Kinetic and spectral descriptions of autoionization phenomena associated with atomic processes in plasmas

Science.gov (United States)

Jacobs, Verne L.

2017-06-01

This investigation has been devoted to the theoretical description and computer modeling of atomic processes giving rise to radiative emission in energetic electron and ion beam interactions and in laboratory plasmas. We are also interested in the effects of directed electron and ion collisions and of anisotropic electric and magnetic fields. In the kinetic-theory description, we treat excitation, de-excitation, ionization, and recombination in electron and ion encounters with partially ionized atomic systems, including the indirect contributions from processes involving autoionizing resonances. These fundamental collisional and electromagnetic interactions also provide particle and photon transport mechanisms. From the spectral perspective, the analysis of atomic radiative emission can reveal detailed information on the physical properties in the plasma environment, such as non-equilibrium electron and charge-state distributions as well as electric and magnetic field distributions. In this investigation, a reduced-density-matrix formulation is developed for the microscopic description of atomic electromagnetic interactions in the presence of environmental (collisional and radiative) relaxation and decoherence processes. Our central objective is a fundamental microscopic description of atomic electromagnetic processes, in which both bound-state and autoionization-resonance phenomena can be treated in a unified and self-consistent manner. The time-domain (equation-of-motion) and frequency-domain (resolvent-operator) formulations of the reduced-density-matrix approach are developed in a unified and self-consistent manner. This is necessary for our ultimate goal of a systematic and self-consistent treatment of non-equilibrium (possibly coherent) atomic-state kinetics and high-resolution (possibly overlapping) spectral-line shapes. We thereby propose the introduction of a generalized collisional-radiative atomic-state kinetics model based on a reduced

Ultrafast atomic process in X-ray emission by using inner-shell ionization method for sodium and carbon atoms

Energy Technology Data Exchange (ETDEWEB)

Moribayashi, Kengo; Sasaki, Akira; Tajima, Toshiki [Japan Atomic Energy Research Inst., Neyagawa, Osaka (Japan). Kansai Research Establishment

1998-07-01

An ultrafast inner-shell ionization process with X-ray emission stimulated by high-intensity short-pulse X-ray is studied. Carbon and sodium atoms are treated as target matter. It is shown that atomic processes of the target determine the necessary X-ray intensity for X-ray laser emission as well as the features of X-ray laser such as wavelength and duration time. The intensity also depends on the density of initial atoms. Furthermore, we show that as the intensity of X-ray source becomes high, the multi-inner-shell ionization predominates, leading to the formation of hollow atoms. As the density of hollow atoms is increased by the pumping X-ray power, the emission of X-rays is not only of significance for high brightness X-ray measurement but also is good for X-ray lasing. New classes of experiments of pump X-ray probe and X-ray laser are suggested. (author)

Inductively coupled plasma-atomic emission spectroscopy

International Nuclear Information System (INIS)

Winge, R.K.; Fassel, V.A.; Peterson, V.J.; Floyd, M.A.

1985-01-01

This atlas of inductively coupled plasma-atomic emission spectroscopy records the spectra of the elements in a way that would reveal the general nature of the spectra, in all their simplicity or complexity; and offers a definitive summary of the most prominent spectral lines of the elements, i.e., those most likely to be useful for the determination of trace and ultratrace concentrations; it provides reliable estimates, based on the recorded experimental spectra, of the powers of detection of the listed prominent lines; and assesses the very important problem of spectral interferences. The atlas is composed of three main sections. Part I is concerned with the historical aspects of compilations of spectral information. Part II is based on 232 wavelength scans of 70 elements. Each of the wavelength scans covers an 80 nm spectral region. These scans allow a rapid comparison of the background and spectral line intensities emitted in the ICP and provide a ready means for identification of the most prominent lines of each element and for estimation of the trace element analytical capabilities of these lines. A listing of 973 prominent lines with associated detection limits is also presented. Part III addresses the problem of spectral interferences. On this topic a detailed collection of coincidence profiles is presented for 281 of the most prominent lines, each with profiles of ten of the most prevalent concomitants superimposed. (Auth.)

High temperature spectral emissivity measurement using integral blackbody method

Science.gov (United States)

Pan, Yijie; Dong, Wei; Lin, Hong; Yuan, Zundong; Bloembergen, Pieter

2016-10-01

Spectral emissivity is a critical material's thermos-physical property for heat design and radiation thermometry. A prototype instrument based upon an integral blackbody method was developed to measure material's spectral emissivity above 1000 °. The system was implemented with an optimized commercial variable-high-temperature blackbody, a high speed linear actuator, a linear pyrometer, and an in-house designed synchronization circuit. A sample was placed in a crucible at the bottom of the blackbody furnace, by which the sample and the tube formed a simulated blackbody which had an effective total emissivity greater than 0.985. During the measurement, the sample was pushed to the end opening of the tube by a graphite rod which was actuated through a pneumatic cylinder. A linear pyrometer was used to monitor the brightness temperature of the sample surface through the measurement. The corresponding opto-converted voltage signal was fed and recorded by a digital multi-meter. A physical model was proposed to numerically evaluate the temperature drop along the process. Tube was discretized as several isothermal cylindrical rings, and the temperature profile of the tube was measurement. View factors between sample and rings were calculated and updated along the whole pushing process. The actual surface temperature of the sample at the end opening was obtained. Taking advantages of the above measured voltage profile and the calculated true temperature, spectral emissivity under this temperature point was calculated.

Modification and control of the spontaneous emission from an M-type atom embedded in an anisotropic photonic crystal

International Nuclear Information System (INIS)

Ding Chunling; Li Jiahua; Yang Xiaoxue; Lue Xinyou

2011-01-01

We describe the spontaneous emission properties of an M-type five-level atom embedded in a photonic crystal (PC), which is coherently driven by two external laser fields. It leads to two types of quantum interference: reservoir-induced interference and laser-induced interference. Considering different detunings of atomic transition frequencies from band edges, we reveal some interesting phenomena such as spectral-line enhancement, spectral-line suppression, spectral-line narrowing, reservoir-induced cancellation of spontaneous emission and the appearance of dark lines, which originate from the quantum interference effects and the control of external laser fields. These investigations suggest possible applications in quantum optics, optical communications and in the fabrication of novel optoelectronic devices.

Emissivity compensated spectral pyrometry—algorithm and sensitivity analysis

International Nuclear Information System (INIS)

Hagqvist, Petter; Sikström, Fredrik; Christiansson, Anna-Karin; Lennartson, Bengt

2014-01-01

In order to solve the problem of non-contact temperature measurements on an object with varying emissivity, a new method is herein described and evaluated. The method uses spectral radiance measurements and converts them to temperature readings. It proves to be resilient towards changes in spectral emissivity and tolerates noisy spectral measurements. It is based on an assumption of smooth changes in emissivity and uses historical values of spectral emissivity and temperature for estimating current spectral emissivity. The algorithm, its constituent steps and accompanying parameters are described and discussed. A thorough sensitivity analysis of the method is carried out through simulations. No rigorous instrument calibration is needed for the presented method and it is therefore industrially tractable. (paper)

Quenching of the OH and nitrogen molecular emission by methane addition in an Ar capacitively coupled plasma to remove spectral interference in lead determination by atomic fluorescence spectrometry

Energy Technology Data Exchange (ETDEWEB)

Frentiu, T., E-mail: ftibi@chem.ubbcluj.r [Faculty of Chemistry and Chemical Engineering, Babes-Bolyai University, Arany Janos 11, 400028 Cluj-Napoca (Romania); Ponta, M., E-mail: mponta@chem.ubbcluj.r [Faculty of Chemistry and Chemical Engineering, Babes-Bolyai University, Arany Janos 11, 400028 Cluj-Napoca (Romania); Mihaltan, A.I., E-mail: alinblaj2005@yahoo.co [National Institute for Research and Development of Optoelectronics Bucharest - Research Institute for Analytical Instrumentation, Donath 67, 400293 Cluj-Napoca (Romania); Darvasi, E., E-mail: edarvasi@chem.ubbcluj.r [Faculty of Chemistry and Chemical Engineering, Babes-Bolyai University, Arany Janos 11, 400028 Cluj-Napoca (Romania); Frentiu, M., E-mail: frentiu.maria@yahoo.co [National Institute for Research and Development of Optoelectronics Bucharest - Research Institute for Analytical Instrumentation, Donath 67, 400293 Cluj-Napoca (Romania); Cordos, E., E-mail: emilcordos@gmail.co [National Institute for Research and Development of Optoelectronics Bucharest - Research Institute for Analytical Instrumentation, Donath 67, 400293 Cluj-Napoca (Romania)

2010-07-15

A new method is proposed to remove the spectral interference on elements in atomic fluorescence spectrometry by quenching of the molecular emission of the OH radical (A{sup 2{Sigma}+} {yields} X{sup 2{Pi}}) and N{sub 2} second positive system (C{sup 3{Pi}}{sub u} {yields} B{sup 3{Sigma}}{sub g}) in the background spectrum of medium power Ar plasmas. The experiments were carried out in a radiofrequency capacitively coupled plasma (275 W, 27.12 MHz) by CH{sub 4} addition. The quenching is the result of the high affinity of OH radical for a hydrogen atom from the CH{sub 4} molecule and the collisions of the second kind between nitrogen excited molecules and CH{sub 4}, respectively. The decrease of the emission of N{sub 2} second positive system in the presence of CH{sub 4} is also the result of the deactivation of the metastable argon atoms that could excite the nitrogen molecules. For flow rates of 0.7 l min{sup -1} Ar with addition of 7.5 ml min{sup -1} CH{sub 4}, the molecular emission of OH and N{sub 2} was completely removed from the plasma jet spectrum at viewing heights above 60 mm. The molecular emission associated to CH and CH{sub 2} species was not observed in the emission spectrum of Ar/CH{sub 4} plasma in the ultraviolet range. The method was experimented for the determination of Pb at 283.31 nm by atomic fluorescence spectrometry with electrodeless discharge lamp and a multichannel microspectrometer. The detection limit was 35 ng ml{sup -1}, 2-3 times better than in atomic emission spectrometry using the same plasma source, and similar to that in hollow cathode lamp microwave plasma torch atomic fluorescence spectrometry.

Emission Spectrum Property of Modulated Atom-Field Coupling System

International Nuclear Information System (INIS)

Gao Yun-Feng; Feng Jian; Li Yue-Ke

2013-01-01

The emission spectrum of a two-level atom interacting with a single mode radiation field in the case of periodic oscillation coupling coefficient is investigated. A general expression for the emission spectrum is derived. The numerical results for the initial field in pure number stare are calculated. It is found that the effect of the coupling coefficient modulation on the spectral structure is very obvious in the case of a low modulation frequency and larger amplitude when the initial field is vacuum, which is potentially useful for exploring a modulated light source. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

Spontaneous emission by moving atoms

International Nuclear Information System (INIS)

Meystre, P.; Wilkens, M.

1994-01-01

It is well known that spontaneous emission is not an intrinsic atomic property, but rather results from the coupling of the atom to the vacuum modes of the electromagnetic field. As such, it can be modified by tailoring the electromagnetic environment into which the atom can radiate. This was already realized by Purcell, who noted that the spontaneous emission rate can be enhanced if the atom placed inside a cavity is resonant with one of the cavity is resonant with one of the cavity modes, and by Kleppner, who discussed the opposite case of inhibited spontaneous emission. It has also been recognized that spontaneous emission need not be an irreversible process. Indeed, a system consisting of a single atom coupled to a single mode of the electromagnetic field undergoes a periodic exchange of excitation between the atom and the field. This periodic exchange remains dominant as long as the strength of the coupling between the atom and a cavity mode is itself dominant. 23 refs., 6 figs

Induced absorption and stimulated emission in a driven two-level atom

International Nuclear Information System (INIS)

Mavroyannis, C.

1992-01-01

We have considered the induced processes that occur in a driven two-level atom, where a laser photon is absorbed and emitted by the ground and by the excited states of the atom, respectively. In the low-intensity limit of the laser field, the induced spectra arising when a laser photon is absorbed by the ground state of the atom consist of two peaks describing induced absorption and stimulated-emission processes, respectively, where the former prevails over the latter. Asymmetry of the spectral lines occurs at off-resonance and its extent depends on the detuning of the laser field. The physical. process where a laser photon is emitted by the excited state is the reverse of that arising from the absorption of a laser photon by the ground state of the atom. The former differs from the latter in that the emission of a laser photon by the excited state occurs in the low frequency regime and that the stimulated-emission process prevails over that of the induced absorption. In this case, amplification of ultrashort pulses is likely to occur without the need of population inversion between the optical transitions. The computed spectra are graphically presented and discussed. (author)

FREQUENCY REDISTRIBUTION OF POLARIZED LIGHT IN THE Λ-TYPE MULTI-TERM POLARIZED ATOM

Energy Technology Data Exchange (ETDEWEB)

Casini, R. [High Altitude Observatory, National Center for Atmospheric Research, P.O. Box 3000, Boulder, CO 80307-3000 (United States); Sainz, R. Manso [Max-Planck-Institut für Sonnensystemforschung, Justus-von-Liebig-Weg 3, D-37077 Göttingen (Germany)

2016-06-20

We study the effects of Rayleigh and Raman scattering on the formation of polarized spectral lines in a Λ-type multi-term atom. We fully take into account the partial redistribution of frequency and the presence of atomic polarization in the lower states of the atomic model. Problems that can be modeled with this formalism include, for example, the formation of the Ca ii H–K and IR triplet, the analogous system of Ba ii, and the Ly β –H α system of hydrogenic ions.

New Equations for Calculating Principal and Fine-Structure Atomic Spectra for Single and Multi-Electron Atoms

Energy Technology Data Exchange (ETDEWEB)

Surdoval, Wayne A. [National Energy Technology Lab. (NETL), Pittsburgh, PA, (United States); Berry, David A. [National Energy Technology Lab. (NETL), Morgantown, WV (United States); Shultz, Travis R. [National Energy Technology Lab. (NETL), Morgantown, WV (United States)

2018-03-09

A set of equations are presented for calculating atomic principal spectral lines and fine-structure energy splits for single and multi-electron atoms. Calculated results are presented and compared to the National Institute of Science and Technology database demonstrating very good accuracy. The equations do not require fitted parameters. The only experimental parameter required is the Ionization energy for the electron of interest. The equations have comparable accuracy and broader applicability than the single electron Dirac equation. Three Appendices discuss the origin of the new equations and present calculated results. New insights into the special relativistic nature of the Dirac equation and its relationship to the new equations are presented.

Online Multi-Spectral Meat Inspection

DEFF Research Database (Denmark)

Nielsen, Jannik Boll; Larsen, Anders Boesen Lindbo

2013-01-01

We perform an explorative study on multi-spectral image data from a prototype device developed for fast online quality inspection of meat products. Because the camera setup is built for speed, we sacrifice exact pixel correspondences between the different bands of the multi-spectral images. Our...... work is threefold as we 1) investigate the color distributions and construct a model to describe pork loins, 2) classify the different components in pork loins (meat, fat, membrane), and 3) detect foreign objects on the surface of pork loins. Our investigation shows that the color distributions can...

Multi-Color QWIP FPAs for Hyperspectral Thermal Emission Instruments

Science.gov (United States)

Soibel, Alexander; Luong, Ed; Mumolo, Jason M.; Liu, John; Rafol, Sir B.; Keo, Sam A.; Johnson, William; Willson, Dan; Hill, Cory J.; Ting, David Z.-Y.;

Automated installation for atomic emission determination of gold, silver and platinum group metals

International Nuclear Information System (INIS)

Zayakina, S.B.; Anoshin, G.N.; Gerasimov, P.A.; Smirnov, A.V.

1999-01-01

An automated installation for the direct atomic emission determination of silver, gold and platinum-group metals (Ru) in geological and geochemical materials with software for automated data acquisition and handling is designed and developed. The installation consists of a DFS-458 diffraction spectrograph, a MAES-10 multichannel analyzer of emission spectra, and a dual-jet plasmatron. A library of spectral lines of almost all elements excited in the dual-jet plasmatron is complied [ru

Multi-spectral confocal microendoscope for in-vivo imaging

Science.gov (United States)

Rouse, Andrew Robert

The concept of in-vivo multi-spectral confocal microscopy is introduced. A slit-scanning multi-spectral confocal microendoscope (MCME) was built to demonstrate the technique. The MCME employs a flexible fiber-optic catheter coupled to a custom built slit-scan confocal microscope fitted with a custom built imaging spectrometer. The catheter consists of a fiber-optic imaging bundle linked to a miniature objective and focus assembly. The design and performance of the miniature objective and focus assembly are discussed. The 3mm diameter catheter may be used on its own or routed though the instrument channel of a commercial endoscope. The confocal nature of the system provides optical sectioning with 3mum lateral resolution and 30mum axial resolution. The prism based multi-spectral detection assembly is typically configured to collect 30 spectral samples over the visible chromatic range. The spectral sampling rate varies from 4nm/pixel at 490nm to 8nm/pixel at 660nm and the minimum resolvable wavelength difference varies from 7nm to 18nm over the same spectral range. Each of these characteristics are primarily dictated by the dispersive power of the prism. The MCME is designed to examine cellular structures during optical biopsy and to exploit the diagnostic information contained within the spectral domain. The primary applications for the system include diagnosis of disease in the gastro-intestinal tract and female reproductive system. Recent data from the grayscale imaging mode are presented. Preliminary multi-spectral results from phantoms, cell cultures, and excised human tissue are presented to demonstrate the potential of in-vivo multi-spectral imaging.

Multi spectral scaling data acquisition system

International Nuclear Information System (INIS)

Behere, Anita; Patil, R.D.; Ghodgaonkar, M.D.; Gopalakrishnan, K.R.

1997-01-01

In nuclear spectroscopy applications, it is often desired to acquire data at high rate with high resolution. With the availability of low cost computers, it is possible to make a powerful data acquisition system with minimum hardware and software development, by designing a PC plug-in acquisition board. But in using the PC processor for data acquisition, the PC can not be used as a multitasking node. Keeping this in view, PC plug-in acquisition boards with on-board processor find tremendous applications. Transputer based data acquisition board has been designed which can be configured as a high count rate pulse height MCA or as a Multi Spectral Scaler. Multi Spectral Scaling (MSS) is a new technique, in which multiple spectra are acquired in small time frames and are then analyzed. This paper describes the details of this multi spectral scaling data acquisition system. 2 figs

Optically trapped atomic resonant devices for narrow linewidth spectral imaging

Science.gov (United States)

Qian, Lipeng

absorption and fluorescence. The optimum resolution of the fluorescent image is predicted by simulation. Radiation trapping is also shown to be useful for the generation of ultra-narrow linewidth light from an atomic vapor flash lamp. A 2 nanosecond, high voltage pulse is used to excite low pressure mercury vapor mixed with noble gases, producing high intensity emission at the mercury resonant line at 253.7 nm. With a nanosecond pumping time and high electrical current, the radiation intensity of the mercury discharge is increased significantly compared to a normal glow discharge lamp, while simultaneously suppressing the formation of an arc discharge. By avoiding the arc discharge, discrete spectral lines of mercury were kept at narrow bandwidth. Due to radiation trapping, the emission linewidth from the nanosecond mercury lamp decreases with time and produces ultra-narrow linewidth emission 100 ns after of the excitation, this linewidth is verified by absorption measurements through low pressure mercury absorption filter. The lamp is used along with mercury absorption filters for spectroscopic applications, including Filtered Rayleigh Scattering with different CO2 pressures and Raman scattering from methanol.

The multi-spectral line-polarization MSE system on Alcator C-Mod

Energy Technology Data Exchange (ETDEWEB)

Mumgaard, R. T., E-mail: mumgaard@psfc.mit.edu; Khoury, M. [Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Scott, S. D. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08540 (United States)

2016-11-15

A multi-spectral line-polarization motional Stark effect (MSE-MSLP) diagnostic has been developed for the Alcator C-Mod tokamak wherein the Stokes vector is measured in multiple wavelength bands simultaneously on the same sightline to enable better polarized background subtraction. A ten-sightline, four wavelength MSE-MSLP detector system was designed, constructed, and qualified. This system consists of a high-throughput polychromator for each sightline designed to provide large étendue and precise spectral filtering in a cost-effective manner. Each polychromator utilizes four narrow bandpass interference filters and four custom large diameter avalanche photodiode detectors. Two filters collect light to the red and blue of the MSE emission spectrum while the remaining two filters collect the beam pi and sigma emission generated at the same viewing volume. The filter wavelengths are temperature tuned using custom ovens in an automated manner. All system functions are remote controllable and the system can be easily retrofitted to existing single-wavelength line-polarization MSE systems.

The multi-spectral line-polarization MSE system on Alcator C-Mod

International Nuclear Information System (INIS)

Mumgaard, R. T.; Khoury, M.; Scott, S. D.

2016-01-01

A multi-spectral line-polarization motional Stark effect (MSE-MSLP) diagnostic has been developed for the Alcator C-Mod tokamak wherein the Stokes vector is measured in multiple wavelength bands simultaneously on the same sightline to enable better polarized background subtraction. A ten-sightline, four wavelength MSE-MSLP detector system was designed, constructed, and qualified. This system consists of a high-throughput polychromator for each sightline designed to provide large étendue and precise spectral filtering in a cost-effective manner. Each polychromator utilizes four narrow bandpass interference filters and four custom large diameter avalanche photodiode detectors. Two filters collect light to the red and blue of the MSE emission spectrum while the remaining two filters collect the beam pi and sigma emission generated at the same viewing volume. The filter wavelengths are temperature tuned using custom ovens in an automated manner. All system functions are remote controllable and the system can be easily retrofitted to existing single-wavelength line-polarization MSE systems.

Determination of trace elements in soy milk using ICP atomic emission spectrometry

International Nuclear Information System (INIS)

Tanaka, Satoko; Chayama, Kenji

2009-01-01

The present study investigated the optimal method for the multi-element quantification of 9 elements in soy milk: calcium, copper, iron, potassium, magnesium, manganese, sodium, phosphorus, and zinc. Results obtained using ICP atomic emission spectrometry were compared with those obtained by atomic absorption spectrometry, which is the standard method. The same sample was measured using both ICP atomic emission spectrometry and atomic absorption spectrometry. The percentage of minerals recovered by ICP atomic emission spectrometry ranged from 99.3% to 102%, which was equivalent to that by atomic absorption spectrometry. Therefore, a good result with standard deviation was obtained. The mineral contents of 16 samples of commercially-available soy milk products were measured. The Cu content was significantly proportional to the amount of soybean solids (P < 0.001). Moreover, although relation-ships did not attain statistical significance, the consents of Fe, Zn, K, Mg and P were proportional to the amount of soybean solids, and were highest in soy milk, followed by prepared soy milk and so milk beverage. The Ca content of modified soy milk was significantly higher than that of soy milk and soy milk-based beverages (P < 0.001). Furthermore, the Na content in soy milk was significantly lower. (author)

Spectral evolution of energetic neutral atom emissions at the heliospheric poles as measured by IBEX during its first three years

Energy Technology Data Exchange (ETDEWEB)

Dayeh, M. A.; Allegrini, F.; Desai, M. I.; Ebert, R. W.; Fuselier, S. A.; Livadiotis, G.; McComas, D. J.; Schwadron, N. A. [Southwest Research Institute, San Antonio, TX 78228 (United States); DeMajistre, R. [Johns Hopkins University Applied Physics Laboratory, Laurel, MD 20723 (United States); Janzen, P.; Reisenfeld, D. [University of Montana, Missoula, MT 59812 (United States); Siewert, M., E-mail: maldayeh@swri.edu [Institut für Astronomie der Universität Bonn, Abteilung f. Astrophysik und Extraterrestrische Forschung, Auf dem Hügel 71, D-53121 Bonn (Germany)

2014-12-10

The Interstellar Boundary Explorer (IBEX) mission continues to measure energetic neutral atom (ENA) emissions produced by charge exchange between solar wind (SW) protons and interstellar neutrals at the edge of our heliosphere. Using the first 3 yr of IBEX-Hi ENA measurements (2009-2011), we examined the spectral evolution of ∼0.5-6 keV ENAs at the polar regions (above 60°). We found the following: (1) pixels with a characteristic 'ankle' spectra (lower spectral index at higher energies) increase by ∼5% in 2010 and ∼10% in 2011 compared to 2009. (2) The averaged spectral index in 2011 is smaller than that of 2009. (3) The slope of the ENA spectrum above ∼1.7 keV is more variable than the slope below ∼1.7 keV. The lower spectral index at higher energies of the spectrum does not appear to be caused by an increase of the ENA production at these energies, but rather from a consistent decrease at lower energies. (4) The decrease in polar ENA fluxes does not correlate significantly with the averaged SW dynamic pressure, back-traced in time to 1 AU along the flow streamlines (originating between 10° and 30° for slow SW, and 60° and 80° for fast SW), assuming these are the respective conditions of ENA progenitors back in time. These results provide insights into the complexity of relating the slow and fast SW contributions to polar ENAs and shed light on how the solar output and the resulting change in the global heliospheric structure possibly affect the heliosheath (HS) populations.

Precise Multi-Spectral Dermatological Imaging

DEFF Research Database (Denmark)

Gomez, David Delgado; Carstensen, Jens Michael; Ersbøll, Bjarne Kjær

2004-01-01

In this work, an integrated imaging system to obtain accurate and reproducible multi-spectral dermatological images is proposed. The system is made up of an integrating sphere, light emitting diodes and a generic monochromatic camera. The system can collect up to 10 different spectral bands....... These spectral bands vary from ultraviolet to near infrared. The welldefined and diffuse illumination of the optically closed scene aims to avoid shadows and specular reflections. Furthermore, the system has been developed to guarantee the reproducibility of the collected images. This allows for comparative...

Atomic spectral-product representations of molecular electronic structure: metric matrices and atomic-product composition of molecular eigenfunctions.

Science.gov (United States)

Ben-Nun, M; Mills, J D; Hinde, R J; Winstead, C L; Boatz, J A; Gallup, G A; Langhoff, P W

2009-07-02

Recent progress is reported in development of ab initio computational methods for the electronic structures of molecules employing the many-electron eigenstates of constituent atoms in spectral-product forms. The approach provides a universal atomic-product description of the electronic structure of matter as an alternative to more commonly employed valence-bond- or molecular-orbital-based representations. The Hamiltonian matrix in this representation is seen to comprise a sum over atomic energies and a pairwise sum over Coulombic interaction terms that depend only on the separations of the individual atomic pairs. Overall electron antisymmetry can be enforced by unitary transformation when appropriate, rather than as a possibly encumbering or unnecessary global constraint. The matrix representative of the antisymmetrizer in the spectral-product basis, which is equivalent to the metric matrix of the corresponding explicitly antisymmetric basis, provides the required transformation to antisymmetric or linearly independent states after Hamiltonian evaluation. Particular attention is focused in the present report on properties of the metric matrix and on the atomic-product compositions of molecular eigenstates as described in the spectral-product representations. Illustrative calculations are reported for simple but prototypically important diatomic (H(2), CH) and triatomic (H(3), CH(2)) molecules employing algorithms and computer codes devised recently for this purpose. This particular implementation of the approach combines Slater-orbital-based one- and two-electron integral evaluations, valence-bond constructions of standard tableau functions and matrices, and transformations to atomic eigenstate-product representations. The calculated metric matrices and corresponding potential energy surfaces obtained in this way elucidate a number of aspects of the spectral-product development, including the nature of closure in the representation, the general redundancy or

Passive microrheology of soft materials with atomic force microscopy: A wavelet-based spectral analysis

Energy Technology Data Exchange (ETDEWEB)

Martinez-Torres, C.; Streppa, L. [CNRS, UMR5672, Laboratoire de Physique, Ecole Normale Supérieure de Lyon, 46 Allée d' Italie, Université de Lyon, 69007 Lyon (France); Arneodo, A.; Argoul, F. [CNRS, UMR5672, Laboratoire de Physique, Ecole Normale Supérieure de Lyon, 46 Allée d' Italie, Université de Lyon, 69007 Lyon (France); CNRS, UMR5798, Laboratoire Ondes et Matière d' Aquitaine, Université de Bordeaux, 351 Cours de la Libération, 33405 Talence (France); Argoul, P. [Université Paris-Est, Ecole des Ponts ParisTech, SDOA, MAST, IFSTTAR, 14-20 Bd Newton, Cité Descartes, 77420 Champs sur Marne (France)

2016-01-18

Compared to active microrheology where a known force or modulation is periodically imposed to a soft material, passive microrheology relies on the spectral analysis of the spontaneous motion of tracers inherent or external to the material. Passive microrheology studies of soft or living materials with atomic force microscopy (AFM) cantilever tips are rather rare because, in the spectral densities, the rheological response of the materials is hardly distinguishable from other sources of random or periodic perturbations. To circumvent this difficulty, we propose here a wavelet-based decomposition of AFM cantilever tip fluctuations and we show that when applying this multi-scale method to soft polymer layers and to living myoblasts, the structural damping exponents of these soft materials can be retrieved.

Non-linear interactions of multi-level atoms with a near-resonant standing wave

International Nuclear Information System (INIS)

O'Kane, T.J.; Scholten, R.E.; Walkiewicz, M.R.; Farrell, P.M.

1998-01-01

Using a semiclassical density matrix formalism we have calculated the behavior of multi-level atoms interacting with a standing wave field, and show how complex non-linear phenomena, including multi-photon effects, combine to produce saturation spectra as observed in experiments. We consider both 20-level sodium and 24-level rubidium models, contrasting these with a simple 2-level case. The influence of parameters such as atomic trajectory and the time the atom remains in the beam are shown to have a critical effect on the lineshape of these resonances and the emission/absorption processes. Stable oscillations in the excited state populations for both the two-level and multi-level cases are shown to be limit cycles. These limit cycles undergo period doubling as the system evolves into chaos. Finally, using a Monte Carlo treatment, these processes average to produce saturated absorption spectra complete with power and Doppler broadening effects consistent with experiment. (authors)

Determination of rare earth elements in aluminum by inductively coupled plasma-atomic emission spectroscopy

International Nuclear Information System (INIS)

Mahanti, H.S.; Barnes, R.M.

1983-01-01

Inductively coupled plasma-atomic emission spectroscopy is evaluated for the determination of 14 rare earth elements in aluminum. Spectral line interference, limit of detection, and background equivalent concentration values are evaluated, and quantitative recovery is obtained from aluminum samples spiked with rare earth elements. The procedure is simple and suitable for routine process control analysis. 20 references, 5 tables

Semiconductor Laser Multi-Spectral Sensing and Imaging

Directory of Open Access Journals (Sweden)

Han Q. Le

2010-01-01

Full Text Available Multi-spectral laser imaging is a technique that can offer a combination of the laser capability of accurate spectral sensing with the desirable features of passive multispectral imaging. The technique can be used for detection, discrimination, and identification of objects by their spectral signature. This article describes and reviews the development and evaluation of semiconductor multi-spectral laser imaging systems. Although the method is certainly not specific to any laser technology, the use of semiconductor lasers is significant with respect to practicality and affordability. More relevantly, semiconductor lasers have their own characteristics; they offer excellent wavelength diversity but usually with modest power. Thus, system design and engineering issues are analyzed for approaches and trade-offs that can make the best use of semiconductor laser capabilities in multispectral imaging. A few systems were developed and the technique was tested and evaluated on a variety of natural and man-made objects. It was shown capable of high spectral resolution imaging which, unlike non-imaging point sensing, allows detecting and discriminating objects of interest even without a priori spectroscopic knowledge of the targets. Examples include material and chemical discrimination. It was also shown capable of dealing with the complexity of interpreting diffuse scattered spectral images and produced results that could otherwise be ambiguous with conventional imaging. Examples with glucose and spectral imaging of drug pills were discussed. Lastly, the technique was shown with conventional laser spectroscopy such as wavelength modulation spectroscopy to image a gas (CO. These results suggest the versatility and power of multi-spectral laser imaging, which can be practical with the use of semiconductor lasers.

Semiconductor laser multi-spectral sensing and imaging.

Science.gov (United States)

Le, Han Q; Wang, Yang

2010-01-01

Multi-spectral laser imaging is a technique that can offer a combination of the laser capability of accurate spectral sensing with the desirable features of passive multispectral imaging. The technique can be used for detection, discrimination, and identification of objects by their spectral signature. This article describes and reviews the development and evaluation of semiconductor multi-spectral laser imaging systems. Although the method is certainly not specific to any laser technology, the use of semiconductor lasers is significant with respect to practicality and affordability. More relevantly, semiconductor lasers have their own characteristics; they offer excellent wavelength diversity but usually with modest power. Thus, system design and engineering issues are analyzed for approaches and trade-offs that can make the best use of semiconductor laser capabilities in multispectral imaging. A few systems were developed and the technique was tested and evaluated on a variety of natural and man-made objects. It was shown capable of high spectral resolution imaging which, unlike non-imaging point sensing, allows detecting and discriminating objects of interest even without a priori spectroscopic knowledge of the targets. Examples include material and chemical discrimination. It was also shown capable of dealing with the complexity of interpreting diffuse scattered spectral images and produced results that could otherwise be ambiguous with conventional imaging. Examples with glucose and spectral imaging of drug pills were discussed. Lastly, the technique was shown with conventional laser spectroscopy such as wavelength modulation spectroscopy to image a gas (CO). These results suggest the versatility and power of multi-spectral laser imaging, which can be practical with the use of semiconductor lasers.

Magneto-optical transmission-reflection beam splitter for multi-level atoms

International Nuclear Information System (INIS)

Murphy, J.E.; Goodman, P.; Sidorov, A.I.

1994-01-01

An atomic de Broglie wave beam splitter is proposed. The interaction of multi-level atoms (J g = 1 - J e = 0) with a laser beam in the presence of a static magnetic field leads to the partial transmission and reflection of the atomic beam. The coherent splitting of the atomic beam occurs due to non-adiabatic transitions between different dressed states in the vicinity of avoided crossings. The transition probabilities and populations of split beams are dependent on the value of the magnetic field, laser detuning, and the ratio between different polarization components in the laser beam. For optimal conditions the population of each of the two transmitted and two reflected beams is 25 per cent. For cooled atoms it is possible to obtain splitting angles of 80 mrad. The effect of spontaneous emission during the atom-light interaction was estimated and for a reasonable detuning losses were reduced to less than 10 per cent. 14 refs., 1 tab., 6 figs

Flame emission, atomic absorption and fluorescence spectrometry

International Nuclear Information System (INIS)

Horlick, G.

1980-01-01

Six hundred and thirty references are cited in this review. The information in the review is divided into 12 major areas: books, reviews, and bibliographies; fundamental studies in flames; developments in instrumentation; measurement techniques and procedure; flame emission spectrometry; flame atomic absorption spectrometry; flame molecular absorption spectrometry; electrothermal atomization atomic absorption spectroscopy; hydride generation techniques; graphite furnace atomic emission spectrometry; atomic fluorescence spectrometry; and analytical comparisons

Improved documentation of spectral lines for inductively coupled plasma emission spectrometry

Science.gov (United States)

Doidge, Peter S.

2018-05-01

An approach to improving the documentation of weak spectral lines falling near the prominent analytical lines used in inductively coupled plasma optical emission spectrometry (ICP-OES) is described. Measurements of ICP emission spectra in the regions around several hundred prominent lines, using concentrated solutions (up to 1% w/v) of some 70 elements, and comparison of the observed spectra with both recent published work and with the output of a computer program that allows calculation of transitions between the known energy levels, show that major improvements can be made in the coverage of spectral atlases for ICP-OES, with respect to "classical" line tables. It is argued that the atomic spectral data (wavelengths, energy levels) required for the reliable identification and documentation of a large majority of the weak interfering lines of the elements detectable by ICP-OES now exist, except for most of the observed lines of the lanthanide elements. In support of this argument, examples are provided from a detailed analysis of a spectral window centered on the prominent Pb II 220.353 nm line, and from a selected line-rich spectrum (W). Shortcomings in existing analyses are illustrated with reference to selected spectral interferences due to Zr. This approach has been used to expand the spectral-line library used in commercial ICP-ES instruments (Agilent 700-ES/5100-ES). The precision of wavelength measurements is evaluated in terms of the shot-noise limit, while the absolute accuracy of wavelength measurement is characterised through comparison with a small set of precise Ritz wavelengths for Sb I, and illustrated through the identification of Zr III lines; it is further shown that fractional-pixel absolute wavelength accuracies can be achieved. Finally, problems with the wavelengths and classifications of certain Au I lines are discussed.

First-principles dynamics treatment of light emission in collisions between alkali-metal atom and noble-gas atom collisions at 10keV

Science.gov (United States)

Pacheco, Alexander B.; Reyes, Andrés; Micha, David A.

2006-12-01

Collision-induced light emission during the interaction of an alkali-metal atom and a noble-gas atom is treated within a first-principles, or direct, dynamics approach that calculates a time-dependent electric dipole for the whole system, and spectral emission cross sections from its Fourier transform. These cross sections are very sensitive to excited diatomic potentials and a source of information on their shape. The coupling between electronic transitions and nuclear motions is treated with atomic pseudopotentials and an electronic density matrix coupled to trajectories for the nuclei. A recently implemented pseudopotential parametrization scheme is used here for the ground and excited states of the LiHe system, and to calculate state-to-state dipole moments. To verify the accuracy of our new parameters, we recalculate the integral cross sections for the LiHe system in the keV energy regime and obtain agreement with other results from theory and experiment. We further present results for the emission spectrum from 10keV Li(2s)+He collisions, and compare them to experimental values available in the region of light emitted at 300-900nm .

The Multi-component X-ray Emission of 3C 273

Science.gov (United States)

Soldi, S.; Türler, M.; Paltani, S.; Courvoisier, T. J.-L.

2009-05-01

3C 273 is the brightest quasar in the sky and among the most extensively observed and studied AGN, therefore one of the most suitable targets for a long-term, multi-frequency study. The superposition of a thermal Comptonisation component, similar to that observed in Seyfert galaxies, and of a non-thermal component, related to the jet emission, seems to explain some of the spectral and timing properties of the X-ray emission of 3C 273. Yet, during some observations this dichotomy has not been observed and the variability properties could also be consistent with a single-component scenario, characterised by two parameters varying independently. In order to understand the nature of the X-ray emission in 3C 273, a series of observations up to 80-100 keV, possibly catching the source in different flux states, are essential. Simbol-X will be able to study the emission of 3C 273 in the broad 0.5-80 keV band with high sensitivity, allowing us to disentangle the emission from different spectral components, with 20-30 ks long observations. In addition, the shape and the origin of the high-energy emission of this quasar will be further constrained thanks to the AGILE and Fermi satellites, monitoring the γ-ray sky in the MeV-GeV energy domain.

Multi-spectral pyrometer for gas turbine blade temperature measurement

Science.gov (United States)

Gao, Shan; Wang, Lixin; Feng, Chi

2014-09-01

To achieve the highest possible turbine inlet temperature requires to accurately measuring the turbine blade temperature. If the temperature of blade frequent beyond the design limits, it will seriously reduce the service life. The problem for the accuracy of the temperature measurement includes the value of the target surface emissivity is unknown and the emissivity model is variability and the thermal radiation of the high temperature environment. In this paper, the multi-spectral pyrometer is designed provided mainly for range 500-1000°, and present a model corrected in terms of the error due to the reflected radiation only base on the turbine geometry and the physical properties of the material. Under different working conditions, the method can reduce the measurement error from the reflect radiation of vanes, make measurement closer to the actual temperature of the blade and calculating the corresponding model through genetic algorithm. The experiment shows that this method has higher accuracy measurements.

Chemical Analysis of Impurity Boron Atoms in Diamond Using Soft X-ray Emission Spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Muramatsu, Yasuji; Iihara, Junji; Takebe, Toshihiko; Denlinger, Jonathan D.

2008-03-29

To analyze the local structure and/or chemical states of boron atoms in boron-doped diamond, which can be synthesized by the microwave plasma-assisted chemical vapor deposition method (CVD-B-diamond) and the temperature gradient method at high pressure and high temperature (HPT-B-diamond), we measured the soft X-ray emission spectra in the CK and BK regions of B-diamonds using synchrotron radiation at the Advanced Light Source (ALS). X-ray spectral analyses using the fingerprint method and molecular orbital calculations confirm that boron atoms in CVD-B-diamond substitute for carbon atoms in the diamond lattice to form covalent B-C bonds, while boron atoms in HPT-B-diamond react with the impurity nitrogen atoms to form hexagonal boron nitride. This suggests that the high purity diamond without nitrogen impurities is necessary to synthesize p-type B-diamond semiconductors.

A Spectral Emissivity Library of Spoil Substrates

Czech Academy of Sciences Publication Activity Database

Pivovarník, Marek; Pikl, Miroslav; Frouz, J.; Zemek, František; Kopačková, V.; Notesco, G.; Ben Dor, E.

2016-01-01

Roč. 1, č. 2 (2016) E-ISSN 2306-5729 R&D Projects: GA MŠk(CZ) LO1415 Institutional support: RVO:86652079 Keywords : post-mining sites * spectral emissivity * spectral library * spoil substrates Subject RIV: EH - Ecology, Behaviour OBOR OECD: Environmental sciences (social aspects to be 5.7)

Multi-wavelength emission from 3C 66A: clues to its redshift and gamma-ray emission location

International Nuclear Information System (INIS)

Yan Da-Hai; Fan Zhong-Hui; Zhou Yao; Dai Ben-Zhong

2013-01-01

The quasi-simultaneous multi-wavelength emission of TeV blazar 3C 66A is studied by using a one-zone multi-component leptonic jet model. It is found that the quasi-simultaneous spectral energy distribution of 3C 66A can be well reproduced; in particular, the first three months of its average Fermi-LAT spectrum can be well reproduced by the synchrotron self-Compton component plus external Compton component of the broad line region (BLR). Clues to its redshift and gamma-ray emission location are obtained. The results indicate the following. (i) On the redshift: The theoretical intrinsic TeV spectra can be predicted by extrapolating the reproduced GeV spectra. Through comparing these extrapolated TeV spectra with the corrected observed TeV spectra from extragalactic background light, it is suggested that the redshift of 3C 66A could be between 0.1 and 0.3, with the most likely value being ∼ 0.2. (ii) On the gamma-ray emission location: To well reproduce the GeV emission of 3C 66A under different assumptions on the BLR, the gamma-ray emission region is always required to be beyond the inner zone of the BLR. The BLR absorption effect on gamma-ray emission confirms this point.

Determination of heavy metals in solid emission and immission samples using atomic absorption spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Fara, M.; Novak, F. [EGU Prague, PLC, Bichovice, Prague (Czechoslovakia)

1995-12-01

Both flame and electrothermal methods of atomic absorption spectroscopy (AAS) have been applied to the determination of Al, As, Be, Ca, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, TI, Se, V and Zn in emission and emission (deposition) samples decomposed in open PTFE test-tubes by individual fuming-off hydrofluoric, perchloroic and nitric acid. An alternative hydride technique was also used for As and Se determination and Hg was determined using a self-contained AAS analyzer. A graphite platform proved good to overcome non-spectral interferences in AAS-ETA. Methods developed were verified by reference materials (inc. NBS 1633a).

Atom localization via controlled spontaneous emission in a five-level atomic system

International Nuclear Information System (INIS)

Wang Zhiping; Yu Benli; Zhu Jun; Cao Zhigang; Zhen Shenglai; Wu Xuqiang; Xu Feng

2012-01-01

We investigate the one- and two-dimensional atom localization behaviors via spontaneous emission in a coherently driven five-level atomic system by means of a radio-frequency field driving a hyperfine transition. It is found that the detecting probability and precision of atom localization behaviors can be significantly improved via adjusting the system parameters. More importantly, the two-dimensional atom localization patterns reveal that the maximal probability of finding an atom within the sub-wavelength domain of the standing waves can reach unity when the corresponding conditions are satisfied. As a result, our scheme may be helpful in laser cooling or the atom nano-lithography via atom localization. - Highlights: ► One- and two-dimensional atom localization behaviors via spontaneous emission in five-level atoms are investigated. ► An assisting radio-frequency field is used to control the atom localization behaviors. ► High-precision and high-resolution two-dimensional atom localization can be realized in this scheme.

Exploiting physical constraints for multi-spectral exo-planet detection

Science.gov (United States)

Thiébaut, Éric; Devaney, Nicholas; Langlois, Maud; Hanley, Kenneth

2016-07-01

We derive a physical model of the on-axis PSF for a high contrast imaging system such as GPI or SPHERE. This model is based on a multi-spectral Taylor series expansion of the diffraction pattern and predicts that the speckles should be a combination of spatial modes with deterministic chromatic magnification and weighting. We propose to remove most of the residuals by fitting this model on a set of images at multiple wavelengths and times. On simulated data, we demonstrate that our approach achieves very good speckle suppression without additional heuristic parameters. The residual speckles1, 2 set the most serious limitation in the detection of exo-planets in high contrast coronographic images provided by instruments such as SPHERE3 at the VLT, GPI4, 5 at Gemini, or SCExAO6 at Subaru. A number of post-processing methods have been proposed to remove as much as possible of the residual speckles while preserving the signal from the planets. These methods exploit the fact that the speckles and the planetary signal have different temporal and spectral behaviors. Some methods like LOCI7 are based on angular differential imaging8 (ADI), spectral differential imaging9, 10 (SDI), or on a combination of ADI and SDI.11 Instead of working on image differences, we propose to tackle the exo-planet detection as an inverse problem where a model of the residual speckles is fit on the set of multi-spectral images and, possibly, multiple exposures. In order to reduce the number of degrees of freedom, we impose specific constraints on the spatio-spectral distribution of stellar speckles. These constraints are deduced from a multi-spectral Taylor series expansion of the diffraction pattern for an on-axis source which implies that the speckles are a combination of spatial modes with deterministic chromatic magnification and weighting. Using simulated data, the efficiency of speckle removal by fitting the proposed multi-spectral model is compared to the result of using an approximation

Multi-quantum excitation in optically pumped alkali atom: rare gas mixtures

Science.gov (United States)

Galbally-Kinney, K. L.; Rawlins, W. T.; Davis, S. J.

2014-03-01

Diode-pumped alkali laser (DPAL) technology offers a means of achieving high-energy gas laser output through optical pumping of the D-lines of Cs, Rb, and K. The exciplex effect, based on weak attractive forces between alkali atoms and polarizable rare gas atoms (Ar, Kr, Xe), provides an alternative approach via broadband excitation of exciplex precursors (XPAL). In XPAL configurations, we have observed multi-quantum excitation within the alkali manifolds which result in infrared emission lines between 1 and 4 μm. The observed excited states include the 42FJ states of both Cs and Rb, which are well above the two-photon energy of the excitation laser in each case. We have observed fluorescence from multi-quantum states for excitation wavelengths throughout the exciplex absorption bands of Cs-Ar, Cs-Kr, and Cs-Xe. The intensity scaling is roughly first-order or less in both pump power and alkali concentration, suggesting a collisional energy pooling excitation mechanism. Collisional up-pumping appears to present a parasitic loss term for optically pumped atomic systems at high intensities, however there may also be excitation of other lasing transitions at infrared wavelengths.

Proton and electron impact on molecular and atomic oxygen: I. High resolution fluorescence spectra in the visible and VUV spectral range and emission cross-sections for dissociative ionisation and excitation of O2

International Nuclear Information System (INIS)

Wilhelmi, O.; Schartner, K.H.

2000-01-01

For pt.II see ibid., vol.11, p.45-58, 2000. Molecular oxygen O 2 was dissociated in collisions with protons and electrons in the intermediate velocity range (p + -energies: 17-800 keV, e - -energies: 0.2-2 keV). Fluorescence from excited atomic and singly ionised fragments and from singly ionised molecules was detected in the VUV and in the visible and near UV spectral range. Highly resolved spectra are presented for the VUV (46-131 nm) and the near UV/visible (340-605 nm) spectral range. Absolute emission cross-sections have been determined for dissociative ionisation and excitation leading to fluorescence in the VUV. Results are compared with published data. (orig.)

The Effect of Substrate Emissivity on the Spectral Emission of a Hot-Gas Overlayer

Science.gov (United States)

2015-12-30

The spectral radiosity , denoted by Js(0, λ, Ts, Tsurf) accounts for both the emitted spectral energy and the reflected spectral energy from the...spectral intensity emitted from the window is given by I(λ, Twin) = εwinI(λ, Twin)BB where εwin is the spectral emissivity. The spectral radiosity incident... radiosity , one determines that the window contributes 6.1% reflected radiation to the observed signal from the anode. Figure 9. Anode-Window Geometry

The use of double laser pulses for the atomic-emission spectral estimation of uranium content in biological samples

International Nuclear Information System (INIS)

Patapovich, M.P.; Umreiko, D.S.; Zajogin, A.P.; Buloichik, J.I.

