data System (ADS)

    Slotznick, S. P.; Webb, S.; Kirschvink, J. L.; Fischer, W. W.

    2015-12-01

    Observations of iron chemistry and mineralogy over time provide a valuable tool for studying paleoenvironments, but questions still remain as to the redox character of Proterozoic basins after the rise of oxygen. To evaluate the mechanisms of iron mineralization in Proterozoic samples, we developed an approach that pairs the microscale textural techniques of light microscopy, magnetic scanning microscopy, and (synchrotron-based) microprobe x-ray spectroscopy with sensitive bulk rock magnetic experiments. Samples were collected from stratigraphic sections across the ~1.4 Ga lower Belt Group, Belt Supergroup, MT and ID, USA with a focus on excellently preserved sedimentary rocks, but also including those altered by a variety of diagenetic, metamorphic, and metasomatic events. Results show that even in the best-preserved parts of the Belt Basin, late diagenetic and/or metasomatic fluids affected (in some cases very mildly) the primary iron phases as evidenced by prevalent post-depositional alterations such as rare base metal sulfides. In more heavily altered rocks, the appearance of pyrrhotite and other minerals signaled transformations in iron mineralogy through metamorphism and metasomatism. Despite these secondary phases crystallizing in an open fluid-rich system, primary records of redox chemistry were preserved in the recrystallized early diagenetic framboidal pyrite and (sub)micron-sized detrital magnetite grains. Detrital magnetite is not the most abundant iron-bearing phase in any of the samples (typically <0.01 wt%), but is widely observed in both proximal and deeper basin facies, illustrating an important detrital flux of iron to the basin and a highly reactive iron source for early diagenetic pyrite. Based on our analyses, we interpret the shallow waters of the Belt Basin to be oxic with sulfidic pore fluids and deeper waters in parts of the basin as likely euxinic, consistent with the results of some bulk geochemical proxies. This redox reconstruction also

  12. An assessment of contemporary atomic spectroscopic techniques for the determination of lead in blood and urine matrices

    NASA Astrophysics Data System (ADS)

    Parsons, Patrick J.; Geraghty, Ciaran; Verostek, Mary Frances

    2001-09-01

    The preparation and validation of a number of clinical reference materials for the determination of lead in blood and urine is described. Four candidate blood lead reference materials (Lots, 047-050), and four candidate urine lead reference materials (Lots, 034, 035, 037 and 038), containing physiologically-bound lead at clinically relevant concentrations, were circulated to up to 21 selected laboratories specializing in this analysis. Results from two interlaboratory studies were used to establish certified values and uncertainty estimates for these reference materials. These data also provided an assessment of current laboratory techniques for the measurement of lead in blood and urine. For the blood lead measurements, four laboratories used electrothermal atomization AAS, three used anodic stripping voltammetry and one used both ETAAS and ICP-MS. For the urine lead measurements, 11 laboratories used ETAAS (most with Zeeman background correction) and 10 used ICP-MS. Certified blood lead concentrations, ±S.D., ranged from 5.9±0.4 μg/dl (0.28±0.02 μmol/l) to 76.0±2.2 μg/dl (3.67±0.11 μmol/l) and urine lead concentrations ranged from 98±5 μg/l (0.47±0.02 μmol/l) to 641±36 μg/l (3.09±0.17 μmol/l). The highest concentration blood lead material was subjected to multiple analyses using ETAAS over an extended time period. The data indicate that more stringent internal quality control practices are necessary to improve long-term precision. While the certification of blood lead materials was accomplished in a manner consistent with established practices, the urine lead materials proved more troublesome, particularly at concentrations above 600 μg/l (2.90 μmol/l).

  13. Structure and spectroscopic analysis of the graphene monolayer film directly grown on the quartz substrate via the HF-CVD technique

    NASA Astrophysics Data System (ADS)

    Mahmoud, Waleed E.; Al-Hazmi, Farag S.; Al-Ghamdi, A. A.; Shokr, F. S.; Beall, Gary W.; Bronstein, Lyudmila M.

    2016-08-01

    Direct growth of a monolayer graphene film on a quartz substrate by a hot filament chemical vapor deposition technique is reported. The monolayer graphene film prepared was characterized by Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), selected area electron diffraction (SAED), and atomic force microscopy (AFM). The optical properties were studied by spectroscopic elliposmetry. The experimental data were fitted by the Forouhi-Bloomer model to estimate the extinction coefficient and the refractive index of the monolayer graphene film. The refractive index spectrum in the visible region was studied based on the harmonic oscillator model. The lattice dielectric constant, real and imaginary dielectric constants and the ratio of the charge carrier number to the effective mass were determined. The surface and volume energy loss parameters were also found and showed that the value of the surface energy loss is greater than the volume energy loss. The determination of these optical constants will open new avenue for novel applications of graphene films in the field of wave plates, light modulators, ultrahigh-frequency signal processing and LCDs.

  14. Binding site identification of metformin to human serum albumin and glycated human serum albumin by spectroscopic and molecular modeling techniques: a comparison study.

    PubMed

    Rahnama, Elaheh; Mahmoodian-Moghaddam, Maryam; Khorsand-Ahmadi, Sabra; Saberi, Mohammad Reza; Chamani, Jamshidkhan

    2015-01-01

    The interaction between metformin and human serum albumin (HSA), as well as its glycated form (gHSA) was investigated by multiple spectroscopic techniques, zeta potential, and molecular modeling under physiological conditions. The steady state and time-resolved fluorescence data displayed the quenching mechanism of HSA-metformin and gHSA-metformin was static. The binding information, including the binding constants, number of binding sites, effective quenching constant showed that the binding affinity of metformin to HSA was greater than to gHSA which also confirmed by anisotropy measurements. It was determined that metformin had two and one set of binding sites on HSA and gHSA, respectively. Far-UV CD spectra of proteins demonstrated that the α-helical content decreased with increasing metformin concentration. The zeta potential and resonance light scattering (RLS) diagrams provided that lower drug concentration induced metformin aggregation on gHSA surface as compare to HSA. The increase in polarizability was one of the important factors for the enhancement of RLS and the formation of drug/protein complexes. The zeta potential results suggested that both hydrophobic and electrostatic interactions played important roles in the protein-metformin complex formation. Site marker experiments and molecular modeling showed that the metformin bound to subdomain IIIA (Sudlow's site II) on HSA and gHSA.

  15. Studies on the interaction between promethazine and human serum albumin in the presence of flavonoids by spectroscopic and molecular modeling techniques.

    PubMed

    He, Ling-Ling; Wang, Zhi-Xin; Wang, Yong-Xia; Liu, Xian-Ping; Yang, Yan-Jie; Gao, Yan-Ping; Wang, Xin; Liu, Bin; Wang, Xin

    2016-09-01

    Fluorescence, absorption, time-correlated single photon counting (TCSPC), and circular dichroism (CD) spectroscopic techniques as well as molecular modeling methods were used to study the binding characterization of promethazine (PMT) to human serum albumin (HSA) and the influence of flavonoids, rutin and baicalin, on their affinity. The results indicated that the fluorescence quenching mechanism of HSA by PMT is a static quenching due to the formation of complex. The reaction was spontaneous and mainly mediated by hydrogen bonds and hydrophobic interactions. The binding distance between the tryptophan residue of HSA and PMT is less than 8nm, which indicated that the energy transfer from the tryptophan residue of HSA to PMT occurred. The binding site of PMT on HSA was located in sites I and the presence of PMT can cause the conformational changes of HSA. There was the competitive binding to HSA between PMT and flavonoids because of the overlap of binding sites in HSA. The flavonoids could decrease the association constant and increase the binding distance. In addition, their synergistic effect can further change the conformation of HSA. The decrease in the affinities of PMT binding to HSA in the presence of flavonoids may lead to the increase of free drug in blood, which would affect the transportation or disposition of drug and evoke an adverse or toxic effect. Hence, rationalising dosage and diet regimens should be taken into account in clinical application of PMT.

  16. High-Spin Cobalt Hydrides for Catalysis

    SciTech Connect

    Holland, Patrick L.

    2013-08-29

    Organometallic chemists have traditionally used catalysts with strong-field ligands that give low-spin complexes. However, complexes with a weak ligand field have weaker bonds and lower barriers to geometric changes, suggesting that they may lead to more rapid catalytic reactions. Developing our understanding of high-spin complexes requires the use of a broader range of spectroscopic techniques, but has the promise of changing the mechanism and/or selectivity of known catalytic reactions. These changes may enable the more efficient utilization of chemical resources. A special advantage of cobalt and iron catalysts is that the metals are more abundant and cheaper than those currently used for major industrial processes that convert unsaturated organic molecules and biofeedstocks into useful chemicals. This project specifically evaluated the potential of high-spin cobalt complexes for small-molecule reactions for bond rearrangement and cleavage reactions relevant to hydrocarbon transformations. We have learned that many of these reactions proceed through crossing to different spin states: for example, high-spin complexes can flip one electron spin to access a lower-energy reaction pathway for beta-hydride elimination. This reaction enables new, selective olefin isomerization catalysis. The high-spin cobalt complexes also cleave the C-O bond of CO2 and the C-F bonds of fluoroarenes. In each case, the detailed mechanism of the reaction has been determined. Importantly, we have discovered that the cobalt catalysts described here give distinctive selectivities that are better than known catalysts. These selectivities come from a synergy between supporting ligand design and electronic control of the spin-state crossing in the reactions.

  17. Comparison of Y2O3:Bi3+ phosphor thin films fabricated by the spin coating and radio frequency magnetron techniques

    NASA Astrophysics Data System (ADS)

    Jafer, R. M.; Yousif, A.; Kumar, Vinod; Pathak, Trilok Kumar; Purohit, L. P.; Swart, H. C.; Coetsee, E.

    2016-09-01

    The reactive radio-frequency (RF) magnetron sputtering and spin coating fabrication techniques were used to fabricate Y2-xO3:Bix=0.5% phosphor thin films. The two techniques were analysed and compared as part of investigations being done on the application of down-conversion materials for a Si solar cell. The morphology, structural and optical properties of these thin films were investigated. The X-ray diffraction results of the thin films fabricated by both techniques showed cubic structures with different space groups. The optical properties showed different results because the Bi3+ ion is very sensitive towards its environment. The luminescence results for the thin film fabricated by the spin coating technique is very similar to the luminescence observed in the powder form. It showed three obvious emission bands in the blue and green regions centered at about 360, 410 and 495 nm. These emissions were related to the 3P1-1S0 transition of the Bi3+ ion situated in the two different sites of the Y2O3 matrix with I a-3(206) space group. Whereas the thin film fabricated by the radio frequency magnetron technique showed a broad single emission band in the blue region centered at about 416 nm. This was assigned to the 3P1-1S0 transition of the Bi3+ ion situated in one of the Y2O3 matrix's sites with a Fm-3 (225) space group. The spin coating fabrication technique is suggested to be the best technique to fabricate the Y2O3:Bi3+ phosphor thin films.

  18. Diatomic interhalogens - Systematics and implications of spectroscopic interatomic potentials and curve crossings

    NASA Technical Reports Server (NTRS)

    Child, M. S.; Bernstein, R. B.

    1973-01-01

    Spectroscopically derived potential curves for the low-lying excited states of homonuclear and heteronuclear diatomic interhalogens are systematized by the spin-orbit state of their dissociation products. The implications of spectroscopic interatomic potentials and curve crossings are discussed.

  19. Vibrational 13C-cross-polarization/magic angle spinning NMR spectroscopic and thermal characterization of poly(alanine-glycine) as model for silk I Bombyx mori fibroin.

    PubMed

    Monti, Patrizia; Taddei, Paola; Freddi, Giuliano; Ohgo, Kosuke; Asakura, Tetsuo

    2003-01-01

    This study focuses on the conformational characterization of poly(alanine-glycine) II (pAG II) as a model for a Bombyx mori fibroin silk I structure. Raman, IR, and 13C-cross-polarization/magic angle spinning NMR spectra of pAG II are discussed in comparison with those of the crystalline fraction of B. mori silk fibroin (chymotryptic precipitate, Cp) with a silk I (silk I-Cp) structure. The spectral data give evidence that silk I-Cp and the synthetic copolypeptide pAG II have similar conformations. Moreover, the spectral findings reveal that silk I-Cp is more crystalline than pAG II; consequently, the latter contains a larger amount of the random coil conformation. Differential scanning calorimetry measurements confirm this result. N-Deuteration experiments on pAG II allow us to attribute the Raman component at 1320 cm(-1) to the amide III mode of a beta-turn type II conformation, thus confirming the results of those who propose a repeated beta-turn type II structure for silk I. The analysis of the Raman spectra in the nuNH region confirms that the silk I structure is characterized by the presence of different types of H-bonding arrangements, in agreement with the above model.

  20. Differentiation of Salmonella enterica serovars and strains in cultures and food using infrared spectroscopic and microspectroscopic techniques combined with soft independent modeling of class analogy pattern recognition analysis.

    PubMed

    Männig, Annegret; Baldauf, Nathan A; Rodriguez-Romo, Luis A; Yousef, Ahmed E; Rodríguez-Saona, Luis E

    2008-11-01

    Detection of pathogenic microorganisms in food is often a tedious and time-consuming exercise. Developing rapid and cost-effective techniques for identifying pathogens to subspecies is critical for tracking causes of foodborne disease outbreaks. The objective of this study was to develop a method for rapid identification and differentiation of Salmonella serovars and strains within these serovars through isolation on hydrophobic grid membrane filters (HGMFs), examination by infrared (IR) spectroscopy and microspectroscopy, and data analysis by multivariate statistical techniques. Salmonella serovars (Anatum, Enteritidis, Heidelberg, Kentucky, Muenchen, and Typhimurium), most of which were represented by multiple strains, were grown in tryptic soy broth (24 h at 42 degrees C), diluted to 10(2) to 10(3) CFU/ml, and filtered using HGMFs. The membranes were incubated on Miller-Mallinson agar (24 h at 42 degrees C), and typical Salmonella colonies were sonicated in 50% acetonitrile and centrifuged. Resulting pellets were vacuum dried on a ZnSe crystal and analyzed using IR spectroscopy. Alternatively, the membranes containing Salmonella growth were removed from the agar, vacuum dried, and colonies were analyzed directly by IR microspectroscopy. Soft independent modeling of class analogy (SIMCA) models were developed from spectra. The method was validated by analyzing Salmonella-inoculated tomato juice, eggs, milk, and chicken. Salmonella serovars exhibited distinctive and reproducible spectra in the fingerprint region (1,200 to 900 cm(-1)) of the IR spectrum. SIMCA permitted distinguishing Salmonella strains from each other through differences in bacterial lipopolysaccharides and other membrane components. The model correctly predicted Salmonella in foods at serovar (100%) and strain (90%) levels. Isolation of Salmonella on HGMF and selective agar followed by IR spectroscopic analysis resulted in rapid and efficient isolation, identification, and differentiation of

  1. γ -ray decay from neutron-bound and unbound states in 95Mo and a novel technique for spin determination

    NASA Astrophysics Data System (ADS)

    Wiedeking, M.; Krtička, M.; Bernstein, L. A.; Allmond, J. M.; Basunia, M. S.; Bleuel, D. L.; Burke, J. T.; Daub, B. H.; Fallon, P.; Firestone, R. B.; Goldblum, B. L.; Hatarik, R.; Lake, P. T.; Larsen, A. C.; Lee, I.-Y.; Lesher, S. R.; Paschalis, S.; Petri, M.; Phair, L.; Scielzo, N. D.; Volya, A.

    2016-02-01

    The emission of γ rays from neutron-bound and neutron-unbound states in 95Mo, populated in the 94Mo(d ,p ) reaction, has been investigated. Charged particles and γ radiation were detected with arrays of annular silicon and Clover-type high-purity Germanium detectors, respectively. Utilizing p -γ and p -γ -γ coincidences, the 95Mo level scheme was greatly enhanced with 102 new transitions and 43 new states. It agrees well with shell model calculations for excitation energies below ≈2 MeV. From p -γ coincidence data, a new method for the determination of spins of discrete levels is proposed. The method exploits the suppression of high-angular momentum neutron emission from levels with high spins populated in the (d ,p ) reaction above the neutron separation energy. Spins for almost all 95Mo levels below 2 MeV (and for a few levels above) have been determined with this method.

  2. Development of a spectroscopic technique for simultaneous magnetic field, electron density, and temperature measurements in ICF-relevant plasmas (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Dutra, Eric C.; Covington, Aaron M.; Darling, Timothy; Mancini, Roberto C.; Haque, Showera; Angermeier, William A.

    2016-09-01

    Visible spectroscopic techniques are often used in plasma experiments to measure B-field induced Zeeman splitting, electron densities via Stark broadening and temperatures from Doppler broadening. However, when electron densities and temperatures are sufficiently high, the broadening of the Stark and Doppler components can dominate the emission spectra and obscure the Zeeman component. In this research, we are developing a time-resolved multi-axial technique for measuring the Zeeman, Stark, and Doppler broadened line emission of dense magnetized plasmas for Z-pinch and Dense Plasma Focus (DPF) accelerators. The line emission is used to calculate the electron densities, temperatures, and B-fields. In parallel, we are developing a line-shape modeling code that incorporates the broadening effects due to Stark, Doppler, and Zeeman effects for dense magnetized plasma. Experiments conducted at the University of Nevada (Reno) at the Nevada Terawatt Facility (NTF) using the 1 MA Z-pinch (Zebra). The research explored the response of Al III doublet, 4p 2P3/2 to 4s 2S1/2 and 4p 2P1/2 to 4s 2S1/2 transitions. Optical light emitted from the pinch is fiber coupled to high-resolution spectrometers. The dual spectrometers are coupled to two high-speed visible streak cameras to capture time-resolved emission spectra from the experiment. The data reflects emission spectra from 100 ns before the current peak to 100 ns after the current peak, where the current peak is approximately the time at which the pinch occurs. The Al III doublet is used to measure Zeeman, Stark, and Doppler broadened emission. The line emission is then used to calculate the temperature, electron density, and B-fields. The measured quantities are used as initial parameters for the line shape code to simulate emission spectra and compare to experimental results. Future tests are planned to evaluate technique and modeling on other material wire array, gas puff, and DPF platforms. This work was done by National

  3. Spectroscopic Evidence for Covalent Binding of Sulfadiazine to Natural Soils via 1,4-nucleophilic addition (Michael Type Addition) studied by Spin Labeling ESR

    NASA Astrophysics Data System (ADS)

    Aleksandrova, Olga

    2015-04-01

    Among different classes of veterinary pharmaceuticals, Sulfadiazine (SDZ) is widely used in animal husbandry. Its residues were detected in different environmental compartments. However, soil is a hot spot for SDZ as it receives a large portion of excreted compounds through the application of manure during soil fertilization. Ample studies on the fate of SDZ in soils showed that a large portion forms nonextractable residues (NER) along with transformation products and a low mineralization (Mueller et al., 2013). A common observation was an initially fast formation of NER up to 10% of the applied amount promptly after the application of SDZ to soil, and this portion increased up to 50% within a few days (Mueller et al., 2013; Nowak et al., 2011). A common finding for SDZ, as for other sulfonamides, was biphasic kinetics of the formation of NER, which was attributed to the occurrence of two reaction processes: a rapid, often reversible process and a slower, irreversible process (Weber et al., 1996). A single-phase reaction process was also established under anaerobic treatment (Gulkowska et al., 2014). A major focus of this work is to elucidate a reaction mechanism of covalent binding of SDZ to soil that is currently required to estimate a risk of NER formed by SDZ in soils for human health. Taking into account a key role of the amine functional groups of SDZ on its reactivity in soil, nitroxide radicals with the sewed aromatic or aliphatic amines labeled soil samples and then, were investigated by means of ESR spectroscopy. 2,5,5-Trimethyl-2-(3-aminophenyl)pyrrolidin-1-yloxy and 4-amino-2,2,6,6-Tetramethylpiperidin-1-oxyl modeled decomposition products of SDZ with the aromatic and aliphatic amines, respectively. The application of the defined combination of both spin labels (SL) to different soils well simulated a change of a paramagnetic signal of soil organic radicals interacted with SDZ. After their application to soil, SL were found in soil sites characterized

  4. Spectroscopic ellipsometry of Zn(1-x)Cu(x)O thin films based on a modified sol-gel dip-coating technique.

    PubMed

    Al-Khanbashi, Hibah A; Shirbeeny, W; Al-Ghamdi, A A; Bronstein, Lyudmila M; Mahmoud, Waleed E

    2014-01-24

    Nanocrystalline Zn(1-x)Cu(x)O thin films (x=0, 0.01, 0.02, 0.03, 0.04 and 0.05) were synthesized by sol-gel dip-coating technique on a quartz substrate. These films were annealed at 350°C for 2 h. The X-ray diffraction showed a hexagonal crystal structure with high intensity peak for the (002) reflection plane indicating preferential growth along the c-axis of the crystal lattice. The peak position related to the (002) peak was shifted as a result of the copper ion incorporation, confirming the interstitial substitution of the zinc ions by the copper ions. This interstitial substitution leads to a decrease of an average crystallite size and lattice constants and an increase of the micro-strain up to 2 at.% of the copper amount. The surface morphology was explored by scanning electron microscopy which confirmed the homogenous distribution of nanoparticles in the deposited films along the quartz substrates. The energy dispersion X-ray spectroscopy revealed absence of impurities in the as-deposited films. The high resolution electron microscopy and selected area electron diffraction depicted that the films have polycrystalline nature. The film thickness and optical constants of the Zn(1-x)Cu(x)O thin films were estimated by fitting the spectroscopic ellipsometric data (ψ and Δ) using three different models. The refractive index was fitted using harmonic oscillator model from which the oscillator and the dispersive energies were found. The dielectric constant, dielectric loss, energy loss functions were also determined.

  5. Spectroscopic ellipsometry of Zn1-xCuxO thin films based on a modified sol-gel dip-coating technique

    NASA Astrophysics Data System (ADS)

    Al-Khanbashi, Hibah A.; Shirbeeny, W.; Al-Ghamdi, A. A.; Bronstein, Lyudmila M.; Mahmoud, Waleed E.

    2014-01-01

    Nanocrystalline Zn1-xCuxO thin films (x = 0, 0.01, 0.02, 0.03, 0.04 and 0.05) were synthesized by sol-gel dip-coating technique on a quartz substrate. These films were annealed at 350 °C for 2 h. The X-ray diffraction showed a hexagonal crystal structure with high intensity peak for the (0 0 2) reflection plane indicating preferential growth along the c-axis of the crystal lattice. The peak position related to the (0 0 2) peak was shifted as a result of the copper ion incorporation, confirming the interstitial substitution of the zinc ions by the copper ions. This interstitial substitution leads to a decrease of an average crystallite size and lattice constants and an increase of the micro-strain up to 2 at.% of the copper amount. The surface morphology was explored by scanning electron microscopy which confirmed the homogenous distribution of nanoparticles in the deposited films along the quartz substrates. The energy dispersion X-ray spectroscopy revealed absence of impurities in the as-deposited films. The high resolution electron microscopy and selected area electron diffraction depicted that the films have polycrystalline nature. The film thickness and optical constants of the Zn1-xCuxO thin films were estimated by fitting the spectroscopic ellipsometric data (ψ and Δ) using three different models. The refractive index was fitted using harmonic oscillator model from which the oscillator and the dispersive energies were found. The dielectric constant, dielectric loss, energy loss functions were also determined.

  6. Magic Angle Spinning NMR Spectroscopy: A Versatile Technique for Structural and Dynamic Analysis of Solid-Phase Systems

    PubMed Central

    Polenova, Tatyana; Gupta, Rupal; Goldbourt, Amir

    2016-01-01

    Magic Angle Spinning (MAS) NMR spectroscopy is a powerful method for analysis of a broad range of systems, including inorganic materials, pharmaceuticals, and biomacromolecules. The recent developments in MAS NMR instrumentation and methodologies opened new vistas to atomic-level characterization of a plethora of chemical environments previously inaccessible to analysis, with unprecedented sensitivity and resolution. PMID:25794311

  7. Spins, stripes, and superconductivity in hole-doped cuprates

    NASA Astrophysics Data System (ADS)

    Tranquada, John M.

    2013-08-01

    One of the major themes in correlated electron physics over the last quarter century has been the problem of high-temperature superconductivity in hole-doped copper-oxide compounds. Fundamental to this problem is the competition between antiferromagnetic spin correlations, a symptom of strong Coulomb interactions, and the kinetic energy of the doped carriers, which favors delocalization. After discussing some of the early challenges in the field, I describe the experimental picture provided by a variety of spectroscopic and transport techniques. Then I turn to the technique of neutron scattering, and discuss how it is used to determine spin correlations, especially in model systems of quantum magnetism. Neutron scattering and complementary techniques have determined the extent to which antiferromagnetic spin correlations survive in the cuprate superconductors. One experimental case involves the ordering of spin and charge stripes. I first consider related measurements on model compounds, such as La2-xSrxNiO4+δ, and then discuss the case of La2-xBaxCuO4. In the latter system, recent transport studies have demonstrated that quasi-two-dimensional superconductivity coexists with the stripe order, but with frustrated phase order between the layers. This has led to new concepts for the coexistence of spin order and superconductivity. While the relevance of stripe correlations to high-temperature superconductivity remains a subject of controversy, there is no question that stripes are an intriguing example of electron matter that results from strong correlations.

  8. Thick-Dielectric Formation and MOSFET Reliability with Spin-Coating Film Transfer and Hot-Pressing Technique for Seamless Integration Technology

    NASA Astrophysics Data System (ADS)

    Sato, Norio; Shimoyama, Nobuhiro; Kamei, Toshikazu; Kudou, Kazuhisa; Yano, Masaki; Ishii, Hiromu; Machida, Katsuyuki

    2004-04-01

    The formation of thick dielectrics by the spin-coating film transfer and hot-pressing (STP) technique is proposed for the fabrication of thick multilevel interconnects. Examination of the characteristics of 20-μm-thick dielectrics on 10-μm-thick line-and-space patterns shows sufficient planarization capability with little dependence on pattern density, which enables the fabrication of a double layer of thick interconnects. To investigate the influence of hot pressing in the STP process on LSIs, the hot-carrier degradation of n-channel metal oxide semiconductor field-effect transistors (MOSFETs) was evaluated. The lifetime of transconductance gm of STP samples was estimated to be over ten years, which is the same as that of samples prepared by the conventional technique of spin-coating. Moreover, the lifetime showed no dependence on pressure, temperature in hot pressing and thickness of dielectrics. These results confirm that the STP technique is applicable to the fabrication of thick interconnects and does not damage the underlying MOSFETs.

  9. Gd doping effect on structural, electrical and magnetic properties of ZnO thin films synthesized by sol-gel spin coating technique

    NASA Astrophysics Data System (ADS)

    Kumar, Sanjeev; Thangavel, Rajalingam

    2017-03-01

    Nanocrystalline Gd-doped ZnO thin films were deposited on sapphire (0001) substrates using sol-gel spin coating technique. The structural and optical properties of deposited thin films were characterized by X-ray diffraction (XRD) and micro Raman spectroscopy. Structural and optical studies show that the doped Gd ions occupy Zn sites retaining the wurtzite symmetry. Photoluminescence (PL) studies reveal the presence of oxygen vacancies in Gd doped ZnO thin films. The resistivity of Gd doped ZnO thin film decreases with increase in Gd doping upto 4%. Gd-doped ZnO films demonstrate weak magnetic ordering at room temperature.

  10. Search for α-decay of high-spin isomers in rare-earth nuclei using a decay-in-flight technique

    SciTech Connect

    Vrba, Joseph A.

    1980-03-01

    An experimental search has been conducted for α-decay in the lifetime range of from 1 to 100 nsec in a variety of rare earth nuclei produced in reactions of 125 to 146 MeV /sup 16/O ions on targets of /sup 139/La, /sup 141/Pr, and /sup 142/Nd. The products of these reactions include systems in which high spin (I > 10 h-bar) isomeric states have been observed with lifetimes in the range studied. Certain of these isomers may be very high spin statistical yrast traps which have been predicted to occur at spins of from 30 to 50 h-bar in the rare earths. For such spins and lifetimes, calculations suggest that α-decay could be a major mode of de-excitation. The technique employed for these experimental investigations made use of a specially designed trajectory detector to observe α-decay directly from the reaction products which recoiled from a thin target. Analytical procedures developed for reduction of the decay-in-flight data are discussed which yielded information about the particle types detected, the energies of these particles, the trajectories followed, and the positions of parent nuclei at the time the detected particles were emitted. Kinematic and solid angle corrections are considered which permitted correction for Doppler broadening effects and allowed estimates to be made with regard to the lifetime and production cross section of the parent state. The experimental method and the associated analytical procedures were verified by study of α-decay following the reaction /sup 208/Pb(/sup 16/O,p6n)/sup 217/Ac. No system studied in the search for yrast trap α-decay showed activity significantly above background in the 6 to 16 MeV energy range.

  11. An in-line micro-pyrolysis system to remove contaminating organic species for precise and accurate water isotope analysis by spectroscopic techniques

    NASA Astrophysics Data System (ADS)

    Panetta, R. J.; Hsiao, G.

    2011-12-01

    Trace levels of organic contaminants such as short alcohols and terpenoids have been shown to cause spectral interference in water isotope analysis by spectroscopic techniques. The result is degraded precision and accuracy in both δD and δ18O for samples such as beverages, plant extracts or slightly contaminated waters. An initial approach offered by manufacturers is post-processing software that analyzes spectral features to identify and flag contaminated samples. However, it is impossible for this software to accurately reconstruct the water isotope signature, thus it is primarily a metric for data quality. Here, we describe a novel in-line pyrolysis system (Micro-Pyrolysis Technology, MPT) placed just prior to the inlet of a cavity ring-down spectroscopy (CRDS) analyzer that effectively removes interfering organic molecules without altering the isotope values of the water. Following injection of the water sample, N2 carrier gas passes the sample through a micro-pyrolysis tube heated with multiple high temperature elements in an oxygen-free environment. The temperature is maintained above the thermal decomposition threshold of most organic compounds (≤ 900 oC), but well below that of water (~2000 oC). The main products of the pyrolysis reaction are non-interfering species such as elemental carbon and H2 gas. To test the efficacy and applicability of the system, waters of known isotopic composition were spiked with varying amounts of common interfering alcohols (methanol, ethanol, propanol, hexanol, trans-2-hexenol, cis-3-hexanol up to 5 % v/v) and common soluble plant terpenoids (carveol, linalool, geraniol, prenol). Spiked samples with no treatment to remove the organics show strong interfering absorption peaks that adversely affect the δD and δ18O values. However, with the MPT in place, all interfering absorption peaks are removed and the water absorption spectrum is fully restored. As a consequence, the δD and δ18O values also return to their original

  12. Spin foams without spins

    NASA Astrophysics Data System (ADS)

    Hnybida, Jeff

    2016-10-01

    We formulate the spin foam representation of discrete SU(2) gauge theory as a product of vertex amplitudes each of which is the spin network generating function of the boundary graph dual to the vertex. In doing so the sums over spins have been carried out. The boundary data of each n-valent node is explicitly reduced with respect to the local gauge invariance and has a manifest geometrical interpretation as a framed polyhedron of fixed total area. Ultimately, sums over spins are traded for contour integrals over simple poles and recoupling theory is avoided using generating functions.

  13. Spectroscopic detection

    DOEpatents

    Woskov, Paul P.; Hadidi, Kamal

    2003-01-01

    In embodiments, spectroscopic monitor monitors modulated light signals to detect low levels of contaminants and other compounds in the presence of background interference. The monitor uses a spectrometer that includes a transmissive modulator capable of causing different frequency ranges to move onto and off of the detector. The different ranges can include those with the desired signal and those selected to subtract background contributions from those with the desired signal. Embodiments of the system are particularly useful for monitoring metal concentrations in combustion effluent.

  14. Spin Interactions and Spin Dynamics in Electronic Nanostructures

    DTIC Science & Technology

    2007-11-02

    of technological importance, and the spectroscopic study of the spin transport properties of nanoscale systems, the demonstration of terahertz spin...dynamics at near- terahertz frequencies in magnetically doped quantum wells,” R. C. Myers. K. C. Ku, X. Li, N. Samarth, and D. D. Awschalom, Phys. Rev. B 72...dynamics at near- terahertz frequencies in magnetically doped quantum wells,” R. C. Myers. K. C. Ku, X. Li, N. Samarth, and D. D. Awschalom, Phys. Rev

  15. Kinetic effects on double hysteresis in spin crossover molecular magnets analyzed with first order reversal curve diagram technique

    SciTech Connect

    Stan, Raluca-Maria; Gaina, Roxana; Enachescu, Cristian E-mail: radu.tanasa@uaic.ro; Stancu, Alexandru; Tanasa, Radu E-mail: radu.tanasa@uaic.ro; Bronisz, Robert

    2015-05-07

    In this paper, we analyze two types of hysteresis in spin crossover molecular magnets compounds in the framework of the First Order Reversal Curve (FORC) method. The switching between the two stable states in these compounds is accompanied by hysteresis phenomena if the intermolecular interactions are higher than a threshold. We have measured the static thermal hysteresis (TH) and the kinetic light induced thermal hysteresis (LITH) major loops and FORCs for the polycrystalline Fe(II) spin crossover compound [Fe{sub 1−x}Zn{sub x}(bbtr){sub 3}](ClO{sub 4}){sub 2} (bbtr = 1,4-di(1,2,3-triazol-1-yl)butane), either in a pure state (x = 0) or doped with Zn ions (x = 0.33) considering different sweeping rates. Here, we use this method not only to infer the domains distribution but also to disentangle between kinetic and static components of the LITH and to estimate the changes in the intermolecular interactions introduced by dopants. We also determined the qualitative relationship between FORC distributions measured for TH and LITH.

  16. 3D Fast Spin Echo With Out-of-Slab Cancellation: A Technique for High-Resolution Structural Imaging of Trabecular Bone at 7 Tesla

    PubMed Central

    Magland, Jeremy F.; Rajapakse, Chamith S.; Wright, Alexander C.; Acciavatti, Raymond; Wehrli, Felix W.

    2016-01-01

    Spin-echo-based pulse sequences are desirable for the application of high-resolution imaging of trabecular bone but tend to involve high-power deposition. Increased availability of ultrahigh field scanners has opened new possibilities for imaging with increased signal-to-noise ratio (SNR) efficiency, but many pulse sequences that are standard at 1.5 and 3 T exceed specific absorption rate limits at 7 T. A modified, reduced specific absorption rate, three-dimensional, fast spin-echo pulse sequence optimized specifically for in vivo trabecular bone imaging at 7 T is introduced. The sequence involves a slab-selective excitation pulse, low-power nonselective refocusing pulses, and phase cycling to cancel undesired out-of-slab signal. In vivo images of the distal tibia were acquired using the technique at 1.5, 3, and 7 T field strengths, and SNR was found to increase at least linearly using receive coils of identical geometry. Signal dependence on the choice of refocusing flip angles in the echo train was analyzed experimentally and theoretically by combining the signal from hundreds of coherence pathways, and it is shown that a significant specific absorption rate reduction can be achieved with negligible SNR loss. PMID:20187181

  17. Preparation, ferromagnetic and photocatalytic performance of NiO and hollow Co{sub 3}O{sub 4} fibers through centrifugal-spinning technique

    SciTech Connect

    Feng, Cong; Lin, Xuejun; Wang, Xinqiang Liu, Hongjing; Liu, Benxue; Zhu, Luyi; Zhang, Guanghui; Xu, Dong

    2016-02-15

    Highlights: • NiO and hollow Co{sub 3}O{sub 4} fibers with the diameter of about 10 μm were prepared through centrifugal-spinning technique. • The evolution mechanism from precursor to crystalline fibers was explored. • Both NiO and hollow Co{sub 3}O{sub 4} fibers show ferromagnetism. • The NiO fibers exhibit good photocatalytic performance. - Abstract: Both NiO and hollow Co{sub 3}O{sub 4} fibers with the diameter of about 10 μm have been successfully prepared through spinning high viscous sols into precursor fibers and followed calcination process. The evolution process from precursor to crystalline fibers and the microstructures of the obtained fibers were characterized by TG-DSC, FT-IR, XRD, HRTEM, SEM and the like. The method is facile and cost-effective for mass production of fibers and the obtained fibers are pure phase with high crystallinity. Their magnetic properties were investigated, showing that both the fibers are ferromagnetic. Meanwhile, the NiO fibers exhibit good photocatalytic performance for the removal of Congo red from water under UV light irradiation.

  18. Spectroscopic properties of Eu3+, Dy3+ and Tb3+ ions in lead silicate glasses obtained by the conventional high-temperature melt-quenching technique

    NASA Astrophysics Data System (ADS)

    Żur, L.; Janek, J.; Sołtys, M.; Pisarska, J.; Pisarski, W. A.

    2013-11-01

    The luminescence properties of selected rare-earth ions in lead silicate glasses have been studied. Europium, dysprosium and terbium ions were chosen as active dopants. Based on excitation and emission measurements as well as luminescence decay analysis, some spectroscopic parameters for these lanthanide ions were determined. In particular, the intensity ratios R/O (Eu3+), Y/B (Dy3+) and G/B (Tb3+) were calculated. Luminescence lifetimes for the 5D0 state of Eu3+ ions, the 4F9/2 state of Dy3+ ions and the 5D4 state of Tb3+ ions were also determined.

  19. Effect of Fe incorporation on the optical behavior of ZnO thin films prepared by sol-gel derived spin coating techniques

    NASA Astrophysics Data System (ADS)

    Rakkesh, R. Ajay; Malathi, R.; Balakumar, S.

    2013-02-01

    In this work, Fe doped Zinc Oxide (ZnO) thin films were fabricated on the glass substrate by sol-gel derived spin coating technique. X-ray Diffraction studies revealed that the obtained pure and Fe doped ZnO thin films were in the wurtzite and spinel phase respectively. The three well defined Raman lines at 432, 543 and 1091 cm-1 also confirmed the lattice structure of the ZnO thin film has wurtzite symmetry. While doping Fe atoms in the ZnO, there was a significant change in the phase from wurtzite to spinel structure; owing to Fe (III) ions being incorporated into the lattice through substitution of Zn (II) ions. Room temperature PL spectra showed that the role of defect mediated red emissions at 612 nm was due to radial recombination of a photogenerated hole with an electron that belongs to the Fe atoms, which were discussed in detail.

  20. Technique paper for wet-spinning poly(L-lactic acid) and poly(DL-lactide-co-glycolide) monofilament fibers.

    PubMed

    Nelson, Kevin D; Romero, Andres; Waggoner, Paula; Crow, Brent; Borneman, Angela; Smith, George M

    2003-12-01

    A simple and repeatable method is described for wet-spinning poly(L-lactic acid) (PLLA) and poly(DL-lactic-co-glycolic acid) (PLGA) monofilament fibers. These fibers are strong, elastic, and suitable for many applications, including use as tissue-engineering scaffolds. The PLLA wet-extruded fibers do not show additional strain-induced crystallization as a result of drawing the fibers during fabrication; however, there is an apparent increase in crystallinity late in the degradation process in saline at 37 degrees C. We have measured the molecular weight degradation in saline at 37 degrees C for fibers of both PLLA and PLGA. Changing solvent systems, polymer blends, and winding rates alters mechanical and morphological properties of these fibers for specific applications. The authors discuss a possible theoretical explanation for these observed changes due to changes in polymer concentration, solvent system, and coagulation bath properties. This wet-extrusion process is simple and inexpensive enough to be carried out in almost any laboratory interested in tissue engineering.