2012-01-01

This paper is aimed at the development of the techniques for estimation of the uranium content in biological objects (hair) using the atomic-emission laser analysis with a sufficient accuracy and high processing rate. (authors)

Removal of Optically Thick Clouds from Multi-Spectral Satellite Images Using Multi-Frequency SAR Data

Directory of Open Access Journals (Sweden)

Robert Eckardt

2013-06-01

Full Text Available This study presents a method for the reconstruction of pixels contaminated by optical thick clouds in multi-spectral Landsat images using multi-frequency SAR data. A number of reconstruction techniques have already been proposed in the scientific literature. However, all of the existing techniques have certain limitations. In order to overcome these limitations, we expose the Closest Spectral Fit (CSF method proposed by Meng et al. to a new, synergistic approach using optical and SAR data. Therefore, the term Closest Feature Vector (CFV is introduced. The technique facilitates an elegant way to avoid radiometric distortions in the course of image reconstruction. Furthermore the cloud cover removal is independent from underlying land cover types and assumptions on seasonality, etc. The methodology is applied to mono-temporal, multi-frequency SAR data from TerraSAR-X (X-Band, ERS (C-Band and ALOS Palsar (L-Band. This represents a way of thinking about Radar data not as foreign, but as additional data source in multi-spectral remote sensing. For the assessment of the image restoration performance, an experimental framework is established and a statistical evaluation protocol is designed. The results show the potential of a synergistic usage of multi-spectral and SAR data to overcome the loss of data due to cloud cover.

Multi-layer composite structure covered polytetrafluoroethylene for visible-infrared-radar spectral Compatibility

Science.gov (United States)

Qi, Dong; Cheng, Yongzhi; Wang, Xian; Wang, Fang; Li, Bowen; Gong, Rongzhou

2017-12-01

In this paper, a polytetrafluoroethylene (PTFE) top-covered multi-layer composite structure PTFE/H s/(Ge/ZnS)3 (H s represents the surface layer ZnS with various thicknesses) for spectral compatibility is proposed and investigated theoretically and experimentally. A substantial decline of glossiness from over 200 Gs to 74.2 Gs could be realized, due to high roughness and interface reflection of the 800 nm PTFE protection layer. In addition, similar to the structure of H s/(Ge/ZnS)3, the designed structure with a certain color exhibits ultra-low emissivity of average 0.196 at 8-14 µm and highly transparent performance of 96.45% in the radar frequency range of 2-18 GHz. Our design will provide an important reference for the practical applications of the spectral compatible multilayer films.

A Cost Effective Multi-Spectral Scanner for Natural Gas Detection

Energy Technology Data Exchange (ETDEWEB)

Yudaya Sivathanu; Jongmook Lim; Vinoo Narayanan; Seonghyeon Park

2005-12-07

The objective of this project is to design, fabricate and demonstrate a cost effective, multi-spectral scanner for natural gas leak detection in transmission and distribution pipelines. During the first year of the project, a laboratory version of the multi-spectral scanner was designed, fabricated, and tested at EnUrga Inc. The multi-spectral scanner was also evaluated using a blind Department of Energy study at the Rocky Mountain Oilfield Testing Center. The performance of the scanner was inconsistent during the blind study. However, most of the leaks were outside the view of the multi-spectral scanner that was developed during the first year of the project. Therefore, a definite evaluation of the capability of the scanner was not obtained. Despite the results, sufficient number of plumes was detected fully confirming the feasibility of the multi-spectral scanner. During the second year, the optical design of the scanner was changed to improve the sensitivity of the system. Laboratory tests show that the system can reliably detect small leaks (20 SCFH) at 30 to 50 feet. A prototype scanner was built and evaluated during the second year of the project. Only laboratory evaluations were completed during the second year. The laboratory evaluations show the feasibility of using the scanner to determine natural gas pipeline leaks. Further field evaluations and optimization of the scanner are required before commercialization of the scanner can be initiated.

On- and off-axis spectral emission features from laser-produced gas breakdown plasmas

Energy Technology Data Exchange (ETDEWEB)

Harilal, S. S.; Skrodzki, P. J.; Miloshevsky, A.; Brumfield, B. E.; Phillips, M. C.; Miloshevsky, G.

2017-06-01

Laser-heated gas breakdown plasmas or sparks emit profoundly in the ultraviolet and visible region of the electromagnetic spectrum with contributions from ionic, atomic, and molecular species. Laser created kernels expand into a cold ambient with high velocities during its early lifetime followed by confinement of the plasma kernel and eventually collapse. However, the plasma kernels produced during laser breakdown of gases are also capable of exciting and ionizing the surrounding ambient medium. Two mechanisms can be responsible for excitation and ionization of surrounding ambient: viz. photoexcitation and ionization by intense ultraviolet emission from the sparks produced during the early times of its creation and/or heating by strong shocks generated by the kernel during its expansion into the ambient. In this study, an investigation is made on the spectral features of on- and off-axis emission features of laser-induced plasma breakdown kernels generated in atmospheric pressure conditions with an aim to elucidate the mechanisms leading to ambient excitation and emission. Pulses from an Nd:YAG laser emitting at 1064 nm with 6 ns pulse duration are used to generate plasma kernels. Laser sparks were generated in air, argon, and helium gases to provide different physical properties of expansion dynamics and plasma chemistry considering the differences in laser absorption properties, mass density and speciation. Point shadowgraphy and time-resolved imaging were used to evaluate the shock wave and spark self-emission morphology at early and late times while space and time resolved spectroscopy is used for evaluating the emission features as well as for inferring plasma fundaments at on- and off-axis. Structure and dynamics of the plasma kernel obtained using imaging techniques are also compared to numerical simulations using computational fluid dynamics code. The emission from the kernel showed that spectral features from ions, atoms and molecules are separated in

Multi-spectral endogenous fluorescence imaging for bacterial differentiation

Science.gov (United States)

Chernomyrdin, Nikita V.; Babayants, Margarita V.; Korotkov, Oleg V.; Kudrin, Konstantin G.; Rimskaya, Elena N.; Shikunova, Irina A.; Kurlov, Vladimir N.; Cherkasova, Olga P.; Komandin, Gennady A.; Reshetov, Igor V.; Zaytsev, Kirill I.

2017-07-01

In this paper, the multi-spectral endogenous fluorescence imaging was implemented for bacterial differentiation. The fluorescence imaging was performed using a digital camera equipped with a set of visual bandpass filters. Narrowband 365 nm ultraviolet radiation passed through a beam homogenizer was used to excite the sample fluorescence. In order to increase a signal-to-noise ratio and suppress a non-fluorescence background in images, the intensity of the UV excitation was modulated using a mechanical chopper. The principal components were introduced for differentiating the samples of bacteria based on the multi-spectral endogenous fluorescence images.

CHIANTI—AN ATOMIC DATABASE FOR EMISSION LINES. XII. VERSION 7 OF THE DATABASE

International Nuclear Information System (INIS)

Landi, E.; Del Zanna, G.; Mason, H. E.; Young, P. R.; Dere, K. P.

2012-01-01

The CHIANTI spectral code consists of an atomic database and a suite of computer programs to calculate the optically thin spectrum of astrophysical objects and carry out spectroscopic plasma diagnostics. The database includes atomic energy levels, wavelengths, radiative transition probabilities, collision excitation rate coefficients, and ionization and recombination rate coefficients, as well as data to calculate free-free, free-bound, and two-photon continuum emission. Version 7 has been released, which includes several new ions, significant updates to existing ions, as well as Chianti-Py, the implementation of CHIANTI software in the Python programming language. All data and programs are freely available at http://www.chiantidatabase.org, while the Python interface to CHIANTI can be found at http://chiantipy.sourceforge.net.

CHIANTI-AN ATOMIC DATABASE FOR EMISSION LINES. XII. VERSION 7 OF THE DATABASE

Energy Technology Data Exchange (ETDEWEB)

Landi, E. [Department of Atmospheric, Oceanic and Space Sciences, University of Michigan, Ann Arbor, MI 48109 (United States); Del Zanna, G.; Mason, H. E. [Department of Applied Mathematics and Theoretical Physics, University of Cambridge, Wilberforce Road, Cambridge CB3 0WA (United Kingdom); Young, P. R. [College of Science, George Mason University, 4400 University Drive, Fairfax, VA, 22030 (United States); Dere, K. P. [School of Physics, Astronomy and Computational Sciences, MS 6A2, George Mason University, 4400 University Drive, Fairfax, VA 22030 (United States)

2012-01-10

The CHIANTI spectral code consists of an atomic database and a suite of computer programs to calculate the optically thin spectrum of astrophysical objects and carry out spectroscopic plasma diagnostics. The database includes atomic energy levels, wavelengths, radiative transition probabilities, collision excitation rate coefficients, and ionization and recombination rate coefficients, as well as data to calculate free-free, free-bound, and two-photon continuum emission. Version 7 has been released, which includes several new ions, significant updates to existing ions, as well as Chianti-Py, the implementation of CHIANTI software in the Python programming language. All data and programs are freely available at http://www.chiantidatabase.org, while the Python interface to CHIANTI can be found at http://chiantipy.sourceforge.net.

Quantum state preparation using multi-level-atom optics

International Nuclear Information System (INIS)

Busch, Th; Deasy, K; Chormaic, S Nic

2007-01-01

One of the most important characteristics for controlling processes on the quantum scale is the fidelity or robustness of the techniques being used. In the case of single atoms localized in micro-traps, it was recently shown that the use of time-dependent tunnelling interactions in a multi-trap setup can be viewed as analogous to the area of multi-level optics. The atom's centre-of-mass can then be controlled with a high fidelity, using a STIRAP-type process. Here, we review previous work that led to the development of multi-level atom optics and present two examples of our most recent work on quantum state preparation

Spectral emissivity of surface blackbody calibrators

DEFF Research Database (Denmark)

Clausen, Sønnik

2007-01-01

The normal spectral emissivity of commercial infrared calibrators is compared with measurements of anodized aluminum samples and grooved aluminum surfaces coated with Pyromark. Measurements performed by FTIR spectroscopy in the wavelength interval from 2 to 20 mu m and at temperatures between 5...

Atomic structure calculations and identification of EUV and SXR spectral lines in Sr XXX

International Nuclear Information System (INIS)

Goyal, Arun; Khatri, Indu; Aggarwal, Sunny; Singh, A.K.; Mohan, Man

2015-01-01

We report an extensive theoretical study of atomic data for Sr XXX in a wide range with L-shell electron excitations to the M-shell. We have calculated energy levels, wave-function compositions and lifetimes for lowest 113 fine structure levels and wavelengths of an extreme Ultraviolet (EUV) and soft X-ray (SXR) transitions. We have employed multi-configuration Dirac Fock method (MCDF) approach within the framework of Dirac–Coulomb Hamiltonian including quantum electrodynamics (QED) and Breit corrections. We have also presented the radiative data for electric and magnetic dipole (E1, M1) and quadrupole (E2, M2) transitions from the ground state. We have made comparisons with available energy levels compiled by NIST and achieve good agreement. But due to inadequate data in the literature, analogous relativistic distorted wave calculations have also been performed using flexible atomic code (FAC) to assess the reliability and accuracy of our results. Additionally, we have provided new atomic data for Sr XXX which is not published elsewhere in the literature and we believe that our results may be beneficial in fusion plasma research and astrophysical investigations and applications. - Highlights: • 113 Lowest levels for Sr XXX are calculated. • Extreme Ultraviolet (EUV) and soft-X ray (SXR) spectral lines are identified. • Wavelengths of EUV and SXR spectral lines are reported. • E1, E2, M1 and M2 transition rates, oscillator strengths and lines strengths for lowest 113 levels are presented. • Lifetimes for lowest 113 fine structure levels are provided

Pyrolysis gas chromatographic atomic emission detection for sediments, coals and other petrochemical precursors

Energy Technology Data Exchange (ETDEWEB)

Seeley, J.A.; Zeng, Y.D.; Uden, P.C.; Eglinton, T.I.; Ericson, I. (Massachusetts University, Amherst, MA (USA). Dept. of Chemistry)

1992-09-01

On-line flash pyrolysis coupled to a capillary gas chromatograph for the characterization of marine sediments, coals and other heterogeneous solid samples is described. A helium microwave-induced plasma is used for chromatographic detection by atomic emission spectrometry. Simultaneous multi-element detection is achieved with a photodiode array detector. The optical path of the gas chromatographic atomic emission detector is purged with helium, allowing simultaneous, sensitive detection of atomic emission from sulfur 181 nm, phosphorous 186 nm, arsenic 189 nm, selenium 196 nm and carbon 193 nm. Several sediment and coal samples have been analysed for their carbon, nitrogen, sulfur, oxygen, phosphorous, arsenic and selenium content. Qualitative information indicating the occurrence and distribution of these elements in the samples can be used to gauge the relative stage of diagenetic evolution of the samples and provide information on their depositional environment. In some instances the chromatographic behaviour of the compounds produced upon pyrolysis is improved through on-line alkylation. This on-line derivatization is achieved by adding liquid reagents to the pyrolysis probe or by adding liquid reagents to the pyrolysis probe or by adding solid reagents either to the solid sample or by packing the reagent in the injection port of the chromatograph.

Metastable argon atom density in complex argon/acetylene plasmas determined by means of optical absorption and emission spectroscopy

International Nuclear Information System (INIS)

Sushkov, Vladimir; Herrendorf, Ann-Pierra; Hippler, Rainer

2016-01-01

Optical emission and absorption spectroscopy has been utilized to investigate the instability of acetylene-containing dusty plasmas induced by growing nano-particles. The density of Ar(1s 5 ) metastable atoms was derived by two methods: tunable diode laser absorption spectroscopy and with the help of the branching ratio method of emitted spectral lines. Results of the two techniques agree well with each other. The density of Ar(1s 3 ) metastable atoms was also measured by means of optical emission spectroscopy. The observed growth instability leads to pronounced temporal variations of the metastable and other excited state densities. An analysis of optical line ratios provides evidence for a depletion of free electrons during the growth cycle but no indication for electron temperature variations. (paper)

Spectral emission from the alkali inductively-coupled plasma: Theory and experiment

Directory of Open Access Journals (Sweden)

R. Bazurto

2018-04-01

Full Text Available The weakly-ionized, alkali inductively-coupled plasma (ICP has a long history as the light source for optical pumping. Today, its most significant application is perhaps in the rubidium atomic frequency standard (RAFS, arguably the workhorse of atomic timekeeping in space, where it is crucial to the RAFS’ functioning and performance (and routinely referred to as the RAFS’ “rf-discharge lamp”. In particular, the photon flux from the lamp determines the signal-to-noise ratio of the device, and variations in ICP brightness define the long-term frequency stability of the atomic clock as a consequence of the ac-Stark shift (i.e., the light-shift. Given the importance of Rb atomic clocks to diverse satellite navigation systems (e.g., GPS, Galileo, BeiDou – and thereby the importance of alkali ICPs to these systems – it is somewhat surprising to find that the physical processes occurring within the discharge are not well understood. As a consequence, researchers do not understand how to improve the spectral emission from the lamp except at a trial-and-error level, nor do they fully understand the nonlinear mechanisms that result in ICP light instability. Here, we take a first step in developing an intuitive, semi-quantitative model of the alkali rf-discharge lamp, and we perform a series of experiments to validate the theory’s predictions.

Spectral emission from the alkali inductively-coupled plasma: Theory and experiment

Science.gov (United States)

Bazurto, R.; Huang, M.; Camparo, J.

2018-04-01

The weakly-ionized, alkali inductively-coupled plasma (ICP) has a long history as the light source for optical pumping. Today, its most significant application is perhaps in the rubidium atomic frequency standard (RAFS), arguably the workhorse of atomic timekeeping in space, where it is crucial to the RAFS' functioning and performance (and routinely referred to as the RAFS' "rf-discharge lamp"). In particular, the photon flux from the lamp determines the signal-to-noise ratio of the device, and variations in ICP brightness define the long-term frequency stability of the atomic clock as a consequence of the ac-Stark shift (i.e., the light-shift). Given the importance of Rb atomic clocks to diverse satellite navigation systems (e.g., GPS, Galileo, BeiDou) - and thereby the importance of alkali ICPs to these systems - it is somewhat surprising to find that the physical processes occurring within the discharge are not well understood. As a consequence, researchers do not understand how to improve the spectral emission from the lamp except at a trial-and-error level, nor do they fully understand the nonlinear mechanisms that result in ICP light instability. Here, we take a first step in developing an intuitive, semi-quantitative model of the alkali rf-discharge lamp, and we perform a series of experiments to validate the theory's predictions.

Airborne Multi-Spectral Minefield Survey

Science.gov (United States)

2005-05-01

Swedish Defence Research Agency), GEOSPACE (Austria), GTD ( Ingenieria de Sistemas y Software Industrial, Spain), IMEC (Ineruniversity MicroElectronic...RTO-MP-SET-092 18 - 1 UNCLASSIFIED/UNLIMITED UNCLASSIFIED/UNLIMITED Airborne Multi-Spectral Minefield Survey Dirk-Jan de Lange, Eric den...actions is the severe lack of baseline information. To respond to this in a rapid way, cost-efficient data acquisition methods are a key issue. de

Spectral emissivity of tungsten: analytic expressions for the 340-nm to 2.6-μm spectral region

International Nuclear Information System (INIS)

Pon, R.M.; Hessler, J.P.

1984-01-01

To correct emission spectra a standard radiance source is often used to determine the spectral responsivity of the detection system. In the near-UV, visible, and near-IR spectral regions the most common radiance standard is a tungsten strip lamp calibrated by a standards laboratory. For day-to-day experiments where slightly less accuracy is acceptable, a less expensive uncalibrated lamp is useful. In this case, the radiant temperature T/sub r/ of the lamp is measured with an optical pyrometer, generally at a single wavelength such as 650 nm, and the source spectral radiance L(λ) is calculated from L(λ) = tau(λ)epsilon(λ,T)L/sub B/(λ,T). The transmittance of the source is tau(λ), the spectral emissivity is epsilon(λ,T), and L/sub B/(λ,T) is the spectral distribution of blackbody radiation, Planck's radiation law. To obtain the true temperature T, Wien's approximation is employed. To conveniently calibrate a system, especially one which utilizes a microcomputer, it is advantageous to have analytic expressions for the spectral emissivity of tungsten. Although Larrabee has published such expressions, they are limited to the 450-800-nm spectral region. To obtain analytic expressions from 340 nm to 2.6 μm they have used the measurements of DeVos. Although DeVos's results differ by 2% from those of Larrabee, this difference is assumed to be acceptable

Plasma-related matrix effects in inductively coupled plasma--atomic emission spectrometry by group I and group II matrix-elements

International Nuclear Information System (INIS)

Chan, George C.-Y.; Chan, W.-T.

2003-01-01

The effects of Na, K, Ca and Ba matrices on the plasma excitation conditions in inductively coupled plasma-atomic emission spectrometry (ICP-AES) were studied. Normalized relative intensity was used to indicate the extent of the plasma-related matrix effects. The group I matrices have no effects on the plasma excitation conditions. In contrast, the group II matrices depress the normalized relative intensities of some spectral lines. Specifically, the Group II matrices have no effects on the normalized relative intensity of atomic lines of low upper energy level (soft lines), but reduce the normalized relative intensity of some ionic lines and atomic lines of high energy level (hard lines). The Group II matrices seem to shift the Saha balance of the analytes only; no shift in the Boltzmann balance was observed experimentally. Moreover, for some ionic lines with sum of ionization and excitation potentials close to the ionization potential of argon (15.75 eV), the matrix effect is smaller than other ionic lines of the same element. The reduced matrix effects may be attributed qualitatively to charge transfer excitation mechanism of these ionic lines. Charge transfer reaction renders ionic emission lines from the quasi-resonant levels similar in characteristics of atomic lines. The contribution of charge transfer relative to excitation by other non-specific excitation mechanisms (via Saha balance and Boltzmann balance) determines the degree of atomic behavior of a quasi-resonant level. A significant conclusion of this study is that plasma-related matrix effect depends strongly on the excitation mechanism of a spectral line. Since, in general, more than one excitation mechanism may contribute to the overall excitation of an emission line, the observed matrix effects reflect the sum of the effects due to individual excitation mechanisms. Excitation mechanisms, in addition to the often-used total excitation energy, should be considered in matrix effect studies

Swift captures the spectrally evolving prompt emission of GRB070616

Science.gov (United States)

Starling, R. L. C.; O'Brien, P. T.; Willingale, R.; Page, K. L.; Osborne, J. P.; de Pasquale, M.; Nakagawa, Y. E.; Kuin, N. P. M.; Onda, K.; Norris, J. P.; Ukwatta, T. N.; Kodaka, N.; Burrows, D. N.; Kennea, J. A.; Page, M. J.; Perri, M.; Markwardt, C. B.

2008-02-01

The origins of gamma-ray burst (GRB) prompt emission are currently not well understood and in this context long, well-observed events are particularly important to study. We present the case of GRB070616, analysing the exceptionally long-duration multipeaked prompt emission, and later afterglow, captured by all the instruments on-board Swift and by Suzaku Wide-Band All-Sky Monitor (WAM). The high-energy light curve remained generally flat for several hundred seconds before going into a steep decline. Spectral evolution from hard to soft is clearly taking place throughout the prompt emission, beginning at 285s after the trigger and extending to 1200s. We track the movement of the spectral peak energy, whilst observing a softening of the low-energy spectral slope. The steep decline in flux may be caused by a combination of this strong spectral evolution and the curvature effect. We investigate origins for the spectral evolution, ruling out a superposition of two power laws and considering instead an additional component dominant during the late prompt emission. We also discuss origins for the early optical emission and the physics of the afterglow. The case of GRB070616 clearly demonstrates that both broad-band coverage and good time resolution are crucial to pin down the origins of the complex prompt emission in GRBs. This paper is dedicated to the memory of Dr Francesca Tamburelli who died during its production. Francesca played a fundamental role within the team which is in charge of the development of the Swift X-Ray Telescope (XRT) data analysis software at the Italian Space Agency's Science Data Centre in Frascati. She is sadly missed. E-mail: rlcs1@star.le.ac.uk

Liquid-Arc/Spark-Excitation Atomic-Emission Spectroscopy

Science.gov (United States)

Schlagen, Kenneth J.

1992-01-01

Constituents of solutions identified in situ. Liquid-arc/spark-excitation atomic-emission spectroscopy (LAES) is experimental variant of atomic-emission spectroscopy in which electric arc or spark established in liquid and spectrum of light from arc or spark analyzed to identify chemical elements in liquid. Observations encourage development of LAES equipment for online monitoring of process streams in such industries as metal plating, electronics, and steel, and for online monitoring of streams affecting environment.

Emission spectrum of a harmonically trapped Λ-type three-level atom

International Nuclear Information System (INIS)

Guo Hong; Tang Pei

2013-01-01

We theoretically investigate the emission spectrum for a Λ-type three-level atom trapped in the node of a standing wave. We show that the atomic center-of-mass motion not only directly affects the peak number, peak position, and peak height in the atomic emission spectrum, but also influences the effects of the cavity field and the atomic initial state on atomic emission spectrum. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

Simultaneous Multi-Element Electrothermal Atomic Absorption ...

African Journals Online (AJOL)

NICO

and chemical interferences are associated with optimization of the light source and atomization programme and modification ... The following excerpts from the theory should help to estimate .... applicability of Equation (11) in practice depends on the spectral ..... The authors would like to acknowledge the National Research.

CHIANTI—AN ATOMIC DATABASE FOR EMISSION LINES. XIII. SOFT X-RAY IMPROVEMENTS AND OTHER CHANGES

International Nuclear Information System (INIS)

Landi, E.; Young, P. R.; Dere, K. P.; Del Zanna, G.; Mason, H. E.

2013-01-01

The CHIANTI spectral code consists of two parts: an atomic database and a suite of computer programs in Python and IDL. Together, they allow the calculation of the optically thin spectrum of astrophysical objects and provide spectroscopic plasma diagnostics for the analysis of astrophysical spectra. The database includes atomic energy levels, wavelengths, radiative transition probabilities, collision excitation rate coefficients, ionization, and recombination rate coefficients, as well as data to calculate free-free, free-bound, and two-photon continuum emission. Version 7.1 has been released, which includes improved data for several ions, recombination rates, and element abundances. In particular, it provides a large expansion of the CHIANTI models for key Fe ions from Fe VIII to Fe XIV to improve the predicted emission in the 50-170 Å wavelength range. All data and programs are freely available at http://www.chiantidatabase.org and in SolarSoft, while the Python interface to CHIANTI can be found at http://chiantipy.sourceforge.net.

Spectral tuning via multi-phonon-assisted stokes and anti-stokes excitations in LaF{sub 3}: Tm{sup 3+} nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Gao, Dangli, E-mail: gaodangli@163.com [School of Materials & Mineral Resources, Xi' an University of Architecture and Technology, Xi' an, Shaanxi 710055 (China); College of Science, Xi' an University of Architecture and Technology, Xi' an, Shaanxi 710055 (China); Shaanxi Key Laboratory of Nano Materials and Technology, Xi' an, Shaanxi 710055 (China); Tian, Dongping, E-mail: dptian@xauat.edu.cn [School of Materials & Mineral Resources, Xi' an University of Architecture and Technology, Xi' an, Shaanxi 710055 (China); College of Science, Xi' an University of Architecture and Technology, Xi' an, Shaanxi 710055 (China); Chong, Bo; Li, Long [College of Science, Xi' an University of Architecture and Technology, Xi' an, Shaanxi 710055 (China); Zhang, Xiangyu [College of Science, Chang' an University, Xi' an, Shaanxi 710064 (China)

2016-09-05

We present a facile and highly effective method to tailor upconversion (UC) emission from LaF{sub 3}: Tm{sup 3+} nanoparticles (NPs) by adjusting ambient temperature from 20 K to 400 K accompanied with the pulse laser excitation. Spectral tuning mechanism controlled by ambient temperature at pulse laser excitation is revealed, and a mechanism based on the modification on multi-phonon relaxation rates for the rapid population of intermediate level {sup 3}H{sub 4} and multi-phonon-assisted excited state absorption is proposed. Based on multi-phonon relaxation theory and time-resolved photoluminescence studies, it is reasonable that UC luminescence under short-pulse laser excitation mainly originates from the ions at/near the surface of NPs. These exciting findings in ambient temperature accompanied with the short-pulse excitation dependent UC selectivity offer a general approach to tailoring lanthanide related UC emissions, which will benefit multicolor displays and imaging. - Graphical abstract: An effective method to tailor upconversion from LaF{sub 3}: Tm{sup 3+} nanoparticles by adjusting ambient temperature accompanied with the short-pulse laser excitation is presented and the spectral tuning mechanism based the modification on multi-phonon relaxation rate and multi-phonon-assisted excited state absorption is also revealed. - Highlights: • The luminescence switching is controlled by temperature and pulse duration. • The mechanism based on the multi-phonon-assisted excitations is proposed. • Blue luminescence under short-pulse excitation originates from the surface ions. • Temperature has a big effect on luminescence color output.

LNG pool fire spectral data and calculation of emissive power

International Nuclear Information System (INIS)

Raj, Phani K.

2007-01-01

Spectral description of thermal emission from fires provides a fundamental basis on which the fire thermal radiation hazard assessment models can be developed. Several field experiments were conducted during the 1970s and 1980s to measure the thermal radiation field surrounding LNG fires. Most of these tests involved the measurement of fire thermal radiation to objects outside the fire envelope using either narrow-angle or wide-angle radiometers. Extrapolating the wide-angle radiometer data without understanding the nature of fire emission is prone to errors. Spectral emissions from LNG fires have been recorded in four test series conducted with LNG fires on different substrates and of different diameters. These include the AGA test series of LNG fires on land of diameters 1.8 and 6 m, 35 m diameter fire on an insulated concrete dike in the Montoir tests conducted by Gaz de France, a 1976 test with 13 m diameter and the 1980 tests with 10 m diameter LNG fire on water carried out at China Lake, CA. The spectral data from the Montoir test series have not been published in technical journals; only recently has some data from this series have become available. This paper presents the details of the LNG fire spectral data from, primarily, the China Lake test series, their analysis and results. Available data from other test series are also discussed. China Lake data indicate that the thermal radiation emission from 13 m diameter LNG fire is made up of band emissions of about 50% of energy by water vapor (band emission), about 25% by carbon dioxide and the remainder constituting the continuum emission by luminous soot. The emissions from the H 2 O and CO 2 bands are completely absorbed by the intervening atmosphere in less than about 200 m from the fire, even in the relatively dry desert air. The effective soot radiation constitutes only about 23% during the burning period of methane and increases slightly when other higher hydrocarbon species (ethane, propane, etc.) are

High performance multi-spectral interrogation for surface plasmon resonance imaging sensors.

Science.gov (United States)

Sereda, A; Moreau, J; Canva, M; Maillart, E

2014-04-15

Surface plasmon resonance (SPR) sensing has proven to be a valuable tool in the field of surface interactions characterization, especially for biomedical applications where label-free techniques are of particular interest. In order to approach the theoretical resolution limit, most SPR-based systems have turned to either angular or spectral interrogation modes, which both offer very accurate real-time measurements, but at the expense of the 2-dimensional imaging capability, therefore decreasing the data throughput. In this article, we show numerically and experimentally how to combine the multi-spectral interrogation technique with 2D-imaging, while finding an optimum in terms of resolution, accuracy, acquisition speed and reduction in data dispersion with respect to the classical reflectivity interrogation mode. This multi-spectral interrogation methodology is based on a robust five parameter fitting of the spectral reflectivity curve which enables monitoring of the reflectivity spectral shift with a resolution of the order of ten picometers, and using only five wavelength measurements per point. In fine, such multi-spectral based plasmonic imaging system allows biomolecular interaction monitoring in a linear regime independently of variations of buffer optical index, which is illustrated on a DNA-DNA model case. © 2013 Elsevier B.V. All rights reserved.

Qualitative tissue differentiation by analysing the intensity ratios of atomic emission lines using laser induced breakdown spectroscopy (LIBS): prospects for a feedback mechanism for surgical laser systems.

Science.gov (United States)

Kanawade, Rajesh; Mahari, Fanuel; Klämpfl, Florian; Rohde, Maximilian; Knipfer, Christian; Tangermann-Gerk, Katja; Adler, Werner; Schmidt, Michael; Stelzle, Florian

2015-01-01

The research work presented in this paper focuses on qualitative tissue differentiation by monitoring the intensity ratios of atomic emissions using 'Laser Induced Breakdown Spectroscopy' (LIBS) on the plasma plume created during laser tissue ablation. The background of this study is to establish a real time feedback control mechanism for clinical laser surgery systems during the laser ablation process. Ex-vivo domestic pig tissue samples (muscle, fat, nerve and skin) were used in this experiment. Atomic emission intensity ratios were analyzed to find a characteristic spectral line for each tissue. The results showed characteristic elemental emission intensity ratios for the respective tissues. The spectral lines and intensity ratios of these specific elements varied among the different tissue types. The main goal of this study is to qualitatively and precisely identify different tissue types for tissue specific laser surgery. © 2015 The Authors. Journal of Biophotonics published by WILEY-VCH Verlag.

Inductively coupled plasma as atomization, excitation and ionization sources in analytical atomic spectrometry

International Nuclear Information System (INIS)

Kawaguchi, Hiroshi

1996-01-01

Studies on inductively coupled plasma (ICP) for atomic emission and mass spectrometry accomplished in our laboratory since 1978 are reviewed. In emission spectrometry, the characteristics of the plasma are studied concerning the spatial profiles of spectral line intensity, axial profiles of gas and excitation temperatures, spectral line widths and matrix effect. The studies are particularly emphasized on the instrumentation such as developments of plasma generator, emission spectrometers, water-cooled torches and sample introduction methods. A slew-scan type spectrometer developed in these works represents a predecessor of the current commercial spectrometers. An ICP mass spectrometer was first developed in Japan in this laboratory in 1984. Non-spectroscopic interference of this method was found to have the correlation with the atomic weight of the matrix element. Plasma gases other than argon such as nitrogen and oxygen were used for the ICP to evaluate their performance in mass spectrometry as for the sensitivity and interferences. (author). 63 refs

Automated road network extraction from high spatial resolution multi-spectral imagery

Science.gov (United States)

Zhang, Qiaoping

For the last three decades, the Geomatics Engineering and Computer Science communities have considered automated road network extraction from remotely-sensed imagery to be a challenging and important research topic. The main objective of this research is to investigate the theory and methodology of automated feature extraction for image-based road database creation, refinement or updating, and to develop a series of algorithms for road network extraction from high resolution multi-spectral imagery. The proposed framework for road network extraction from multi-spectral imagery begins with an image segmentation using the k-means algorithm. This step mainly concerns the exploitation of the spectral information for feature extraction. The road cluster is automatically identified using a fuzzy classifier based on a set of predefined road surface membership functions. These membership functions are established based on the general spectral signature of road pavement materials and the corresponding normalized digital numbers on each multi-spectral band. Shape descriptors of the Angular Texture Signature are defined and used to reduce the misclassifications between roads and other spectrally similar objects (e.g., crop fields, parking lots, and buildings). An iterative and localized Radon transform is developed for the extraction of road centerlines from the classified images. The purpose of the transform is to accurately and completely detect the road centerlines. It is able to find short, long, and even curvilinear lines. The input image is partitioned into a set of subset images called road component images. An iterative Radon transform is locally applied to each road component image. At each iteration, road centerline segments are detected based on an accurate estimation of the line parameters and line widths. Three localization approaches are implemented and compared using qualitative and quantitative methods. Finally, the road centerline segments are grouped into a

Multilayer Photonic Crystal for Spectral Narrowing of Emission

Directory of Open Access Journals (Sweden)

Zhanfang LIU

2017-08-01

Full Text Available Multilayer colloidal crystal has been prepared by the layer-by-layer deposition of silica microspheres on a glass slide. Each layer is a slab consisting of a fcc close-packed colloidal arrays. By properly choosing the sizes of spheres, the whole spectral feature of multilayer colloidal crystal can be tuned. Here, we engineered a multilayer superlattice structure with an effective passband between two stop bands. This gives a strong narrowing effect on emission spectrum. With the stop bands at the shortwave and longwave edges of emission spectrum, the passband in the central wavelength region can be regarded as a strong decrease of suppression effect and enhancement of a narrow wavelength region of emission. The spectral narrowing modification effect of suitably engineered colloidal crystals shows up their importance in potential application as optical filters and lasing devices.DOI: http://dx.doi.org/10.5755/j01.ms.23.3.16320

Spectral emissivity measurements of liquid refractory metals by spectrometers combined with an electrostatic levitator

International Nuclear Information System (INIS)

Ishikawa, Takehiko; Okada, Junpei T; Paradis, Paul-François; Ito, Yusuke; Masaki, Tadahiko; Watanabe, Yuki

2012-01-01

A spectral emissivity measurement system combined with an electrostatic levitator was developed for high-temperature melts. The radiation intensity from a high-temperature sample was measured with a multichannel photospectrometer (MCPD) over the 700–1000 nm spectral range, while a Fourier transform infrared spectrometer (FTIR) measured the radiation over the 1.1–6 µm interval. These spectrometers were calibrated with a blackbody radiation furnace, and the spectral hemispherical emissivity was calculated. The system's capability was evaluated with molten zirconium samples. The spectral hemispherical emissivity of molten zirconium showed a negative wavelength dependence and an almost constant variation over the 1850–2210 K temperature range. The total hemispherical emissivity of zirconium calculated by integrating the spectral hemispherical emissivity was found to be around 0.32, which showed good agreement with the literature values. The constant pressure heat capacity of molten zirconium at melting temperature was calculated to be 40.9 J mol −1 K −1 . (paper)

Measurement of high-temperature spectral emissivity using integral blackbody approach

Science.gov (United States)

Pan, Yijie; Dong, Wei; Lin, Hong; Yuan, Zundong; Bloembergen, Pieter

2016-11-01

Spectral emissivity is one of the most critical thermophysical properties of a material for heat design and analysis. Especially in the traditional radiation thermometry, normal spectral emissivity is very important. We developed a prototype instrument based upon an integral blackbody method to measure material's spectral emissivity at elevated temperatures. An optimized commercial variable-high-temperature blackbody, a high speed linear actuator, a linear pyrometer, and an in-house designed synchronization circuit was used to implemented the system. A sample was placed in a crucible at the bottom of the blackbody furnace, by which the sample and the tube formed a simulated reference blackbody which had an effective total emissivity greater than 0.985. During the measurement, a pneumatic cylinder pushed a graphite rode and then the sample crucible to the cold opening within hundreds of microseconds. The linear pyrometer was used to monitor the brightness temperature of the sample surface, and the corresponding opto-converted voltage was fed and recorded by a digital multimeter. To evaluate the temperature drop of the sample along the pushing process, a physical model was proposed. The tube was discretized into several isothermal cylindrical rings, and the temperature of each ring was measurement. View factors between sample and rings were utilized. Then, the actual surface temperature of the sample at the end opening was obtained. Taking advantages of the above measured voltage signal and the calculated actual temperature, normal spectral emissivity under the that temperature point was obtained. Graphite sample at 1300°C was measured to prove the validity of the method.

Measurements of radiation near an atomic spectral line from the interaction of a 30 GeV electron beam and a long plasma

International Nuclear Information System (INIS)

Catravas, P.E.; Chattopadhyay, S.; Esarey, E.; Leemans, W.P.; Assmann, R.; Decker, F.-J.; Hogan, M.J.; Iverson, R.; Siemann, R.H.; Walz, D.; Whittum, D.; Blue, B.; Clayton, C; Joshi, C.; Marsh, K.A.; Mori, W.B.; Wang, S.; Katsouleas, T.; Lee, S.; Muggli, P.

2000-01-01

Emissions produced or initiated by a 30 GeV electron beam propagating through a ∼ 1 m long heat pipe oven containing neutral and partially ionized vapor have been measured near atomic spectral lines in a beam-plasma wakefield experiment. The Cerenkov spatial profile has been studied as a function of oven temperature and pressure, observation wavelength, and ionizing laser intensity and delay. The Cerenkov peak angle is affected by the creating of plasma, and estimates of neutral and plasma density have been extracted. Increases in visible background radiation, consistent with increased plasma recombination emissions due to dissipation of wakefields, were simultaneously measured

The spectral emissivity of the anode of a carbon arc.

Science.gov (United States)

Schurer, K

1968-03-01

Data in the literature on the spectral emissivity of carbon and graphite show a great divergence, ranging from 0.75 to 0.99 in the visible region. A new determination has been undertaken at a number of wavelengths using an integrating sphere and modulated light. Emissivities ranging from 0.99 in the visible to 0.96 at 0.28 micro and 1.7 micro have been found for several different graphite anodes; the values for lampblack anodes are about 0.005 lower. There is a good agreement with the highest values thus far published. Most of the literature data on the spectral radiance of the anode are consistent with the emissivities found by the present author.

Photoionization of Endohedral Atoms: Collective, Reflective and Collateral Emissions

International Nuclear Information System (INIS)

Chakraborty, Himadri S.; McCune, Matthew A.; Hopper, Dale E.; Madjet, Mohamed E.; Manson, Steven T.

2009-01-01

The photoionization properties of a fullerene-confined atom differ dramatically from that of an isolated atom. In the low energy region, where the fullerene plasmons are active, the electrons of the confined atom emerge through a collective channel carrying a significant chunk of plasmon with it. The photoelectron angular distribution of the confined atom however shows far lesser impact of the effect. At higher energies, the interference between two single-electron ionization channels, one directly from the atom and another reflected off the fullerene cage, producuces oscillatory cross sections. But for the outermost atomic level, which transfers some electrons to the cage, oscillations are further modulated by the collateral emission from the part of the atomic charge density transferred to the cage. These various modes of emissions are studied for the photoionization of Ar endohedrally confined in C 60 .

Two-dimensional sub-half-wavelength atom localization via controlled spontaneous emission.

Science.gov (United States)

Wan, Ren-Gang; Zhang, Tong-Yi

2011-12-05

We propose a scheme for two-dimensional (2D) atom localization based on the controlled spontaneous emission, in which the atom interacts with two orthogonal standing-wave fields. Due to the spatially dependent atom-field interaction, the position probability distribution of the atom can be directly determined by measuring the resulting spontaneously emission spectrum. The phase sensitive property of the atomic system leads to quenching of the spontaneous emission in some regions of the standing-waves, which significantly reduces the uncertainty in the position measurement of the atom. We find that the frequency measurement of the emitted light localizes the atom in half-wavelength domain. Especially the probability of finding the atom at a particular position can reach 100% when a photon with certain frequency is detected. By increasing the Rabi frequencies of the driving fields, such 2D sub-half-wavelength atom localization can acquire high spatial resolution.

Variational Multi-Scale method with spectral approximation of the sub-scales.

KAUST Repository

Dia, Ben Mansour

2015-01-07

A variational multi-scale method where the sub-grid scales are computed by spectral approximations is presented. It is based upon an extension of the spectral theorem to non necessarily self-adjoint elliptic operators that have an associated base of eigenfunctions which are orthonormal in weighted L2 spaces. We propose a feasible VMS-spectral method by truncation of this spectral expansion to a nite number of modes.

Variational Multi-Scale method with spectral approximation of the sub-scales.

KAUST Repository

Dia, Ben Mansour; Chá con-Rebollo, Tomas

2015-01-01

A variational multi-scale method where the sub-grid scales are computed by spectral approximations is presented. It is based upon an extension of the spectral theorem to non necessarily self-adjoint elliptic operators that have an associated base

Spectral characterization of surface emissivities in the thermal infrared

Science.gov (United States)

Niclòs, Raquel; Mira, Maria; Valor, Enric; Caselles, Diego; García-Santos, Vicente; Caselles, Vicente; Sánchez, Juan M.

2015-04-01

Thermal infrared (TIR) remote sensing trends to hyperspectral sensors on board satellites in the last decades, e.g., the current EOS-MODIS and EOS-ASTER and future missions like HyspIRI, ECOSTRESS, THIRSTY and MISTIGRI. This study aims to characterize spectrally the emissive properties of several surfaces, mostly soils. A spectrometer ranging from 2 to 16 μm, D&P Model 102, has been used to measure samples with singular spectral features, e.g. a sandy soil rich in gypsum sampled in White Sands (New Mexico, USA), salt samples, powdered quartz, and powdered calcite. These samples were chosen for their role in the assessment of thermal emissivity of soils, e.g., the calcite and quartz contents are key variables for modeling TIR emissivities of bare soils, along with soil moisture and organic matter. Additionally, the existence of large areas in the world with abundance of these materials, some of them used for calibration/validation activities of satellite sensors and products, makes the chosen samples interesting. White Sands is the world's largest gypsum dune field encompassing 400 km^2; the salt samples characterize the Salar of Uyuni (Bolivia), the largest salt flat in the world (up to 10,000 km^2), as well as the Jordanian and Israeli salt evaporation ponds at the south end of the Dead Sea, or the evaporation lagoons in Aigües-Mortes (France); and quartz is omnipresent in most of the arid regions of the world such as the Algodones Dunes or Kelso Dunes (California, USA), with areas around 700 km2 and 120 km^2, respectively. Measurements of target leaving radiance, hemispherical radiance reflected by a diffuse reflectance panel, and the radiance from a black body at different temperatures were taken to obtain thermal spectra with the D&P spectrometer. The good consistency observed between our measurements and laboratory spectra of similar samples (ASTER and MODIS spectral libraries) indicated the validity of the measurement protocol. Further, our study showed the

Determination of rare earth elements by liquid chromatography/inductively coupled plasma atomic emission spectrometry

International Nuclear Information System (INIS)

Yoshida, K.; Haraguchi, H.

1984-01-01

Inductively coupled plasma atomic emission spectrometry (ICP-AES) interfaced with high-performance liquid chromatography (HPLC) has been applied to the determination of rare earth elements. ICP-AES was used as an element-selective detector for HPLC. The separation of rare earth elements with HPLC helped to avoid erroneous analytical results due to spectral interferences. Fifteen rare earth elements (Y and 14 lanthanides) were determined selectively with the HPLC/ICP-AES system using a concentration gradient method. The detection limits with the present HPLC/ICP-AES system were about 0.001-0.3 μg/mL with a 100-μL sample injection. The calibration curves obtained by the peak height measurements showed linear relationships in the concentration range below 500 μg/mL for all rare earth elements. A USGS rock standard sample, rare earth ores, and high-purity lanthanide reagents (>99.9%) were successfully analyzed without spectral interferences

Design considerations regarding an atomizer for multi-element electrothermal atomic absorption spectrometry

Energy Technology Data Exchange (ETDEWEB)

Katskov, Dmitri A., E-mail: katskovda@tut.ac.za [Department of Chemistry, Tshwane University of Technology, Private Bag X680, Pretoria 0001 (South Africa); Sadagov, Yuri M. [All-Russian Scientific Research Institute of Optical and Physical Measurements (VNIIOFI), Ozernaya St. 46, Moscow 119361 (Russian Federation)

2011-06-15

The methodology of simultaneous multi-element electrothermal atomic absorption spectrometry (ETAAS-Electrothermal Atomic Absorption Spectrometry) stipulates rigid requirements to the design and operation of the atomizer. It must provide high degree of atomization for the group of analytes, invariant respective to the vaporization kinetics and heating ramp residence time of atoms in the absorption volume and absence of memory effects from major sample components. For the low resolution spectrometer with a continuum radiation source the reduced compared to traditional ETAAS (Electrothermal Atomic Absorption Spectrometry) sensitivity should be, at least partially, compensated by creating high density of atomic vapor in the absorption pulse. The sought-for characteristics were obtained for the 18 mm in length and 2.5 mm in internal diameter longitudinally heated graphite tube atomizer furnished with 2-4.5 mg of ring shaped carbon fiber yarn collector. The collector located next to the sampling port provides large substrate area that helps to keep the sample and its residue in the central part of the tube after drying. The collector also provides a 'platform' effect that delays the vaporization and stipulates vapor release into absorption volume having already stabilized gas temperature. Due to the shape of external surface of the tube, presence of collector and rapid (about 10 {sup o}C/ms) heating, an inverse temperature distribution along the tube is attained at the beginnings of the atomization and cleaning steps. The effect is employed for cleaning of the atomizer using the set of short maximum power heating pulses. Preparation, optimal maintenance of the atomizer and its compliance to the multi-element determination requirements are evaluated and discussed. The experimental setup provides direct simultaneous determination of large group of element within 3-4 order concentration range. Limits of detection are close to those for sequential single element

Advanced Spectral Library (ASTRAL): Atomic Fluorescence in Cool, Evolved Stars

Science.gov (United States)

Carpenter, Ken G.; Nielsen, Krister E.; Kober, Gladys V.; Rau, Gioia

2018-01-01

The "Advanced Spectral Library (ASTRAL) Project: Cool Stars" (PI = T. Ayres) collected a definitive set of representative, high-resolution (R~46,000 in the FUV up to ~1700 Å, R~30,000 for 1700-2150 Å, and R~114,000 >2150 Å) and high signal/noise (S/N>100) UV spectra of eight F-M evolved cool stars. These extremely high-quality STIS UV echelle spectra are available from the HST archive and from the Univ. of Colorado (http://casa.colorado.edu/~ayres/ASTRAL/) and will enable investigations of a broad range of problems -- stellar, interstellar, and beyond -- for many years. In this paper, we extend our study of the very rich emission-line spectra of the four evolved K-M stars in the sample, Beta Gem (K0 IIIb), Gamma Dra (K5 III), Gamma Cru (M3.4 III), and Alpha Ori (M2 Iab), to study the atomic fluorescence processes operating in their outer atmospheres. We summarize the pumping transitions and fluorescent line products known on the basis of previous work (e.g. Carpenter 1988, etc.) and newly identified in our current, on-going analysis of these extraordinary ASTRAL STIS spectra.

Multi-spectral Image Analysis for Astaxanthin Coating Classification

DEFF Research Database (Denmark)

Ljungqvist, Martin Georg; Ersbøll, Bjarne Kjær; Nielsen, Michael Engelbrecht

2011-01-01

Industrial quality inspection using image analysis on astaxanthin coating in aquaculture feed pellets is of great importance for automatic production control. In this study multi-spectral image analysis of pellets was performed using LDA, QDA, SNV and PCA on pixel level and mean value of pixels...

A Spectral Library of Emissivity Spectra for MERTIS on BepiColombo

Science.gov (United States)

Maturilli, A.; Helbert, J.; Varatharajan, I.; D'Amore, M.; Hiesinger, H.

2018-05-01

At PSL we measured emissivity spectra in vacuum for a suite of Mercury surface analogues for temperatures from 100°C to >400°C. The spectral library is completed by reflectance on samples fresh and post-heating (0.2 to 200 µm spectral range).

A Lightweight Compact Multi-Spectral Imager Using Novel Computer-Generated Micro-Optics and Spectral-Extraction Algorithms

Data.gov (United States)

National Aeronautics and Space Administration — The objective of this NASA Early-stage research proposal is to demonstrate an ultra-compact, lightweight broadband hyper- and multi-spectral imaging system that is...

Measurement of Spectral Functions of Ultracold Atoms in Disordered Potentials

Science.gov (United States)

Volchkov, Valentin V.; Pasek, Michael; Denechaud, Vincent; Mukhtar, Musawwadah; Aspect, Alain; Delande, Dominique; Josse, Vincent

2018-02-01

We report on the measurement of the spectral functions of noninteracting ultracold atoms in a three-dimensional disordered potential resulting from an optical speckle field. Varying the disorder strength by 2 orders of magnitude, we observe the crossover from the "quantum" perturbative regime of low disorder to the "classical" regime at higher disorder strength, and find an excellent agreement with numerical simulations. The method relies on the use of state-dependent disorder and the controlled transfer of atoms to create well-defined energy states. This opens new avenues for experimental investigations of three-dimensional Anderson localization.

Archives of Astronomical Spectral Observations and Atomic/Molecular Databases for their Analysis

Directory of Open Access Journals (Sweden)

Ryabchikova T.

2015-12-01

Full Text Available We present a review of open-source data for stellar spectroscopy investigations. It includes lists of the main archives of medium-to-high resolution spectroscopic observations, with brief characteristics of the archive data (spectral range, resolving power, flux units. We also review atomic and molecular databases that contain parameters of spectral lines, cross-sections and reaction rates needed for a detailed analysis of high resolution, high signal-to-noise ratio stellar spectra.

A multi-object spectral imaging instrument

OpenAIRE

Gibson, G.M.; Dienerowitz, M.; Kelleher, P.A.; Harvey, A.R.; Padgett, M.J.

2013-01-01

We have developed a snapshot spectral imaging system which fits onto the side camera port of a commercial inverted microscope. The system provides spectra, in real time, from multiple points randomly selected on the microscope image. Light from the selected points in the sample is directed from the side port imaging arm using a digital micromirror device to a spectrometer arm based on a dispersing prism and CCD camera. A multi-line laser source is used to calibrate the pixel positions on the ...

AtomPy: an open atomic-data curation environment

Science.gov (United States)

Bautista, Manuel; Mendoza, Claudio; Boswell, Josiah S; Ajoku, Chukwuemeka

2014-06-01

We present a cloud-computing environment for atomic data curation, networking among atomic data providers and users, teaching-and-learning, and interfacing with spectral modeling software. The system is based on Google-Drive Sheets, Pandas (Python Data Analysis Library) DataFrames, and IPython Notebooks for open community-driven curation of atomic data for scientific and technological applications. The atomic model for each ionic species is contained in a multi-sheet Google-Drive workbook, where the atomic parameters from all known public sources are progressively stored. Metadata (provenance, community discussion, etc.) accompanying every entry in the database are stored through Notebooks. Education tools on the physics of atomic processes as well as their relevance to plasma and spectral modeling are based on IPython Notebooks that integrate written material, images, videos, and active computer-tool workflows. Data processing workflows and collaborative software developments are encouraged and managed through the GitHub social network. Relevant issues this platform intends to address are: (i) data quality by allowing open access to both data producers and users in order to attain completeness, accuracy, consistency, provenance and currentness; (ii) comparisons of different datasets to facilitate accuracy assessment; (iii) downloading to local data structures (i.e. Pandas DataFrames) for further manipulation and analysis by prospective users; and (iv) data preservation by avoiding the discard of outdated sets.

Atlas of Atomic Spectral Lines of Neptunium Emitted by Inductively Coupled Plasma

Energy Technology Data Exchange (ETDEWEB)

DeKalb, E.L. and Edelson, M. C.

1987-08-01

Optical emission spectra from high-purity Np-237 were generated with a glovebox-enclosed inductively coupled plasma (ICP) source. Spectra covering the 230-700 nm wavelength range are presented along with general commentary on the methodology used in collecting the data. The Ames Laboratory Nuclear Safeguards and Security Program has been charged with the task of developing optical spectroscopic methods to analyze the composition of spent nuclear fuels. Such materials are highly radioactive even after prolonged 'cooling' and are chemically complex. Neptunium (Np) is a highly toxic by-product of nuclear power generation and is found, in low abundance, in spent nuclear fuels. This atlas of the optical emission spectrum of Np, as produced by an inductively coupled plasma (ICP) spectroscopic source, is part of a general survey of the ICP emission spectra of the actinide elements. The ICP emission spectrum of the actinides originates almost exclusively from the electronic relaxation of excited, singly ionized species. Spectral data on the Np ion emission spectrum (i.e., the Np II spectrum) have been reported by Tomkins and Fred [1] and Haaland [2]. Tomkins and Fred excited the Np II spectrum with a Cu spark discharge and identified 114 Np lines in the 265.5 - 436.3 nm spectral range. Haaland, who corrected some spectral line misidentifications in the work of Tomkins and Fred, utilized an enclosed Au spark discharge to excite the Np II spectrum and reported 203 Np lines within the 265.4 - 461.0 nm wavelength range.

Spectral and angle dependent emission of solar fluorescence collectors

Energy Technology Data Exchange (ETDEWEB)

Straeter, Hendrik; Knabe, Sebastian; Bauer, Gottfried H. [Institute of Physics, Carl von Ossietzky University Oldenburg, D-26111 Oldenburg (Germany)

2011-07-01

Fluorescence collectors (FCs) provide the option for concentration and simultaneous spectral selection of solar photons of direct or diffuse light. The energetic and commercial benefit of these systems depend on the yield of the conversion of solar photons into luminescence photons and on the efficiency of their respective conductance to the edges of the FC where they are coupled into appropriate solar cells. For the characterization of the performance of FCs and the identification of losses, we have performed angle and spectrally resolved measurements of fluorescence photons from FC with two different types of optical designs, a PMMA substrate with homogeneous depth dependent dye concentration and a novel type of FC, which consist of a transparent substrate with a thin overlayer containing the absorbing and emitting dye. We have recorded the edge fluorescence when illuminating the entire FC surface laterally homogeneously, as well as for slit-like excitation on the front surface with variation of the distance of the illuminated slit from the edge. We compare the experimental fluorescence results with a 2-dimensional ray-tracing approach and verify the spectral and angle dependent edge emission. Moreover we illuminate the FC with long wavelength photons which are not absorbed and conclude, again from angle dependent and spectrally resolved edge emission, on scattering losses at surfaces and in the bulk.

Differential electron emission in multi-charged ion atom collisions: Systematics for distant and close collisions

International Nuclear Information System (INIS)

DuBois, R.D.; Toburen, L.H.; Middendorf, M.E.; Jagutzki, O.

1992-09-01

Absolute doubly differential cross sections for electron emission are presented for 0.5 MeV/u multi-charged ion impact on helium, neon, and argon targets. For the helium target, Bq+, Cq+ (q = 2--5) and Oq+, Fq+ (q = 3--6) projectiles were studied; for neon and argon, only Cq+ (q = 2--5) projectiles were used. Electron emission for 10 degrees ≤ Θ ≤ 60 degrees was studied. The measured cross sections were assumed to scale as the square of an effective projectile charge, Z eff , which was determined as a function of emitted electron energy and angle. For distant collisions (low emitted electron energies), we find that Z eff ∼ q for small q and Z eff eff > Z and increases as q decreases. This is true for all angles and targets investigated

Applications of the semiclassical spectral method to nuclear, atomic, molecular, and polymeric dynamics

International Nuclear Information System (INIS)

Koszykowski, M.L.; Pfeffer, G.A.; Noid, D.W.

1987-01-01

Nonlinear dynamics plays a dominant role in a variety of important problems in chemical physics. Examples are unimolecular reactions, infrared multiphoton decomposition of molecules, the pumping process of the gamma ray laser, dissociation of vibrationally excited state-selected van der Waals's complexes, and many other chemical and atomic processes. The present article discusses recent theoretical studies on the quasi-periodic and chaotic dynamic aspects of vibrational-rotational states of atomic, nuclear, and molecular systems using the semiclassical spectral method (SSM). The authors note that the coordinates, momenta, and so on, are found using classical mechanics in the studies included in this review. They outline the semiclassical spectral method and a wide variety of applications. Although this technique was first developed ten years ago, it has proved to be tremendously successful as a tool used in dynamics problems. Applications include problems in nonlinear dynamics, molecular and atomic spectra, surface science, astronomy and stellar dynamics, nuclear physics, and polymer physics

High-precision atom localization via controllable spontaneous emission in a cycle-configuration atomic system.

Science.gov (United States)

Ding, Chunling; Li, Jiahua; Yu, Rong; Hao, Xiangying; Wu, Ying

2012-03-26

A scheme for realizing two-dimensional (2D) atom localization is proposed based on controllable spontaneous emission in a coherently driven cycle-configuration atomic system. As the spatial-position-dependent atom-field interaction, the frequency of the spontaneously emitted photon carries the information about the position of the atom. Therefore, by detecting the emitted photon one could obtain the position information available, and then we demonstrate high-precision and high-resolution 2D atom localization induced by the quantum interference between the multiple spontaneous decay channels. Moreover, we can achieve 100% probability of finding the atom at an expected position by choosing appropriate system parameters under certain conditions.

An improved feature extraction algorithm based on KAZE for multi-spectral image

Science.gov (United States)

Yang, Jianping; Li, Jun

2018-02-01

Multi-spectral image contains abundant spectral information, which is widely used in all fields like resource exploration, meteorological observation and modern military. Image preprocessing, such as image feature extraction and matching, is indispensable while dealing with multi-spectral remote sensing image. Although the feature matching algorithm based on linear scale such as SIFT and SURF performs strong on robustness, the local accuracy cannot be guaranteed. Therefore, this paper proposes an improved KAZE algorithm, which is based on nonlinear scale, to raise the number of feature and to enhance the matching rate by using the adjusted-cosine vector. The experiment result shows that the number of feature and the matching rate of the improved KAZE are remarkably than the original KAZE algorithm.

Multi-spectral optical scanners for commercial earth observation missions

Science.gov (United States)

Schröter, Karin; Engel, Wolfgang; Berndt, Klaus

2017-11-01

In recent years, a number of commercial Earth observation missions have been initiated with the aim to gather data in the visible and near-infrared wavelength range. Some of these missions aim at medium resolution (5 to 10 m) multi-spectral imaging with the special background of daily revisiting. Typical applications aim at monitoring of farming area for growth control and harvest prediction, irrigation control, or disaster monitoring such as hail damage in farming, or flood survey. In order to arrive at profitable business plans for such missions, it is mandatory to establish the space segment, i.e. the spacecraft with their opto -electronic payloads, at minimum cost while guaranteeing maximum reliability for mission success. As multiple spacecraft are required for daily revisiting, the solutions are typically based on micro-satellites. This paper presents designs for multi-spectral opto-electric scanners for this type of missions. These designs are drive n by minimum mass and power budgets of microsatellites, and the need for minimum cost. As a consequence, it is mandatory to arrive at thermally robust, compact telescope designs. The paper gives a comparison between refractive, catadioptric, and TMA optics. For mirror designs, aluminium and Zerodur mirror technologies are briefly discussed. State-of-the art focal plane designs are presented. The paper also addresses the choice of detector technologies such as CCDs and CMOS Active Pixel Sensors. The electronics of the multi-spectral scanners represent the main design driver regarding power consumption, reliability, and (most often) cost. It can be subdivided into the detector drive electronics, analog and digital data processing chains, the data mass memory unit, formatting and down - linking units, payload control electronics, and local power supply. The paper gives overviews and trade-offs between data compression strategies and electronics solutions, mass memory unit designs, and data formatting approaches

New experimental device for high-temperature normal spectral emissivity measurements of coatings

International Nuclear Information System (INIS)

Honnerová, Petra; Martan, Jiří; Kučera, Martin; Honner, Milan; Hameury, Jacques

2014-01-01

A new experimental device for normal spectral emissivity measurements of coatings in the infrared spectral range from 1.38 μm to 26 μm and in the temperature range from 550 K to 1250 K is presented. A Fourier transform infrared spectrometer (FTIR) is used for the detection of sample and blackbody spectral radiation. Sample heating is achieved by a fiber laser with a scanning head. Surface temperature is measured by two methods. The first method uses an infrared camera and a reference coating with known effective emissivity, the second method is based on the combination of Christiansen wavelength with contact and noncontact surface temperature measurement. Application of the method is shown on the example of a high-temperature high-emissivity coating. Experimental results obtained with this apparatus are compared with the results performed by a direct method of Laboratoire National d’Essais (LNE) in France. The differences in the spectra are analyzed. (paper)

The Effect of Temperature on the Spectral Emission of Plasma Induced in Water

Directory of Open Access Journals (Sweden)

B. Charfi

2013-01-01

Full Text Available A numerical modeling investigation of the spectral emission of laser-induced plasma in MgCl2-NaCl aqueous solution has been presented. A model based on equilibrium equations has been developed for the computation of the plasma composition and excited levels population. Physical interpretation is presented to comment on firstly the evolution of atomic species number densities, and secondly on the population of the excited species emitting MgII and NaI resonant lines for temperatures ranging from 3000 K to 20 000 K. It is shown that MgII line reach a maximum of population on the issuing level, at norm temperature of 13800 K. Whereas, NaI line presents two norm temperatures, evaluated at 3300 K and 11700 K. This splitting of the NaI norm temperature is explained by the low-ionization potential and weak concentration of the sodium atom in this aqueous solution. Thus, the proposed model can be useful to predict the optimal plasma temperature for the detection of given chemical element, which is not easy to reveal experimentally.

Spectral properties of X-ray selected narrow emission line galaxies

Science.gov (United States)

Romero-Colmenero, E.

1998-03-01

This thesis reports a study of the X-ray and optical properties of two samples of X-ray selected Narrow Emission Line Galaxies (NELGs), and their comparison with the properties of broad line Active Galactic Nuclei (AGN). One sample (18 NELGs) is drawn from the ROSAT International X-ray Optical Survey (RIXOS), the other (19 NELGs and 33 AGN) from the ROSAT UK Deep Survey. ROSAT multi-channel X-ray spectra have been extracted and fitted with power-law, bremsstrahlung and black body models for the brighter RIXOS sources. In most cases, power-law and bremsstrahlung models provide the best results. The average spectral energy index, alpha, of the RIXOS NELGs is 0.96 +/- 0.07, similar to that of AGN (alpha~1). For the fainter RIXOS NELGs, as well as for all the UK Deep Survey sources, counts in three spectral bands have been extracted and fitted with a power-law model, assuming the Galactic value for N_H. The brighter RIXOS sources demonstrated that the results obtained by these two different extraction and fitting procedures provide consistent results. Two average X-ray spectra, one for the NELGs and another for the AGN, were created from the UK Deep Survey sources. The power-law slope of the average NELG is alpha = 0.45 +/- 0.09, whilst that of the AGN is alpha = 0.96 +/- 0.03. ROSAT X-ray surveys have shown that the fractional surface density of NELGs increases with respect to AGN at faint fluxes (case for NELGs to be major contributors to the XRB at the fainter fluxes. The analysis of optical spectroscopy, obtained on La Palma and Hawaii, shows that NELGs form a very heterogeneous group, made up of a mixture of Seyfert 2, LINER and HII-region like galaxies. Seyfert 2 galaxies are found to possess in general the steepest X-ray slopes. Ways to explain this in the context of the unified model of AGN are discussed. The FWHM of some emission lines (Halpha, Hbeta, [NII]) in the NELGs appears to increase with steepening X-ray spectral slope. In the case of the Balmer lines

Peculiarities Of The Chemical Bond In Thorium Compounds And Fine X-Ray Photoelectron And O4,5(Th) Emission Spectral Structure

International Nuclear Information System (INIS)

Teterin, Yu.A.; Teterin, A.Yu.; Utkin, I.O.; Ivanov, K.E.; Terehov, V.A.; Ryzhkovc, M.V.; Vukchevich, L.J.

2002-01-01

On the basis of the XPS (0 - -1000 eV), x-ray 04 5(Th) low-energy (0 - 50eV) emission fine spectral structure parameters, and theoretical calculations results for electronic structure of Th, ThO 2 , and ThF 4 , the study of the Th6p-,5f- electronic states was carried out. As a result, despite the absence of the Th5f electrons in atomic Th, the Th5f atomic orbitals were established to be able to participate in the molecular orbital formation in thorium dioxide and tetrafluoride. In the MOLCAO approximation it enabled to suggest that the filled Th5f states exist in thorium compounds

Comparison of the spectral emission of lux recombinant and bioluminescent marine bacteria.

Science.gov (United States)

Thouand, Gérald; Daniel, Philippe; Horry, Habib; Picart, Pascal; Durand, Marie José; Killham, Ken; Knox, Oliver G G; DuBow, Michael S; Rousseau, Michel

2003-01-01

The purpose of the present paper was to study the influence of bacteria harbouring the luciferase-encoding Vibrio harveyi luxAB genes upon the spectral emission during growth in batch-culture conditions. In vivo bioluminescence spectra were compared from several bioluminescent strains, either naturally luminescent (Vibrio fischeri and Vibrio harveyi) or in recombinant strains (two Gram-negative Escherichia coli::luxAB strains and a Gram-positive Bacillus subtilis::luxAB strain). Spectral emission was recorded from 400 nm to 750 nm using a highly sensitive spectrometer initially devoted to Raman scattering. Two peaks were clearly identified, one at 491-500 nm (+/- 5 nm) and a second peak at 585-595 (+/- 5 nm) with the Raman CCD. The former peak was the only one detected with traditional spectrometers with a photomultiplier detector commonly used for spectral emission measurement, due to their lack of sensitivity and low resolution in the 550-650 nm window. When spectra were compared between all the studied bacteria, no difference was observed between natural or recombinant cells, between Gram-positive and Gram-negative strains, and growth conditions and growth medium were not found to modify the spectrum of light emission. Copyright 2003 John Wiley & Sons, Ltd.

Average and extreme multi-atom Van der Waals interactions: Strong coupling of multi-atom Van der Waals interactions with covalent bonding

Directory of Open Access Journals (Sweden)

Finkelstein Alexei V

2007-07-01

Full Text Available Abstract Background The prediction of ligand binding or protein structure requires very accurate force field potentials – even small errors in force field potentials can make a 'wrong' structure (from the billions possible more stable than the single, 'correct' one. However, despite huge efforts to optimize them, currently-used all-atom force fields are still not able, in a vast majority of cases, even to keep a protein molecule in its native conformation in the course of molecular dynamics simulations or to bring an approximate, homology-based model of protein structure closer to its native conformation. Results A strict analysis shows that a specific coupling of multi-atom Van der Waals interactions with covalent bonding can, in extreme cases, increase (or decrease the interaction energy by about 20–40% at certain angles between the direction of interaction and the covalent bond. It is also shown that on average multi-body effects decrease the total Van der Waals energy in proportion to the square root of the electronic component of dielectric permittivity corresponding to dipole-dipole interactions at small distances, where Van der Waals interactions take place. Conclusion The study shows that currently-ignored multi-atom Van der Waals interactions can, in certain instances, lead to significant energy effects, comparable to those caused by the replacement of atoms (for instance, C by N in conventional pairwise Van der Waals interactions.

Simultaneous determination of Cr, Ga, In and V in soil and water samples by tungsten coil atomic emission spectrometry

Energy Technology Data Exchange (ETDEWEB)

Donati, George L.; Kron, Benjamin E. [Department of Chemistry, Wake Forest University, Winston-Salem, NC 27109 (United States); Jones, Bradley T. [Department of Chemistry, Wake Forest University, Winston-Salem, NC 27109 (United States)], E-mail: jonesbt@wfu.edu

2009-06-15

Tungsten coil atomic emission spectrometry is employed for the simultaneous determination of Cr, Ga, In, and V. Both V and In are detected by this technique for the first time. The atomizer is a simple, inexpensive tungsten filament extracted from a mass-produced, commercially-available 150 W, 15 V microscope bulb. A 25 {mu}l sample aliquot is placed directly on the coil and a small constant-current power source is used to carefully dry, ash and atomize the sample. Analytical signals are detected with a Czerny-Turner spectrograph and a charge coupled device detector. Multiple emission lines from all 4 elements are monitored simultaneously in a 54 nm spectral window. Concentration limits of detection are in the {mu}g l{sup - 1} range for all elements, and the absolute limits of detection are 0.2, 2, 0.5, and 10 ng for Cr, Ga, In, and V, respectively. Even lower values may be obtained by combining the signals for the multiple emission lines of a single element. The method precision is typically better than 5.0% relative standard deviation, and sometimes as good as 0.95% (Ga). Standard reference materials of soil and water are used to check the method accuracy. After a simple acid extraction, the values determined by the method presented no significant difference from the reported values at the 95% confidence level.

Multi scales based sparse matrix spectral clustering image segmentation

Science.gov (United States)

Liu, Zhongmin; Chen, Zhicai; Li, Zhanming; Hu, Wenjin

2018-04-01

In image segmentation, spectral clustering algorithms have to adopt the appropriate scaling parameter to calculate the similarity matrix between the pixels, which may have a great impact on the clustering result. Moreover, when the number of data instance is large, computational complexity and memory use of the algorithm will greatly increase. To solve these two problems, we proposed a new spectral clustering image segmentation algorithm based on multi scales and sparse matrix. We devised a new feature extraction method at first, then extracted the features of image on different scales, at last, using the feature information to construct sparse similarity matrix which can improve the operation efficiency. Compared with traditional spectral clustering algorithm, image segmentation experimental results show our algorithm have better degree of accuracy and robustness.

Microwave-assisted versus conventional decomposition procedures applied to a ceramic potsherd standard reference material by inductively coupled plasma atomic emission spectrometry

Energy Technology Data Exchange (ETDEWEB)

Papadopoulou, D.N.; Zachariadis, G.A.; Anthemidis, A.N.; Tsirliganis, N.C.; Stratis, J.A

2004-03-03

Inductively coupled plasma atomic emission spectrometry (ICP-AES) is a powerful, sensitive analytical technique with numerous applications in chemical characterization including that of ancient pottery, mainly due to its multi-element character, and the relatively short time required for the analysis. A critical step in characterization studies of ancient pottery is the selection of a suitable decomposition procedure for the ceramic matrix. The current work presents the results of a comparative study of six decomposition procedures applied on a standard ceramic potsherd reference material, SARM 69. The investigated decomposition procedures included three microwave-assisted decomposition procedures, one wet decomposition (WD) procedure by conventional heating, one combined microwave-assisted and conventional heating WD procedure, and one fusion procedure. Chemical analysis was carried out by ICP-AES. Five major (Si, Al, Fe, Ca, Mg), three minor (Mn, Ba, Ti) and two trace (Cu, Co) elements were determined and compared with their certified values. Quantitation was performed at two different spectral lines for each element and multi-element matrix-matched calibration standards were used. The recovery values for the six decomposition procedures ranged between 75 and 110% with a few notable exceptions. Data were processed statistically in order to evaluate the investigated decomposition procedures in terms of recovery, accuracy and precision, and eventually select the most appropriate one for ancient pottery analysis.

AMARSI: Aerosol modeling and retrieval from multi-spectral imagers

NARCIS (Netherlands)

Leeuw, G. de; Curier, R.L.; Staroverova, A.; Kokhanovsky, A.; Hoyningen-Huene, W. van; Rozanov, V.V.; Burrows, J.P.; Hesselmans, G.; Gale, L.; Bouvet, M.

2008-01-01

The AMARSI project aims at the development and validation of aerosol retrieval algorithms over ocean. One algorithm will be developed for application with data from the Multi Spectral Imager (MSI) on EarthCARE. A second algorithm will be developed using the combined information from AATSR and MERIS,

Enhanced spectral emissivity of CeO2 coating with cauliflower-like microstructure

International Nuclear Information System (INIS)

Huang Jianping; Li Yibin; He Xiaodong; Song Guangping; Fan Chenglei; Sun Yue; Fei Weidong; Du Shanyi

2012-01-01

Highlights: ► Cauliflower-like microstructured CeO 2 coating is prepared on Ni based substrate. ► The infrared emissive property at high temperature is investigated. ► Rough CeO 2 coating shows high emissivity, that is, 0.9 at 873 K and 0.87 at 1073 K. ► The emissivity enhancement mechanisms for the rough CeO 2 coating are discussed. - Abstract: Cerium dioxide is a transparent oxide with high refractive index (from 1.6 to 2.5 at 633 nm) in the visible and near-IR spectral regions. However, little attention has been paid to its optical property in mid-IR (2.5–25 μm). Here we report that the cauliflower-like microstructured CeO 2 coating deposited by electron beam physical vapor deposition technique shows high emissivity up to 0.9 at 873 K in the mid-IR spectral region. The high emissivity is attributed to the coupling between free propagating waves and space-variant polarizations caused by the cauliflower-like microstructure. This high emissivity coating shows a potential application in high temperature components.

Multi-tissue partial volume quantification in multi-contrast MRI using an optimised spectral unmixing approach.

Science.gov (United States)

Collewet, Guylaine; Moussaoui, Saïd; Deligny, Cécile; Lucas, Tiphaine; Idier, Jérôme

2018-06-01

Multi-tissue partial volume estimation in MRI images is investigated with a viewpoint related to spectral unmixing as used in hyperspectral imaging. The main contribution of this paper is twofold. It firstly proposes a theoretical analysis of the statistical optimality conditions of the proportion estimation problem, which in the context of multi-contrast MRI data acquisition allows to appropriately set the imaging sequence parameters. Secondly, an efficient proportion quantification algorithm based on the minimisation of a penalised least-square criterion incorporating a regularity constraint on the spatial distribution of the proportions is proposed. Furthermore, the resulting developments are discussed using empirical simulations. The practical usefulness of the spectral unmixing approach for partial volume quantification in MRI is illustrated through an application to food analysis on the proving of a Danish pastry. Copyright © 2018 Elsevier Inc. All rights reserved.

Radical advancement in multi-spectral imaging for autonomous vehicles (UAVs, UGVs, and UUVs) using active compensation.

Energy Technology Data Exchange (ETDEWEB)

Clark, Brian F.; Bagwell, Brett E.; Wick, David Victor

2007-01-01

The purpose of this LDRD was to demonstrate a compact, multi-spectral, refractive imaging systems using active optical compensation. Compared to a comparable, conventional lens system, our system has an increased operational bandwidth, provides for spectral selectivity and, non-mechanically corrects aberrations induced by the wavelength dependent properties of a passive refractive optical element (i.e. lens). The compact nature and low power requirements of the system lends itself to small platforms such as autonomous vehicles. In addition, the broad spectral bandwidth of our system would allow optimized performance for both day/night use, and the multi-spectral capability allows for spectral discrimination and signature identification.

Atlas of Atomic Spectral Lines of Neptunium Emitted by an Inductively Coupled Plasma

International Nuclear Information System (INIS)

DeKalb, E.L.; Edelson, M.C.

1987-01-01

Optical emission spectra from high-purity Np-237 were generated with a glovebox-enclosed inductively coupled plasma (ICP) source. Spectra covering the 230-700 nm wavelength range are presented along with general commentary on the methodology used in collecting the data. The Ames Laboratory Nuclear Safeguards and Security Program has been charged with the task of developing optical spectroscopic methods to analyze the composition of spent nuclear fuels. Such materials are highly radioactive even after prolonged 'cooling' and are chemically complex. Neptunium (Np) is a highly toxic by-product of nuclear power generation and is found, in low abundance, in spent nuclear fuels. This atlas of the optical emission spectrum of Np, as produced by an inductively coupled plasma (ICP) spectroscopic source, is part of a general survey of the ICP emission spectra of the actinide elements. The ICP emission spectrum of the actinides originates almost exclusively from the electronic relaxation of excited, singly ionized species. Spectral data on the Np ion emission spectrum (i.e., the Np II spectrum) have been reported by Tomkins and Fred (1) and Haaland (2). Tomkins and Fred excited the Np II spectrum with a Cu spark discharge and identified 114 Np lines in the 265.5 - 436.3 nm spectral range. Haaland, who corrected some spectral line misidentifications in the work of Tomkins and Fred, utilized an enclosed Au spark discharge to excite the Np II spectrum and reported 203 Np lines within the 265.4 - 461.0 nm wavelength range.

Cloud-based processing of multi-spectral imaging data

Science.gov (United States)

Bernat, Amir S.; Bolton, Frank J.; Weiser, Reuven; Levitz, David

2017-03-01

Multispectral imaging holds great promise as a non-contact tool for the assessment of tissue composition. Performing multi - spectral imaging on a hand held mobile device would allow to bring this technology and with it knowledge to low resource settings to provide a state of the art classification of tissue health. This modality however produces considerably larger data sets than white light imaging and requires preliminary image analysis for it to be used. The data then needs to be analyzed and logged, while not requiring too much of the system resource or a long computation time and battery use by the end point device. Cloud environments were designed to allow offloading of those problems by allowing end point devices (smartphones) to offload computationally hard tasks. For this end we present a method where the a hand held device based around a smartphone captures a multi - spectral dataset in a movie file format (mp4) and compare it to other image format in size, noise and correctness. We present the cloud configuration used for segmenting images to frames where they can later be used for further analysis.

Line splitting and modified atomic decay of atoms coupled with N quantized cavity modes

Science.gov (United States)

Zhu, Yifu

1992-05-01

We study the interaction of a two-level atom with N non-degenerate quantized cavity modes including dissipations from atomic decay and cavity damps. In the strong coupling regime, the absorption or emission spectrum of weakly excited atom-cavity system possesses N + 1 spectral peaks whose linewidths are the weighted averages of atomic and cavity linewidths. The coupled system shows subnatural (supernatural) atomic decay behavior if the photon loss rates from the N cavity modes are smaller (larger) than the atomic decay rate. If N cavity modes are degenerate, they can be treated effectively as a single mode. In addition, we present numerical calculations for N = 2 to characterize the system evolution from the weak coupling to strong coupling limits.

On the Origin of the Flare Emission in IRIS ’ SJI 2832 Filter:Balmer Continuum or Spectral Lines?

Energy Technology Data Exchange (ETDEWEB)

Kleint, Lucia; Krucker, Säm [University of Applied Sciences and Arts Northwestern Switzerland, Bahnhofstrasse 6, 5210 Windisch (Switzerland); Heinzel, Petr [Astronomical Institute, The Czech Academy of Sciences, Fričova 298, 25165 Ondřejov (Czech Republic)

2017-03-10

Continuum (“white-light,” WL) emission dominates the energetics of flares. Filter-based observations, such as the IRIS SJI 2832 filter, show WL-like brightenings during flares, but it is unclear whether the emission arises from real continuum emission or enhanced spectral lines, possibly turning into emission. The difficulty in filter-based observations, contrary to spectral observations, is to determine which processes contribute to the observed brightening during flares. Here we determine the contribution of the Balmer continuum and the spectral line emission to IRIS ’ SJI 2832 emission by analyzing the appropriate passband in simultaneous IRIS NUV spectra. We find that spectral line emission can contribute up to 100% to the observed slitjaw images (SJI) emission, that the relative contributions usually temporally vary, and that the highest SJI enhancements that are observed are most likely because of the Balmer continuum. We conclude that care should be taken when calling SJI 2832 a continuum filter during flares, because the influence of the lines on the emission can be significant.

On the Origin of the Flare Emission in IRIS ’ SJI 2832 Filter:Balmer Continuum or Spectral Lines?

International Nuclear Information System (INIS)

Kleint, Lucia; Krucker, Säm; Heinzel, Petr

2017-01-01

Continuum (“white-light,” WL) emission dominates the energetics of flares. Filter-based observations, such as the IRIS SJI 2832 filter, show WL-like brightenings during flares, but it is unclear whether the emission arises from real continuum emission or enhanced spectral lines, possibly turning into emission. The difficulty in filter-based observations, contrary to spectral observations, is to determine which processes contribute to the observed brightening during flares. Here we determine the contribution of the Balmer continuum and the spectral line emission to IRIS ’ SJI 2832 emission by analyzing the appropriate passband in simultaneous IRIS NUV spectra. We find that spectral line emission can contribute up to 100% to the observed slitjaw images (SJI) emission, that the relative contributions usually temporally vary, and that the highest SJI enhancements that are observed are most likely because of the Balmer continuum. We conclude that care should be taken when calling SJI 2832 a continuum filter during flares, because the influence of the lines on the emission can be significant.

Hitting emissions targets with (statistical) confidence in multi-instrument Emissions Trading Schemes

International Nuclear Information System (INIS)

Shipworth, David

2003-12-01

A means of assessing, monitoring and controlling aggregate emissions from multi-instrument Emissions Trading Schemes is proposed. The approach allows contributions from different instruments with different forms of emissions targets to be integrated. Where Emissions Trading Schemes are helping to meet specific national targets, the approach allows the entry requirements of new participants to be calculated and set at a level that will achieve these targets. The approach is multi-levelled, and may be extended downwards to support pooling of participants within instruments, or upwards to embed Emissions Trading Schemes within a wider suite of policies and measures with hard and soft targets. Aggregate emissions from each instrument are treated stochastically. Emissions from the scheme as a whole are then the joint probability distribution formed by integrating the emissions from its instruments. Because a Bayesian approach is adopted, qualitative and semi-qualitative data from expert opinion can be used where quantitative data is not currently available, or is incomplete. This approach helps government retain sufficient control over emissions trading scheme targets to allow them to meet their emissions reduction obligations, while minimising the need for retrospectively adjusting existing participants' conditions of entry. This maintains participant confidence, while providing the necessary policy levers for good governance

Spectral analysis of K-shell X-ray emission of magnesium plasma

Indian Academy of Sciences (India)

2014-02-06

Feb 6, 2014 ... Spectral analysis of K-shell X-ray emission of magnesium plasma, produced by laser pulses of 45 fs duration, focussed up to an intensity of ∼1018 W cm-2, is carried out. The plasma conditions prevalent during the emission of X-ray spectrum were identified by comparing the experimental spectra with the ...

Pulse shaping for high data rate ultra-wideband wireless transmission under the Russian spectral emission mask

DEFF Research Database (Denmark)

Rommel, Simon; Grakhova, Elizaveta P.; Jurado-Navas, Antonio

2017-01-01

This paper addresses impulse-radio ultra-wideband (IR-UWB) transmission under the Russian spectral emission mask for unlicensed UWB radio communications. Four pulse shapes are proposed and their bit error rate (BER) performance is both estimated analytically and evaluated experimentally. Well......-known shapes such as the Gaussian, root-raised cosine, hyperbolic secant, and the frequency B-spline wavelet are used to form linear combinations of component pulses, shaped to make efficient use of the spectral emission mask. Analytical BER values are derived using a Nakagami-m model, and good agreement......-UWB transmission under the strict regulations of the Russian spectral emission mask....

The method of separation for evolutionary spectral density estimation of multi-variate and multi-dimensional non-stationary stochastic processes

KAUST Repository

Schillinger, Dominik

2013-07-01

The method of separation can be used as a non-parametric estimation technique, especially suitable for evolutionary spectral density functions of uniformly modulated and strongly narrow-band stochastic processes. The paper at hand provides a consistent derivation of method of separation based spectrum estimation for the general multi-variate and multi-dimensional case. The validity of the method is demonstrated by benchmark tests with uniformly modulated spectra, for which convergence to the analytical solution is demonstrated. The key advantage of the method of separation is the minimization of spectral dispersion due to optimum time- or space-frequency localization. This is illustrated by the calibration of multi-dimensional and multi-variate geometric imperfection models from strongly narrow-band measurements in I-beams and cylindrical shells. Finally, the application of the method of separation based estimates for the stochastic buckling analysis of the example structures is briefly discussed. © 2013 Elsevier Ltd.

Origin of Spectral Band Patterns in the Cosmic Unidentified Infrared Emission

Science.gov (United States)

Álvaro Galué, Héctor; Díaz Leines, Grisell

2017-10-01

The cosmic unidentified infrared emission (UIE) band phenomenon is generally considered as indicative of free-flying polycyclic aromatic hydrocarbon molecules in space. However, a coherent explanation of emission spectral band patterns depending on astrophysical source is yet to be resolved under this attribution. Meanwhile astronomers have restored the alternative origin as due to amorphous carbon particles, but assigning spectral patterns to specific structural elements of particles is equally challenging. Here we report a physical principle in which inclusion of nonplanar structural defects in aromatic core molecular structures (π domains) induces spectral patterns typical of the phenomenon. We show that defects in model π domains modulate the electronic-vibration coupling that activates the delocalized π -electron contribution to aromatic vibrational modes. The modulation naturally disperses C =C stretch modes in band patterns that readily resemble the UIE bands in the elusive 6 - 9 μ m range. The electron-vibration interaction mechanics governing the defect-induced band patterns underscores the importance of π delocalization in the emergence of UIE bands. We discuss the global UIE band regularity of this range as compatible with an emission from the delocalized s p2 phase, as π domains, confined in disordered carbon mixed-phase aggregates.

Off-resonant transitions in the collective dynamics of multi-level atomic ensembles

DEFF Research Database (Denmark)

Miroshnychenko, Yevhen; Mølmer, Klaus

2013-01-01

We study the contributions of off-resonant transitions to the dynamics of a system of N multi-level atoms sharing one excitation and interacting with the quantized vector electromagnetic field. The rotating wave approximation significantly simplifies the derivation of the equations of motion...... describing the collective atomic dynamics, but it leads to an incorrect expression for the dispersive part of the atom–atom interaction terms. For the case of two-level atoms and a scalar electromagnetic field, it turns out that the atom–atom interaction can be recovered correctly if integrals over...... the photon mode frequencies are extended to incorporate negative values. We explicitly derive the atom–atom interaction for multi-level atoms, coupled to the full vector electromagnetic field, and we recover also in this general case the validity of the results obtained by the extension to negative...

Time-resolved spectral analysis of prompt emission from long gamma-ray bursts with GeV emission

International Nuclear Information System (INIS)

Rao Arikkala Raghurama; Basak Rupal; Bhattacharya Jishnu; Chandra Sarthak; Maheshwari Nikunj; Choudhury Manojendu; Misra Ranjeev

2014-01-01

We performed detailed time-resolved spectroscopy of bright long gamma-ray bursts (GRBs) which show significant GeV emissions (GRB 080916C, GRB 090902B and GRB 090926A). In addition to the standard Band model, we also use a model consisting of a black body and a power law to fit the spectra. We find that for the latter model there are indications of an additional soft component in the spectra. While previous studies have shown that such models are required for GRB 090902B, here we find that a composite spectral model consisting of two blackbodies and a power law adequately fits the data of all the three bright GRBs. We investigate the evolution of the spectral parameters and find several interesting features that appear in all three GRBs, like (a) temperatures of the blackbodies are strongly correlated with each other, (b) fluxes in the black body components are strongly correlated with each other, (c) the temperatures of the black body trace the profile of the individual pulses of the GRBs, and (d) the characteristics of power law components like the spectral index and the delayed onset bear a close similarity to the emission characteristics in the GeV regions. We discuss the implications of these results and the possibility of identifying the radiation mechanisms during the prompt emission of GRBs. (research papers)

Continuum emission from irradiated solid deuterium

DEFF Research Database (Denmark)

Forrest, J.A.; Brooks, R.L.; Hunt, J.L.

1992-01-01

A new emission feature from the spectrum of irradiated solid deuterium has been observed in the very near-infrared spectral region. Experiments from three laboratories, using different excitation conditions, have confirmed the observation. Comparison of the timing and temperature dependence...... of the spectral feature to the information previously available from electron spin resonance studies of solid deuterium, points to atomic association as the underlying cause. We shall show the connection of this emission to the occurrence of thermal spikes and optical flashes, previously observed in solid...

Bandwidth Controllable Tunable Filter for Hyper-/Multi-Spectral Imager, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — This SBIR Phase I proposal introduces a fast speed bandwidth controllable tunable filter for hyper-/multi-spectral (HS/MS) imagers. It dynamically passes a variable...

Low-resolution continuum source simultaneous multi-element electrothermal atomic absorption spectrometry: steps into practice

International Nuclear Information System (INIS)

Katskov, Dmitri

2015-01-01

The theory and practical problems of continuum source simultaneous multi-element electrothermal atomic absorption spectrometry (SMET AAS) are discussed by the example of direct analysis of underground water. The experimental methodology is based on pulse vaporization of the sample in a fast heated graphite tube and measurement of transient absorption of continuum spectrum radiation from D 2 and Xe lamps within 200–400 nm wavelengths range with a low resolution spectral instrument and linear charge-coupled device. The setup permits the acquisition of 200 spectra during 1 s atomization pulse. Respective data matrix absorbance vs wavelength/time is employed for the quantification of elements in the sample. The calculation algorithm developed includes broad band and continuum background correction, linearization of function absorbance vs. concentration of atomic vapor and integration of thus modified absorbance at the resonance lines of the elements to be determined. Practical application shows that the method can be employed for the direct simultaneous determination of about 20 elements above microgram per liter level within 3–5 orders of the magnitude concentration range. The investigated sources of measurement errors are mainly associated with the atomization and vapor transportation problems, which are aggravated for the simultaneous release of major and minor sample constituents. Respective corrections concerning the selection of analytical lines, optimal sampling volume, matrix modification and cleaning of the atomizer have been introduced in the SMET AAS analytical technology. Under the optimized experimental conditions the calibration curves in Log-Log coordinates for all the investigated analytes in the single or multi-element reference solutions are approximated by the first order equations. The use of these equations as permanent characteristics of the setup enables instant quantification of Al, Ca, Co, Cr, Cu, Fe, Mg, Mn and Ni in the underground water

Low-resolution continuum source simultaneous multi-element electrothermal atomic absorption spectrometry: steps into practice

Energy Technology Data Exchange (ETDEWEB)

Katskov, Dmitri, E-mail: katskovda@tut.ac.za

2015-03-01

The theory and practical problems of continuum source simultaneous multi-element electrothermal atomic absorption spectrometry (SMET AAS) are discussed by the example of direct analysis of underground water. The experimental methodology is based on pulse vaporization of the sample in a fast heated graphite tube and measurement of transient absorption of continuum spectrum radiation from D{sub 2} and Xe lamps within 200–400 nm wavelengths range with a low resolution spectral instrument and linear charge-coupled device. The setup permits the acquisition of 200 spectra during 1 s atomization pulse. Respective data matrix absorbance vs wavelength/time is employed for the quantification of elements in the sample. The calculation algorithm developed includes broad band and continuum background correction, linearization of function absorbance vs. concentration of atomic vapor and integration of thus modified absorbance at the resonance lines of the elements to be determined. Practical application shows that the method can be employed for the direct simultaneous determination of about 20 elements above microgram per liter level within 3–5 orders of the magnitude concentration range. The investigated sources of measurement errors are mainly associated with the atomization and vapor transportation problems, which are aggravated for the simultaneous release of major and minor sample constituents. Respective corrections concerning the selection of analytical lines, optimal sampling volume, matrix modification and cleaning of the atomizer have been introduced in the SMET AAS analytical technology. Under the optimized experimental conditions the calibration curves in Log-Log coordinates for all the investigated analytes in the single or multi-element reference solutions are approximated by the first order equations. The use of these equations as permanent characteristics of the setup enables instant quantification of Al, Ca, Co, Cr, Cu, Fe, Mg, Mn and Ni in the underground

Multi-spectral and fluorescence diffuse optical tomography of breast cancer

Science.gov (United States)

Corlu, Alper

Multi-spectral and fluorescence diffuse optical tomography (DOT) techniques are explored and applied to image human breast cancer in vivo. Image reconstruction algorithms that utilize first and second order gradient information are described in detail. Breast DOT requires large computational memory and long run times. To this end, parallel computation techniques were developed appropriate to each reconstruction algorithm. A parallel plate DOT instrument developed for breast cancer imaging is described. The system relies heavily on continuous-wave (CW) transmission measurements and utilizes frequency domain (FD) measurements on the reemission side. However, traditional DOT image reconstruction methods based on CW measurements fail to separate tissue absorption and scattering uniquely. In this manuscript, multi-spectral DOT is shown to be capable of minimizing cross-talk and retrieving spectral parameters almost uniquely when the measurement wavelengths are optimized. A theoretical framework to select optimum wavelengths is provided, and tested with computer simulations. Results from phantom spectroscopy experiments and in vivo patient measurements support the notion that multi-spectral methods are superior to traditional DOT image reconstruction schemes. The same breast DOT instrument is improved and utilized to obtain the first in vivo images of human breast cancer based on fluorescence DOT (FDOT). To this end the fluorophore Indocyanine Green (ICG) is injected intravenously and fluorescence excitation and detection are accomplished in the soft-compression, parallel-plane, transmission geometry using laser sources at 786 nm and spectrally filtered CCD detection. Careful phantom and in vivo measurements are carried on to assure that the signals are due to ICG fluorescence, rather than tissue autofluorescence and excitation light leakage. An in vivo measurement protocol is designed to maximize the ICG contrast by acquiring full fluorescence tomographic scan during

Curve resolution and figures of merit estimation for determination of trace elements in geological materials by inductively coupled plasma atomic emission spectrometry

International Nuclear Information System (INIS)

Lorber, A.; Harel, A.; Goldbart, Z.; Brenner, I.B.

1987-01-01

In geochemical analysis using inductively coupled plasma atomic emission spectrometry (ICP-AES), spectral interferences and background enhancement in response to sample concomitants are the main cause of deterioration of the limit of detection (LOD) and inaccuracy of the determination at the trace and minor element levels. In this account, the authors describe the chemometric procedure of curve resolution for compensating for these sources of error. A newly developed method for calculating figures of merit is used to evaluate the correction procedure, test the statistical significance of the determined concentration, and determine LODs for each sample. The technique involves scanning the vicinity of the spectral line of the analyte. With prior knowledge of potential spectral interferences, deconvolution of the overlapped response is possible. Analytical data for a wide range of geological standard reference materials demonstrate the effectiveness of the chemometric techniques. Separation of 0.002 nm spectral coincidence, employing a 0.02 nm resolution spectrometer, is demonstrated

Stable multi-domain spectral penalty methods for fractional partial differential equations

Science.gov (United States)

Xu, Qinwu; Hesthaven, Jan S.

2014-01-01

We propose stable multi-domain spectral penalty methods suitable for solving fractional partial differential equations with fractional derivatives of any order. First, a high order discretization is proposed to approximate fractional derivatives of any order on any given grids based on orthogonal polynomials. The approximation order is analyzed and verified through numerical examples. Based on the discrete fractional derivative, we introduce stable multi-domain spectral penalty methods for solving fractional advection and diffusion equations. The equations are discretized in each sub-domain separately and the global schemes are obtained by weakly imposed boundary and interface conditions through a penalty term. Stability of the schemes are analyzed and numerical examples based on both uniform and nonuniform grids are considered to highlight the flexibility and high accuracy of the proposed schemes.

The source of multi spectral energy of solar energetic electron

Energy Technology Data Exchange (ETDEWEB)

Herdiwijaya, Dhani [Astronomy Division and Bosscha Observatory, Faculty Mathematics and Natural Sciences, Intitute Technology of Bandung, Ganesha 10, Bandung, Indonesia 40132 dhani@as.itb.ac.id (Indonesia)

2015-04-16

We study the solar energetic electron distribution obtained from ACE and GOES satellites which have different altitudes and electron spectral energy during the year 1997 to 2011. The electron spectral energies were 0.038–0.315 MeV from EPAM instrument onboard ACE satellite and >2 MeV from GOES satellite. We found that the low electron energy has no correlation with high energy. In spite of we have corrected to the altitude differences. It implied that they originated from time dependent events with different sources and physical processes at the solar atmosphere. The sources of multi spectral energetic electron were related to flare and CME phenomena. However, we also found that high energetic electron comes from coronal hole.

Detection of atomic and molecular hydrogen in post-discharge by resonant multi-photo-ionisation. Determination of absolute atomic densities

International Nuclear Information System (INIS)

Persuy, Philippe

1990-01-01

Within the frame of studies on devices for physical vapour deposition, and on phenomena leading to these depositions, this research thesis reports the development of a laser-diagnosis based on the phenomenon of resonant multi-photo-ionisation, and an attempt to obtain from it values of the absolute concentration of atomic hydrogen. After some recalls on the diversity of multi-photon phenomena, their theoretical and experimental evolutions, and on the particular role of hydrogen, the author reports experiments performed at 307.7 and 364.7 nm which respectively addressed the post-discharge detection of molecular hydrogen and of atomic hydrogen. A model is presented which addresses the interaction volume, and results of experiments of atom multi-photo-ionisation are reported. One of the results of this model is an assessment of the cross-section of the excitation with three photons of the hydrogen atom. This result is then used to determine the absolute density of atoms in fundamental state for different discharge conditions. Finally, the author presents the calculation software and some curve examples displaying the evolution of the number of ions and of excited states within the interaction volume [fr

Frequency lock of a dye laser emission on iron atomic line top

International Nuclear Information System (INIS)

Durand, P.

1995-03-01

The aim of this thesis is to realize a frequency lock of a dye laser emission on iron atomic line top. To reach that goal, the author first presents the calculation of atomic vapour density by means of laser absorption ratio measure and studies the dye laser working. It is then necessary to find a device giving the required precision on the frequency of the absorption line choosen. It is obtained thanks to the atomic line reconstitution by optogalvanic effect which gives the reference. Besides, the author presents the necessity of a laser emission power regulation which is obtained thanks to a device including an acoustic and optic modulator. A reliable and accurate captor is choosen and adjusted testing various hollow cathode lamps. The method to obtain the frequency lock of laser emission on iron atomic line top is described. (TEC). 18 refs., 64 figs

Cooling atoms with extraresonant stimulated emission below the Doppler limit

International Nuclear Information System (INIS)

Shevy, Y.