  1. Microscopic studies of nonlocal spin dynamics and spin transport (invited)

    SciTech Connect

    Adur, Rohan; Du, Chunhui; Cardellino, Jeremy; Scozzaro, Nicolas; Wolfe, Christopher S.; Wang, Hailong; Herman, Michael; Bhallamudi, Vidya P.; Pelekhov, Denis V.; Yang, Fengyuan; Hammel, P. Chris

    2015-05-07

    Understanding the behavior of spins coupling across interfaces in the study of spin current generation and transport is a fundamental challenge that is important for spintronics applications. The transfer of spin angular momentum from a ferromagnet into an adjacent normal material as a consequence of the precession of the magnetization of the ferromagnet is a process known as spin pumping. We find that, in certain circumstances, the insertion of an intervening normal metal can enhance spin pumping between an excited ferromagnetic magnetization and a normal metal layer as a consequence of improved spin conductance matching. We have studied this using inverse spin Hall effect and enhanced damping measurements. Scanned probe magnetic resonance techniques are a complementary tool in this context offering high resolution magnetic resonance imaging, localized spin excitation, and direct measurement of spin lifetimes or damping. Localized magnetic resonance studies of size-dependent spin dynamics in the absence of lithographic confinement in both ferromagnets and paramagnets reveal the close relationship between spin transport and spin lifetime at microscopic length scales. Finally, detection of ferromagnetic resonance of a ferromagnetic film using the photoluminescence of nitrogen vacancy spins in neighboring nanodiamonds demonstrates long-range spin transport between insulating materials, indicating the complexity and generality of spin transport in diverse, spatially separated, material systems.

  2. Spin Hall effect and spin swapping in diffusive superconductors

    NASA Astrophysics Data System (ADS)

    Espedal, Camilla; Lange, Peter; Sadjina, Severin; Mal'shukov, A. G.; Brataas, Arne

    2017-02-01

    We consider the spin-orbit-induced spin Hall effect and spin swapping in diffusive superconductors. By employing the nonequilibrium Keldysh Green's function technique in the quasiclassical approximation, we derive coupled transport equations for the spectral spin and particle distributions and for the energy density in the elastic scattering regime. We compute four contributions to the spin Hall conductivity, namely, skew scattering, side jump, anomalous velocity, and the Yafet contribution. The reduced density of states in the superconductor causes a renormalization of the spin Hall angle. We demonstrate that all four of these contributions to the spin Hall conductivity are renormalized in the same way in the superconducting state. In its simplest manifestation, spin swapping transforms a primary spin current into a secondary spin current with swapped current and polarization directions. We find that the spin-swapping coefficient is not explicitly but only implicitly affected by the superconducting gap through the renormalized diffusion coefficients. We discuss experimental consequences for measurements of the (inverse) spin Hall effect and spin swapping in four-terminal geometries. In our geometry, below the superconducting transition temperature, the spin-swapping signal is increased an order of magnitude while changes in the (inverse) spin Hall signal are moderate.

  3. Microscopic studies of nonlocal spin dynamics and spin transport (invited)

    NASA Astrophysics Data System (ADS)

    Adur, Rohan; Du, Chunhui; Cardellino, Jeremy; Scozzaro, Nicolas; Wolfe, Christopher S.; Wang, Hailong; Herman, Michael; Bhallamudi, Vidya P.; Pelekhov, Denis V.; Yang, Fengyuan; Hammel, P. Chris

    2015-05-01

    Understanding the behavior of spins coupling across interfaces in the study of spin current generation and transport is a fundamental challenge that is important for spintronics applications. The transfer of spin angular momentum from a ferromagnet into an adjacent normal material as a consequence of the precession of the magnetization of the ferromagnet is a process known as spin pumping. We find that, in certain circumstances, the insertion of an intervening normal metal can enhance spin pumping between an excited ferromagnetic magnetization and a normal metal layer as a consequence of improved spin conductance matching. We have studied this using inverse spin Hall effect and enhanced damping measurements. Scanned probe magnetic resonance techniques are a complementary tool in this context offering high resolution magnetic resonance imaging, localized spin excitation, and direct measurement of spin lifetimes or damping. Localized magnetic resonance studies of size-dependent spin dynamics in the absence of lithographic confinement in both ferromagnets and paramagnets reveal the close relationship between spin transport and spin lifetime at microscopic length scales. Finally, detection of ferromagnetic resonance of a ferromagnetic film using the photoluminescence of nitrogen vacancy spins in neighboring nanodiamonds demonstrates long-range spin transport between insulating materials, indicating the complexity and generality of spin transport in diverse, spatially separated, material systems.

  4. MR chemical exchange imaging with spin-lock technique (CESL): a theoretical analysis of the Z-spectrum using a two-pool R1ρ relaxation model beyond the fast-exchange limit

    NASA Astrophysics Data System (ADS)

    Yuan, Jing; Zhou, Jinyuan; Ahuja, Anil T.; Wang, Yi-Xiang J.

    2012-12-01

    The chemical exchange (CE) process has been exploited as a novel and powerful contrast mechanism for MRI, which is primarily performed in the form of chemical exchange saturation transfer (CEST) imaging. A spin-lock (SL) technique can also be used for CE studies, although traditionally performed and interpreted quite differently from CEST. Chemical exchange imaging with spin-lock technique (CESL), theoretically based on the Bloch-McConnell equations common to CEST, has the potential to be used as an alternative to CEST and to better characterize CE processes from slow and intermediate to fast proton exchange rates through the tuning of spin-lock pulse parameters. In this study, the Z-spectrum and asymmetric magnetization transfer ratio (MTRasym) obtained by CESL are theoretically analyzed and numerically simulated using a general two-pool R1ρ relaxation model beyond the fast-exchange limit. The influences of spin-lock parameters, static magnetic field strength B0 and physiological properties on the Z-spectrum and MTRasym are quantitatively revealed. Optimization of spin-lock frequency and spin-lock duration for the maximum CESL contrast enhancement is also investigated. Numerical simulation results in this study are compatible with the findings in the existing literature on CE imaging studies.

  5. Observing Black Hole Spin

    NASA Astrophysics Data System (ADS)

    Reynolds, Christopher S.

    2015-08-01

    Black hole spin is important in both the fundamental physics and astrophysics realms. In fundamental terms, many extensions and alternatives to General Relativity (GR) reveal themselves through effects related to (or at least of the same order as) spin. Astrophysically, spin is a fossil record of how black holes have grown and may, in addition, be an important source of energy (e.g., powering relativistic jets from black hole systems). I shall review recent progress on observational studies of black hole spin, especially those made in the X-ray waveband. We now have multiple techniques that can be applied in our search for black hole spin; I shall discuss the concordance (or, sometimes, lack thereof) between these techniques. Finally, I shall discuss what we can expect in the next few years with the launch of new X-ray instrumentation as well as the deployment of the Event Horizon Telescope.

  6. Quantitative analysis of the breath-holding half-Fourier acquisition single-shot turbo spin-echo technique in abdominal MRI

    NASA Astrophysics Data System (ADS)

    Dong, Kyung-Rae; Goo, Eun-Hoe; Lee, Jae-Seung; Chung, Woon-Kwan

    2013-01-01

    A consecutive series of 50 patients (28 males and 22 females) who underwent hepatic magnetic resonance imaging (MRI) from August to December 2011 were enrolled in this study. The appropriate parameters for abdominal MRI scans were determined by comparing the images (TE = 90 and 128 msec) produced using the half-Fourier acquisition single-shot turbo spin-echo (HASTE) technique at different signal acquisition times. The patients consisted of 15 normal patients, 25 patients with a hepatoma and 10 patients with a hemangioma. The TE in a single patient was set to either 90 msec or 128 msec. This was followed by measurements using the four normal rendering methods of the biliary tract system and the background signal intensity using the maximal signal intensity techniques in the liver, spleen, pancreas, gallbladder, fat, muscles and hemangioma. The signal-to-noise and the contrast-to-noise ratios were obtained. The image quality was assessed subjectively, and the results were compared. The signal-to-noise and the contrast-to-noise ratios were significantly higher at TE = 128 msec than at TE = 90 when diseases of the liver, spleen, pancreas, gallbladder, and fat and muscles, hepatocellular carcinomas and hemangiomas, and rendering the hepatobiliary tract system based on the maximum signal intensity technique were involved (p < 0.05). In addition, the presence of artifacts, the image clarity and the overall image quality were excellent at TE = 128 msec (p < 0.05). In abdominal MRI, the breath-hold half-Fourier acquisition single-shot turbo spin-echo (HASTE) was found to be effective in illustrating the abdominal organs for TE = 128 msec. Overall, the image quality at TE = 128 msec was better than that at TE = 90 msec due to the improved signal-to-noise (SNR) and contrast-to-noise (CNR) ratios. Overall, the HASTE technique for abdominal MRI based on a high-magnetic field (3.0 T) at a TE of 128 msec can provide useful data.

  7. Spectroscopic characterization of polymers: report

    SciTech Connect

    Koenig, J.L.

    1987-10-01

    Polymer characterization has presented major difficulties to the analytical chemist, who has had to develop techniques to cope with the challenge. Even the elementary problem of measuring molecular weight is not easy. Yet such measurements are essential, because the physical, mechanical, and flow properties depend on the length of the polymer chain. Because of the limited solubility and high viscosity of polymers, many classical techniques have been of little use or have had to be extensively modified to measure the molecular weight of polymers. Size-exclusion chromatographic techniques such as gel permeation have been developed to measure these molecular weight distributions. Special chromatographic instruments with a range of spectroscopic detectors (including infrared and laser-light scattering) have emerged commercially to aid the analytical chemist in the fundamental endeavor to measure the length of the polymer chain and its distribution. The author describes the advantages and disadvantages and disadvantages of various spectroscopic techniques.

  8. The application of thermodynamic and spectroscopic techniques to adhesion in the polyimide/Ti 6-4 and polyphenylquinoxaline/Ti 6-4 systems

    NASA Technical Reports Server (NTRS)

    Dias, S.; Wightman, J. P.

    1984-01-01

    The results of calorimetric measurements of Ti adherend surfaces are presented. The measurements were carried out after several chemical pretreatments and after fracture of several lap shear samples aged at high temperature. The exact composition of the Ti samples was Ti(6 percent Al-4 percent V). The adhesives used were polyimides and polyphenylquinoxalines (PPQ). Each chemical pretreatment was accompanied by a unique spectroscopic feature which was characterized by XPS, SEM, and specular reflectance infrared spectroscopy. The energetics of the interaction between primer solutions and the Ti adherend were evaluated by microcalorimetry. Changes in the structure of the surface oxide layer upon heating of the adherend were deduced from immersion temperatures of the PI and PPQ solutions. The XPS and SEM data are given is a table.

  9. Optical Pumping of Rubidium Spin in a Solid Argon Matrix

    NASA Astrophysics Data System (ADS)

    Regmi, Sameer K.

    Using the matrix isolation technique we have trapped rubidium atoms inside a cryogenic solid argon crystal of thickness 200 mum. This weakly-interacting solid offers the experimental simplicity and high densities of solid-state systems, while allowing the implanted atoms to retain many of the properties of their gas-phase counterparts. As such, they are a promising environment for quantum information experiments, as well as sensors such as magnetometers. We spectroscopically observed narrow lines at 799 nm, 785 nm, and 747 nm, and investigated optical pumping of the implanted rubidium atoms. We observed that the absorption spectrum of the rubidium could be modified by incident laser light. This modification could be reversed by applying an additional light source. In addition, we were able to create spin polarization and measure a longitudinal spin relaxation time T1 of about 0.1 s.

  10. Influence of Ga doping ratio on the saturable absorption mechanism in Ga doped ZnO thin solid films processed by sol–gel spin coating technique

    NASA Astrophysics Data System (ADS)

    Sandeep, K. M.; Bhat, Shreesha; Dharmaprakash, S. M.; Byrappa, K.

    2017-03-01

    In the present study, the nonlinear optical properties of sol–gel spin coated gallium doped zinc oxide (GZO) thin solid films are explored with nanosecond laser pulses using the z-scan technique. The higher doping ratios of Ga result in a large redshift of the energy gap (0.38 eV) due to the existence of enhanced grain boundary defects in GZO films. A positive nonlinear absorption coefficient is observed in undoped 1 at.wt.% GZO and 2 at.wt.% GZO films, and a negative nonlinear absorption coefficient in 3 at.wt.% GZO film. Fewer defects in undoped 1% GZO and 2% GZO films resulted in reverse saturable absorption (RSA), whereas a saturable absorption (SA) mechanism is observed in 3% GZO films and is attributed to the enhanced defect concentration in the band structure of GZO. However, all the films showed a self-defocusing mechanism, derived by a closed aperture z-scan technique. The present work sheds light on the defect mechanism involved in the observed nonlinear properties of GZO films.

  11. Computer-aided classification of patients with dementia of Alzheimer's type based on cerebral blood flow determined with arterial spin labeling technique

    NASA Astrophysics Data System (ADS)

    Yamashita, Yasuo; Arimura, Hidetaka; Yoshiura, Takashi; Tokunaga, Chiaki; Magome, Taiki; Monji, Akira; Noguchi, Tomoyuki; Toyofuku, Fukai; Oki, Masafumi; Nakamura, Yasuhiko; Honda, Hiroshi

    2010-03-01

    Arterial spin labeling (ASL) is one of promising non-invasive magnetic resonance (MR) imaging techniques for diagnosis of Alzheimer's disease (AD) by measuring cerebral blood flow (CBF). The aim of this study was to develop a computer-aided classification system for AD patients based on CBFs measured by the ASL technique. The average CBFs in cortical regions were determined as functional image features based on the CBF map image, which was non-linearly transformed to a Talairach brain atlas by using a free-form deformation. An artificial neural network (ANN) was trained with the CBF functional features in 10 cortical regions, and was employed for distinguishing patients with AD from control subjects. For evaluation of the method, we applied the proposed method to 20 cases including ten AD patients and ten control subjects, who were scanned a 3.0-Tesla MR unit. As a result, the area under the receiver operating characteristic curve obtained by the proposed method was 0.893 based on a leave-one-out-by-case test in identification of AD cases among 20 cases. The proposed method would be feasible for classification of patients with AD.

  12. High-spin states in 208Rn

    NASA Astrophysics Data System (ADS)

    Triggs, W. J.; Poletti, A. R.; Dracoulis, G. D.; Fahlander, C.; Byrne, A. P.

    1983-03-01

    The yrast decay scheme of 208Rn has been investigated up to spin ≈ 20 h̵ and an excitation energy of ≈ 6 MeV. Several different γ-ray spectroscopic techniques were used to determine the properties of excited states and transitions in the nucleus. Significant changes to the previously established level scheme are proposed, based on the existence of an unobserved 3.1 keV transition. Simple empirical shell-model calculations of level energies aided in the assignment of shell-model configurations to excited states and the decay scheme is discussed in terms of these configurations. The energy level systematics for the even radon isotopes, from A = 206 to 212 are discussed, as are core polarization effects in the even radon isotopes ( A = 204 to 210) and polonium isotopes ( A = 202-208).

  13. Thermal- and light-induced spin crossover in novel 2D Fe(II) metalorganic frameworks {Fe(4-PhPy)(2)[M(II)(CN)(x)](y)}.sH(2)O: spectroscopic, structural, and magnetic studies.

    PubMed

    Seredyuk, M; Gaspar, A B; Ksenofontov, V; Verdaguer, M; Villain, F; Gütlich, P

    2009-07-06

    Five novel two-dimensional coordination polymers {Fe(4PhPy)(2)[M(II)(CN)(4)]}.sH(2)O (4PhyPy = 4-phenylpyridine; 1: M(II) = Pd, s = 0; 2: M(II) = Ni, s = 0; 3: M(II) = Pt, s = 1) and {Fe(4PhPy)(2)[M(I)(CN)(2)](2)}.sH(2)O (4: M(I) = Ag, s = 1; 5: M(I) = Au, s = 0.5) exhibiting spin-crossover properties have been synthesized. They were characterized at various temperatures using X-ray absorption spectroscopy (XAS), powder X-ray diffraction (PXRD), differential scanning calorimetry (DSC), and magnetic susceptibility measurements. The occurrence of a cooperative thermal spin transition detected by the magnetic method is located at critical temperatures T(c)( downward arrow)/T(c)( upward arrow) = 163 K/203 K (1), 135 K/158 K (2), and 172 K/221 K (3), and a less cooperative one is located at T(c) = 188 K (4) and 225 K (5). Compounds 1-5 show an abrupt color change from yellow (high-spin (HS) state) to red (low-spin (LS) state) upon spin-state conversion. The dehydration of the compounds changes the type of the spin transition, making it more abrupt and shifting the critical temperature to higher temperatures. For 1 and 2, XAS provides local structural information on the contraction of the FeN(6) coordination sphere upon the HS-to-LS transition, in line with the magnetic results. Variable-temperature characterization of 1 by X-ray diffraction evidences the very abrupt phase transition with a large hysteresis. A light-induced spin conversion (LIESST effect) is detected by magnetic measurements in 1-5 below 70 K.

  14. Positron surface state as a spectroscopic probe for characterizing surfaces of topological insulator materials

    NASA Astrophysics Data System (ADS)

    Callewaert, Vincent; Shastry, K.; Saniz, Rolando; Makkonen, Ilja; Barbiellini, Bernardo; Assaf, Badih A.; Heiman, Donald; Moodera, Jagadeesh S.; Partoens, Bart; Bansil, Arun; Weiss, A. H.

    2016-09-01

    Topological insulators are attracting considerable interest due to their potential for technological applications and as platforms for exploring wide-ranging fundamental science questions. In order to exploit, fine-tune, control, and manipulate the topological surface states, spectroscopic tools which can effectively probe their properties are of key importance. Here, we demonstrate that positrons provide a sensitive probe for topological states and that the associated annihilation spectrum provides a technique for characterizing these states. Firm experimental evidence for the existence of a positron surface state near Bi2Te2Se with a binding energy of Eb=2.7 ±0.2 eV is presented and is confirmed by first-principles calculations. Additionally, the simulations predict a significant signal originating from annihilation with the topological surface states and show the feasibility to detect their spin texture through the use of spin-polarized positron beams.

  15. Detection of β-amyloid peptide (1-16) and amyloid precursor protein (APP770) using spectroscopic ellipsometry and QCM techniques: a step forward towards Alzheimers disease diagnostics.

    PubMed

    Mustafa, M K; Nabok, A; Parkinson, D; Tothill, I E; Salam, F; Tsargorodskaya, A

    2010-12-15

    A highly sensitive method of spectroscopic ellipsometry in total internal reflection mode (TIRE) was exploited for detecting β-amyloid peptide (Aβ(1-16)) in the direct immune reaction with monoclonal DE2 antibodies (raised against Aβ(1-16)) electrostatically immobilised on the surface of gold. A rapid detection of Aβ(1-16) in a wide range of concentrations from 5 μg/ml down to 0.05 ng/ml was achieved using a cost-effective and label-free direct immunoassay format. TIRE dynamic spectral measurements proved that the immune reaction between DE2 monoclonal antibodies and Aβ(1-16) is highly specific with the affinity constant K(D)=1.46×10(-8) mol/l. The same DE2 antibodies were utilised for detection of amyloid precursor protein APP(770), a larger protein containing Aβ(1-16) domain, using the quartz crystal microbalance (QCM) measurements in liquid. A combination of QCM and TIRE kinetics results allowed the evaluation of the originally unknown concentration of APP(770) in complete medium solution containing other proteins, salts, and amino acids.

  16. Study on the interaction between pelargonidin-3-O-glucoside and bovine serum albumin using spectroscopic, transmission electron microscopy and molecular modeling techniques.

    PubMed

    Li, Shu; Tang, Lin; Bi, Hongna

    2016-03-01

    The aim of this study is to evaluate the binding behavior between pelargonidin-3-O-glucoside (P3G) and bovine serum albumin (BSA) using multi-spectroscopic, transmission electron microscopy (TEM) and molecular docking methods under physiological conditions. Fluorescence spectroscopy and time-resolved fluorescence showed that the fluorescence of BSA could be quenched remarkably by P3G via a static quenching mechanism, and there is a single class of binding site on BSA. In addition, the thermodynamic functions ΔH and ΔS were -21.69 kJ/mol and 24.46 J/mol/K, indicating that an electrostatic interaction was a main acting force. The distance between BSA and P3G was 2.74 nm according to Förster's theory, illustrating that energy transfer occurred. In addition, the secondary structure of BSA changed with a decrease in the α-helix content from 66.2% to 64.0% as seen using synchronous fluorescence, UV/vis, circular dichroism and Fourier transform infrared spectroscopies, whereas TEM images showed that P3G led to BSA aggregation and fibrillation. Furthermore, site marker competitive experiments and molecular docking indicated that P3G could bind with subdomain IIA of BSA. The calculated results of the equilibrium fraction showed that the concentration of free P3G in plasma was high enough to be stored and transported from the circulatory system to its target sites to provide therapeutic effects.

  17. Structure analysis and spectroscopic characterization of 2-Fluoro-3-Methylpyridine-5-Boronic Acid with experimental (FT-IR, Raman, NMR and XRD) techniques and quantum chemical calculations

    NASA Astrophysics Data System (ADS)

    Alver, Özgür; Dikmen, Gökhan

    2016-03-01

    Possible stable conformers, geometrical molecular structures, vibrational properties as well as band assignments, nuclear magnetic shielding tensors of 2-Fluoro-3-Methylpyridine-5-Boronic Acid (2F3MP5BA) were studied experimentally and theoretically using FT-IR, Raman, (CP/MAS) NMR and XRD spectroscopic methods. FT-IR and Raman spectra were evaluated in the region of 3500-400 cm-1, and 3200-400 cm-1, respectively. The optimized geometric structures, vibrational wavenumbers and nuclear magnetic shielding tensors were examined using Becke-3-Lee-Yang-Parr (B3LYP) hybrid density functional theory method with 6-311++G(d, p) basis set. 1H, 13C NMR chemical shifts were calculated using the gauge invariant atomic orbital (GIAO) method. 1H, 13C, APT and HETCOR NMR experiments of title molecule were carried out in DMSO solution. 13C CP/MAS NMR measurement was done with 4 mm zirconium rotor and glycine was used as an external standard. Single crystal of 2F3MP5BA was also prepared for XRD measurements. Assignments of vibrational wavenumbers were also strengthened by calculating the total energy distribution (TED) values using scaled quantum mechanical (SQM) method.

  18. Mitigating the hydraulic compression of nanofiltration hollow fiber membranes through a single-step direct spinning technique.

    PubMed

    Ong, Yee Kang; Chung, Tai-Shung

    2014-12-02

    Most nanofiltration (NF) membranes have been made through complicated multistep or thin-film composite processes. They also suffer the compaction issue that reduces permeate flux in pressure-driven filtration processes. A single-step coextrusion hollow fiber fabrication technique via immiscibility induced phase separation (I(2)PS) process is presented in this study to fabricate NF hollow fiber membranes. A protective layer is concurrently formed on top of the selective layer during the phase inversion process. The fabricated hollow fiber membrane has a narrow pore size distribution with a molecular weight cutoff (MWCO) of 470 Da. The outer layer of the I(2)PS hollow fiber is found to serve as a buffering layer that mitigates hydraulic compression on the compaction of dense-selective layer and sublayer and helps to retain membrane performance during nanofiltration operations. The newly fabricated NF hollow fiber membrane exhibits an average pure water permeability of 3.2 L m(-2) h(-1) bar(-1) and shows good rejections toward the testing dyes. This study may offer a simple, direct, and cost-effective approach to fabricate NF hollow fiber membranes.

  19. Synthesis, structural, and spectroscopic (FT-IR, NMR, and UV) Characterization of 1-(Cyclohexylmethyl)-2-(pyridin-2-yl)-1 H-benzo[ d]imidazole by experimental techniques and quantum chemical calculations

    NASA Astrophysics Data System (ADS)

    Özdemir, Namık; Dayan, Osman; Demirmen, Selin

    2016-05-01

    The title compound ( II), 1-(cyclohexylmethyl)-2-(pyridin-2-yl)-1 H-benzo[ d]imidazole (C19H21N3), was synthesized via N-alkylation of 2-(pyridin-2-yl)-1 H-benzo[ d]imidazole ( I). Both compounds I and II were characterized by IR, NMR and UV-vis spectroscopy. Solid-state structure of compound II was determined by single-crystal X-ray diffraction technique. Furthermore, quantum chemical calculations employing density functional theory (DFT/B3LYP) method with the 6-311++ G( d, p) basis set were performed for the theoretical characterization of the molecular and spectroscopic features of the compounds. Using the TD-DFT method, electronic absorption spectra of the compounds have been predicted at same level. When the obtained results were compared with the experimental findings, it is seen that theoretical results support the experimental data and a good agreement exists between them.

  20. Single spin magnetic resonance.

    PubMed

    Wrachtrup, Jörg; Finkler, Amit

    2016-08-01

    Different approaches have improved the sensitivity of either electron or nuclear magnetic resonance to the single spin level. For optical detection it has essentially become routine to observe a single electron spin or nuclear spin. Typically, the systems in use are carefully designed to allow for single spin detection and manipulation, and of those systems, diamond spin defects rank very high, being so robust that they can be addressed, read out and coherently controlled even under ambient conditions and in a versatile set of nanostructures. This renders them as a new type of sensor, which has been shown to detect single electron and nuclear spins among other quantities like force, pressure and temperature. Adapting pulse sequences from classic NMR and EPR, and combined with high resolution optical microscopy, proximity to the target sample and nanoscale size, the diamond sensors have the potential to constitute a new class of magnetic resonance detectors with single spin sensitivity. As diamond sensors can be operated under ambient conditions, they offer potential application across a multitude of disciplines. Here we review the different existing techniques for magnetic resonance, with a focus on diamond defect spin sensors, showing their potential as versatile sensors for ultra-sensitive magnetic resonance with nanoscale spatial resolution.

  1. Single spin magnetic resonance

    NASA Astrophysics Data System (ADS)

    Wrachtrup, Jörg; Finkler, Amit

    2016-08-01

    Different approaches have improved the sensitivity of either electron or nuclear magnetic resonance to the single spin level. For optical detection it has essentially become routine to observe a single electron spin or nuclear spin. Typically, the systems in use are carefully designed to allow for single spin detection and manipulation, and of those systems, diamond spin defects rank very high, being so robust that they can be addressed, read out and coherently controlled even under ambient conditions and in a versatile set of nanostructures. This renders them as a new type of sensor, which has been shown to detect single electron and nuclear spins among other quantities like force, pressure and temperature. Adapting pulse sequences from classic NMR and EPR, and combined with high resolution optical microscopy, proximity to the target sample and nanoscale size, the diamond sensors have the potential to constitute a new class of magnetic resonance detectors with single spin sensitivity. As diamond sensors can be operated under ambient conditions, they offer potential application across a multitude of disciplines. Here we review the different existing techniques for magnetic resonance, with a focus on diamond defect spin sensors, showing their potential as versatile sensors for ultra-sensitive magnetic resonance with nanoscale spatial resolution.

  2. Towards a Compositional SPIN

    NASA Technical Reports Server (NTRS)

    Pasareanu, Corina S.; Giannakopoulou, Dimitra

    2006-01-01

    This paper discusses our initial experience with introducing automated assume-guarantee verification based on learning in the SPIN tool. We believe that compositional verification techniques such as assume-guarantee reasoning could complement the state-reduction techniques that SPIN already supports, thus increasing the size of systems that SPIN can handle. We present a "light-weight" approach to evaluating the benefits of learning-based assume-guarantee reasoning in the context of SPIN: we turn our previous implementation of learning for the LTSA tool into a main program that externally invokes SPIN to provide the model checking-related answers. Despite its performance overheads (which mandate a future implementation within SPIN itself), this approach provides accurate information about the savings in memory. We have experimented with several versions of learning-based assume guarantee reasoning, including a novel heuristic introduced here for generating component assumptions when their environment is unavailable. We illustrate the benefits of learning-based assume-guarantee reasoning in SPIN through the example of a resource arbiter for a spacecraft. Keywords: assume-guarantee reasoning, model checking, learning.

  3. Spectroscopic Properties and Potential Energy Curves of SnF +

    NASA Astrophysics Data System (ADS)

    Balasubramanian, K.; Xu, H.

    1995-06-01

    Spectroscopic properties and potential energy curves of several electronic states of SnF+ are computed using the complete active space self-consistent field (CASSCF) followed by first- and second-order configuration interaction (FOCI, SOCI) methods that include up to 1.6 million configurations. Spin-orbit effects were incorporated using the relativistic configuration interaction (RCI) method. Spectroscopic properties of several excited electronic states of SnF+ are reported, none of which is observed at present.

  4. Spectroscopic and structural investigations of the ferrous and ferric high-spin state of a ``picket—fence'' porphyrinato acetato iron complex. A refined model for the P460 center of hydroxylamine oxidoreductase

    NASA Astrophysics Data System (ADS)

    Bill, E.; Bominaar, E. L.; Ding, X.-O.; Fischer, J.; Gismelseed, A.; Nasri, H.; Trautwein, A. X.; Weiss, R.; Winkler, H.

    1992-04-01

    Mössbauer investigations were performed in the ferrous and ferric form of the ‘picket-fence’ porphyrinato acetato iron complex |Fe(CH3CO2) (TPpivP)|1-,0 at temperatures varying from 1.5 200K and in fields of 0 6.2T. The ferrous complex has an unusually large quadrupole splitting, ΔEQ=+4.25mms-1. The quadrupole splitting in the ferric species, ΔEQ=+1.1mms-1, is as normally found in ferric high-spin iron porphyrins. Spin-Hamiltonian analysis of the magnetic spectra yields zero-field parameters D=-0.9mms-1, E/D=0.33 and magnetic hyperfine parameters Ax,y=-17T, Az=-13.3T in the ferrous high-spin (S=2) complex, and D=7.5cm-1, E/D≈0 and Ax,y,z=20T in the ferric high-spin (S=5/2) species.

  5. Application of Spectroscopic Techniques (FT-IR, 13C NMR) to the analysis of humic substances in volcanic soils along an environmental gradient (Tenerife, Canary Islands, Spain)

    NASA Astrophysics Data System (ADS)

    Rodriguez Rodriguez, Antonio; María Armas Herrera, Cecilia; González Pérez, José Antonio; González-Vila, Francisco Javier; Arbelo Rodríguez, Carmen Dolores; Mora Hernández, Juan Luis; Polvillo Polo, Oliva

    2010-05-01

    Andosols and andic soils are considered as efficient C-sinks in terms of C sequestration. These soils are usually developed from volcanic materials, and are characterized by a predominance of short-range ordered minerals like allophanes, imogolite and other Fe and Al oxyhydroxides. Such materials occur commonly associated with organic compounds, thus generating highly stable organo-mineral complexes and leading to the accumulation of a high amount of organic carbon. Spectroscopic methods like FT-IR and 13C NMR are suitable for the analysis of the chemical structure of soil humic substances, and allow identifying distinct functional groups and protein, lipids, lignin, carbohydrate-derived fragments. In this work we study the structural features of four soils developed on Pleistocene basaltic lavae in Tenerife (Canary Island, Spain), distributed along an altitudinal climatic gradient. The soil sequence comprises soils with different degree of geochemical evolution and andic character, including a mineral ‘Hypersalic Solonchak' (Tabaibal de Rasca), a slightly vitric ‘Luvic Phaeozem' (Los Frailes), a degraded and shallow ‘Endoleptic, fulvic, silandic Andosol' (Siete Lomas), and a well-developed and deep ‘Fulvic, silandic, Andosol' (Ravelo). Samples of the raw soil and humic and fulvic acids isolated from the surface horizons were analyzed. The results show a low content of organic carbon in the mineral soil, the inherited humin predominating, and a very high content of humic and fulvic acids in Andosols. The FT-IR and 13C NMR spectra of the raw soil samples show a low resolution, related to interferences from mineral complexes signals, particularly in soils with lower organic carbon content. 13C NMR shows a predominance of O-alkyl carbon (derived of carbohydrates) in andic soils, whereas O-alkyl and aromatic fractions are most evident in the mineral soil. The humic acids spectra are characterized by a dominance of alkyl and aromatic fractions with a high degree

  6. Spectroscopic constants and potential energy curves for TaH

    NASA Astrophysics Data System (ADS)

    Cheng, W.; Balasubramanian, K.

    1991-09-01

    Spectroscopic constants and potential energy curves of 21 electronic states of the diatomic TaH are computed using complete active space multiconfiguration self-consistent field (CASSCF) followed by second-order configuration interaction (SOCI) calculations. In addition spin-orbit effects were included using the relativistic configuration interaction method (RCI). The ground state of TaH was found to be a 0 + state, which is a mixture of 5Δ(0 +), 5Π(0 +), 3Σ -(0 +), and 3Π(0 +). The spin-orbit effects were found to be significant for TaH. Several spectroscopic transitions are predicted for TaH none of which is observed.

  7. Monomeric and dimeric structures analysis and spectroscopic characterization of 3,5-difluorophenylboronic acid with experimental (FT-IR, FT-Raman, 1H and 13C NMR, UV) techniques and quantum chemical calculations

    NASA Astrophysics Data System (ADS)

    Karabacak, Mehmet; Kose, Etem; Atac, Ahmet; Asiri, Abdullah M.; Kurt, Mustafa

    2014-01-01

    The spectroscopic properties of 3,5-difluorophenylboronic acid (3,5-DFPBA, C6H3F2B(OH)2) were investigated by FT-IR, FT-Raman UV-Vis, 1H and 13C NMR spectroscopic techniques. FT-IR (4000-400 cm-1) and FT-Raman spectra (3500-10 cm-1) in the solid phase and 1H and 13C NMR spectra in DMSO solution were recorded. The UV spectra that dissolved in ethanol and water were recorded in the range of 200-400 nm for each solution. The structural and spectroscopic data of the molecule have been obtained for possible three conformers from DFT (B3LYP) with 6-311++G(d,p) basis set calculations. The geometry of the molecule was fully optimized, vibrational spectra were calculated and fundamental vibrations were assigned on the basis of the total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanics (SQM) method and PQS program. Hydrogen-bonded dimer of title molecule, optimized by counterpoise correction, was also studied B3LYP at the 6-311++G(d,p) level and the effects of molecular association through O-H⋯O hydrogen bonding have been discussed. 1H and 13C NMR chemical shifts were calculated by using the gauge-invariant atomic orbital (GIAO) method. The electronic properties, such as excitation energies, oscillator strength, wavelengths, HOMO and LUMO energies, were performed by time-dependent density functional theory (TD-DFT) results complements with the experimental findings. Total and partial density of state (TDOS and PDOS) and also overlap population density of state (OPDOS) diagrams analysis were presented. The effects due to the substitutions of boric acid group and halogen were investigated. The results of the calculations were applied to simulate spectra of the title compound, which show excellent agreement with observed spectra. Besides, frontier molecular orbitals (FMO), molecular electrostatic potential (MEP), nonlinear optical properties (NLO) and thermodynamic features were performed.

  8. A Comparison of FTNMR and FTIR Techniques.

    ERIC Educational Resources Information Center

    Ahn, Myong-Ku

    1989-01-01

    Nuclear magnetic resonance and infrared are two spectroscopic methods that commonly use the Fourier transform technique. Discussed are the similarities and differences in the use of the Fourier transform in these two spectroscopic techniques. (CW)

  9. Transverse Spin Diffusion

    NASA Astrophysics Data System (ADS)

    Mullin, William

    2014-05-01

    Transverse spin diffusion is a relatively new transport coefficient and a review of its history and physical basis will be presented. In NMR spin diffusion is often measured by spin echo techniques, which involve spin currents perpendicular to the direction of the magnetization, in contrast with the usual longitudinal case where the current is parallel to the magnetization. The first indication that this involved new physics was the Leggett-Rice effect (1970) in which spin waves, new spin-echo behavior, and an altered spin diffusion coefficient were predicted in liquid 3He. This effect gave the possibility of the first measurement of F1a, the parameter of the Landau Fermi-liquid theory mean-field responsible for the effect. In 1982 Lhuillier and Laloe found a transport equation very similar to the Leggett equation, but valid for highly-polarized dilute Boltzmann Bose and Fermi gases, and describing the ``identical spin rotation effect'' (ISRE), the analog of a Landau mean field. Coincidentally Bashkin and Meyerovich had also given equivalent descriptions of transport in polarized Boltzmann gases. That a mean-field effect could exists in dilute Boltzmann gases was theoretically surprising, but was confirmed experimentally. At low polarization the basic transverse diffusion constant D⊥ coincides with the longitudinal value D∥ however Meyerovich first pointed out that they could differ in highly polarized degenerate gases. Indeed detailed calculations (Jeon and Mullin) showed that, while D∥ is proportional to T-2, D⊥ approaches a constant (depending on polarization) at low T. Considerable controversy existed until experimental verification was achieved in 2004. The importance of ISRE again arose in 2008 as the basis of ``anomalous spin-state segregation'' in Duke and JILA experiments. More recently application of the ideas of transverse spin diffusion to strongly interacting Fermi gases has resulted in the observation of the diffusion constants at the quantum

  10. Determination of the spin diffusion length in germanium by spin optical orientation and electrical spin injection

    NASA Astrophysics Data System (ADS)

    Rinaldi, C.; Bertoli, S.; Asa, M.; Baldrati, L.; Manzoni, C.; Marangoni, M.; Cerullo, G.; Bianchi, M.; Sordan, R.; Bertacco, R.; Cantoni, M.

    2016-10-01

    The measurement of the spin diffusion length and/or lifetime in semiconductors is a key issue for the realisation of spintronic devices, exploiting the spin degree of freedom of carriers for storing and manipulating information. In this paper, we address such parameters in germanium (0 0 1) at room temperature (RT) by three different measurement methods. Exploiting optical spin orientation in the semiconductor and spin filtering across an insulating MgO barrier, the dependence of the resistivity on the spin of photo-excited carriers in Fe/MgO/Ge spin photodiodes (spin-PDs) was electrically detected. A spin diffusion length of 0.9  ±  0.2 µm was obtained by fitting the photon energy dependence of the spin signal by a mathematical model. Electrical techniques, comprising non-local four-terminal and Hanle measurements performed on CoFeB/MgO/Ge lateral devices, led to spin diffusion lengths of 1.3  ±  0.2 µm and 1.3  ±  0.08 µm, respectively. Despite minor differences due to experimental details, the order of magnitude of the spin diffusion length is the same for the three techniques. Although standard electrical methods are the most employed in semiconductor spintronics for spin diffusion length measurements, here we demonstrate optical spin orientation as a viable alternative for the determination of the spin diffusion length in semiconductors allowing for optical spin orientation.

  11. NMR in rotating magnetic fields: Magic angle field spinning

    SciTech Connect

    Sakellariou, D.; Meriles, C.; Martin, R.; Pines, A.

    2004-09-10

    Magic angle sample spinning has been one of the cornerstones in high-resolution solid state NMR. Spinning frequencies nowadays have increased by at least one order of magnitude over the ones used in the first experiments and the technique has gained tremendous popularity. It is currently a routine procedure in solid-state NMR, high-resolution liquid-state NMR and solid-state MRI. The technique enhances the spectral resolution by averaging away rank 2 anisotropic spin interactions thereby producing isotropic-like spectra with resolved chemical shifts and scalar couplings. Andrew proposed that it should be possible to induce similar effects in a static sample if the direction of the magnetic field is varied, e.g., magic-angle rotation of the B0 field (B0-MAS) and this has been recently demonstrated using electromagnetic field rotation. Here we discuss on the possibilities to perform field rotation using alternative hardware, together with spectroscopic methods to recover isotropic resolution even in cases where the field is not rotating at the magic angle. Extension to higher magnetic fields would be beneficial in situations where the physical manipulation of the sample is inconvenient or impossible. Such situations occur often in materials or biomedical samples where ''ex-situ'' NMR spectroscopy and imaging analysis is needed.

  12. Arterial Spin-Labeled Perfusion Combined with Segmentation Techniques to Evaluate Cerebral Blood Flow in White and Gray Matter of Children with Sickle Cell Anemia

    PubMed Central

    Helton, Kathleen J.; Paydar, Amir; Glass, John; Weirich, Eric M.; Hankins, Jane; Li, Chin-Shang; Smeltzer, Matthew P.; Wang, Winfred C.; Ware, Russell E.; Ogg, Robert J.

    2015-01-01

    Background Changes in cerebral perfusion are an important feature of the pathophysiology of sickle cell anemia (SCA); cerebrovascular ischemia occurs frequently and leads to neurocognitive deficits, silent infarcts, and overt stroke. Non-invasive MRI methods to measure cerebral blood flow (CBF) by arterial spin labeling (ASL) afford new opportunities to characterize disease- and therapy-induced changes in cerebral hemodynamics in patients with SCA. Recent studies have documented elevated gray matter (GM) CBF in untreated children with SCA, but no measurements of white matter (WM) CBF have been reported. Procedures Pulsed ASL with automated brain image segmentation-classification techniques were used to determine the CBF in GM, WM, and abnormal white matter (ABWM) of 21 children with SCA, 18 of whom were receiving hydroxyurea therapy. Results GM and WM CBF were highly associated (R2 =.76, p< 0.0001) and the GM to WM CBF ratio was 1.6 (95% confidence interval: 1.43-1.83). Global GM CBF in our treated cohort was 87 ± 24 mL/min/100 g, a value lower than previously reported in untreated patients with SCA. CBF was elevated in normal appearing WM (43 ± 14 mL/min/100 g) but decreased in ABWM (6 ± 12 mL/min/100 g), compared to published normal pediatric controls. Hemispheric asymmetry in CBF was noted in most patients. Conclusions These perfusion measurements suggest that hydroxyurea may normalize GM CBF in children with SCA, but altered perfusion in WM may persist. This novel combined approach for CBF quantification will facilitate prospective studies of cerebral vasculopathy in SCA, particularly regarding the effects of treatments such as hydroxyurea. PMID:18937311

  13. Chelating fibers prepared with a wet spinning technique using a mixture of a viscose solution and a polymer ligand for the separation of metal ions in an aqueous solution.

    PubMed

    Kagaya, Shigehiro; Miyazaki, Hiroyuki; Inoue, Yoshinori; Kato, Toshifumi; Yanai, Hideyuki; Kamichatani, Waka; Kajiwara, Takehiro; Saito, Mitsuru; Tohda, Koji

    2012-02-15

    Chelating fibers containing polymer ligands such as carboxymethylated polyallylamine, carboxymethylated polyethyleneimine, and a copolymer of diallylamine hydrochloride/maleic acid were prepared with a wet spinning technique using mixtures of a viscose solution and the polymer ligands. The chelating fibers obtained effectively adsorbed various metal ions, including Cd(II), Co(II), Cr(III), Cu(II), Fe(III), Mn(II), Ni(II), Pb(II), Ti(IV), and Zn(II). The metal ions adsorbed could be readily desorbed using 0.1 or 0.5 mol L(-1) HNO(3). The chelating fiber containing carboxymethylated polyallylamine was available for the separation of some metal ions in synthetic wastewater containing a large amount of Na(2)SO(4). The wet spinning technique using a solution containing a base polymer and a polymer ligand was quite simple and effective and would be applicable for preparing various chelating fibers.

  14. Novel, near-infrared spectroscopic, label-free, techniques to assess bone abnormalities such as Paget's disease, osteoporosis and bone fractures

    NASA Astrophysics Data System (ADS)

    Sordillo, Diana C.; Sordillo, Laura A.; Shi, Lingyan; Budansky, Yury; Sordillo, Peter P.; Alfano, Robert R.

    2015-02-01

    Near- infrared (NIR) light with wavelengths from 650 nm to 950 nm (known as the first NIR window) has conventionally been used as a non-invasive technique that can reach deeper penetration depths through media than light at shorter wavelengths. Recently, several novel, NIR, label-free, techniques have been developed to assess Paget's disease of bone, osteoporosis and bone microfractures. We designed a Bone Optical Analyzer (BOA) which utilizes the first window to measure changes of Hb and HbO2. Paget's disease is marked by an increase in vascularization in bones, and this device can enable easy diagnosis and more frequent monitoring of the patient's condition, without exposing him to a high cumulative dose of radiation. We have also used inverse imaging algorithms to reconstruct 2D and 3D maps of the bone's structure. This device could be used to assess diseases such as osteoporosis. Using 800 nm femtosecond excitation with two-photon (2P) microscopy, we acquired 2PM images of the periosteum and spatial frequency spectra (based on emission of collagen) from the periosteal regions. This technique can provide information on the structure of the periosteum and can detect abnormalities which may be an indication of disease. Most recently, we showed that longer NIR wavelengths in the second and third NIR windows (1100 nm-1350 nm, 1600 nm-1870 nm), could be used to image bone microfractures. Use of NIR light could allow for repeated studies in patients with diseases such as Paget's and osteoporosis quickly and non-invasively, and could impact the current management for these diseases.

  15. Spin forming development

    SciTech Connect

    Gates, W.G.

    1982-05-01

    Bendix product applications require the capability of fabricating heavy gage, high strength materials. Five commercial sources have been identified that have the capability of spin forming metal thicknesses greater than 9.5 mm and four equiment manufacturers produce machines with this capability. Twelve assemblies selected as candidates for spin forming applications require spin forming of titanium, 250 maraging steel, 17-4 pH stainless steel, Nitronic 40 steel, 304 L stainless steel, and 6061 aluminum. Twelve parts have been cold spin formed from a 250 maraging steel 8.1 mm wall thickness machine preform, and six have been hot spin formed directly from 31.8-mm-thick flat plate. Thirty-three Ti-6Al-4V titanium alloy parts and 26 17-4 pH stainless steel parts have been hot spin formed directly from 31.8-mm-thick plate. Hot spin forming directly from plate has demonstrated the feasibility and favorable economics of this fabrication technique for Bendix applications.

  16. Characterization of spin relaxation anisotropy in Co using spin pumping

    NASA Astrophysics Data System (ADS)

    Li, Yi; Cao, Wei; Bailey, W. E.

    2016-11-01

    Ferromagnets are believed to exhibit strongly anisotropic spin relaxation, with relaxation lengths for spin longitudinal to the magnetization significantly longer than those for spin transverse to the magnetization. Here, we characterize the anisotropy of spin relaxation in Co using the spin pumping contribution to Gilbert damping in noncollinearly magnetized Py1 -xCux /Cu/Co trilayer structures. The static magnetization angle between Py1 -xCux and Co, adjusted under field bias perpendicular to film planes, controls the projections of longitudinal and transverse spin current pumped from Py1 -xCux into Co. We find nearly isotropic absorption of pure spin current in Co using this technique; fits to a diffusive transport model yield the longitudinal spin relaxation length <2 nm in Co. The longitudinal spin relaxation lengths found are an order of magnitude smaller than those determined by current-perpendicular-to-planes giant magnetoresistance measurements, but comparable with transverse spin relaxation lengths in Co determined by spin pumping.

  17. Spectroscopic optical coherence elastography.

    PubMed

    Adie, Steven G; Liang, Xing; Kennedy, Brendan F; John, Renu; Sampson, David D; Boppart, Stephen A

    2010-12-06

    We present an optical technique to image the frequency-dependent complex mechanical response of a viscoelastic sample. Three-dimensional hyperspectral data, comprising two-dimensional B-mode images and a third dimension corresponding to vibration frequency, were acquired from samples undergoing external mechanical excitation in the audio-frequency range. We describe the optical coherence tomography (OCT) signal when vibration is applied to a sample and detail the processing and acquisition techniques used to extract the local complex mechanical response from three-dimensional data that, due to a wide range of vibration frequencies, possess a wide range of sample velocities. We demonstrate frequency-dependent contrast of the displacement amplitude and phase of a silicone phantom containing inclusions of higher stiffness. Measurements of an ex vivo tumor margin demonstrate distinct spectra between adipose and tumor regions, and images of displacement amplitude and phase demonstrated spatially-resolved contrast. Contrast was also observed in displacement amplitude and phase images of a rat muscle sample. These results represent the first demonstration of mechanical spectroscopy based on B-mode OCT imaging. Spectroscopic optical coherence elastography (S-OCE) provides a high-resolution imaging capability for the detection of tissue pathologies that are characterized by a frequency-dependent viscoelastic response.

  18. Thermal inkjet application in the preparation of oral dosage forms: dispensing of prednisolone solutions and polymorphic characterization by solid-state spectroscopic techniques.

    PubMed

    Meléndez, Peter A; Kane, Kevin M; Ashvar, Claudine S; Albrecht, Mary; Smith, Pamela A

    2008-07-01

    The utility of thermal inkjet (TIJ) technology for preparing solid dosage forms of drugs was examined. Solutions of prednisolone in a solvent mixture of ethanol, water, and glycerol (80/17/3 by volume) were dispensed onto poly(tetrafluoroethylene)-coated fiberglass films using TIJ cartridges and a personal printer and using a micropipette for comparison. The post-dried, TIJ-dispensed samples were shown to contain a mixture of prednisolone Forms I and III based on PXRD analyses that were confirmed by Raman analyses. The starting commercial material was determined to be Form I. Samples prepared by dispensing the solution from a micropipette initially showed only Form I; subsequent Raman mapping of these samples revealed the presence of two polymorphs. Raman mapping of the TIJ-dispensed samples also showed both polymorphs. The results indicate that the solvent mixture used in the dispensing solution combined with the thermal treatment of the samples after dispensing were likely the primary reason for the generation of the two polymorphs. The advantages of using a multidisciplinary approach to characterize drug delivery systems are demonstrated using solid state mapping techniques. Both PXRD and Raman spectroscopy were needed to fully characterize the samples. Finally, this report clarifies prednisolone's polymorphic nomenclature existent in the scientific literature.

  19. Domain-specific interactions between MLN8237 and human serum albumin estimated by STD and WaterLOGSY NMR, ITC, spectroscopic, and docking techniques.

    PubMed

    Yang, Hongqin; Liu, Jiuyang; Huang, Yanmei; Gao, Rui; Tang, Bin; Li, Shanshan; He, Jiawei; Li, Hui

    2017-03-30

    Alisertib (MLN8237) is an orally administered inhibitor of Aurora A kinase. This small-molecule inhibitor is under clinical or pre-clinical phase for the treatment of advanced malignancies. The present study provides a detailed characterization of the interaction of MLN8237 with a drug transport protein called human serum albumin (HSA). STD and WaterLOGSY nuclear magnetic resonance (NMR)-binding studies were conducted first to confirm the binding of MLN8237 to HSA. In the ligand orientation assay, the binding sites of MLN8237 were validated through two site-specific spy molecules (warfarin sodium and ibuprofen, which are two known site-selective probes) by using STD and WaterLOGSY NMR competition techniques. These competition experiments demonstrate that both spy molecules do not compete with MLN8237 for the specific binding site. The AutoDock-based blind docking study recognizes the hydrophobic subdomain IB of the protein as the probable binding site for MLN8237. Thermodynamic investigations by isothermal titration calorimetry (ITC) reveal that the non-covalent interaction between MLN8237 and HSA (binding constant was approximately 10(5) M(-1)) is driven mainly by favorable entropy and unfavorable enthalpy. In addition, synchronous fluorescence, circular dichroism (CD), and 3D fluorescence spectroscopy suggest that MLN8237 may induce conformational changes in HSA.

  20. In vitro studies on the behavior of salmeterol xinafoate and its interaction with calf thymus DNA by multi-spectroscopic techniques

    NASA Astrophysics Data System (ADS)

    Zhao, Tingting; Bi, Shuyun; Wang, Yu; Wang, Tianjiao; Pang, Bo; Gu, Tingting

    2014-11-01

    The salmeterol xinafoate (SX) binding to calf thymus DNA in vitro was explored by fluorescence, resonance light scattering (RLS), UV-vis absorption, as well as viscometry, ionic strength effect and DNA melting techniques. It was found that SX could bind to DNA weakly, and the binding constants (Ka) were determined as 8.52 × 103, 8.31 × 103 and 6.14 × 103 L mol-1 at 18, 28 and 38 °C respectively. When bound to DNA, SX showed fluorescence quenching in the fluorescence spectra and hyperchromic effect in the absorption spectra. Stern-Volmer plots revealed that the quenching of fluorescence of SX by DNA was a static quenching. Furthermore, the relative viscosity and melting temperature of DNA solution were hardly influenced by SX, while the fluorescence intensity of SX-DNA was observed to decrease with the increasing ionic strength of system. Also, the binding constant between SX and double stranded DNA (dsDNA) was much weaker than that between SX and single stranded DNA (ssDNA). All these results suggested that the binding mode of SX to DNA should be groove binding. The obtained thermodynamic parameters indicated that electrostatic force might play a predominant role in SX binding to DNA. The quantum yield (φ) of SX was measured as 0.13 using comparative method. Based on the Förster resonance energy transfer theory (FRET), the binding distance (r0) between the acceptor and donor was calculated as 4.10 nm.

  1. Domain-specific interactions between MLN8237 and human serum albumin estimated by STD and WaterLOGSY NMR, ITC, spectroscopic, and docking techniques

    PubMed Central

    Yang, Hongqin; Liu, Jiuyang; Huang, Yanmei; Gao, Rui; Tang, Bin; Li, Shanshan; He, Jiawei; Li, Hui

    2017-01-01

    Alisertib (MLN8237) is an orally administered inhibitor of Aurora A kinase. This small-molecule inhibitor is under clinical or pre-clinical phase for the treatment of advanced malignancies. The present study provides a detailed characterization of the interaction of MLN8237 with a drug transport protein called human serum albumin (HSA). STD and WaterLOGSY nuclear magnetic resonance (NMR)-binding studies were conducted first to confirm the binding of MLN8237 to HSA. In the ligand orientation assay, the binding sites of MLN8237 were validated through two site-specific spy molecules (warfarin sodium and ibuprofen, which are two known site-selective probes) by using STD and WaterLOGSY NMR competition techniques. These competition experiments demonstrate that both spy molecules do not compete with MLN8237 for the specific binding site. The AutoDock-based blind docking study recognizes the hydrophobic subdomain IB of the protein as the probable binding site for MLN8237. Thermodynamic investigations by isothermal titration calorimetry (ITC) reveal that the non-covalent interaction between MLN8237 and HSA (binding constant was approximately 105 M−1) is driven mainly by favorable entropy and unfavorable enthalpy. In addition, synchronous fluorescence, circular dichroism (CD), and 3D fluorescence spectroscopy suggest that MLN8237 may induce conformational changes in HSA. PMID:28358124

  2. Spin-orbit-coupling-induced spin squeezing in three-component Bose gases

    NASA Astrophysics Data System (ADS)

    Huang, X. Y.; Sun, F. X.; Zhang, W.; He, Q. Y.; Sun, C. P.

    2017-01-01

    We observe spin squeezing in three-component Bose gases where all three hyperfine states are coupled by synthetic spin-orbit coupling. This phenomenon is a direct consequence of spin-orbit coupling, as can be seen clearly from an effective spin Hamiltonian. By solving this effective model analytically with the aid of a Holstein-Primakoff transformation for a spin-1 system in the low excitation limit, we conclude that the spin-nematic squeezing, a category of spin squeezing existing exclusively in large spin systems, is enhanced with increasing spin-orbit coupling intensity and effective Zeeman field, which correspond to Rabi frequency ΩR and two-photon detuning δ within the Raman scheme for synthetic spin-orbit coupling, respectively. These trends of dependence are in clear contrast to spin-orbit-coupling-induced spin squeezing in spin-1/2 systems. We also analyze the effects of harmonic trap and interparticle interaction with realistic experimental parameters numerically, and find that a strong harmonic trap favors spin-nematic squeezing. We further show spin-nematic squeezing can be interpreted as two-mode entanglement or two-spin squeezing at low excitation. Our findings can be observed in 87Rb gases with existing techniques of synthetic spin-orbit coupling and spin-selective imaging.

  3. Optical Spectroscopic Monitoring of Parachute Yarn Aging

    SciTech Connect

    Tallant, D.R.; Garcia, M.J.; Simpson, R.L.; Behr, V.L.; Whinery, L.D.; Peng, L.W.

    1999-04-01

    Optical spectroscopic techniques were evaluated as nondestructive monitors of the aging of parachutes in nuclear weapons. We analyzed thermally aged samples of nylon and Kevlar webbing by photoluminescence spectroscopy and reflection spectroscopy. Infrared analysis was also performed to help understand the degradation mechanisms of the polymer materials in the webbing. The photoluminescence and reflection spectra were analyzed by chemometric data treatment techniques to see if aged-induced changes in the spectra correlated to changes in measured tensile strength. A correlation was found between the shapes of the photoluminescent bands and the measured tensile strengths. Photoluminescent spectra can be used to predict the tensile strengths of nylon and Kevlar webbing with sufficient accuracy to categorize the webbing sample as above rated tensile strength, marginal or below rated tensile strength. The instrumentation required to perform the optical spectroscopic measurement can be made rugged, compact and portable. Thus, optical spectroscopic techniques offer a means for nondestructive field monitoring of parachutes in the enduring stockpile/

  4. Trans fat labeling and levels in U.S. foods: assessment of gas chromatographic and infrared spectroscopic techniques for regulatory compliance.

    PubMed

    Mossoba, Magdi M; Moss, Julie; Kramer, John K G

    2009-01-01

    Trans fatty acids are found in a variety of foods like dairy and meat products, but the major dietary sources are products that contain commercially hydrogenated fats. There has been a renewed need for accurate analytical methods for the quantitation of total trans fat since mandatory requirements to declare the amount of trans fat present in food products and dietary supplements were issued in many countries. Official capillary GC and IR methodologies are the two most common validated methods used to identify and quantify trans fatty acids for regulatory compliance. The present article provides a comprehensive discussion of the GC and IR techniques, including the latest attenuated total reflection (ATR)-FTIR methodology called the negative second derivative ATR-FTIR procedure, which is currently being validated in an international collaborative study. The identification and quantitation of trans fatty acid isomers by GC is reviewed and an alternative GC method is proposed using two temperature programs and combining their results; this proposed method deals more effectively with the resolution of large numbers of geometric and positional monoene, diene, and triene fatty acid isomers present in ruminant fats. In addition, the different methylation procedures that affect quantitative conversion to fatty acid methyl esters are reviewed. There is also a lack of commercial chromatographic standards for many trans fatty acid isomers. This review points to potential sources of interferences in the FTIR determination that may lead to inaccurate results, particularly at low trans levels. The presence of high levels of saturated fats may lead to interferences in the FTIR spectra observed for trans triacylglycerols (TAGs). TAGs require no derivatization, but have to be melted prior to IR measurement. While GC is currently the method of choice, ATR-FTIR spectroscopy is a viable, rapid alternative, and a complementary method to GC for a more rapid determination of total trans

  5. Characterization of the deterioration of bone black in the 17 th century Oranjezaal paintings using electron-microscopic and micro-spectroscopic imaging techniques

    NASA Astrophysics Data System (ADS)

    van Loon, Annelies; Boon, Jaap J.

    2004-10-01

    A whitish deterioration product was observed on the dark paint in a number of large-scale oil paintings that are part of the Oranjezaal interior decoration in the Royal Palace Huis ten Bosch (The Hague). The whitened areas of a painting by Pieter Soutman dating from 1648 were micro-sampled and compared with "healthy" black paint using different analytical imaging techniques. The dark paint was identified as bone black in linseed oil with a lead drier added. Microscopic images of the cross-section revealed a white top layer of 10-20 μm in the black paint layer. Imaging the cross-section surface with scanning electron microscopy with energy dispersive X-ray analysis (SEM-EDX) and specular reflection Fourier transform infrared (FTIR) showed homogeneous distributions of phosphate, phosphorus and calcium over the black and the white degraded bone black. X-ray diffraction (XRD) showed the presence of calcium phosphate hydrate (Ca 3(PO 4) 2· xH 2O), monetite (CaHPO 4) with possibly some poorly crystalline or amorphous hydroxyapatite (Ca 5(OH)(PO 4) 3). The EDX maps of lead and carbon, however, showed some discontinuity between the degraded and non-degraded bone black. There was an increase in the lead concentration in the white top layer, and a slight decrease of carbon. Transmission FTIR demonstrated that aromatic network polymers from the carbon black are markedly diminished in the white deterioration product. It is proposed that the carbonized organic matter in the bone black is vulnerable to photo bleaching in the presence of a lead catalyst under these circumstances.

  6. Spectroscopic characterization of III-V semiconductor nanomaterials

    NASA Astrophysics Data System (ADS)

    Crankshaw, Shanna Marie

    through a novel spectroscopic technique first formulated for the rather different purpose of dispersion engineering for slow-light schemes. The frequency-resolved technique combined with the unusual (110) quantum wells in a furthermore atypical waveguide experimental geometry has revealed fascinating behavior of electron spin splitting which points to the possibility of optically orienting electron spins with linearly polarized light---an experimental result supporting a theoretical description of the phenomenon itself only a few years old. Lastly, to explore a space of further-restricted dimensionality, the final chapters describe InP semiconductor nanowires with dimensions small enough to be considered truly one-dimensional. Like the bulk GaAs of the first few chapters, the InP nanowires here crystallize in a wurtzite structure. In the InP nanowire case, though, the experimental techniques explored for characterization are temperature-dependent time-integrated photoluminescence at the single-wire level (including samples with InAsP insertions) and time-resolved photoluminescence at the ensemble level. The carrier dynamics revealed through these time-resolved studies are the first of their kind for wurtzite InP nanowires. The chapters are thus ordered as a progression from three (bulk), to two (quantum well), to one (nanowire), to zero dimensions (axially-structured nanowire), with the uniting theme the emphasis on connecting the semiconductor nanomaterials' crystallinity to its exhibited properties by relevant experimental spectroscopic techniques, whether these are standard methods or effectively invented for the case at hand.

  7. A new combined nuclear magnetic resonance and Raman spectroscopic probe applied to in situ investigations of catalysts and catalytic processes

    NASA Astrophysics Data System (ADS)

    Camp, Jules C. J.; Mantle, Michael D.; York, Andrew P. E.; McGregor, James

    2014-06-01

    Both Raman and nuclear magnetic resonance (NMR) spectroscopies are valuable analytical techniques capable of providing mechanistic information and thereby providing insights into chemical processes, including catalytic reactions. Since both techniques are chemically sensitive, they yield not only structural information but also quantitative analysis. In this work, for the first time, the combination of the two techniques in a single experimental apparatus is reported. This entailed the design of a new experimental probe capable of recording simultaneous measurements on the same sample and/or system of interest. The individual datasets acquired by each spectroscopic method are compared to their unmodified, stand-alone equivalents on a single sample as a means to benchmark this novel piece of equipment. The application towards monitoring reaction progress is demonstrated through the evolution of the homogeneous catalysed metathesis of 1-hexene, with both experimental techniques able to detect reactant consumption and product evolution. This is extended by inclusion of magic angle spinning (MAS) NMR capabilities with a custom made MAS 7 mm rotor capable of spinning speeds up to 1600 Hz, quantified by analysis of the spinning sidebands of a sample of KBr. The value of this is demonstrated through an application involving heterogeneous catalysis, namely the metathesis of 2-pentene and ethene. This provides the added benefit of being able to monitor both the reaction progress (by NMR spectroscopy) and also the structure of the catalyst (by Raman spectroscopy) on the very same sample, facilitating the development of structure-performance relationships.

  8. Spin noise in the anisotropic central spin model

    NASA Astrophysics Data System (ADS)

    Hackmann, Johannes; Anders, Frithjof B.

    2014-01-01

    Spin-noise measurements can serve as a direct probe for the microscopic decoherence mechanism of an electronic spin in semiconductor quantum dots (QDs). We have calculated the spin-noise spectrum in the anisotropic central spin model using a Chebyshev expansion technique which exactly accounts for the dynamics up to an arbitrary long but fixed time in a finite-size system. In the isotropic case, describing QD charge with a single electron, the short-time dynamics is in good agreement with quasistatic approximations for the thermodynamic limit. The spin-noise spectrum, however, shows strong deviations at low frequencies with a power-law behavior of ω-3/4 corresponding to a t-1/4 decay at intermediate and long times. In the Ising limit, applicable to QDs with heavy-hole spins, the spin-noise spectrum exhibits a threshold behavior of (ω-ωL)-1/2 above the Larmor frequency ωL=gμBB. In the generic anisotropic central spin model we have found a crossover from a Gaussian type of spin-noise spectrum to a more Ising-type spectrum with increasing anisotropy in a finite magnetic field. In order to make contact with experiments, we present ensemble averaged spin-noise spectra for QD ensembles charged with single electrons or holes. The Gaussian-type noise spectrum evolves to a more Lorentzian shape spectrum with increasing spread of characteristic time scales and g factors of the individual QDs.

  9. Development of a THz spectroscopic imaging system.

    PubMed

    Usami, M; Iwamoto, T; Fukasawa, R; Tani, M; Watanabe, M; Sakai, K

    2002-11-07

    We have developed a real-time THz imaging system based on the two-dimensional (2D) electro-optic (EO) sampling technique. Employing the 2D EO-sampling technique, we can obtain THz images using a CCD camera at a video rate of up to 30 frames per second. A spatial resolution of 1.4 mm was achieved. This resolution was reasonably close to the theoretical limit determined by diffraction. We observed not only static objects but also moving ones. To acquire spectroscopic information, time-domain images were collected. By processing these images on a computer, we can obtain spectroscopic images. Spectroscopy for silicon wafers was demonstrated.

  10. Quantum limited heterodyne detection of spin noise

    NASA Astrophysics Data System (ADS)

    Cronenberger, S.; Scalbert, D.

    2016-09-01

    Spin noise spectroscopy is a powerful technique for studying spin relaxation in semiconductors. In this article, we propose an extension of this technique based on optical heterodyne detection of spin noise, which provides several key advantages compared to conventional spin noise spectroscopy: detection of high frequency spin noise not limited by detector bandwidth or sampling rates of digitizers, quantum limited sensitivity even in case of very weak probe power, and possible amplification of the spin noise signal. Heterodyne detection of spin noise is demonstrated on insulating n-doped GaAs. From measurements of spin noise spectra up to 0.4 Tesla, we determined the distribution of g-factors, Δg/g = 0.49%.

  11. Structure of odd-odd 136La at high spin

    NASA Astrophysics Data System (ADS)

    Bhattacharjee, Tumpa; Chanda, Somen; Bhattacharyya, Sarmishtha; Basu, Swapan Kumar; Bhowmik, R. K.; Muralithar, S.; Singh, R. P.; Pattabiraman, N. S.; Ghugre, S. S.; Datta Pramanik, U.; Bhattacharya, S.

    2005-04-01

    The high spin states in the N=79 odd-odd 136La nucleus have been investigated by in-beam γ-spectroscopic techniques following the 130Te( 11B, 5 n) 136La reaction at E=52 MeV using an array, consisting of eight Compton-suppressed clover germanium detectors. Thirty nine new γ rays have been assigned to 136La on the basis of γ ray singles and γγ-coincidence data. The level scheme of 136La has been extended above the known 115 ms isomer upto an excitation energy of 4.6 MeV and spin 18 ℏ. Thirty one new levels have been proposed and spin-parity assignments for most of the newly proposed levels have been made on the basis of the deduced asymmetry ratios and polarisation information for the de-exciting transitions. The observed positive parity yrast band has been compared with the theoretical calculation, done within the framework of particle rotor coupling model (PRM) where the two odd quasi-particles are coupled to an axially symmetric core. The level structure has been discussed in the light of the known systematics of the neighbouring N=79 isotonic nuclei.

  12. Spin-asymmetric Josephson plasma oscillations

    NASA Astrophysics Data System (ADS)

    Kreula, J. M.; Valtolina, G.; Törmä, P.

    2017-01-01

    The spin-asymmetric Josephson effect is a proposed quantum-coherent tunneling phenomenon where Cooper-paired fermionic spin-1/2 particles, which are subjected to spin-dependent potentials across a Josephson junction, undergo frequency-synchronized alternating-current Josephson oscillations with spin-dependent amplitudes. Here, in line with present-day techniques in ultracold Fermi gas setups, we consider the regime of small Josephson oscillations and show that the Josephson plasma oscillation amplitude becomes spin dependent in the presence of spin-dependent potentials, while the Josephson plasma frequency is the same for both spin components. Detecting these spin-dependent Josephson plasma oscillations provides a possible means to establish the yet-unobserved spin-asymmetric Josephson effect with ultracold Fermi gases using existing experimental tools.

  13. Spin-Charge Conversion Phenomena in Germanium

    NASA Astrophysics Data System (ADS)

    Oyarzún, Simón; Rortais, Fabien; Rojas-Sánchez, Juan-Carlos; Bottegoni, Federico; Laczkowski, Piotr; Vergnaud, Céline; Pouget, Stéphanie; Okuno, Hanako; Vila, Laurent; Attané, Jean-Philippe; Beigné, Cyrille; Marty, Alain; Gambarelli, Serge; Ducruet, Clarisse; Widiez, Julie; George, Jean-Marie; Jaffrès, Henri; Jamet, Matthieu

    2017-01-01

    The spin-orbit coupling relating the electron spin and momentum allows for spin generation, detection and manipulation. It thus fulfils the three basic functions of the spin field-effect-transistor made of semiconductors. In this paper, we review our recent results on spin-charge conversion in bulk germanium and at the Ge(111) surface. We used the spin pumping technique to generate pure spin currents to be injected into bulk germanium and at the Fe/Ge(111) interface. The mechanism for spin-charge conversion in bulk germanium is the spin Hall effect and we could experimentally determine the spin Hall angle θSHE, i.e., the spin-charge conversion efficiency, in heavily doped n-type and p-type germanium. We found very small values at room temperature: θSHE ≈ (1-2) × 10-3 in n-Ge and θSHE ≈ (6-7) × 10-4 in p-Ge. Moreover, we pointed out the essential role of spin dependent scattering on ionized impurities in the spin Hall effect mechanism. We concluded that the spin Hall effect in bulk germanium is too weak to produce large spin currents, whereas a large Rashba effect (>100 meV) at Ge(111) surfaces covered with heavy metals could generate spin polarized currents. We could indeed demonstrate a giant spin-to-charge conversion in metallic states at the Fe/Ge(111) interface due to the Rashba coupling. We generated very large charge currents by direct spin pumping into the interface states from 20 K to room temperature. By this, we raise a new paradigm: the possibility to use the spin-orbit coupling for the development of the spin-field-effect-transistor.

  14. A Spectroscopic-Based Laboratory Experiment for Protein Conformational Studies

    ERIC Educational Resources Information Center

    Ramos, Carlos Henrique I.

    2004-01-01

    This article describes a practical experiment for teaching basic spectroscopic techniques to introduce the topic of protein conformational change to students in the field of molecular biology, biochemistry, or structural biology. The spectroscopic methods employed in the experiment are absorbance, for protein concentration measurements, and…

  15. γ-ray decay from neutron-bound and unbound states in 95Mo and a novel technique for spin determination

    SciTech Connect

    Wiedeking, M.; Krticka, M.; Bernstein, L. A.; Allmond, James M.; Basunia, M. S.; Bleuel, D. L.; Burke, J. T.; Daub, B. H.; Fallon, P.; Firestone, R. B.; Goldblum, B. L.; Hatarik, R.; Lake, P. T.; Larsen, A. C.; Lee, I. -Y.; Lesher, S. R.; Paschalis, S.; Petri, M.; Phair, L.; Scielzo, N. D.; Volya, A.

    2016-02-01

    The emission of γ rays from neutron-bound and neutron-unbound states in 95Mo, populated in the 94Mo(d,p) reaction, has been investigated. Charged particles and γ radiation were detected with arrays of annular silicon and Clover-type high-purity Germanium detectors, respectively. Utilizing p-γ and p-γ-γ coincidences, the 95Mo level scheme was greatly enhanced with 102 new transitions and 43 new states. It agrees well with shell model calculations for excitation energies below ≈2 MeV. From p-γ coincidence data, a new method for the determination of spins of discrete levels is proposed. The method exploits the suppression of high-angular momentum neutron emission from levels with high spins populated in the (d,p) reaction above the neutron separation energy. As a result, spins for almost all 95Mo levels below 2 MeV (and for a few levels above) have been determined with this method.

  16. γ-ray decay from neutron-bound and unbound states in 95Mo and a novel technique for spin determination

    DOE PAGES

    Wiedeking, M.; Krticka, M.; Bernstein, L. A.; ...

    2016-02-01

    The emission of γ rays from neutron-bound and neutron-unbound states in 95Mo, populated in the 94Mo(d,p) reaction, has been investigated. Charged particles and γ radiation were detected with arrays of annular silicon and Clover-type high-purity Germanium detectors, respectively. Utilizing p-γ and p-γ-γ coincidences, the 95Mo level scheme was greatly enhanced with 102 new transitions and 43 new states. It agrees well with shell model calculations for excitation energies below ≈2 MeV. From p-γ coincidence data, a new method for the determination of spins of discrete levels is proposed. The method exploits the suppression of high-angular momentum neutron emission from levelsmore » with high spins populated in the (d,p) reaction above the neutron separation energy. As a result, spins for almost all 95Mo levels below 2 MeV (and for a few levels above) have been determined with this method.« less

  17. Paramagnetic spin seebeck effect.

    PubMed

    Wu, Stephen M; Pearson, John E; Bhattacharya, Anand

    2015-05-08

    We report the observation of the longitudinal spin Seebeck effect in paramagnetic insulators. By using a microscale on-chip local heater, we generate a large thermal gradient confined to the chip surface without a large increase in the total sample temperature. Using this technique at low temperatures (<20  K), we resolve the paramagnetic spin Seebeck effect in the insulating paramagnets Gd3Ga5O12 (gadolinium gallium garnet) and DyScO3 (DSO), using either W or Pt as the spin detector layer. By taking advantage of the strong magnetocrystalline anisotropy of DSO, we eliminate contributions from the Nernst effect in W or Pt, which produces a phenomenologically similar signal.

  18. Paramagnetic Spin Seebeck Effect

    NASA Astrophysics Data System (ADS)

    Wu, Stephen M.; Pearson, John E.; Bhattacharya, Anand

    2015-05-01

    We report the observation of the longitudinal spin Seebeck effect in paramagnetic insulators. By using a microscale on-chip local heater, we generate a large thermal gradient confined to the chip surface without a large increase in the total sample temperature. Using this technique at low temperatures (<20 K ), we resolve the paramagnetic spin Seebeck effect in the insulating paramagnets Gd3Ga5O12 (gadolinium gallium garnet) and DyScO3 (DSO), using either W or Pt as the spin detector layer. By taking advantage of the strong magnetocrystalline anisotropy of DSO, we eliminate contributions from the Nernst effect in W or Pt, which produces a phenomenologically similar signal.

  19. Spectroscopic study in Z-pinch discharge

    SciTech Connect

    Garamoon, A.A.; Saudy, A.H.; Shark, W.

    1995-12-31

    The temporal variation of the emitted line intensity has been investigated, and thus an important information about the dynamic ionization stages in the Z-pinch discharge has been studied. Also the electron temperature Te, has been deduced by using a spectroscopic technique.

  20. Overview of spin physics

    SciTech Connect

    Yokosawa, A.

    1992-12-23

    Spin physics activities at medium and high energies became significantly active when polarized targets and polarized beams became accessible for hadron-hadron scattering experiments. My overview of spin physics will be inclined to the study of strong interaction using facilities at Argonne ZGS, Brookhaven AGS (including RHIC), CERN, Fermilab, LAMPF, an SATURNE. In 1960 accelerator physicists had already been convinced that the ZGS could be unique in accelerating a polarized beam; polarized beams were being accelerated through linear accelerators elsewhere at that time. However, there was much concern about going ahead with the construction of a polarized beam because (i) the source intensity was not high enough to accelerate in the accelerator, (ii) the use of the accelerator would be limited to only polarized-beam physics, that is, proton-proton interaction, and (iii) p-p elastic scattering was not the most popular topic in high-energy physics. In fact, within spin physics, [pi]-nucleon physics looked attractive, since the determination of spin and parity of possible [pi]p resonances attracted much attention. To proceed we needed more data beside total cross sections and elastic differential cross sections; measurements of polarization and other parameters were urgently needed. Polarization measurements had traditionally been performed by analyzing the spin of recoil protons. The drawbacks of this technique are: (i) it involves double scattering, resulting in poor accuracy of the data, and (ii) a carbon analyzer can only be used for a limited region of energy.

  1. Infrared Spectroscopic Imaging of Latent Fingerprints and Associated Forensic Evidence

    PubMed Central

    Chen, Tsoching; Schultz, Zachary D.; Levin, Ira W.

    2011-01-01

    Fingerprints reflecting a specific chemical history, such as exposure to explosives, are clearly distinguished from overlapping, and interfering latent fingerprints using infrared spectroscopic imaging techniques and multivariate analysis. PMID:19684917

  2. Effect of Heat Treatment on the Structural Properties of TiO2 Films Produced by Sol-Gel Spin Coating Technique

    NASA Astrophysics Data System (ADS)

    Nebi, M.; Peker, D.

    2016-10-01

    Due to have superior properties as fotocatalyst and have wide band gap, TiO2 thin films often investigated by researchers and used by technological applications widely. In this study TiO2 films were deposited on glass substrate by Sol-Gel Spin Coating Technic. TiO2 films were deposited at different number of layer and then annealed at 400o C, 500o C, and 600o C in air. Effect of anneal temperature to structural properties were investigated by XRD analysis. It was observed by the light of XRD results that the structural properties of films had changed by anneal temperature.

  3. Spectroscopic and theoretical studies of the low-lying states of BaO{sup +}

    SciTech Connect

    Bartlett, Joshua H.; VanGundy, Robert A.; Heaven, Michael C.

    2015-07-28

    The BaO{sup +} cation is of interest from the perspectives of electronic structure and the potential for cooling to ultra-cold temperatures. Spectroscopic data for the ion have been obtained using a two-color photoionization technique. The ionization energy for BaO was found to be 6.8123(3) eV. The ground state of BaO{sup +} was identified as X{sup 2}Σ{sup +}, and both vibrational and rotational constants were determined. Vibrationally resolved spectra were recorded for A{sup 2}Π, the first electronically excited state. These data yielded the term energy, vibrational frequency, and the spin-orbit interaction constant. Relativistic electronic structure calculations were carried out using multi-reference configuration interaction (MRCI), coupled cluster and density functional theory methods. Transition moments for the pure vibrational and A{sup 2}Π-X{sup 2}Σ{sup +} transitions were predicted using the MRCI method.

  4. Multislice 1H magnetic resonance spectroscopic imaging: assessment of epilepsy, Alzheimer's disease, and amyotrophic lateral sclerosis

    NASA Astrophysics Data System (ADS)

    Weiner, Michael W.; Maudsley, Andrew A.; Schuff, Norbert; Soher, Brian J.; Vermathen, Peter P.; Fein, George; Laxer, Kenneth D.

    1998-07-01

    Proton magnetic resonance spectroscopic imaging (1H MRSI) with volume pre-selection (i.e. by PRESS) or multislice 1H MRSI was used to investigate changes in brain metabolites in Alzheimer's disease, epilepsy, and amyotrophic lateral sclerosis. Examples of results from several ongoing clinical studies are provided. Multislice 1H MRSI of the human brain, without volume pre-selection offers considerable advantages over previously available techniques. Furthermore, MRI tissue segmentation and completely automated spectra curve fitting greatly facilitate quantitative data analysis. Future efforts will be devoted to obtaining full brain coverage and data acquisition at short spin echo times (TE less than 30 ms) for the detection of metabolites with short T2 relaxation times.

  5. Effects of Concentration of Precursor and Annealing Temperature on the Optical Properties of Nanostructured Al- doped Zinc Oxide (AZO) Thin films Prepared by Sol-Gel Spin Coating Technique

    NASA Astrophysics Data System (ADS)

    Yusuf, Gbadebo; Awodugba, Ayodeji; Raimi, Adepoju; Efunwole, Hezekiah; Familusi, Timothy

    2013-03-01

    This work investigates the effects of concentration of precursor and annealing temperature on the optical properties of nanostructured Al-doped (AZO) zinc oxide thin films prepared by sol-gel spin coating technique. The sols were prepared using concentration of zinc acetate dehydrate which was varied between 0.1 and 1.4 mole/liter. Aluminium chloride was used as dopant while the annealing temperature of 400° to 650° was chosen. The results show that the concentration between 0.3 to 0.6 moles/liter zinc acetate dehydrate in solution resulted in good thin films with high preferential c-axis orientation and optical transmission reveal a good transmittance within the visible wavelength spectrum region while the concentrations that fall outside this range did not yield films with good c-axis orientation. The films deposited at annealing temperatures 500° and 650° showed surface structures much smaller than 400°. The Spin coating technique creates ZnO films with potential for application as transparent electrodes in optoelectronic devices such as solar cell. The Authors would like to Acknowledge the encouragement and financial support from the Management of Osun state Polytechnic, Iree.