1989-01-01

The process of cooling atoms with radiation pressure is well understood in terms of absorption and spontaneous emission of fluorescence photons. This process imposes a lower limit on the minimum equilibrium temperature of laser cooled two level atoms of K b T = ℎΓ 21 /2 (the Doppler limit), where Γ 21 is the excited state decay rate to the ground state. At high laser intensity, it has been demonstrated that the stimulated emission process changes the sign of the force to a heating force at the red side of the atomic resonance and to a cooling force at blue detunings. Although this stimulated force is more efficient than the radiation pressure force, it has been generally accepted that this force cannot lead to lower equilibrium temperatures due to the large heating caused by diffusion of momentum at high intensity. These conclusions are valid only when the sole damping mechanism is the excited state decay to the ground state by spontaneous emission. However, when the atomic system is opened, i.e., is allowed to decay to other levels, or the dipole decay rate is altered by dephasing events, the stimulated force is dramatically modified. Under this conditions the stimulated force can occur at lower laser intensity and can even reverse sign to provide damping at the red side of resonance. These phenomena originate from extraresonances in the stimulated emission process between the two counterpropagating waves. These resonances appear as a dispersive feature in pump probe spectra (Two Wave Mixing) and are closely related to the extraresonances in four wave mixing studied originally by Bloembergen and co-workers. This paper establishes this connection and the potential of these phenomena for laser cooling. The implications of these results to the recently observed ultra-cold Na and Cs atoms are also discussed

Scattering and absorption measurements of cervical tissues measures using low cost multi-spectral imaging

Science.gov (United States)

Bernat, Amir S.; Bar-Am, Kfir; Cataldo, Leigh; Bolton, Frank J.; Kahn, Bruce S.; Levitz, David

2018-02-01

Cervical cancer is a leading cause of death for women in low resource settings. In order to better detect cervical dysplasia, a low cost multi-spectral colposcope was developed utilizing low costs LEDs and an area scan camera. The device is capable of both traditional colposcopic imaging and multi-spectral image capture. Following initial bench testing, the device was deployed to a gynecology clinic where it was used to image patients in a colposcopy setting. Both traditional colposcopic images and spectral data from patients were uploaded to a cloud server for remote analysis. Multi-spectral imaging ( 30 second capture) took place before any clinical procedure; the standard of care was followed thereafter. If acetic acid was used in the standard of care, a post-acetowhitening colposcopic image was also captured. In analyzing the data, normal and abnormal regions were identified in the colposcopic images by an expert clinician. Spectral data were fit to a theoretical model based on diffusion theory, yielding information on scattering and absorption parameters. Data were grouped according to clinician labeling of the tissue, as well as any additional clinical test results available (Pap, HPV, biopsy). Altogether, N=20 patients were imaged in this study, with 9 of them abnormal. In comparing normal and abnormal regions of interest from patients, substantial differences were measured in blood content, while differences in oxygen saturation parameters were more subtle. These results suggest that optical measurements made using low cost spectral imaging systems can distinguish between normal and pathological tissues.

Scattering of an ultrashort electromagnetic radiation pulse by an atom in a broad spectral range

International Nuclear Information System (INIS)

Astapenko, V. A.

2011-01-01

The scattering of an ultrashort electromagnetic pulse by atomic particles is described using a consistent quantum-mechanical approach taking into account excitation of a target and nondipole electromagnetic interaction, which is valid in a broad spectral range. This approach is applied to the scattering of single- and few-cycle pulses by a multielectron atom and a hydrogen atom. Scattering spectra are obtained for ultrashort pulses of different durations. The relative contribution of “elastic” scattering of a single-cycle pulse by a hydrogen atom is studied in the high-frequency limit as a function of the carrier frequency and scattering angle.

Resonant inelastic X-ray spectroscopy of atoms and simple molecules: Satellite features and dependence on energy detuning and photon polarization

Energy Technology Data Exchange (ETDEWEB)

Žitnik, M., E-mail: matjaz.zitnik@ijs.si [Jožef Stefan Institute, P.O. Box 3000, SI-1001 Ljubljana (Slovenia); University of Ljubljana, Faculty of Mathematics and Physics, Jadranska 21, SI-1000 Ljubljana (Slovenia); Kavčič, M.; Bohinc, R.; Bučar, K.; Mihelič, A. [Jožef Stefan Institute, P.O. Box 3000, SI-1001 Ljubljana (Slovenia); Cao, W. [Research Centre for Molecular Materials, University of Oulu, P.O. Box 3000, FIN-90014 Oulu (Finland); Guillemin, R.; Journel, L.; Marchenko, T.; Carniato, S.; Kawerk, E. [Sorbonne Universités, UPMC Univ Paris 06, UMR 7614, Laboratoire de Chimie Physique Matière et Rayonnement, F-75005 Paris (France); CNRS, UMR 7614, Laboratoire de Chimie Physique Matière et Rayonnement, F-75005 Paris (France); Piancastelli, M.N. [Sorbonne Universités, UPMC Univ Paris 06, UMR 7614, Laboratoire de Chimie Physique Matière et Rayonnement, F-75005 Paris (France); CNRS, UMR 7614, Laboratoire de Chimie Physique Matière et Rayonnement, F-75005 Paris (France); Department of Physics and Astronomy, Uppsala University, P.O. Box 516, 75120 Uppsala (Sweden); Simon, M. [Sorbonne Universités, UPMC Univ Paris 06, UMR 7614, Laboratoire de Chimie Physique Matière et Rayonnement, F-75005 Paris (France); CNRS, UMR 7614, Laboratoire de Chimie Physique Matière et Rayonnement, F-75005 Paris (France)

2015-10-15

We summarize recent results dealing with high resolution (resonant) X-ray spectroscopy of atomic and molecular targets in the tender X-ray energy region. We comment on advantages, new possibilities and problems related to RIXS spectroscopy with respect to the standard photoabsorption technique, where scanning the probe energy is the only option. In particular, three research areas are covered: X-ray emission mediated by energy dependent photoabsorption to multi-electron excited states, the Cl K core-hole clock studies exemplified by systematic study of chloro(fluoro)-hydrocarbon targets and the polarization dependent X-ray emission studies. Due to its spectral selectivity and simultaneous detection capability, high resolution wavelength dispersive X-ray spectroscopy has the capability to resolve structural and dynamical properties of matter within new instrumentation frontiers.

Resonant inelastic X-ray spectroscopy of atoms and simple molecules: Satellite features and dependence on energy detuning and photon polarization

International Nuclear Information System (INIS)

Žitnik, M.; Kavčič, M.; Bohinc, R.; Bučar, K.; Mihelič, A.; Cao, W.; Guillemin, R.; Journel, L.; Marchenko, T.; Carniato, S.; Kawerk, E.; Piancastelli, M.N.; Simon, M.

2015-01-01

We summarize recent results dealing with high resolution (resonant) X-ray spectroscopy of atomic and molecular targets in the tender X-ray energy region. We comment on advantages, new possibilities and problems related to RIXS spectroscopy with respect to the standard photoabsorption technique, where scanning the probe energy is the only option. In particular, three research areas are covered: X-ray emission mediated by energy dependent photoabsorption to multi-electron excited states, the Cl K core-hole clock studies exemplified by systematic study of chloro(fluoro)-hydrocarbon targets and the polarization dependent X-ray emission studies. Due to its spectral selectivity and simultaneous detection capability, high resolution wavelength dispersive X-ray spectroscopy has the capability to resolve structural and dynamical properties of matter within new instrumentation frontiers.

Development of the Flame Test Concept Inventory: Measuring Student Thinking about Atomic Emission

Science.gov (United States)

Bretz, Stacey Lowery; Murata Mayo, Ana Vasquez

2018-01-01

This study reports the development of a 19-item Flame Test Concept Inventory, an assessment tool to measure students' understanding of atomic emission. Fifty-two students enrolled in secondary and postsecondary chemistry courses were interviewed about atomic emission and explicitly asked to explain flame test demonstrations and energy level…

Investigation of spectral interferences in the determination of lead in fertilizers and limestone samples using high-resolution continuum source graphite furnace atomic absorption spectrometry

Energy Technology Data Exchange (ETDEWEB)

Borges, Aline R. [Instituto de Química, Universidade Federal do Rio Grande do Sul, Av. Bento Gonçalves 9500, 91501-970 Porto Alegre, RS (Brazil); Instituto Nacional de Ciência e Tecnologia do CNPq — INCT de Energia e Ambiente, Universidade Federal da Bahia, Salvador, BA (Brazil); Becker, Emilene M.; François, Luciane L.; Jesus, Alexandre de [Instituto de Química, Universidade Federal do Rio Grande do Sul, Av. Bento Gonçalves 9500, 91501-970 Porto Alegre, RS (Brazil); Vale, Maria Goreti R. [Instituto de Química, Universidade Federal do Rio Grande do Sul, Av. Bento Gonçalves 9500, 91501-970 Porto Alegre, RS (Brazil); Instituto Nacional de Ciência e Tecnologia do CNPq — INCT de Energia e Ambiente, Universidade Federal da Bahia, Salvador, BA (Brazil); Welz, Bernhard [Instituto Nacional de Ciência e Tecnologia do CNPq — INCT de Energia e Ambiente, Universidade Federal da Bahia, Salvador, BA (Brazil); Departamento de Química, Universidade Federal de Santa Catarina, 88040-900 Florianópolis, SC (Brazil); Dessuy, Morgana B., E-mail: mbdessuy@ufrgs.br [Instituto de Química, Universidade Federal do Rio Grande do Sul, Av. Bento Gonçalves 9500, 91501-970 Porto Alegre, RS (Brazil); Andrade, Jailson B. de [Instituto Nacional de Ciência e Tecnologia do CNPq — INCT de Energia e Ambiente, Universidade Federal da Bahia, Salvador, BA (Brazil)

2014-11-01

In the present work, spectral interferences on the determination of lead in fertilizer and limestone samples were investigated using high-resolution continuum source graphite furnace atomic absorption spectrometry at the main analytical lines: 217.001 and 283.306 nm. For these investigations, samples were introduced into the furnace as slurry together with a mixture of Pd and Mg as chemical modifier. Spectral interferences were observed for some samples at both analytical lines. In order to verify whether a wet digestion procedure would avoid these interferences, a reference method for wet digestion of fertilizers was employed as an alternative sample preparation procedure. However, the same interferences were also observed in the digested samples. In order to identify and eliminate the fine-structured background using a least-squares background correction, reference spectra were generated using the combination of different species. The use of the latter technique allowed the elimination of spectral interferences for most of the investigated samples, making possible the determination of lead in fertilizer and limestone samples free of interferences. The best results were found using a reference spectrum of NH{sub 4}H{sub 2}PO{sub 4} at 217.001 nm, and a mixture of H{sub 2}SO{sub 4} + Ca and HNO{sub 3} + Ca at the 283.306 nm line. The accuracy of the method was evaluated using a certified reference material “Trace Elements in Multi-Nutrient Fertilizer”. Similar results were obtained using line source graphite furnace atomic absorption spectrometry with Zeeman-effect background correction, indicating that the latter technique was also capable to correct the spectral interferences, at least in part. - Highlights: • Spectral interferences on the determination of lead in fertilizers and limestone. • The analytical lines at 217.001 nm and 283.306 nm using HR-CS GF AAS. • Various combinations of compounds were used to create reference spectra. • LSBC

Enhanced spectral emissivity of CeO{sub 2} coating with cauliflower-like microstructure

Energy Technology Data Exchange (ETDEWEB)

Huang Jianping [Center for Composite Materials and Structures, Harbin Institute of Technology, 150080 Harbin (China); Li Yibin, E-mail: liyibin@hit.edu.cn [Center for Composite Materials and Structures, Harbin Institute of Technology, 150080 Harbin (China); He Xiaodong; Song Guangping [Center for Composite Materials and Structures, Harbin Institute of Technology, 150080 Harbin (China); Fan Chenglei [Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, 150001 Harbin (China); Sun Yue [Center for Composite Materials and Structures, Harbin Institute of Technology, 150080 Harbin (China); Fei Weidong [School of Materials Science and Engineering, Harbin Institute of Technology, 150001 Harbin (China); Du Shanyi [Center for Composite Materials and Structures, Harbin Institute of Technology, 150080 Harbin (China)

2012-10-15

Highlights: Black-Right-Pointing-Pointer Cauliflower-like microstructured CeO{sub 2} coating is prepared on Ni based substrate. Black-Right-Pointing-Pointer The infrared emissive property at high temperature is investigated. Black-Right-Pointing-Pointer Rough CeO{sub 2} coating shows high emissivity, that is, 0.9 at 873 K and 0.87 at 1073 K. Black-Right-Pointing-Pointer The emissivity enhancement mechanisms for the rough CeO{sub 2} coating are discussed. - Abstract: Cerium dioxide is a transparent oxide with high refractive index (from 1.6 to 2.5 at 633 nm) in the visible and near-IR spectral regions. However, little attention has been paid to its optical property in mid-IR (2.5-25 {mu}m). Here we report that the cauliflower-like microstructured CeO{sub 2} coating deposited by electron beam physical vapor deposition technique shows high emissivity up to 0.9 at 873 K in the mid-IR spectral region. The high emissivity is attributed to the coupling between free propagating waves and space-variant polarizations caused by the cauliflower-like microstructure. This high emissivity coating shows a potential application in high temperature components.

Spectral Evolution of Synchrotron and Inverse Compton Emission in ...

Indian Academy of Sciences (India)

emission peaks in the optical band (e.g., Nieppola et al. 2006). In order to under- stand the evolution of synchrotron and IC spectra of BL Lac objects, the X-ray spectral analysis with XMM–Newton X-ray observations of PKS 2155–304 and. S5 0716+7145 (see Zhang 2008, 2010 for details) was performed. Here, the results.

Multi-photon ionization of atoms in intense short-wavelength radiation fields

Science.gov (United States)

Meyer, Michael

2015-05-01

The unprecedented characteristics of XUV and X-ray Free Electron Lasers (FELs) have stimulated numerous investigations focusing on the detailed understanding of fundamental photon-matter interactions in atoms and molecules. In particular, the high intensities (up to 106 W/cm2) giving rise to non-linear phenomena in the short wavelength regime. The basic phenomenology involves the production of highly charged ions via electron emission to which both sequential and direct multi-photon absorption processes contribute. The detailed investigation of the role and relative weight of these processes under different conditions (wavelength, pulse duration, intensity) is the key element for a comprehensive understanding of the ionization dynamics. Here the results of recent investigations are presented, performed at the FELs in Hamburg (FLASH) and Trieste (FERMI) on atomic systems with electronic structures of increasing complexity (Ar, Ne and Xe). Mainly, electron spectroscopy is used to obtain quantitative information about the relevance of various multi-photon ionization processes. For the case of Ar, a variety of processes including above threshold ionization (ATI) from 3p and 3s valence shells, direct 2p two-photon ionization and resonant 2p-4p two-photon excitations were observed and their role was quantitatively determined comparing the experimental ionization yields to ab-initio calculations of the cross sections for the multi-photon processes. Using Ar as a benchmark to prove the reliability of the combined experimental and theoretical approach, the more complex and intriguing case of Xe was studied. Especially, the analysis of the two-photon ATI from the Xe 4d shell reveals new insight into the character of the 4d giant resonance, which was unresolved in the linear one-photon regime. Finally, the influence of intense XUV radiation to the relaxation dynamics of the Ne 2s-3p resonance was investigated by angle-resolved electron spectroscopy, especially be observing

HARD X-RAY AND MICROWAVE EMISSIONS FROM SOLAR FLARES WITH HARD SPECTRAL INDICES

Energy Technology Data Exchange (ETDEWEB)

Kawate, T. [Kwasan and Hida Observatory, Kitashirakawa-oiwakecho, Sakyo, Kyoto 606-8502 (Japan); Nishizuka, N. [Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3-1-1 Yoshinodai, Chuo-ku, Sagamihara, Kanagawa 229-8510 (Japan); Oi, A. [College of Science, Ibaraki University, Mito, Ibaraki 310-8512 (Japan); Ohyama, M. [Faculty of Education, Shiga University, 2-5-1 Hiratsu, Otsu, Shiga 1-1, Baba Hikone city, Siga 522-8522 (Japan); Nakajima, H., E-mail: kawate@kusastro.kyoto-u.ac.jp [Nobeyama Solar Radio Observatory, NAOJ, Nobeyama, Minamisaku, Nagano 384-1305 (Japan)

2012-03-10

We analyze 10 flare events that radiate intense hard X-ray (HXR) emission with significant photons over 300 keV to verify that the electrons that have a common origin of acceleration mechanism and energy power-law distribution with solar flares emit HXRs and microwaves. Most of these events have the following characteristics. HXRs emanate from the footpoints of flare loops, while microwaves emanate from the tops of flare loops. The time profiles of the microwave emission show delays of peak with respect to those of the corresponding HXR emission. The spectral indices of microwave emissions show gradual hardening in all events, while the spectral indices of the corresponding HXR emissions are roughly constant in most of the events, though rather rapid hardening is simultaneously observed in some for both indices during the onset time and the peak time. These characteristics suggest that the microwave emission emanates from the trapped electrons. Then, taking into account the role of the trapping of electrons for the microwave emission, we compare the observed microwave spectra with the model spectra calculated by a gyrosynchrotron code. As a result, we successfully reproduce the eight microwave spectra. From this result, we conclude that the electrons that have a common acceleration and a common energy distribution with solar flares emit both HXR and microwave emissions in the eight events, though microwave emission is contributed to by electrons with much higher energy than HXR emission.

NuSTAR OBSERVATIONS OF GRB 130427A ESTABLISH A SINGLE COMPONENT SYNCHROTRON AFTERGLOW ORIGIN FOR THE LATE OPTICAL TO MULTI-GEV EMISSION

International Nuclear Information System (INIS)

Kouveliotou, C.; Granot, J.; Racusin, J. L.; Gehrels, N.; McEnery, J. E.; Zhang, W. W.; Bellm, E.; Harrison, F. A.; Vianello, G.; Oates, S.; Fryer, C. L.; Boggs, S. E.; Craig, W. W.; Christensen, F. E.; Dermer, C. D.; Hailey, C. J.; Melandri, A.; Tagliaferri, G.; Mundell, C. G.; Stern, D. K.

2013-01-01

GRB 130427A occurred in a relatively nearby galaxy; its prompt emission had the largest GRB fluence ever recorded. The afterglow of GRB 130427A was bright enough for the Nuclear Spectroscopic Telescope ARray (NuSTAR) to observe it in the 3-79 keV energy range long after its prompt emission (∼1.5 and 5 days). This range, where afterglow observations were previously not possible, bridges an important spectral gap. Combined with Swift, Fermi, and ground-based optical data, NuSTAR observations unambiguously establish a single afterglow spectral component from optical to multi-GeV energies a day after the event, which is almost certainly synchrotron radiation. Such an origin of the late-time Fermi/Large Area Telescope >10 GeV photons requires revisions in our understanding of collisionless relativistic shock physics

Combustor exhaust-emissions and blowout-limits with diesel number 2 and Jet A fuels utilizing air-atomizing and pressure-atomizing nozzles

Science.gov (United States)

Ingebo, R. D.; Norgren, C. T.

1975-01-01

The effect of fuel properties on exhaust emissions and blowout limits of a high-pressure combustor segment is evaluated using a splash-groove air-atomizing fuel injector and a pressure-atomizing simplex fuel nozzle to burn both diesel number 2 and Jet A fuels. Exhaust emissions and blowout data are obtained and compared on the basis of the aromatic content and volatility of the two fuels. Exhaust smoke number and emission indices for oxides of nitrogen, carbon monoxide, and unburned hydrocarbons are determined for comparison. As compared to the pressure-atomizing nozzle, the air-atomizing nozzle is found to reduce nitrogen oxides by 20%, smoke number by 30%, carbon monoxide by 70%, and unburned hydrocarbons by 50% when used with diesel number 2 fuel. The higher concentration of aromatics and lower volatility of diesel number 2 fuel as compared to Jet A fuel appears to have the most detrimental effect on exhaust emissions. Smoke number and unburned hydrocarbons are twice as high with diesel number 2 as with Jet A fuel.

Determination numbers of ionized atoms from emission and absorption lines

International Nuclear Information System (INIS)

Alizadeh Azimi, A.; Shokouhi, N.

2002-01-01

Saha, M., (1920) estimated that salter chromosphere is not only due to radiation from neutral atoms, but from ionized atoms. The failure to observe these stellar lines in the laboratory was attributed to internal temperature and pressure about 10* E + 6 K 10* E-7 atm. In this research we found that emission lines of ionized atoms (like Cs) could be measured in laboratory condition, (about 10* E-3 atm and 2000 K) by using Graphite France Atomic Absorption with injection 124 u g C sel. We calculated the numbers of ionized atoms from Bottzman law. We also measured these numbers from area under the energy-time curve

The MIND PALACE: A Multi-Spectral Imaging and Spectroscopy Database for Planetary Science

Science.gov (United States)

Eshelman, E.; Doloboff, I.; Hara, E. K.; Uckert, K.; Sapers, H. M.; Abbey, W.; Beegle, L. W.; Bhartia, R.

2017-12-01

The Multi-Instrument Database (MIND) is the web-based home to a well-characterized set of analytical data collected by a suite of deep-UV fluorescence/Raman instruments built at the Jet Propulsion Laboratory (JPL). Samples derive from a growing body of planetary surface analogs, mineral and microbial standards, meteorites, spacecraft materials, and other astrobiologically relevant materials. In addition to deep-UV spectroscopy, datasets stored in MIND are obtained from a variety of analytical techniques obtained over multiple spatial and spectral scales including electron microscopy, optical microscopy, infrared spectroscopy, X-ray fluorescence, and direct fluorescence imaging. Multivariate statistical analysis techniques, primarily Principal Component Analysis (PCA), are used to guide interpretation of these large multi-analytical spectral datasets. Spatial co-referencing of integrated spectral/visual maps is performed using QGIS (geographic information system software). Georeferencing techniques transform individual instrument data maps into a layered co-registered data cube for analysis across spectral and spatial scales. The body of data in MIND is intended to serve as a permanent, reliable, and expanding database of deep-UV spectroscopy datasets generated by this unique suite of JPL-based instruments on samples of broad planetary science interest.

Standard practice for analysis of aqueous leachates from nuclear waste materials using inductively coupled plasma-atomic emission spectrometry

CERN Document Server

American Society for Testing and Materials. Philadelphia

2010-01-01

1.1 This practice is applicable to the determination of low concentration and trace elements in aqueous leachate solutions produced by the leaching of nuclear waste materials, using inductively coupled plasma-atomic emission spectroscopy (ICP-AES). 1.2 The nuclear waste material may be a simulated (non-radioactive) solid waste form or an actual solid radioactive waste material. 1.3 The leachate may be deionized water or any natural or simulated leachate solution containing less than 1 % total dissolved solids. 1.4 This practice should be used by analysts experienced in the use of ICP-AES, the interpretation of spectral and non-spectral interferences, and procedures for their correction. 1.5 No detailed operating instructions are provided because of differences among various makes and models of suitable ICP-AES instruments. Instead, the analyst shall follow the instructions provided by the manufacturer of the particular instrument. This test method does not address comparative accuracy of different devices...

Spectrum of a one-atom laser in photonic crystals

International Nuclear Information System (INIS)

Florescu, Lucia

2006-01-01

The emission spectrum of a single-emitter laser in a photonic crystal is presented. We consider a coherently pumped two-level emitter strongly coupled to a high-quality microcavity engineered within a photonic crystal. We show that the cavity spectrum consists of both elastic and inelastic components, for which we derive analytical expressions. Our study reveals enhanced, spectrally narrower emission resulting from the radiation reservoir of the photonic crystal. The cavity field spectral characteristics are fundamentally distinct from those of a corresponding microcavity in ordinary vacuum. At high pump intensities and for large discontinuities in the photon density of states between Mollow spectral components of atomic resonance fluorescence, the emitted intensity originating from the elastic spectral component increases with the intensity of the pump and the elastic component dominates the spectrum. In the case of a vanishing photon density of states in the spectral range surrounding the lower Mollow sideband and no dipolar dephasing, the cavity spectrum is elastic

Nitrogen Atom Energy Distributions in a Hollow-cathode Planar Sputtering Magnetron

International Nuclear Information System (INIS)

Ruzic, D.N.; Goeckner, M.J.; Cohen, S.A.; Wang, Zhehui

1999-01-01

Energy distributions of N atoms in a hollow-cathode planar sputtering magnetron were obtained by use of optical emission spectroscopy. A characteristic line, N I 8216.3 , well-separated from molecular nitrogen emission bands, was identified. Jansson's nonlinear spectral deconvolution method, refined by minimization of χ w ampersand sup2; , was used to obtain the optimal deconvolved spectra. These showed nitrogen atom energies from 1 eV to beyond 500 eV. Based on comparisons with VFTRIM results, we propose that the energetic N atoms are generated from N 2 + ions after these ions are accelerated through the sheath and dissociatively reflect from the cathode

Superradiant cascade emissions in an atomic ensemble via four-wave mixing

Energy Technology Data Exchange (ETDEWEB)

Jen, H.H., E-mail: sappyjen@gmail.com

2015-09-15

We investigate superradiant cascade emissions from an atomic ensemble driven by two-color classical fields. The correlated pair of photons (signal and idler) is generated by adiabatically driving the system with large-detuned light fields via four-wave mixing. The signal photon from the upper transition of the diamond-type atomic levels is followed by the idler one which can be superradiant due to light-induced dipole–dipole interactions. We then calculate the cooperative Lamb shift (CLS) of the idler photon, which is a cumulative effect of interaction energy. We study its dependence on a cylindrical geometry, a conventional setup in cold atom experiments, and estimate the maximum CLS which can be significant and observable. Manipulating the CLS of cascade emissions enables frequency qubits that provide alternative robust elements in quantum network. - Highlights: • Superradiance from a cascade atomic transition. • Correlated photon pair generation via four-wave mixing. • Dynamical light–matter couplings in a phased symmetrical state. • Cooperative Lamb shift in a cylindrical atomic ensemble.

Spectral evolution of soft x-ray emission from optically thin, high electron temperature platinum plasmas

Directory of Open Access Journals (Sweden)

Hiroyuki Hara

2017-08-01

Full Text Available The soft x-ray spectra of heavy element plasmas are frequently dominated by unresolved transition array (UTA emission. We describe the spectral evolution of an intense UTA under optically thin conditions in platinum plasmas. The UTA was observed to have a peak wavelength around 4.6 nm at line-of-sight averaged electron temperatures less than 1.4 keV at electron densities of (2.5–7.5 × 1013 cm−3. The UTA spectral structure was due to emission from 4d–4f transitions in highly charged ions with average charge states of q = 20–40. A numerical simulation successfully reproduced the observed spectral behavior.

Using the van der Waals broadening of the spectral atomic lines to measure the gas temperature of an argon microwave plasma at atmospheric pressure

International Nuclear Information System (INIS)

Yubero, C.; Dimitrijevic, M.S.; Garcia, M.C.; Calzada, M.D.

2007-01-01

The ro-vibrational emission spectra of the molecular species are usually used to measure the gas temperature of a discharge at atmospheric pressure. However, under some experimental conditions, it is difficult to detect them. In order to overcome this difficulty and obtain the temperature, there are methods based on the relation between the gas temperature and the van der Waals broadening of argon atomic spectral lines with a Stark contribution negligible. In this work, we propose a method based on this relation but for lines with a Stark broadening comparable with the van der Waals one

Broadband spectral study of the jet-disc emission in the radio-loud narrow-line Seyfert 1 galaxy 1H 0323+342

Science.gov (United States)

Ghosh, Ritesh; Dewangan, Gulab C.; Mallick, Labani; Raychaudhuri, Biplab

2018-06-01

We present a broadband spectral study of the radio-loud narrow-line Seyfert 1 galaxy 1H 0323+342 based on multi-epoch observations performed with NuSTAR on 2014 March 15, and two simultaneous observations performed with Suzaku and Swift on 2009 July 26 and 2013 March 1. We found the presence of a strong soft X-ray excess emission, a broad but weak Fe line and hard X-ray excess emission. We used the blurred reflection (relxill) and the intrinsic disc Comptonization (optxagnf), two physically motivated models, to describe the broadband spectra and to disentangle the disk/corona and jet emission. The relxill model is mainly constrained by the strong soft X-ray excess although the model failed to predict this excess when fitted above 3{keV} and extrapolated to lower energies. The joint spectral analysis of the three datasets above 3{keV} with this model resulted in a high black hole spin (a > 0.9) and moderate reflection fraction R ˜ 0.5. The optxagnf model fitted to the two simultaneous datasets resulted in an excess emission in the UV band. The simultaneous UV-to-hard X-ray spectra of 1H 0323+342 are best described by a model consisting of a primary X-ray power-law continuum with Γ ˜ 1.8, a blurred reflection component with R ˜ 0.5, Comptonised disk emission as the soft X-ray excess, optical/UV emission from a standard accretion disk around a black hole of mass ˜107M⊙ and a steep power law (Γ ˜ 3 - 3.5) component, most likely the jet emission in the UV band. The fractional RMS variability spectra suggest that both the soft excess and the powerlaw component are variable in nature.

Exploiting High Resolution Multi-Seasonal Textural Measures and Spectral Information for Reedbed Mapping

Directory of Open Access Journals (Sweden)

Alex Okiemute Onojeghuo

2016-02-01

Full Text Available Reedbeds across the UK are amongst the most important habitats for rare and endangered birds, wildlife and organisms. However, over the past century, this valued wetland habitat has experienced a drastic reduction in quality and spatial coverage due to pressures from human related activities. To this end, conservation organisations across the UK have been charged with the task of conserving and expanding this threatened habitat. With this backdrop, the study aimed to develop a methodology for accurate reedbed mapping through the combined use of multi-seasonal texture measures and spectral information contained in high resolution QuickBird satellite imagery. The key objectives were to determine the most effective single-date (autumn or summer and multi-seasonal QuickBird imagery suitable for reedbed mapping over the study area; to evaluate the effectiveness of combining multi-seasonal texture measures and spectral information for reedbed mapping using a variety of combinations; and to evaluate the most suitable classification technique for reedbed mapping from three selected classification techniques, namely maximum likelihood classifier, spectral angular mapper and artificial neural network. Using two selected grey-level co-occurrence textural measures (entropy and angular second moment, a series of experiments were conducted using varied combinations of single-date and multi-seasonal QuickBird imagery. Overall, the results indicate the multi-seasonal pansharpened multispectral bands (eight layers combined with all eight grey level co-occurrence matrix texture measures (entropy and angular second moment computed using windows 3 × 3 and 7 × 7 produced the optimal reedbed (76.5% and overall classification (78.1% accuracies using the maximum likelihood classifier technique. Using the optimal 16 layer multi-seasonal pansharpened multispectral and texture combined image dataset, a total reedbed area of 9.8 hectares was successfully mapped over the

Coherent effects on two-photon correlation and directional emission of two two-level atoms

International Nuclear Information System (INIS)

Ooi, C. H. Raymond; Kim, Byung-Gyu; Lee, Hai-Woong

2007-01-01

Sub- and superradiant dynamics of spontaneously decaying atoms are manifestations of collective many-body systems. We study the internal dynamics and the radiation properties of two atoms in free space. Interesting results are obtained when the atoms are separated by less than half a wavelength of the atomic transition, where the dipole-dipole interaction gives rise to new coherent effects, such as (a) coherence between two intermediate collective states, (b) oscillations in the two-photon correlation G (2) , (c) emission of two photons by one atom, and (d) the loss of directional correlation. We compare the population dynamics during the two-photon emission process with the dynamics of single-photon emission in the cases of a Λ and a V scheme. We compute the temporal correlation and angular correlation of two successively emitted photons using the G (2) for different values of atomic separation. We find antibunching when the atomic separation is a quarter wavelength λ/4. Oscillations in the temporal correlation provide a useful feature for measuring subwavelength atomic separation. Strong directional correlation between two emitted photons is found for atomic separation larger than a wavelength. We also compare the directionality of a photon spontaneously emitted by the two atoms prepared in phased-symmetric and phased-antisymmetric entangled states vertical bar ±> k 0 =e ik 0 ·r 1 vertical bar a 1 ,b 2 >±e ik 0 ·r 2 vertical bar b 1 ,a 2 > by a laser pulse with wave vector k 0 . Photon emission is directionally suppressed along k 0 for the phased-antisymmetric state. The directionality ceases for interatomic distances less than λ/2

Effective Spectral Indices of Core and Extended Emissions for Radio ...

Indian Academy of Sciences (India)

Effective Spectral Indices of Core and Extended Emissions for Radio Sources. R. S. Yang1,∗, J. H. Yang1,2 & J. J. Nie1. 1Department of Physics and Electronics Science, Hunan University of Arts and Science,. Changde 415000, China. 2Centre for Astrophysics, Guangzhou University, Guangzhou 510006, China. ∗ e-mail: ...

THE ULTRAVIOLET-TO-MID-INFRARED SPECTRAL ENERGY DISTRIBUTION OF WEAK EMISSION LINE QUASARS

International Nuclear Information System (INIS)

Lane, Ryan A.; Shemmer, Ohad; Diamond-Stanic, Aleksandar M.; Fan Xiaohui; Anderson, Scott F.; Brandt, W. N.; Schneider, Donald P.; Plotkin, Richard M.; Richards, Gordon T.; Strauss, Michael A.

2011-01-01

We present Spitzer Space Telescope photometry of 18 Sloan Digital Sky Survey (SDSS) quasars at 2.7 ≤ z ≤ 5.9 which have weak or undetectable high-ionization emission lines in their rest-frame ultraviolet (UV) spectra (hereafter weak-lined quasars, or WLQs). The Spitzer data are combined with SDSS spectra and ground-based, near-infrared (IR) photometry of these sources to produce a large inventory of spectral energy distributions (SEDs) of WLQs across the rest-frame ∼0.1-5 μm spectral band. The SEDs of our sources are inconsistent with those of BL Lacertae objects which are dominated by synchrotron emission due to a jet aligned close to our line of sight, but are consistent with the SED of ordinary quasars with similar luminosities and redshifts that exhibit a near-to-mid-IR 'bump', characteristic of hot dust emission. This indicates that broad emission lines in WLQs are intrinsically weak, rather than suffering continuum dilution from a jet, and that such sources cannot be selected efficiently from traditional photometric surveys.

THE ULTRAVIOLET-TO-MID-INFRARED SPECTRAL ENERGY DISTRIBUTION OF WEAK EMISSION LINE QUASARS

Energy Technology Data Exchange (ETDEWEB)

Lane, Ryan A.; Shemmer, Ohad [Department of Physics, University of North Texas, Denton, TX 76203 (United States); Diamond-Stanic, Aleksandar M. [Center for Astrophysics and Space Sciences, University of California, San Diego, La Jolla, CA 92093 (United States); Fan Xiaohui [Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721 (United States); Anderson, Scott F. [Department of Astronomy, University of Washington, Box 351580, Seattle, WA 98195 (United States); Brandt, W. N.; Schneider, Donald P. [Department of Astronomy and Astrophysics, The Pennsylvania State University, University Park, PA 16802 (United States); Plotkin, Richard M. [Astronomical Institute ' Anton Pannekoek' , University of Amsterdam, Science Park 904, NL-1098 XH Amsterdam (Netherlands); Richards, Gordon T. [Department of Physics, Drexel University, 3141 Chestnut Street, Philadelphia, PA 19104 (United States); Strauss, Michael A., E-mail: RyanLane@my.unt.edu, E-mail: ohad@unt.edu [Princeton University Observatory, Peyton Hall, Princeton, NJ 08544 (United States)

2011-12-20

We present Spitzer Space Telescope photometry of 18 Sloan Digital Sky Survey (SDSS) quasars at 2.7 {<=} z {<=} 5.9 which have weak or undetectable high-ionization emission lines in their rest-frame ultraviolet (UV) spectra (hereafter weak-lined quasars, or WLQs). The Spitzer data are combined with SDSS spectra and ground-based, near-infrared (IR) photometry of these sources to produce a large inventory of spectral energy distributions (SEDs) of WLQs across the rest-frame {approx}0.1-5 {mu}m spectral band. The SEDs of our sources are inconsistent with those of BL Lacertae objects which are dominated by synchrotron emission due to a jet aligned close to our line of sight, but are consistent with the SED of ordinary quasars with similar luminosities and redshifts that exhibit a near-to-mid-IR 'bump', characteristic of hot dust emission. This indicates that broad emission lines in WLQs are intrinsically weak, rather than suffering continuum dilution from a jet, and that such sources cannot be selected efficiently from traditional photometric surveys.

Optimal Fluorescence Waveband Determination for Detecting Defective Cherry Tomatoes Using a Fluorescence Excitation-Emission Matrix

Directory of Open Access Journals (Sweden)

In-Suck Baek

2014-11-01

Full Text Available A multi-spectral fluorescence imaging technique was used to detect defective cherry tomatoes. The fluorescence excitation and emission matrix was used to measure for defects, sound surface and stem areas to determine the optimal fluorescence excitation and emission wavelengths for discrimination. Two-way ANOVA revealed the optimal excitation wavelength for detecting defect areas was 410 nm. Principal component analysis (PCA was applied to the fluorescence emission spectra of all regions at 410 nm excitation to determine the emission wavelengths for defect detection. The major emission wavelengths were 688 nm and 506 nm for the detection. Fluorescence images combined with the determined emission wavebands demonstrated the feasibility of detecting defective cherry tomatoes with >98% accuracy. Multi-spectral fluorescence imaging has potential utility in non-destructive quality sorting of cherry tomatoes.

Study of atomic and molecular emission spectra of Sr by laser induced breakdown spectroscopy (LIBS).

Science.gov (United States)

Bhatt, Chet R; Alfarraj, Bader; Ayyalasomayajula, Krishna K; Ghany, Charles; Yueh, Fang Y; Singh, Jagdish P

2015-12-01

Laser Induced Breakdown Spectroscopy (LIBS) is an ideal analytical technique for in situ analysis of elemental composition. We have performed a comparative study of the quantitative and qualitative analysis of atomic and molecular emission from LIBS spectra. In our experiments, a mixture of SrCl2 and Al2O3 in powder form was used as a sample. The atomic emission from Sr and molecular emission from SrCl and SrO observed in LIBS spectra were analyzed. The optimum laser energies, gate delays, and gate widths for selected atomic lines and molecular bands were determined from spectra recorded at various experimental parameters. These optimum experimental conditions were used to collect calibration data, and the calibration curves were used to predict the Sr concentration. Limits of detection (LODs) for selected atomic and molecular emission spectra were determined.

Distant Determination of Bilirubin Distribution in Skin by Multi-Spectral Imaging

Science.gov (United States)

Saknite, I.; Jakovels, D.; Spigulis, J.

2011-01-01

For mapping the bilirubin distribution in bruised skin the multi-spectral imaging technique was employed, which made it possible to observe temporal changes of the bilirubin content in skin photo-types II and III. The obtained results confirm the clinical potential of this technique for skin bilirubin diagnostics.

Spectral and non-spectral interferences in the determination of thallium in environmental materials using electrothermal atomization and vaporization techniques--a case study

International Nuclear Information System (INIS)

Vale, Maria Goreti R.; Welz, Bernhard

2002-01-01

The literature on the determination of Tl in environmental samples using electrothermal atomization (ETA) and vaporization (ETV) techniques has been reviewed with special attention devoted to potential interferences and their control. Chloride interference, which is due to the formation of the volatile monochloride in the condensed phase, is the most frequently observed problem. Due to its high dissociation energy (88 kcal/mol), TlCl is difficult to dissociate in the gas phase and is easily lost. The best means of controlling this interference in ETA is atomization under isothermal conditions according to the stabilized temperature platform furnace concept, and the use of reduced palladium as a modifier. An alternative approach appears to be the 'fast furnace' concept, wherein both the use of a modifier and the pyrolysis stage are omitted. This concept requires an efficient background correction system, and high-resolution continuum-source atomic absorption spectrometry (HR-CS AAS) appears to offer the best results. This chloride interference can also cause significant problems when ETV techniques are used. Among the spectral interferences found in the determination of thallium are those due to Pd, the most efficient modifier, and Fe, which is frequently found at high concentrations in environmental samples. Both interferences are due to nearby atomic lines, and are observed only when deuterium background correction and relatively high atomization temperatures are used. A more serious spectral interference is that due to the molecular absorption spectrum of SO 2 , which has a maximum around the Tl line and exhibits a pronounced rotational fine structure. HR-CS AAS again showed the best performance in coping with this interference

Hybrid Image Fusion for Sharpness Enhancement of Multi-Spectral Lunar Images

Science.gov (United States)

Awumah, Anna; Mahanti, Prasun; Robinson, Mark

2016-10-01

Image fusion enhances the sharpness of a multi-spectral (MS) image by incorporating spatial details from a higher-resolution panchromatic (Pan) image [1,2]. Known applications of image fusion for planetary images are rare, although image fusion is well-known for its applications to Earth-based remote sensing. In a recent work [3], six different image fusion algorithms were implemented and their performances were verified with images from the Lunar Reconnaissance Orbiter (LRO) Camera. The image fusion procedure obtained a high-resolution multi-spectral (HRMS) product from the LRO Narrow Angle Camera (used as Pan) and LRO Wide Angle Camera (used as MS) images. The results showed that the Intensity-Hue-Saturation (IHS) algorithm results in a high-spatial quality product while the Wavelet-based image fusion algorithm best preserves spectral quality among all the algorithms. In this work we show the results of a hybrid IHS-Wavelet image fusion algorithm when applied to LROC MS images. The hybrid method provides the best HRMS product - both in terms of spatial resolution and preservation of spectral details. Results from hybrid image fusion can enable new science and increase the science return from existing LROC images.[1] Pohl, Cle, and John L. Van Genderen. "Review article multisensor image fusion in remote sensing: concepts, methods and applications." International journal of remote sensing 19.5 (1998): 823-854.[2] Zhang, Yun. "Understanding image fusion." Photogramm. Eng. Remote Sens 70.6 (2004): 657-661.[3] Mahanti, Prasun et al. "Enhancement of spatial resolution of the LROC Wide Angle Camera images." Archives, XXIII ISPRS Congress Archives (2016).

Measurements of the Spectral Light Emission from Decaying High Pressure Helium Plasmas

Energy Technology Data Exchange (ETDEWEB)

Stevefelt, J; Johansson, J

1971-04-15

The rate of electron density decay has been determined in a helium pulsed discharge plasma at pressures ranging from 100 to 600 Torr, primarily during the early afterglow where the electron density is from 1019 to 2 x 1017/m3. Measurements of the electrical conductivity and the absolute intensity of the light emission were made. The effective recombination rate coefficient was found to increase faster than linearly with gas pressure. The total photon emission rate was significantly lower than the effective recombination rate. Below 400 Torr pressure the afterglow was dominated by He-bands, which were related to the recombination of He{sub 2+} and He{sub 3+} ions. At higher pressures the appearance of intense lines originating from the atomic n = 3 and 23 P states is proposed to result from the He{sub 4+} recombination. Absorption measurements of the atomic metastable concentration gave evidence for recombination directly into the 23 S state. The concentration of molecular metastables was surprisingly low. The light emission had a Techi dependence, with 0 < chi < 0.35 for the intense atomic lines and 0.78 < chi < 1.10 for the molecular bands

Measurements of the Spectral Light Emission from Decaying High Pressure Helium Plasmas

International Nuclear Information System (INIS)

Stevefelt, J.; Johansson, J.

1971-04-01

The rate of electron density decay has been determined in a helium pulsed discharge plasma at pressures ranging from 100 to 600 Torr, primarily during the early afterglow where the electron density is from 10 19 to 2 x 10 17 /m 3 . Measurements of the electrical conductivity and the absolute intensity of the light emission were made. The effective recombination rate coefficient was found to increase faster than linearly with gas pressure. The total photon emission rate was significantly lower than the effective recombination rate. Below 400 Torr pressure the afterglow was dominated by He-bands, which were related to the recombination of He 2 + and He 3 + ions. At higher pressures the appearance of intense lines originating from the atomic n = 3 and 2 3 P states is proposed to result from the He 4 + recombination. Absorption measurements of the atomic metastable concentration gave evidence for recombination directly into the 2 3 S state. The concentration of molecular metastables was surprisingly low. The light emission had a T e χ dependence, with 0 < χ < 0.35 for the intense atomic lines and 0.78 < χ < 1.10 for the molecular bands

On the deviation from the sech2 superradiant emission law in a two-level atomic system

International Nuclear Information System (INIS)

Goncalves, A.E.

1990-01-01

The atomic superradiant emission is treated in the single particle mean field approximation. A single particle Hamiltonian, which represents a dressed two-level atom in a radiation field, can be obtained and it is verified that it describes the transient regime of the emission process. While the line shape emission for a bare atom follows the sech 2 law, for the dressed atom the line shape deviates appreciably from this law and it is verified that the deviation depends crucially on the ratio of the dynamic frequency shift to the transition frequency. This kind of deviation is observed in experimental results. (Author) [pt

A three-coordinate system (ecliptic, galactic, ISMF) spectral analysis of heliospheric ENA emissions using CASSINI/INCA measurements

International Nuclear Information System (INIS)

Dialynas, K.; Krimigis, S. M.; Mitchell, D. G.; Roelof, E. C.; Decker, R. B

2013-01-01

In the present study, we use all-sky energy-resolved energetic neutral atom (ENA) maps obtained by the Ion and Neutral CAmera (INCA) instrument on board Cassini that correspond to the time period from 2003 to 2009, in four discrete energy passbands (∼5.4 to ∼55 keV), to investigate the geometrical characteristics of the belt (a broad band of emission in the sky). The heliospheric ENA emissions are mapped in three different coordinate systems (ecliptic, Galactic, and interstellar magnetic field (ISMF)), and spectral analyses are performed to further examine the belt's possible energy dependence. Our conclusions are summarized as follows: (1) the high flux ENA belt identified in the energy range of 8-42 keV is moderately well organized in Galactic coordinates, as the ENA minima appear in the vicinity of the north and south Galactic poles; (2) using minimization criteria ( B · R ∼ 0), the deviation of the ENA emissions from the equator is effectively minimized in a rotated frame, which we interpret as ISMF, where its north pole points toward 190° ecliptic longitude and 15° ecliptic latitude; (3) ENA spectra show a power-law form in energy that can be fitted with a single function presenting higher spectral slopes in the belt region and lower outside (3.4 < γ < 4.4); (4) the spectra are almost indistinguishable between the tail and the nose regions, i.e., no noticeable asymmetry is observed; (5) the consistency of the ENA distributions as a function of latitude among the different INCA channels indicates that the morphology of the belt (peak, width, and structure) is nearly energy independent from 8 keV to 30 keV (minor deviations start to appear at >35 keV); and (6) in the low count rate regions, the long-term ENA count rate profiles do not match the measured cosmic ray profiles, indicating that even the minimum ENA emissions detected by INCA are foreground ENAs.

Sensitive Multi-Species Emissions Monitoring: Infrared Laser-Based Detection of Trace-Level Contaminants

Energy Technology Data Exchange (ETDEWEB)

Steill, Jeffrey D. [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Huang, Haifeng [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Hoops, Alexandra A. [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Patterson, Brian D. [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Birtola, Salvatore R. [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Jaska, Mark [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Strecker, Kevin E. [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Chandler, David W. [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Bisson, Soott [Sandia National Lab. (SNL-CA), Livermore, CA (United States)

2014-09-01

This report summarizes our development of spectroscopic chemical analysis techniques and spectral modeling for trace-gas measurements of highly-regulated low-concentration species present in flue gas emissions from utility coal boilers such as HCl under conditions of high humidity. Detailed spectral modeling of the spectroscopy of HCl and other important combustion and atmospheric species such as H 2 O, CO 2 , N 2 O, NO 2 , SO 2 , and CH 4 demonstrates that IR-laser spectroscopy is a sensitive multi-component analysis strategy. Experimental measurements from techniques based on IR laser spectroscopy are presented that demonstrate sub-ppm sensitivity levels to these species. Photoacoustic infrared spectroscopy is used to detect and quantify HCl at ppm levels with extremely high signal-to-noise even under conditions of high relative humidity. Additionally, cavity ring-down IR spectroscopy is used to achieve an extremely high sensitivity to combustion trace gases in this spectral region; ppm level CH 4 is one demonstrated example. The importance of spectral resolution in the sensitivity of a trace-gas measurement is examined by spectral modeling in the mid- and near-IR, and efforts to improve measurement resolution through novel instrument development are described. While previous project reports focused on benefits and complexities of the dual-etalon cavity ring-down infrared spectrometer, here details on steps taken to implement this unique and potentially revolutionary instrument are described. This report also illustrates and critiques the general strategy of IR- laser photodetection of trace gases leading to the conclusion that mid-IR laser spectroscopy techniques provide a promising basis for further instrument development and implementation that will enable cost-effective sensitive detection of multiple key contaminant species simultaneously.

Reliability Study of Mechatronic Power Components Using Spectral Photon Emission Microscopy

Directory of Open Access Journals (Sweden)

N. Moultif

2016-11-01

Full Text Available In this paper, we present one of the most important failure analysis tools that permits the localizing and the identification of the failure mechanisms. It is a new spectral photon emission system, enabling to localize the failure, and quickly get the photon emission spectra that characterize the failure with high resolution. A diffraction grating is used as a spectrometer in the system. Application results on mechatronic power devices such as HEMT AlGaN/GAN and SiC MOSFETs are reported.

A comparison of multi-spectral, multi-angular, and multi-temporal remote sensing datasets for fractional shrub canopy mapping in Arctic Alaska

Science.gov (United States)

Selkowitz, D.J.

2010-01-01

Shrub cover appears to be increasing across many areas of the Arctic tundra biome, and increasing shrub cover in the Arctic has the potential to significantly impact global carbon budgets and the global climate system. For most of the Arctic, however, there is no existing baseline inventory of shrub canopy cover, as existing maps of Arctic vegetation provide little information about the density of shrub cover at a moderate spatial resolution across the region. Remotely-sensed fractional shrub canopy maps can provide this necessary baseline inventory of shrub cover. In this study, we compare the accuracy of fractional shrub canopy (> 0.5 m tall) maps derived from multi-spectral, multi-angular, and multi-temporal datasets from Landsat imagery at 30 m spatial resolution, Moderate Resolution Imaging SpectroRadiometer (MODIS) imagery at 250 m and 500 m spatial resolution, and MultiAngle Imaging Spectroradiometer (MISR) imagery at 275 m spatial resolution for a 1067 km2 study area in Arctic Alaska. The study area is centered at 69 ??N, ranges in elevation from 130 to 770 m, is composed primarily of rolling topography with gentle slopes less than 10??, and is free of glaciers and perennial snow cover. Shrubs > 0.5 m in height cover 2.9% of the study area and are primarily confined to patches associated with specific landscape features. Reference fractional shrub canopy is determined from in situ shrub canopy measurements and a high spatial resolution IKONOS image swath. Regression tree models are constructed to estimate fractional canopy cover at 250 m using different combinations of input data from Landsat, MODIS, and MISR. Results indicate that multi-spectral data provide substantially more accurate estimates of fractional shrub canopy cover than multi-angular or multi-temporal data. Higher spatial resolution datasets also provide more accurate estimates of fractional shrub canopy cover (aggregated to moderate spatial resolutions) than lower spatial resolution datasets

Analysis of Spectral Features of Seawaterbiooptical Components Fluorescence from the Excitation-emission Matrix

Science.gov (United States)

Salyuk, P. A.; Nagorny, I. G.

The paper presents the method for processing of excitation-emission matrix of sea water and the allocation of the spectral characteristics of different types of colored dissolved organic matter (CDOM) and phytoplankton cells in seawater. The method consists of identification of regularly observed fluorescence peaks of CDOM in marine waters of different type and definition of the spectral ranges, where the predominant influence of these peaks are observed.

Multielement determination of rare earth elements by liquid chromatography/inductively coupled plasma atomic emission spectrometry

International Nuclear Information System (INIS)

Sawatari, Hideyuki; Asano, Takaaki; Hu, Xincheng; Saizuka, Tomoo; Itoh, Akihide; Hirose, Akio; Haraguchi, Hiroki

1995-01-01

The rapid determination of rare earth elements (REEs) has been investigated by an on-line system of high performance liquid chromatography/multichannel inductively coupled plasma atomic emission spectrometry. In the present system, all REEs could be detected simultaneously in a single chromatographic measurement without spectral interferences. Utilizing a cation exchange column and 2-hydroxy-2-methylpropanoic acid aqueous solution as the mobile phase, the detection limits of 0.4-30 ng ml -1 for all REEs were obtained. The system was applied to the determination of REEs in geological standard rock samples and rare earth impurities in high purity rare earth oxides. The REEs in standard rocks could be determined by the present HPLC/ICP-AES system without pretreatment after acid digestion, although the detection limits were not sufficient for the analysis of rare earth oxides. (author)

Investigation of an alternating current plasma as an element selective atomic emission detector for high-resolution capillary gas chromatography and as a source for atomic absorption and atomic emission spectrometry

Science.gov (United States)

Ombaba, Jackson M.

This thesis deals with the construction and evaluation of an alternating current plasma (ACP) as an element-selective detector for high resolution capillary gas chromatography (GC) and as an excitation source for atomic absorption spectrometry (AAS) and atomic emission spectrometry (AES). The plasma, constrained in a quartz discharge tube at atmospheric pressure, is generated between two copper electrodes and utilizes helium as the plasma supporting gas. The alternating current plasma power source consists of a step-up transformer with a secondary output voltage of 14,000 V at a current of 23 mA. The device exhibits a stable signal because the plasma is self-seeding and reignites itself every half cycle. A tesla coil is not required to commence generation of the plasma if the ac voltage applied is greater than the breakdown voltage of the plasma-supporting gas. The chromatographic applications studied included the following: (1) the separation and selective detection of the organotin species, tributyltin chloride (TBT) and tetrabutyltin (TEBT), in environmental matrices including mussels (Mvutilus edullus) and sediment from Boston Harbor, industrial waste water and industrial sludge, and (2) the detection of methylcyclopentadienyl manganesetricarbonyl (MMT) and similar compounds used as gasoline additives. An ultrasonic nebulizer (common room humidifier) was utilized as a sample introduction device for aqueous solutions when the ACP was employed as an atomization source for atomic absorption spectrometry and as an excitation source for atomic emission spectrometry. Plasma diagnostic parameters studied include spatial electron number density across the discharge tube, electronic, excitation and ionization temperatures. Interference studies both in absorption and emission modes were also considered. Figures of merits of selected elements both in absorption and emission modes are reported. The evaluation of a computer-aided optimization program, Drylab GC, using

Using the van der Waals broadening of spectral atomic lines to measure the gas temperature of an argon-helium microwave plasma at atmospheric pressure

International Nuclear Information System (INIS)

Munoz, J.; Dimitrijevic, M.S.; Yubero, C.; Calzada, M.D.

2009-01-01

The applications of plasmas generated with gas mixtures have become increasingly common in different scientific and technological fields. In order to understand the advantages of these discharges, for instance in chemical analysis, it is necessary to know the gas temperature (T g , kinetic energy of the heavy particles) since it has a great influence on the atomization reactions of the molecules located in the discharge, along with the dependence of the reaction rate on this parameter. The ro-vibrational emission spectra of the molecular species are usually used to measure the gas temperature of a discharge at atmospheric pressure although under some experimental conditions, these are difficult to detect. In such cases, the gas temperature can be determined from the van der Waals broadening of the emitted atomic spectral lines related to this parameter. The method proposed is based on the van der Waals broadening taking into account two perturbers

Multi-Temporal vs. Hyper-Spectral Imaging for Future Land Imaging at 30 m

Data.gov (United States)

National Aeronautics and Space Administration — We propose to determine the information content of multi-temporal land imaging in discrete Landsat-like spectral bands at 30 m with a 360 km swath width and compare...

Infrared normal spectral emissivity of Ti-6Al-4V alloy in the 500-1150 K temperature range

Energy Technology Data Exchange (ETDEWEB)

Gonzalez-Fernandez, L. [Departamento de Fisica de la Materia Condensada, Facultad de Ciencia y Tecnologia, Universidad del Pais Vasco, Barrio Sarriena s/n, 48940 Leioa, Bizkaia (Spain); Industria de Turbo Propulsores, S.A., Planta de Zamudio, Edificio 300, 48170 Zamudio, Bizkaia (Spain); Risueno, E. [CIC Energigune, Parque Tecnologico, Albert Einstein 48, 01510 Minano, Alava, Spain. (Spain); Perez-Saez, R.B., E-mail: raul.perez@ehu.es [Departamento de Fisica de la Materia Condensada, Facultad de Ciencia y Tecnologia, Universidad del Pais Vasco, Barrio Sarriena s/n, 48940 Leioa, Bizkaia (Spain); Instituto de Sintesis y Estudio de Materiales, Universidad del Pais Vasco, Apdo. 644,48080 Bilbao, Spain. (Spain); Tello, M.J. [Departamento de Fisica de la Materia Condensada, Facultad de Ciencia y Tecnologia, Universidad del Pais Vasco, Barrio Sarriena s/n, 48940 Leioa, Bizkaia (Spain); Instituto de Sintesis y Estudio de Materiales, Universidad del Pais Vasco, Apdo. 644,48080 Bilbao, Spain. (Spain)

2012-11-15

Highlights: Black-Right-Pointing-Pointer First heating cycle acts as a annealing, relieving the surface stresses. Black-Right-Pointing-Pointer Stress relieving occurs mainly above 900 K. Black-Right-Pointing-Pointer Emissivity decreases between 0.35 and 0.10 in the 2.5-22 {mu}m spectral range. Black-Right-Pointing-Pointer Emissivity increases linearly with temperature, with the same slope for {lambda} > 10 {mu}m. Black-Right-Pointing-Pointer Good agreement between resistivity and emissivity by means of Hagen-Rubens relation. - Abstract: Thermal radiative emissivity is related to the optical and electrical properties of materials, and it is a key parameter required in a large number of industrial applications. In the case of Ti-6Al-4V, spectral emissivity experimental data are not available for the range of temperatures between 400 and 1200 K, where almost all industrial applications take place. The experimental results in this paper show that the normal spectral emissivity decreases with wavelength from a value of about 0.35 at 2.5 {mu}m to about 0.10 at 22 {mu}m. At the same time, the spectral emissivity shows a slight linear increase with temperature between 500 and 1150 K, with approximately the same slope for all wavelengths. Additionally, the influence of the samples thermal history on the emissivity is studied. A strong decrease in the emissivity values appears due to the effect of surface stress relaxation processes. This means that the radiative properties of this alloy strongly depend on the surface stress state. A thermal treatment to relieve the surface stress should be carried out to achieve a steady state of the radiative properties. In addition, a good qualitative agreement is found between the temperature dependence of the electrical resistivity obtained using conventional measurements and the one obtained from the emissivity experimental results by using the Hagen-Rubens equation.

Quantitative functional optical imaging of the human skin using multi-spectral imaging

International Nuclear Information System (INIS)

Kainerstorfer, J. M.

2010-01-01

Light tissue interactions can be described by the physical principles of absorption and scattering. Based on those parameters, different tissue types and analytes can be distinguished. Extracting blood volume and oxygenation is of particular interest in clinical routines for tumor diagnostics and treatment follow up, since they are parameters of angiogenic processes. The quantification of those analytes in tissue can be done by physical modeling of light tissue interaction. The physical model used here is the random walk theory. However, for quantification and clinical usefulness, one has to account for multiple challenges. First, one must consider the effect of topology of the sample on measured physical parameters. Second, diffusion of light inside the tissue is dependent on the structure of the sample imaged. Thus, the structural conformation has to be taken into account. Third, clinical translation of imaging modalities is often hindered due to the complicated post-processing of data, not providing results in real-time. In this thesis, two imaging modalities are being utilized, where the first one, diffuse multi-spectral imaging, is based on absorption contrast and spectral characteristics and the second one, Optical Coherence Tomography (OCT), is based on scattering changes within the tissue. Multi-spectral imaging can provide spatial distributions of blood volume and blood oxygenation and OCT yields 3D structural images with micrometer resolution. In order to address the challenges mentioned above, a curvature correction algorithm for taking the topology into account was developed. Without taking curvature of the object into account, reconstruction of optical properties is not accurate. The method developed removes this artifact and recovers the underlying data, without the necessity of measuring the object's shape. The next step was to recover blood volume and oxygenation values in real time. Principal Component Analysis (PCA) on multi spectral images is

Improving the Ni I atomic model for solar and stellar atmospheric models

International Nuclear Information System (INIS)

Vieytes, M. C.; Fontenla, J. M.

2013-01-01

Neutral nickel (Ni I) is abundant in the solar atmosphere and is one of the important elements that contribute to the emission and absorption of radiation in the spectral range between 1900 and 3900 Å. Previously, the Solar Radiation Physical Modeling (SRPM) models of the solar atmosphere only considered a few levels of this species. Here, we improve the Ni I atomic model by taking into account 61 levels and 490 spectral lines. We compute the populations of these levels in full NLTE using the SRPM code and compare the resulting emerging spectrum with observations. The present atomic model significantly improves the calculation of the solar spectral irradiance at near-UV wavelengths, which is important for Earth atmospheric studies, and particularly for ozone chemistry.

Improving the Ni I atomic model for solar and stellar atmospheric models

Energy Technology Data Exchange (ETDEWEB)

Vieytes, M. C. [Instituto de de Astronomía y Física del Espacio, CONICET and UNTREF, Buenos Aires (Argentina); Fontenla, J. M., E-mail: mariela@iafe.uba.ar, E-mail: johnf@digidyna.com [North West Research Associates, 3380 Mitchell Lane, Boulder, CO 80301 (United States)

2013-06-01

Neutral nickel (Ni I) is abundant in the solar atmosphere and is one of the important elements that contribute to the emission and absorption of radiation in the spectral range between 1900 and 3900 Å. Previously, the Solar Radiation Physical Modeling (SRPM) models of the solar atmosphere only considered a few levels of this species. Here, we improve the Ni I atomic model by taking into account 61 levels and 490 spectral lines. We compute the populations of these levels in full NLTE using the SRPM code and compare the resulting emerging spectrum with observations. The present atomic model significantly improves the calculation of the solar spectral irradiance at near-UV wavelengths, which is important for Earth atmospheric studies, and particularly for ozone chemistry.

A Concept of Multi-Mode High Spectral Resolution Lidar Using Mach-Zehnder Interferometer

Directory of Open Access Journals (Sweden)

Jin Yoshitaka

2016-01-01

Full Text Available In this paper, we present the design of a High Spectral Resolution Lidar (HSRL using a laser that oscillates in a multi-longitudinal mode. Rayleigh and Mie scattering components are separated using a Mach-Zehnder Interferometer (MZI with the same free spectral range (FSR as the transmitted laser. The transmitted laser light is measured as a reference signal with the same MZI. By scanning the MZI periodically with a scanning range equal to the mode spacing, we can identify the maximum Mie and the maximum Rayleigh signals using the reference signal. The cross talk due to the spectral width of each laser mode can also be estimated.

Study of multi-level atomic systems with the application of magnetic field

Science.gov (United States)

Hu, Jianping; Roy, Subhankar; Ummal Momeen, M.

2018-04-01

The complexity of multiple energy levels associated with each atomic system determines the various processes related to light- matter interactions. It is necessary to understand the influence of different levels in a given atomic system. In this work we focus on multi- level atomic schemes with the application of magnetic field. We analyze the different EIT windows which appears in the presence of moderately high magnetic field (∼ 10 G) strength.

Directional Canopy Emissivity Estimation Based on Spectral Invariants

Science.gov (United States)

Guo, M.; Cao, B.; Ren, H.; Yongming, D.; Peng, J.; Fan, W.

2017-12-01

Land surface emissivity is a crucial parameter for estimating land surface temperature from remote sensing data and also plays an important role in the physical process of surface energy and water balance from local to global scales. To our knowledge, the emissivity varies with surface type and cover. As for the vegetation, its canopy emissivity is dependent on vegetation types, viewing zenith angle and structure that changes in different growing stages. Lots of previous studies have focused on the emissivity model, but few of them are analytic and suited to different canopy structures. In this paper, a new physical analytic model is proposed to estimate the directional emissivity of homogenous vegetation canopy based on spectral invariants. The initial model counts the directional absorption in six parts: the direct absorption of the canopy and the soil, the absorption of the canopy and soil after a single scattering and after multiple scattering within the canopy-soil system. In order to analytically estimate the emissivity, the pathways of photons absorbed in the canopy-soil system are traced using the re-collision probability in Fig.1. After sensitive analysis on the above six absorptions, the initial complicated model was further simplified as a fixed mathematic expression to estimate the directional emissivity for vegetation canopy. The model was compared with the 4SAIL model, FRA97 model, FRA02 model and DART model in Fig.2, and the results showed that the FRA02 model is significantly underestimated while the FRA97 model is a little underestimated, on basis of the new model. On the contrary, the emissivity difference between the new model with the 4SAIL model and DART model was found to be less than 0.002. In general, since the new model has the advantages of mathematic expression with accurate results and clear physical meaning, the model is promising to be extended to simulate the directional emissivity for the discrete canopy in further study.

Absorption properties of identical atoms

International Nuclear Information System (INIS)

Sancho, Pedro

2013-01-01

Emission rates and other optical properties of multi-particle systems in collective and entangled states differ from those in product ones. We show the existence of similar effects in the absorption probabilities for (anti)symmetrized states of two identical atoms. The effects strongly depend on the overlapping between the atoms and differ for bosons and fermions. We propose a viable experimental verification of these ideas. -- Highlights: •The absorption rates of a pair of identical atoms in product and (anti)symmetrized states are different. •The modifications of the optical properties are essentially determined by the overlapping between the atoms. •The absorption properties differ, in some cases, for bosons and fermions

Spectral anomalies of the effect of light-induced drift of caesium atoms caused by the velocity dependence of transport collision frequencies

Energy Technology Data Exchange (ETDEWEB)

Parkhomenko, A I [Institute of Automation and Electrometry, Siberian Branch of the Russian Academy of Sciences, Novosibirsk (Russian Federation); Shalagin, A M [Novosibirsk State University, Novosibirsk (Russian Federation)

2014-10-31

The spectral features of the light-induced drift (LID) velocity of caesium atoms in inert buffer gases are studied theoretically. A strong temperature dependence of the spectral LID line shape of Cs atoms in Ar or Kr atmosphere in the vicinity of T ∼ 1000 K is predicted. It is shown that the anomalous LID of Cs atoms in binary buffer mixtures of two different inert gases can be observed at virtually any (including ambient) temperature, depending on the content of the components in these mixtures. The results obtained make it possible to precisely test the interatomic interaction potentials in the experiments on the anomalous LID. (quantum optics)

Spontaneous emission spectrum of a four-level atom coupled by three kinds of reservoirs

International Nuclear Information System (INIS)

Yang Dong; Wang Jian; Zhang, Hanzhuang; Yao Jinbo

2007-01-01

A model of a four-level atom embedded in a double-band photonic crystal (PC) is presented. The atomic transitions from the upper two levels to the lower two levels are coupled by the same reservoir which is assumed in turn to be isotropic PC modes, anisotropic PC modes and free vacuum modes. The effects of the fine structure of the atomic ground state levels and the quantum interference on the spontaneous emission spectrum of an atom are investigated in detail. Most interestingly, it is shown for the first time that new spontaneous emission lines are produced from the fine splitting of atomic ground state levels in the isotropic PC case. Quantum interference induces additional narrow spontaneous lines near the transition from the empty upper level to the lower levels

Terahertz detectors for long wavelength multi-spectral imaging.

Energy Technology Data Exchange (ETDEWEB)

Lyo, Sungkwun Kenneth; Wanke, Michael Clement; Reno, John Louis; Shaner, Eric Arthur; Grine, Albert D.

2007-10-01

The purpose of this work was to develop a wavelength tunable detector for Terahertz spectroscopy and imaging. Our approach was to utilize plasmons in the channel of a specially designed field-effect transistor called the grating-gate detector. Grating-gate detectors exhibit narrow-linewidth, broad spectral tunability through application of a gate bias, and no angular dependence in their photoresponse. As such, if suitable sensitivity can be attained, they are viable candidates for Terahertz multi-spectral focal plane arrays. When this work began, grating-gate gate detectors, while having many promising characteristics, had a noise-equivalent power (NEP) of only 10{sup -5} W/{radical}Hz. Over the duration of this project, we have obtained a true NEP of 10{sup -8} W/{radical}Hz and a scaled NEP of 10{sup -9}W/{radical}Hz. The ultimate goal for these detectors is to reach a NEP in the 10{sup -9{yields}-10}W/{radical}Hz range; we have not yet seen a roadblock to continued improvement.

Spectrally resolved pressure dependence measurements of air fluorescence emission with AIRFLY

International Nuclear Information System (INIS)

Ave, M.; Bohacova, M.; Buonomo, B.; Busca, N.; Cazon, L.; Chemerisov, S.D.; Conde, M.E.; Crowell, R.A.; Di Carlo, P.; Di Giulio, C.; Doubrava, M.; Esposito, A.; Facal, P.; Franchini, F.J.; Hoerandel, J.; Hrabovsky, M.; Iarlori, M.; Kasprzyk, T.E.; Keilhauer, B.; Klages, H.

2008-01-01

The knowledge of the fluorescence emission as a function of atmospheric parameters is essential for the detection of extensive air showers with the fluorescence technique. In this paper, we summarize AIRFLY published measurements of the pressure dependence of the fluorescence yield. The spectral distribution of the fluorescent light between 280 and 429 nm has been measured with high resolution. Relative intensities of 34 spectral lines have been determined. The pressure dependence of 25 lines was measured in terms of quenching reference pressures p λ ' in air. This set of AIRFLY measurements yields the most comprehensive parametrization of the pressure dependence of the fluorescent spectrum.

The Combined ASTER MODIS Emissivity over Land (CAMEL Part 1: Methodology and High Spectral Resolution Application

Directory of Open Access Journals (Sweden)

E. Eva Borbas

2018-04-01

Full Text Available As part of a National Aeronautics and Space Administration (NASA MEaSUREs (Making Earth System Data Records for Use in Research Environments Land Surface Temperature and Emissivity project, the Space Science and Engineering Center (UW-Madison and the NASA Jet Propulsion Laboratory (JPL developed a global monthly mean emissivity Earth System Data Record (ESDR. This new Combined ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer and MODIS (Moderate Resolution Imaging Spectroradiometer Emissivity over Land (CAMEL ESDR was produced by merging two current state-of-the-art emissivity datasets: the UW-Madison MODIS Infrared emissivity dataset (UW BF and the JPL ASTER Global Emissivity Dataset Version 4 (GEDv4. The dataset includes monthly global records of emissivity and related uncertainties at 13 hinge points between 3.6–14.3 µm, as well as principal component analysis (PCA coefficients at 5-km resolution for the years 2000 through 2016. A high spectral resolution (HSR algorithm is provided for HSR applications. This paper describes the 13 hinge-points combination methodology and the high spectral resolutions algorithm, as well as reports the current status of the dataset.

Spectral emissivity measurements of candidate materials for very high temperature reactors

Energy Technology Data Exchange (ETDEWEB)

Cao, G.; Weber, S.J.; Martin, S.O.; Anderson, M.H. [Department of Engineering Physics, University of Wisconsin, 1500 Engineering Drive, Madison, WI (United States); Sridharan, K., E-mail: kumars@cae.wisc.edu [Department of Engineering Physics, University of Wisconsin, 1500 Engineering Drive, Madison, WI (United States); Allen, T.R. [Department of Engineering Physics, University of Wisconsin, 1500 Engineering Drive, Madison, WI (United States)

2012-10-15

Heat dissipation by radiation is an important consideration in VHTR components, particularly the reactor pressure vessel (RPV), because of the fourth power temperature dependence of radiated heat. Since emissivity is the material property that dictates the ability to radiate heat, measurements of emissivities of materials that are being specifically considered for the construction of VHTR become important. Emissivity is a surface phenomenon and therefore compositional, structural, and topographical changes that occur at the surfaces of these materials as a result of their interactions with the environment at high temperatures will alter their emissivities. With this background, an experimental system for the measurement of spectral emissivity has been designed and constructed. The system has been calibrated in conformance with U.S. DoE quality assurance standards using inert ceramic materials, boron nitride, silicon carbide, and aluminum oxide. The results of high temperature emissivity measurements of potential VHTR materials such as ferritic steels SA 508, T22, T91 and austenitic alloys IN 800H, Haynes 230, IN 617, and 316 stainless steel have been presented.

Measurement of multilayer mirror reflectivity and stimulated emission in the XUV spectral region

International Nuclear Information System (INIS)

Keane, C.; Nam, C.H.; Meixler, L.; Milchberg, H.; Skinner, C.H.; Suckewer, S.; Voorhees, D.; Barbee, T.

1986-03-01

We present measurements of multilayer mirror reflectivity and stimulated emission in the XUV spectral region. A molybdenum-silicon multilayer mirror with 12% measured reflectivity at 182 A was found to produce a 120% enhancement of the C VI 182 A line (3 → 2 transition) in a strongly recombining plasma. No such enhancement of the CV 186.7 A line was seen, demonstrating amplification of stimulated emission at 182 A

Laser-Induced Breakdown Spectroscopy Infrared Emission From Inorganic and Organic Substances

National Research Council Canada - National Science Library

Yang, C.S; Brown, E; Hommerich, U; Trivedi, S. B; Snyder, A. P; Samuels, A. C

2006-01-01

Laser-induced breakdown spectroscopy (LIBS) has been established as a powerful method for identifying trace elemental contaminants by analyzing the atomic spectral emission lines that result subsequent to plasmas generated by laser power...

MULTI-TEMPORAL ASSESSMENT OF LYCHEE TREE CROP STRUCTURE USING MULTI-SPECTRAL RPAS IMAGERY

Directory of Open Access Journals (Sweden)

K. Johansen

2017-08-01

Full Text Available The lychee tree is native to China and produce small fleshy fruit up to 5 cm in diameter. Lychee production in Australia is worth > $20 million annually. Pruning of trees encourages new growth, has a positive effect on fruiting of lychee, makes fruit-picking easier, and may increase yield, as it increases light interception and tree crown surface area. The objective of this research was to assess changes in tree structure, i.e. tree crown circumference, width, height and Plant Projective Cover (PPC using multi-spectral Remotely Piloted Aircraft System (RPAS imagery collected before and after pruning of a lychee plantation. A secondary objective was to assess any variations in the results as a function of various flying heights (30, 50 and 70 m. Pre- and post-pruning results showed significant differences in all measured tree structural parameters, including an average decrease in: tree crown circumference of 1.94 m; tree crown width of 0.57 m; tree crown height of 0.62 m; and PPC of 14.8 %. The different flying heights produced similar measurements of tree crown width and PPC, whereas tree crown circumference and height measurements decreased with increasing flying height. These results show that multi-spectral RPAS imagery can provide a suitable means of assessing pruning efforts undertaken by contractors based on changes in tree structure of lychee plantations and that it is important to collect imagery in a consistent manner, as varying flying heights may cause changes to tree structural measurements.

Sub-microanalysis of solid samples with near-field enhanced atomic emission spectroscopy

Science.gov (United States)

Wang, Xiaohua; Liang, Zhisen; Meng, Yifan; Wang, Tongtong; Hang, Wei; Huang, Benli

2018-03-01

A novel approach, which we have chosen to name it as near-field enhanced atomic emission spectroscopy (NFE-AES), was proposed by introducing a scanning tunnelling microscope (STM) system into a laser-induced breakdown spectrometry (LIBS). The near-field enhancement of a laser-illuminated tip was utilized to improve the lateral resolution tremendously. Using the hybrid arrangement, pure metal tablets were analyzed to verify the performance of NFE-AES both in atmosphere and in vacuum. Due to localized surface plasmon resonance (LSPR), the incident electromagnetic field is enhanced and confined at the apex of tip, resulting in sub-micron scale ablation and elemental emission signal. We discovered that the signal-to-noise ratio (SNR) and the spectral resolution obtained in vacuum condition are better than those acquired in atmospheric condition. The quantitative capability of NFE-AES was demonstrated by analyzing Al and Pb in Cu matrix, respectively. Submicron-sized ablation craters were achieved by performing NFE-AES on a Si wafer with an Al film, and the spectroscopic information from a crater of 650 nm diameter was successfully obtained. Due to its advantage of high lateral resolution, NFE-AES imaging of micro-patterned Al lines on an integrated circuit of a SIM card was demonstrated with a sub-micron lateral resolution. These results reveal the potential of the NFE-AES technique in sub-microanalysis of solids, opening an opportunity to map chemical composition at sub-micron scale.

The cathode-fall of low-pressure hydrogen discharges: Absolute spectral emission and model

Energy Technology Data Exchange (ETDEWEB)

Jelenkovic, B. M. [JILA, National Institute of Standards and Technology and University of Colorado Boulder, Boulder, Colorado 80309-0440 (United States); Institute of Physics, University of Belgrade, Pregrevica 118, 11080 Zenum Belgrade (Serbia); Phelps, A. V. [JILA, National Institute of Standards and Technology and University of Colorado Boulder, Boulder, Colorado 80309-0440 (United States)

2011-10-15

Absolute excitation probabilities from very low to moderate-current hydrogen discharges in parallel-plane geometry are measured and used to test models. Relative emission data are obtained for the H{sub {alpha}} line, the H{sub 2} (a{sup 3}{Sigma}{yields}b{sup 3}{Pi}) near-UV continuum, and the H{sub 2} (G{sup 1}{Sigma}{yields}B{sup 1}{Pi}{sub u}{sup +}) band at pressures of 0.5 and 2 Torr, a 1.05 cm gap, and voltages from 300 to 900 V. Electron behavior is traced using the first negative (A{sup 2}{Sigma}{sub g}{yields} X{sup 2}{Pi}{sub u}, {nu}'' = 0 {yields}{nu}' = 0) band of N{sub 2}{sup +} by adding 2% N{sub 2}. Relative measurements of H{sub {alpha}}, H{sub 2} near-UV, and N{sub 2} 1st negative emission are placed on a absolute scale by normalization to published measurements and Boltzmann calculations of electron excitation. Emission probabilities calculated using a multi-beam kinetics model for the electrons, H{sup +}, H{sub 2}{sup +}, H{sub 3}{sup +}, H{sup -}, H, and H{sub 2} are compared with the calibrated experiments. Fast H atoms are calculated to produce H{sub {alpha}} excitation that is comparable with that of electrons. The calculated emission intensities for H{sub {alpha}} and H{sub 2} near-UV continuum are within a factor of three of the absolute measurements for a range of 5000:1 in current and 4:1 in hydrogen pressure. Calculations at 2 Torr show that most of the space charge electric field responsible for the cathode fall is produced by H{sub 3}{sup +} ions.

Teleporting the one-qubit state via two-level atoms with spontaneous emission

Energy Technology Data Exchange (ETDEWEB)

Hu Mingliang, E-mail: mingliang0301@xupt.edu.cn, E-mail: mingliang0301@163.com [School of Science, Xi' an University of Posts and Telecommunications, Xi' an 710061 (China)

2011-05-14

We study quantum teleportation via two two-level atoms coupled collectively to a multimode vacuum field and prepared initially in different atomic states. We concentrated on the influence of the spontaneous emission, collective damping and dipole-dipole interaction of the atoms on fidelity dynamics of quantum teleportation and obtained the region of spatial distance between the two atoms over which the state can be teleported nonclassically. Moreover, we showed through concrete examples that entanglement of the channel state is the prerequisite but not the only essential quantity for predicting the teleportation fidelity.

Multi-layer imager design for mega-voltage spectral imaging

Science.gov (United States)

Myronakis, Marios; Hu, Yue-Houng; Fueglistaller, Rony; Wang, Adam; Baturin, Paul; Huber, Pascal; Morf, Daniel; Star-Lack, Josh; Berbeco, Ross

2018-05-01

The architecture of multi-layer imagers (MLIs) can be exploited to provide megavoltage spectral imaging (MVSPI) for specific imaging tasks. In the current work, we investigated bone suppression and gold fiducial contrast enhancement as two clinical tasks which could be improved with spectral imaging. A method based on analytical calculations that enables rapid investigation of MLI component materials and thicknesses was developed and validated against Monte Carlo computations. The figure of merit for task-specific imaging performance was the contrast-to-noise ratio (CNR) of the gold fiducial when the CNR of bone was equal to zero after a weighted subtraction of the signals obtained from each MLI layer. Results demonstrated a sharp increase in the CNR of gold when the build-up component or scintillation materials and thicknesses were modified. The potential for low-cost, prompt implementation of specific modifications (e.g. composition of the build-up component) could accelerate clinical translation of MVSPI.

Effect of atomic initial phase difference on spontaneous emission of an atom embedded in photonic crystal

International Nuclear Information System (INIS)

Bing, Zhang; Xiu-Dong, Sun; Xiang-Qian, Jiang

2010-01-01

We investigate the effect of initial phase difference between the two excited states of a V-type three-level atom on its steady state behaviour of spontaneous emission. A modified density of modes is introduced to calculate the spontaneous emission spectra in photonic crystal. Spectra in free space are also shown to compare with that in photonic crystal with different relative positions of the excited levels from upper band-edge frequency. It is found that the initial phase difference plays an important role in the quantum interference property between the two decay channels. For a zero initial phase, destructive property is presented in the spectra. With the increase of initial phase difference, quantum interference between the two decay channels from upper levels to ground level turns to be constructive. Furthermore, we give an interpretation for the property of these spectra. (atomic and molecular physics)

Infrared normal spectral emissivity of Ti–6Al–4V alloy in the 500–1150 K temperature range

International Nuclear Information System (INIS)

González-Fernández, L.; Risueño, E.; Pérez-Sáez, R.B.; Tello, M.J.

2012-01-01

Highlights: ► First heating cycle acts as a annealing, relieving the surface stresses. ► Stress relieving occurs mainly above 900 K. ► Emissivity decreases between 0.35 and 0.10 in the 2.5–22 μm spectral range. ► Emissivity increases linearly with temperature, with the same slope for λ > 10 μm. ► Good agreement between resistivity and emissivity by means of Hagen–Rubens relation. - Abstract: Thermal radiative emissivity is related to the optical and electrical properties of materials, and it is a key parameter required in a large number of industrial applications. In the case of Ti–6Al–4V, spectral emissivity experimental data are not available for the range of temperatures between 400 and 1200 K, where almost all industrial applications take place. The experimental results in this paper show that the normal spectral emissivity decreases with wavelength from a value of about 0.35 at 2.5 μm to about 0.10 at 22 μm. At the same time, the spectral emissivity shows a slight linear increase with temperature between 500 and 1150 K, with approximately the same slope for all wavelengths. Additionally, the influence of the samples thermal history on the emissivity is studied. A strong decrease in the emissivity values appears due to the effect of surface stress relaxation processes. This means that the radiative properties of this alloy strongly depend on the surface stress state. A thermal treatment to relieve the surface stress should be carried out to achieve a steady state of the radiative properties. In addition, a good qualitative agreement is found between the temperature dependence of the electrical resistivity obtained using conventional measurements and the one obtained from the emissivity experimental results by using the Hagen–Rubens equation.

Measurement of fluorescence emission spectrum of few strongly driven atoms using an optical nanofiber.

Science.gov (United States)

Das, Manoj; Shirasaki, A; Nayak, K P; Morinaga, M; Le Kien, Fam; Hakuta, K

2010-08-02

We show that the fluorescence emission spectrum of few atoms can be measured by using an optical nanofiber combined with the optical heterodyne and photon correlation spectroscopy. The observed fluorescence spectrum of the atoms near the nanofiber shows negligible effects of the atom-surface interaction and agrees well with the Mollow triplet spectrum of free-space atoms at high excitation intensity.

Using Non-Invasive Multi-Spectral Imaging to Quantitatively Assess Tissue Vasculature

Energy Technology Data Exchange (ETDEWEB)

Vogel, A; Chernomordik, V; Riley, J; Hassan, M; Amyot, F; Dasgeb, B; Demos, S G; Pursley, R; Little, R; Yarchoan, R; Tao, Y; Gandjbakhche, A H

2007-10-04

This research describes a non-invasive, non-contact method used to quantitatively analyze the functional characteristics of tissue. Multi-spectral images collected at several near-infrared wavelengths are input into a mathematical optical skin model that considers the contributions from different analytes in the epidermis and dermis skin layers. Through a reconstruction algorithm, we can quantify the percent of blood in a given area of tissue and the fraction of that blood that is oxygenated. Imaging normal tissue confirms previously reported values for the percent of blood in tissue and the percent of blood that is oxygenated in tissue and surrounding vasculature, for the normal state and when ischemia is induced. This methodology has been applied to assess vascular Kaposi's sarcoma lesions and the surrounding tissue before and during experimental therapies. The multi-spectral imaging technique has been combined with laser Doppler imaging to gain additional information. Results indicate that these techniques are able to provide quantitative and functional information about tissue changes during experimental drug therapy and investigate progression of disease before changes are visibly apparent, suggesting a potential for them to be used as complementary imaging techniques to clinical assessment.

Multi-spectral CCD camera system for ocean water color and seacoast observation

Science.gov (United States)

Zhu, Min; Chen, Shiping; Wu, Yanlin; Huang, Qiaolin; Jin, Weiqi

2001-10-01

One of the earth observing instruments on HY-1 Satellite which will be launched in 2001, the multi-spectral CCD camera system, is developed by Beijing Institute of Space Mechanics & Electricity (BISME), Chinese Academy of Space Technology (CAST). In 798 km orbit, the system can provide images with 250 m ground resolution and a swath of 500 km. It is mainly used for coast zone dynamic mapping and oceanic watercolor monitoring, which include the pollution of offshore and coast zone, plant cover, watercolor, ice, terrain underwater, suspended sediment, mudflat, soil and vapor gross. The multi- spectral camera system is composed of four monocolor CCD cameras, which are line array-based, 'push-broom' scanning cameras, and responding for four spectral bands. The camera system adapts view field registration; that is, each camera scans the same region at the same moment. Each of them contains optics, focal plane assembly, electrical circuit, installation structure, calibration system, thermal control and so on. The primary features on the camera system are: (1) Offset of the central wavelength is better than 5 nm; (2) Degree of polarization is less than 0.5%; (3) Signal-to-noise ratio is about 1000; (4) Dynamic range is better than 2000:1; (5) Registration precision is better than 0.3 pixel; (6) Quantization value is 12 bit.

Spontaneous emission of an atom in the presence of nanobodies

International Nuclear Information System (INIS)

Klimov, Vasilii V; Ducloy, M; Letokhov, V S

2001-01-01

The effect of nanobodies, i.e., the bodies whose size is small compared to the emission wavelength, on spontaneous emission of an atom located near them is considered. The results of calculations performed within the framework of quantum and classical electrodynamics are presented both in analytic and graphical forms and can be readily used for planning experiments and analysis of experimental data. It is shown that nanobodies can be used to control efficiently the rate of spontaneous transitions. Thus, an excited atom located near a nanocylinder or a nanospheroid pole, whose transition dipole moment is directed normally to the nanobody surface, can decay with the rate that is tens and hundreds times higher than the decay rate in a free space. In the case of some (negative) dielectric constants, the decay rate can increase by a factor of 10 5 -10 6 and more. On the other hand, the decay of an excited atom whose transition dipole moment is directed tangentially to the nanobody surface substantially slows down. The probability of nonradiative decay of the excited state is shown to increase substantially in the presence of na-nobodies possessing losses. (review)

Normal spectral emissivity measurement of molten copper using an electromagnetic levitator superimposed with a static magnetic field

International Nuclear Information System (INIS)

Kurosawa, Ryo; Inoue, Takamitsu; Baba, Yuya; Sugioka, Ken-ichi; Kubo, Masaki; Tsukada, Takao; Fukuyama, Hiroyuki

2013-01-01

The normal spectral emissivity of molten copper was determined in the wavelength range of 780–920 nm and in the temperature range of 1288–1678 K, by directly measuring the radiance emitted by an electromagnetically levitated molten copper droplet under a static magnetic field of 1.5 T. The spectrometer for radiance measurement was calibrated using the relation between the theoretical blackbody radiance from Planck's law and the light intensity of a quasi-blackbody radiation source measured using a spectrometer at a given temperature. As a result, the normal spectral emissivity of molten copper was determined as 0.075 ± 0.011 at a wavelength of 807 nm, and it was found that its temperature dependence is negligible in the entire measurement temperature range tested. In addition, the results of the normal spectral emissivity and its wavelength dependence were discussed, in comparison with those obtained using the Drude free-electron model. (paper)

Electron and X-ray emission in collisions of multiply charged ions and atoms

International Nuclear Information System (INIS)

Woerlee, P.H.

1979-01-01

The author presents experimental results of electron and X-ray emission following slow collisions of multiply charged ions and atoms. The aim of the investigation was to study the mechanisms which are responsible for the emission. (G.T.H.)

Recombination emissions and spectral blueshift of pump radiation from ultrafast laser induced plasma in a planar water microjet

Science.gov (United States)

Anija, M.; Philip, Reji

2009-09-01

We report spectroscopic investigations of an ultrafast laser induced plasma generated in a planar water microjet. Plasma recombination emissions along with the spectral blueshift and broadening of the pump laser pulse contribute to the total emission. The laser pulses are of 100 fs duration, and the incident intensity is around 10 15 W/cm 2. The dominant mechanisms leading to plasma formation are optical tunnel ionization and collisional ionization. Spectrally resolved polarization measurements show that the high frequency region of the emission is unpolarized whereas the low frequency region is polarized. Results indicate that at lower input intensities the emission arises mainly from plasma recombinations, which is accompanied by a weak blueshift of the incident laser pulse. At higher input intensities strong recombination emissions are seen, along with a broadening and asymmetric spectral blueshift of the pump laser pulse. From the nature of the blueshifted laser pulse it is possible to deduce whether the rate of change of free electron density is a constant or variable within the pulse lifetime. Two input laser intensity regimes, in which collisional and tunnel ionizations are dominant respectively, have been thus identified.

Localization of the relative position of two atoms induced by spontaneous emission

International Nuclear Information System (INIS)

Zheng, L.; Li, C.; Li, Y.; Sun, C.P.

2005-01-01

We reexamine the back-action of emitted photons on the wave packet evolution about the relative position of two cold atoms. We show that photon recoil resulting from the spontaneous emission can induce the localization of the relative position of the two atoms through the entanglement between the spatial motion of individual atoms and their emitted photons. The obtained result provides a more realistic model for the analysis of the environment-induced localization of a macroscopic object

Improvement of LOD in Fluorescence Detection with Spectrally Nonuniform Background by Optimization of Emission Filtering.

Science.gov (United States)

Galievsky, Victor A; Stasheuski, Alexander S; Krylov, Sergey N

2017-10-17

The limit-of-detection (LOD) in analytical instruments with fluorescence detection can be improved by reducing noise of optical background. Efficiently reducing optical background noise in systems with spectrally nonuniform background requires complex optimization of an emission filter-the main element of spectral filtration. Here, we introduce a filter-optimization method, which utilizes an expression for the signal-to-noise ratio (SNR) as a function of (i) all noise components (dark, shot, and flicker), (ii) emission spectrum of the analyte, (iii) emission spectrum of the optical background, and (iv) transmittance spectrum of the emission filter. In essence, the noise components and the emission spectra are determined experimentally and substituted into the expression. This leaves a single variable-the transmittance spectrum of the filter-which is optimized numerically by maximizing SNR. Maximizing SNR provides an accurate way of filter optimization, while a previously used approach based on maximizing a signal-to-background ratio (SBR) is the approximation that can lead to much poorer LOD specifically in detection of fluorescently labeled biomolecules. The proposed filter-optimization method will be an indispensable tool for developing new and improving existing fluorescence-detection systems aiming at ultimately low LOD.

Fluorescence Intrinsic Characterization of Excitation-Emission Matrix Using Multi-Dimensional Ensemble Empirical Mode Decomposition

Directory of Open Access Journals (Sweden)

Tzu-Chien Hsiao

2013-11-01

Full Text Available Excitation-emission matrix (EEM fluorescence spectroscopy is a noninvasive method for tissue diagnosis and has become important in clinical use. However, the intrinsic characterization of EEM fluorescence remains unclear. Photobleaching and the complexity of the chemical compounds make it difficult to distinguish individual compounds due to overlapping features. Conventional studies use principal component analysis (PCA for EEM fluorescence analysis, and the relationship between the EEM features extracted by PCA and diseases has been examined. The spectral features of different tissue constituents are not fully separable or clearly defined. Recently, a non-stationary method called multi-dimensional ensemble empirical mode decomposition (MEEMD was introduced; this method can extract the intrinsic oscillations on multiple spatial scales without loss of information. The aim of this study was to propose a fluorescence spectroscopy system for EEM measurements and to describe a method for extracting the intrinsic characteristics of EEM by MEEMD. The results indicate that, although PCA provides the principal factor for the spectral features associated with chemical compounds, MEEMD can provide additional intrinsic features with more reliable mapping of the chemical compounds. MEEMD has the potential to extract intrinsic fluorescence features and improve the detection of biochemical changes.

The influence of atomic alignment on absorption and emission spectroscopy

Science.gov (United States)

Zhang, Heshou; Yan, Huirong; Richter, Philipp

2018-06-01

Spectroscopic observations play essential roles in astrophysics. They are crucial for determining physical parameters in the universe, providing information about the chemistry of various astronomical environments. The proper execution of the spectroscopic analysis requires accounting for all the physical effects that are compatible to the signal-to-noise ratio. We find in this paper the influence on spectroscopy from the atomic/ground state alignment owing to anisotropic radiation and modulated by interstellar magnetic field, has significant impact on the study of interstellar gas. In different observational scenarios, we comprehensively demonstrate how atomic alignment influences the spectral analysis and provide the expressions for correcting the effect. The variations are even more pronounced for multiplets and line ratios. We show the variation of the deduced physical parameters caused by the atomic alignment effect, including alpha-to-iron ratio ([X/Fe]) and ionisation fraction. Synthetic observations are performed to illustrate the visibility of such effect with current facilities. A study of PDRs in ρ Ophiuchi cloud is presented to demonstrate how to account for atomic alignment in practice. Our work has shown that due to its potential impact, atomic alignment has to be included in an accurate spectroscopic analysis of the interstellar gas with current observational capability.

Transition probabilities for lines of Cr II, Na II and Sb I by laser produced plasma atomic emission spectroscopy

International Nuclear Information System (INIS)

Gonzalez, A. M.; Ortiz, M.; Campos, J.

1995-01-01

Absolute transition probabilities for lines of CR II, Na II and Sb I were determined by emission spectroscopy of laser induced plasmas. the plasma was produced focusing the emission of a pulsed Nd-Yag laser on solid samples containing the atom in study. the light arising from the plasma region was collected by and spectrometer. the detector used was a time-resolved optical multichannel analyzer (OMA III EG and G). The wavelengths of the measured transitions range from 2000 sto 4100 A. The spectral resolution of the system was 0. 2 A. The method can be used in insulators materials as Cl Na crystals and in metallic samples as Al-Cr and Sn-Sn alloys. to avoid self-absorption effects the alloys were made with low Sb or Cr content. Relative transition probabilities have been determined from measurements of emission-line intensities and were placed on an absolute scale by using, where possible, accurate experimental lifetime values form the literature or theoretical data. From these measurements, values for plasma temperature (8000-24000 K), electron densities (∼∼ 10''16 cm ''-3) and self-absorption coefficients have been obtained. (Author) 56 refs

Transition probabilities for lines of Cr II, Na II and Sb I by laser produced plasma atomic emission spectroscopy

International Nuclear Information System (INIS)

Gonzalez, A.M.; Ortiz, M.; Campos, J.

1995-09-01

Absolute transition probabilities for lines of Cr II, Na II and Sb I were determined by emission spectroscopy of laser induced plasmas. The plasma was produced focusing the emission of a pulsed Nd-Yag laser on solid samples containing the atom in study. The light arising from the plasma region was collected by and spectrometer. the detector used was a time-resolved optical multichannel analyzer (OMA III EG and G). The wavelengths of the measured transitions range from 2000 to 4100 A. The spectral resolution of the system was 0.2 A. The method can be used in insulators materials as Cl Na crystals and in metallic samples as Al-Cr and Sn-Sb alloys. To avoid self-absorption effects the alloys were made with low Sb or Cr content. Relative transition probabilities have been determined from measurements of emission-line intensities and were placed on an absolute scale by using, where possible, accurate experimental lifetime values form the literature or theoretical data. From these measurements, values for plasma temperature (8000-24000K), electron densities (approx 10 ''16 cm''-3) and self-absorption coefficients have been obtained

Surface-plasmon-induced modification on the spontaneous emission spectrum via subwavelength-confined anisotropic Purcell factor.

Science.gov (United States)

Gu, Ying; Wang, Luojia; Ren, Pan; Zhang, Junxiang; Zhang, Tiancai; Martin, Olivier J F; Gong, Qihuang

2012-05-09

The mechanism of using the anisotropic Purcell factor to control the spontaneous emission linewidths in a four-level atom is theoretically demonstrated; if the polarization angle bisector of the two dipole moments lies along the axis of large/small Purcell factor, destructive/constructive interference narrows/widens the fluorescence center spectral lines. Large anisotropy of the Purcell factor, confined in the subwavelength optical mode volume, leads to rapid spectral line narrowing of atom approaching a metallic nanowire, nanoscale line width pulsing following periodically varying decay rates near a periodic metallic nanostructure, and dramatic modification on the spontaneous emission spectrum near a custom-designed resonant plasmon nanostructure. The combined system opens a good perspective for applications in ultracompact active quantum devices.

A multi-object spectral imaging instrument

International Nuclear Information System (INIS)

Gibson, G M; Dienerowitz, M; Kelleher, P A; Harvey, A R; Padgett, M J

2013-01-01

We have developed a snapshot spectral imaging system which fits onto the side camera port of a commercial inverted microscope. The system provides spectra, in real time, from multiple points randomly selected on the microscope image. Light from the selected points in the sample is directed from the side port imaging arm using a digital micromirror device to a spectrometer arm based on a dispersing prism and CCD camera. A multi-line laser source is used to calibrate the pixel positions on the CCD for wavelength. A CMOS camera on the front port of the microscope allows the full image of the sample to be displayed and can also be used for particle tracking, providing spectra of multiple particles moving in the sample. We demonstrate the system by recording the spectra of multiple fluorescent beads in aqueous solution and from multiple points along a microscope sample channel containing a mixture of red and blue dye. (paper)

Emission profiles of K-He exciplexes in cold helium gas

International Nuclear Information System (INIS)

Allard, N F

2012-01-01

Emission spectra of exciplexes composed of a light alkali atom in the first excited state and 4 He atoms have been observed in cryogenic gas in the spectral range from the atomic D lines to 6300 cm −1 . A unified semi-classical theory of line broadening has been used to determine the total profile from the center to the far wings of emission profiles of potassium perturbed by helium at low temperatures and high He density. The agreement of the theoretical peak positions of K*He n exciplexes compared to the experimental determinations is fairly good. Such comparisons provide a critical test of the calculated molecular potentials and the relevance of the theoretical approach which has been used.