  6. Electrically-induced Spin Coherence by Ultrafast Electrical Spin Injection.

    NASA Astrophysics Data System (ADS)

    Beschoten, B.; Schreiber, L.; Moritz, J.; Schwark, C.; Guentherodt, G.; Lou, X.; Crowell, P.; Adelmann, C.; Palmstrom, C.

    2008-03-01

    Efficient electrical spin injection from a ferromagnet into a semiconductor has been demonstrated for various material systems by steady-state experiments. We introduce a novel time-resolved technique based on electrical pumping and optical probing. As a pump we apply ultrafast current pulses (˜200ps) to electrically inject spin packets from an iron layer through a reverse biased Schottky barrier into a n-GaAs layer. Spin coherence in the semiconductor is probed by subsequent spin precession in a transverse magnetic field using time-resolved Faraday rotation. We observe spin precession for current pulse widths down to 200 ps. The spin polarization of the spin packets is directly measured by Faraday rotation and is found to increase linearly with the current pulse width for pulses shorter than 3 ns at small magnetic fields. This finding together with independent measurements of the samples' high frequency bandwidth indicate that even shorter than 200 ps pulses might be used for generating coherent spin currents in our devices. Work supported by BMBF, DFG and HGF.

  7. Induction-detection electron spin resonance with spin sensitivity of a few tens of spins

    SciTech Connect

    Artzi, Yaron; Twig, Ygal; Blank, Aharon

    2015-02-23

    Electron spin resonance (ESR) is a spectroscopic method that addresses electrons in paramagnetic materials directly through their spin properties. ESR has many applications, ranging from semiconductor characterization to structural biology and even quantum computing. Although it is very powerful and informative, ESR traditionally suffers from low sensitivity, requiring many millions of spins to get a measureable signal with commercial systems using the Faraday induction-detection principle. In view of this disadvantage, significant efforts were made recently to develop alternative detection schemes based, for example, on force, optical, or electrical detection of spins, all of which can reach single electron spin sensitivity. This sensitivity, however, comes at the price of limited applicability and usefulness with regard to real scientific and technological issues facing modern ESR which are currently dealt with conventional induction-detection ESR on a daily basis. Here, we present the most sensitive experimental induction-detection ESR setup and results ever recorded that can detect the signal from just a few tens of spins. They were achieved thanks to the development of an ultra-miniature micrometer-sized microwave resonator that was operated at ∼34 GHz at cryogenic temperatures in conjunction with a unique cryogenically cooled low noise amplifier. The test sample used was isotopically enriched phosphorus-doped silicon, which is of significant relevance to spin-based quantum computing. The sensitivity was experimentally verified with the aid of a unique high-resolution ESR imaging approach. These results represent a paradigm shift with respect to the capabilities and possible applications of induction-detection-based ESR spectroscopy and imaging.

  8. Induction-detection electron spin resonance with spin sensitivity of a few tens of spins

    NASA Astrophysics Data System (ADS)

    Artzi, Yaron; Twig, Ygal; Blank, Aharon

    2015-02-01

    Electron spin resonance (ESR) is a spectroscopic method that addresses electrons in paramagnetic materials directly through their spin properties. ESR has many applications, ranging from semiconductor characterization to structural biology and even quantum computing. Although it is very powerful and informative, ESR traditionally suffers from low sensitivity, requiring many millions of spins to get a measureable signal with commercial systems using the Faraday induction-detection principle. In view of this disadvantage, significant efforts were made recently to develop alternative detection schemes based, for example, on force, optical, or electrical detection of spins, all of which can reach single electron spin sensitivity. This sensitivity, however, comes at the price of limited applicability and usefulness with regard to real scientific and technological issues facing modern ESR which are currently dealt with conventional induction-detection ESR on a daily basis. Here, we present the most sensitive experimental induction-detection ESR setup and results ever recorded that can detect the signal from just a few tens of spins. They were achieved thanks to the development of an ultra-miniature micrometer-sized microwave resonator that was operated at ˜34 GHz at cryogenic temperatures in conjunction with a unique cryogenically cooled low noise amplifier. The test sample used was isotopically enriched phosphorus-doped silicon, which is of significant relevance to spin-based quantum computing. The sensitivity was experimentally verified with the aid of a unique high-resolution ESR imaging approach. These results represent a paradigm shift with respect to the capabilities and possible applications of induction-detection-based ESR spectroscopy and imaging.

  9. Quantitative spin polarization analysis in photoelectron emission microscopy with an imaging spin filter.

    PubMed

    Tusche, Christian; Ellguth, Martin; Krasyuk, Alexander; Winkelmann, Aimo; Kutnyakhov, Dmytro; Lushchyk, Pavel; Medjanik, Katerina; Schönhense, Gerd; Kirschner, Jürgen

    2013-07-01

    Using a photoelectron emission microscope (PEEM), we demonstrate spin-resolved electron spectroscopic imaging of ultrathin magnetic Co films grown on Cu(100). The spin-filter, based on the spin-dependent reflection of low energy electrons from a W(100) crystal, is attached to an aberration corrected electrostatic energy analyzer coupled to an electrostatic PEEM column. We present a method for the quantitative measurement of the electron spin polarization at 4 × 10³ points of the PEEM image, simultaneously. This approach uses the subsequent acquisition of two images with different scattering energies of the electrons at the W(100) target to directly derive the spin polarization without the need of magnetization reversal of the sample.

  10. Cavity cooling of an ensemble spin system.

    PubMed

    Wood, Christopher J; Borneman, Troy W; Cory, David G

    2014-02-07

    We describe how sideband cooling techniques may be applied to large spin ensembles in magnetic resonance. Using the Tavis-Cummings model in the presence of a Rabi drive, we solve a Markovian master equation describing the joint spin-cavity dynamics to derive cooling rates as a function of ensemble size. Our calculations indicate that the coupled angular momentum subspaces of a spin ensemble containing roughly 10(11) electron spins may be polarized in a time many orders of magnitude shorter than the typical thermal relaxation time. The described techniques should permit efficient removal of entropy for spin-based quantum information processors and fast polarization of spin samples. The proposed application of a standard technique in quantum optics to magnetic resonance also serves to reinforce the connection between the two fields, which has recently begun to be explored in further detail due to the development of hybrid designs for manufacturing noise-resilient quantum devices.

  11. Spin ejector

    DOEpatents

    Andersen, John A.; Flanigan, John J.; Kindley, Robert J.

    1978-01-01

    The disclosure relates to an apparatus for spin ejecting a body having a flat plate base containing bosses. The apparatus has a base plate and a main ejection shaft extending perpendicularly from the base plate. A compressible cylindrical spring is disposed about the shaft. Bearings are located between the shaft and the spring. A housing containing a helical aperture releasably engages the base plate and surrounds the shaft bearings and the spring. A piston having an aperture follower disposed in the housing aperture is seated on the spring and is guided by the shaft and the aperture. The spring is compressed and when released causes the piston to spin eject the body.

  12. Recovery of spinning satellites

    NASA Technical Reports Server (NTRS)

    Coppey, J. M.; Mahaffey, W. R.

    1977-01-01

    The behavior of a space tug and a spinning satellite in a coupled configuration was simulated and analyzed. A docking concept was developed to investigate the requirements pertaining to the design of a docking interface. Sensing techniques and control requirements for the chase vehicle were studied to assess the feasibility of an automatic docking. The effects of nutation dampers and liquid propellant slosh motion upon the docking transient were investigated.

  13. Spinning yarns for years

    NASA Astrophysics Data System (ADS)

    Kowalewski, Grzegorz

    1997-05-01

    Applications of rather routine high speed photography techniques for research of some textile technologies invented, developed, improved or investigated by the Technical University of Lodz are presented. The following technologies and processes are mentioned: sewing, knitting, spinning, texturing, weaving (including pneumatic methods employed in some technologies). Rotating prism cameras, microsecond flash guns, stereo photography have been mainly applied. Most HSP applications and examples are illustrated by a video presentation.

  14. Muon spin rotation in solids

    NASA Technical Reports Server (NTRS)

    Stronach, C. E.

    1983-01-01

    The muon spin rotation (MuSR) technique is used to probe the microscopic electron density in materials. High temperature MuSR and magnetization measurements in nickel are in progress to allow an unambiguous determination of the muon impurity interaction and the impurity induced change in local spin density. The first results on uniaxial stress induced frequency shifts in an Fe single crystal are also reported.

  15. Spin polarized tunneling study on spin hall metals and topological insulators (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Liu, Luqiao

    2016-10-01

    Spin orbit interactions give rise to interesting physics phenomena in solid state materials such as the spin Hall effect (SHE) and topological insulator surface states. Those effects have been extensively studied using various electrical detection methods. However, to date most experiments focus only on characterizing electrons near the Fermi surface, while spin-orbit interaction is expected to be energy dependent. Here we developed a tunneling spectroscopy technique to measure spin Hall materials and topological insulators under finite bias voltages. By electrically injecting spin polarized electrons into spin Hall metals or topological insulators using tunnel junctions and measuring the induced transverse voltage, we are able to study SHE in typical 5d transition metals and the spin momentum locking in topological insulators. For spin Hall effect metals, the magnitude of the spin Hall angle has been a highly controversial topic in previous studies. Results obtained from various techniques can differ by more than an order of magnitude. Our results from this transport measurement turned out to be consistent with the values obtained from spin Hall torque measurements, which can help to address the long debating issue. Besides the magnitude, the voltage dependent spectra from our experiment also provide useful information in distinguishing between different potential mechanisms. Finally, because of the impedance matching capability of tunnel junctions, the spin polarized tunneling technique can also be used as a powerful tool to measure resistive materials such as the topological insulators. Orders of magnitude improvement in the effective spin Hall angle was demonstrated through our measurement

  16. High-spin states and shell structure of the odd-odd nucleus {sup 90}Nb

    SciTech Connect

    Cui, X.Z.; Zhang, Z.L.; Meng, R.; Yang, C.X.; Zhu, L.H.; Wu, X.G.; Wang, Z.M.; He, C.Y.; Li, G.S.; Wen, S.X.; Ma, R.G.; Liu, Y.; Luo, P.; Zheng, Y.; Ndontchueng, M.M.; Huo, J.D.

    2005-10-01

    The high-spin states of the odd-odd nucleus {sup 90}Nb have been investigated with in-beam {gamma}-spectroscopic techniques via the {sup 76}Ge({sup 19}F,5n){sup 90}Nb reaction at a beam energy of 80 MeV. {gamma}-{gamma} coincidences were measured using a {gamma}-ray detector array. Twenty new {gamma} rays have been assigned to {sup 90}Nb and the level scheme has been extended up to an excitation energy of 8.095 MeV at spin 18({Dirac_h}/2{pi}). The level structure of {sup 90}Nb at high spin states has been well reproduced using semiempirical shell-model calculations in the model space {pi}(1p{sub 1/2},0f{sub 5/2},0g{sub 9/2}){nu}(0g{sub 9/2}). The results show that the excitation of protons plays an important role in generating the high-spin states of {sup 90}Nb.

  17. Identification of pH-sensitive regions in the mouse prion by the cysteine-scanning spin-labeling ESR technique

    SciTech Connect

    Watanabe, Yasuko; Inanami, Osamu . E-mail: inanami@vetmed.hokudai.ac.jp; Horiuchi, Motohiro; Hiraoka, Wakako; Shimoyama, Yuhei; Inagaki, Fuyuhiko; Kuwabara, Mikinori

    2006-11-24

    We analyzed the pH-induced mobility changes in moPrP{sup C} {alpha}-helix and {beta}-sheets by cysteine-scanning site-directed spin labeling (SDSL) with ESR. Nine amino acid residues of {alpha}-helix1 (H1, codon 143-151), four amino acid residues of {beta}-sheet1 (S1, codon 127-130), and four amino acid residues of {beta}-sheet2 (S2, codon 160-163) were substituted for by cysteine residues. These recombinant mouse PrP{sup C} (moPrP{sup C}) mutants were reacted with a methane thiosulfonate sulfhydryl-specific spin labeling reagent (MTSSL). The 1/{delta}H of the central ({sup 14}N hyperfine) component (M{sub I} = 0) in the ESR spectrum of spin-labeled moPrP{sup C} was measured as a mobility parameter of nitroxide residues (R1). The mobilities of E145R1 and Y149R1 at pH 7.4, which was identified as a tertiary contact site by a previous NMR study of moPrP, were lower than those of D143R1, R147R1, and R150R1 reported on the helix surface. Thus, the mobility in the H1 region in the neutral solution was observed with the periodicity associated with a helical structure. On the other hand, the values in the S2 region, known to be located in the buried side, were lower than those in the S1 region located in the surface side. These results indicated that the mobility parameter of the nitroxide label was well correlated with the 3D structure of moPrP. Furthermore, the present study clearly demonstrated three pH-sensitive sites in moPrP, i.e. (1) the N-terminal tertiary contact site of H1 (2) the C-terminal end of H1, and (3) the S2 region. In particular, among these pH-sensitive sites, the N-terminal tertiary contact region of H1 was found to be the most pH-sensitive one and was easily converted to a flexible structure by a slight decrease of pH in the solution. These data provided molecular evidence to explain the cellular mechanism for conversion from PrP{sup C} to PrP{sup Sc} in acidic organelles such as the endosome.

  18. Kitaev exchange and field-induced quantum spin-liquid states in honeycomb α-RuCl3.

    PubMed

    Yadav, Ravi; Bogdanov, Nikolay A; Katukuri, Vamshi M; Nishimoto, Satoshi; van den Brink, Jeroen; Hozoi, Liviu

    2016-11-30

    Large anisotropic exchange in 5d and 4d oxides and halides open the door to new types of magnetic ground states and excitations, inconceivable a decade ago. A prominent case is the Kitaev spin liquid, host of remarkable properties such as protection of quantum information and the emergence of Majorana fermions. Here we discuss the promise for spin-liquid behavior in the 4d(5) honeycomb halide α-RuCl3. From advanced electronic-structure calculations, we find that the Kitaev interaction is ferromagnetic, as in 5d(5) iridium honeycomb oxides, and indeed defines the largest superexchange energy scale. A ferromagnetic Kitaev coupling is also supported by a detailed analysis of the field-dependent magnetization. Using exact diagonalization and density-matrix renormalization group techniques for extended Kitaev-Heisenberg spin Hamiltonians, we find indications for a transition from zigzag order to a gapped spin liquid when applying magnetic field. Our results offer a unified picture on recent magnetic and spectroscopic measurements on this material and open new perspectives on the prospect of realizing quantum spin liquids in d(5) halides and oxides in general.

  19. Kitaev exchange and field-induced quantum spin-liquid states in honeycomb α-RuCl3

    NASA Astrophysics Data System (ADS)

    Yadav, Ravi; Bogdanov, Nikolay A.; Katukuri, Vamshi M.; Nishimoto, Satoshi; van den Brink, Jeroen; Hozoi, Liviu

    2016-11-01

    Large anisotropic exchange in 5d and 4d oxides and halides open the door to new types of magnetic ground states and excitations, inconceivable a decade ago. A prominent case is the Kitaev spin liquid, host of remarkable properties such as protection of quantum information and the emergence of Majorana fermions. Here we discuss the promise for spin-liquid behavior in the 4d5 honeycomb halide α-RuCl3. From advanced electronic-structure calculations, we find that the Kitaev interaction is ferromagnetic, as in 5d5 iridium honeycomb oxides, and indeed defines the largest superexchange energy scale. A ferromagnetic Kitaev coupling is also supported by a detailed analysis of the field-dependent magnetization. Using exact diagonalization and density-matrix renormalization group techniques for extended Kitaev-Heisenberg spin Hamiltonians, we find indications for a transition from zigzag order to a gapped spin liquid when applying magnetic field. Our results offer a unified picture on recent magnetic and spectroscopic measurements on this material and open new perspectives on the prospect of realizing quantum spin liquids in d5 halides and oxides in general.

  20. Kitaev exchange and field-induced quantum spin-liquid states in honeycomb α-RuCl3

    PubMed Central

    Yadav, Ravi; Bogdanov, Nikolay A.; Katukuri, Vamshi M.; Nishimoto, Satoshi; van den Brink, Jeroen; Hozoi, Liviu

    2016-01-01

    Large anisotropic exchange in 5d and 4d oxides and halides open the door to new types of magnetic ground states and excitations, inconceivable a decade ago. A prominent case is the Kitaev spin liquid, host of remarkable properties such as protection of quantum information and the emergence of Majorana fermions. Here we discuss the promise for spin-liquid behavior in the 4d5 honeycomb halide α-RuCl3. From advanced electronic-structure calculations, we find that the Kitaev interaction is ferromagnetic, as in 5d5 iridium honeycomb oxides, and indeed defines the largest superexchange energy scale. A ferromagnetic Kitaev coupling is also supported by a detailed analysis of the field-dependent magnetization. Using exact diagonalization and density-matrix renormalization group techniques for extended Kitaev-Heisenberg spin Hamiltonians, we find indications for a transition from zigzag order to a gapped spin liquid when applying magnetic field. Our results offer a unified picture on recent magnetic and spectroscopic measurements on this material and open new perspectives on the prospect of realizing quantum spin liquids in d5 halides and oxides in general. PMID:27901091

  1. Y{sub 3}Fe{sub 5}O{sub 12} spin pumping for quantitative understanding of pure spin transport and spin Hall effect in a broad range of materials (invited)

    SciTech Connect

    Du, Chunhui; Wang, Hailong; Hammel, P. Chris; Yang, Fengyuan

    2015-05-07

    Using Y{sub 3}Fe{sub 5}O{sub 12} (YIG) thin films grown by our sputtering technique, we study dynamic spin transport in nonmagnetic, ferromagnetic, and antiferromagnetic (AF) materials by ferromagnetic resonance spin pumping. From both inverse spin Hall effect and damping enhancement, we determine the spin mixing conductance and spin Hall angle in many metals. Surprisingly, we observe robust spin conduction in AF insulators excited by an adjacent YIG at resonance. This demonstrates that YIG spin pumping is a powerful and versatile tool for understanding spin Hall physics, spin-orbit coupling, and magnetization dynamics in a broad range of materials.

  2. Observation of the spin Seebeck effect.

    PubMed

    Uchida, K; Takahashi, S; Harii, K; Ieda, J; Koshibae, W; Ando, K; Maekawa, S; Saitoh, E

    2008-10-09

    The generation of electric voltage by placing a conductor in a temperature gradient is called the Seebeck effect. Its efficiency is represented by the Seebeck coefficient, S, which is defined as the ratio of the generated electric voltage to the temperature difference, and is determined by the scattering rate and the density of the conduction electrons. The effect can be exploited, for example, in thermal electric-power generators and for temperature sensing, by connecting two conductors with different Seebeck coefficients, a device called a thermocouple. Here we report the observation of the thermal generation of driving power, or voltage, for electron spin: the spin Seebeck effect. Using a recently developed spin-detection technique that involves the spin Hall effect, we measure the spin voltage generated from a temperature gradient in a metallic magnet. This thermally induced spin voltage persists even at distances far from the sample ends, and spins can be extracted from every position on the magnet simply by attaching a metal. The spin Seebeck effect observed here is directly applicable to the production of spin-voltage generators, which are crucial for driving spintronic devices. The spin Seebeck effect allows us to pass a pure spin current, a flow of electron spins without electric currents, over a long distance. These innovative capabilities will invigorate spintronics research.

  3. Charge-to-Spin Conversion and Spin Diffusion in Bi/Ag Bilayers Observed by Spin-Polarized Positron Beam

    NASA Astrophysics Data System (ADS)

    Zhang, H. J.; Yamamoto, S.; Gu, B.; Li, H.; Maekawa, M.; Fukaya, Y.; Kawasuso, A.

    2015-04-01

    Charge-to-spin conversion induced by the Rashba-Edelstein effect was directly observed for the first time in samples with no magnetic layer. A spin-polarized positron beam was used to probe the spin polarization of the outermost surface electrons of Bi /Ag /Al2O3 and Ag /Bi /Al2O3 when charge currents were only associated with the Ag layers. An opposite surface spin polarization was found between Bi /Ag /Al2O3 and Ag /Bi /Al2O3 samples with the application of a charge current in the same direction. The surface spin polarizations of both systems decreased exponentially with the outermost layer thickness, suggesting the occurrence of spin diffusion from the Bi/Ag interface to the outermost surfaces. This work provides a new technique to measure spin diffusion length.

  4. Spin pumping and spin Seebeck effect

    NASA Astrophysics Data System (ADS)

    Saitoh, Eiji

    2012-02-01

    Utilization of a spin current, a flow of electrons' spins in a solid, is the key technology in spintronics that will allow the achievement of efficient magnetic memories and computing devices. In this technology, generation and detection of spin currents are necessary. Here, we review inverse spin-Hall effect and spin-current-generation phenomena recently discovered both in metals and insulators: inverse spin-Hall effect, spin pumping, and spin Seebeck effect. (1)Spin pumping and spin torque in a Mott insulator system We found that spin pumping and spin torque effects appear also at an interface between Pt and an insulator YIG.. This means that we can connect a spin current carried by conduction electrons and a spin-wave spin current flowing in insulators. We demonstrate electric signal transmission by using these effects and interconversion of the spin currents [1]. (2) Spin Seebeck effect We have observed, by using the inverse spin-Hall effect [2], spin voltage generation from a heat current in a NiFe, named the spin-Seebeck effect [3]. Surprisingly, spin-Seebeck effect was found to appear even in insulators [4], a situation completely different from conventional charge Seebeck effect. The result implies an important role of elementary excitation in solids beside charge in the spin Seebeck effect. In the talk, we review the recent progress of the research on this effect. This research is collaboration with K. Ando, K. Uchida, Y. Kajiwara, S. Maekawa, G. E. W. Bauer, S. Takahashi, and J. Ieda. [4pt] [1] Y. Kajiwara and E. Saitoh et al. Nature 464 (2010) 262. [0pt] [2] E. Saitoh et al., Appl. Phys. Lett. 88 (2006) 182509. [0pt] [3] K. Uchida and E. Saitoh et al., Nature 455 (2008)778. [0pt] [4] K. Uchida and E. Saitoh et al.,Nature materials 9 (2010) 894 - 897.

  5. Thermal imaging of spin Peltier effect.

    PubMed

    Daimon, Shunsuke; Iguchi, Ryo; Hioki, Tomosato; Saitoh, Eiji; Uchida, Ken-Ichi

    2016-12-12

    The Peltier effect modulates the temperature of a junction comprising two different conductors in response to charge currents across the junction, which is used in solid-state heat pumps and temperature controllers in electronics. Recently, in spintronics, a spin counterpart of the Peltier effect was observed. The 'spin Peltier effect' modulates the temperature of a magnetic junction in response to spin currents. Here we report thermal imaging of the spin Peltier effect; using active thermography technique, we visualize the temperature modulation induced by spin currents injected into a magnetic insulator from an adjacent metal. The thermal images reveal characteristic distribution of spin-current-induced heat sources, resulting in the temperature change confined only in the vicinity of the metal/insulator interface. This finding allows us to estimate the actual magnitude of the temperature modulation induced by the spin Peltier effect, which is more than one order of magnitude greater than previously believed.

  6. Thermal imaging of spin Peltier effect

    PubMed Central

    Daimon, Shunsuke; Iguchi, Ryo; Hioki, Tomosato; Saitoh, Eiji; Uchida, Ken-ichi

    2016-01-01

    The Peltier effect modulates the temperature of a junction comprising two different conductors in response to charge currents across the junction, which is used in solid-state heat pumps and temperature controllers in electronics. Recently, in spintronics, a spin counterpart of the Peltier effect was observed. The ‘spin Peltier effect' modulates the temperature of a magnetic junction in response to spin currents. Here we report thermal imaging of the spin Peltier effect; using active thermography technique, we visualize the temperature modulation induced by spin currents injected into a magnetic insulator from an adjacent metal. The thermal images reveal characteristic distribution of spin-current-induced heat sources, resulting in the temperature change confined only in the vicinity of the metal/insulator interface. This finding allows us to estimate the actual magnitude of the temperature modulation induced by the spin Peltier effect, which is more than one order of magnitude greater than previously believed. PMID:27941953

  7. Thermal imaging of spin Peltier effect

    NASA Astrophysics Data System (ADS)

    Daimon, Shunsuke; Iguchi, Ryo; Hioki, Tomosato; Saitoh, Eiji; Uchida, Ken-Ichi

    2016-12-01

    The Peltier effect modulates the temperature of a junction comprising two different conductors in response to charge currents across the junction, which is used in solid-state heat pumps and temperature controllers in electronics. Recently, in spintronics, a spin counterpart of the Peltier effect was observed. The `spin Peltier effect' modulates the temperature of a magnetic junction in response to spin currents. Here we report thermal imaging of the spin Peltier effect; using active thermography technique, we visualize the temperature modulation induced by spin currents injected into a magnetic insulator from an adjacent metal. The thermal images reveal characteristic distribution of spin-current-induced heat sources, resulting in the temperature change confined only in the vicinity of the metal/insulator interface. This finding allows us to estimate the actual magnitude of the temperature modulation induced by the spin Peltier effect, which is more than one order of magnitude greater than previously believed.

  8. Measurement of spin coherence using Raman scattering

    NASA Astrophysics Data System (ADS)

    Sun, Z.; Delteil, A.; Faelt, S.; Imamoǧlu, A.

    2016-06-01

    Ramsey interferometry provides a natural way to determine the coherence time of most qubit systems. Recent experiments on quantum dots, however, demonstrated that dynamical nuclear spin polarization can strongly influence the measurement process, making it difficult to extract the T2* coherence time using standard optical Ramsey pulses. Here, we demonstrate an alternative method for spin coherence measurement that is based on first-order coherence of photons generated in spin-flip Raman scattering. We show that if a quantum emitter is driven by a weak monochromatic laser, Raman coherence is determined exclusively by spin coherence, allowing for a direct determination of spin T2* time. When combined with coherence measurements on Rayleigh scattered photons, our technique enables us to identify coherent and incoherent contributions to resonance fluorescence, and to minimize the latter. We verify the validity of our technique by comparing our results to those determined from Ramsey interferometry for electron and heavy-hole spins.

  9. High spin γ -ray spectroscopy in 41Ca

    NASA Astrophysics Data System (ADS)

    Bhattacharjee, R.; Samanta, S.; Das, S.; Bhattacharjee, S. S.; Raut, R.; Ghugre, S. S.; Sinha, A. K.; Garg, U.; Chakrabarti, R.; Mukhopadhyay, S.; Dhal, A.; Singh, R. P.; Madhavan, N.; Muralithar, S.

    2016-11-01

    High spin states in 41Ca have been investigated by using γ -ray spectroscopic techniques following the 27Al(16O,p n )41Ca fusion-evaporation reaction. Around twelve new transitions belonging to 41Ca have been observed and placed in the level scheme, which now has been extended up to Ex˜9 MeV. The spin-parity assignments for the observed levels were arrived at following the analysis of both the coincidence intensity anisotropies and linear polarization measurements. The established 5p-4h band was extended up to Jπ=19 /2- . The observations of Doppler shape and shifts facilitated the estimation of the level lifetimes by using the Doppler shift attenuation method. The lifetimes were validated with respect to previous measurements and lifetime of a few levels has been arrived at for the first time. Shell-model calculations were carried out to explain the observed level structure of the nucleus and are indicative of both single-particle and collective degrees of freedom in this N ˜Z ˜20 nucleus.

  10. NV magnetic imaging of topological spin patterns in magnetic multilayers

    NASA Astrophysics Data System (ADS)

    Casola, Francesco; Dovzhenko, Yuliya; Zhou, Xu; Warner, Marc; Schlotter, Sarah; Beach, Geoffrey; Walsworth, Ronald; Yacoby, Amir

    2015-05-01

    Scanning diamond microscopes with an atom-like nitrogen-vacancy (NV) color center near the probe tip have recently emerged as a leading tool for the study of nanoscale magnetism in a broad range of systems. We report on the development of a new approach for positiong a single NV centre at a few nanometres from the sample of interest. This is achieved by fabricating our magnetic device at the top of a polished quartz fiber, whose distance from a diamond nanopillar containing NV centers is then controlled via an atomic force microscope feedback. We employ this method for the investigation of thin ferromagnetic Co/Pt multilayers, where interfacial spin-orbit coupling is expected to stabilize complex topologically protected spin textures. The few-nanometers real-space extension of an isolated skyrmion structure in thin magnetic films makes its detection via standard spectroscopic techniques challenging, suggesting how NV magnetometry can be a unique candidate for the study of novel mesoscopic magnetism.

  11. The optical characterization of organometallic complex thin films by spectroscopic ellipsometry and photovoltaic diode application

    SciTech Connect

    Özaydın, C.; Güllü, Ö.; Pakma, O.; Ilhan, S.; Akkılıç, K.

    2016-05-15

    Highlights: • Optical properties and thickness of the A novel organometallic complex (OMC) film were investigated by spectroscopic ellipsometry (SE). • Au/OMC/n-Si metal/interlayer/semiconductor (MIS) diode has been fabricated • This paper presents the I–V analysis of Au/OMC/n-Si MIS diode. • Current–voltage and photovoltaic properties of the diode were investigated. - Abstract: In this work, organometallic complex (OMC) films have been deposited onto glass or silicon substrates by spin coating technique and their photovoltaic application potential has been investigated. Optical properties and thickness of the film have been investigated by spectroscopic ellipsometry (SE). Also, transmittance spectrum has been taken by UV/vis spectrophotometer. The optical method has been used to determine the band gap value of the films. Also, Au/OMC/n-Si metal/interlayer/semiconductor (MIS) diode has been fabricated. Current–voltage and photovoltaic properties of the structure were investigated. The ideality factor (n) and barrier height (Φ{sub b}) values of the diode were found to be 2.89 and 0.79 eV, respectively. The device shows photovoltaic behavior with a maximum open-circuit voltage of 396 mV and a short circuit current of 33.8 μA under 300 W light.

  12. Magnetism and lithium diffusion in Li xCoO 2 by a muon-spin rotation and relaxation (μ +SR) technique

    NASA Astrophysics Data System (ADS)

    Mukai, Kazuhiko; Sugiyama, Jun; Ikedo, Yutaka; Nozaki, Hiroshi; Shimomura, Koichiro; Nishiyama, Kusuo; Ariyoshi, Kingo; Ohzuku, Tsutomu

    Microscopic magnetism of the electrochemically Li-deintercaleted Li xCoO 2 powders has been investigated by muon-spin rotation and relaxation (μ +SR) spectroscopy in the temperature (T) range between 10 and 300 K. Weak transverse-field μ +SR measurements indicate that localized moments appear in LiCoO 2 below 60 K, while both Li 0.53CoO 2 and Li 0.04CoO 2 are paramagnetic even at 10 K. Zero-field μ +SR measurements for the samples with x = 0.53 and 0.04 show that the field distribution width (Δ) due to randomly oriented nuclear magnetic moments of 7Li and 59Co decreases monotonically with increasing T up to 250 K, and then it decreases steeper (increasing slope (d Δ/d T)) above 250 K. Because the muon hopping rate (ν) is almost T independent for Li 0.53CoO 2 below 300 K, the decrease in Δ suggests that the time scale of Li + diffusion in Li xCoO 2 is within a microsecond scale.

  13. Spin Electronics

    DTIC Science & Technology

    2003-08-01

    spectroscopy laboratory including high pulse power capabilities (regenerative amplifiers and optical parametric amplifiers ) and broad spectral range ...The data identify narrow ranges of doping concentrations where spin lifetimes in semiconductors are enhanced by orders of magnitude, culminating in... dynamic measurements in the 10 to 100 picoseconds (ps) range . • A second program, which will come to fruition within one to two years, has the name

  14. Spectroscopic Studies of Abell Clusters

    NASA Astrophysics Data System (ADS)

    Way, Michael Joseph

    The objectives of this work are to use spectroscopic techniques to accurately categorize galaxies as either HII region star forming galaxies or as Active Galactic Nuclei powered via a black hole, and to use radial velocities and projected positions of galaxies in clusters to obtain the total cluster mass and its distribution. The masses and distributions compare well to X-ray mass measurements. The commonly used Dressler, A., Thompson, I. & Shectman, S. 1985, ApJ, 288, 481 technique for discriminating between Active Galactic Nuclei and HII region galaxies uses the measurement of the equivalent width of the emission lines (OII) 3727 A, H/beta, and (OIII) 5007 A. High quality spectra from 42 galaxies were taken and it is shown that their method is not capable of distinguishing between Active Galactic Nuclei and HII region galaxies. The emission line flux from H/beta, (OIII) 5007 A, (OI) 6300 A, Hα, (NII) 6583 A, and (SII) 6716+6731 A in combination with the method of Veilleux, S. & Osterbrock, D. E. 1987, ApJS, 63, 295 must be used to accurately distinguish between Active Galactic Nuclei and HII region galaxies. Galaxy radial velocities from spectroscopic data and their projected 2-D positions in clusters are used to obtain robust estimates of the total mass and mass distribution in two clusters. The total mass is calculated using the Virial theorem after removing substructure. The mass distribution is estimated via several robust statistical tests for 1-D, 2-D and 3-D structure. It is shown that the derived mass estimates agree well with those found independently from hot X-ray gas emission in clusters.

  15. spin pumping occurred under nonlinear spin precession

    NASA Astrophysics Data System (ADS)

    Zhou, Hengan; Fan, Xiaolong; Ma, Li; Zhou, Shiming; Xue, Desheng

    Spin pumping occurs when a pure-spin current is injected into a normal metal thin layer by an adjacent ferromagnetic metal layer undergoing ferromagnetic resonance, which can be understood as the inverse effect of spin torque, and gives access to the physics of magnetization dynamics and damping. An interesting question is that whether spin pumping occurring under nonlinear spin dynamics would differ from linear case. It is known that nonlinear spin dynamics differ distinctly from linear response, a variety of amplitude dependent nonlinear effect would present. It has been found that for spin precession angle above a few degrees, nonlinear damping term would present and dominated the dynamic energy/spin-moment dissipation. Since spin pumping are closely related to the damping process, it is interesting to ask whether the nonlinear damping term could be involved in spin pumping process. We studied the spin pumping effect occurring under nonlinear spin precession. A device which is a Pt/YIG microstrip coupled with coplanar waveguide was used. High power excitation resulted in spin precession entering in a nonlinear regime. Foldover resonance lineshape and nonlinear damping have been observed. Based on those nonlinear effects, we determined the values of the precession cone angles, and the maximum cone angle can reach a values as high as 21.5 degrees. We found that even in nonlinear regime, spin pumping is still linear, which means the nonlinear damping and foldover would not affect spin pumping process.

  16. Drift transport of helical spin coherence with tailored spin–orbit interactions

    PubMed Central

    Kunihashi, Y.; Sanada, H.; Gotoh, H.; Onomitsu, K.; Kohda, M.; Nitta, J.; Sogawa, T.

    2016-01-01

    Most future information processing techniques using electron spins in non-magnetic semiconductors will require both the manipulation and transfer of spins without their coherence being lost. The spin–orbit effective magnetic field induced by drifting electrons enables us to rotate the electron spins in the absence of an external magnetic field. However, the fluctuations in the effective magnetic field originating from the random scattering of electrons also cause undesirable spin decoherence, which limits the length scale of the spin transport. Here we demonstrate the drift transport of electron spins adjusted to a robust spin structure, namely a persistent spin helix. We find that the persistent spin helix enhances the spatial coherence of drifting spins, resulting in maximized spin decay length near the persistent spin helix condition. Within the enhanced distance of the spin transport, the transport path of electron spins can be modulated by employing time-varying in-plane voltages. PMID:26952129

  17. Spin decoherence of magnetic atoms on surfaces

    NASA Astrophysics Data System (ADS)

    Delgado, F.; Fernández-Rossier, J.

    2017-02-01

    We review the problem of spin decoherence of magnetic atoms deposited on a surface. Recent breakthroughs in scanning tunnelling microscopy (STM) make it possible to probe the spin dynamics of individual atoms, either isolated or integrated in nanoengineered spin structures. Transport pump and probe techniques with spin polarized tips permit measuring the spin relaxation time T1 , while novel demonstration of electrically driven STM single spin resonance has provided a direct measurement of the spin coherence time T2 of an individual magnetic adatom. Here we address the problem of spin decoherence from the theoretical point of view. First we provide a short general overview of decoherence in open quantum systems and we discuss with some detail ambiguities that arise in the case of degenerate spectra, relevant for magnetic atoms. Second, we address the physical mechanisms that allows probing the spin coherence of magnetic atoms on surfaces. Third, we discuss the main spin decoherence mechanisms at work on a surface, most notably, Kondo interaction, but also spin-phonon coupling and dephasing by Johnson noise. Finally, we briefly discuss the implications in the broader context of quantum technologies.

  18. Robust conversion of singlet spin order in coupled spin-1/2 pairs by adiabatically ramped RF-fields.

    PubMed

    Pravdivtsev, Andrey N; Kiryutin, Alexey S; Yurkovskaya, Alexandra V; Vieth, Hans-Martin; Ivanov, Konstantin L

    2016-12-01

    We propose a robust and highly efficient NMR technique to create singlet spin order from longitudinal spin magnetization in coupled spin-½ pairs and to perform backward conversion (singlet order)→magnetization. In this method we exploit adiabatic ramping of an RF-field in order to drive transitions between the singlet state and the T± triplet states of a spin pair under study. We demonstrate that the method works perfectly for both strongly and weakly coupled spin pairs, providing a conversion efficiency between the singlet spin order and magnetization, which is equal to the theoretical maximum. We anticipate that the proposed technique is useful for generating long-lived singlet order, for preserving spin hyperpolarization and for analyzing singlet spin order in nearly equivalent spin pairs in specially designed molecules and in low-field NMR studies.

  19. Data analysis techniques, differential cross sections, and spin density matrix elements for the reaction γp →ϕp

    NASA Astrophysics Data System (ADS)

    Dey, B.; Meyer, C. A.; Bellis, M.; Williams, M.; Adhikari, K. P.; Adikaram, D.; Aghasyan, M.; Amaryan, M. J.; Anderson, M. D.; Anefalos Pereira, S.; Ball, J.; Baltzell, N. A.; Battaglieri, M.; Bedlinskiy, I.; Biselli, A. S.; Bono, J.; Boiarinov, S.; Briscoe, W. J.; Brooks, W. K.; Burkert, V. D.; Carman, D. S.; Celentano, A.; Chandavar, S.; Colaneri, L.; Cole, P. L.; Contalbrigo, M.; Cortes, O.; Crede, V.; D'Angelo, A.; Dashyan, N.; De Vita, R.; De Sanctis, E.; Deur, A.; Djalali, C.; Doughty, D.; Dugger, M.; Dupre, R.; El Alaoui, A.; El Fassi, L.; Elouadrhiri, L.; Fedotov, G.; Fegan, S.; Fleming, J. A.; Garçon, M.; Gevorgyan, N.; Ghandilyan, Y.; Gilfoyle, G. P.; Giovanetti, K. L.; Girod, F. X.; Glazier, D. I.; Goetz, J. T.; Gothe, R. W.; Griffioen, K. A.; Guidal, M.; Hafidi, K.; Hanretty, C.; Harrison, N.; Hattawy, M.; Hicks, K.; Ho, D.; Holtrop, M.; Hyde, C. E.; Ilieva, Y.; Ireland, D. G.; Ishkhanov, B. S.; Jenkins, D.; Jo, H. S.; Joo, K.; Keller, D.; Khandaker, M.; Kim, A.; Kim, W.; Klein, A.; Klein, F. J.; Koirala, S.; Kubarovsky, V.; Kuhn, S. E.; Kuleshov, S. V.; Lenisa, P.; Livingston, K.; Lu, H.; MacGregor, I. J. D.; Markov, N.; Mayer, M.; McCracken, M. E.; McKinnon, B.; Mineeva, T.; Mirazita, M.; Mokeev, V.; Montgomery, R. A.; Moriya, K.; Moutarde, H.; Munevar, E.; Munoz Camacho, C.; Nadel-Turonski, P.; Niccolai, S.; Niculescu, G.; Niculescu, I.; Osipenko, M.; Pappalardo, L. L.; Paremuzyan, R.; Park, K.; Pasyuk, E.; Peng, P.; Phillips, J. J.; Pisano, S.; Pogorelko, O.; Pozdniakov, S.; Price, J. W.; Procureur, S.; Protopopescu, D.; Puckett, A. J. R.; Rimal, D.; Ripani, M.; Ritchie, B. G.; Rizzo, A.; Rossi, P.; Roy, P.; Sabatié, F.; Saini, M. S.; Schott, D.; Schumacher, R. A.; Seder, E.; Senderovich, I.; Sharabian, Y. G.; Simonyan, A.; Smith, E. S.; Sober, D. I.; Sokhan, D.; Stepanyan, S. S.; Stoler, P.; Strakovsky, I. I.; Strauch, S.; Sytnik, V.; Taiuti, M.; Tang, W.; Tkachenko, S.; Ungaro, M.; Vernarsky, B.; Vlassov, A. V.; Voskanyan, H.; Voutier, E.; Walford, N. K.; Watts, D. P.; Zachariou, N.; Zana, L.; Zhang, J.; Zhao, Z. W.; Zonta, I.; CLAS Collaboration

    2014-05-01

    High-statistics measurements of differential cross sections and spin density matrix elements for the reaction γp →ϕp have been made using the CLAS detector at Jefferson Lab. We cover center-of-mass energies (√s ) from 1.97 to 2.84 GeV, with an extensive coverage in the ϕ production angle. The high statistics of the data sample made it necessary to carefully account for the interplay between the ϕ natural lineshape and effects of the detector resolution, that are found to be comparable in magnitude. We study both the charged- (ϕ →K+K-) and neutral- (ϕ →KS0KL0) KK ¯ decay modes of the ϕ. Further, for the charged mode, we differentiate between the cases where the final K- track is directly detected or its momentum reconstructed as the total missing momentum in the event. The two charged-mode topologies and the neutral-mode have different resolutions and are calibrated against each other. Extensive usage is made of kinematic fitting to improve the reconstructed ϕ mass resolution. Our final results are reported in 10- and mostly 30-MeV-wide √s bins for the charged- and the neutral-modes, respectively. Possible effects from K+Λ* channels with pKK ¯ final states are discussed. These present results constitute the most precise and extensive ϕ photoproduction measurements to date and in conjunction with the ω photoproduction results recently published by CLAS, will greatly improve our understanding of low energy vector meson photoproduction.

  20. Data analysis techniques, differential cross sections, and spin density matrix elements for the reaction γp → Φp

    DOE PAGES

    Dey, B.; Meyer, C. A.; Bellis, M.; ...

    2014-05-27

    High-statistics measurements of differential cross sections and spin density matrix elements for the reaction γ p → Φp have been made using the CLAS detector at Jefferson Lab. We cover center-of-mass energies (√s) from 1.97 to 2.84 GeV, with an extensive coverage in the Φ production angle. The high statistics of the data sample made it necessary to carefully account for the interplay between the Φ natural lineshape and effects of the detector resolution, that are found to be comparable in magnitude. We study both the charged- (Φ → K⁺K⁻) and neutral- (Φ → K0SK0L)more » $$K\\bar{K}$$ decay modes of the Φ. Further, for the charged mode, we differentiate between the cases where the final K⁻ track is directly detected or its momentum reconstructed as the total missing momentum in the event. The two charged-mode topologies and the neutral-mode have different resolutions and are calibrated against each other. Extensive usage is made of kinematic fitting to improve the reconstructed Φ mass resolution. Our final results are reported in 10- and mostly 30-MeV-wide √s bins for the charged- and the neutral-mode, respectively. Possible effects from K⁺Λ* channels with p$$K\\bar{K}$$ final-states are discussed. These present results constitute the most precise and extensive Φ photoproduction measurements to date and in conjunction with the ω photoproduction results recently published by CLAS, will greatly improve our understanding of low energy vector meson photoproduction.« less

  1. Data analysis techniques, differential cross sections, and spin density matrix elements for the reaction γp → Φp

    SciTech Connect

    Dey, B.; Meyer, C. A.; Bellis, M.; Williams, M.; Adhikari, K. P.; Adikaram, D.; Aghasyan, M.; Amaryan, M. J.; Anderson, M. D.; Anefalos Pereira, S.; Ball, J.; Baltzell, N. A.; Battaglieri, M.; Bedlinskiy, I.; Biselli, A. S.; Bono, J.; Boiarinov, S.; Briscoe, W. J.; Brooks, W. K.; Burkert, V. D.; Carman, D. S.; Celentano, A.; Chandavar, S.; Colaneri, L.; Cole, P. L.; Contalbrigo, M.; Cortes, O.; Crede, V.; D'Angelo, A.; Dashyan, N.; De Vita, R.; De Sanctis, E.; Deur, A.; Djalali, C.; Doughty, D.; Dugger, M.; Dupre, R.; El Alaoui, A.; El Fassi, L.; Elouadrhiri, L.; Fedotov, G.; Fegan, S.; Fleming, J. A.; Garçon, M.; Gevorgyan, N.; Ghandilyan, Y.; Gilfoyle, G. P.; Giovanetti, K. L.; Girod, F. X.; Glazier, D. I.; Goetz, J. T.; Gothe, R. W.; Griffioen, K. A.; Guidal, M.; Hafidi, K.; Hanretty, C.; Harrison, N.; Hattawy, M.; Hicks, K.; Ho, D.; Holtrop, M.; Hyde, C. E.; Ilieva, Y.; Ireland, D. G.; Ishkhanov, B. S.; Jenkins, D.; Jo, H. S.; Joo, K.; Keller, D.; Khandaker, M.; Kim, A.; Kim, W.; Klein, A.; Klein, F. J.; Koirala, S.; Kubarovsky, V.; Kuhn, S. E.; Kuleshov, S. V.; Lenisa, P.; Livingston, K.; Lu, H.; MacGregor, I. J.D.; Markov, N.; Mayer, M.; McCracken, M. E.; McKinnon, B.; Mineeva, T.; Mirazita, M.; Mokeev, V.; Montgomery, R. A.; Moriya, K.; Moutarde, H.; Munevar, E.; Munoz Camacho, C.; Nadel-Turonski, P.; Niccolai, S.; Niculescu, G.; Niculescu, I.; Osipenko, M.; Pappalardo, L. L.; Paremuzyan, R.; Park, K.; Pasyuk, E.; Peng, P.; Phillips, J. J.; Pisano, S.; Pogorelko, O.; Pozdniakov, S.; Price, J. W.; Procureur, S.; Protopopescu, D.; Puckett, A. J. R.; Rimal, D.; Ripani, M.; Ritchie, B. G.; Rizzo, A.; Rossi, P.; Roy, P.; Sabatié, F.; Saini, M. S.; Schott, D.; Schumacher, R. A.; Seder, E.; Senderovich, I.; Sharabian, Y. G.; Simonyan, A.; Smith, E. S.; Sober, D. I.; Sokhan, D.; Stepanyan, S. S.; Stoler, P.; Strakovsky, I. I.; Strauch, S.; Sytnik, V.; Taiuti, M.; Tang, W.; Tkachenko, S.; Ungaro, M.; Vernarsky, B.; Vlassov, A. V.; Voskanyan, H.; Voutier, E.; Watts, D. P.; Zachariou, N.; Zana, L.; Zhang, J.; Zhao, Z. W.; Zonta, I.

    2014-05-27

    High-statistics measurements of differential cross sections and spin density matrix elements for the reaction γ p → Φp have been made using the CLAS detector at Jefferson Lab. We cover center-of-mass energies (√s) from 1.97 to 2.84 GeV, with an extensive coverage in the Φ production angle. The high statistics of the data sample made it necessary to carefully account for the interplay between the Φ natural lineshape and effects of the detector resolution, that are found to be comparable in magnitude. We study both the charged- (Φ → K⁺K⁻) and neutral- (Φ → K0SK0L) $K\\bar{K}$ decay modes of the Φ. Further, for the charged mode, we differentiate between the cases where the final K⁻ track is directly detected or its momentum reconstructed as the total missing momentum in the event. The two charged-mode topologies and the neutral-mode have different resolutions and are calibrated against each other. Extensive usage is made of kinematic fitting to improve the reconstructed Φ mass resolution. Our final results are reported in 10- and mostly 30-MeV-wide √s bins for the charged- and the neutral-mode, respectively. Possible effects from K⁺Λ* channels with p$K\\bar{K}$ final-states are discussed. These present results constitute the most precise and extensive Φ photoproduction measurements to date and in conjunction with the ω photoproduction results recently published by CLAS, will greatly improve our understanding of low energy vector meson photoproduction.

  2. Lesion-induced DNA weak structural changes detected by pulsed EPR spectroscopy combined with site-directed spin labelling

    PubMed Central

    Sicoli, Giuseppe; Mathis, Gérald; Aci-Sèche, Samia; Saint-Pierre, Christine; Boulard, Yves; Gasparutto, Didier; Gambarelli, Serge

    2009-01-01

    Double electron-electron resonance (DEER) was applied to determine nanometre spin–spin distances on DNA duplexes that contain selected structural alterations. The present approach to evaluate the structural features of DNA damages is thus related to the interspin distance changes, as well as to the flexibility of the overall structure deduced from the distance distribution. A set of site-directed nitroxide-labelled double-stranded DNA fragments containing defined lesions, namely an 8-oxoguanine, an abasic site or abasic site analogues, a nick, a gap and a bulge structure were prepared and then analysed by the DEER spectroscopic technique. New insights into the application of 4-pulse DEER sequence are also provided, in particular with respect to the spin probes’ positions and the rigidity of selected systems. The lesion-induced conformational changes observed, which were supported by molecular dynamics studies, confirm the results obtained by other, more conventional, spectroscopic techniques. Thus, the experimental approaches described herein provide an efficient method for probing lesion-induced structural changes of nucleic acids. PMID:19304747

  3. Spectroscopic Low Coherence Interferometry

    NASA Astrophysics Data System (ADS)

    Bosschaart, Nienke; van Leeuwen, T. G.; Aalders, Maurice C.; Hermann, Boris; Drexler, Wolfgang; Faber, Dirk J.

    Low-coherence interferometry (LCI) allows high-resolution volumetric imaging of tissue morphology and provides localized optical properties that can be related to the physiological status of tissue. This chapter discusses the combination of spatial and spectroscopic information by means of spectroscopic OCT (sOCT) and low-coherence spectroscopy (LCS). We describe the theory behind these modalities for the assessment of spatially resolved optical absorption and (back)scattering coefficient spectra. These spectra can be used for the highly localized quantification of chromophore concentrations and assessment of tissue organization on (sub)cellular scales. This leads to a wealth of potential clinical applications, ranging from neonatology for the determination of billibrubin concentrations, to oncology for the optical assessment of the aggressiveness of a cancerous lesion.

  4. Spectroscopic Binary Stars

    NASA Astrophysics Data System (ADS)

    Batten, A.; Murdin, P.

    2000-11-01

    Historically, spectroscopic binary stars were binary systems whose nature was discovered by the changing DOPPLER EFFECT or shift of the spectral lines of one or both of the component stars. The observed Doppler shift is a combination of that produced by the constant RADIAL VELOCITY (i.e. line-of-sight velocity) of the center of mass of the whole system, and the variable shift resulting from the o...

  5. Paramagnetic and Antiferromagnetic Spin Seebeck Effect

    NASA Astrophysics Data System (ADS)

    Wu, Stephen

    We report on the observation of the longitudinal spin Seebeck effect in both antiferromagnetic and paramagnetic insulators. By using a microscale on-chip local heater, it is possible to generate a large thermal gradient confined to the chip surface without a large increase in the total sample temperature. This technique allows us to easily access low temperatures (200 mK) and high magnetic fields (14 T) through conventional dilution refrigeration and superconducting magnet setups. By exploring this regime, we detect the spin Seebeck effect through the spin-flop transition in antiferromagnetic MnF2 when a large magnetic field (>9 T) is applied along the easy axis direction. Using the same technique, we are also able to resolve a spin Seebeck effect from the paramagnetic phase of geometrically frustrated antiferromagnet Gd3Ga5O12 (gadolinium gallium garnet) and antiferromagnetic DyScO3 (DSO). Since these measurements occur above the ordering temperatures of these two materials, short-range magnetic order is implicated as the cause of the spin Seebeck effect in these systems. The discovery of the spin Seebeck effect in these two materials classes suggest that both antiferromagnetic spin waves and spin excitations from short range magnetic order may be used to generate spin current from insulators and that the spin wave spectra of individual materials are highly important to the specifics of the longitudinal spin Seebeck effect. Since insulating antiferromagnets and paramagnets are far more common than the typical insulating ferrimagnetic materials used in spin Seebeck experiments, this discovery opens up a large new class of materials for use in spin caloritronic devices. All authors acknowledge support of the U.S. Department of Energy (DOE), Office of Science, Basic Energy Sciences (BES), Materials Sciences and Engineering Division. The use of facilities at the Center for Nanoscale Materials, was supported by the U.S. DOE, BES under Contract No. DE-AC02-06CH11357.

  6. Electrical detection of coherent spin precession using the ballistic intrinsic spin Hall effect.

    PubMed

    Choi, Won Young; Kim, Hyung-jun; Chang, Joonyeon; Han, Suk Hee; Koo, Hyun Cheol; Johnson, Mark

    2015-08-01

    The spin-orbit interaction in two-dimensional electron systems provides an exceptionally rich area of research. Coherent spin precession in a Rashba effective magnetic field in the channel of a spin field-effect transistor and the spin Hall effect are the two most compelling topics in this area. Here, we combine these effects to provide a direct demonstration of the ballistic intrinsic spin Hall effect and to demonstrate a technique for an all-electric measurement of the Datta-Das conductance oscillation, that is, the oscillation in the source-drain conductance due to spin precession. Our hybrid device has a ferromagnet electrode as a spin injector and a spin Hall detector. Results from multiple devices with different channel lengths map out two full wavelengths of the Datta-Das oscillation. We also use the original Datta-Das technique with a single device of fixed length and measure the channel conductance as the gate voltage is varied. Our experiments show that the ballistic spin Hall effect can be used for efficient injection or detection of spin polarized electrons, thereby enabling the development of an integrated spin transistor.

  7. Electrical detection of coherent spin precession using the ballistic intrinsic spin Hall effect

    NASA Astrophysics Data System (ADS)

    Choi, Won Young; Kim, Hyung-Jun; Chang, Joonyeon; Han, Suk Hee; Koo, Hyun Cheol; Johnson, Mark

    2015-08-01

    The spin-orbit interaction in two-dimensional electron systems provides an exceptionally rich area of research. Coherent spin precession in a Rashba effective magnetic field in the channel of a spin field-effect transistor and the spin Hall effect are the two most compelling topics in this area. Here, we combine these effects to provide a direct demonstration of the ballistic intrinsic spin Hall effect and to demonstrate a technique for an all-electric measurement of the Datta-Das conductance oscillation, that is, the oscillation in the source-drain conductance due to spin precession. Our hybrid device has a ferromagnet electrode as a spin injector and a spin Hall detector. Results from multiple devices with different channel lengths map out two full wavelengths of the Datta-Das oscillation. We also use the original Datta-Das technique with a single device of fixed length and measure the channel conductance as the gate voltage is varied. Our experiments show that the ballistic spin Hall effect can be used for efficient injection or detection of spin polarized electrons, thereby enabling the development of an integrated spin transistor.

  8. Random SU(2)-symmetric spin-S chains

    NASA Astrophysics Data System (ADS)

    Quito, V. L.; Hoyos, José A.; Miranda, E.

    2016-08-01

    We study the low-energy physics of a broad class of time-reversal invariant and SU(2)-symmetric one-dimensional spin-S systems in the presence of quenched disorder via a strong-disorder renormalization-group technique. We show that, in general, there is an antiferromagnetic phase with an emergent SU (2 S +1 ) symmetry. The ground state of this phase is a random singlet state in which the singlets are formed by pairs of spins. For integer spins, there is an additional antiferromagnetic phase which does not exhibit any emergent symmetry (except for S =1 ). The corresponding ground state is a random singlet one but the singlets are formed mostly by trios of spins. In each case the corresponding low-energy dynamics is activated, i.e., with a formally infinite dynamical exponent, and related to distinct infinite-randomness fixed points. The phase diagram has two other phases with ferromagnetic tendencies: a disordered ferromagnetic phase and a large spin phase in which the effective disorder is asymptotically finite. In the latter case, the dynamical scaling is governed by a conventional power law with a finite dynamical exponent.

  9. Nuclear spin circular dichroism

    SciTech Connect

    Vaara, Juha; Rizzo, Antonio; Kauczor, Joanna; Norman, Patrick; Coriani, Sonia

    2014-04-07

    Recent years have witnessed a growing interest in magneto-optic spectroscopy techniques that use nuclear magnetization as the source of the magnetic field. Here we present a formulation of magnetic circular dichroism (CD) due to magnetically polarized nuclei, nuclear spin-induced CD (NSCD), in molecules. The NSCD ellipticity and nuclear spin-induced optical rotation (NSOR) angle correspond to the real and imaginary parts, respectively, of (complex) quadratic response functions involving the dynamic second-order interaction of the electron system with the linearly polarized light beam, as well as the static magnetic hyperfine interaction. Using the complex polarization propagator framework, NSCD and NSOR signals are obtained at frequencies in the vicinity of optical excitations. Hartree-Fock and density-functional theory calculations on relatively small model systems, ethene, benzene, and 1,4-benzoquinone, demonstrate the feasibility of the method for obtaining relatively strong nuclear spin-induced ellipticity and optical rotation signals. Comparison of the proton and carbon-13 signals of ethanol reveals that these resonant phenomena facilitate chemical resolution between non-equivalent nuclei in magneto-optic spectra.

  10. Theory of spin blockade in a triple quantum dots

    NASA Astrophysics Data System (ADS)

    Hsieh, Chang-Yu; Shim, Yun-Pil; Hawrylak, Pawel

    2011-03-01

    We present a theory of electronic properties and spin blockade in a linear triple quantum dots. We use micoroscopic LCHO-CI and double-band Hubbard model to analyze the electronic and spin properties of a triple quantum dots near a symmetrical quadruple point involving the (1,1,1) configuration which is essential for implementing quantum information processing with electron spin. We calculate spectral functions and relate them via the rate equation, including coupling with a phonon bath, to current as a function of applied bias. We show that the spin blockade in a triple quantum dots can serve as a spectroscopic tool to distinguish spin polarized states from spin depolarized states. We also show that a spin blockade is developed only at high bias when an onsite triplet state on the edge quantum dot connected to the source lead becomes accessible in the transport window. In contradiction to the case of double quantum dot molecule, the onsite triplet is not only essential for lifting spin blockade but also important for building up spin polarisation and spin blockade in the system. The authors would like to acknowledge financial support from NSERC, OGS, and QuantumWorks.

  11. Anisotropic Spin Hall Effect from First Principles

    NASA Astrophysics Data System (ADS)

    Freimuth, Frank; Blügel, Stefan; Mokrousov, Yuriy

    2011-03-01

    We present first principles calculations of the intrinsic non-dissipative spin Hall conductivity (SHC) for 3 d , 4 d and 5 d transition metals focusing in particular on the anisotropy of the SHC in nonmagnetic hcp metals and in antiferromagnetic Cr. For the metals of this study we generally find large anisotropies. We derive the general relation between the SHC vector and the direction of spin-polarization and discuss its consequences for hcp metals. Especially, it is predicted that for systems where the SHC changes sign due to the anisotropy the spin Hall effect may be tuned such that the spin polarization is parallel either to the electric field or to the spin current. Additionally, we describe our computational method [2,3] emphasizing the Wannier interpolation technique and the definition of the conserved spin current. This work is supported by the DFG Project MO 1731/3-1 and HGF-YIG grant VH-NG-513.

  12. Spinning targets for laser fusion

    SciTech Connect

    Baldwin, D.E.; Ryutov, D.D.

    1995-09-01

    Several techniques for spinning the ICF targets up prior to or in the course of their compression are suggested. Interference of the rotational shear flow with Rayleigh-Taylor instability is briefly discussed and possible consequences for the target performance are pointed out.

  13. Diradicals acting through diamagnetic phenylene vinylene bridges: Raman spectroscopy as a probe to characterize spin delocalization.

    PubMed

    González, Sandra Rodríguez; Nieto-Ortega, Belén; González Cano, Rafael C; Lloveras, Vega; Novoa, Juan J; Mota, Fernando; Vidal-Gancedo, José; Rovira, Concepció; Veciana, Jaume; del Corro, Elena; Taravillo, Mercedes; Baonza, Valentín G; López Navarrete, Juan T; Casado, Juan

    2014-04-28

    We present a complete Raman spectroscopic study in two structurally well-defined diradical species of different lengths incorporating oligo p-phenylene vinylene bridges between two polychlorinated triphenylmethyl radical units, a disposition that allows sizeable conjugation between the two radicals through and with the bridge. The spectroscopic data are interpreted and supported by quantum chemical calculations. We focus the attention on the Raman frequency changes, interpretable in terms of: (i) bridge length (conjugation length); (ii) bridge conformational structure; and (iii) electronic coupling between the terminal radical units with the bridge and through the bridge, which could delineate through-bond spin polarization, or spin delocalization. These items are addressed by using the "oligomer approach" in conjunction with pressure and temperature dependent Raman spectroscopic data. In summary, we have attempted to translate the well-known strategy to study the electron (charge) structure of π-conjugated molecules by Raman spectroscopy to the case of electron (spin) interactions via the spin delocalization mechanism.

  14. Electron spin resonance and spin-valley physics in a silicon double quantum dot.

    PubMed

    Hao, Xiaojie; Ruskov, Rusko; Xiao, Ming; Tahan, Charles; Jiang, HongWen

    2014-05-14

    Silicon quantum dots are a leading approach for solid-state quantum bits. However, developing this technology is complicated by the multi-valley nature of silicon. Here we observe transport of individual electrons in a silicon CMOS-based double quantum dot under electron spin resonance. An anticrossing of the driven dot energy levels is observed when the Zeeman and valley splittings coincide. A detected anticrossing splitting of 60 MHz is interpreted as a direct measure of spin and valley mixing, facilitated by spin-orbit interaction in the presence of non-ideal interfaces. A lower bound of spin dephasing time of 63 ns is extracted. We also describe a possible experimental evidence of an unconventional spin-valley blockade, despite the assumption of non-ideal interfaces. This understanding of silicon spin-valley physics should enable better control and read-out techniques for the spin qubits in an all CMOS silicon approach.

  15. Long-range spin-triplet correlations and edge spin currents in diffusive spin-orbit coupled SNS hybrids with a single spin-active interface

    NASA Astrophysics Data System (ADS)

    Alidoust, Mohammad; Halterman, Klaus

    2015-06-01

    Utilizing a SU(2) gauge symmetry technique in the quasiclassical diffusive regime, we theoretically study finite-sized two-dimensional intrinsic spin-orbit coupled superconductor/normal-metal/superconductor (S/N/S) hybrid structures with a single spin-active interface. We consider intrinsic spin-orbit interactions (ISOIs) that are confined within the N wire and absent in the s-wave superconducting electrodes (S). Using experimentally feasible parameters, we demonstrate that the coupling of the ISOIs and spin moment of the spin-active interface results in maximum singlet-triplet conversion and accumulation of spin current density at the corners of the N wire nearest the spin-active interface. By solely modulating the superconducting phase difference, we show how the opposing parities of the charge and spin currents provide an effective venue to experimentally examine pure edge spin currents not accompanied by charge currents. These effects occur in the absence of externally imposed fields and moreover are insensitive to the arbitrary orientations of the interface spin moment. The experimental implementation of these robust edge phenomena are also discussed.

  16. THIRTY NEW LOW-MASS SPECTROSCOPIC BINARIES

    SciTech Connect

    Shkolnik, Evgenya L.; Hebb, Leslie; Cameron, Andrew C.; Liu, Michael C.; Neill Reid, I. E-mail: Andrew.Cameron@st-and.ac.u E-mail: mliu@ifa.hawaii.ed

    2010-06-20

    As part of our search for young M dwarfs within 25 pc, we acquired high-resolution spectra of 185 low-mass stars compiled by the NStars project that have strong X-ray emission. By cross-correlating these spectra with radial velocity standard stars, we are sensitive to finding multi-lined spectroscopic binaries. We find a low-mass spectroscopic binary fraction of 16% consisting of 27 SB2s, 2 SB3s, and 1 SB4, increasing the number of known low-mass spectroscopic binaries (SBs) by 50% and proving that strong X-ray emission is an extremely efficient way to find M-dwarf SBs. WASP photometry of 23 of these systems revealed two low-mass eclipsing binaries (EBs), bringing the count of known M-dwarf EBs to 15. BD-22 5866, the ESB4, was fully described in 2008 by Shkolnik et al. and CCDM J04404+3127 B consists of two mid-M stars orbiting each other every 2.048 days. WASP also provided rotation periods for 12 systems, and in the cases where the synchronization time scales are short, we used P{sub rot} to determine the true orbital parameters. For those with no P{sub rot}, we used differential radial velocities to set upper limits on orbital periods and semimajor axes. More than half of our sample has near-equal-mass components (q > 0.8). This is expected since our sample is biased toward tight orbits where saturated X-ray emission is due to tidal spin-up rather than stellar youth. Increasing the samples of M-dwarf SBs and EBs is extremely valuable in setting constraints on current theories of stellar multiplicity and evolution scenarios for low-mass multiple systems.

  17. LIBS spectroscopic classification relative to compressive sensing

    NASA Astrophysics Data System (ADS)

    Griffin, Steven T.; Jacobs, Eddie; Furxhi, Orges

    2011-05-01

    Laser Induced Breakdown Spectroscopy (LIBS) utilizes a diversity of standard spectroscopic techniques for classification of materials present in the sample. Pre-excitation processing sometimes limits the analyte to a short list of candidates. Prior art demonstrates that sparsity is present in the data. This is sometimes characterized as identification by components. Traditionally, spectroscopic identification has been accomplished by an expert reader in a manner typical for MRI images in the medicine. In an effort to automate this process, more recent art has emphasized the use of customized variations to standard classification algorithms. In addition, formal mathematical proofs for compressive sensing have been advanced. Recently the University of Memphis has been contracted by the Spectroscopic Materials Identification Center to advance and characterize the sensor research and development related to LIBS. Applications include portable standoff sensing for improvised explosive device detection and related law enforcement and military applications. Reduction of the mass, power consumption and other portability parameters is seen as dependent on classification choices for a LIBS system. This paper presents results for the comparison of standard LIBS classification techniques to those implied by Compressive Sensing mathematics. Optimization results and implications for portable LIBS design are presented.

  18. Flux measurements using the BATSE spectroscopic detectors

    NASA Technical Reports Server (NTRS)

    Mcnamara, Bernard

    1993-01-01

    Among the Compton Gama-Ray Observatory instruments, the BATSE Spectroscopic Detectors (SD) have the distinction of being able to detect photons of energies less than about 20 keV. This is an interesting energy range for the examination of low mass X-ray binaries (LMXB's). In fact, Sco X-1, the prototype LMXB, is easily seen even in the raw BATSE spectroscopic data. The all-sky coverage afforded by these detectors offers a unique opportunity to monitor this source over time periods never before possible. The aim of this investigation was to test a number of ways in which both continous and discrete flux measurements can be obtained using the BATSE spectroscopic datasets. A instrumental description of a SD can be found in the Compton Workshop of Apr. 1989, this report will deal only with methods which can be used to analyze its datasets. Many of the items discussed below, particularly in regard to the earth occultation technique, have been developed, refined, and applied by the BATSE team to the reduction of BATSE LAD data. Code written as part of this project utilizes portions of that work. The following discussions will first address issues related to the reduction of SD datasets using the earth occultation technique. It will then discuss methods for the recovery of the flux history of strong sources while they are above the earth's limb. The report will conclude with recommended reduction procedures.

  19. Spectroscopic studies of individual plasmon resonant nanoparticles

    NASA Astrophysics Data System (ADS)

    Mock, Jack J.; Smith, David R.; Barbic, Mladen; Oldenburg, Steven J.; Schultz, David A.; Schultz, Sheldon

    2003-11-01

    We present a detailed description of the apparatus and techniques that we have utilized in our experimental study of individual plas on resonant nanoparticles,along with a brief description of some major results. The apparatus consists of a spectroscopic system combined with a modified darkfield microscope, which enables the user to sequentially select individual resonant nanostructures in the microscopic field of view for spectroscopic study. Plasmon resonant nanostructures scatter light elastically,and typically have very large scattering cross-sections at their resonant optical wavelengths. In general, spectra can be obtained with acquisition times between .1 to 30 seconds,and color images can be captured using consumer digital color cameras. Spheres,tetrahedrons,and pentagonal platelets were fabricated using colloidal chemistry techniques. To produce highly anisotropic structures such as nanorods and "barbells", templates were used. Many of these nanostructures have been individually spectroscopically characterized,and their spectra correlated with their shape and size as determined by transmission electron icroscope (TEM). The unique shape,size, composition,and dielectric surroundings of the individual plasmon resonant nanostructures determine their plasmon resonant behavior. We will show how the composition of the substrate on which the particles are immobilized and the dielectric of the surrounding medium have a significant effect on the plasmon resonance of the individual particles.

  20. The spin Hall effect in a quantum gas.

    PubMed

    Beeler, M C; Williams, R A; Jiménez-García, K; LeBlanc, L J; Perry, A R; Spielman, I B

    2013-06-13

    Electronic properties such as current flow are generally independent of the electron's spin angular momentum, an internal degree of freedom possessed by quantum particles. The spin Hall effect, first proposed 40 years ago, is an unusual class of phenomena in which flowing particles experience orthogonally directed, spin-dependent forces--analogous to the conventional Lorentz force that gives the Hall effect, but opposite in sign for two spin states. Spin Hall effects have been observed for electrons flowing in spin-orbit-coupled materials such as GaAs and InGaAs (refs 2, 3) and for laser light traversing dielectric junctions. Here we observe the spin Hall effect in a quantum-degenerate Bose gas, and use the resulting spin-dependent Lorentz forces to realize a cold-atom spin transistor. By engineering a spatially inhomogeneous spin-orbit coupling field for our quantum gas, we explicitly introduce and measure the requisite spin-dependent Lorentz forces, finding them to be in excellent agreement with our calculations. This 'atomtronic' transistor behaves as a type of velocity-insensitive adiabatic spin selector, with potential application in devices such as magnetic or inertial sensors. In addition, such techniques for creating and measuring the spin Hall effect are clear prerequisites for engineering topological insulators and detecting their associated quantized spin Hall effects in quantum gases. As implemented, our system realizes a laser-actuated analogue to the archetypal semiconductor spintronic device, the Datta-Das spin transistor.

  1. Quasiparticle spin resonance and coherence in superconducting aluminium

    NASA Astrophysics Data System (ADS)

    Quay, C. H. L.; Weideneder, M.; Chiffaudel, Y.; Strunk, C.; Aprili, M.

    2015-10-01

    Conventional superconductors were long thought to be spin inert; however, there is now increasing interest in both (the manipulation of) the internal spin structure of the ground-state condensate, as well as recently observed long-lived, spin-polarized excitations (quasiparticles). We demonstrate spin resonance in the quasiparticle population of a mesoscopic superconductor (aluminium) using novel on-chip microwave detection techniques. The spin decoherence time obtained (~100 ps), and its dependence on the sample thickness are consistent with Elliott-Yafet spin-orbit scattering as the main decoherence mechanism. The striking divergence between the spin coherence time and the previously measured spin imbalance relaxation time (~10 ns) suggests that the latter is limited instead by inelastic processes. This work stakes out new ground for the nascent field of spin-based electronics with superconductors or superconducting spintronics.

  2. Infrared spectroscopy and spectroscopic imaging in forensic science.

    PubMed

    Ewing, Andrew V; Kazarian, Sergei G

    2017-01-16

    Infrared spectroscopy and spectroscopic imaging, are robust, label free and inherently non-destructive methods with a high chemical specificity and sensitivity that are frequently employed in forensic science research and practices. This review aims to discuss the applications and recent developments of these methodologies in this field. Furthermore, the use of recently emerged Fourier transform infrared (FT-IR) spectroscopic imaging in transmission, external reflection and Attenuated Total Reflection (ATR) modes are summarised with relevance and potential for forensic science applications. This spectroscopic imaging approach provides the opportunity to obtain the chemical composition of fingermarks and information about possible contaminants deposited at a crime scene. Research that demonstrates the great potential of these techniques for analysis of fingerprint residues, explosive materials and counterfeit drugs will be reviewed. The implications of this research for the examination of different materials are considered, along with an outlook of possible future research avenues for the application of vibrational spectroscopic methods to the analysis of forensic samples.

  3. Quantum Spin Fluctuations for a Distorted Incommensurate Spiral

    SciTech Connect

    Fishman, Randy Scott

    2012-01-01

    Quantum spin fluctuations are investigated for the incommensurate state of a geometrically- frustrated triangular-lattice antiferromagnet. With increasing anisotropy, the average suppression of the spin by quantum fluctuations is reduced but the distorted spiral becomes more elliptical. Quan- tum fluctuations also increase the wavevector of the spin state and enhance the critical anisotropy above which a collinear spin state is stabilized. An experimental technique is proposed to isolate the effect of quantum fluctuations from the classical distortion of the spiral.

  4. Electronic, magnetic and spectroscopic properties of manganese nanostructures

    NASA Astrophysics Data System (ADS)

    Demangeat, C.; Parlebas, J. C.

    2002-11-01

    This paper presents a review of the electronic, magnetic and spectroscopic properties of manganese (Mn)-based nanostructures. In the last few years a variety of techniques have been used to prepare mesoscopic transition-metal islands and novel effects associated with the electronic structure in nanoscale systems have been reported. Mn in the atomic configuration possesses a moment as high as 5μB so it should be very interesting to dope semiconductors with Mn for spin injection or to use Mn itself for permanent magnets. In this paper the introduction (section 1) focuses mainly on metallic Mn nanostructures which are the core of this review. Nevertheless we try to present a general overview of various kinds of Mn structures as well as several theoretical methods with their own limitations to handle the corresponding problems. More precisely, section 2 outlines a variety of bulk, surface, interface and cluster structures with their resulting magnetism as far as Mn is concerned. Actually, in these past two decades, considerable interest has been devoted to Mn nanostructures deposited on various metallic substrates (section 3). Because of its exotic structural and magnetic properties, Mn is indeed an interesting candidate for ultra-thin film growth as it is expected to accept different local configurations. Experimentally, one may attempt to stabilize normally high-temperature phases of Mn by epitaxial growth on a suitable substrate. Specifically, we shall point out the frequently occurring, important situation of magnetically stabilized surface alloys. Next (section 4) we first focus on spectroscopic properties of Mn compounds as well as Mn adsorbates upon graphite and other substrates both experimentally and theoretically. Moreover, we recall a few remarks about Mn impurities with respect to the Kondo problem and also with respect to semiconductors and spintronics. In the latter field, practical applications actually require room-temperature Mn ferromagnetism which

  5. Cross-correlation spin noise spectroscopy of heterogeneous interacting spin systems

    SciTech Connect

    Roy, Dibyendu; Yang, Luyi; Crooker, Scott A.; Sinitsyn, Nikolai A.

    2015-04-30

    Interacting multi-component spin systems are ubiquitous in nature and in the laboratory. As such, investigations of inter-species spin interactions are of vital importance. Traditionally, they are studied by experimental methods that are necessarily perturbative: e.g., by intentionally polarizing or depolarizing one spin species while detecting the response of the other(s). Here, we describe and demonstrate an alternative approach based on multi-probe spin noise spectroscopy, which can reveal inter-species spin interactions - under conditions of strict thermal equilibrium - by detecting and cross-correlating the stochastic fluctuation signals exhibited by each of the constituent spin species. Specifically, we consider a two-component spin ensemble that interacts via exchange coupling, and we determine cross-correlations between their intrinsic spin fluctuations. The model is experimentally confirmed using “two-color” optical spin noise spectroscopy on a mixture of interacting Rb and Cs vapors. Noise correlations directly reveal the presence of inter-species spin exchange, without ever perturbing the system away from thermal equilibrium. These non-invasive and noise-based techniques should be generally applicable to any heterogeneous spin system in which the fluctuations of the constituent components are detectable.

  6. Spin-orbit ferromagnetic resonance

    NASA Astrophysics Data System (ADS)

    Ferguson, Andrew

    2013-03-01

    In conventional magnetic resonance techniques the magnitude and direction of the oscillatory magnetic field are (at least approximately) known. This oscillatory field is used to probe the properties of a spin ensemble. Here, I will describe experiments that do the inverse. I will discuss how we use a magnetic resonance technique to map out the current-induced effective magnetic fields in the ferromagnetic semiconductors (Ga,Mn)As and (Ga,Mn)(As,P). These current-induced fields have their origin in the spin-orbit interaction. Effective magnetic fields are observed with symmetries which resemble the Dresselhaus and Rashba spin-orbit interactions and which depend on the diagonal and off-diagonal strain respectively. Ferromagnetic semiconductor materials of different strains, annealing conditions and concentrations are studied and the results compared with theoretical calculations. Our original study measured the rectification voltage coming from the product of the oscillatory magnetoresistance, during magnetisation precession, and the alternating current. More recently we have developed an impedance matching technique which enables us to extract microwave voltages from these high resistance (10 k Ω) samples. In this way we measure the microwave voltage coming from the product of the oscillating magneto-resistance and a direct current. The direct current is observed to affect the magnetisation precession, indicating that anti-damping as well as field-like torques can originate from the spin-orbit interaction.

  7. Spin-Spin Coupling in Asteroidal Binaries

    NASA Astrophysics Data System (ADS)

    Batygin, Konstantin; Morbidelli, Alessandro

    2015-11-01

    Gravitationally bound binaries constitute a substantial fraction of the small body population of the solar system, and characterization of their rotational states is instrumental to understanding their formation and dynamical evolution. Unlike planets, numerous small bodies can maintain a perpetual aspheroidal shape, giving rise to a richer array of non-trivial gravitational dynamics. In this work, we explore the rotational evolution of triaxial satellites that orbit permanently deformed central objects, with specific emphasis on quadrupole-quadrupole interactions. Our analysis shows that in addition to conventional spin-orbit resonances, both prograde and retrograde spin-spin resonances naturally arise for closely orbiting, highly deformed bodies. Application of our results to the illustrative examples of (87) Sylvia and (216) Kleopatra multi-asteroid systems implies capture probabilities slightly below ~10% for leading-order spin-spin resonances. Cumulatively, our results suggest that spin-spin coupling may be consequential for highly elongated, tightly orbiting binary objects.

  8. Adiabatic quantum computing with spin qubits hosted by molecules.

    PubMed

    Yamamoto, Satoru; Nakazawa, Shigeaki; Sugisaki, Kenji; Sato, Kazunobu; Toyota, Kazuo; Shiomi, Daisuke; Takui, Takeji

    2015-01-28

    A molecular spin quantum computer (MSQC) requires electron spin qubits, which pulse-based electron spin/magnetic resonance (ESR/MR) techniques can afford to manipulate for implementing quantum gate operations in open shell molecular entities. Importantly, nuclear spins, which are topologically connected, particularly in organic molecular spin systems, are client qubits, while electron spins play a role of bus qubits. Here, we introduce the implementation for an adiabatic quantum algorithm, suggesting the possible utilization of molecular spins with optimized spin structures for MSQCs. We exemplify the utilization of an adiabatic factorization problem of 21, compared with the corresponding nuclear magnetic resonance (NMR) case. Two molecular spins are selected: one is a molecular spin composed of three exchange-coupled electrons as electron-only qubits and the other an electron-bus qubit with two client nuclear spin qubits. Their electronic spin structures are well characterized in terms of the quantum mechanical behaviour in the spin Hamiltonian. The implementation of adiabatic quantum computing/computation (AQC) has, for the first time, been achieved by establishing ESR/MR pulse sequences for effective spin Hamiltonians in a fully controlled manner of spin manipulation. The conquered pulse sequences have been compared with the NMR experiments and shown much faster CPU times corresponding to the interaction strength between the spins. Significant differences are shown in rotational operations and pulse intervals for ESR/MR operations. As a result, we suggest the advantages and possible utilization of the time-evolution based AQC approach for molecular spin quantum computers and molecular spin quantum simulators underlain by sophisticated ESR/MR pulsed spin technology.