Shaping the spatial and spectral emissivity at the diffraction limit

International Nuclear Information System (INIS)

Makhsiyan, Mathilde; Bouchon, Patrick; Jaeck, Julien; Pelouard, Jean-Luc; Haïdar, Riad

2015-01-01

Metasurfaces have attracted a growing interest for their ability to artificially tailor an electromagnetic response on various spectral ranges. In particular, thermal sources with unprecedented abilities, such as directionality or monochromaticity, have been achieved. However, these metasurfaces exhibit homogeneous optical properties whereas the spatial modulation of the emissivity up to the wavelength scale is at the crux of the design of original emitters. In this letter, we study an inhomogeneous metasurface made of a nonperiodic set of optical nano-antennas that spatially and spectrally control the emitted light up to the diffraction limit. Each antenna acts as an independent deep subwavelength emitter for given polarization and wavelength. Their juxtaposition at the subwavelength scale encodes far field multispectral and polarized images. This opens up promising breakthroughs for applications such as optical storage, anti-counterfeit devices, and multispectral emitters for biochemical sensing

Shaping the spatial and spectral emissivity at the diffraction limit

Energy Technology Data Exchange (ETDEWEB)

Makhsiyan, Mathilde [MiNaO, ONERA, The French Aerospace Lab, 91761 Palaiseau (France); MiNaO, Laboratoire de Photonique et de Nanostructures (LPN), CNRS, Université Paris-Saclay, route de Nozay, F-91460 Marcoussis (France); Bouchon, Patrick, E-mail: patrick.bouchon@onera.fr; Jaeck, Julien [MiNaO, ONERA, The French Aerospace Lab, 91761 Palaiseau (France); Pelouard, Jean-Luc [MiNaO, Laboratoire de Photonique et de Nanostructures (LPN), CNRS, Université Paris-Saclay, route de Nozay, F-91460 Marcoussis (France); Haïdar, Riad [MiNaO, ONERA, The French Aerospace Lab, 91761 Palaiseau (France); École Polytechnique, Département de Physique, 91128 Palaiseau (France)

2015-12-21

Metasurfaces have attracted a growing interest for their ability to artificially tailor an electromagnetic response on various spectral ranges. In particular, thermal sources with unprecedented abilities, such as directionality or monochromaticity, have been achieved. However, these metasurfaces exhibit homogeneous optical properties whereas the spatial modulation of the emissivity up to the wavelength scale is at the crux of the design of original emitters. In this letter, we study an inhomogeneous metasurface made of a nonperiodic set of optical nano-antennas that spatially and spectrally control the emitted light up to the diffraction limit. Each antenna acts as an independent deep subwavelength emitter for given polarization and wavelength. Their juxtaposition at the subwavelength scale encodes far field multispectral and polarized images. This opens up promising breakthroughs for applications such as optical storage, anti-counterfeit devices, and multispectral emitters for biochemical sensing.

Analytic cross sections for collisions of H, H2, He and Li Atoms and ions with atoms and molecules. 2

International Nuclear Information System (INIS)

Ito, Rinsuke; Tabata, Tatsuo; Shirai, Toshizo; Phaneuf, R.A.

1994-07-01

Analytic expressions fitted to Barnett's recommended data are given for the cross sections of excitation and spectral line emission by H, H + , He + , He, and He 2+ colliding with atoms and molecules. The expressions use the semiempirical functional forms proposed by Green and McNeal and some modified forms to make it possible not only to interpolate but also to extrapolate the recommended data. (author)

[Applications of atomic emission spectrum from liquid electrode discharge to metal ion detection].

Science.gov (United States)

Mao, Xiu-Ling; Wu, Jian; Ying, Yi-Bin

2010-02-01

The fast and precise detection of metal ion is an important research project concerning studies in diverse academic fields and different kinds of detecting technologies. In the present paper, the authors review the research on atomic emission spectrum based on liquid electrode discharge and its applications in the detection of metal ion. In the first part of this paper the principles and characteristics of the methods based on electrochemistry and spectroscopy were introduced. The methods of ion-selective electrode (ISE), anodic stripping voltammetry, atomic emission spectrum and atomic absorption spectrum were included in this part and discussed comparatively. Then the principles and characteristics of liquid electrode spectra for metal ion detection were introduced. The mechanism of the plasma production and the characteristics of the plasma spectrum as well as its advantages compared with other methods were discussed. Secondly, the authors divided the discharge system into two types and named them single liquid-electrode discharge and double-liquid electrode respectively, according to the number of the liquid electrode and the configuration of the discharge system, and the development as well as the present research status of each type was illustrated. Then the characteristics and configurations of the discharge systems including ECGD, SCGD, LS-APGD and capillary discharge were discussed in detail as examples of the two types. By taking advantage of the technology of atomic emission spectrum based on liquid electrode discharge, the detecting limit of heavy metals such as copper, mercury and argent as well as active metal ions including sodium, potass and magnesium can achieve microg x L(-1). Finally, the advantages and problems of the liquid-electrode discharge applied in detection of metal ion were discussed. And the applications of the atomic emission spectrum based on liquid electrode discharge were prospected.

Emission Channeling Studies of the Lattice Site of Oversized Alkali Atoms Implanted in Metals

CERN Multimedia

2002-01-01

% IS340 \\\\ \\\\ As alkali atoms have the largest atomic radius of all elements, the determination of their lattice configuration following implantation into metals forms a critical test for the various models predicting the lattice site of implanted impurity atoms. The site determination of these large atoms will especially be a crucial check for the most recent model that relates the substitutional fraction of oversized elements to their solution enthalpy. Recent exploratory $^{213}$Fr and $^{221}$Fr $\\alpha$-emission channeling experiments at ISOLDE-CERN and hyperfine interaction measurements on Fr implanted in Fe gave an indication for anomalously large substitutional fractions. To investigate further the behaviour of Fr and other alkali atoms like Cs and Rb thoroughly, more on-line emission channeling experiments are needed. We propose a number of shifts for each element, where the temperature of the implanted metals will be varied between 50$^\\circ$ and 700$^\\circ$~K. Temperature dependent measurements wi...

Effects of the fullerene (C{sub 60}) potential and position of the atom (A) on spectral characteristics of endohedral atoms A and C{sub 60}

Energy Technology Data Exchange (ETDEWEB)

Baltenkov, A S [Arifov Institute of Electronics, 100125 Tashkent (Uzbekistan); Becker, U [Fritz-Haber-Institute der Max-Planck-Gesellschaft, D-14195 Berlin (Germany); Manson, S T [Department of Physics and Astronomy, Georgia State University, Atlanta, GA 30303 (United States); Msezane, A Z, E-mail: arkbalt@mail.r, E-mail: becker@fhi-berlin.mpg.d, E-mail: manson@phy-astr.gsu.ed, E-mail: amsezane@cau.ed [Center for Theoretical Studies of Physical Systems, Clark Atlanta University, Atlanta, GA 30314 (United States)

2010-06-14

Within the framework of a model representing the potential of a C{sub 60} cage as a spherical electro-neutral layer U(r) formed by smeared carbon atoms, the effect of the details of the potential on spectral characteristics of atoms localized inside the fullerene shell has been studied. Using examples of encapsulated H and He atoms, it is shown that for potential shell thickness not exceeding 1.3-1.5 au, confinement resonance oscillations in the photoionization cross section weakly depend on the shape of the function U(r). With increasing width of the potential well, the confinement resonances in the energy dependence of the photoionization cross section disappear. In addition, it is demonstrated that displacing the doped atom from the centre of the cavity also diminishes the amplitude of the confinement resonance.

Spectral analysis of multi-dimensional self-similar Markov processes

International Nuclear Information System (INIS)

Modarresi, N; Rezakhah, S

2010-01-01

In this paper we consider a discrete scale invariant (DSI) process {X(t), t in R + } with scale l > 1. We consider a fixed number of observations in every scale, say T, and acquire our samples at discrete points α k , k in W, where α is obtained by the equality l = α T and W = {0, 1, ...}. We thus provide a discrete time scale invariant (DT-SI) process X(.) with the parameter space {α k , k in W}. We find the spectral representation of the covariance function of such a DT-SI process. By providing the harmonic-like representation of multi-dimensional self-similar processes, spectral density functions of them are presented. We assume that the process {X(t), t in R + } is also Markov in the wide sense and provide a discrete time scale invariant Markov (DT-SIM) process with the above scheme of sampling. We present an example of the DT-SIM process, simple Brownian motion, by the above sampling scheme and verify our results. Finally, we find the spectral density matrix of such a DT-SIM process and show that its associated T-dimensional self-similar Markov process is fully specified by {R H j (1), R j H (0), j = 0, 1, ..., T - 1}, where R H j (τ) is the covariance function of jth and (j + τ)th observations of the process.

Superradiators created atom by atom

Science.gov (United States)

Meschede, Dieter

2018-02-01

High radiation rates are usually associated with macroscopic lasers. Laser radiation is “coherent”—its amplitude and phase are well-defined—but its generation requires energy inputs to overcome loss. Excited atoms spontaneously emit in a random and incoherent fashion, and for N such atoms, the emission rate simply increases as N. However, if these atoms are in close proximity and coherently coupled by a radiation field, this microscopic ensemble acts as a single emitter whose emission rate increases as N2 and becomes “superradiant,” to use Dicke's terminology (1). On page 662 of this issue, Kim et al. (2) show the buildup of coherent light fields through collective emission from atomic radiators injected one by one into a resonator field. There is only one atom ever in the cavity, but the emission is still collective and superradiant. These results suggest another route toward thresholdless lasing.

Atomic data for fusion

Energy Technology Data Exchange (ETDEWEB)

Hunter, H.T.; Kirkpatrick, M.I.; Alvarez, I.; Cisneros, C.; Phaneuf, R.A. (eds.); Barnett, C.F.

1990-07-01

This report provides a handbook of recommended cross-section and rate-coefficient data for inelastic collisions between hydrogen, helium and lithium atoms, molecules and ions, and encompasses more than 400 different reactions of primary interest in fusion research. Published experimental and theoretical data have been collected and evaluated, and the recommended data are presented in tabular, graphical and parametrized form. Processes include excitation and spectral line emission, charge exchange, ionization, stripping, dissociation and particle interchange reactions. The range of collision energies is appropriate to applications in fusion-energy research.

Atomic data for fusion

International Nuclear Information System (INIS)

Hunter, H.T.; Kirkpatrick, M.I.; Alvarez, I.; Cisneros, C.; Phaneuf, R.A.; Barnett, C.F.

1990-07-01

This report provides a handbook of recommended cross-section and rate-coefficient data for inelastic collisions between hydrogen, helium and lithium atoms, molecules and ions, and encompasses more than 400 different reactions of primary interest in fusion research. Published experimental and theoretical data have been collected and evaluated, and the recommended data are presented in tabular, graphical and parametrized form. Processes include excitation and spectral line emission, charge exchange, ionization, stripping, dissociation and particle interchange reactions. The range of collision energies is appropriate to applications in fusion-energy research

Combination of the ionic-to-atomic line intensity ratios from two test elements for the diagnostic of plasma temperature and electron number density in Inductively Coupled Plasma Atomic Emission Spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Tognoni, E. [Istituto per i Processi Chimico-Fisici, Area della Ricerca del Consiglio Nazionale delle Ricerche Via Moruzzi 1, 56124 Pisa (Italy)], E-mail: tognoni@ipcf.cnr.it; Hidalgo, M.; Canals, A. [Departamento de Quimica Analitica, Nutricion y Bromatologia. Universidad de Alicante. Apdo. 99, 03080, Alicante (Spain); Cristoforetti, G.; Legnaioli, S.; Salvetti, A.; Palleschi, V. [Istituto per i Processi Chimico-Fisici, Area della Ricerca del Consiglio Nazionale delle Ricerche Via Moruzzi 1, 56124 Pisa (Italy)

2007-05-15

In Inductively Coupled Plasma-Atomic Emission Spectroscopy (ICP-AES) spectrochemical analysis, the MgII(280.270 nm)/MgI(285.213 nm) ionic to atomic line intensity ratio is commonly used as a monitor of the robustness of operating conditions. This approach is based on the univocal relationship existing between intensity ratio and plasma temperature, for a pure argon atmospheric ICP in thermodynamic equilibrium. In a multi-elemental plasma in the lower temperature range, the measurement of the intensity ratio may not be sufficient to characterize temperature and electron density. In such a range, the correct relationship between intensity ratio and plasma temperature can be calculated only when the complete plasma composition is known. We propose the combination of the line intensity ratios of two test elements (double ratio) as an effective diagnostic tool for a multi-elemental low temperature LTE plasma of unknown composition. In particular, the variation of the double ratio allows us discriminating changes in the plasma temperature from changes in the electron density. Thus, the effects on plasma excitation and ionization possibly caused by introduction of different samples and matrices in non-robust conditions can be more accurately interpreted. The method is illustrated by the measurement of plasma temperature and electron density in a specific analytic case.

Multi-sectorial convergence in greenhouse gas emissions.

Science.gov (United States)

Oliveira, Guilherme de; Bourscheidt, Deise Maria

2017-07-01

This paper uses the World Input-Output Database (WIOD) to test the hypothesis of per capita convergence in greenhouse gas (GHG) emissions for a multi-sectorial panel of countries. The empirical strategy applies conventional estimators of random and fixed effects and Arellano and Bond's (1991) GMM to the main pollutants related to the greenhouse effect. For reasonable empirical specifications, the model revealed robust evidence of per capita convergence in CH 4 emissions in the agriculture, food, and services sectors. The evidence of convergence in CO 2 emissions was moderate in the following sectors: agriculture, food, non-durable goods manufacturing, and services. In all cases, the time for convergence was less than 15 years. Regarding emissions by energy use, the largest source of global warming, there was only moderate evidence in the extractive industry sector-all other pollutants presented little or no evidence. Copyright © 2017 Elsevier Ltd. All rights reserved.

Spatial variability of oceanic phycoerythrin spectral types derived from airborne laser-induced fluorescence emissions

Science.gov (United States)

Hoge, Frank E.; Wright, C. Wayne; Kana, Todd M.; Swift, Robert N.; Yungel, James K.

1998-07-01

We report spatial variability of oceanic phycoerythrin spectral types detected by means of a blue spectral shift in airborne laser-induced fluorescence emission. The blue shift of the phycoerythrobilin fluorescence is known from laboratory studies to be induced by phycourobilin chromophore substitution at phycoerythrobilin chromophore sites in some strains of phycoerythrin-containing marine cyanobacteria. The airborne 532-nm laser-induced phycoerythrin fluorescence of the upper oceanic volume showed distinct segregation of cyanobacterial chromophore types in a flight transect from coastal water to the Sargasso Sea in the western North Atlantic. High phycourobilin levels were restricted to the oceanic (oligotrophic) end of the flight transect, in agreement with historical ship findings. These remotely observed phycoerythrin spectral fluorescence shifts have the potential to permit rapid, wide-area studies of the spatial variability of spectrally distinct cyanobacteria, especially across interfacial regions of coastal and oceanic water masses. Airborne laser-induced phytoplankton spectral fluorescence observations also further the development of satellite algorithms for passive detection of phytoplankton pigments. Optical modifications to the NASA Airborne Oceanographic Lidar are briefly described that permitted observation of the fluorescence spectral shifts.

[A cloud detection algorithm for MODIS images combining Kmeans clustering and multi-spectral threshold method].

Science.gov (United States)

Wang, Wei; Song, Wei-Guo; Liu, Shi-Xing; Zhang, Yong-Ming; Zheng, Hong-Yang; Tian, Wei

2011-04-01

An improved method for detecting cloud combining Kmeans clustering and the multi-spectral threshold approach is described. On the basis of landmark spectrum analysis, MODIS data is categorized into two major types initially by Kmeans method. The first class includes clouds, smoke and snow, and the second class includes vegetation, water and land. Then a multi-spectral threshold detection is applied to eliminate interference such as smoke and snow for the first class. The method is tested with MODIS data at different time under different underlying surface conditions. By visual method to test the performance of the algorithm, it was found that the algorithm can effectively detect smaller area of cloud pixels and exclude the interference of underlying surface, which provides a good foundation for the next fire detection approach.

Steelmaking process control using remote ultraviolet atomic emission spectroscopy

Science.gov (United States)

Arnold, Samuel

Steelmaking in North America is a multi-billion dollar industry that has faced tremendous economic and environmental pressure over the past few decades. Fierce competition has driven steel manufacturers to improve process efficiency through the development of real-time sensors to reduce operating costs. In particular, much attention has been focused on end point detection through furnace off gas analysis. Typically, off-gas analysis is done with extractive sampling and gas analyzers such as Non-dispersive Infrared Sensors (NDIR). Passive emission spectroscopy offers a more attractive approach to end point detection as the equipment can be setup remotely. Using high resolution UV spectroscopy and applying sophisticated emission line detection software, a correlation was observed between metal emissions and the process end point during field trials. This correlation indicates a relationship between the metal emissions and the status of a steelmaking melt which can be used to improve overall process efficiency.

ℓ0 -based sparse hyperspectral unmixing using spectral information and a multi-objectives formulation

Science.gov (United States)

Xu, Xia; Shi, Zhenwei; Pan, Bin

2018-07-01

Sparse unmixing aims at recovering pure materials from hyperpspectral images and estimating their abundance fractions. Sparse unmixing is actually ℓ0 problem which is NP-h ard, and a relaxation is often used. In this paper, we attempt to deal with ℓ0 problem directly via a multi-objective based method, which is a non-convex manner. The characteristics of hyperspectral images are integrated into the proposed method, which leads to a new spectra and multi-objective based sparse unmixing method (SMoSU). In order to solve the ℓ0 norm optimization problem, the spectral library is encoded in a binary vector, and a bit-wise flipping strategy is used to generate new individuals in the evolution process. However, a multi-objective method usually produces a number of non-dominated solutions, while sparse unmixing requires a single solution. How to make the final decision for sparse unmixing is challenging. To handle this problem, we integrate the spectral characteristic of hyperspectral images into SMoSU. By considering the spectral correlation in hyperspectral data, we improve the Tchebycheff decomposition function in SMoSU via a new regularization item. This regularization item is able to enforce the individual divergence in the evolution process of SMoSU. In this way, the diversity and convergence of population is further balanced, which is beneficial to the concentration of individuals. In the experiments part, three synthetic datasets and one real-world data are used to analyse the effectiveness of SMoSU, and several state-of-art sparse unmixing algorithms are compared.

Temperature profile retrieval in axisymmetric combustion plumes using multilayer perceptron modeling and spectral feature selection in the infrared CO2 emission band.

Science.gov (United States)

García-Cuesta, Esteban; de Castro, Antonio J; Galván, Inés M; López, Fernando

2014-01-01

In this work, a methodology based on the combined use of a multilayer perceptron model fed using selected spectral information is presented to invert the radiative transfer equation (RTE) and to recover the spatial temperature profile inside an axisymmetric flame. The spectral information is provided by the measurement of the infrared CO2 emission band in the 3-5 μm spectral region. A guided spectral feature selection was carried out using a joint criterion of principal component analysis and a priori physical knowledge of the radiative problem. After applying this guided feature selection, a subset of 17 wavenumbers was selected. The proposed methodology was applied over synthetic scenarios. Also, an experimental validation was carried out by measuring the spectral emission of the exhaust hot gas plume in a microjet engine with a Fourier transform-based spectroradiometer. Temperatures retrieved using the proposed methodology were compared with classical thermocouple measurements, showing a good agreement between them. Results obtained using the proposed methodology are very promising and can encourage the use of sensor systems based on the spectral measurement of the CO2 emission band in the 3-5 μm spectral window to monitor combustion processes in a nonintrusive way.

REVIEW: Spontaneous emission of an atom in the presence of nanobodies

Science.gov (United States)

Klimov, Vasilii V.; Ducloy, M.; Letokhov, V. S.

2001-07-01

The effect of nanobodies, i.e., the bodies whose size is small compared to the emission wavelength, on spontaneous emission of an atom located near them is considered. The results of calculations performed within the framework of quantum and classical electrodynamics are presented both in analytic and graphical forms and can be readily used for planning experiments and analysis of experimental data. It is shown that nanobodies can be used to control efficiently the rate of spontaneous transitions. Thus, an excited atom located near a nanocylinder or a nanospheroid pole, whose transition dipole moment is directed normally to the nanobody surface, can decay with the rate that is tens and hundreds times higher than the decay rate in a free space. In the case of some (negative) dielectric constants, the decay rate can increase by a factor of 105—106 and more. On the other hand, the decay of an excited atom whose transition dipole moment is directed tangentially to the nanobody surface substantially slows down. The probability of nonradiative decay of the excited state is shown to increase substantially in the presence of na-nobodies possessing losses.

Understanding strong-field coherent control: Measuring single-atom versus collective dynamics

International Nuclear Information System (INIS)

Trallero-Herrero, Carlos; Weinacht, Thomas; Spanner, Michael

2006-01-01

We compare the results of two strong field coherent control experiments: one which optimizes multi-photon population transfer in atomic sodium (from the 3s to the 4s state, measured by spontaneous emission from the 3p-3s transition) with one that optimizes stimulated emission on the 3p-3s transition in an ensemble of sodium atoms. Both experiments make use of intense, shaped ultrafast laser pulses discovered by a Genetic Algorithm inside a learning control loop. Optimization leads to improvements in the spontaneous and stimulated emission yields of about 4 and 10 4 , respectively, over an unshaped pulse. We interpret these results by modeling both the single atom dynamics as well as the stimulated emission buildup through numerical integration of Schroedinger's and Maxwell's equations. Our interpretation leads to the conclusion that modest yields for controlling single quantum systems can lead to dramatic effects whenever an ensemble of such systems acts collectively following controlled impulsive excitation

Dye lasers in atomic spectroscopy

International Nuclear Information System (INIS)

Lange, W.; Luther, J.; Steudel, A.

1974-01-01

The properties of dye lasers which are relevant to atomic spectroscopy are discussed. Several experiments made possible by tunable dye lasers are discussed. Applications of high spectral density dye lasers are covered in areas such as absorption spectroscopy, fluorescence spectroscopy, photoionization and photodetachment, and two- and multi-photon processes. Applications which take advantage of the narrow bandwidth of tunable dye lasers are discussed, including saturation spectroscopy, fluorescence line narrowing, classic absorption and fluorescence spectroscopy, nonoptical detection of optical resonances, heterodyne spectroscopy, and nonlinear coherent resonant phenomena. (26 figures, 180 references) (U.S.)

Coherent control of atto-second emission from aligned molecules

Energy Technology Data Exchange (ETDEWEB)

Boutu, W; Haessler, S; Merdji, H; Breger, P; Monchicourt, P; Carre, B; Salieres, P [CEA Saclay, DSM, Serv Photons Atomes Mol, F-91191 Gif Sur Yvette, (France); Waters, G [Univ Reading, JJ Thomson Phys Lab, Reading RG6 6AF, Berks, (United Kingdom); Stankiewicz, M [Jagiellonian Univ, Inst Phys, PL-30059 Krakow, (Poland); Frasinski, L J [Univ London Imperial Coll Sci Technol and Med, Blackett Lab, London SW7 2BW, (United Kingdom); Taieb, R; Caillat, J; Maquet, A [Univ Paris 06, UMR 7614, Lab Chim Phys Matiere Rayonnement, F-75231 Paris 05, (France); Taieb, R; Caillat, J; Maquet, A [LCPMR, UMR 7614, CNRS, F-75005 Paris, (France)

2008-07-01

Controlling atto-second electron wave packets and soft X-ray pulses represents a formidable challenge of general implication to many areas of science. A strong laser field interacting with atoms or molecules drives ultrafast intra-atomic/molecular electron wave packets on a sub femtosecond timescale, resulting in the emission of atto-second bursts of extreme-ultraviolet light. Controlling the intra-atomic/molecular electron dynamics enables steering of the atto-second emission. Here, we carry out a coherent control in linear molecules, where the interaction of the laser-driven electron wave packet with the core leads to quantum interferences. We demonstrate that these interferences can be finely controlled by turning the molecular axis relative to the laser polarization, that is, changing the electron re-collision angle. The wave-packet coulombic distortion modifies the spectral phase jump measured in the extreme-ultraviolet emission. Our atto-second control of the interference results in atto-second pulse shaping, useful for future applications in ultrafast coherent control of atomic and molecular processes. (authors)

Probing temporal aspects of high-order harmonic pulses via multi-colour, multi-photon ionization processes

Energy Technology Data Exchange (ETDEWEB)

Mauritsson, J [Department of Physics and Astronomy, Louisiana State University, Baton Rouge, LA 70803-4001 (United States); Johnsson, P [Department of Physics, Lund Institute of Technology, PO Box 118, SE-22100 Lund (Sweden); Lopez-Martens, R [Department of Physics, Lund Institute of Technology, PO Box 118, SE-22100 Lund (Sweden); Varju, K [Department of Physics, Lund Institute of Technology, PO Box 118, SE-22100 Lund (Sweden); L' Huillier, A [Department of Physics, Lund Institute of Technology, PO Box 118, SE-22100 Lund (Sweden); Gaarde, M B [Department of Physics and Astronomy, Louisiana State University, Baton Rouge, LA 70803-4001 (United States); Schafer, K J [Department of Physics and Astronomy, Louisiana State University, Baton Rouge, LA 70803-4001 (United States)

2005-07-14

High-order harmonics generated through the interaction of atoms and strong laser fields are a versatile, laboratory-scale source of extreme ultraviolet (XUV) radiation on a femtosecond or even attosecond time-scale. In order to be a useful experimental tool, however, this radiation has to be well characterized, both temporally and spectrally. In this paper we discuss how multi-photon, multi-colour ionization processes can be used to completely characterize either individual harmonics or attosecond pulse trains. In particular, we discuss the influence of the intensity and duration of the probe laser, and how these parameters effect the accuracy of the XUV characterization.

Probing temporal aspects of high-order harmonic pulses via multi-colour, multi-photon ionization processes

International Nuclear Information System (INIS)

Mauritsson, J; Johnsson, P; Lopez-Martens, R; Varju, K; L'Huillier, A; Gaarde, M B; Schafer, K J

2005-01-01

High-order harmonics generated through the interaction of atoms and strong laser fields are a versatile, laboratory-scale source of extreme ultraviolet (XUV) radiation on a femtosecond or even attosecond time-scale. In order to be a useful experimental tool, however, this radiation has to be well characterized, both temporally and spectrally. In this paper we discuss how multi-photon, multi-colour ionization processes can be used to completely characterize either individual harmonics or attosecond pulse trains. In particular, we discuss the influence of the intensity and duration of the probe laser, and how these parameters effect the accuracy of the XUV characterization

Multi-Gas Sensor

Science.gov (United States)

Sachse, Glenn W. (Inventor); Wang, Liang-Guo (Inventor); LeBel, Peter J. (Inventor); Steele, Tommy C. (Inventor); Rana, Mauro (Inventor)

1999-01-01

A multi-gas sensor is provided which modulates a polarized light beam over a broadband of wavelengths between two alternating orthogonal polarization components. The two orthogonal polarization components of the polarization modulated beam are directed along two distinct optical paths. At least one optical path contains one or more spectral discrimination element, with each spectral discrimination element having spectral absorption features of one or more gases of interest being measured. The two optical paths then intersect, and one orthogonal component of the intersected components is transmitted and the other orthogonal component is reflected. The combined polarization modulated beam is partitioned into one or more smaller spectral regions of interest where one or more gases of interest has an absorption band. The difference in intensity between the two orthogonal polarization components is then determined in each partitioned spectral region of interest as an indication of the spectral emission/absorption of the light beam by the gases of interest in the measurement path. The spectral emission/absorption is indicative of the concentration of the one or more gases of interest in the measurement path. More specifically, one embodiment of the present invention is a gas filter correlation radiometer which comprises a polarizer, a polarization modulator, a polarization beam splitter, a beam combiner, wavelength partitioning element, and detection element. The gases of interest are measured simultaneously and, further, can be measured independently or non-independently. Furthermore, optical or electronic element are provided to balance optical intensities between the two optical paths.

Models of Emission-Line Profiles and Spectral Energy Distributions to Characterize the Multi-Frequency Properties of Active Galactic Nuclei

Directory of Open Access Journals (Sweden)

Giovanni La Mura

2017-11-01

Full Text Available The spectra of active galactic nuclei (AGNs are often characterized by a wealth of emission lines with different profiles and intensity ratios that lead to a complicated classification. Their electromagnetic radiation spans more than 10 orders of magnitude in frequency. In spite of the differences between various classes, the origin of their activity is attributed to a combination of emitting components, surrounding an accreting supermassive black hole (SMBH, in the unified model. Currently, the execution of sky surveys, with instruments operating at various frequencies, provides the possibility to detect and to investigate the properties of AGNs on very large statistical samples. As a result of the spectroscopic surveys that allow the investigation of many objects, we have the opportunity to place new constraints on the nature and evolution of AGNs. In this contribution, we present the results obtained by working on multi-frequency data, and we discuss their relations with the available optical spectra. We compare our findings with the AGN unified model predictions, and we present a revised technique to select AGNs of different types from other line-emitting objects. We discuss the multi-frequency properties in terms of the innermost structures of the sources.

Emissive properties of xenon ions from a laser-produced plasma in the 100-140 Aa spectral range: Atomic-physics analysis of the experimental data

International Nuclear Information System (INIS)

Gilleron, F.; Poirier, M.; Blenski, T.; Schmidt, M.; Ceccotti, T.

2003-01-01

In order to design extreme ultraviolet (EUV) sources for nanolithography, xenon EUV emission has been experimentally studied in a plasma generated by the interaction of a high-power laser with a droplet jet. A theoretical model assuming that the resulting plasma is optically thick allows one to find the distribution of the relevant ions and transitions involved in the emission process. Atomic physics computations are performed using the HULLAC code to give a detailed account of the transitions involved. The importance of 4p-4d, 4d-4f, and 4d-5p transitions is stressed, as well as the need for configuration-interaction treatment of the Δn=0 transitions. Comparisons of a modeled local thermodynamical equilibrium spectrum with experiment provides qualitative agreement and permits an estimate of the plasma temperature, density, and dimensions

Atomic emission and atomic fluorescence spectroscopy in the direct current plasma

International Nuclear Information System (INIS)

Hendrick, M.S.

1985-01-01

The Direct Current Plasma (DCP) was investigated as a source for Atomic Emission (AE) and Atomic Fluorescence Spectrometry (AFS). The DCP was optimized for AE analyses using simplex optimization and Box-Behnken partial factorial experimental design, varying argon flows, and plasma position. Results were compared with a univariate search carried out in the region of the simplex optimum. Canonical analysis demonstrated that no true optimum exists for sensitivity, precision, or drift. A stationary ridge, where combinations of conditions gave comparable instrumental responses, was found. The DCP as an excitation source for AFS in a flame was used for diagnostic studies of the DCP. Moving the aerosol introduction tube behind the DCP with respect to the flame improved the characteristics of the DCP as a narrow line source, although self-absorption was observed at high concentrations of metal salt solutions in the DCP. Detection limits for Cd, Co, Cr, Cu, Fe, Mg, Mn, Zn, and Ni were in the low ng/mL region. Theoretical expressions for scatter correction with a two-line technique were derived, although no correction was necessary to achieve accurate results for standard reference materials

A multi-domain spectral method for time-fractional differential equations

Science.gov (United States)

Chen, Feng; Xu, Qinwu; Hesthaven, Jan S.

2015-07-01

This paper proposes an approach for high-order time integration within a multi-domain setting for time-fractional differential equations. Since the kernel is singular or nearly singular, two main difficulties arise after the domain decomposition: how to properly account for the history/memory part and how to perform the integration accurately. To address these issues, we propose a novel hybrid approach for the numerical integration based on the combination of three-term-recurrence relations of Jacobi polynomials and high-order Gauss quadrature. The different approximations used in the hybrid approach are justified theoretically and through numerical examples. Based on this, we propose a new multi-domain spectral method for high-order accurate time integrations and study its stability properties by identifying the method as a generalized linear method. Numerical experiments confirm hp-convergence for both time-fractional differential equations and time-fractional partial differential equations.

Atomic carbon emission from photodissociation of CO2. [planetary atmospheric chemistry

Science.gov (United States)

Wu, C. Y. R.; Phillips, E.; Lee, L. C.; Judge, D. L.

1978-01-01

Atomic carbon fluorescence, C I 1561, 1657, and 1931 A, has been observed from photodissociation of CO2, and the production cross sections have been measured. A line emission source provided the primary photons at wavelengths from threshold to 420 A. The present results suggest that the excited carbon atoms are produced by total dissociation of CO2 into three atoms. The cross sections for producing the O I 1304-A fluorescence through photodissociation of CO2 are found to be less than 0.01 Mb in the wavelength region from 420 to 835 A. The present data have implications with respect to photochemical processes in the atmospheres of Mars and Venus.

Spectrally narrowed emissions in 2,5-bis(4-biphenylyl)thiophene crystals pumped by fs laser pulse

International Nuclear Information System (INIS)

Kobayashi, S.; Sasaki, F.; Yanagi, H.; Hotta, S.; Ichikawa, M.; Taniguchi, Y.

2005-01-01

Spectrally narrowed emission (SNE) in 2,5-bis(4-biphenylyl)thiophene (BP1T) crystals is investigated using fs laser pulse. Two different types of narrowing are observed at different vibronic emission bands with increasing pump intensities. Based on their pump intensity dependence and illumination area dependence, we assign the SNE at 20,200 cm -1 (β-band) to amplified spontaneous emission (ASE) and the SNE at 21,600 cm -1 (α-band) to superfluorescence rather than ASE

Techniques for obtaining velocity distributions of atoms or ions from Doppler-broadened spectral line profiles

International Nuclear Information System (INIS)

Moran, T.G.

1986-12-01

Analysis of the doppler-broadened profiles of spectral lines radiated by atoms or ions in plasmas yields information about their velocity distributions. Researchers have analysed profiles of lines radiated by atoms in isotropic velocity distributions in several ways, one being the inversion of the integral equation which relates the velocity distribution to the line profile. This inversion formula was derived for a separate application and was given to within an arbitrary multiplicative constant. This paper presents a new derivation which obtains the inversion exactly, using a method which is easily generalized for determination of anisotropic velocity distribution functions. The technique to obtain an anisotropic velocity distribution function from line profiles measured at different angles is outlined

Measurement of Apparent Temperature in Post-Detonation Fireballs Using Atomic Emission Spectroscopy

Science.gov (United States)

2011-02-01

thermometric species into burners.3,12 Interestingly, Wilkin- son et al.6 have recently observed Al atomic emission lines in the spectrum of aluminum...candidate thermometric species must produce several strong emission lines in the spectrum that originate from different upper energy levels in order to...allow the populations of the associated states to be determined. Barium nitrate was chosen as a thermometric impurity for the current work since Ba

Cadmium, copper, lead, and zinc determination in precipitation: A comparison of inductively coupled plasma atomic emission spectrometry and graphite furnace atomization atomic absorption spectrometry

Science.gov (United States)

Reddy, M.M.; Benefiel, M.A.; Claassen, H.C.

1987-01-01

Selected trace element analysis for cadmium, copper, lead, and zinc in precipitation samples by inductively coupled plasma atomic emission Spectrometry (ICP) and by atomic absorption spectrometry with graphite furnace atomization (AAGF) have been evaluated. This task was conducted in conjunction with a longterm study of precipitation chemistry at high altitude sites located in remote areas of the southwestern United States. Coefficients of variation and recovery values were determined for a standard reference water sample for all metals examined for both techniques. At concentration levels less than 10 micrograms per liter AAGF analyses exhibited better precision and accuracy than ICP. Both methods appear to offer the potential for cost-effective analysis of trace metal ions in precipitation. ?? 1987 Springer-Verlag.

A cellular automata simulation study of surface roughening resulting from multi-atom etch pit generation during sputtering

Energy Technology Data Exchange (ETDEWEB)

Toh, Y S; Nobes, M J; Carter, G [Dept. of Electronic and Electrical Engineering, Univ. of Salford (United Kingdom)

1992-04-01

A two-dimensional square matrix of pseudo-atomic positions is erected and atom removal from the ''surface'' is effected randomly. Either single atoms or groups of atoms (to simulate multi-atom pit generation) are removed. The characteristics of the evolving roughened, terraced ''surface'' are evaluated as a function of the total number of atoms, or equivalent numbers of atomic layers, removed. These characteristics include the ''mean'' position of the sputtered surface, the standard deviation of terrace length about the mean and the form of the terrace length distributions. The results of the single-atom removal mode compare exactly with theoretical predictions in that, for large numbers of atoms removed the depth position of the mean of the terrace length distribution is identical to the mean sputtered depth and the standard deviation increases as the square root of this depth. For multi-atom removal modes (which cannot be predicted theoretically) the standard deviation also increases as the square root of the mean sputtered depth but with a larger proportionality constant. The implications of these observations for the evolution of surface morphology during high yield sputtering is discussed. (orig.).

Atomic hydrogen determination in medium-pressure microwave discharge hydrogen plasmas via emission actinometry

International Nuclear Information System (INIS)

Geng Zicai; Xu Yong; Yang Xuefeng; Wang Weiguo; Zhu Aimin

2005-01-01

Atomic hydrogen plays an important role in the chemical vapour deposition of functional materials, plasma etching and new approaches to the chemical synthesis of hydrogen-containing compounds. This work reports experimental determinations of atomic hydrogen in microwave discharge hydrogen plasmas formed from the TM 01 microwave mode in an ASTeX-type reactor, via optical emission spectroscopy using Ar as an actinometer. The relative intensities of the H atom Balmer lines and Ar-750.4 nm emissions as functions of input power and gas pressure have been investigated. At an input microwave power density of 13.5 W cm -3 , the approximate hydrogen dissociation fractions calculated from electron-impact excitation and quenching cross sections in the literature, decreased from ∼0.08 to ∼0.03 as the gas pressure was increased from 5 to 25 Torr. The influences of the above cross sections, and the electron and gas temperatures of the plasmas on the determination of the hydrogen dissociation fraction data have been discussed

Correlative Spectral Analysis of Gamma-Ray Bursts using Swift-BAT and GLAST-GBM

International Nuclear Information System (INIS)

Stamatikos, Michael; Sakamoto, Taka; Band, David L.

2008-01-01

We discuss the preliminary results of spectral analysis simulations involving anticipated correlated multi-wavelength observations of gamma-ray bursts (GRBs) using Swift's Burst Alert Telescope (BAT) and the Gamma-Ray Large Area Space Telescope's (GLAST) Burst Monitor (GLAST-GBM), resulting in joint spectral fits, including characteristic photon energy (E peak ) values, for a conservative annual estimate of ∼30 GRBs. The addition of BAT's spectral response will (i) complement in-orbit calibration efforts of GBM's detector response matrices, (ii) augment GLAST's low energy sensitivity by increasing the ∼20-100 keV effective area, (iii) facilitate ground-based follow-up efforts of GLAST GRBs by increasing GBM's source localization precision, and (iv) help identify a subset of non-triggered GRBs discovered via off-line GBM data analysis. Such multi-wavelength correlative analyses, which have been demonstrated by successful joint-spectral fits of Swift-BAT GRBs with other higher energy detectors such as Konus-WIND and Suzaku-WAM, would enable the study of broad-band spectral and temporal evolution of prompt GRB emission over three energy decades, thus potentially increasing science return without placing additional demands upon mission resources throughout their contemporaneous orbital tenure over the next decade.

Correlative Spectral Analysis of Gamma-Ray Bursts using Swift-BAT and GLAST-GBM

International Nuclear Information System (INIS)

Stamatikos, Michael; Sakamoto, Takanori; Band, David L.

2008-01-01

We discuss the preliminary results of spectral analysis simulations involving anticipated correlated multi-wavelength observations of gamma-ray bursts (GRBs) using Swift's Burst Alert Telescope (BAT) and the Gamma-Ray Large Area Space Telescope's (GLAST) Burst Monitor (GLAST-GBM), resulting in joint spectral fits, including characteristic photon energy (E peak ) values, for a conservative annual estimate of ∼30 GRBs. The addition of BAT/s spectral response will (i) complement in-orbit calibration efforts of GBM's detector response matrices, (ii) augment GLAST's low energy sensitivity by increasing the ∼20-100 keV effective area, (iii) facilitate ground-based follow-up efforts of GLAST GRBs by increasing GBM's source localization precision, and (iv) help identify a subset of non-triggered GRBs discovered via off-line GBM data analysis. Such multi-wavelength correlative analyses, which have been demonstrated by successful joint-spectral fits of Swift-BAT GRBs with other higher energy detectors such as Konus-WIND and Suzaku-WAM, would enable the study of broad-band spectral and temporal evolution of prompt GRB emission over three energy decades, thus potentially increasing science return without placing additional demands upon mission resources throughout their contemporaneous orbital tenure over the next decade

Spatial Dependent Spontaneous Emission of an Atom in a Semi-Infinite Waveguide of Rectangular Cross Section

Science.gov (United States)

Song, Hai-Xi; Sun, Xiao-Qi; Lu, Jing; Zhou, Lan

2018-01-01

We study a quantum electrodynamics (QED) system made of a two-level atom and a semi-infinite rectangular waveguide, which behaves as a perfect mirror in one end. The spatial dependence of the atomic spontaneous emission has been included in the coupling strength relevant to the eigenmodes of the waveguide. The role of retardation is studied for the atomic transition frequency far away from the cutoff frequencies. The atom-mirror distance introduces different phases and retardation times into the dynamics of the atom interacting resonantly with the corresponding transverse modes. It is found that the upper state population decreases from its initial as long as the atom-mirror distance does not vanish, and is lowered and lowered when more and more transverse modes are resonant with the atom. The atomic spontaneous emission can be either suppressed or enhanced by adjusting the atomic location for short retardation time. There are partial revivals and collapses due to the photon reabsorbed and re-emitted by the atom for long retardation time. Supported by National Natural Science Foundation of China under Grant Nos. 11374095, 11422540, 11434011, and 11575058, National Fundamental Research Program of China (the 973 Program) under Grant No. 2012CB922103, and Hunan Provincial Natural Science Foundation of China under Grant No. 11JJ7001

Atomic emission spectroscopy for the on-line monitoring of incineration processes

NARCIS (Netherlands)

Timmermans, E.A.H.; de Groote, F.P.J.; Jonkers, J.; Gamero, A.; Sola, A.; Mullen, van der J.J.A.M.

2003-01-01

A diagnostic measurement system based on atomic emission spectroscopy has been developed for the purpose of on-line monitoring of hazardous elements in industrial combustion gases. The aim was to construct a setup with a high durability for rough and variable experimental conditions, e.g. a strongly

First Experimental Impulse-Radio Ultra-Wideband Transmission Under the Russian Spectral Emission Mask

DEFF Research Database (Denmark)

Grakhova, Elizaveta P.; Rommel, Simon; Jurado-Navas, Antonio

2016-01-01

Ultra-wideband impulse-radio wireless transmission under the stringent conditions and complex shape of the Russian spectral emission mask is experimentally demonstrated for the first time. Transmission of 1Gbit/s and 1.25Gbit/s signals over distances of 6m and 3m is achieved with a BER below 3.8×10-3....

Spectral properties of a V-type three-level atom driven by two bichromatic fields

International Nuclear Information System (INIS)

Li Peng; Nakajima, Takashi; Ning Xijing

2006-01-01

We theoretically investigate the spectral properties of a V-type three-level atom driven by two bichromatic fields with a common frequency difference. By decomposing the master equation using harmonic expansions and invoking quantum regression theorem, fluorescence and probe absorption spectra of the strong atomic transition are numerically calculated under the steady state condition. We find that both fluorescence and absorption spectra exhibit two interesting features, which are equidistant comblike structures and phase-dependent line splittings. In the comblike structures, each fluorescence peak can be made subnatural by manipulating the relative intensities of the coupling fields, while for the absorption lines only the central peak can be narrowed. Line splittings are induced by the relative phase delay between the envelopes of the amplitudes of the two bichromatic fields. Interestingly, we find that the manipulation of the relative phase delay results in the emergence of sharp subnatural dips in the absorption spectra. As a natural consequence of the subnatural absorption dips, absorption spectra in atomic vapors exhibit striking subnatural burning holes for the counterpropagating probe beam geometry

Contrast-enhanced spectral mammography vs. mammography and MRI - clinical performance in a multi-reader evaluation

NARCIS (Netherlands)

Fallenberg, E.M.; Schmitzberger, F.F.; Amer, H.; Ingold-Heppner, B.; Balleyguier, C.; Diekmann, F.; Engelken, F.; Mann, R.M.; Renz, D.M.; Bick, U.; Hamm, B.; Dromain, C.

2017-01-01

OBJECTIVES: To compare the diagnostic performance of contrast-enhanced spectral mammography (CESM) to digital mammography (MG) and magnetic resonance imaging (MRI) in a prospective two-centre, multi-reader study. METHODS: One hundred seventy-eight women (mean age 53 years) with invasive breast

Deblurring sequential ocular images from multi-spectral imaging (MSI) via mutual information.

Science.gov (United States)

Lian, Jian; Zheng, Yuanjie; Jiao, Wanzhen; Yan, Fang; Zhao, Bojun

2018-06-01

Multi-spectral imaging (MSI) produces a sequence of spectral images to capture the inner structure of different species, which was recently introduced into ocular disease diagnosis. However, the quality of MSI images can be significantly degraded by motion blur caused by the inevitable saccades and exposure time required for maintaining a sufficiently high signal-to-noise ratio. This degradation may confuse an ophthalmologist, reduce the examination quality, or defeat various image analysis algorithms. We propose an early work specially on deblurring sequential MSI images, which is distinguished from many of the current image deblurring techniques by resolving the blur kernel simultaneously for all the images in an MSI sequence. It is accomplished by incorporating several a priori constraints including the sharpness of the latent clear image, the spatial and temporal smoothness of the blur kernel and the similarity between temporally-neighboring images in MSI sequence. Specifically, we model the similarity between MSI images with mutual information considering the different wavelengths used for capturing different images in MSI sequence. The optimization of the proposed approach is based on a multi-scale framework and stepwise optimization strategy. Experimental results from 22 MSI sequences validate that our approach outperforms several state-of-the-art techniques in natural image deblurring.

On multi-spectral quantitative photoacoustic tomography in diffusive regime

International Nuclear Information System (INIS)

Bal, Guillaume; Ren, Kui

2012-01-01

The objective of quantitative photoacoustic tomography (qPAT) is to reconstruct the diffusion, absorption and Grüneisen thermodynamic coefficients of heterogeneous media from knowledge of the interior absorbed radiation. It has been shown in Bal and Ren (2011 Inverse Problems 27 075003), based on diffusion theory, that with data acquired at one given wavelength, all three coefficients cannot be reconstructed uniquely. In this work, we study the multi-spectral qPAT problem and show that when multiple wavelength data are available, all coefficients can be reconstructed simultaneously under minor prior assumptions. Moreover, the reconstructions are shown to be very stable. We present some numerical simulations that support the theoretical results. (paper)

Optical perception for detection of cutaneous T-cell lymphoma by multi-spectral imaging

International Nuclear Information System (INIS)

Hsiao, Yu-Ping; Wang, Hsiang-Chen; Chen, Shih-Hua; Tsai, Chung-Hung; Yang, Jen-Hung

2014-01-01

In this study, the spectrum of each picture element of the patient’s skin image was obtained by multi-spectral imaging technology. Spectra of normal or pathological skin were collected from 15 patients. Principal component analysis and principal component scores of skin spectra were employed to distinguish the spectral characteristics with different diseases. Finally, skin regions with suspected cutaneous T-cell lymphoma (CTCL) lesions were successfully predicted by evaluation and classification of the spectra of pathological skin. The sensitivity and specificity of this technique were 89.65% and 95.18% after the analysis of about 109 patients. The probability of atopic dermatitis and psoriasis patients misinterpreted as CTCL were 5.56% and 4.54%, respectively. (paper)

Emission and electron transitions in an atom interacting with an ultrashort electromagnetic pulse

International Nuclear Information System (INIS)

Matveev, V.I.

2003-01-01

Electron transitions and emission of an atom interacting with a spatially inhomogeneous ultrashort electromagnetic pulse are considered. The excitation and ionization probabilities are obtained as well as the spectra and cross sections of the reemission of such a pulse by atoms. By way of an example, one- and two-electron inelastic processes accompanying the interaction of ultrashort pulses with hydrogen- and helium-like atoms are considered. The developed technique makes it possible to take into account exactly the spatial nonuniformity of the ultrashort pulse field and photon momenta in the course of reemission

Using RPAS Multi-Spectral Imagery to Characterise Vigour, Leaf Development, Yield Components and Berry Composition Variability within a Vineyard

Directory of Open Access Journals (Sweden)

Clara Rey-Caramés

2015-10-01

Full Text Available Implementation of precision viticulture techniques requires the use of emerging sensing technologies to assess the vineyard spatial variability. This work shows the capability of multispectral imagery acquired from a remotely piloted aerial system (RPAS, and the derived spectral indices to assess the vegetative, productive, and berry composition spatial variability within a vineyard (Vitis vinifera L.. Multi-spectral imagery of 17 cm spatial resolution was acquired using a RPAS. Classical vegetation spectral indices and two newly defined normalised indices, NVI1 = (R802 − R531/(R802 + R531 and NVI2 = (R802 − R570/(R802 + R570, were computed. Their spatial distribution and relationships with grapevine vegetative, yield, and berry composition parameters were studied. Most of the spectral indices and field data varied spatially within the vineyard, as showed through the variogram parameters. While the correlations were significant but moderate among the spectral indices and the field variables, the kappa index showed that the spatial pattern of the spectral indices agreed with that of the vegetative variables (0.38–0.70 and mean cluster weight (0.40. These results proved the utility of the multi-spectral imagery acquired from a RPAS to delineate homogeneous zones within the vineyard, allowing the grapegrower to carry out a specific management of each subarea.

Gas chromatography of organic microcontaminants using atomic emission and mass spectrometric detection combined in one instrument (GC-AED/MS)

NARCIS (Netherlands)

Mol, H.G.J.; Hankemeier, T.; Brinkman, U.A.T.

1999-01-01

This study describes the coupling of an atomic-emission detector and mass-spectrometric detector to a single gas chromatograph. Splitting of the column effluent enables simultaneous detection by atomic-emission detection (AED) and mass spectrometry (MS) and yields a powerful system for the target

Electric discharges in air - Near infrared emission spectrum.

Science.gov (United States)

Benesch, W. M.; Saum, K. A.

1972-01-01

The emission from glow discharges in flowing air has been investigated in the 1- to 5-micron wavelength region with a vacuum spectrometer. Most of the spectral features observed in the pressure range of .5 to 10 torr are identified, including atomic lines of OI, NI, and HI and molecular bands of N2, NO, N2O, CO2, and CO. The spectra are presented as a function of pressure and a table compiled of the atomic lines. Of particular interest are the contrasts between the emission of the air discharge and that of the pure gases, nitrogen and oxygen. In addition, the results of studies of several discharge modes, employing steady voltages and pulsed, provide data on details of the energy flow within the plasma.

Simultaneous multi-element atomic absorption system using photodiode array detector

International Nuclear Information System (INIS)

Tong, S.L.; Chin, K.S.

1994-01-01

A photodiode array (PDA) detector-multichannel analyser (MCA) system has been coupled to a flame and a graphite furnace atomiser and tested for simultaneous multielement atomic absorption analysis. Multielement hollow cathode lamps (HCL) are used as light source. Spectral lines are dispersed through a spectrograph with triple gratings and detected by a 25.4 mm PDA detector consisting of 1024 elements. The optical MCA system is capable of recording multiple spectra spanned by the spectrograph/PDA. The transmitted intensity spectra obtained for the standard and analyte solutions during flame or graphite furnace atomisation are converted to absorbance spectra using the MCA software provided. Results from the comparison studies show that the linear range and sensitivities for Ni-Co-Fe and Cu-Cr obtained from the simultaneous measurements are within the same order of magnitudes as those from conventional single element determinations using photomultiplier tube detection. The study also shows that non-atomic absorption can be readily corrected by a two-line method where non-atomic absorption lines can be chosen from the spectra recorded simultaneously. The proposed system has been evaluated for the determination of trace elements using NBS standard reference water SRM 1643b

Information Retrieval from SAGE II and MFRSR Multi-Spectral Extinction Measurements

Science.gov (United States)

Lacis, Andrew A.; Hansen, James E. (Technical Monitor)

2001-01-01

Direct beam spectral extinction measurements of solar radiation contain important information on atmospheric composition in a form that is essentially free from multiple scattering contributions that otherwise tend to complicate the data analysis and information retrieval. Such direct beam extinction measurements are available from the solar occultation satellite-based measurements made by the Stratospheric and Aerosol Gas Experiment (SAGE II) instrument and by ground-based Multi-Filter Shadowband Radiometers (MFRSRs). The SAGE II data provide cross-sectional slices of the atmosphere twice per orbit at seven wavelengths between 385 and 1020 nm with approximately 1 km vertical resolution, while the MFRSR data provide atmospheric column measurements at six wavelengths between 415 and 940 nm but at one minute time intervals. We apply the same retrieval technique of simultaneous least-squares fit to the observed spectral extinctions to retrieve aerosol optical depth, effective radius and variance, and ozone, nitrogen dioxide, and water vapor amounts from the SAGE II and MFRSR measurements. The retrieval technique utilizes a physical model approach based on laboratory measurements of ozone and nitrogen dioxide extinction, line-by-line and numerical k-distribution calculations for water vapor absorption, and Mie scattering constraints on aerosol spectral extinction properties. The SAGE II measurements have the advantage of being self-calibrating in that deep space provides an effective zero point for the relative spectral extinctions. The MFRSR measurements require periodic clear-day Langley regression calibration events to maintain accurate knowledge of instrument calibration.

Dynamical Evolution of Properties for Atom and Field in the Process of Two-Photon Absorption and Emission Between Atomic Levels

Science.gov (United States)

Wang, Jian-ming; Xu, Xue-xiang

2018-04-01

Using dressed state method, we cleverly solve the dynamics of atom-field interaction in the process of two-photon absorption and emission between atomic levels. Here we suppose that the atom is initially in the ground state and the optical field is initially in Fock state, coherent state or thermal state, respectively. The properties of the atom, including the population in excited state and ground state, the atom inversion, and the properties for optical field, including the photon number distribution, the mean photon number, the second-order correlation function and the Wigner function, are discussed in detail. We derive their analytical expressions and then make numerical analysis for them. In contrast with Jaynes-Cummings model, some similar results, such as quantum Rabi oscillation, revival and collapse, are also exhibit in our considered model. Besides, some novel nonclassical states are generated.

Production of hollow atoms by high brightness x-ray sources and its applications

International Nuclear Information System (INIS)

Moribayashi, Kengo

2004-01-01

We study x-ray emissions from the (multi-)inner-shell states and hollow atoms of Si ions excited by high intensity x-ray sources. It is found that the x-ray number from multi-inner-shell excited states (1s 2 2s 2 2p k 3s 2 3p 2 , k=1-4) and hollow atoms (1s 2 2s 2 3p 2 ) is affected greatly by the high intensity short-pulse x-rays and little by weak intensity post-long pulse x-rays. The ratio of the x-ray intensities from hollow atoms to those from the multi-inner-shell excited states becomes almost independent of the pulses and dependent on the intensities of x-ray sources. This ratio may be used for the measurement of intensities of high intensity short pulse x-ray sources. (author)

Secondary electron emission from Au by medium energy atomic and molecular ions

CERN Document Server

Itoh, A; Obata, F; Hamamoto, Y; Yogo, A

2002-01-01

Number distributions of secondary electrons emitted from a Au metal surface have been measured for atomic and molecular ions of H sup + , He sup + , C sup + , N sup + , O sup + , H sup + sub 2 , H sup + sub 3 , HeH sup + , CO sup + and O sup + sub 2 in the energy range 0.3-2.0 MeV. The emission statistics obtained are described fairly well by a Polya function. The Polya parameter b, determining the distribution shape, is found to decrease monotonously with increasing emission yield gamma, revealing a surprising relationship of b gamma approx 1 over the different projectile species and impact energies. This finding supports certainly the electron cascading model. Also we find a strong negative molecular effect for heavier molecular ions, showing a significant reduction of gamma compared to the estimated values using constituent atomic projectile data.

Using a digital multimeter to capture spectral information generated by a spectrophotometer broadcast / atomic absorption

International Nuclear Information System (INIS)

Villalobos Chaves, Alberto E.

2006-01-01

Spectral analysis capability of the information generated by a spectrophotometer broadcast / shimadzu AA 640-13 atomic absorption has increased, through the capture of data, using a digital multimeter as the interface between the spectrophotometer and a computer. To facilitate the identification of analytes was created Chromulan format files for the 99 chemical elements reported in the literature, and covering the region between 200 nm and 900 nm, the subject of this study. (author) [es

Theoretical profiles of the spectral lines of the hydrogen atom; Profils theoriques des raies spectrales de l'atome d'hydrogene

Energy Technology Data Exchange (ETDEWEB)

Nguyen, H; Herman, L [Universite de la Sorbonne, Lab. de Recherche Physique, 75 - Paris (France); Drawin, H W [Commissariat a l' Energie Atomique, Fontenay-aux-Roses, Association Euratom-CEA, Groupe de Recherches sur la Fusion Controlee (France). Centre d' Etudes Nucleaires

1965-07-01

The line-broadening problem of the hydrogen lines has been formulated in the quasistatic approximation as far as the ions are concerned, and in the classical path approximation as far as the broadening due to collisions with electrons is concerned. These electrons interfere in different numerical results only by the self-correlation function of the fluctuating electrical field strength created at each point in the plasma. The Lewis correction has been applied, but using the whole velocity distribution function of the electrons. The formula which represents the usual impact profile, valid only for frequencies much smaller than the plasma frequency, has been extended using another formula which will be valid up to the neighbourhood of that spectral region where the quasi-static approximation begins to be valid also for the electrons. As an example, the line profile of Ly {alpha} is given by some graphs for T = 10{sup 4} deg. K and electron densities N = 10{sup 17} cm{sup -3} and N = 10{sup 18}cm{sup -3}. (authors) [French] Le probleme d'elargissement des raies de l'atome H est formule dans l'approximation quasi-statique en ce qui concerne les ions et dans l'approximation du chemin classique en ce qui concerne les electrons. Ceux-ci interviennent dans differents resultats uniquement par la fonction auto-correlation du champ electrique fluctuant qu'ils creent en chaque point du plasma. La correction de Lewis a ete appliquee mais en tenant compte de la distribution des vitesses electroniques. La formule donnant les profils d'impact habituels, valable seulement pour des frequences tres inferieures a la frequence du plasma, est ainsi prolongee de maniere continue par une autre formule, valable jusqu'au voisinage de la region spectrale ou l'approximation quasistatique commence a etre egalement justifiee pour les electrons. A titre d'illustration on represente graphiquement le profil de la raie Ly {alpha} pour T = 10{sup 4} deg. K et des densites electroniques de N = 10{sup

One color multi-photon ionization of the Gadolinium atom in near UV region

International Nuclear Information System (INIS)

Kim, Jin Tae; Yi, Jong Hoon; Lhee, Yong Joo; Lee, Jong Min

1999-01-01

We have investigated the states of the gadolinium atom in near ultra-violet (UV) region (∼410 nm) using single photon excitation using resonance ionization mass spectrometry (RIMS). Around 70 transitions among observed 180 single color multi-photon ionization signals have been assigned. Most of the multi-photon processes of the assigned ion signals are through single photon resonant three photon ionization and through two photon resonant three photon ionization. (author)

Multi-point laser ignition device

Energy Technology Data Exchange (ETDEWEB)

McIntyre, Dustin L.; Woodruff, Steven D.

2017-01-17

A multi-point laser device comprising a plurality of optical pumping sources. Each optical pumping source is configured to create pumping excitation energy along a corresponding optical path directed through a high-reflectivity mirror and into substantially different locations within the laser media thereby producing atomic optical emissions at substantially different locations within the laser media and directed along a corresponding optical path of the optical pumping source. An output coupler and one or more output lenses are configured to produce a plurality of lasing events at substantially different times, locations or a combination thereof from the multiple atomic optical emissions produced at substantially different locations within the laser media. The laser media is a single continuous media, preferably grown on a single substrate.

Spectral effects on some physical coefficients of x-Ray interaction with materials of low atomic number

International Nuclear Information System (INIS)

EL-Kazzaz, S.A.; Youssef, M.; EL-Hadad, S.; and EL-Nadi, L.M.

1988-01-01

X-ray spectra were measured before and after passing through some materials of medical importance applying X-ray diffraction. The mass absorption coefficients of these materials were determined at X-ray peak voltages 27, 30 and 42 kV-p making use the measured spectrum and also by using the direct beam absorption. It has been found that the mass absorption coefficients calculated from the X-ray spectral distribution analysis are in general lower than those obtained considering the direct beam method. From the study of the atomic number and energy dependence of the mass absorption coefficients it has been found that the dependence of the coefficients calculated from the spectral distribution is good agreement with the previously studied data for monoenergetic x-ray beam. Also the roentgen - to - Rad conversion factors were determined at the different used energies and materials. The value of the mass absorption coefficients calculated from the spectral distribution is recommended for use in dose calculation

Spectral fitting method for the solution of time-dependent Schroedinger equations: Applications to atoms in intense laser fields

International Nuclear Information System (INIS)

Qiao Haoxue; Cai Qingyu; Rao Jianguo; Li Baiwen

2002-01-01

A spectral fitting method for solving the time-dependent Schroedinger equation has been developed and applied to the atom in intense laser fields. This method allows us to obtain a highly accurate time-dependent wave function with a contribution from the high-order term of Δt. Moreover, the time-dependent wave function is determined on a small number of discrete mesh points, thus making calculations simple and accurate. This method is illustrated by computing wave functions and harmonic generation spectra of a model atom in laser fields

Three-Dimensional Reconstruction from Single Image Base on Combination of CNN and Multi-Spectral Photometric Stereo

Science.gov (United States)

Lu, Liang; Qi, Lin; Luo, Yisong; Jiao, Hengchao; Dong, Junyu

2018-01-01

Multi-spectral photometric stereo can recover pixel-wise surface normal from a single RGB image. The difficulty lies in that the intensity in each channel is the tangle of illumination, albedo and camera response; thus, an initial estimate of the normal is required in optimization-based solutions. In this paper, we propose to make a rough depth estimation using the deep convolutional neural network (CNN) instead of using depth sensors or binocular stereo devices. Since high-resolution ground-truth data is expensive to obtain, we designed a network and trained it with rendered images of synthetic 3D objects. We use the model to predict initial normal of real-world objects and iteratively optimize the fine-scale geometry in the multi-spectral photometric stereo framework. The experimental results illustrate the improvement of the proposed method compared with existing methods. PMID:29498703

Three-Dimensional Reconstruction from Single Image Base on Combination of CNN and Multi-Spectral Photometric Stereo

Directory of Open Access Journals (Sweden)

Liang Lu

2018-03-01

Full Text Available Multi-spectral photometric stereo can recover pixel-wise surface normal from a single RGB image. The difficulty lies in that the intensity in each channel is the tangle of illumination, albedo and camera response; thus, an initial estimate of the normal is required in optimization-based solutions. In this paper, we propose to make a rough depth estimation using the deep convolutional neural network (CNN instead of using depth sensors or binocular stereo devices. Since high-resolution ground-truth data is expensive to obtain, we designed a network and trained it with rendered images of synthetic 3D objects. We use the model to predict initial normal of real-world objects and iteratively optimize the fine-scale geometry in the multi-spectral photometric stereo framework. The experimental results illustrate the improvement of the proposed method compared with existing methods.

Extending the relationship between global warming and cumulative carbon emissions to multi-millennial timescales

International Nuclear Information System (INIS)

Frölicher, Thomas L; Paynter, David J

2015-01-01

The transient climate response to cumulative carbon emissions (TCRE) is a highly policy-relevant quantity in climate science. The TCRE suggests that peak warming is linearly proportional to cumulative carbon emissions and nearly independent of the emissions scenario. Here, we use simulations of the Earth System Model (ESM) from the Geophysical Fluid Dynamics Laboratory (GFDL) to show that global mean surface temperature may increase by 0.5 °C after carbon emissions are stopped at 2 °C global warming, implying an increase in the coefficient relating global warming to cumulative carbon emissions on multi-centennial timescales. The simulations also suggest a 20% lower quota on cumulative carbon emissions allowed to achieve a policy-driven limit on global warming. ESM estimates from the Coupled Model Intercomparison Project Phase 5 (CMIP5–ESMs) qualitatively agree on this result, whereas Earth System Models of Intermediate Complexity (EMICs) simulations, used in the IPCC 5th assessment report to assess the robustness of TCRE on multi-centennial timescales, suggest a post-emissions decrease in temperature. The reason for this discrepancy lies in the smaller simulated realized warming fraction in CMIP5–ESMs, including GFDL ESM2M, than in EMICs when carbon emissions increase. The temperature response to cumulative carbon emissions can be characterized by three different phases and the linear TCRE framework is only valid during the first phase when carbon emissions increase. For longer timescales, when emissions tape off, two new metrics are introduced that better characterize the time-dependent temperature response to cumulative carbon emissions: the equilibrium climate response to cumulative carbon emissions and the multi-millennial climate response to cumulative carbon emissions. (letter)

Ultrafast spectral interferometry of resonant secondary emission from quantum wells: From Rayleigh scattering to coherent emission from biexcitons

DEFF Research Database (Denmark)

Birkedal, Dan; Shah, Jagdeep; Pfeiffer, L. N.

1999-01-01

Recent investigations of secondary emission from quantum well excitons following ultrafast resonant excitation have demonstrated an intricate interplay of coherent Rayleigh scattering and incoherent luminescence. We have very recently demonstrated that it is possible to isolate and time resolve...... the coherent field associated with Rayleigh component using ultrafast spectral interferometry or Tadpole, thus, obtaining substantial and new information of the nature of resonant secondary emission. Our observation demonstrates that Rayleigh scattering from static disorder is inherently a non-ergodic process...... invalidating the use of current theories using ensemble averages to describe our observations. Furthermore, we report here a new and hitherto unknown coherent scattering mechanism involving the two-photon coherence associated with the biexciton transition. The process leaves an exciton behind taking up...

Analytical characteristics of a continuum-source tungsten coil atomic absorption spectrometer.

Science.gov (United States)

Rust, Jennifer A; Nóbrega, Joaquim A; Calloway, Clifton P; Jones, Bradley T

2005-08-01

A continuum-source tungsten coil electrothermal atomic absorption spectrometer has been assembled, evaluated, and employed in four different applications. The instrument consists of a xenon arc lamp light source, a tungsten coil atomizer, a Czerny-Turner high resolution monochromator, and a linear photodiode array detector. This instrument provides simultaneous multi-element analyses across a 4 nm spectral window with a resolution of 0.024 nm. Such a device might be useful in many different types of analyses. To demonstrate this broad appeal, four very different applications have been evaluated. First of all, the temperature of the gas phase was measured during the atomization cycle of the tungsten coil, using tin as a thermometric element. Secondly, a summation approach for two absorption lines for aluminum falling within the same spectral window (305.5-309.5 nm) was evaluated. This approach improves the sensitivity without requiring any additional preconcentration steps. The third application describes a background subtraction technique, as it is applied to the analysis of an oil emulsion sample. Finally, interference effects caused by Na on the atomization of Pb were studied. The simultaneous measurements of Pb and Na suggests that negative interference arises at least partially from competition between Pb and Na atoms for H2 in the gas phase.

Ab-initio modeling of an iron laser-induced plasma: Comparison between theoretical and experimental atomic emission spectra

International Nuclear Information System (INIS)

Colgan, J.; Judge, E.J.; Kilcrease, D.P.; Barefield, J.E.

2014-01-01

We report on efforts to model the Fe emission spectrum generated from laser-induced breakdown spectroscopy (LIBS) measurements on samples of pure iron oxide (Fe 2 O 3 ). Our modeling efforts consist of several components. We begin with ab-initio atomic structure calculations performed by solving the Hartree–Fock equations for the neutral and singly ionized stages of Fe. Our energy levels are then adjusted to their experimentally known values. The atomic transition probabilities and atomic collision quantities are also computed in an ab-initio manner. We perform LTE or non-LTE calculations that generate level populations and, subsequently, an emission spectrum for the iron plasma for a range of electron temperatures and electron densities. Such calculations are then compared to the experimental spectrum. We regard our work as a preliminary modeling effort that ultimately strives towards the modeling of emission spectra from even more complex samples where less atomic data are available. - Highlights: • LIBS plasma of iron oxide • Ab-initio theoretical Modeling • Discussion of LTE versus non-LTE criteria and assessment • Boltzmann plots for Fe—determination of when LTE is a valid assumption • Emission spectra for Fe—comparison of theoretical modeling and measurement: good agreement obtained

Atomic Absorption, Atomic Fluorescence, and Flame Emission Spectrometry.

Science.gov (United States)

Horlick, Gary

1984-01-01

This review is presented in six sections. Sections focus on literature related to: (1) developments in instrumentation, measurement techniques, and procedures; (2) performance studies of flames and electrothermal atomizers; (3) applications of atomic absorption spectrometry; (4) analytical comparisons; (5) atomic fluorescence spectrometry; and (6)…

Halogenated salicylaldehyde azines: The heavy atom effect on aggregation-induced emission enhancement properties

International Nuclear Information System (INIS)

Chen, Xiao-tong; Tong, Ai-jun

2014-01-01

This study investigates the heavy-atom effect (HAE) on aggregation-induced emission enhancement (AIEE) properties of salicylaldehyde azines. For this purpose, a series of halogenated salicylaldehyde azine derivatives, namely, chloro-salicylaldehyde azine (1), bromo-salicylaldehyde azine (2) and iodo-salicylaldehyde azine (3) are synthesized. 1 and 2 display typical AIEE characteristics of salicylaldehyde azine compounds; whereas for the iodo-substituent in 3, is found to be effective “external” heavy atom quenchers to salicylaldehyde azine fluorescence in aggregated state. Based on its weak fluorescence in aggregated state and relative strong fluorescence in dispersed state, 3 can also be applied as a turn-on fluorescence probe for egg albumin detection attributed to hydrophobic interaction. -- Highlights: • This study investigates the heavy-atom effect (HAE) on aggregation-induced emission enhancement (AIEE) properties of salicylaldehyde azines. • Chloro- and bromo-salicylaldehyde display typical AIEE properties of salicylaldehyde azine, whereas the iodo-substitute quenches AIEE in aggregated state. • Iodo-salicylaldehyde can be applied as a turn-on fluorescence probe for egg albumin detection attributed to hydrophobic interaction

Electronic structure of atoms: atomic spectroscopy information system

International Nuclear Information System (INIS)

Kazakov, V V; Kazakov, V G; Kovalev, V S; Meshkov, O I; Yatsenko, A S

2017-01-01

The article presents a Russian atomic spectroscopy, information system electronic structure of atoms (IS ESA) (http://grotrian.nsu.ru), and describes its main features and options to support research and training. The database contains over 234 000 records, great attention paid to experimental data and uniform filling of the database for all atomic numbers Z, including classified levels and transitions of rare earth and transuranic elements and their ions. Original means of visualization of scientific data in the form of spectrograms and Grotrian diagrams have been proposed. Presentation of spectral data in the form of interactive color charts facilitates understanding and analysis of properties of atomic systems. The use of the spectral data of the IS ESA together with its functionality is effective for solving various scientific problems and training of specialists. (paper)

Electronic structure of atoms: atomic spectroscopy information system

Science.gov (United States)

Kazakov, V. V.; Kazakov, V. G.; Kovalev, V. S.; Meshkov, O. I.; Yatsenko, A. S.

2017-10-01

The article presents a Russian atomic spectroscopy, information system electronic structure of atoms (IS ESA) (http://grotrian.nsu.ru), and describes its main features and options to support research and training. The database contains over 234 000 records, great attention paid to experimental data and uniform filling of the database for all atomic numbers Z, including classified levels and transitions of rare earth and transuranic elements and their ions. Original means of visualization of scientific data in the form of spectrograms and Grotrian diagrams have been proposed. Presentation of spectral data in the form of interactive color charts facilitates understanding and analysis of properties of atomic systems. The use of the spectral data of the IS ESA together with its functionality is effective for solving various scientific problems and training of specialists.

Nonlocal electron kinetics and spectral line emission in the positive column of an argon glow discharge

International Nuclear Information System (INIS)

Golubovskii, Yu; Kalanov, D; Gorchakov, S; Uhrlandt, D

2015-01-01

Modern non-local electron kinetics theory predicts several interesting effects connected with spectral line emission from the positive column in the range of low and medium pressures and currents. Some theoretical works describe non-monotonic behavior of the radial profiles of line emission at intermediate pressures and currents between the validity ranges of the non-local and local approximation of the electron kinetics. Despite a great number of publications, there have been no systematic measurements attempting to confirm these theoretical predictions through experiments. In this work the radial profiles of the line emission from the positive column of an argon glow discharge have been measured with high spatial resolution and new effects caused by the narrowing and broadening of the spatial emission profiles with dependence on discharge conditions have been discovered. The effect of intensity maximum shift predicted by theory using a self-consistent model was not found in the experiment. The properties of the spectral line radiation are influenced by the peculiarities of the formation of the high-energy tail of the electron energy distribution function. An interpretation of the observed effects based on the non-local character of the electron kinetics in radially inhomogeneous fields is given. The obtained experimental data are compared with the results of calculations. (paper)

Time-dependent first-principles study of angle-resolved secondary electron emission from atomic sheets

Science.gov (United States)

Ueda, Yoshihiro; Suzuki, Yasumitsu; Watanabe, Kazuyuki

2018-02-01

Angle-resolved secondary electron emission (ARSEE) spectra were analyzed for two-dimensional atomic sheets using a time-dependent first-principles simulation of electron scattering. We demonstrate that the calculated ARSEE spectra capture the unoccupied band structure of the atomic sheets. The excitation dynamics that lead to SEE have also been revealed by the time-dependent Kohn-Sham decomposition scheme. In the present study, the mechanism for the experimentally observed ARSEE from atomic sheets is elucidated with respect to both energetics and the dynamical aspects of SEE.

ADAS: Atomic data, modelling and analysis for fusion

International Nuclear Information System (INIS)

Summers, H. P.; O'Mullane, M. G.; Whiteford, A. D.; Badnell, N. R.; Loch, S. D.

2007-01-01

The Atomic Data and Analysis Structure, ADAS, comprises extensive fundamental and derived atomic data collections, interactive codes for the manipulation and generation of collisional-radiative data and models, off-line codes for large scale fundamental atomic data production and codes for diagnostic analysis in the fusion and astrophysical environments. ADAS data are organized according to precise specifications, tuned to application and are assigned to numbered ADAS data formats. Some of these formats contain very large quantities of data and some have achieved wide-scale adoption in the fusion community.The paper focuses on recent extensions of ADAS designed to orient ADAS to the needs of ITER. The issue of heavy atomic species, expected to be present as ITER wall and divertor materials, dopants or control species, will be addressed with a view to the economized handling of the emission and ionisation state data needed for diagnostic spectral analysis. Charge exchange and beam emission spectroscopic capabilities and developments in ADAS will be reviewed from an ITER perspective and in the context of a shared analysis between fusion laboratories. Finally an overview and summary of current large scale fundamental data production in the framework of the ADAS project will be given and its intended availability in both fusion and astrophysics noted

Optimization of Fuel Consumption and Emissions for Auxiliary Power Unit Based on Multi-Objective Optimization Model

Directory of Open Access Journals (Sweden)

Yongpeng Shen

2016-02-01

Full Text Available Auxiliary power units (APUs are widely used for electric power generation in various types of electric vehicles, improvements in fuel economy and emissions of these vehicles directly depend on the operating point of the APUs. In order to balance the conflicting goals of fuel consumption and emissions reduction in the process of operating point choice, the APU operating point optimization problem is formulated as a constrained multi-objective optimization problem (CMOP firstly. The four competing objectives of this CMOP are fuel-electricity conversion cost, hydrocarbon (HC emissions, carbon monoxide (CO emissions and nitric oxide (NO x emissions. Then, the multi-objective particle swarm optimization (MOPSO algorithm and weighted metric decision making method are employed to solve the APU operating point multi-objective optimization model. Finally, bench experiments under New European driving cycle (NEDC, Federal test procedure (FTP and high way fuel economy test (HWFET driving cycles show that, compared with the results of the traditional fuel consumption single-objective optimization approach, the proposed multi-objective optimization approach shows significant improvements in emissions performance, at the expense of a slight drop in fuel efficiency.

Enhancement of electroplex emission by using multi-layer device structure

International Nuclear Information System (INIS)

Wang Yuanmin; Teng Feng; Xu Zheng; Hou Yanbing; Wang Yongsheng; Xu Xurong

2005-01-01

Electroplex emission based on poly(N-vinylcarbazole) (PVK) and 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP) has been improved dramatically by using a multi-layer device structure indium-tin oxide (ITO)/poly(3,4-ethylenedioxythiophene): poly(styrenesulphonic acid) (PEDOT:PSS)/PVK/BCP/PVK/BCP/LiF/Al. Electroplex emission at 595 nm has been improved about 10 times under low voltage and four times under high voltage compared to the double layer device ITO/PVK/BCP/Al. The maximum brightness of the device also has been improved about eight times. Bright white emission via electroplex formation can be obtained with Commission International d'Eclairage (CIE) coordinates (0.336, 0.320) at 26 V with a brightness of 123 cd/m 2 . Based on the analysis of highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) of the materials, we suggest the enhancement is mainly ascribed to the confinement effect of the quantum-well-like multi-layer device structure. Every hole and electron has more possibilities to cross recombination at the PVK/BCP interface

Enhancement of electroplex emission by using multi-layer device structure

Energy Technology Data Exchange (ETDEWEB)

Wang Yuanmin [Institute of Optoelectronic Technology, Beijing Jiaotong University, Beijing 100044 (China); Key Laboratory for Information Storage, Displays and Materials, Beijing 100044 (China); Teng Feng [Institute of Optoelectronic Technology, Beijing Jiaotong University, Beijing 100044 (China) and Key Laboratory for Information Storage, Displays and Materials, Beijing 100044 (China)]. E-mail: advanced9898@126.com; Xu Zheng [Institute of Optoelectronic Technology, Beijing Jiaotong University, Beijing 100044 (China); Key Laboratory for Information Storage, Displays and Materials, Beijing 100044 (China); Hou Yanbing [Institute of Optoelectronic Technology, Beijing Jiaotong University, Beijing 100044 (China); Key Laboratory for Information Storage, Displays and Materials, Beijing 100044 (China); Wang Yongsheng [Institute of Optoelectronic Technology, Beijing Jiaotong University, Beijing 100044 (China); Key Laboratory for Information Storage, Displays and Materials, Beijing 100044 (China); Xu Xurong [Institute of Optoelectronic Technology, Beijing Jiaotong University, Beijing 100044 (China); Key Laboratory for Information Storage, Displays and Materials, Beijing 100044 (China)

2005-04-30

Electroplex emission based on poly(N-vinylcarbazole) (PVK) and 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP) has been improved dramatically by using a multi-layer device structure indium-tin oxide (ITO)/poly(3,4-ethylenedioxythiophene): poly(styrenesulphonic acid) (PEDOT:PSS)/PVK/BCP/PVK/BCP/LiF/Al. Electroplex emission at 595 nm has been improved about 10 times under low voltage and four times under high voltage compared to the double layer device ITO/PVK/BCP/Al. The maximum brightness of the device also has been improved about eight times. Bright white emission via electroplex formation can be obtained with Commission International d'Eclairage (CIE) coordinates (0.336, 0.320) at 26 V with a brightness of 123 cd/m{sup 2}. Based on the analysis of highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) of the materials, we suggest the enhancement is mainly ascribed to the confinement effect of the quantum-well-like multi-layer device structure. Every hole and electron has more possibilities to cross recombination at the PVK/BCP interface.

Magnetic linear dichroism in x-ray emission spectroscopy: Yb in Yb3 Fe5 O12

NARCIS (Netherlands)

Groot, F.M.F. de; Krisch, M.H.; Sette, F.; Vogel, J.

2000-01-01

A magnetic linear dichroism MLD effect of up to 5% has been observed in the 2p 1/2 4d x-ray emission spectrum of Yb in Yb 3 Fe 5 O 12 . The spectral shape is well reproduced with an atomic multiplet calculation of the 4d to 2p decay. It is shown that the details of the spectral shapes are

IDEN2-A program for visual identification of spectral lines and energy levels in optical spectra of atoms and simple molecules

Science.gov (United States)

Azarov, V. I.; Kramida, A.; Vokhmentsev, M. Ya.

2018-04-01

The article describes a Java program that can be used in a user-friendly way to visually identify spectral lines observed in complex spectra with theoretically predicted transitions between atomic or molecular energy levels. The program arranges various information about spectral lines and energy levels in such a way that line identification and determination of positions of experimentally observed energy levels become much easier tasks that can be solved fast and efficiently.

Emission spectral analysis of nickel-base superalloys with fixed time intergration technique

International Nuclear Information System (INIS)

Okochi, Haruno; Takahashi, Katsuyuki; Suzuki, Shunichi; Sudo, Emiko

1980-01-01

Simultaneous determination of multielements (C, B, Mo, Ta, Co, Fe, Mn, Cr, Nb, Cu, Ti, Zr, and Al) in nickel-base superalloys (Ni: 68 -- 76%) was performed by emission spectral analysis. At first, samples which had various nickel contents (ni: 68 -- 76%) were prepared by using JAERI R9, nickel and other metals (Fe, Co, or Cr). It was confirmed that in the internal standard method (Ni II 227.73 nm), analytical values of all the elements examined decreased with a decrease of the integration time (ca. 3.9 -- 4.6 s), that is, an increase of the nickel content. On the other hand, according to the fixed time integration method, elements except for C, Mo, and Cr were not interfered within the range of nickel contents examined. A series of nickel-base binary alloys (Al, Si, Ti, Cr, Mn, Fe, Co, Nb, Mo, and W series) were prepared by high frequency induction melting and the centrifugal casting method and formulae for correcting interferences with near spectral lines were obtained. Various synthetic samples were prepared and analysed by this method. The equations of calibration curves were derived from the data for standard samples (JAERI R1 -- R6, NBS 1189, 1203 -- 1205, and B.S. 600B) by curve fitting with orthogonal polynomials using a computer. For the assessment of this method studied, the F-test was performed by comparison of variances of both analytical values of standard and synthetic samples. The surfaces of specimens were polished with a belt grinder using No. 80 of alumina or silicon carbide endless-paper. The preburn period and integration one were decided at 5 and 6 s respectively. A few standard samples which gave worse reproducibility in emission spectral analysis was investigated with an optical microscope and an electron probe X-ray microanalyser. (author)

Multi-lateral emission trading: lessons from inter-state NOx control in the United States

International Nuclear Information System (INIS)

Farrell, A.

2001-01-01

Marketable emission permit mechanisms are increasingly proposed as efficient means of managing environmental pollution problems such as greenhouse gas emissions. Existing examples of emissions trading in the literature have so far been limited to domestic efforts put in place through the action of a national legislature, which has no parallel in international politics. This paper examines two efforts to establish multi-lateral emissions trading for nitrogen oxides among various states with the US. One, the Ozone Transport Commission's NO x Budget program is a success. The other, the Ozone Transport Assessment Group and the federal government's subsequent NO x SIP Call has not resulted in a multi-lateral emissions control program, let alone an efficient, market-based one. Due to the relative similarities of the states (compared to highly heterogeneous nations of the world) these are ''best case'' examples, and explaining the vast differences in outcomes will help explain the potential and the challenges in developing an international emission trading program to control greenhouse gas emissions. (author)

Atomic Data for the CHIANTI Database

Science.gov (United States)

Bhatia, Anand K.; Landi, E.

2012-01-01

The CHIANTI spectral code consists of an atomic database and a suite of computer programs to calculate the optically thin spectrum of astrophysical objects and to carry out spectroscopic plasma diagnostics. The database includes atomic energy levels, wavelengths, radiative transition rates, collisional excitation, ionization and recombination rate coefficients, as well as data to calculate free-free, free-bound and two-photon continuum emission. In recent years, we have been pursuing a program to calculate atomic data for ions whose lines have been observed in astrophysical spectra but have been neglected in the literature, and to provide CHIANTI with all the data necessary to predict line intensities. There are two types of such ions: those for which calculations are available for low-energy configurations but not for high-energy configurations (i.e., C-like, N-like, O-like systems), and ions that have never or only seldom been studied. This poster will summarize the current status of this project and indicate the future activities .

Fourier transform infrared emission spectra of atomic rubidium: g- and h-states

Czech Academy of Sciences Publication Activity Database

Civiš, Svatopluk; Ferus, Martin; Kubelík, Petr; Chernov, Vladislav E.; Zanozina, Ekaterina M.

2012-01-01

Roč. 45, č. 17 (2012), s. 175002 ISSN 0953-4075 R&D Projects: GA AV ČR IAAX00100903 Institutional support: RVO:61388955 Keywords : Fourier transform infrared emission spectra * atomic rubidium * physical chemistry Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.031, year: 2012

Optical emission studies of atomic and ionic species in the ionized sputter-deposition process of magnesium oxide thin films

International Nuclear Information System (INIS)

Matsuda, Y.; Koyama, Y.; Iwaya, M.; Shinohara, M.; Fujiyama, H.

2005-01-01

Planar magnetron (PM) power and ICP-RF power dependences of the optical emission intensities of excited atomic and ionic species in the reactive ionized sputter-deposition of magnesium oxide (MgO) thin films were investigated. With the increase in PM power at constant ICP-RF power, Mg I emission intensity increased and Ar I emission intensity gradually decreased. With the increase in ICP-RF power at constant PM power, the Mg I emission intensity increased at lower ICP-RF power and then gradually decreased at higher ICP-RF power; on the contrary, Ar I emission intensity monotonically increased. Emission intensity of atomic oxygen was negligibly small compared with those of Mg I and Ar I under the metallic sputtering mode condition

Normal spectral emissivity of selected liquid metals and improved thermophysical properties

International Nuclear Information System (INIS)

Pottlacher, G.; Seifter, A.

2001-01-01

Full Text: Emissivity measurements on several liquid metals up to temperatures of 6000 K have been successfully established by linking a laser polarimetry technique to our well-known method for performing high speed measurements of thermophysical properties on liquid metal samples during microsecond pulse-heating experiments. Thermophysical properties measured with our experimental setup include temperature dependencies of heat capacity, enthalpy, electrical resistivity, density, thermal diffusivity and thermal conductivity up to the end of the stable liquid phase. During grant P12775-PHY additionally to the above listened properties the measurement of the change of the polarization of laser light reflected from the surface during pulse heating was enabled and thus now the temperature dependence of spectral emissivity at 684.5 nm by methods of ellipsometry is derived also. Several liquid metals and alloys have been investigated within this grant and a review of the data obtained will be given here. (author)

Determination of Metals Present in Textile Dyes Using Laser-Induced Breakdown Spectroscopy and Cross-Validation Using Inductively Coupled Plasma/Atomic Emission Spectroscopy

Directory of Open Access Journals (Sweden)

K. Rehan

2017-01-01

Full Text Available Laser-induced breakdown spectroscopy (LIBS was used for the quantitative analysis of elements present in textile dyes at ambient pressure via the fundamental mode (1064 nm of a Nd:YAG pulsed laser. Three samples were collected for this purpose. Spectra of textile dyes were acquired using an HR spectrometer (LIBS2000+, Ocean Optics, Inc. having an optical resolution of 0.06 nm in the spectral range of 200 to 720 nm. Toxic metals like Cr, Cu, Fe, Ni, and Zn along with other elements like Al, Mg, Ca, and Na were revealed to exist in the samples. The %-age concentrations of the detected elements were measured by means of standard calibration curve method, intensities of every emission from every species, and calibration-free (CF LIBS approach. Only Sample 3 was found to contain heavy metals like Cr, Cu, and Ni above the prescribed limit. The results using LIBS were found to be in good agreement when compared to outcomes of inductively coupled plasma/atomic emission spectroscopy (ICP/AES.

Application of the three-component bidirectional reflectance distribution function model to Monte Carlo calculation of spectral effective emissivities of nonisothermal blackbody cavities.

Science.gov (United States)

Prokhorov, Alexander; Prokhorova, Nina I

2012-11-20

We applied the bidirectional reflectance distribution function (BRDF) model consisting of diffuse, quasi-specular, and glossy components to the Monte Carlo modeling of spectral effective emissivities for nonisothermal cavities. A method for extension of a monochromatic three-component (3C) BRDF model to a continuous spectral range is proposed. The initial data for this method are the BRDFs measured in the plane of incidence at a single wavelength and several incidence angles and directional-hemispherical reflectance measured at one incidence angle within a finite spectral range. We proposed the Monte Carlo algorithm for calculation of spectral effective emissivities for nonisothermal cavities whose internal surface is described by the wavelength-dependent 3C BRDF model. The results obtained for a cylindroconical nonisothermal cavity are discussed and compared with results obtained using the conventional specular-diffuse model.

Spectral characteristics of 2-(4'-amino-3-pyridyl)benzimidazole: Effects of solvent and acid or base concentration

International Nuclear Information System (INIS)

Dogra, Sneh K.

2006-01-01

Spectral characteristics of 2-(4'-amino-3-pyridyl)benzimidazole (4-A3PyBI) have been studied in different solvents, as well as at different acid or base concentrations using absorption, fluorescence excitation and fluorescence spectroscopy. Excited singlet state (S 1 ) lifetimes for each species were measured using nanosecond time-dependent spectrofluorimeter. AM1 semi-empirical and density functional theoretical (DFT) calculations were performed on each species for the spectral assignment. From the above results it is concluded that 4-A3PyBI exists only in the amine form. First protonation occurs at pyridine=N- atom and second protonation at the benzimidazole (BI)=N- atom. When dication (DC) species is excited, two emission bands are observed, having the same fluorescence excitation spectra, suggesting the same ground state (S ) precursor. Short wavelength (SW) emission band is assigned to the π-π* transition and long wavelength (LW) emission to the charge transfer transition. First deprotonation in S state occurs from >N-H moiety, whereas in S 1 state it is from -NH 2 group. Monoanion (MA) so formed in S 1 state is non-fluorescent. Dianion (DA) is formed by further deprotonating >N-H moiety in S 1 state and it is fluorescent. pK a values were determined and discussed

Atomically thin resonant tunnel diodes built from synthetic van der Waals heterostructures

KAUST Repository

Lin, Yu-Chuan; Ghosh, Ram Krishna; Addou, Rafik; Lu, Ning; Eichfeld, Sarah M.; Zhu, Hui; Li, Ming-Yang; Peng, Xin; Kim, Moon J.; Li, Lain-Jong; Wallace, Robert M.; Datta, Suman; Robinson, Joshua A.

2015-01-01

Vertical integration of two-dimensional van der Waals materials is predicted to lead to novel electronic and optical properties not found in the constituent layers. Here, we present the direct synthesis of two unique, atomically thin, multi-junction heterostructures by combining graphene with the monolayer transition-metal dichalcogenides: molybdenum disulfide (MoS2), molybdenum diselenide (MoSe2) and tungsten diselenide (WSe2). The realization of MoS2–WSe2–graphene and WSe2–MoS2–graphene heterostructures leads to resonant tunnelling in an atomically thin stack with spectrally narrow, room temperature negative differential resistance characteristics.

Atomically thin resonant tunnel diodes built from synthetic van der Waals heterostructures

KAUST Repository

Lin, Yu-Chuan

2015-06-19

Vertical integration of two-dimensional van der Waals materials is predicted to lead to novel electronic and optical properties not found in the constituent layers. Here, we present the direct synthesis of two unique, atomically thin, multi-junction heterostructures by combining graphene with the monolayer transition-metal dichalcogenides: molybdenum disulfide (MoS2), molybdenum diselenide (MoSe2) and tungsten diselenide (WSe2). The realization of MoS2–WSe2–graphene and WSe2–MoS2–graphene heterostructures leads to resonant tunnelling in an atomically thin stack with spectrally narrow, room temperature negative differential resistance characteristics.

Double differential distributions of electron emission in ion-atom and electron-atom collisions using an electron spectrometer

International Nuclear Information System (INIS)

Misra, Deepankar; Thulasiram, K.V.; Fernandes, W.; Kelkar, Aditya H.; Kadhane, U.; Kumar, Ajay; Singh, Yeshpal; Gulyas, L.; Tribedi, Lokesh C.

2009-01-01

We study electron emission from atoms and molecules in collisions with fast electrons and heavy ions (C 6+ ). The soft collision electrons (SE), two center electron emission (TCEE), the binary encounter (BE) events and the KLL Auger lines along with the elastically scattered peaks (in electron collisions) are studied using a hemispherical electrostatic electron analyzer. The details of the measurements along with description of the spectrometer and data acquisition system are given. The angular distributions of the low energy (few eV) electrons in soft collisions and the binary encounter electrons at keV energies are compared with quantum mechanical models based on the first Born (B1) and the continuum distorted wave-Eikonal initial state approximation (CDW-EIS).

A multi-objective programming model for assessment the GHG emissions in MSW management

Energy Technology Data Exchange (ETDEWEB)

Mavrotas, George, E-mail: mavrotas@chemeng.ntua.gr [National Technical University of Athens, Iroon Polytechniou 9, Zografou, Athens, 15780 (Greece); Skoulaxinou, Sotiria [EPEM SA, 141 B Acharnon Str., Athens, 10446 (Greece); Gakis, Nikos [FACETS SA, Agiou Isidorou Str., Athens, 11471 (Greece); Katsouros, Vassilis [Athena Research and Innovation Center, Artemidos 6 and Epidavrou Str., Maroussi, 15125 (Greece); Georgopoulou, Elena [National Observatory of Athens, Thisio, Athens, 11810 (Greece)

2013-09-15

Highlights: • The multi-objective multi-period optimization model. • The solution approach for the generation of the Pareto front with mathematical programming. • The very detailed description of the model (decision variables, parameters, equations). • The use of IPCC 2006 guidelines for landfill emissions (first order decay model) in the mathematical programming formulation. - Abstract: In this study a multi-objective mathematical programming model is developed for taking into account GHG emissions for Municipal Solid Waste (MSW) management. Mathematical programming models are often used for structure, design and operational optimization of various systems (energy, supply chain, processes, etc.). The last twenty years they are used all the more often in Municipal Solid Waste (MSW) management in order to provide optimal solutions with the cost objective being the usual driver of the optimization. In our work we consider the GHG emissions as an additional criterion, aiming at a multi-objective approach. The Pareto front (Cost vs. GHG emissions) of the system is generated using an appropriate multi-objective method. This information is essential to the decision maker because he can explore the trade-offs in the Pareto curve and select his most preferred among the Pareto optimal solutions. In the present work a detailed multi-objective, multi-period mathematical programming model is developed in order to describe the waste management problem. Apart from the bi-objective approach, the major innovations of the model are (1) the detailed modeling considering 34 materials and 42 technologies, (2) the detailed calculation of the energy content of the various streams based on the detailed material balances, and (3) the incorporation of the IPCC guidelines for the CH{sub 4} generated in the landfills (first order decay model). The equations of the model are described in full detail. Finally, the whole approach is illustrated with a case study referring to the

A multi-objective programming model for assessment the GHG emissions in MSW management

International Nuclear Information System (INIS)

Mavrotas, George; Skoulaxinou, Sotiria; Gakis, Nikos; Katsouros, Vassilis; Georgopoulou, Elena

2013-01-01

Highlights: • The multi-objective multi-period optimization model. • The solution approach for the generation of the Pareto front with mathematical programming. • The very detailed description of the model (decision variables, parameters, equations). • The use of IPCC 2006 guidelines for landfill emissions (first order decay model) in the mathematical programming formulation. - Abstract: In this study a multi-objective mathematical programming model is developed for taking into account GHG emissions for Municipal Solid Waste (MSW) management. Mathematical programming models are often used for structure, design and operational optimization of various systems (energy, supply chain, processes, etc.). The last twenty years they are used all the more often in Municipal Solid Waste (MSW) management in order to provide optimal solutions with the cost objective being the usual driver of the optimization. In our work we consider the GHG emissions as an additional criterion, aiming at a multi-objective approach. The Pareto front (Cost vs. GHG emissions) of the system is generated using an appropriate multi-objective method. This information is essential to the decision maker because he can explore the trade-offs in the Pareto curve and select his most preferred among the Pareto optimal solutions. In the present work a detailed multi-objective, multi-period mathematical programming model is developed in order to describe the waste management problem. Apart from the bi-objective approach, the major innovations of the model are (1) the detailed modeling considering 34 materials and 42 technologies, (2) the detailed calculation of the energy content of the various streams based on the detailed material balances, and (3) the incorporation of the IPCC guidelines for the CH 4 generated in the landfills (first order decay model). The equations of the model are described in full detail. Finally, the whole approach is illustrated with a case study referring to the application

Atomic physics with highly charged ions. Progress report

Energy Technology Data Exchange (ETDEWEB)

Richard, P.

1994-08-01

The study of inelastic collision phenomena with highly charged projectile ions and the interpretation of spectral features resulting from these collisions remain as the major focal points in the atomic physics research at the J.R. Macdonald Laboratory, Kansas State University, Manhattan, Kansas. The title of the research project, ``Atomic Physics with Highly Charged Ions,`` speaks to these points. The experimental work in the past few years has divided into collisions at high velocity using the primary beams from the tandem and LINAC accelerators and collisions at low velocity using the CRYEBIS facility. Theoretical calculations have been performed to accurately describe inelastic scattering processes of the one-electron and many-electron type, and to accurately predict atomic transition energies and intensities for x rays and Auger electrons. Brief research summaries are given for the following: (1) electron production in ion-atom collisions; (2) role of electron-electron interactions in two-electron processes; (3) multi-electron processes; (4) collisions with excited, aligned, Rydberg targets; (5) ion-ion collisions; (6) ion-molecule collisions; (7) ion-atom collision theory; and (8) ion-surface interactions.