  9. Spin-1 quantum walks

    NASA Astrophysics Data System (ADS)

    Morita, Daichi; Kubo, Toshihiro; Tokura, Yasuhiro; Yamashita, Makoto

    2016-06-01

    We study the quantum walks of two interacting spin-1 bosons. We derive an exact solution for the time-dependent wave function, which describes the two-particle dynamics governed by the one-dimensional spin-1 Bose-Hubbard model. We show that propagation dynamics in real space and mixing dynamics in spin space are correlated via the spin-dependent interaction in this system. The spin-mixing dynamics has two characteristic frequencies in the limit of large spin-dependent interactions. One of the characteristic frequencies is determined by the energy difference between two bound states, and the other frequency relates to the cotunneling process of a pair of spin-1 bosons. Furthermore, we numerically analyze the growth of the spin correlations in quantum walks. We find that long-range spin correlations emerge showing a clear dependence on the sign of the spin-dependent interaction and the initial state.

  10. Vibrational spectroscopic characterization of fluoroquinolones

    NASA Astrophysics Data System (ADS)

    Neugebauer, U.; Szeghalmi, A.; Schmitt, M.; Kiefer, W.; Popp, J.; Holzgrabe, U.

    2005-05-01

    Quinolones are important gyrase inhibitors. Even though they are used as active agents in many antibiotics, the detailed mechanism of action on a molecular level is so far not known. It is of greatest interest to shed light on this drug-target interaction to provide useful information in the fight against growing resistances and obtain new insights for the development of new powerful drugs. To reach this goal, on a first step it is essential to understand the structural characteristics of the drugs and the effects that are caused by the environment in detail. In this work we report on Raman spectroscopical investigations of a variety of gyrase inhibitors (nalidixic acid, oxolinic acid, cinoxacin, flumequine, norfloxacin, ciprofloxacin, lomefloxacin, ofloxacin, enoxacin, sarafloxacin and moxifloxacin) by means of micro-Raman spectroscopy excited with various excitation wavelengths, both in the off-resonance region (532, 633, 830 and 1064 nm) and in the resonance region (resonance Raman spectroscopy at 244, 257 and 275 nm). Furthermore DFT calculations were performed to assign the vibrational modes, as well as for an identification of intramolecular hydrogen bonding motifs. The effect of small changes in the drug environment was studied by adding successively small amounts of water until physiological low concentrations of the drugs in aqueous solution were obtained. At these low concentrations resonance Raman spectroscopy proved to be a useful and sensitive technique. Supplementary information was obtained from IR and UV/vis spectroscopy.

  11. Spectroscopic properties of alexandrite crystals

    NASA Astrophysics Data System (ADS)

    Powell, Richard C.; Xi, Lin; Gang, Xu; Quarles, Gregory J.; Walling, John C.

    1985-09-01

    Details of the optical-spectroscopic properties of alexandrite (BeAl2O4:Cr3+) crystals were studied by different laser-spectroscopy techniques. The temperature dependences of the fluorescence lifetimes and widths of the zero-phonon lines were found to be quite different for Cr3+ ions in the mirror and inversion crystal-field sites. The results indicate that direct phonon-absorption processes dominate both thermal line broadening and lifetime quenching for ions in the mirror sites while phonon-scattering processes dominate the line broadening of inversion-site ions and leave their lifetime independent of temperature. Tunable-dye-laser site-selection methods were used to obtain the excitation spectra of the Cr3+ ions in inversion sites at low temperature and to identify six types of exchange-coupled pairs of Cr3+ ions in the lattice. Time-resolved site-selection spectroscopy was used to monitor the energy transfer between Cr3+ ions in mirror and inversion sites at both low and high temperature. Finally, high-power, picosecond pulse excitation was used to produce two-photon absorption, and the resulting emission spectrum was found to exhibit a new fluorescence band in the 400-nm spectral region.

  12. Spin state switching in iron coordination compounds

    PubMed Central

    Gaspar, Ana B; Garcia, Yann

    2013-01-01

    Summary The article deals with coordination compounds of iron(II) that may exhibit thermally induced spin transition, known as spin crossover, depending on the nature of the coordinating ligand sphere. Spin transition in such compounds also occurs under pressure and irradiation with light. The spin states involved have different magnetic and optical properties suitable for their detection and characterization. Spin crossover compounds, though known for more than eight decades, have become most attractive in recent years and are extensively studied by chemists and physicists. The switching properties make such materials potential candidates for practical applications in thermal and pressure sensors as well as optical devices. The article begins with a brief description of the principle of molecular spin state switching using simple concepts of ligand field theory. Conditions to be fulfilled in order to observe spin crossover will be explained and general remarks regarding the chemical nature that is important for the occurrence of spin crossover will be made. A subsequent section describes the molecular consequences of spin crossover and the variety of physical techniques usually applied for their characterization. The effects of light irradiation (LIESST) and application of pressure are subjects of two separate sections. The major part of this account concentrates on selected spin crossover compounds of iron(II), with particular emphasis on the chemical and physical influences on the spin crossover behavior. The vast variety of compounds exhibiting this fascinating switching phenomenon encompasses mono-, oligo- and polynuclear iron(II) complexes and cages, polymeric 1D, 2D and 3D systems, nanomaterials, and polyfunctional materials that combine spin crossover with another physical or chemical property. PMID:23504535

  13. Magnons, Spin Current and Spin Seebeck Effect

    NASA Astrophysics Data System (ADS)

    Maekawa, Sadamichi

    2012-02-01

    When metals and semiconductors are placed in a temperature gradient, the electric voltage is generated. This mechanism to convert heat into electricity, the so-called Seebeck effect, has attracted much attention recently as the mechanism for utilizing wasted heat energy. [1]. Ferromagnetic insulators are good conductors of spin current, i.e., the flow of electron spins [2]. When they are placed in a temperature gradient, generated are magnons, spin current and the spin voltage [3], i.e., spin accumulation. Once the spin voltage is converted into the electric voltage by inverse spin Hall effect in attached metal films such as Pt, the electric voltage is obtained from heat energy [4-5]. This is called the spin Seebeck effect. Here, we present the linear-response theory of spin Seebeck effect based on the fluctuation-dissipation theorem [6-8] and discuss a variety of the devices. [4pt] [1] S. Maekawa et al, Physics of Transition Metal Oxides (Springer, 2004). [0pt] [2] S. Maekawa: Nature Materials 8, 777 (2009). [0pt] [3] Concept in Spin Electronics, eds. S. Maekawa (Oxford University Press, 2006). [0pt] [4] K. Uchida et al., Nature 455, 778 (2008). [0pt] [5] K. Uchida et al., Nature Materials 9, 894 (2010) [0pt] [6] H. Adachi et al., APL 97, 252506 (2010) and Phys. Rev. B 83, 094410 (2011). [0pt] [7] J. Ohe et al., Phys. Rev. B (2011) [0pt] [8] K. Uchida et al., Appl. Phys. Lett. 97, 104419 (2010).

  14. Spin torque ferromagnetic resonance with magnetic field modulation

    NASA Astrophysics Data System (ADS)

    Gonçalves, A. M.; Barsukov, I.; Chen, Y.-J.; Yang, L.; Katine, J. A.; Krivorotov, I. N.

    2013-10-01

    We demonstrate a technique of broadband spin torque ferromagnetic resonance (ST-FMR) with magnetic field modulation for measurements of spin wave properties in magnetic nanostructures. This technique gives great improvement in sensitivity over the conventional ST-FMR measurements, and application of this technique to nanoscale magnetic tunnel junctions (MTJs) reveals a rich spectrum of standing spin wave eigenmodes. Comparison of the ST-FMR measurements with micromagnetic simulations of the spin wave spectrum allows us to explain the character of low-frequency magnetic excitations in nanoscale MTJs.

  15. Theoretical investigation of electronic states and spectroscopic properties of tellurium selenide molecule employing relativistic effective core potentials.

    PubMed

    Chattopadhyaya, Surya; Nath, Abhijit; Das, Kalyan Kumar

    2014-04-24

    Ab initio based relativistic configuration interaction calculations have been performed to study the electronic states and spectroscopic properties of tellurium selenide (TeSe) - the heaviest heteronuclear diatomic group 16-16 molecule. Potential energy curves of several spin-excluded (Λ-S) electronic states of TeSe have been constructed and spectroscopic constants of low-lying bound Λ-S states within 3.85 eV are reported in the first stage of calculations. The X(3)Σ(-), a(1)Δ and b(1)Σ(+) are found as the ground, first excited and second excited state, respectively, at the Λ-S level and all these three states are mainly dominated by …π(4)π(*2) configuration. The computed ground state dissociation energy is in very good agreement with the experimental results. In the next stage of calculations, effects of spin-orbit coupling on the potential energy curves and spectroscopic properties of the species are investigated in details and compared with the existing experimental results. After inclusion of spin-orbit coupling the X(3)(1)Σ(-)(0(+)) is found as the ground-state spin component of TeSe. The computed spin-orbit splitting between two components of X(3)Σ(-) state is 1285 cm(-1). Also, significant amount of spin-orbit splitting are found between spin-orbit components (Ω-components) of several other excited states. Transition moments of some important spin-allowed and spin-forbidden transitions are calculated from configuration interaction wave functions. The spin-allowed transition B(3)Σ(-)-X(3)Σ(-) and spin-forbidden transition b(1)Σ(+)(0(+))-X(3)(1)Σ(-)(0(+)) are found to be the strongest in their respective categories. Electric dipole moments of all the bound Λ-S states along with those of the two Ω-components of X(3)Σ(-) are also calculated in the present study.

  16. Spectroscopic Constants and Potential Energy Curves of PbI

    NASA Astrophysics Data System (ADS)

    Benavidesgarcia, M.; Balasubramanian, K.

    1993-10-01

    The spectroscopic constants and potential energy curves of the PbI diatomic were computed using complete active space SCF (CASSCF) followed by first-order CI (FOCI) and second-order CI (SOCI) calculations which included 607 000 configurations. Spin-orbit coupling was studied using the relativistic CI (RCI) method. The spectroscopic properties of the 2Π1/2 state are Re = 2.885 Å, ωe, = 153 cm-1, and De = 2.54(eV), while for the 2Π3/2 state the corresponding values are Re = 2.859 Å, ωe = 162 cm-1, and Te = 8255 cm-1. Our computed constants are in good agreement with experiment for the observed states. We also computed the properties and curves for several excited states which are yet to be observed.

  17. Cross-correlation spin noise spectroscopy of heterogeneous interacting spin systems

    DOE PAGES

    Roy, Dibyendu; Yang, Luyi; Crooker, Scott A.; ...

    2015-04-30

    Interacting multi-component spin systems are ubiquitous in nature and in the laboratory. As such, investigations of inter-species spin interactions are of vital importance. Traditionally, they are studied by experimental methods that are necessarily perturbative: e.g., by intentionally polarizing or depolarizing one spin species while detecting the response of the other(s). Here, we describe and demonstrate an alternative approach based on multi-probe spin noise spectroscopy, which can reveal inter-species spin interactions - under conditions of strict thermal equilibrium - by detecting and cross-correlating the stochastic fluctuation signals exhibited by each of the constituent spin species. Specifically, we consider a two-component spinmore » ensemble that interacts via exchange coupling, and we determine cross-correlations between their intrinsic spin fluctuations. The model is experimentally confirmed using “two-color” optical spin noise spectroscopy on a mixture of interacting Rb and Cs vapors. Noise correlations directly reveal the presence of inter-species spin exchange, without ever perturbing the system away from thermal equilibrium. These non-invasive and noise-based techniques should be generally applicable to any heterogeneous spin system in which the fluctuations of the constituent components are detectable.« less

  18. Spectroscopic methods in gas hydrate research.

    PubMed

    Rauh, Florian; Mizaikoff, Boris

    2012-01-01

    Gas hydrates are crystalline structures comprising a guest molecule surrounded by a water cage, and are particularly relevant due to their natural occurrence in the deep sea and in permafrost areas. Low molecular weight molecules such as methane and carbon dioxide can be sequestered into that cage at suitable temperatures and pressures, facilitating the transition to the solid phase. While the composition and structure of gas hydrates appear to be well understood, their formation and dissociation mechanisms, along with the dynamics and kinetics associated with those processes, remain ambiguous. In order to take advantage of gas hydrates as an energy resource (e.g., methane hydrate), as a sequestration matrix in (for example) CO(2) storage, or for chemical energy conservation/storage, a more detailed molecular level understanding of their formation and dissociation processes, as well as the chemical, physical, and biological parameters that affect these processes, is required. Spectroscopic techniques appear to be most suitable for analyzing the structures of gas hydrates (sometimes in situ), thus providing access to such information across the electromagnetic spectrum. A variety of spectroscopic methods are currently used in gas hydrate research to determine the composition, structure, cage occupancy, guest molecule position, and binding/formation/dissociation mechanisms of the hydrate. To date, the most commonly applied techniques are Raman spectroscopy and solid-state nuclear magnetic resonance (NMR) spectroscopy. Diffraction methods such as neutron and X-ray diffraction are used to determine gas hydrate structures, and to study lattice expansions. Furthermore, UV-vis spectroscopic techniques and scanning electron microscopy (SEM) have assisted in structural studies of gas hydrates. Most recently, waveguide-coupled mid-infrared spectroscopy in the 3-20 μm spectral range has demonstrated its value for in situ studies on the formation and dissociation of gas

  19. Optical detection of spin Hall effect in metals

    NASA Astrophysics Data System (ADS)

    van T Erve, Olaf; Hanbicki, Aubrey; Li, Connie; Jonker, Berend

    Spin Hall effects in metals have been successfully measured using electrical methods such as nonlocal spin valve transport, ferromagnetic resonance or spin torque transfer experiments. These methods require complex processing techniques and measuring setups. Here we present room temperature measurements of the spin Hall effect in non-magnetic metals such as Pt and β-W using a standard bench top magneto-optic Kerr effect (MOKE) system. With this system, one can readily determine the angular dependence of the induced polarization on the bias current direction. When a bias current is applied, the spin Hall effect causes electrons of opposite spin to be scattered in opposite directions, resulting in a spin accumulation at the surface of the film. The MOKE signal tracks the applied square wave bias current with an amplitude and phase directly related to the spin Hall angle. Using this technique, we show that the spin-Hall angle of β-W is opposite in sign and significantly larger than that of Pt. In addition, we use this technique to detect spin diffusion from β-W into Al thin films, as well as spin diffusion from the topological surface states of Bi2Se3 into Al. We will also show direct modulation of the reflected light up to 100 kHz, using Bi doped Cu samples. This work was supported by internal programs at NRL.

  20. Mobile Spectroscopic Instrumentation in Archaeometry Research.

    PubMed

    Vandenabeele, Peter; Donais, Mary Kate

    2016-01-01

    Mobile instrumentation is of growing importance to archaeometry research. Equipment is utilized in the field or at museums, thus avoiding transportation or risk of damage to valuable artifacts. Many spectroscopic techniques are nondestructive and micro-destructive in nature, which preserves the cultural heritage objects themselves. This review includes over 160 references pertaining to the use of mobile spectroscopy for archaeometry. Following a discussion of terminology related to mobile instrumental methods, results of a literature survey on their applications for cultural heritage objects is presented. Sections devoted to specific techniques are then provided: Raman spectroscopy, X-ray fluorescence spectrometry, Fourier transform infrared spectroscopy, laser-induced breakdown spectroscopy, and less frequently used techniques. The review closes with a discussion of combined instrumental approaches.

  1. Spin Rotation of Formalism for Spin Tracking

    SciTech Connect

    Luccio,A.

    2008-02-01

    The problem of which coefficients are adequate to correctly represent the spin rotation in vector spin tracking for polarized proton and deuteron beams in synchrotrons is here re-examined in the light of recent discussions. The main aim of this note is to show where some previous erroneous results originated and how to code spin rotation in a tracking code. Some analysis of a recent experiment is presented that confirm the correctness of the assumptions.

  2. Spin canting in ferrite nanoparticles

    NASA Astrophysics Data System (ADS)

    Marx, J.; Huang, H.; Salih, K. S. M.; Thiel, W. R.; Schünemann, V.

    2016-12-01

    Recently, an easily scalable process for the production of small (3 -7 nm) monodisperse superparamagnetic ferrite nanoparticles MeFe2O4 (Me = Zn, Mn, Co) from iron metal and octanoic acid has been reported (Salih et al., Chem. Mater. 25 1430-1435 2013). Here we present a Mössbauer spectroscopic study of these ferrite nanoparticles in external magnetic fields of up to B = 5 T at liquid helium temperatures. Our analysis shows that all three systems show a comparable inversion degree and the cationic distribution for the tetrahedral A and the octahedral B sites has been determined to (Zn0.19Fe0.81) A [Zn0.81Fe1.19] B O4, (Mn0.15Fe0.85) A [Mn0.85Fe1.15] B O4 and (Co0.27Fe0.73) A [Co0.73Fe1.27] B O4. Spin canting occurs presumably in the B-sites and spin canting angles of 33°, 51° and 59° have been determined for the zinc, the manganese, and the cobalt ferrite nanoparticles.

  3. Advanced Magnetic Resonance Techniques for the Structural Characterization of Aminoxyl Radicals and Their Inorganic-Organic Nanocomposite Systems.

    PubMed

    Eckert, Hellmut

    2016-11-15

    Electron and nuclear spins are extremely sensitive probes of their local structural and dynamic surroundings. Their Zeeman energy levels are modified by different types of local magnetic and electric fields created by their structural environment, which influence their magnetic resonance condition. For this reason, electron spin resonance (ESR) and nuclear magnetic resonance (NMR) spectroscopies have become extremely powerful tools of structural analysis, which are being widely used for the structural characterization of complex solids. Following a brief introduction into the basic theoretical foundations the most commonly used techniques and their application towards the structural characterization of paramagnetic solids based on aminoxyl radicals and their inorganic-organic nanocomposites will be described. Both ESR and NMR observables are useful for monitoring intermolecular interactions between unpaired electron spins, which are particularly important for the design of organically based ferromagnetic systems. ESR and NMR methods based on this effect can be used for monitoring the synthesis of polynitroxides and for evaluating the catalytic function of aminoxyl intercalation compounds. Finally, the sensitivity of ESR signals to motional dynamics can be exploited for characterizing molecule-surface interactions in nanocomposite systems. In the context of the latter work recently developed signal enhancement strategies are described, using polarization transfer from electron spins to nuclear spins for NMR spectroscopic detection.

  4. Aharonov-Bohm physics with spin. II. Spin-flip effects in two-dimensional ballistic systems

    NASA Astrophysics Data System (ADS)

    Frustaglia, Diego; Hentschel, Martina; Richter, Klaus

    2004-04-01

    We study spin effects in the magnetoconductance of ballistic mesoscopic systems subject to inhomogeneous magnetic fields. We present a numerical approach to the spin-dependent Landauer conductance which generalizes recursive Green-function techniques to the case with spin. Based on this method we address spin-flip effects in quantum transport of spin-polarized and spin-unpolarized electrons through quantum wires and various two-dimensional Aharonov-Bohm geometries. In particular, we investigate the range of validity of a spin-switch mechanism recently found which allows for controlling spins indirectly via Aharonov-Bohm fluxes. Our numerical results are compared to a transfer-matrix model for one-dimensional ring structures presented in the first paper [Hentschel et al., Phys. Rev. B, preceding paper, Phys. Rev. B 69, 155326 (2004)] of this series.

  5. Paramagnetic Enhancement of Nuclear Spin-Spin Coupling.

    PubMed

    Cherry, Peter John; Rouf, Syed Awais; Vaara, Juha

    2017-03-14

    We present a derivation and computations of the paramagnetic enhancement of the nuclear magnetic resonance (NMR) spin-spin coupling, which may be expressed in terms of the hyperfine coupling (HFC) and (for systems with multiple unpaired electrons) zero-field splitting (ZFS) tensors. This enhancement is formally analogous to the hyperfine contributions to the NMR shielding tensor as formulated by Kurland and McGarvey. The significance of the spin-spin coupling enhancement is demonstrated by using a combination of density-functional theory and correlated ab initio calculations, to determine the HFC and ZFS tensors, respectively, for two paramagnetic 3d metallocenes, a Cr(II)(acac)2 complex, a Co(II) pyrazolylborate complex, and a lanthanide system, Gd-DOTA. Particular attention is paid to relativistic effects in HFC tensors, which are calculated using two methods: a nonrelativistic method supplemented by perturbational spin-orbit coupling corrections, and a fully relativistic, four-component matrix-Dirac-Kohn-Sham approach. The paramagnetic enhancement lacks a direct dependence on the distance between the coupled nuclei, and represents more the strength and orientation of the individual hyperfine couplings of the two nuclei to the spin density distribution. Therefore, the enhancement gains relative importance as compared to conventional coupling as the distance between the nuclei increases, or generally in the cases where the conventional coupling mechanisms result in a small value. With the development of the experimental techniques of paramagnetic NMR, the more significant enhancements, e.g., of the (13)C(13)C couplings in the Gd-DOTA complex (as large as 9.4 Hz), may eventually become important.

  6. Spectroscopic investigations of a novel tricyanofuran dye for nonlinear optics.

    PubMed

    Han, Likun; Jiang, Yadong; Li, Wei; Li, Yuanxun; Hao, Peng

    2008-11-01

    A novel tricyanofuran dye was synthesized and the dye-in-polymer films were fabricated by spin-coating process. The spectroscopic properties of the dye in the solutions and polymer films were investigated by the absorption spectra and fluorescence emission spectra. It is found that the absorption and fluorescence maxima are largely red-shifted along with the increase of the solvent polarity. And the low values of fluorescence quantum yield in higher polarity solvents suggest the presence of twisted intramolecular charge transfer states of the dye. Moreover, the second order polarizability value of the novel dye was estimated based on the quantum-mechanical two-level model.

  7. Spectroscopic study of the extremely fast rotating star 44 Geminorum

    NASA Astrophysics Data System (ADS)

    Iliev, L.; Vennes, S.; Kawka, A.; Kubat, J.; Nemeth, P.; Borisov, G.; KRaus, M.

    Stars with extremely fast rotation represent interesting challenge to modern understanding of the stellar evolution. The reasons why such a spin-up process should occur during the evolution to otherwise normal star are still not well understood. Already in the beginning of the XX century Otto Struve proposed that fast rotation of the group of stars spectroscopically classified as Be could be the main reason for the formation of observed disks of circumstellar material around them. This circumstellar material is responsible for the emission lines observed in the spectrum of Be-stars as well as for the whole complex of spectral and photometrical patterns called in general Be-phenomenon.

  8. Spin Seebeck power generators

    SciTech Connect

    Cahaya, Adam B.; Tretiakov, O. A.; Bauer, Gerrit E. W.

    2014-01-27

    We derive expressions for the efficiency and figure of merit of two spin caloritronic devices based on the spin Seebeck effect (SSE), i.e., the generation of spin currents by a temperature gradient. The inverse spin Hall effect is conventionally used to detect the SSE and offers advantages for large area applications. We also propose a device that converts spin current into electric one by means of a spin-valve detector, which scales favorably to small sizes and approaches a figure of merit of 0.5 at room temperature.

  9. Spin-Mechatronics

    NASA Astrophysics Data System (ADS)

    Matsuo, Mamoru; Saitoh, Eiji; Maekawa, Sadamichi

    2017-01-01

    We investigate the interconversion phenomena between spin and mechanical angular momentum in moving objects. In particular, the recent results on spin manipulation and spin-current generation by mechanical motion are examined. In accelerating systems, spin-dependent gauge fields emerge, which enable the conversion from mechanical angular momentum into spins. Such a spin-mechanical effect is predicted by quantum theory in a non-inertial frame. Experiments which confirm the effect, i.e., the resonance frequency shift in nuclear magnetic resonance, the stray field measurement of rotating metals, and electric voltage generation in liquid metals, are discussed.

  10. Forensic age estimation via 3-T magnetic resonance imaging of ossification of the proximal tibial and distal femoral epiphyses: Use of a T2-weighted fast spin-echo technique.

    PubMed

    Ekizoglu, Oguzhan; Hocaoglu, Elif; Inci, Ercan; Can, Ismail Ozgur; Aksoy, Sema; Kazimoglu, Cemal

    2016-03-01

    Radiation exposure during forensic age estimation is associated with ethical implications. It is important to prevent repetitive radiation exposure when conducting advanced ultrasonography (USG) and magnetic resonance imaging (MRI). The purpose of this study was to investigate the utility of 3.0-T MRI in determining the degree of ossification of the distal femoral and proximal tibial epiphyses in a group of Turkish population. We retrospectively evaluated coronal T2-weighted and turbo spin-echo sequences taken upon MRI of 503 patients (305 males, 198 females; age 10-30 years) using a five-stage method. Intra- and interobserver variations were very low. (Intraobserver reliability was κ=0.919 for the distal femoral epiphysis and κ=0.961 for the proximal tibial epiphysis, and interobserver reliability was κ=0.836 for the distal femoral epiphysis and κ=0.885 for the proximal tibial epiphysis.) Spearman's rank correlation analysis indicated a significant positive relationship between age and the extent of ossification of the distal femoral and proximal tibial epiphyses (p<0.001). Comparison of male and female data revealed significant between-gender differences in the ages at first attainment of stages 2, 3, and 4 ossifications of the distal femoral epiphysis and stage 1 and 4 ossifications of the proximal tibial epiphysis (p<0.05). The earliest ages at which ossification of stages 3, 4, and 5 was evident in the distal femoral epiphysis were 14, 17, and 22 years in males and 13, 16, and 21 years in females, respectively. Proximal tibial epiphysis of stages 3, 4, and 5 ossification was first noted at ages 14, 17, and 18 years in males and 13, 15, and 16 years in females, respectively. MRI of the distal femoral and proximal tibial epiphyses is an alternative, noninvasive, and reliable technique to estimate age.

  11. Optical Control of Donor Spin Qubits in Silicon

    PubMed Central

    Gullans, M. J.; Taylor, J. M.

    2016-01-01

    We show how to achieve optical, spin-selective transitions from the ground state to excited orbital states of group-V donors (P, As, Sb, Bi) in silicon. We consider two approaches based on either resonant, far-infrared (IR) transitions of the neutral donor or resonant, near-IR excitonic transitions. For far-IR light, we calculate the dipole matrix elements between the valley-orbit and spin-orbit split states for all the goup-V donors using effective mass theory. We then calculate the maximum rate and amount of electron-nuclear spin-polarization achievable through optical pumping with circularly polarized light. We find this approach is most promising for Bi donors due to their large spin-orbit and valley-orbit interactions. Using near-IR light, spin-selective excitation is possible for all the donors by driving a two-photon Λ-transition from the ground state to higher orbitals with even parity. We show that externally applied electric fields or strain allow similar, spin-selective Λ-transition to odd-parity excited states. We anticipate these results will be useful for future spectroscopic investigations of donors, quantum control and state preparation of donor spin qubits, and for developing a coherent interface between donor spin qubits and single photons. PMID:28127227

  12. Spectroscopic classification of supernova candidates

    NASA Astrophysics Data System (ADS)

    Hodgkin, S. T.; Hall, A.; Fraser, M.; Campbell, H.; Wyrzykowski, L.; Kostrzewa-Rutkowska, Z.; Pietro, N.

    2014-09-01

    We report the spectroscopic classification of four supernovae at the 2.5m Isaac Newton Telescope on La Palma, using the Intermediate Dispersion Spectrograph and the R300V grating (3500-8000 Ang; ~6 Ang resolution).

  13. Spectroscopic constants and potential energy curves of HfH

    NASA Astrophysics Data System (ADS)

    Balasubramanian, K.; Das, Kalyan K.

    1991-01-01

    Complete active space multiconfiguration self-consistent field (CAS-MCSFC) followed by full second-roder CI (SOCI) and relativistic configuration interaction (RCI) including spin-orbit coupling calculations are carried out on 14 λ- s and 10 ω-ω states of HfH. The spectroscopic constants ( re, Te, ωe, μe, De) of these states are computed. The potential energy curves of these states are also reported. We find several electronic transitions in the IR-UV regions for HfH which are yet to be observed. The ground state of HfH is found to be a {3}/{2} state (82% 2Δ, 8% 2Π) with r e = 1.854 Å, ωe = 1704 cm -1 and μe = 0.66 D. The spin-orbit effects are found to be very significant for HfH.

  14. Editorial commentary revisited and the spin move refined.

    PubMed

    Lubowitz, James H; Provencher, Matthew T; Brand, Jefferson C; Rossi, Michael J

    2015-04-01

    First, editorial commentary: editorial commentary may be educational and may be controversial, but above all else, authors come first. Second, The Spin Move: The Spin Move is effective, cost-effective, and ubiquitous because, while many techniques are specific to a single joint, The Spin Move can be performed as a part of any arthroscopic and related procedure. However, like many advanced procedures, The Spin Move, when poorly executed, entails substantial risk. Preoperative planning is essential, and The Spin Move must be reviewed by inexperienced practitioners, in detailed text, figures tables, and video, at www.arthroscopytechniques.org. Practice makes perfect.

  15. Propagation of nonlinearly generated harmonic spin waves in microscopic stripes

    SciTech Connect

    Rousseau, O.; Yamada, M.; Miura, K.; Ogawa, S.; Otani, Y.

    2014-02-07

    We report on the experimental study of the propagation of nonlinearly generated harmonic spin waves in microscopic CoFeB stripes. Using an all electrical technique with coplanar waveguides, we find that two kinds of spin waves can be generated by nonlinear frequency multiplication. One has a non-uniform spatial geometry and thus requires appropriate detector geometry to be identified. The other corresponds to the resonant fundamental propagative spin waves and can be efficiently excited by double- or triple-frequency harmonics with any geometry. Nonlinear excited spin waves are particularly efficient in providing an electrical signal arising from spin wave propagation.

  16. Spectroscopic Detection of Pathogens

    SciTech Connect

    ALAM,M. KATHLEEN; TIMLIN,JERILYN A.; MARTIN,LAURA E.; HJELLE,DRIAN; LYONS,RICK; GARRISON,KRISTIN

    2000-11-01

    The goal of this LDRD Research project was to provide a preliminary examination of the use of infrared spectroscopy as a tool to detect the changes in cell cultures upon activation by an infectious agent. Due to a late arrival of funding, only 5 months were available to transfer and setup equipment at UTTM,develop cell culture lines, test methods of in-situ activation and collect kinetic data from activated cells. Using attenuated total reflectance (ATR) as a sampling method, live cell cultures were examined prior to and after activation. Spectroscopic data were collected from cells immediately after activation in situ and, in many cases for five successive hours. Additional data were collected from cells activated within a test tube (pre-activated), in both transmission mode as well as in ATR mode. Changes in the infrared data were apparent in the transmission data collected from the pre-activated cells as well in some of the pre-activated ATR data. Changes in the in-situ activated spectral data were only occasionally present due to (1) the limited time cells were studied and (2) incomplete activation. Comparison of preliminary data to infrared bands reported in the literature suggests the primary changes seen are due an increase in ribonucleic acid (RNA) production. This work will be continued as part of a 3 year DARPA grant.

  17. Analysis of a new class of grazing incidence spectroscopic telescope

    NASA Technical Reports Server (NTRS)

    Green, J. C.; Bowyer, S.

    1986-01-01

    The throughput and imaging properties of one of a new class of grazing incidence spectroscopic telescope are examined with a Monte Carlo ray tracing technique. The results are compared with Wolter Schwarzschild type II telescopes of similar size. The image quality of this telescope is comparable, and the control of the off-axis light is superior to the Wolter Schwarzschild design.

  18. Spectroscopic probes of vibrationally excited molecules at chemically significant energies

    SciTech Connect

    Rizzo, T.R.

    1993-12-01

    This project involves the application of multiple-resonance spectroscopic techniques for investigating energy transfer and dissociation dynamics of highly vibrationally excited molecules. Two major goals of this work are: (1) to provide information on potential energy surfaces of combustion related molecules at chemically significant energies, and (2) to test theoretical modes of unimolecular dissociation rates critically via quantum-state resolved measurements.

  19. Ultraminiature one-shot Fourier-spectroscopic tomography

    NASA Astrophysics Data System (ADS)

    Sato, Shun; Qi, Wei; Kawashima, Natsumi; Nogo, Kosuke; Hosono, Satsuki; Nishiyama, Akira; Wada, Kenji; Ishimaru, Ichiro

    2016-02-01

    We propose one-shot Fourier-spectroscopic tomography as a method of ultraminiature spectroscopic imaging. The apparatus used in this technique consists solely of a glass slab with a portion of its surface polished at a certain inclination angle-a device we term a relative-inclination phase shifter-simply mounted on an infinite-distance-corrected optical imaging system. For this reason, the system may be ultraminiaturized to sizes on the order of a few tens of millimeters. Moreover, because our technique uses a near-common-path wavefront-division phase-shift interferometer and has absolutely no need for a mechanical drive unit, it is highly robust against mechanical vibrations. In addition, because the proposed technique uses Fourier-transform spectroscopy, it offers highly efficient light utilization and an outstanding signal-to-noise ratio compared to devices that incorporate distributed or hyperspectral acousto-optical tunable filters. The interferogram, which is a pattern formed by interference of waves at all wavelengths, reflects the spatial variation in the intensity of the interference depending on the magnitude of the phase shift. We first discuss the design of the phase shifter and the results of tests to validate the principles underlying one-shot Fourier-spectroscopic tomography. We then report the results of one-dimensional spectroscopic imaging using this technique.

  20. Tidal deformations of a spinning compact object

    NASA Astrophysics Data System (ADS)

    Pani, Paolo; Gualtieri, Leonardo; Maselli, Andrea; Ferrari, Valeria

    2015-07-01

    The deformability of a compact object induced by a perturbing tidal field is encoded in the tidal Love numbers, which depend sensibly on the object's internal structure. These numbers are known only for static, spherically-symmetric objects. As a first step to compute the tidal Love numbers of a spinning compact star, here we extend powerful perturbative techniques to compute the exterior geometry of a spinning object distorted by an axisymmetric tidal field to second order in the angular momentum. The spin of the object introduces couplings between electric and magnetic deformations and new classes of induced Love numbers emerge. For example, a spinning object immersed in a quadrupolar, electric tidal field can acquire some induced mass, spin, quadrupole, octupole and hexadecapole moments to second order in the spin. The deformations are encoded in a set of inhomogeneous differential equations which, remarkably, can be solved analytically in vacuum. We discuss certain subtleties in defining the tidal Love numbers in general relativity, which are due to the difficulty in separating the tidal field from the linear response of the object in the solution, even in the static case. By extending the standard procedure to identify the linear response in the static case, we prove analytically that the Love numbers of a Kerr black hole remain zero to second order in the spin. As a by-product, we provide the explicit form for a slowly-rotating, tidally-deformed Kerr black hole to quadratic order in the spin, and discuss its geodesic and geometrical properties.

  1. Application of imaging spectroscopic reflectometry for characterization of gold reduction from organometallic compound by means of plasma jet technology

    NASA Astrophysics Data System (ADS)

    Vodák, Jiří; Nečas, David; Pavliňák, David; Macak, Jan M.; Řičica, Tomáš; Jambor, Roman; Ohlídal, Miloslav

    2017-02-01

    This work presents a new application of imaging spectroscopic reflectometry to determine a distribution of metallic gold in a layer of an organogold precursor which was treated by a plasma jet. Gold layers were prepared by spin coating from a solution of the precursor containing a small amount of polyvinylpyrrolidone on a microscopy glass, then they were vacuum dried. A difference between reflectivity of metallic gold and the precursor was utilized by imaging spectroscopic reflectometry to create a map of metallic gold distribution using a newly developed model of the studied sample. The basic principle of the imaging spectroscopic reflectometry is also shown together with the data acquisition principles. XPS measurements and microscopy observations were made to complete the imaging spectroscopic reflectometry results. It is proved that the imaging spectroscopic reflectometry represents a new method for quantitative evaluation of local reduction of metallic components from metaloorganic compounds.

  2. Proton echo-planar spectroscopic imaging with highly effective outer volume suppression using combined presaturation and spatially selective echo dephasing.

    PubMed

    Chu, Archie; Alger, Jeffry R; Moore, Gregory J; Posse, Stefan

    2003-05-01

    A highly effective outer volume suppression (OVS) technique, termed spatially selective echo dephasing (SSED), which employs gradient dephasing of spatially selective spin echoes, is introduced. SSED, which is relatively insensitive to T(1) dispersion among lipid signals and B(1) inhomogeneity, was integrated with very high spatial resolution 2D proton echo-planar spectroscopic imaging (PEPSI) to assess residual lipid bleeding into cortical regions in the human brain. The method was optimized to minimize signal refocusing of secondary spin-echoes in areas of overlapping suppression slices. A comparison of spatial presaturation with single or double SSED, and with combined presaturation and SSED shows that the latter method has superior performance with spatially uniform lipid suppression factors in excess of 70. Metabolite mapping (choline, creatine, and NAA) with a 64 x 64 spatial matrix and 0.3 cm(3) voxels in close proximity to peripheral lipid regions was demonstrated at 1.5 T with a scan time of 32 min using the standard head coil.

  3. Current heating induced spin Seebeck effect

    SciTech Connect

    Schreier, Michael Roschewsky, Niklas; Dobler, Erich; Meyer, Sibylle; Huebl, Hans; Goennenwein, Sebastian T. B.; Gross, Rudolf

    2013-12-09

    A measurement technique for the spin Seebeck effect is presented, wherein the normal metal layer used for its detection is exploited simultaneously as a resistive heater and thermometer. We show how the various contributions to the measured total signal can be disentangled, allowing to extract the voltage signal solely caused by the spin Seebeck effect. To this end, we performed measurements as a function of the external magnetic field strength and its orientation. We find that the effect scales linearly with the induced rise in temperature, as expected for the spin Seebeck effect.

  4. On estimating the Venus spin vector

    NASA Technical Reports Server (NTRS)

    Argentiero, P. D.

    1972-01-01

    The improvement in spin vector and probe position estimates one may reasonably expect from the processing of such data is indicated. This was done by duplicating the ensemble calculations associated with a weighed least squares with a priori estimation technique applied to range rate data that were assumed to be unbiased and uncorrelated. The weighting matrix was assumed to be the inverse of the covariance matrix of the noise on the data. Attention is focused primarily on the spin vector estimation.

  5. Neutron spin evolution through broadband current sheet spin flippers

    NASA Astrophysics Data System (ADS)

    Stonaha, P.; Hendrie, J.; Lee, W. T.; Pynn, Roger

    2013-10-01

    Controlled manipulation of neutron spin is a critical tool for many neutron scattering techniques. We have constructed current-sheet, neutron spin flippers for use in Spin Echo Scattering Angle Measurement (SESAME) that comprise pairs of open-faced solenoids which introduce an abrupt field reversal at a shared boundary. The magnetic fields generated by the coils have been mapped and compared with both an analytical approximation and a numerical boundary integral calculation. The agreement is generally good, allowing the former method to be used for rapid calculations of the Larmor phase acquired by a neutron passing through the flipper. The evolution of the neutron spin through the current sheets inside the flipper is calculated for various geometries of the current-carrying conductors, including different wire shapes, arrangements, and common imperfections. The flipping efficiency is found to be sensitive to gaps between wires and between current sheets. SESAME requires flippers with high fields and flipping planes inclined to the neutron beam. To avoid substantial neutron depolarization, such flippers require an interdigitated arrangement of wires.

  6. Neutron spin evolution through broadband current sheet spin flippers.

    PubMed

    Stonaha, P; Hendrie, J; Lee, W T; Pynn, Roger

    2013-10-01

    Controlled manipulation of neutron spin is a critical tool for many neutron scattering techniques. We have constructed current-sheet, neutron spin flippers for use in Spin Echo Scattering Angle Measurement (SESAME) that comprise pairs of open-faced solenoids which introduce an abrupt field reversal at a shared boundary. The magnetic fields generated by the coils have been mapped and compared with both an analytical approximation and a numerical boundary integral calculation. The agreement is generally good, allowing the former method to be used for rapid calculations of the Larmor phase acquired by a neutron passing through the flipper. The evolution of the neutron spin through the current sheets inside the flipper is calculated for various geometries of the current-carrying conductors, including different wire shapes, arrangements, and common imperfections. The flipping efficiency is found to be sensitive to gaps between wires and between current sheets. SESAME requires flippers with high fields and flipping planes inclined to the neutron beam. To avoid substantial neutron depolarization, such flippers require an interdigitated arrangement of wires.

  7. Spinning eggs and ballerinas

    NASA Astrophysics Data System (ADS)

    Cross, Rod

    2013-01-01

    Measurements are presented on the rise of a spinning egg. It was found that the spin, the angular momentum and the kinetic energy all decrease as the egg rises, unlike the case of a ballerina who can increase her spin and kinetic energy by reducing her moment of inertia. The observed effects can be explained, in part, in terms of rolling friction between the egg and the surface on which it spins.

  8. Spectroscopic signatures of dressed Rydberg-Rydberg interactions in Sr

    NASA Astrophysics Data System (ADS)

    Mukherjee, Rick; Hazzard, Kaden

    2015-05-01

    Ultracold Rydberg-dressed atoms exhibit strong, long-range interactions that can potentially create exotic phases of matter and entangled states that are useful in quantum computation and metrology. Rydberg-dressed atoms are obtained by off-resonantly admixing a Rydberg state | R > into a long-lived electronic state, often the ground state. As a tool to observe dressed Rydberg interactions, we theoretically consider a spectroscopic method that relies on strontium's unique long-lived (~ 23 μ s) electronic excited state 3P1. Specifically, we consider an effective two level system: the electronic ground state | G > and the Rydberg dressed state | D > = | 3 P1 > + ɛ | R > with ɛ << 1 . Using spin language to describe this two level system, our proposed Ramsey scheme rotates the spins by angle θ, allows the atoms to interact for a time t, and then measures the final spin vector. Our calculation is exact and includes experimental complications, such as dissipation and pulse timing errors. Excitingly, the dependence of the spin vector on time and θ can be used to experimentally measure the strength and power law dependence of the dressed Rydberg atom interaction.

  9. High-spin band structure of 192Tl

    NASA Astrophysics Data System (ADS)

    Kreiner, A. J.; Filevich, A.; García Bermúdez, G.; Mariscotti, M. A. J.; Baktash, C.; der Mateosian, E.; Thieberger, P.

    1980-03-01

    High-spin states in 192Tl, excited through the 181Ta(18O,7n) and 181Ta(16O,5n) reactions, were studied using in-beam γ-ray spectroscopic techniques. Excitation functions, activity spectra, γ-ray angular distributions, and multidimensional coincidences were measured. The strongly Coríolis-distorted π~h92×ν~i132 two-quasiparticle band already known in the heavier 194,196,198Tl isotopes has also been found in this case based on an Iπ=8- isomeric state at 250.6 keV above the known long-lived 7+ level. Trends already noted in the other Tl isotopes and also predicted by two-quasiparticle plus-rotor model calculations are confirmed thus reinforcing such a theoretical description. NUCLEAR REACTIONS 181Ta(18O,xnγ), E=105-125 MeV; 181Ta(16O,xnγ), E=95-105 MeV; measured Eγ, Iγ, σ(E, Eγ, θγ), γ-γ coin.; 192Tl levels deduced, J, π, T12. Natural target. Ge(Li) detectors.

  10. Evaluating Human Breast Ductal Carcinomas with High-Resolution Magic-Angle Spinning Proton Magnetic Resonance Spectroscopy

    NASA Astrophysics Data System (ADS)

    Cheng, Leo Ling; Chang, I.-Wen; Smith, Barbara L.; Gonzalez, R. Gilberto

    1998-11-01

    We report the results of a study of human breast ductal carcinomas, conducted by using high resolution magic angle spinning proton magnetic resonance spectroscopy (HRMAS 1HMRS). This recently developed spectroscopic technique can measure tissue metabolism from intact pathological specimens and identify tissue biochemical changes, which closely correspond to tumorin vivostate. This procedure objectively indicates diagnostic parameters, independent of the skill and experience of the investigator, and has the potential to reduce the sampling errors inherently associated with procedures of conventional histopathology. In this study, we measured 19 cases of female ductal carcinomas. Our results demonstrate that: (1) highly resolved spectra of intact specimens of human breast ductal carcinomas can be obtained; (2) carcinoma-free tissues and carcinomas are distinguishable by alterations in the intensities and the spin-spin relaxation time T2 of cellular metabolites; and (3) tumor metabolic markers, such as phosphocholine, lactate, and lipids, may correlate with the histopathological grade determined from evaluation of the adjacent specimen. Our results suggest that biochemical markers thus measured may function as a valuable adjunct to histopathology to improve the accuracy of and reduce the time frame required for the diagnosis of human breast cancer.

  11. Spinning Eggs and Ballerinas

    ERIC Educational Resources Information Center

    Cross, Rod

    2013-01-01

    Measurements are presented on the rise of a spinning egg. It was found that the spin, the angular momentum and the kinetic energy all decrease as the egg rises, unlike the case of a ballerina who can increase her spin and kinetic energy by reducing her moment of inertia. The observed effects can be explained, in part, in terms of rolling friction…

  12. Wurtzite spin lasers

    NASA Astrophysics Data System (ADS)

    Faria Junior, Paulo E.; Xu, Gaofeng; Chen, Yang-Fang; Sipahi, Guilherme M.; Žutić, Igor

    2017-03-01

    Semiconductor lasers are strongly altered by adding spin-polarized carriers. Such spin lasers could overcome many limitations of their conventional (spin-unpolarized) counterparts. While the vast majority of experiments in spin lasers employed zinc-blende semiconductors, the room-temperature electrical manipulation was first demonstrated in wurtzite GaN-based lasers. However, the underlying theoretical description of wurtzite spin lasers is still missing. To address this situation, focusing on (In,Ga)N-based wurtzite quantum wells, we develop a theoretical framework in which the calculated microscopic spin-dependent gain is combined with a simple rate equation model. A small spin-orbit coupling in these wurtzites supports simultaneous spin polarizations of electrons and holes, providing unexplored opportunities to control spin lasers. For example, the gain asymmetry, as one of the key figures of merit related to spin amplification, can change the sign by simply increasing the carrier density. The lasing threshold reduction has a nonmonotonic dependence on electron-spin polarization, even for a nonvanishing hole spin polarization.

  13. Room temperature electrical spin injection into GaAs by an oxide spin injector

    PubMed Central

    Bhat, Shwetha G.; Kumar, P. S. Anil

    2014-01-01

    Spin injection, manipulation and detection are the integral parts of spintronics devices and have attracted tremendous attention in the last decade. It is necessary to judiciously choose the right combination of materials to have compatibility with the existing semiconductor technology. Conventional metallic magnets were the first choice for injecting spins into semiconductors in the past. So far there is no success in using a magnetic oxide material for spin injection, which is very important for the development of oxide based spintronics devices. Here we demonstrate the electrical spin injection from an oxide magnetic material Fe3O4, into GaAs with the help of tunnel barrier MgO at room temperature using 3-terminal Hanle measurement technique. A spin relaxation time τ ~ 0.9 ns for n-GaAs at 300 K is observed along with expected temperature dependence of τ. Spin injection using Fe3O4/MgO system is further established by injecting spins into p-GaAs and a τ of ~0.32 ns is obtained at 300 K. Enhancement of spin injection efficiency is seen with barrier thickness. In the field of spin injection and detection, our work using an oxide magnetic material establishes a good platform for the development of room temperature oxide based spintronics devices. PMID:24998440

  14. High resolution spin- and angle-resolved photoelectron spectroscopy for 3D spin vectorial analysis

    NASA Astrophysics Data System (ADS)

    Okuda, Taichi; Miyamoto, Koji; Kimura, Akio; Namatame, Hirofumi; Taniguchi, Masaki

    2013-03-01

    Spin- and angle-resolved photoelectron spectroscopy (SARPES) is the excellent tool which can directly observe the band structure of crystals with separating spin-up and -down states. Recent findings of new class of materials possessing strong spin orbit interaction such as Rashba spin splitting systems or topological insulators stimulate to develop new SARPES apparatuses and many sophisticated techniques have been reported recently. Here we report our newly developed a SARPES apparatus for spin vectorial analysis with high precision at Hiroshima Synchrotron Radiation Center. Highly efficient spin polarimeter utilizing very low energy electron diffraction (VLEED) makes high resolution (ΔE < 10 meV, Δθ ~ +/- 0.2 °) compatible with the SARPES measurement. By placing two VLEED spin detectors orthogonally we have realized the polarization measurement of all spin components (x, y and z) with the high resolution. Some examples of the three-dimensional spin observation will be presented. This work is supported by KAKENHI (23244066), Grant-in-Aid for Scientific Research (A) of Japan Society for the Promotion of Science.

  15. Laser spectroscopic measurement of helium isotope ratios.

    SciTech Connect

    Wang, L.-B.; Mueller, P.; Holt, R. J.; Lu, Z.-T.; O'Connor, T. P.; Sano, Y.; Sturchio, N.; Univ. of Illinois; Univ. of Tokyo; Univ. of Illinois at Chicago

    2003-06-13

    A sensitive laser spectroscopic method has been applied to the quantitative determination of the isotope ratio of helium at the level of {sup 3}He/{sup 4}He = 10{sup -7}--10{sup -5}. The resonant absorption of 1083 nm laser light by the metastable {sup 3}He atoms in a discharge cell was measured with the frequency modulation saturation spectroscopy technique while the abundance of {sup 4}He was measured by a direct absorption technique. The results on three different samples extracted from the atmosphere and commercial helium gas were in good agreement with values obtained with mass spectrometry. The achieved 3{sigma} detection limit of {sup 3}He in helium is 4 x 10{sup -9}. This demonstration required a 200 {mu}L STP sample of He. The sensitivity can be further improved, and the required sample size reduced, by several orders of magnitude with the addition of cavity enhanced spectroscopy.

  16. Experimental evidences of a large extrinsic spin Hall effect in AuW alloy

    SciTech Connect

    Laczkowski, P.; Rojas-Sánchez, J.-C.

    2014-04-07

    We report an experimental study of a gold-tungsten alloy (7 at. % W concentration in Au host) displaying remarkable properties for spintronics applications using both magneto-transport in lateral spin valve devices and spin-pumping with inverse spin Hall effect experiments. A very large spin Hall angle of about 10% is consistently found using both techniques with the reliable spin diffusion length of 2 nm estimated by the spin sink experiments in the lateral spin valves. With its chemical stability, high resistivity, and small induced damping, this AuW alloy may find applications in the nearest future.

  17. Spin transport and precession in graphene measured by nonlocal and three-terminal methods

    SciTech Connect

    Dankert, André Kamalakar, Mutta Venkata; Bergsten, Johan; Dash, Saroj P.

    2014-05-12

    We investigate the spin transport and precession in graphene by using the Hanle effect in nonlocal and three-terminal measurement geometries. Identical spin lifetimes, spin diffusion lengths, and spin polarizations are observed in graphene devices for both techniques over a wide range of temperatures. The magnitude of the spin signals is well explained by spin transport models. These observations rules out any signal enhancements or additional scattering mechanisms at the interfaces for both geometries. This validates the applicability of both the measurement methods for graphene based spintronics devices and their reliable extractions of spin parameters.

  18. The Steady Spin

    NASA Technical Reports Server (NTRS)

    Fuchs, Richard; Schmidt, Wilhelm

    1931-01-01

    With the object of further clarifying the problem of spinning, the equilibrium of the forces and moments acting on an airplane is discussed in light of the most recent test data. Convinced that in a spin the flight attitude by only small angles of yaw is more or less completely steady, the study is primarily devoted to an investigation of steady spin with no side slip. At small angles, wholly arbitrary and perfectly steady spins may be forced, depending on the type of control displacements. But at large angles only very steep and only "approaching steady" spins are possible, no matter what the control displacements.

  19. Spin supplementary conditions for spinning compact binaries

    NASA Astrophysics Data System (ADS)

    Mikóczi, Balázs

    2017-03-01

    We consider different spin supplementary conditions (SSC) for a spinning compact binary with the leading-order spin-orbit (SO) interaction. The Lagrangian of the binary system can be constructed, but it is acceleration-dependent in two cases of SSC. We rewrite the generalized Hamiltonian formalism proposed by Ostrogradsky and compute the conserved quantities and the dissipative part of relative motion during the gravitational radiation of each SSC. We give the orbital elements and observed quantities of the SO dynamics, for instance, the energy and the orbital angular momentum losses and waveforms, and discuss their SSC dependence.

  20. Inverse spin Hall effect by spin injection

    NASA Astrophysics Data System (ADS)

    Liu, S. Y.; Horing, Norman J. M.; Lei, X. L.

    2007-09-01

    Motivated by a recent experiment [S. O. Valenzuela and M. Tinkham, Nature (London) 442, 176 (2006)], the authors present a quantitative microscopic theory to investigate the inverse spin-Hall effect with spin injection into aluminum considering both intrinsic and extrinsic spin-orbit couplings using the orthogonalized-plane-wave method. Their theoretical results are in good agreement with the experimental data. It is also clear that the magnitude of the anomalous Hall resistivity is mainly due to contributions from extrinsic skew scattering.

  1. Electrically induced ambipolar spin vanishments in carbon nanotubes

    PubMed Central

    Matsumoto, D.; Yanagi, K.; Takenobu, T.; Okada, S.; Marumoto, K.

    2015-01-01

    Carbon nanotubes (CNTs) exhibit various excellent properties, such as ballistic transport. However, their electrically induced charge carriers and the relation between their spin states and the ballistic transport have not yet been microscopically investigated because of experimental difficulties. Here we show an electron spin resonance (ESR) study of semiconducting single-walled CNT thin films to investigate their spin states and electrically induced charge carriers using transistor structures under device operation. The field-induced ESR technique is suitable for microscopic investigation because it can directly observe spins in the CNTs. We observed a clear correlation between the ESR decrease and the current increase under high charge density conditions, which directly demonstrated electrically induced ambipolar spin vanishments in the CNTs. The result provides a first clear evidence of antimagnetic interactions between spins of electrically induced charge carriers and vacancies in the CNTs. The ambipolar spin vanishments would contribute the improvement of transport properties of CNTs because of greatly reduced carrier scatterings. PMID:26148487

  2. Spin Seebeck devices using local on-chip heating

    SciTech Connect

    Wu, Stephen M. Fradin, Frank Y.; Hoffman, Jason; Hoffmann, Axel; Bhattacharya, Anand

    2015-05-07

    A micro-patterned spin Seebeck device is fabricated using an on-chip heater. Current is driven through a Au heater layer electrically isolated from a bilayer consisting of Fe{sub 3}O{sub 4} (insulating ferrimagnet) and a spin detector layer. It is shown that through this method it is possible to measure the longitudinal spin Seebeck effect (SSE) for small area magnetic devices, equivalent to traditional macroscopic SSE experiments. Using a lock-in detection technique, it is possible to more sensitively characterize both the SSE and the anomalous Nernst effect (ANE), as well as the inverse spin Hall effect in various spin detector materials. By using the spin detector layer as a thermometer, we can obtain a value for the temperature gradient across the device. These results are well matched to values obtained through electromagnetic/thermal modeling of the device structure and with large area spin Seebeck measurements.

  3. Spectroscopic properties and potential energy surfaces of GeH

    NASA Astrophysics Data System (ADS)

    Balasubramanian, K.; Li, Junqing

    1988-04-01

    MCSCF (complete active space SCF) followed by configuration interaction calculations are carried out on 12 electronic states of GeH. Relativistic configuration interaction calculations are carried out with the objective of computing the spin-orbit corrections for the low-lying states. These calculations reveal the existence of 10 bound electronic states of GeH for which spectroscopic properties are computed. The three experimentally observed bands ( a- X, A- X, B- X) are assigned and the uncertainties in the experimental Te and ωe values of these states are corrected. In addition, the spectroscopic properties of 8 states are calculated which are yet to be observed. The spin-orbit coupling constant for the ground state X( 2Π) is calculated to be 869 cm -1. An accurate dissociation energy of 2.81 eV was obtained using {MCSCF}/{SOCI} calculation which employed a large Gaussian basis set questioning the experimental De of ˜3.3 eV obtained from the predissociation in the A2Δ state. It is shown that the intersection of the repulsive 4Π curve which dissociates into the ground state atoms causes predissociation in the A( 2Δ) , B( 2Σ +) , 2Σ +(III), and 2Π(II) states. The potential energy surfaces of a few excited states contain barriers. The calculated ground state dipole moment of 0.098 D is in disagreement with an experimental value of 1.24 D, questioning the experimental dipole moment.

  4. Using a non-invasive technique in nutrition: synchrotron radiation infrared microspectroscopy spectroscopic characterization of oil seeds treated with different processing conditions on molecular spectral factors influencing nutrient delivery.

    PubMed

    Zhang, Xuewei; Yu, Peiqiang

    2014-07-02

    Non-invasive techniques are a key to study nutrition and structure interaction. Fourier transform infrared microspectroscopy coupled with a synchrotron radiation source (SR-IMS) is a rapid, non-invasive, and non-destructive bioanalytical technique. To understand internal structure changes in relation to nutrient availability in oil seed processing is vital to find optimal processing conditions. The objective of this study was to use a synchrotron-based bioanalytical technique SR-IMS as a non-invasive and non-destructive tool to study the effects of heat-processing methods and oil seed canola type on modeled protein structure based on spectral data within intact tissue that were randomly selected and quantify the relationship between the modeled protein structure and protein nutrient supply to ruminants. The results showed that the moisture heat-related processing significantly changed (p<0.05) modeled protein structures compared to the raw canola (control) and those processing by dry heating. The moisture heating increased (p<0.05) spectral intensities of amide I, amide II, α-helices, and β-sheets but decreased (p<0.05) the ratio of modeled α-helices to β-sheet spectral intensity. There was no difference (p>0.05) in the protein spectral profile between the raw and dry-heated canola tissue and between yellow- and brown-type canola tissue. The results indicated that different heat processing methods have different impacts on the protein inherent structure. The protein intrinsic structure in canola seed tissue was more sensitive and more response to the moisture heating in comparison to the dry heating. These changes are expected to be related to the nutritive value. However, the current study is based on limited samples, and more large-scale studies are needed to confirm our findings.

  5. Multiple-quantum NMR studies of spin clusters in liquid crystals and zeolites

    SciTech Connect

    Pearson, J. . Dept. of Chemistry Lawrence Berkeley Lab., CA )

    1991-07-01

    This work will describe the use of MQ NMR to study spin clusters in anisotropic materials. A technique known as multiple-quantum spin counting was used to determine average spin cluster sizes liquid crystalline materials and in faujacitic zeolites containing aromatic hydrocarbons. The first half of the thesis will describe MQ NMR and the MQ spin counting technique, and the second half of the thesis will describe the actual experiments and their results.

  6. Resonant and Time-Resolved Spin Noise Spectroscopy

    NASA Astrophysics Data System (ADS)

    Song, Xinlin; Pursley, Brennan; Sih, Vanessa

    Spin noise spectroscopy is a technique which can probe the system while it remains in equilibrium. It was first demonstrated in atomic gases and then in solid state systems. Most existing spin noise measurement setups digitize the spin fluctuation signal and then analyze the power spectrum. Recently, pulsed lasers have been used to expand the bandwidth of accessible dynamics and allow direct time-domain correlation measurements. Here we develop and test a model for ultrafast pulsed laser spin noise measurements as well as a scheme to measure spin lifetimes longer than the laser repetition period. For the resonant spin noise technique, analog electronics are used to capture correlations from the extended pulse train, and the signal at a fixed time delay is measured as a function of applied magnetic field.

  7. Spin-transfer torque induced spin waves in antiferromagnetic insulators

    SciTech Connect

    Daniels, Matthew W.; Guo, Wei; Stocks, George Malcolm; Xiao, Di; Xiao, Jiang

    2015-01-01

    We explore the possibility of exciting spin waves in insulating antiferromagnetic films by injecting spin current at the surface. We analyze both magnetically compensated and uncompensated interfaces. We find that the spin current induced spin-transfer torque can excite spin waves in insulating antiferromagnetic materials and that the chirality of the excited spin wave is determined by the polarization of the injected spin current. Furthermore, the presence of magnetic surface anisotropy can greatly increase the accessibility of these excitations.

  8. Momentum and spin transport properties of spin polarized Fermi systems

    NASA Astrophysics Data System (ADS)

    Wei, Lijuan

    We carried out experiments on a spin polarized 3He- 4He mixture with 3He concentration x 3 = 6.26 x 10-4, and on pure 3He liquid. Spin polarization affects the transport properties of these Fermi systems. The effect on momentum transport was studied by using a vibrating-wire viscometer to measure viscosity of the 3He-4He mixture over the temperature range 6.09 mK--100 mK in 7.96 T and 1.00 T magnetic fields. A large viscosity increase was observed upon application of the 7.96 T magnetic field for temperature T < TF(TF = 19.5 mK is the Fermi temperature). The observed viscosity is in very good agreement with theoretical calculations for a dilute Fermi gas by Jeon and Mullin [1988, 1989] and Mullin and Jeon [1992]. The polarization effect on spin transport was investigated by measuring the transverse diffusion coefficient D ⊥ in pure 3He liquid at saturated vapor pressure and at 15.85 bar over the temperature range 4.5 mK--159 mK in a 7.96 T magnetic field. We used a pulsed NMR spin echo technique in a field gradient of 16.0 G/cm to do the measurements and fits to the Leggett equations [1970] to obtain D⊥. For T < 20 mK, we found D⊥ is less than measured in earlier experiments at lower magnetic fields. D⊥ does not increase with decreasing temperature as 1/T2, but appears to approach a constant as T → 0 while it is expected that the longitudinal spin diffusion coefficient D∥ ∝ 1/ T2. This is called spin diffusion anisotropy and it was observed for the first time in our 3He liquid experiments. The anisotropy temperature we determined for 3He liquid was Ta = 16.4 +/- 2.2 mK at saturated vapor pressure and in a 7.96 T magnetic field. The transverse spin diffusion in 3 He results agree qualitatively with theories proposed by Meyerovich and Musaeflan [1992, 1994]. They also agree qualitatively with theories proposed by Golosov and Ruckenstein [1995, 1998] by extrapolation of the dilute theory to a strongly interacting system.

  9. Enhancing forensic science with spectroscopic imaging

    NASA Astrophysics Data System (ADS)

    Ricci, Camilla; Kazarian, Sergei G.

    2006-09-01

    This presentation outlines the research we are developing in the area of Fourier Transform Infrared (FTIR) spectroscopic imaging with the focus on materials of forensic interest. FTIR spectroscopic imaging has recently emerged as a powerful tool for characterisation of heterogeneous materials. FTIR imaging relies on the ability of the military-developed infrared array detector to simultaneously measure spectra from thousands of different locations in a sample. Recently developed application of FTIR imaging using an ATR (Attenuated Total Reflection) mode has demonstrated the ability of this method to achieve spatial resolution beyond the diffraction limit of infrared light in air. Chemical visualisation with enhanced spatial resolution in micro-ATR mode broadens the range of materials studied with FTIR imaging with applications to pharmaceutical formulations or biological samples. Macro-ATR imaging has also been developed for chemical imaging analysis of large surface area samples and was applied to analyse the surface of human skin (e.g. finger), counterfeit tablets, textile materials (clothing), etc. This approach demonstrated the ability of this imaging method to detect trace materials attached to the surface of the skin. This may also prove as a valuable tool in detection of traces of explosives left or trapped on the surfaces of different materials. This FTIR imaging method is substantially superior to many of the other imaging methods due to inherent chemical specificity of infrared spectroscopy and fast acquisition times of this technique. Our preliminary data demonstrated that this methodology will provide the means to non-destructive detection method that could relate evidence to its source. This will be important in a wider crime prevention programme. In summary, intrinsic chemical specificity and enhanced visualising capability of FTIR spectroscopic imaging open a window of opportunities for counter-terrorism and crime-fighting, with applications ranging

  10. Pauli blocking in the low-lying, low-spin states of {sup 141}Pr

    SciTech Connect

    Scheck, M.; Choudry, S. N.; Elhami, E.; McEllistrem, M. T.; Mukhopadhyay, S.; Orce, J. N.; Yates, S. W.

    2008-09-15

    The low-lying, low-spin levels of {sup 141}Pr were investigated using (n,n{sup '}{gamma}) techniques. Level energies, branching ratios, and tentative spin assignments for more than 100 states, linked by nearly 300 transitions, were obtained from two angular distributions (E{sub n}=2.0 and 3.0 MeV) and an excitation function measurement (E{sub n}=1.5-3.2 MeV). The application of the Doppler-shift attenuation method led to the determination of lifetimes. The obtained spectroscopic data provide insight into the wave functions of the states observed. A detailed analysis of the [2{sub 1}{sup +} x d{sub 5/2}] and [2{sub 1}{sup +} x g{sub 7/2}] multiplets provides the first quantitative evidence for Pauli blocking in a spherical odd-mass nucleus. The unpaired particle is used to probe the microscopic structure of the first 2{sup +} state of the adjacent core nuclei {sup 140}Ce and {sup 142}Nd.

  11. Exploring the higher spin state structure of 31Si by γ-ray spectroscopy

    NASA Astrophysics Data System (ADS)

    Tai, Pei-Luan; Tabor, Samuel; Bender, Peter; Hamilton, L.; Tripathi, V.; Hoffman, C.; Clark, R. M.; Fallon, P.; Macchiavelli, A. O.; Paschalis, S.; Petri, M.; Carpenter, M. P.; Janssens, R. V. F.; Lauritsen, T.; Maccutchan, E. A.; Seweryniak, D.; Zhu, S.; Chiara, C.; Chen, X.; Reviol, W.; Sarantites, D. G.

    2016-09-01

    We present a comprehensive γ-ray spectroscopic study to the higher spin structure of 31Si. 31Si was produced through the 18O(18O, αn) reaction at the beam energy of 25 MeV at Argonne National Laboratory, which preferentially populates the higher spin states. The particle- γ- γ coincidence technique was used to build the energy level scheme. The Microball detector was used for selecting the reaction channel, and the multiple γ-ray coincidences were detected by GAMMASPHERE. The 31Si recoil energies and angles were kinematically reconstructed event-by-event, leading to a better Doppler correction and allowing us to discover 25 new states and 49 newly-observed γ transitions in total. 15 γ-decaying states above the neutron separation energy at 6587 keV were identified. PHY-07-56474, PHY-10-64819, DE-AC02-05CH-11231, DE-FG02-88ER-40406, DE-FG02-94ER-40834.

  12. Matrix model for strings beyond the c =1 barrier: The spin-s Heisenberg model on random surfaces

    NASA Astrophysics Data System (ADS)

    Ambjørn, J.; Khachatryan, Sh.; Sedrakyan, A.

    2015-07-01

    We consider a spin-s Heisenberg model coupled to two-dimensional quantum gravity. We quantize the model using the Feynman path integral, summing over all possible two-dimensional geometries and spin configurations. We regularize this path integral by starting with the R-matrices defining the spin-s Heisenberg model on a regular 2d Manhattan lattice. Two-dimensional quantum gravity is included by defining the R-matrices on random Manhattan lattices and summing over these, in the same way as one sums over 2d geometries using random triangulations in noncritical string theory. We formulate a random matrix model where the partition function reproduces the annealed average of the spin-s Heisenberg model over all random Manhattan lattices. A technique is presented which reduces the random matrix integration in the partition function to an integration over their eigenvalues.

  13. Optical Spin Noise of a Single Hole Spin Localized in an (InGa)As Quantum Dot

    NASA Astrophysics Data System (ADS)

    Dahbashi, Ramin; Hübner, Jens; Berski, Fabian; Pierz, Klaus; Oestreich, Michael

    2014-04-01

    We advance spin noise spectroscopy to the ultimate limit of single spin detection. This technique enables the measurement of the spin dynamic of a single heavy hole localized in a flat (InGa)As quantum dot. Magnetic field and light intensity dependent studies reveal even at low magnetic fields a strong magnetic field dependence of the longitudinal heavy hole spin relaxation time with an extremely long T1 of ≥180 μs at 31 mT and 5 K. The wavelength dependence of the spin noise power discloses for finite light intensities an inhomogeneous single quantum dot spin noise spectrum which is explained by charge fluctuations in the direct neighborhood of the quantum dot. The charge fluctuations are corroborated by the distinct intensity dependence of the effective spin relaxation rate.

  14. Spin blockade and coherent dynamics of high-spin states in a three-electron double quantum dot

    NASA Astrophysics Data System (ADS)

    Chen, Bao-Bao; Wang, Bao-Chuan; Cao, Gang; Li, Hai-Ou; Xiao, Ming; Guo, Guang-Can; Jiang, Hong-Wen; Hu, Xuedong; Guo, Guo-Ping

    2017-01-01

    Asymmetry in a three-electron double quantum dot (DQD) allows spin blockade, when spin-3/2 (quadruplet) states and spin-1/2 (doublet) states have different charge configurations. We have observed this DQD spin blockade near the (1,2)-(2,1) charge transition using a pulsed-gate technique and a charge sensor. We, then, use this spin blockade to detect Landau-Zener-Stückelberg interference and coherent oscillations between the spin quadruplet and doublet states. Such studies add to our understandings of coherence and control properties of three-spin states in a double dot, which, in turn, would benefit explorations into various qubit encoding schemes in semiconductor nanostructures.

  15. Spectroscopic issues in optical polarization of 3He gas for Magnetic Resonance Imaging of human lungs

    NASA Astrophysics Data System (ADS)

    Dohnalik, T.; Głowacz, B.; Olejniczak, Z.; Pałasz, T.; Suchanek, M.; Wojna, A.

    2013-10-01

    The Magnetic Resonance Imaging (MRI) of human lungs for diagnostic purposes became possible by using nuclear spin hyperpolarized noble gases, such as 3He. One of the methods to polarize 3He is the Metastability Exchange Optical Pumping (MEOP), which up to now has been performed at low pressure of about 1 mbar and in low magnetic field below 0.1 T (standard conditions). The equilibrium nuclear polarization can reach up to 80%, but it is dramatically reduced during the subsequent gas compression to the atmospheric pressure that is necessary for the lungs examination. Further polarization losses occur during the transportation of the gas to the hospital scanner. It was shown recently that up to 50% polarization can be obtained at elevated pressure exceeding 20 mbar, by using magnetic field higher than 0.1 T (nonstandard conditions). Therefore, following the construction of the low-field MEOP polarizer located in the lab, a dedicated portable unit was developed, which uses the magnetic field of the 1.5 T MR medical scanner and works in the continuous-flow regime. The first in Poland MRI images of human lungs in vivo were obtained on the upgraded to 3He resonance frequency Siemens Sonata medical scanner. An evident improvement in the image quality was achieved when using the new technique. The paper shows how spectroscopic measurements of 3He carried out in various experimental conditions led both to useful practical results and to significant progress in understanding fundamental processes taking place during MEOP.

  16. Slow spin relaxation in dipolar spin ice.

    NASA Astrophysics Data System (ADS)

    Orendac, Martin; Sedlakova, Lucia; Orendacova, Alzbeta; Vrabel, Peter; Feher, Alexander; Pajerowski, Daniel M.; Cohen, Justin D.; Meisel, Mark W.; Shirai, Masae; Bramwell, Steven T.

    2009-03-01

    Spin relaxation in dipolar spin ice Dy2Ti2O7 and Ho2Ti2O7 was investigated using the magnetocaloric effect and susceptibility. The magnetocaloric behavior of Dy2Ti2O7 at temperatures where the orientation of spins is governed by ``ice rules`` (T < Tice) revealed thermally activated relaxation; however, the resulting temperature dependence of the relaxation time is more complicated than anticipated by a mere extrapolation of the corresponding high temperature data [1]. A susceptibility study of Ho2Ti2O7 was performed at T > Tice and in high magnetic fields, and the results suggest a slow relaxation of spins analogous to the behavior reported in a highly polarized cooperative paramagnet [2]. [1] J. Snyder et al., Phys. Rev. Lett. 91 (2003) 107201. [2] B. G. Ueland et al., Phys. Rev. Lett. 96 (2006) 027216.

  17. Nanoscale imaging of paramagnetic spin labels using a single spin in diamond

    NASA Astrophysics Data System (ADS)

    Ariyaratne, Amila; Myers, Bryan; Pelliccione, Matthew; Jayich, Ania

    Spin-labeling molecules with paramagnetic species is a powerful technique for probing molecular structure. However, current techniques are ensemble measurements, inherently lacking the sensitivity to detect a single spin or the conformational properties of a single biomolecule. In this talk, we demonstrate an imaging technique that has the promise of single-spin imaging and ultimately molecular structure imaging. We present two-dimensional nanoscale imaging of a monolayer of gadolinium (Gd) atomic spin labels at ambient conditions. The sensing element is a single nitrogen-vacancy (NV) center in diamond. A patterned monolayer of Gd atoms self-assembled on a Si atomic force microscopy tip is controllably interacted with and detected by the NV center. The fluctuating magnetic field generated by GHz-scale Gd spin flips relaxes the NV center in a manner that depends strongly on the Gd-NV separation. Using this technique, we demonstrate a Gd-induced reduction of the T1 relaxation time of the NV center with nm spatial resolution. Our results indicate that nanometer-scale imaging of individual electronic spins at ambient conditions is within reach. This will ultimately enable the study of structural and functional studies of single biomolecules in their native, folded state.

  18. Spectroscopic Studies of Melanin.

    DTIC Science & Technology

    1986-01-01

    il), and leading to the production of oxygen radicals (12). Gallas (13) and Kozikowski et al. (14) have studied melanin fluorescence. As part of a...Raman scattering unobservable in aqueous solution by continuous wave techniques. As was also observed by Kozikowski et al. (14), the intrinsic...168B. 14. Kozikowski SD, Wolfram LJ, Alfano RR. Fluorescence spectroscopy of eumelanins. IEEE J Quant Electron 1984;OE20:1379-1382. 15. Slawinski J

  19. Spin Quantum Bit with Ferromagnetic Contacts for Circuit QED

    SciTech Connect

    Cottet, Audrey; Kontos, Takis

    2010-10-15

    We theoretically propose a scheme for a spin quantum bit based on a double quantum dot contacted to ferromagnetic elements. Interface exchange effects enable an all electric manipulation of the spin and a switchable strong coupling to a superconducting coplanar waveguide cavity. Our setup does not rely on any specific band structure and can in principle be realized with many different types of nanoconductors. This allows us to envision on-chip single spin manipulation and readout using cavity QED techniques.

  20. Spin quantum bit with ferromagnetic contacts for circuit QED.

    PubMed

    Cottet, Audrey; Kontos, Takis

    2010-10-15

    We theoretically propose a scheme for a spin quantum bit based on a double quantum dot contacted to ferromagnetic elements. Interface exchange effects enable an all electric manipulation of the spin and a switchable strong coupling to a superconducting coplanar waveguide cavity. Our setup does not rely on any specific band structure and can in principle be realized with many different types of nanoconductors. This allows us to envision on-chip single spin manipulation and readout using cavity QED techniques.

  1. Amorphous drug-PVP dispersions: application of theoretical, thermal and spectroscopic analytical techniques to the study of a molecule with intermolecular bonds in both the crystalline and pure amorphous state.

    PubMed

    Tobyn, Michael; Brown, Jonathan; Dennis, Andrew B; Fakes, Michael; Gao, Qi; Gamble, John; Khimyak, Yaroslav Z; McGeorge, Gary; Patel, Chhaya; Sinclair, Wayne; Timmins, Peter; Yin, Shawn

    2009-09-01

    We report the case of BMS-488043-PVP solid dispersions which when analysed using modulated DSC showed compliance with the Gordon-Taylor model, confirming ideal mixing behaviour of the two components. The nature or presence of stabilising interactions between drug and PVP could not be confirmed using this technique. Use of FT-IR, Raman and solid-state NMR spectroscopy confirmed the presence of stabilising hydrogen bond interactions between the drug and PVP. Similar interactions are present as intermolecular bonds in the crystalline and pure amorphous drug system. The Gordon-Taylor equation, as it is not predictive of the presence of intermolecular bonds such as hydrogen bonding in an amorphous dispersion, may underestimate the likely physical stability of solid dispersions which are produced and stabilised by these interactions.

  2. Transverse spin diffusion and spin rotation in very dilute, spin-polarized 3-4He mixtures

    NASA Astrophysics Data System (ADS)

    Candela, D.; McAllaster, D. R.; Wei, L.-J.

    1991-10-01

    We report measurements of the transverse-spin-diffusion coefficient D⊥ and the spin-rotation parameter Ωτ⊥ for two very dilute 3-4He mixtures (x3=1.82×10-3 and 6.26×10-4) spin polarized by an 8-T magnetic field. Brute-force spin polarization up to 40% was achieved at the lowest temperature, 6 mK. We find that Ωτ⊥ increases monotonically as the temperature is reduced through the Fermi temperature TF, in disagreement with the only previous experiment but in good agreement with recent theory. Unlike the earlier experiment, which measured spin echoes, the present experiments employed a spin-wave technique that avoids nonlinear excitation of the spin field. We compare our results with the recent calculations of Jeon and Mullin for spin transport in dilute gases with arbitrary polarization and degeneracy. The best fit to the data is obtained by scaling the quasiparticle interaction V(q) proposed by Ebner by a modest factor, 1.07. The corresponding s-wave scattering length is a=-1.21 Å. Good agreement is found for Ωτ⊥(T) at both concentrations and all temperatures, and for D⊥/Ωτ⊥(T) apart from the lower concentration at T<20 mK. The discrepancy in D⊥/Ωτ⊥ at the lowest temperatures and x3 could be explained by an unanticipated polarization dependence or by modification of the spin-wave boundary condition by processes occurring at the interface between the mixture and the silica cavity wall.

  3. Optical detection of spin Hall effect in metals

    NASA Astrophysics Data System (ADS)

    van T Erve, Olaf; Hanbicki, Aubrey; McCreary, Kathy; Li, Connie; Jonker, Berry

    2015-03-01

    Here we present room temperature measurements of the spin Hall effect in non-magnetic metals such as Pt and β-W using a standard bench top magneto-optic Kerr effect (MOKE) system. With this system, one can readily determine the angular dependence of the induced polarization on the bias current direction, the orientation of the spin Hall induced polarization, and the sign of the spin Hall angle. When a bias current is applied, the spin Hall effect causes electrons of opposite spin to be scattered in orthogonal directions, resulting in a spin accumulation at the surface of the film. The MOKE signal tracks the applied square wave bias current with an amplitude and phase directly related to the spin Hall angle. Using this technique, we show that the spin-Hall angle of β-W is opposite in sign and significantly larger than that of Pt, and follow the structural phase transition from β-W to α-W as the film is annealed through the dependence of the spin Hall angle on crystal structure. We also use this technique to detect spin diffusion from β-W into Al thin films. This work was supported by internal programs at NRL and the NRL Nanoscience Institute

  4. Integral dependent spin couplings in CI calculations

    NASA Technical Reports Server (NTRS)

    Iberle, K.; Davidson, E. R.

    1982-01-01

    Although the number of ways to combine Slater determinants to form spin eigenfunctions increases rapidly with the number of open shells, most of these spin couplings will make only a small contribution to a given state, provided the spin coupling is chosen judiciously. The technique of limiting calculations to the interacting subspace pioneered by Bunge (1970) was employed by Munch and Davidson (1975) to the vanadium atom. The use of an interacting space looses its advantage in more complex cases. However, the problem can always be reduced to only one interacting spin coupling by making the coefficients integral dependent. The present investigation is concerned with the performance of integral dependent interacting couplings, taking into account the results of three test calculations.

  5. Transverse Spin Relaxation in Liquid X

    SciTech Connect

    Romalis, M. V.; Ledbetter, M. P.

    2001-08-06

    Using spin-echo NMR techniques we study the transverse spin relaxation of hyperpolarized liquid X{sup 129}e in a spherical cell. We observe an instability of the transverse magnetization due to dipolar fields produced by liquid X{sup 129}e , and find that imperfections in the {pi} pulses of the spin-echo sequence suppress this instability. A simple perturbative model of this effect is in good agreement with the data. We obtain a transverse spin relaxation time of 1300sec in liquid X{sup 129}e , and discuss applications of hyperpolarized liquid X{sup 129}e as a sensitive magnetic gradiometer and for a permanent electric dipole moment search.

  6. A DVD Spectroscope: A Simple, High-Resolution Classroom Spectroscope

    ERIC Educational Resources Information Center

    Wakabayashi, Fumitaka; Hamada, Kiyohito

    2006-01-01

    Digital versatile disks (DVDs) have successfully made up an inexpensive but high-resolution spectroscope suitable for classroom experiments that can easily be made with common material and gives clear and fine spectra of various light sources and colored material. The observed spectra can be photographed with a digital camera, and such images can…

  7. Designer spin systems via inverse statistical mechanics

    NASA Astrophysics Data System (ADS)

    DiStasio, Robert A., Jr.; Marcotte, Étienne; Car, Roberto; Stillinger, Frank H.; Torquato, Salvatore

    2013-10-01

    nature of the target radial spin-spin correlation function. In the future, it will be interesting to explore whether such inverse statistical-mechanical techniques could be employed to design materials with desired spin properties.

  8. Microscopic understanding of spin current probed by shot noise

    NASA Astrophysics Data System (ADS)

    Arakawa, Tomonori

    The spin currents is one of key issue in the spintronics field and the generation and detection of those have been intensively studied by using various materials. The analysis of experiments, however, relies on phenomenological parameters such as spin relaxation length and spin flip time. The microscopic nature of the spin current such as energy distribution and energy relaxation mechanism, has not yet well understood. To establish a better microscopic understanding of spin currents, I focused on the shot noise measurement which is well established technique in the field of mesoscopic physics [Y. M. Blanter and M. B üttiker, Phys. Rep. 336, 1 (2000).]. Although there are many theoretically works about shot noise in the presence of spin currents, for example detection of spin accumulation [J. Meair, P. Stano, and P. Jacquod, Phys. Rev. B 84 (2011).], estimation of spin flip currents, and so on, these predictions have never been experimentally confirmed. In this context, we reported the first experimental detention of shot noise in the presence of the spin accumulation in a (Ga,Mn)As/tunnel barrier/n-GaAs based lateral spin valve device [T. Arakawa et al., Phys. Rev. Lett. 114, 016601 (2015).]. Together with this result, we found however that the effective temperature of the spin current drastically increases due to the spin injection process. This heating of electron system could be a big problem to realize future spin current devices by using quantum coherence, because the effective temperature rise directly related to the destruction of the coherence of the spin current. Therefore, then we focused on the mechanism of this heating and the energy relaxation in a diffusive channel. By measuring current noise and the DC offset voltage in the usual non-local spin valve signal as a function of the spin diffusion channel length, we clarified that the electron-electron interaction length, which is the characteristic length for the relaxation of the electron system, is

  9. Spectroscopic investigations of carious tooth decay.

    PubMed

    Thareja, R K; Sharma, A K; Shukla, Shobha

    2008-11-01

    We report on the elemental composition of healthy and infected part of human tooth using laser induced breakdown spectroscopy (LIBS). We have used prominent constituent transitions in laser-excited tooth to diagnose the state of the tooth. A nanosecond laser pulse (355nm, 5ns) was used as an ablating pulse and the sodium (3s2S-3p2P) at 588.99 and (3s2S-3p2P) at 589.99nm, strontium (5s21S-1s5P) at 460.55nm, and calcium (3d3D-4f 3F0) at 452.55nm transitions for spectroscopic analysis. The spectroscopic observations in conjunction with discriminate analysis showed that calcium attached to the hydroxyapatite structure of the tooth was affected severely at the infected part of the tooth. The position-time plots generated from two-dimensional (2D) images conclusively showed a decrease in calcium concentration in the infected region of the irradiated tooth. Using the technique, we could distinguish between the healthy and carious parts of the tooth with significant accuracy.

  10. Spin evolution in a radio frequency field studied through muon spin resonance.

    PubMed

    Clayden, Nigel J; Cottrell, Stephen P; McKenzie, Iain

    2012-01-01

    The application of composite inversion pulses to a novel area of magnetic resonance, namely muon spin resonance, is demonstrated. Results confirm that efficient spin inversion can readily be achieved using this technique, despite the challenging experimental setup required for beamline measurements and the short lifetime (≈2.2μs) associated with the positive muon probe. Intriguingly, because the muon spin polarisation is detected by positron emission, the muon magnetisation can be monitored during the radio-frequency (RF) pulse to provide a unique insight into the effect of the RF field on the spin polarisation. This technique is used to explore the application of RF inversion sequences under the non-ideal conditions typically encountered when setting up pulsed muon resonance experiments.

  11. Decoherence of a single spin coupled to an interacting spin bath

    NASA Astrophysics Data System (ADS)

    Wu, Ning; Fröhling, Nina; Xing, Xi; Hackmann, Johannes; Nanduri, Arun; Anders, Frithjof B.; Rabitz, Herschel

    2016-01-01

    Decoherence of a central spin coupled to an interacting spin bath via inhomogeneous Heisenberg coupling is studied by two different approaches, namely an exact equations of motion (EOMs) method and a Chebyshev expansion technique (CET). By assuming a wheel topology of the bath spins with uniform nearest-neighbor X X -type intrabath coupling, we examine the central spin dynamics with the bath prepared in two different types of bath initial conditions. For fully polarized baths in strong magnetic fields, the polarization dynamics of the central spin exhibits a collapse-revival behavior in the intermediate-time regime. Under an antiferromagnetic bath initial condition, the two methods give excellently consistent central spin decoherence dynamics for finite-size baths of N ≤14 bath spins. The decoherence factor is found to drop off abruptly on a short time scale and approach a finite plateau value which depends on the intrabath coupling strength nonmonotonically. In the ultrastrong intrabath coupling regime, the plateau values show an oscillatory behavior depending on whether N /2 is even or odd. The observed results are interpreted qualitatively within the framework of the EOM and perturbation analysis. The effects of anisotropic spin-bath coupling and inhomogeneous intrabath bath couplings are briefly discussed. Possible experimental realization of the model in a modified quantum corral setup is suggested.

  12. sick: The Spectroscopic Inference Crank

    NASA Astrophysics Data System (ADS)

    Casey, Andrew R.

    2016-03-01

    There exists an inordinate amount of spectral data in both public and private astronomical archives that remain severely under-utilized. The lack of reliable open-source tools for analyzing large volumes of spectra contributes to this situation, which is poised to worsen as large surveys successively release orders of magnitude more spectra. In this article I introduce sick, the spectroscopic inference crank, a flexible and fast Bayesian tool for inferring astrophysical parameters from spectra. sick is agnostic to the wavelength coverage, resolving power, or general data format, allowing any user to easily construct a generative model for their data, regardless of its source. sick can be used to provide a nearest-neighbor estimate of model parameters, a numerically optimized point estimate, or full Markov Chain Monte Carlo sampling of the posterior probability distributions. This generality empowers any astronomer to capitalize on the plethora of published synthetic and observed spectra, and make precise inferences for a host of astrophysical (and nuisance) quantities. Model intensities can be reliably approximated from existing grids of synthetic or observed spectra using linear multi-dimensional interpolation, or a Cannon-based model. Additional phenomena that transform the data (e.g., redshift, rotational broadening, continuum, spectral resolution) are incorporated as free parameters and can be marginalized away. Outlier pixels (e.g., cosmic rays or poorly modeled regimes) can be treated with a Gaussian mixture model, and a noise model is included to account for systematically underestimated variance. Combining these phenomena into a scalar-justified, quantitative model permits precise inferences with credible uncertainties on noisy data. I describe the common model features, the implementation details, and the default behavior, which is balanced to be suitable for most astronomical applications. Using a forward model on low-resolution, high signal

  13. Spin Hall effects

    NASA Astrophysics Data System (ADS)

    Sinova, Jairo; Valenzuela, Sergio O.; Wunderlich, J.; Back, C. H.; Jungwirth, T.

    2015-10-01

    Spin Hall effects are a collection of relativistic spin-orbit coupling phenomena in which electrical currents can generate transverse spin currents and vice versa. Despite being observed only a decade ago, these effects are already ubiquitous within spintronics, as standard spin-current generators and detectors. Here the theoretical and experimental results that have established this subfield of spintronics are reviewed. The focus is on the results that have converged to give us the current understanding of the phenomena, which has evolved from a qualitative to a more quantitative measurement of spin currents and their associated spin accumulation. Within the experimental framework, optical-, transport-, and magnetization-dynamics-based measurements are reviewed and linked to both phenomenological and microscopic theories of the effect. Within the theoretical framework, the basic mechanisms in both the extrinsic and intrinsic regimes are reviewed, which are linked to the mechanisms present in their closely related phenomenon in ferromagnets, the anomalous Hall effect. Also reviewed is the connection to the phenomenological treatment based on spin-diffusion equations applicable to certain regimes, as well as the spin-pumping theory of spin generation used in many measurements of the spin Hall angle. A further connection to the spin-current-generating spin Hall effect to the inverse spin galvanic effect is given, in which an electrical current induces a nonequilibrium spin polarization. This effect often accompanies the spin Hall effect since they share common microscopic origins. Both can exhibit the same symmetries when present in structures comprising ferromagnetic and nonmagnetic layers through their induced current-driven spin torques or induced voltages. Although a short chronological overview of the evolution of the spin Hall effect field and the resolution of some early controversies is given, the main body of this review is structured from a pedagogical

  14. Methanol Partial Oxidation on MoO3/SiO2 Catalysts: Application of Vibrational Spectroscopic Imaging Techniques in a High Throughput Operando Reactor

    SciTech Connect

    Li, Guosheng; Hu, Dehong; Xia, Guanguang; Zhang, Z Conrad

    2009-06-09

    A novel prototype high throughput operando (OHT) reactor designed and built for catalyst screening and characterization is presented in this article. For the first time, this OHT reactor integrates Fourier Transformation infrared (FT-IR) imaging technique and Raman spectroscopy in operando conditions. Using a focal plane array (HgCdTe FPA, 128x128 pixels, and 1,675 Hz frame rate) detector for the FT-IR imaging system, we are able to simultaneously follow the catalyst activity and selectivity of all parallel reaction channels. Each set of image data has 16, 384 IR spectra with a spectral range of 900-4000 cm-1 in an 8 cm-1 resolution. It only takes 2-20 second, depending on signal to noise ratio, to collect a full image of all reaction channels. Results on reactant conversion and product selectivity are obtained from FT-IR spectral analysis. Six home-designed Raman probes, one for each reaction channel, are used for simultaneous collection of Raman spectra of all catalysts and possible reaction intermediates on the catalyst surface under real reaction environment. As a model system, methanol partial oxidation reaction on silica supported molybdenum oxide (MoO3/SiO2) catalysts under different reaction conditions has been studied to show the performance of the OHT reactor.

  15. Spin caloritronics in graphene

    SciTech Connect

    Ghosh, Angsula; Frota, H. O.

    2015-06-14

    Spin caloritronics, the combination of spintronics with thermoelectrics, exploiting both the intrinsic spin of the electron and its associated magnetic moment in addition to its fundamental electronic charge and temperature, is an emerging technology mainly in the development of low-power-consumption technology. In this work, we study the thermoelectric properties of a Rashba dot attached to two single layer/bilayer graphene sheets as leads. The temperature difference on the two graphene leads induces a spin current, which depends on the temperature and chemical potential. We demonstrate that the Rashba dot behaves as a spin filter for selected values of the chemical potential and is able to filter electrons by their spin orientation. The spin thermopower has also been studied where the effects of the chemical potential, temperature, and also the Rashba term have been observed.

  16. Single-spin stochastic optical reconstruction microscopy

    PubMed Central

    Pfender, Matthias; Aslam, Nabeel; Waldherr, Gerald; Neumann, Philipp; Wrachtrup, Jörg

    2014-01-01

    We experimentally demonstrate precision addressing of single-quantum emitters by combined optical microscopy and spin resonance techniques. To this end, we use nitrogen vacancy (NV) color centers in diamond confined within a few ten nanometers as individually resolvable quantum systems. By developing a stochastic optical reconstruction microscopy (STORM) technique for NV centers, we are able to simultaneously perform sub–diffraction-limit imaging and optically detected spin resonance (ODMR) measurements on NV spins. This allows the assignment of spin resonance spectra to individual NV center locations with nanometer-scale resolution and thus further improves spatial discrimination. For example, we resolved formerly indistinguishable emitters by their spectra. Furthermore, ODMR spectra contain metrology information allowing for sub–diffraction-limit sensing of, for instance, magnetic or electric fields with inherently parallel data acquisition. As an example, we have detected nuclear spins with nanometer-scale precision. Finally, we give prospects of how this technique can evolve into a fully parallel quantum sensor for nanometer resolution imaging of delocalized quantum correlations. PMID:25267655

  17. Green's function study of a mixed spin-1 and spin-3/2 Heisenberg ferrimagnetic system

    NASA Astrophysics Data System (ADS)

    Mert, Gülistan

    2012-09-01

    The magnetic properties of a mixed spin-1 and spin-3/2 Heisenberg ferrimagnetic system on a square lattice are investigated by using the double-time temperature-dependent Green's function technique. In order to decouple the higher order Green's functions, Anderson and Callen's decoupling and random phase approximations have been used. The nearest- and next-nearest-neighbor interactions and the single-ion anisotropies are considered and their effects on compensation and critical temperature are studied.

  18. Starfish: Robust spectroscopic inference tools

    NASA Astrophysics Data System (ADS)

    Czekala, Ian; Andrews, Sean M.; Mandel, Kaisey S.; Hogg, David W.; Green, Gregory M.

    2015-05-01

    Starfish is a set of tools used for spectroscopic inference. It robustly determines stellar parameters using high resolution spectral models and uses Markov Chain Monte Carlo (MCMC) to explore the full posterior probability distribution of the stellar parameters. Additional potential applications include other types of spectra, such as unresolved stellar clusters or supernovae spectra.

  19. Picosecond Spin Caloritronics

    NASA Astrophysics Data System (ADS)

    Cahill, David G.

    The coupling of spin and heat, i.e., spin caloritronics, gives rise to new physical phenomena in nanoscale spin devices and new ways to manipulate local magnetization. Our work in this field takes advantage of recent advances in the measurement and understanding of heat transport at the nanoscale using ultrafast lasers. We use a picosecond duration pump laser pulses as a source of heat and picosecond duration probe laser pulses to detect changes in temperature, spin accumulation, and spin transfer torque using a combination of time-domain thermoreflectance and time-resolved magneto-optic Kerr effect Our pump-probe optical methods enable us to change the temperature of ferromagnetic layers on a picosecond time-scale and generate enormous heat fluxes on the order of 100 GW m-2 that persist for ~ 30 ps. Thermally-driven ultrafast demagnetization of a perpendicular ferromagnet leads to spin accumulation in a normal metal and spin transfer torque in an in-plane ferromagnet. The data are well described by models of spin generation and transport based on differences and gradients of thermodynamic parameters. The spin-dependent Seebeck effect of a perpendicular ferromagnetic layer converts a heat current into spin current, which in turn can be used to exert a spin transfer torque (STT) on a second ferromagnetic layer with in-plane magnetization. Using a [Co,Ni] multilayer as the source of spin, an energy fluence of ~ 4 J m-2 creates thermal STT sufficient to induce ~ 1 % tilting of the magnetization of a 2 nm-thick CoFeB layer.

  20. Spin coating apparatus

    DOEpatents

    Torczynski, John R.

    2000-01-01

    A spin coating apparatus requires less cleanroom air flow than prior spin coating apparatus to minimize cleanroom contamination. A shaped exhaust duct from the spin coater maintains process quality while requiring reduced cleanroom air flow. The exhaust duct can decrease in cross section as it extends from the wafer, minimizing eddy formation. The exhaust duct can conform to entrainment streamlines to minimize eddy formation and reduce interprocess contamination at minimal cleanroom air flow rates.

  1. The effect of spin in swing bowling in cricket: model trajectories for spin alone

    NASA Astrophysics Data System (ADS)

    Robinson, Garry; Robinson, Ian

    2015-02-01

    significant. For a given amount of spin the amount of side-ways movement increases as the bowler's delivery arm becomes more horizontal. This technique could also be exploited by normal spin bowlers as well as swing bowlers.

  2. Preliminary Tests in the NACA Free-Spinning Wind Tunnel

    NASA Technical Reports Server (NTRS)

    Zimmerman, C H

    1937-01-01

    Typical models and the testing technique used in the NACA free-spinning wind tunnel are described in detail. The results of tests on two models afford a comparison between the spinning characteristics of scale models in the tunnel and of the airplanes that they represent.

  3. Rockets for spin recovery

    NASA Technical Reports Server (NTRS)

    Whipple, R. D.

    1980-01-01

    The potential effectiveness of rockets as an auxiliary means for an aircraft to effect recovery from spins was investigated. The advances in rocket technology produced by the space effort suggested that currently available systems might obviate many of the problems encountered in earlier rocket systems. A modern fighter configuration known to exhibit a flat spin mode was selected. An analytical study was made of the thrust requirements for a rocket spin recovery system for the subject configuration. These results were then applied to a preliminary systems study of rocket components appropriate to the problem. Subsequent spin tunnel tests were run to evaluate the analytical results.

  4. Operator spin foam models

    NASA Astrophysics Data System (ADS)

    Bahr, Benjamin; Hellmann, Frank; Kamiński, Wojciech; Kisielowski, Marcin; Lewandowski, Jerzy

    2011-05-01

    The goal of this paper is to introduce a systematic approach to spin foams. We define operator spin foams, that is foams labelled by group representations and operators, as our main tool. A set of moves we define in the set of the operator spin foams (among other operations) allows us to split the faces and the edges of the foams. We assign to each operator spin foam a contracted operator, by using the contractions at the vertices and suitably adjusted face amplitudes. The emergence of the face amplitudes is the consequence of assuming the invariance of the contracted operator with respect to the moves. Next, we define spin foam models and consider the class of models assumed to be symmetric with respect to the moves we have introduced, and assuming their partition functions (state sums) are defined by the contracted operators. Briefly speaking, those operator spin foam models are invariant with respect to the cellular decomposition, and are sensitive only to the topology and colouring of the foam. Imposing an extra symmetry leads to a family we call natural operator spin foam models. This symmetry, combined with assumed invariance with respect to the edge splitting move, determines a complete characterization of a general natural model. It can be obtained by applying arbitrary (quantum) constraints on an arbitrary BF spin foam model. In particular, imposing suitable constraints on a spin(4) BF spin foam model is exactly the way we tend to view 4D quantum gravity, starting with the BC model and continuing with the Engle-Pereira-Rovelli-Livine (EPRL) or Freidel-Krasnov (FK) models. That makes our framework directly applicable to those models. Specifically, our operator spin foam framework can be translated into the language of spin foams and partition functions. Among our natural spin foam models there are the BF spin foam model, the BC model, and a model corresponding to the EPRL intertwiners. Our operator spin foam framework can also be used for more general spin

  5. PREFACE: Spin Electronics

    NASA Astrophysics Data System (ADS)

    Dieny, B.; Sousa, R.; Prejbeanu, L.

    2007-04-01

    Conventional electronics has in the past ignored the spin on the electron, however things began to change in 1988 with the discovery of giant magnetoresistance in metallic thin film stacks which led to the development of a new research area, so called spin-electronics. In the last 10 years, spin-electronics has achieved a number of breakthroughs from the point of view of both basic science and application. Materials research has led to several major discoveries: very large tunnel magnetoresistance effects in tunnel junctions with crystalline barriers due to a new spin-filtering mechanism associated with the spin-dependent symmetry of the electron wave functions new magnetic tunnelling barriers leading to spin-dependent tunnelling barrier heights and acting as spin-filters magnetic semiconductors with increasingly high ordering temperature. New phenomena have been predicted and observed: the possibility of acting on the magnetization of a magnetic nanostructure with a spin-polarized current. This effect, due to a transfer of angular momentum between the spin polarized conduction electrons and the local magnetization, can be viewed as the reciprocal of giant or tunnel magnetoresistance. It can be used to switch the magnetization of a magnetic nanostructure or to generate steady magnetic excitations in the system. the possibility of generating and manipulating spin current without charge current by creating non-equilibrium local accumulation of spin up or spin down electrons. The range of applications of spin electronics materials and phenomena is expanding: the first devices based on giant magnetoresistance were the magnetoresistive read-heads for computer disk drives. These heads, introduced in 1998 with current-in plane spin-valves, have evolved towards low resistance tunnel magnetoresistice heads in 2005. Besides magnetic recording technology, these very sensitive magnetoresistive sensors are finding applications in other areas, in particular in biology. magnetic

  6. SPIN FLIPPING IN RHIC.

    SciTech Connect

    BAI,M.; LEHRACH,A.; LUCCIO,A.; MACKAY,W.W.; ROSER,T.; TSOUPAS,N.

    2001-06-18

    At the Relativistic Heavy Ion Collider (RHIC), polarized protons will be accelerated and stored for spin physics experiments. Two full helical snakes will be used to eliminate the depolarization due to imperfection and intrinsic spin resonances. Since no resonances are crossed in RHIC, the beam polarization remains fixed through acceleration. However, in order to reduce systematic errors, the experiment often requires the polarization direction reversed. This paper presents a method of using an ac dipole to obtain a full spin flip in the presence of two full snakes [1]. A similar method of using an rf solenoid for spin flip was tested at IUCF [2,3].

  7. Picosecond Spin Seebeck Effect

    NASA Astrophysics Data System (ADS)

    Kimling, Johannes; Choi, Gyung-Min; Brangham, Jack T.; Matalla-Wagner, Tristan; Huebner, Torsten; Kuschel, Timo; Yang, Fengyuan; Cahill, David G.

    2017-02-01

    We report time-resolved magneto-optic Kerr effect measurements of the longitudinal spin Seebeck effect in normal metal /Y3Fe5 O12 bilayers driven by an interfacial temperature difference between electrons and magnons. The measured time evolution of spin accumulation induced by laser excitation indicates transfer of angular momentum across normal metal /Y3Fe5 O12 interfaces on a picosecond time scale, too short for contributions from a bulk temperature gradient in an yttrium iron garnet. The product of spin-mixing conductance and the interfacial spin Seebeck coefficient determined is of the order of 108 A m-2 K-1 .

  8. Neutron spectroscopic factors of 55Ni hole-states from (p,d) transfer reactions

    NASA Astrophysics Data System (ADS)

    Sanetullaev, A.; Tsang, M. B.; Lynch, W. G.; Lee, Jenny; Bazin, D.; Chan, K. P.; Coupland, D.; Henzl, V.; Henzlova, D.; Kilburn, M.; Rogers, A. M.; Sun, Z. Y.; Youngs, M.; Charity, R. J.; Sobotka, L. G.; Famiano, M.; Hudan, S.; Shapira, D.; Peters, W. A.; Barbieri, C.; Hjorth-Jensen, M.; Horoi, M.; Otsuka, T.; Suzuki, T.; Utsuno, Y.

    2014-09-01

    Spectroscopic information has been extracted on the hole-states of 55Ni, the least known of the quartet of nuclei (55Ni, 57Ni, 55Co and 57Cu), one nucleon away from 56Ni, the N=Z=28 double magic nucleus. Using the H1(Ni56,d)Ni55 transfer reaction in inverse kinematics, neutron spectroscopic factors, spins and parities have been extracted for the f7/2, p3/2 and the s1/2 hole-states of 55Ni. These new data provide a benchmark for large basis calculations that include nucleonic orbits in both the sd and pf shells. State of the art calculations have been performed to describe the excitation energies and spectroscopic factors of the s1/2 hole-state below Fermi energy.

  9. Spectroscopic constants and potential energy curves of tungsten carbide

    SciTech Connect

    Balasubramanian, K.

    2000-05-01

    Spectroscopic constants (R{sub e},{omega}{sub e},T{sub e},{mu}{sub e}) and potential energy curves for 40 low-lying electronic states of the diatomic tungsten carbide (WC) were obtained using the complete active space multiconfiguration self-consistent field followed by the multireference singles+doubles configuration interaction and full first- and second-order configuration interaction calculations that included up to 6.4 mil configurations. Spin-orbit effects were included through the enhanced relativistic configuration interaction method described here for 28 electronic states of WC lying below {approx}20 000 cm-1. The spin-orbit splitting of the ground state of WC was found to be very large (4394 cm-1). The ground and excited electronic states of the W atom were also computed and were found to be in good agreement with the experimental data. The nature of bonding was analyzed through the composition of orbitals, leading configurations, Mulliken populations, and dipole moments. The dissociation energy of WC was computed including spin-orbit and electron correlation effects. The recent photoelectron spectra of WC{sup -} were assigned on the basis of our computed results. (c) 2000 American Institute of Physics.

  10. Spectroscopic imaging diagnostics for burning plasma experiments

    NASA Astrophysics Data System (ADS)

    Stutman, D.; Finkenthal, M.; Suliman, G.; Tritz, K.; Delgado-Aparicio, L.; Kaita, R.; Johnson, D.; Soukhanovskii, V.; May, M. J.

    2005-02-01

    Spectroscopic imaging of plasma emission profiles from a few electron volts to tens of kilo-electron volts enables basic diagnostics in present day tokamaks. For the more difficult burning plasma conditions, light extraction and detection techniques, as well as instrument designs need to be investigated. As an alternative to light extraction with reflective optics, we discuss normal incidence, transmissive-diffractive optics (e.g., transmission gratings), which might withstand plasma exposure with less degradation of optical properties. Metallic multilayer reflectors are also of interest for light extraction. Although a shift of the diffraction peak might occur, instrument designs that accommodate such shifts are possible. As imaging detectors we consider "optical" arrays based on conversion of the short-wavelength light into visible light followed by transport of the visible signal with hollow lightguides. The proposed approaches to light extraction and detection could enable radiation resistant diagnostics.

  11. Spectroscopic imaging diagnostics for burning plasma experiments

    SciTech Connect

    Stutman, D.; Finkenthal, M.; Suliman, G.; Tritz, K.; Delgado-Aparicio, L.; Kaita, R.; Johnson, D.; Soukhanovskii, V.; May, M.J.

    2005-02-01

    Spectroscopic imaging of plasma emission profiles from a few electron volts to tens of kilo-electron volts enables basic diagnostics in present day tokamaks. For the more difficult burning plasma conditions, light extraction and detection techniques, as well as instrument designs need to be investigated. As an alternative to light extraction with reflective optics, we discuss normal incidence, transmissive-diffractive optics (e.g., transmission gratings), which might withstand plasma exposure with less degradation of optical properties. Metallic multilayer reflectors are also of interest for light extraction. Although a shift of the diffraction peak might occur, instrument designs that accommodate such shifts are possible. As imaging detectors we consider 'optical' arrays based on conversion of the short-wavelength light into visible light followed by transport of the visible signal with hollow lightguides. The proposed approaches to light extraction and detection could enable radiation resistant diagnostics.

  12. Computational studies of the electronic, conductivities, and spectroscopic properties of hydrolysed Ru(II) anticancer complexes.

    PubMed

    Adeniyi, Adebayo A; Ajibade, Peter A

    2013-11-01

    The mechanism of activation of metal-based anticancer agents was reported to be through hydrolysis. In this study, computational method was used to gain insight to the correlation between the chemistry of the hydrolysis and the anticancer activities of selected Ru(II)-based complexes. Interestingly, we observed that the mechanism of activation by hydrolysis and their consequential anticancer activities is associated with favourable thermodynamic changes, higher hyperpolarizability (β), lower band-gap and higher first-order net current. The Fermi contact (FC) and spin dipole (SD) are found to be the two most significant Ramsey terms that determine the spin-spin couplings (J(HZ)) of most of the existing bonds in the complexes. Many of the computed properties give insights into the change in the chemistry of the complexes due to hydrolysis. Besides strong correlations of the computed properties to the anticancer activities of the complexes, using the quantum theory of atoms in a molecule (QTAIM) to analyse the spectroscopic properties shows a stronger correlation between the spectroscopic properties of Ru atom to the reported anticancer activities than the sum over of the spectroscopic properties of all atoms in the complexes.

  13. Computational studies of the electronic, conductivities, and spectroscopic properties of hydrolysed Ru(II) anticancer complexes

    NASA Astrophysics Data System (ADS)

    Adeniyi, Adebayo A.; Ajibade, Peter A.

    2013-11-01

    The mechanism of activation of metal-based anticancer agents was reported to be through hydrolysis. In this study, computational method was used to gain insight to the correlation between the chemistry of the hydrolysis and the anticancer activities of selected Ru(II)-based complexes. Interestingly, we observed that the mechanism of activation by hydrolysis and their consequential anticancer activities is associated with favourable thermodynamic changes, higher hyperpolarizability (β), lower band-gap and higher first-order net current. The Fermi contact (FC) and spin dipole (SD) are found to be the two most significant Ramsey terms that determine the spin-spin couplings (J(HZ)) of most of the existing bonds in the complexes. Many of the computed properties give insights into the change in the chemistry of the complexes due to hydrolysis. Besides strong correlations of the computed properties to the anticancer activities of the complexes, using the quantum theory of atoms in a molecule (QTAIM) to analyse the spectroscopic properties shows a stronger correlation between the spectroscopic properties of Ru atom to the reported anticancer activities than the sum over of the spectroscopic properties of all atoms in the complexes.

  14. Spectroscopic detection of chemotherapeutics and antioxidants

    NASA Astrophysics Data System (ADS)

    Latka, Ines; Grüner, Roman; Matthäus, Christian; Dietzek, Benjamin; Werncke, W.; Lademann, Jürgen; Popp, Jürgen

    2012-06-01

    The hand-foot-syndrome presents a severe dermal side-effect of chemotherapeutic cancer treatment. The cause of this side-effect is the elimination of systemically administered chemotherapeutics with the sweat. Transported to the skin surface, the drugs subsequently penetrate into the skin in the manner of topically applied substances. Upon accumulation of the chemotherapeutics in the skin the drugs destroy cells and tissue - in the same way as they are supposed to act in cancer cells. Aiming at the development of strategies to illuminate the molecular mechanism underlying the handfoot- syndrome (and, in a second step, strategies to prevent this severe side-effect), it might be important to evaluate the concentration and distribution of chemotherapeutics and antioxidants in the human skin. The latter can be estimated by the carotenoid concentration, as carotenoids serve as marker substances for the dermal antioxidative status.Following the objectives outlined above, this contribution presents a spectroscopic study aiming at the detection and quantification of carotenoids and selected chemotherapeutics in human skin. To this end, spontaneous Raman scattering and coherent anti-Stokes Raman scattering (CARS) microspectroscopy are combined with two-photon excited fluorescence. While the latter technique is Please verify that (1) all pages are present, (2) all figures are correct, (3) all fonts and special characters are correct, and (4) all text and figures fit within the red margin lines shown on this review document. Complete formatting information is available at http://SPIE.org/manuscripts Return to your MySPIE To Do List at http://myspie.org and approve or disapprove this submission. Your manuscript will not be published without this approval.restricted to the detection of fluorescent chemotherapeutics, e.g., doxorubicin, the vibrational spectroscopic techniques can - in principle - be applied to any type of analyte molecules. Furthermore, we will present the

  15. High-spin structure of 134Xe

    NASA Astrophysics Data System (ADS)

    Vogt, A.; Birkenbach, B.; Reiter, P.; Blazhev, A.; Siciliano, M.; Valiente-Dobón, J. J.; Wheldon, C.; Bazzacco, D.; Bowry, M.; Bracco, A.; Bruyneel, B.; Chakrawarthy, R. S.; Chapman, R.; Cline, D.; Corradi, L.; Crespi, F. C. L.; Cromaz, M.; de Angelis, G.; Eberth, J.; Fallon, P.; Farnea, E.; Fioretto, E.; Freeman, S. J.; Gadea, A.; Geibel, K.; Gelletly, W.; Gengelbach, A.; Giaz, A.; Görgen, A.; Gottardo, A.; Hayes, A. B.; Hess, H.; Hua, H.; John, P. R.; Jolie, J.; Jungclaus, A.; Korten, W.; Lee, I. Y.; Leoni, S.; Liang, X.; Lunardi, S.; Macchiavelli, A. O.; Menegazzo, R.; Mengoni, D.; Michelagnoli, C.; Mijatović, T.; Montagnoli, G.; Montanari, D.; Napoli, D.; Pearson, C. J.; Pellegri, L.; Podolyák, Zs.; Pollarolo, G.; Pullia, A.; Radeck, F.; Recchia, F.; Regan, P. H.; Şahin, E.; Scarlassara, F.; Sletten, G.; Smith, J. F.; Söderström, P.-A.; Stefanini, A. M.; Steinbach, T.; Stezowski, O.; Szilner, S.; Szpak, B.; Teng, R.; Ur, C.; Vandone, V.; Ward, D.; Warner, D. D.; Wiens, A.; Wu, C. Y.

    2016-05-01

    Detailed spectroscopic information on the N ˜82 nuclei is necessary to benchmark shell-model calculations in the region. The nuclear structure above long-lived isomers in 134Xe is investigated after multinucleon transfer (MNT) and actinide fission. Xenon-134 was populated as (i) a transfer product in 238U+ 136Xe and 208Pb+ 136Xe MNT reactions and (ii) as a fission product in the 238U+ 136Xe reaction employing the high-resolution Advanced Gamma Tracking Array (AGATA). Trajectory reconstruction has been applied for the complete identification of beamlike transfer products with the magnetic spectrometer PRISMA. The 198Pt 136Xe MNT reaction was studied with the γ -ray spectrometer GAMMASPHERE in combination with the gas detector array Compact Heavy Ion Counter (CHICO). Several high-spin states in 134Xe on top of the two long-lived isomers are discovered based on γ γ -coincidence relationships and information on the γ -ray angular distributions as well as excitation energies from the total kinetic energy loss and fission fragments. The revised level scheme of 134Xe is extended up to an excitation energy of 5.832 MeV with tentative spin-parity assignments up to 16+. Previous assignments of states above the 7- isomer are revised. Latest shell-model calculations employing two different effective interactions reproduce the experimental findings and support the new spin and parity assignments.

  16. Spin Pumping and Measurement of Spin Currents in Optical Superlattices

    NASA Astrophysics Data System (ADS)

    Schweizer, C.; Lohse, M.; Citro, R.; Bloch, I.

    2016-10-01

    We report on the experimental implementation of a spin pump with ultracold bosonic atoms in an optical superlattice. In the limit of isolated double wells, it represents a 1D dynamical version of the quantum spin Hall effect. Starting from an antiferromagnetically ordered spin chain, we periodically vary the underlying spin-dependent Hamiltonian and observe a spin current without charge transport. We demonstrate a novel detection method to measure spin currents in optical lattices via superexchange oscillations emerging after a projection onto static double wells. Furthermore, we directly verify spin transport through in situ measurements of the spins' center-of-mass displacement.

  17. Spin Pumping and Measurement of Spin Currents in Optical Superlattices.

    PubMed

    Schweizer, C; Lohse, M; Citro, R; Bloch, I

    2016-10-21

    We report on the experimental implementation of a spin pump with ultracold bosonic atoms in an optical superlattice. In the limit of isolated double wells, it represents a 1D dynamical version of the quantum spin Hall effect. Starting from an antiferromagnetically ordered spin chain, we periodically vary the underlying spin-dependent Hamiltonian and observe a spin current without charge transport. We demonstrate a novel detection method to measure spin currents in optical lattices via superexchange oscillations emerging after a projection onto static double wells. Furthermore, we directly verify spin transport through in situ measurements of the spins' center-of-mass displacement.

  18. Effect of spin rotation coupling on spin transport

    SciTech Connect

    Chowdhury, Debashree Basu, B.

    2013-12-15

    We have studied the spin rotation coupling (SRC) as an ingredient to explain different spin-related issues. This special kind of coupling can play the role of a Dresselhaus like coupling in certain conditions. Consequently, one can control the spin splitting, induced by the Dresselhaus like term, which is unusual in a semiconductor heterostructure. Within this framework, we also study the renormalization of the spin-dependent electric field and spin current due to the k{sup →}⋅p{sup →} perturbation, by taking into account the interband mixing in the rotating system. In this paper we predict the enhancement of the spin-dependent electric field resulting from the renormalized spin rotation coupling. The renormalization factor of the spin electric field is different from that of the SRC or Zeeman coupling. The effect of renormalized SRC on spin current and Berry curvature is also studied. Interestingly, in the presence of this SRC-induced SOC it is possible to describe spin splitting as well as spin galvanic effect in semiconductors. -- Highlights: •Studied effect of spin rotation coupling on the spin electric field, spin current and Berry curvature. •In the k{sup →}⋅p{sup →} framework we study the renormalization of spin electric field and spin current. •For an inertial system we have discussed the spin splitting. •Expression for the Berry phase in the inertial system is discussed. •The inertial spin galvanic effect is studied.

  19. Advanced solid-state carbon-13 nuclear magnetic resonance spectroscopic studies of sewage sludge organic matter: detection of organic "domains".

    PubMed

    Smernik, Ronald J; Oliver, Ian W; Merrington, Graham

    2003-01-01

    Two novel solid-state 13C nuclear magnetic resonance (NMR) spectroscopic techniques, PSRE (proton spin relaxation editing) and RESTORE [Restoration of Spectra via T(CH) and T(1rho)H (T One Rho H) Editing], were used to provide detailed chemical characterization of the organic matter from six Australian sewage sludges. These methods were used to probe the submicrometer heterogeneity of sludge organic matter, and identify and quantify spatially distinct components. Analysis of the T1H relaxation behavior of the sludges indicated that each sludge contained two types of organic domains. Carbon-13 PSRE NMR subspectra were generated to determine the chemical nature of these domains. The rapidly relaxing component of each sludge was rich in protein and alkyl carbon, and was identified as dead bacterial material. The slowly relaxing component of each sludge was rich in carbohydrate and lignin structures, and was identified as partly degraded plant material. The bacterial domains were shown, using the RESTORE technique, to also have characteristically rapid T(1rho)H relaxation rates. This rapid T(1rho)H relaxation was identified as the main cause of underrepresentation of these domains in standard 13C cross polarization (CP) NMR spectra of sludges. The heterogeneous nature of sewage sludge organic matter has implications for land application of sewage sludge, since the two components are likely to have different capacities for sorbing organic and inorganic toxicants present in sewage sludge, and will decompose at different rates.

  20. Intrinsic spin polarized electronic structure of CrO{sub 2} epitaxial film revealed by bulk-sensitive spin-resolved photoemission spectroscopy

    SciTech Connect

    Fujiwara, Hirokazu; Sunagawa, Masanori; Kittaka, Tomoko; Terashima, Kensei; Wakita, Takanori; Muraoka, Yuji; Yokoya, Takayoshi

    2015-05-18

    We have performed bulk-sensitive spin-resolved photoemission spectroscopy in order to clarify the intrinsic spin-resolved electronic states of half-metallic ferromagnet CrO{sub 2}. We used CrO{sub 2} epitaxial films on TiO{sub 2}(100), which shows a peak at 1 eV with a clear Fermi edge, consistent with the bulk-sensitive PES spectrum for CrO{sub 2}. In spin-resolved spectra at 40 K, while the Fermi edge was observed in the spin up (majority spin) state, no states at the Fermi level (E{sub F}) with an energy gap of 0.5 eV below E{sub F} were observed in the spin down (minority spin) state. At 300 K, the gap in the spin down state closes. These results are consistent with resistivity measurements and magnetic hysteresis curves of the fabricated CrO{sub 2} film, constituting spectroscopic evidence for the half-metallicity of CrO{sub 2} at low temperature and reducing the spin polarization at room temperature. We also discuss the electron correlation effects of Cr 3d.