X-ray spectral study of the Th6p,5f electron states in ThO2 and ThF4

International Nuclear Information System (INIS)

Teterin, Y.A.; Nikitin, A.S.; Teterin, A.Y.; Ivanov, K.E.; Utkin, I.O.; Nerehov, V.A.; Ryzhkov, M.V.; Vukchevich, I.J.

2002-01-01

The study of the Th6p,5f electron states in Th, ThO 2 and ThF was carried out on the basis of the X-ray photoelectron fine spectral structure parameters in the binding energy range of 0-∼ 1000 eV, X-ray O 4,5 (Th) emission spectra of the shallow (0-∼50 eV) electrons and results of theoretical calculations. As a result, despite the absence of the Th5f electrons in thorium atoms, the Th5f atomic orbitals were established to participate in the formation of molecular orbitals in thorium dioxide and tetrafluoride. In the MO LCAO approximation this allowed to suggest the possible existence of filled Th5f electronic states in thorium compounds. On the basis of the X-ray O 4,5 (Th) emission spectral structure parameters the effective formation of the inner valence molecular orbitals in the studied compounds was confirmed. (authors)

Multi-band morpho-Spectral Component Analysis Deblending Tool (MuSCADeT): Deblending colourful objects

Science.gov (United States)

Joseph, R.; Courbin, F.; Starck, J.-L.

2016-05-01

We introduce a new algorithm for colour separation and deblending of multi-band astronomical images called MuSCADeT which is based on Morpho-spectral Component Analysis of multi-band images. The MuSCADeT algorithm takes advantage of the sparsity of astronomical objects in morphological dictionaries such as wavelets and their differences in spectral energy distribution (SED) across multi-band observations. This allows us to devise a model independent and automated approach to separate objects with different colours. We show with simulations that we are able to separate highly blended objects and that our algorithm is robust against SED variations of objects across the field of view. To confront our algorithm with real data, we use HST images of the strong lensing galaxy cluster MACS J1149+2223 and we show that MuSCADeT performs better than traditional profile-fitting techniques in deblending the foreground lensing galaxies from background lensed galaxies. Although the main driver for our work is the deblending of strong gravitational lenses, our method is fit to be used for any purpose related to deblending of objects in astronomical images. An example of such an application is the separation of the red and blue stellar populations of a spiral galaxy in the galaxy cluster Abell 2744. We provide a python package along with all simulations and routines used in this paper to contribute to reproducible research efforts. Codes can be found at http://lastro.epfl.ch/page-126973.html

Multi-band emission in a wide wavelength range from tin oxide/Au nanocomposites grown on porous anodic alumina substrate (AAO)

International Nuclear Information System (INIS)

Norek, Małgorzata; Michalska-Domańska, Marta; Stępniowski, Wojciech J.; Ayala, Israel; Bombalska, Aneta; Budner, Bogusław

2013-01-01

The photoluminescence (PL) properties of tin oxide nanostructures are investigated. Three samples of different morphology, induced by deposition process and various geometrical features of nanoporous anodic aluminum oxide (AAO) substrate, are analyzed. X-ray photoelectronic spectroscopy (XPS) analysis reveals the presence of two forms of tin oxide on the surface of all studied samples: SnO and SnO 2 . The former form is typical for reduced surface with bridging oxygen atoms and every other row of in-plane oxygen atoms removed. The oxygen defects give rise to a strong emission in visible region. Two intense PL peaks are observed centered at about 540 (band I) and 620 (band II) nm. The origin of these bands was ascribed to the recombination of electrons from the conduction band (band I) and shallow traps levels (band II) to the surface oxygen vacancy levels. Upon deposition of Au nanoparticles on the top of tin oxide nanostructures the emission at 540 and 620 nm disappears and a new band (band III) occurs in the range >760 nm. The PL mechanism operating in the studied systems is discussed. The tin oxide/Au nanocomposites can be used as efficient multi-band light emitters in a wide (from visible to near infrared) wavelength range.

Beyond Low-Rank Representations: Orthogonal clustering basis reconstruction with optimized graph structure for multi-view spectral clustering.

Science.gov (United States)

Wang, Yang; Wu, Lin

2018-07-01

Low-Rank Representation (LRR) is arguably one of the most powerful paradigms for Multi-view spectral clustering, which elegantly encodes the multi-view local graph/manifold structures into an intrinsic low-rank self-expressive data similarity embedded in high-dimensional space, to yield a better graph partition than their single-view counterparts. In this paper we revisit it with a fundamentally different perspective by discovering LRR as essentially a latent clustered orthogonal projection based representation winged with an optimized local graph structure for spectral clustering; each column of the representation is fundamentally a cluster basis orthogonal to others to indicate its members, which intuitively projects the view-specific feature representation to be the one spanned by all orthogonal basis to characterize the cluster structures. Upon this finding, we propose our technique with the following: (1) We decompose LRR into latent clustered orthogonal representation via low-rank matrix factorization, to encode the more flexible cluster structures than LRR over primal data objects; (2) We convert the problem of LRR into that of simultaneously learning orthogonal clustered representation and optimized local graph structure for each view; (3) The learned orthogonal clustered representations and local graph structures enjoy the same magnitude for multi-view, so that the ideal multi-view consensus can be readily achieved. The experiments over multi-view datasets validate its superiority, especially over recent state-of-the-art LRR models. Copyright © 2018 Elsevier Ltd. All rights reserved.

Influence of the number of atomic levels on the spectral opacity of low temperature nickel and iron in the spectral range 50-300 eV

International Nuclear Information System (INIS)

Busquet, M.; Klapisch, M.; Gilles, D.

2013-01-01

Opacity is a fundamental ingredient for the secular evolution of stars. The calculation of the stellar plasma absorption coefficients is complex due to the composition of these plasmas, generally an H /He dominated mixture with a low concentration of partially ionized heavy ions (the iron group). The international collaboration OPAC recently presented extensive comparisons of spectral opacities of iron and nickel for temperatures between 15 and 40 eV and for densities of ∼ 3 mg/cm 3 , relevant to the stellar envelope conditions [1, 2]. The role of Configuration Interaction (CI) and the influence of the number of atomic levels on the opacity using the recently improved version of HULLAC atomic code [3, 4] are illustrated in this article. Comparisons with theoretical predictions already presented in [1] are discussed. (authors)

Ultra fast atomic process in X-ray emission by inner-shell ionization

Energy Technology Data Exchange (ETDEWEB)

Moribayashi, Kengo; Sasaki, Akira [Japan Atomic Energy Research Inst., Neyagawa, Osaka (Japan). Kansai Research Establishment; Tajima, T

1998-03-01

An ultra-fast atomic process together with X-ray emission by inner-shell ionization using high intensity (10{sup 18} W/cm{sup 2}) short pulse (20fs) X-ray is studied. A new class of experiment is proposed and a useful pumping source is suggested. In this method, it is found that the gain value of X-ray laser amounts to larger than 1000(1/cm) with use of the density of 10{sup 22}/cm{sup 3} of carbon atom. Electron impact ionization effect and initial density effect as well as intensity of pumping source effect are also discussed. (author)

Spectral signatures of fluorescence and light absorption to identify crude oils found in the marine environment

Science.gov (United States)

Baszanowska, E.; Otremba, Z.

2014-08-01

To protect the natural marine ecosystem, it is necessary to continuously enhance knowledge of environmental contamination, including oil pollution. Therefore, to properly track the qualitative and quantitative changes in the natural components of seawater, a description of the essential spectral features describing petroleum products is necessary. This study characterises two optically-different types of crude oils (Petrobaltic and Romashkino) - substances belonging to multi-fluorophoric systems. To obtain the spectral features of crude oils, the excitation-emission spectroscopy technique was applied. The fluorescence and light absorption properties for various concentrations of oils at a stabilised temperature are described. Both excitation-emission spectra (EEMs) and absorption spectra of crude oils are discussed. Based on the EEM spectra, both excitation end emission peaks for the wavelengthindependent fluorescence maximum (Exmax/ Emmax) - characteristic points for each type of oil - were identified and compared with the literature data concerning typical marine chemical structures.

Effectiveness of multi-stage scrubbers in reducing emissions of air pollutants from pig houses

OpenAIRE

Zhao, Y.; Aarnink, A.J.A.; Jong, de, M.C.M.; Ogink, N.W.M.; Groot Koerkamp, P.W.G.

2011-01-01

Emissions of air pollutants from livestock houses may raise environmental problems and pose hazards to public health. They can be reduced by scrubbers installed at the air outlets of livestock houses. In this study, three multi-stage scrubbers were evaluated in terms of their effectiveness in reducing emissions of airborne dust, total bacteria, ammonia, and CO2 from pig houses in winter. The three multi-stage scrubbers were one double-stage scrubber (acid stage+ bio-filter), one double-stage ...

Radar Precoder Design for Spectral Coexistence with Coordinated Multi-point (CoMP) System

OpenAIRE

Mahal, Jasmin A.; Khawar, Awais; Abdelhadi, Ahmed; Clancy, T. Charles

2015-01-01

This paper details the design of precoders for a MIMO radar spectrally coexistent with a MIMO cellular network. We focus on a coordinated multi-point (CoMP) system where a cluster of base stations (BSs) coordinate their transmissions to the intended user. The radar operates in two modes, interference-mitigation mode when it avoids interference with the CoMP system and cooperation mode when it exchanges information with it. Using either the conventional Switched Null Space Projection (SNSP) or...

The Impact of Quantitative Data Provided by a Multi-spectral Digital Skin Lesion Analysis Device on Dermatologists'Decisions to Biopsy Pigmented Lesions.

Science.gov (United States)

Farberg, Aaron S; Winkelmann, Richard R; Tucker, Natalie; White, Richard; Rigel, Darrell S

2017-09-01

BACKGROUND: Early diagnosis of melanoma is critical to survival. New technologies, such as a multi-spectral digital skin lesion analysis (MSDSLA) device [MelaFind, STRATA Skin Sciences, Horsham, Pennsylvania] may be useful to enhance clinician evaluation of concerning pigmented skin lesions. Previous studies evaluated the effect of only the binary output. OBJECTIVE: The objective of this study was to determine how decisions dermatologists make regarding pigmented lesion biopsies are impacted by providing both the underlying classifier score (CS) and associated probability risk provided by multi-spectral digital skin lesion analysis. This outcome was also compared against the improvement reported with the provision of only the binary output. METHODS: Dermatologists attending an educational conference evaluated 50 pigmented lesions (25 melanomas and 25 benign lesions). Participants were asked if they would biopsy the lesion based on clinical images, and were asked this question again after being shown multi-spectral digital skin lesion analysis data that included the probability graphs and classifier score. RESULTS: Data were analyzed from a total of 160 United States board-certified dermatologists. Biopsy sensitivity for melanoma improved from 76 percent following clinical evaluation to 92 percent after quantitative multi-spectral digital skin lesion analysis information was provided ( p quantitative data were provided. Negative predictive value also increased (68% vs. 91%, panalysis (64% vs. 86%, p data into physician evaluation of pigmented lesions led to both increased sensitivity and specificity, thereby resulting in more accurate biopsy decisions.

Portable laser synthesizer for high-speed multi-dimensional spectroscopy

Science.gov (United States)

Demos, Stavros G [Livermore, CA; Shverdin, Miroslav Y [Sunnyvale, CA; Shirk, Michael D [Brentwood, CA

2012-05-29

Portable, field-deployable laser synthesizer devices designed for multi-dimensional spectrometry and time-resolved and/or hyperspectral imaging include a coherent light source which simultaneously produces a very broad, energetic, discrete spectrum spanning through or within the ultraviolet, visible, and near infrared wavelengths. The light output is spectrally resolved and each wavelength is delayed with respect to each other. A probe enables light delivery to a target. For multidimensional spectroscopy applications, the probe can collect the resulting emission and deliver this radiation to a time gated spectrometer for temporal and spectral analysis.

Mutual information registration of multi-spectral and multi-resolution images of DigitalGlobe's WorldView-3 imaging satellite

Science.gov (United States)

Miecznik, Grzegorz; Shafer, Jeff; Baugh, William M.; Bader, Brett; Karspeck, Milan; Pacifici, Fabio

2017-05-01

WorldView-3 (WV-3) is a DigitalGlobe commercial, high resolution, push-broom imaging satellite with three instruments: visible and near-infrared VNIR consisting of panchromatic (0.3m nadir GSD) plus multi-spectral (1.2m), short-wave infrared SWIR (3.7m), and multi-spectral CAVIS (30m). Nine VNIR bands, which are on one instrument, are nearly perfectly registered to each other, whereas eight SWIR bands, belonging to the second instrument, are misaligned with respect to VNIR and to each other. Geometric calibration and ortho-rectification results in a VNIR/SWIR alignment which is accurate to approximately 0.75 SWIR pixel at 3.7m GSD, whereas inter-SWIR, band to band registration is 0.3 SWIR pixel. Numerous high resolution, spectral applications, such as object classification and material identification, require more accurate registration, which can be achieved by utilizing image processing algorithms, for example Mutual Information (MI). Although MI-based co-registration algorithms are highly accurate, implementation details for automated processing can be challenging. One particular challenge is how to compute bin widths of intensity histograms, which are fundamental building blocks of MI. We solve this problem by making the bin widths proportional to instrument shot noise. Next, we show how to take advantage of multiple VNIR bands, and improve registration sensitivity to image alignment. To meet this goal, we employ Canonical Correlation Analysis, which maximizes VNIR/SWIR correlation through an optimal linear combination of VNIR bands. Finally we explore how to register images corresponding to different spatial resolutions. We show that MI computed at a low-resolution grid is more sensitive to alignment parameters than MI computed at a high-resolution grid. The proposed modifications allow us to improve VNIR/SWIR registration to better than ¼ of a SWIR pixel, as long as terrain elevation is properly accounted for, and clouds and water are masked out.

Composite multi-lobe descriptor for cross spectral face recognition: matching active IR to visible light images

Science.gov (United States)

Cao, Zhicheng; Schmid, Natalia A.

2015-05-01

Matching facial images across electromagnetic spectrum presents a challenging problem in the field of biometrics and identity management. An example of this problem includes cross spectral matching of active infrared (IR) face images or thermal IR face images against a dataset of visible light images. This paper describes a new operator named Composite Multi-Lobe Descriptor (CMLD) for facial feature extraction in cross spectral matching of near-infrared (NIR) or short-wave infrared (SWIR) against visible light images. The new operator is inspired by the design of ordinal measures. The operator combines Gaussian-based multi-lobe kernel functions, Local Binary Pattern (LBP), generalized LBP (GLBP) and Weber Local Descriptor (WLD) and modifies them into multi-lobe functions with smoothed neighborhoods. The new operator encodes both the magnitude and phase responses of Gabor filters. The combining of LBP and WLD utilizes both the orientation and intensity information of edges. Introduction of multi-lobe functions with smoothed neighborhoods further makes the proposed operator robust against noise and poor image quality. Output templates are transformed into histograms and then compared by means of a symmetric Kullback-Leibler metric resulting in a matching score. The performance of the multi-lobe descriptor is compared with that of other operators such as LBP, Histogram of Oriented Gradients (HOG), ordinal measures, and their combinations. The experimental results show that in many cases the proposed method, CMLD, outperforms the other operators and their combinations. In addition to different infrared spectra, various standoff distances from close-up (1.5 m) to intermediate (50 m) and long (106 m) are also investigated in this paper. Performance of CMLD is evaluated for of each of the three cases of distances.

A new experimental apparatus for emissivity measurements of steel and the application of multi-wavelength thermometry to continuous casting billets

Science.gov (United States)

Wang, Peng; Hu, Zhenwei; Xie, Zhi; Yan, Ming

2018-05-01

An experimental apparatus has been designed for measuring the emissivity of a steel surface in both vacuum and oxidation atmosphere. The sample is heated with the method of electromagnetic induction in order to ensure the temperature uniformity. The radiance emitted from a sample is measured using a fiber-optic Fourier transform infrared spectrometer. Using this unique apparatus, we investigated the spectral (2-6 μm) and directional (0°-86°) emissivity of stainless steel 304 with different degrees of surface oxidation at temperatures ranging from 800 to 1100 °C. The experimental results show that the emissivity increases slightly with increasing temperature, which accords with the Hagen-Rubens relation. The emissivity increases rapidly at the initial stage of oxidation, but gradually reaches to a constant value after 20 min. In addition, the directional emissivity has a maximum value at the measuring angle of about 75°. The maximum uncertainty of emissivity is only 3.0% over all the measuring ranges, indicating that this experimental apparatus has a high reliability. In order to measure the surface temperature of casting billets based on multi-wavelength thermometry, the bivariate emissivity function with the two variables, wavelength and temperature, is determined. Temperature measurement results based on our technique are compared with those from common dual-wavelength radiation thermometry. Our approach reduces the measured temperature fluctuation from ±20.7 °C to ±2.8 °C and reflects the temperature variation with the changes of production parameters in real time.

Inductively coupled plasma--atomic emission spectroscopy: an evaluation of the use of nitrogen--argon admixtures as plasma discharge atmospheres

International Nuclear Information System (INIS)

Zalewski, J.C.

1979-01-01

The effects of the use of nitrogen in either the plasma coolant or aerosol carrier gas flows on the physical and spectrochemical properties of the inductively coupled plasma (ICP) were examined. While the plasma operated with nitrogen in the coolant flow exhibited a stability comparable to that of the argon plasma, the use of nitrogen in the aerosol carrier gas flow resulted in a plasma that was less stable. The detection limits obtained for the three plasmas exhibited a similar trend. In addition, the use of nitrogen--argon admixtures in the plasma coolant gas flow yielded an increase in both the net analyte and the background emission intensities when the corresponding argon and nitrogen--argon plasmas were operated under various conditions. Furthermore, the effect of aluminum on the Ca II (393.4 nm) spectral line was reported for the 1000/1 Al/Ca molar ratio. At an observation height of 15 mm, the signal depressions were 4 and 14% for the nitrogen--argon and the argon plasmas, respectively. The above experimental evidence suggested that the operation of the ICP with an Ar--N 2 coolant gas might be hotter than the argon plasma currently in use in this laboratory. The demountable plasma torch designed in collaboration with K. Olson yielded detection limits for 15 elements and 19 spectral lines that were approximately within a factor of two of those obtained with the torch of fused quartz design. The design also appeared to offer a more readily initiated plasma discharge. The experimental evidence presented supports the utilization of nitrogen--argon admixtures in the plasma coolant gas flow as alternate discharge atmospheres for inductively coupled plasma--atomic emission spectroscopy. In contrast, the experimental evidence shows that there is a deterioration in both physical and spectrochemical properties of plasmas operated with a nitrogen aerosol carrier gas

Abatement Costs vs. Compliance Costs in Multi-Period Emissions Trading - The Firms' Perspective

OpenAIRE

Bode, Sven

2003-01-01

Greenhouse gas emission trading has become more and more important in the context of climate change. Recently, a discussion on trading on entity (i.e. company) level has started. Emitters likely to be obliged to participate have argued for an initial allocation of the emission rights free of charge. I analyse the implication of such an allocation based on historical emissions and on benchmarks in multi-period emission trading. Different allocation rules for successive periods are applied, nam...

SVM-Based Spectral Analysis for Heart Rate from Multi-Channel WPPG Sensor Signals.

Science.gov (United States)

Xiong, Jiping; Cai, Lisang; Wang, Fei; He, Xiaowei

2017-03-03

Although wrist-type photoplethysmographic (hereafter referred to as WPPG) sensor signals can measure heart rate quite conveniently, the subjects' hand movements can cause strong motion artifacts, and then the motion artifacts will heavily contaminate WPPG signals. Hence, it is challenging for us to accurately estimate heart rate from WPPG signals during intense physical activities. The WWPG method has attracted more attention thanks to the popularity of wrist-worn wearable devices. In this paper, a mixed approach called Mix-SVM is proposed, it can use multi-channel WPPG sensor signals and simultaneous acceleration signals to measurement heart rate. Firstly, we combine the principle component analysis and adaptive filter to remove a part of the motion artifacts. Due to the strong relativity between motion artifacts and acceleration signals, the further denoising problem is regarded as a sparse signals reconstruction problem. Then, we use a spectrum subtraction method to eliminate motion artifacts effectively. Finally, the spectral peak corresponding to heart rate is sought by an SVM-based spectral analysis method. Through the public PPG database in the 2015 IEEE Signal Processing Cup, we acquire the experimental results, i.e., the average absolute error was 1.01 beat per minute, and the Pearson correlation was 0.9972. These results also confirm that the proposed Mix-SVM approach has potential for multi-channel WPPG-based heart rate estimation in the presence of intense physical exercise.

Determining fast orientation changes of multi-spectral line cameras from the primary images

Science.gov (United States)

Wohlfeil, Jürgen

2012-01-01

Fast orientation changes of airborne and spaceborne line cameras cannot always be avoided. In such cases it is essential to measure them with high accuracy to ensure a good quality of the resulting imagery products. Several approaches exist to support the orientation measurement by using optical information received through the main objective/telescope. In this article an approach is proposed that allows the determination of non-systematic orientation changes between every captured line. It does not require any additional camera hardware or onboard processing capabilities but the payload images and a rough estimate of the camera's trajectory. The approach takes advantage of the typical geometry of multi-spectral line cameras with a set of linear sensor arrays for different spectral bands on the focal plane. First, homologous points are detected within the heavily distorted images of different spectral bands. With their help a connected network of geometrical correspondences can be built up. This network is used to calculate the orientation changes of the camera with the temporal and angular resolution of the camera. The approach was tested with an extensive set of aerial surveys covering a wide range of different conditions and achieved precise and reliable results.

Atomic imaging by x-ray-fluorescence holography and electron-emission holography: A comparative theoretical study

International Nuclear Information System (INIS)

Len, P.M.; Thevuthasan, S.; Fadley, C.S.; Kaduwela, A.P.; Van Hove, M.A.

1994-01-01

We consider from a theoretical viewpoint the direct imaging of atoms at and near the surfaces of solids by both x-ray-fluorescence holography (XFH) and electron-emission holography (EEH). The more ideal nature of x-ray scattering makes XFH images superior to those in single-energy EEH. The overlap of real and twin features for pairs of atoms at ±a can cause their XFH or EEH atomic images to cancel for certain combinations of wave vector and |a|. The relative merits of XFH and EEH for structure studies are considered

Characterization of near-infrared nonmetal atomic emission from an atmospheric helium microwave-induced plasma using a Fourier transform spectrophotometer

International Nuclear Information System (INIS)

Hubert, J.; Van Tra, H.; Chi Tran, K.; Baudais, F.L.

1986-01-01

A new approach for using Fourier transform spectroscopy (FTS) for the detection of atomic emission from an atmospheric helium plasma has been developed and the results obtained are described. Among the different types of plasma source available, the atmospheric pressure microwave helium plasma appears to be an efficient excitation source for the determination of nonmetal species. The more complete microwave plasma emission spectra of Cl, Br, I, S, O, P, C, N, and He in the near-infrared region were obtained and their corrected relative emission intensities are reported. This makes qualitative identification simple, and aids in the quantitative analysis of atomic species. The accuracy of the emission wavelengths obtained with the Fourier transform spectrophotometer was excellent and the resolution provided by the FTS allowed certain adjacent emission lines to be adequate for analytical applications

A Simple LIBS (Laser-Induced Breakdown Spectroscopy) Laboratory Experiment to Introduce Undergraduates to Calibration Functions and Atomic Spectroscopy

Science.gov (United States)

Chinni, Rosemarie C.

2012-01-01

This laboratory experiment introduces students to a different type of atomic spectroscopy: laser-induced breakdown spectroscopy (LIBS). LIBS uses a laser-generated spark to excite the sample; once excited, the elemental emission is spectrally resolved and detected. The students use LIBS to analyze a series of standard synthetic silicate samples…

Impurity line emission due to thermal charge exchange in JET edge plasmas

Energy Technology Data Exchange (ETDEWEB)

Maggi, C F; Horton, L D; Koenig, R; Stamp, M [Commission of the European Communities, Abingdon (United Kingdom). JET Joint Undertaking; Summers, H P [Strathclyde Univ., Glasgow (United Kingdom)

1994-07-01

High n-shell emission from hydrogen-like carbon (C VI, n=8-7) has been routinely observed from the plasma edge of JET. By comparing the measured spectral line intensities with the signals predicted by advanced atomic physics modelling of carbon and hydrogen radiation, integrated with modelling of the divertor and edge plasma, it is concluded that charge transfer from excited state hydrogen donors into fully stripped carbon ions can account for the observed spectral emission, but that the hydrogen distribution and to a lesser extent the carbon distribution away from the strike zone predicted by the transport model are too low. Data presented are those of three upper X-point discharges, where the target material was carbon. 5 refs., 1 fig., 3 tabs.

Determination of Ar metastable atom densities in Ar and Ar/H2 inductively coupled low-temperature plasmas

International Nuclear Information System (INIS)

Fox-Lyon, N; Knoll, A J; Oehrlein, G S; Franek, J; Demidov, V; Koepke, M; Godyak, V

2013-01-01

Ar metastable atoms are important energy carriers and surface interacting species in low-temperature plasmas that are difficult to quantify. Ar metastable atom densities (N Ar,m ) in inductively coupled Ar and Ar/H 2 plasmas were obtained using a model combining electrical probe measurements of electron density (N e ) and temperature (T e ), with analysis of spectrally resolved Ar plasma optical emission based on 3p → 1s optical emission ratios of the 419.8 nm line to the 420.1 nm line. We present the variation of N Ar,m as the Ar pressure and the addition of H 2 to Ar are changed comparatively to recent adsorption spectroscopy measurements. (paper)

A variational multi-scale method with spectral approximation of the sub-scales: Application to the 1D advection-diffusion equations

KAUST Repository

Chacó n Rebollo, Tomá s; Dia, Ben Mansour

2015-01-01

This paper introduces a variational multi-scale method where the sub-grid scales are computed by spectral approximations. It is based upon an extension of the spectral theorem to non necessarily self-adjoint elliptic operators that have an associated base of eigenfunctions which are orthonormal in weighted L2 spaces. This allows to element-wise calculate the sub-grid scales by means of the associated spectral expansion. We propose a feasible VMS-spectral method by truncation of this spectral expansion to a finite number of modes. We apply this general framework to the convection-diffusion equation, by analytically computing the family of eigenfunctions. We perform a convergence and error analysis. We also present some numerical tests that show the stability of the method for an odd number of spectral modes, and an improvement of accuracy in the large resolved scales, due to the adding of the sub-grid spectral scales.

A variational multi-scale method with spectral approximation of the sub-scales: Application to the 1D advection-diffusion equations

KAUST Repository

Chacón Rebollo, Tomás

2015-03-01

This paper introduces a variational multi-scale method where the sub-grid scales are computed by spectral approximations. It is based upon an extension of the spectral theorem to non necessarily self-adjoint elliptic operators that have an associated base of eigenfunctions which are orthonormal in weighted L2 spaces. This allows to element-wise calculate the sub-grid scales by means of the associated spectral expansion. We propose a feasible VMS-spectral method by truncation of this spectral expansion to a finite number of modes. We apply this general framework to the convection-diffusion equation, by analytically computing the family of eigenfunctions. We perform a convergence and error analysis. We also present some numerical tests that show the stability of the method for an odd number of spectral modes, and an improvement of accuracy in the large resolved scales, due to the adding of the sub-grid spectral scales.

Atomic physics

CERN Document Server

Born, Max

1969-01-01

The Nobel Laureate's brilliant exposition of the kinetic theory of gases, elementary particles, the nuclear atom, wave-corpuscles, atomic structure and spectral lines, electron spin and Pauli's principle, quantum statistics, molecular structure and nuclear physics. Over 40 appendices, a bibliography, numerous figures and graphs.

The 1600 Å Emission Bump in Protoplanetary Disks: A Spectral Signature of H2O Dissociation

Science.gov (United States)

France, Kevin; Roueff, Evelyne; Abgrall, Hervé

2017-08-01

The FUV continuum spectrum of many accreting pre-main sequence stars, Classical T Tauri Stars (CTTSs), does not continue smoothly from the well-studied Balmer continuum emission in the NUV, suggesting that additional processes contribute to the short-wavelength emission in these objects. The most notable spectral feature in the FUV continuum of some CTTSs is a broad emission approximately centered at 1600 Å, which has been referred to as the “1600 Å Bump.” The origin of this feature remains unclear. In an effort to better understand the molecular properties of planet-forming disks and the UV spectral properties of accreting protostars, we have assembled archival FUV spectra of 37 disk-hosting systems observed by the Hubble Space Telescope-Cosmic Origins Spectrograph. Clear 1600 Å Bump emission is observed above the smooth, underlying 1100-1800 Å continuum spectrum in 19/37 Classical T Tauri disks in the HST-COS sample, with the detection rate in transition disks (8/8) being much higher than that in primordial or non-transition sources (11/29). We describe a spectral deconvolution analysis to separate the Bump (spanning 1490-1690 Å) from the underlying FUV continuum, finding an average Bump luminosity L(Bump) ≈ 7 × 1029 erg s-1. Parameterizing the Bump with a combination of Gaussian and polynomial components, we find that the 1600 Å Bump is characterized by a peak wavelength λ o = 1598.6 ± 3.3 Å, with FWHM = 35.8 ± 19.1 Å. Contrary to previous studies, we find that this feature is inconsistent with models of H2 excited by electron -impact. We show that this Bump makes up between 5%-50% of the total FUV continuum emission in the 1490-1690 Å band and emits roughly 10%-80% of the total fluorescent H2 luminosity for stars with well-defined Bump features. Energetically, this suggests that the carrier of the 1600 Å Bump emission is powered by Lyα photons. We argue that the most likely mechanism is Lyα-driven dissociation of H2O in the inner disk, r �

Combined frequency modulated atomic force microscopy and scanning tunneling microscopy detection for multi-tip scanning probe microscopy applications

International Nuclear Information System (INIS)

Morawski, Ireneusz; Spiegelberg, Richard; Korte, Stefan; Voigtländer, Bert

2015-01-01

A method which allows scanning tunneling microscopy (STM) tip biasing independent of the sample bias during frequency modulated atomic force microscopy (AFM) operation is presented. The AFM sensor is supplied by an electronic circuit combining both a frequency shift signal and a tunneling current signal by means of an inductive coupling. This solution enables a control of the tip potential independent of the sample potential. Individual tip biasing is specifically important in order to implement multi-tip STM/AFM applications. An extensional quartz sensor (needle sensor) with a conductive tip is applied to record simultaneously topography and conductivity of the sample. The high resonance frequency of the needle sensor (1 MHz) allows scanning of a large area of the surface being investigated in a reasonably short time. A recipe for the amplitude calibration which is based only on the frequency shift signal and does not require the tip being in contact is presented. Additionally, we show spectral measurements of the mechanical vibration noise of the scanning system used in the investigations

Combined frequency modulated atomic force microscopy and scanning tunneling microscopy detection for multi-tip scanning probe microscopy applications

Energy Technology Data Exchange (ETDEWEB)

Morawski, Ireneusz [Peter Grünberg Institut (PGI-3) and JARA-Fundamentals of Future Information Technology, Forschungszentrum Jülich, 52425 Jülich (Germany); Institute of Experimental Physics, University of Wrocław, pl. M. Borna 9, 50-204 Wrocław (Poland); Spiegelberg, Richard; Korte, Stefan; Voigtländer, Bert [Peter Grünberg Institut (PGI-3) and JARA-Fundamentals of Future Information Technology, Forschungszentrum Jülich, 52425 Jülich (Germany)

2015-12-15

A method which allows scanning tunneling microscopy (STM) tip biasing independent of the sample bias during frequency modulated atomic force microscopy (AFM) operation is presented. The AFM sensor is supplied by an electronic circuit combining both a frequency shift signal and a tunneling current signal by means of an inductive coupling. This solution enables a control of the tip potential independent of the sample potential. Individual tip biasing is specifically important in order to implement multi-tip STM/AFM applications. An extensional quartz sensor (needle sensor) with a conductive tip is applied to record simultaneously topography and conductivity of the sample. The high resonance frequency of the needle sensor (1 MHz) allows scanning of a large area of the surface being investigated in a reasonably short time. A recipe for the amplitude calibration which is based only on the frequency shift signal and does not require the tip being in contact is presented. Additionally, we show spectral measurements of the mechanical vibration noise of the scanning system used in the investigations.

Modeling Emission of Heavy Energetic Neutral Atoms from the Heliosphere

International Nuclear Information System (INIS)

Swaczyna, Paweł; Bzowski, Maciej

2017-01-01

Observations of energetic neutral atoms (ENAs) are a fruitful tool for remote diagnosis of the plasma in the heliosphere and its vicinity. So far, instruments detecting ENAs from the heliosphere were configured for observations of hydrogen atoms. Here, we estimate emissions of ENAs of the heavy chemical elements helium, oxygen, nitrogen, and neon. A large portion of the heliospheric ENAs is created in the inner heliosheath from neutralized interstellar pick-up ions (PUIs). We modeled this process and calculated full-sky intensities of ENAs for energies 0.2–130 keV/nuc. We found that the largest fluxes among considered species are expected for helium, smaller for oxygen and nitrogen, and smallest for neon. The obtained intensities are 50–10 6 times smaller than the hydrogen ENA intensities observed by IBEX . The detection of heavy ENAs will be possible if a future ENA detector is equipped with the capability to measure the masses of observed atoms. Because of different reaction cross-sections among the different species, observations of heavy ENAs can allow for a better understanding of global structure of the heliosphere as well as the transport and energization of PUIs in the heliosphere.

Modeling Emission of Heavy Energetic Neutral Atoms from the Heliosphere

Energy Technology Data Exchange (ETDEWEB)

Swaczyna, Paweł; Bzowski, Maciej, E-mail: pswaczyna@cbk.waw.pl [Space Research Centre of the Polish Academy of Sciences (CBK PAN), Bartycka 18A, 00-716 Warsaw (Poland)

2017-09-10

Observations of energetic neutral atoms (ENAs) are a fruitful tool for remote diagnosis of the plasma in the heliosphere and its vicinity. So far, instruments detecting ENAs from the heliosphere were configured for observations of hydrogen atoms. Here, we estimate emissions of ENAs of the heavy chemical elements helium, oxygen, nitrogen, and neon. A large portion of the heliospheric ENAs is created in the inner heliosheath from neutralized interstellar pick-up ions (PUIs). We modeled this process and calculated full-sky intensities of ENAs for energies 0.2–130 keV/nuc. We found that the largest fluxes among considered species are expected for helium, smaller for oxygen and nitrogen, and smallest for neon. The obtained intensities are 50–10{sup 6} times smaller than the hydrogen ENA intensities observed by IBEX . The detection of heavy ENAs will be possible if a future ENA detector is equipped with the capability to measure the masses of observed atoms. Because of different reaction cross-sections among the different species, observations of heavy ENAs can allow for a better understanding of global structure of the heliosphere as well as the transport and energization of PUIs in the heliosphere.

Position Dependent Spontaneous Emission Spectra of a Λ-Type Atomic System Embedded in a Defective Photonic Crystal

International Nuclear Information System (INIS)

Entezar, S. Roshan

2012-01-01

We investigate the position dependent spontaneous emission spectra of a Λ-type three-level atom with one transition coupled to the free vacuum reservoir and the other one coupled to a double-band photonic band gap reservoir with a defect mode in the band gap. It is shown that, for the atom at the defect location, we have a two-peak spectrum with a wide dark line due to the strong coupling between the atom and the defect mode. While, when the atom is far from the defect location (or in the absence of the defect mode), the spectrum has three peaks with two dark lines due to the coupling between the atom and the photonic band gap reservoir with the largest density of states near the band edges. On the other hand, we have a four-peak spectrum for the atom at the space in between. Moreover, the average spontaneous emission spectra of the atoms uniformly embedded in high dielectric or low dielectric regions are described. It is shown that the atoms embedded in high (low) dielectric regions far from the defect location, effectively couple to the modes of the lower (upper) photonic band. However, the atoms embedded in high dielectric or low dielectric regions at the defect location, are coupled mainly to the defect modes. While, the atoms uniformly embedded in high (low) dielectric regions with a normal distance from the defect location, are coupled to both of defect and lower (upper) photonic band modes. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

Total emissivity and spectral emissivity of high-temperature materials; Gesamtemissionsgrad und spektraler Emissionsgrad von Hochtemperaturmaterialien

Energy Technology Data Exchange (ETDEWEB)

Neuer, G.; Pohlmann, P.; Schreiber, E.

1998-05-01

A new emissivity measurement device with inductive sample heating is described. The disc shaped samples can be measured between 800 C and 2000 C in vacuum or in each available gas atmosphere. Two kinds of surface temperature measurement methods are described, one by measuring in a blackbody hole and one by measuring at the surface without additional measures to correct emissivity. Total normal and spectral emissivity at wavelengths between 0,5 {mu}m and 8,3 {mu}m of various high temperature materials like platinum and Pt-Rh-alloys, siliconcarbide and molybdenum disilicide have been measured. From the investigated materials a few have been selected as reference samples for comparative emissivity measurements fullfilling the requirement of stability on air up to 400 C to 1000 C in order to ensure reproducibility of the results at different measurement conditions in air and in vacuum. (orig.) [Deutsch] Der Aufbau einer neuen Messapparatur fuer Emissionsgradmessungen bei Temperaturen zwischen 1000 C und 2000 C wird beschrieben. Die scheibenfoermigen Proben werden induktiv beheizt, und die Messungen koennen entweder in Vakuum oder einer beliebigen Gasatmosphaere durchgefuehrt werden. Es werden zwei verschiedene Verfahren zur Bestimmung der Oberflaechentemperatur bechrieben, wobei entweder in einer oder direkt an der Oberflaeche ohne zusaetzliche Massnahmen zur Emissionsgradkorrektur gemessen wird. An verschiedenen Hochtemperaturwerkstoffen wie Platin und Platin-Rhodium-Legierungen, Siliziumkarbid mit unterschiedlichen Herstellungsarten und Molybdaen-Disilizid wurden der Gesamtemissionsgrad und der spektrale Emissionsgrad bei Wellenlaengen von 0,5 {mu}m bis 8,3 {mu}m senkrecht zur Oberflaeche gemessen. Aus den untersuchten Materialien wurden solche als Referenzmaterialien fuer vergleichende Emissionsgradmessungen ausgewaehlt, die sowohl im Vakuum als auch in Luft und bei Temperaturen von 1400 C bis 1600 C unter verschiedenen Messbedingungen reproduzierbare Ergebnisse

Multi-Configuration Matched Spectral Filter Core, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — OPTRA proposes an open-architecture spectral gas sensor based on compressive sensing concepts employed for both spatial and spectral domains. Our matched spectral...

Collaborative Emission Reduction Model Based on Multi-Objective Optimization for Greenhouse Gases and Air Pollutants.

Science.gov (United States)

Meng, Qing-chun; Rong, Xiao-xia; Zhang, Yi-min; Wan, Xiao-le; Liu, Yuan-yuan; Wang, Yu-zhi

2016-01-01

CO2 emission influences not only global climate change but also international economic and political situations. Thus, reducing the emission of CO2, a major greenhouse gas, has become a major issue in China and around the world as regards preserving the environmental ecology. Energy consumption from coal, oil, and natural gas is primarily responsible for the production of greenhouse gases and air pollutants such as SO2 and NOX, which are the main air pollutants in China. In this study, a mathematical multi-objective optimization method was adopted to analyze the collaborative emission reduction of three kinds of gases on the basis of their common restraints in different ways of energy consumption to develop an economic, clean, and efficient scheme for energy distribution. The first part introduces the background research, the collaborative emission reduction for three kinds of gases, the multi-objective optimization, the main mathematical modeling, and the optimization method. The second part discusses the four mathematical tools utilized in this study, which include the Granger causality test to analyze the causality between air quality and pollutant emission, a function analysis to determine the quantitative relation between energy consumption and pollutant emission, a multi-objective optimization to set up the collaborative optimization model that considers energy consumption, and an optimality condition analysis for the multi-objective optimization model to design the optimal-pole algorithm and obtain an efficient collaborative reduction scheme. In the empirical analysis, the data of pollutant emission and final consumption of energies of Tianjin in 1996-2012 was employed to verify the effectiveness of the model and analyze the efficient solution and the corresponding dominant set. In the last part, several suggestions for collaborative reduction are recommended and the drawn conclusions are stated.

Spatio-spectral analysis of ionization times in high-harmonic generation

Energy Technology Data Exchange (ETDEWEB)

Soifer, Hadas, E-mail: hadas.soifer@weizmann.ac.il [Department of Physics of Complex Systems, Weizmann Institute of Science, Rehovot 76100 (Israel); Dagan, Michal; Shafir, Dror; Bruner, Barry D. [Department of Physics of Complex Systems, Weizmann Institute of Science, Rehovot 76100 (Israel); Ivanov, Misha Yu. [Department of Physics, Imperial College London, South Kensington Campus, SW7 2AZ London (United Kingdom); Max-Born Institute for Nonlinear Optics and Short Pulse Spectroscopy, Max-Born-Strasse 2A, D-12489 Berlin (Germany); Serbinenko, Valeria; Barth, Ingo; Smirnova, Olga [Max-Born Institute for Nonlinear Optics and Short Pulse Spectroscopy, Max-Born-Strasse 2A, D-12489 Berlin (Germany); Dudovich, Nirit [Department of Physics of Complex Systems, Weizmann Institute of Science, Rehovot 76100 (Israel)

2013-03-12

Graphical abstract: A spatio-spectral analysis of the two-color oscillation phase allows us to accurately separate short and long trajectories and reconstruct their ionization times. Highlights: ► We perform a complete spatio-spectral analysis of the high harmonic generation process. ► We analyze the ionization times across the entire spatio-spectral plane of the harmonics. ► We apply this analysis to reconstruct the ionization times of both short and long trajectories. - Abstract: Recollision experiments have been very successful in resolving attosecond scale dynamics. However, such schemes rely on the single atom response, neglecting the macroscopic properties of the interaction and the effects of using multi-cycle laser fields. In this paper we perform a complete spatio-spectral analysis of the high harmonic generation process and resolve the distribution of the subcycle dynamics of the recolliding electron. Specifically, we focus on the measurement of ionization times. Recently, we have demonstrated that the addition of a weak, crossed polarized second harmonic field allows us to resolve the moment of ionization (Shafir, 2012) [1]. In this paper we extend this measurement and perform a complete spatio-spectral analysis. We apply this analysis to reconstruct the ionization times of both short and long trajectories showing good agreement with the quantum path analysis.

Solving Multi-Pollutant Emission Dispatch Problem Using Computational Intelligence Technique

Directory of Open Access Journals (Sweden)

Nur Azzammudin Rahmat

2016-06-01

Full Text Available Economic dispatch is a crucial process conducted by the utilities to correctly determine the satisfying amount of power to be generated and distributed to the consumers. During the process, the utilities also consider pollutant emission as the consequences of fossil-fuel consumption. Fossil-fuel includes petroleum, coal, and natural gas; each has its unique chemical composition of pollutants i.e. sulphur oxides (SOX, nitrogen oxides (NOX and carbon oxides (COX. This paper presents multi-pollutant emission dispatch problem using computational intelligence technique. In this study, a novel emission dispatch technique is formulated to determine the amount of the pollutant level. It utilizes a pre-developed optimization technique termed as differential evolution immunized ant colony optimization (DEIANT for the emission dispatch problem. The optimization results indicated high level of COX level, regardless of any type of fossil fuel consumed.

Multi-flux-transformer MRI detection with an atomic magnetometer.

Science.gov (United States)

Savukov, Igor; Karaulanov, Todor

2014-12-01

Recently, anatomical ultra-low field (ULF) MRI has been demonstrated with an atomic magnetometer (AM). A flux-transformer (FT) has been used for decoupling MRI fields and gradients to avoid their negative effects on AM performance. The field of view (FOV) was limited because of the need to compromise between the size of the FT input coil and MRI sensitivity per voxel. Multi-channel acquisition is a well-known solution to increase FOV without significantly reducing sensitivity. In this paper, we demonstrate twofold FOV increase with the use of three FT input coils. We also show that it is possible to use a single atomic magnetometer and single acquisition channel to acquire three independent MRI signals by applying a frequency-encoding gradient along the direction of the detection array span. The approach can be generalized to more channels and can be critical for imaging applications of non-cryogenic ULF MRI where FOV needs to be large, including head, hand, spine, and whole-body imaging. Copyright © 2014 Elsevier Inc. All rights reserved.

Multi-spectral optical absorption in substrate-free nanowire arrays

Energy Technology Data Exchange (ETDEWEB)

Zhang, Junpeng; Chia, Andrew; Boulanger, Jonathan; LaPierre, Ray, E-mail: lapierr@mcmaster.ca [Department of Engineering Physics, McMaster University, 1280 Main St. West, Hamilton, Ontario L8S 4L7 (Canada); Dhindsa, Navneet; Khodadad, Iman; Saini, Simarjeet [Department of Electrical and Computer Engineering, University of Waterloo, 200 University Ave West, Waterloo, Ontario N2L 3G1 (Canada); Waterloo Institute of Nanotechnology, University of Waterloo, 200 University Ave West, Waterloo, Ontario N2L 3G1 (Canada)

2014-09-22

A method is presented of fabricating gallium arsenide (GaAs) nanowire arrays of controlled diameter and period by reactive ion etching of a GaAs substrate containing an indium gallium arsenide (InGaP) etch stop layer, allowing the precise nanowire length to be controlled. The substrate is subsequently removed by selective etching, using the same InGaP etch stop layer, to create a substrate-free GaAs nanowire array. The optical absorptance of the nanowire array was then directly measured without absorption from a substrate. We directly observe absorptance spectra that can be tuned by the nanowire diameter, as explained with rigorous coupled wave analysis. These results illustrate strong optical absorption suitable for nanowire-based solar cells and multi-spectral absorption for wavelength discriminating photodetectors. The solar-weighted absorptance above the bandgap of GaAs was 94% for a nanowire surface coverage of only 15%.

Principle component analysis and linear discriminant analysis of multi-spectral autofluorescence imaging data for differentiating basal cell carcinoma and healthy skin

Science.gov (United States)

Chernomyrdin, Nikita V.; Zaytsev, Kirill I.; Lesnichaya, Anastasiya D.; Kudrin, Konstantin G.; Cherkasova, Olga P.; Kurlov, Vladimir N.; Shikunova, Irina A.; Perchik, Alexei V.; Yurchenko, Stanislav O.; Reshetov, Igor V.

2016-09-01

In present paper, an ability to differentiate basal cell carcinoma (BCC) and healthy skin by combining multi-spectral autofluorescence imaging, principle component analysis (PCA), and linear discriminant analysis (LDA) has been demonstrated. For this purpose, the experimental setup, which includes excitation and detection branches, has been assembled. The excitation branch utilizes a mercury arc lamp equipped with a 365-nm narrow-linewidth excitation filter, a beam homogenizer, and a mechanical chopper. The detection branch employs a set of bandpass filters with the central wavelength of spectral transparency of λ = 400, 450, 500, and 550 nm, and a digital camera. The setup has been used to study three samples of freshly excised BCC. PCA and LDA have been implemented to analyze the data of multi-spectral fluorescence imaging. Observed results of this pilot study highlight the advantages of proposed imaging technique for skin cancer diagnosis.

Multi-objective optimisation of wastewater treatment plant control to reduce greenhouse gas emissions.

Science.gov (United States)

Sweetapple, Christine; Fu, Guangtao; Butler, David

2014-05-15

This study investigates the potential of control strategy optimisation for the reduction of operational greenhouse gas emissions from wastewater treatment in a cost-effective manner, and demonstrates that significant improvements can be realised. A multi-objective evolutionary algorithm, NSGA-II, is used to derive sets of Pareto optimal operational and control parameter values for an activated sludge wastewater treatment plant, with objectives including minimisation of greenhouse gas emissions, operational costs and effluent pollutant concentrations, subject to legislative compliance. Different problem formulations are explored, to identify the most effective approach to emissions reduction, and the sets of optimal solutions enable identification of trade-offs between conflicting objectives. It is found that multi-objective optimisation can facilitate a significant reduction in greenhouse gas emissions without the need for plant redesign or modification of the control strategy layout, but there are trade-offs to consider: most importantly, if operational costs are not to be increased, reduction of greenhouse gas emissions is likely to incur an increase in effluent ammonia and total nitrogen concentrations. Design of control strategies for a high effluent quality and low costs alone is likely to result in an inadvertent increase in greenhouse gas emissions, so it is of key importance that effects on emissions are considered in control strategy development and optimisation. Copyright © 2014 Elsevier Ltd. All rights reserved.

Study of the strongly ionized medium in active galactic n ('Warm Absorber'): multi-wavelength modelling and plasma diagnostics in the X-ray spectral range

International Nuclear Information System (INIS)

Porquet, Delphine

1999-01-01

The so-called 'Warm Absorber' medium is observed in the central region of Active Galactic Nuclei and particularly in Seyfert l galaxies. lt is mainly characterized by O(VII) and O(VIII) absorption edges detected in the soft X-rays. Its study (modelization and observation) is an important key tool to understand Active Galactic Nuclei. The work presented here consists in modelling the Warm Absorber, and in developing X-ray spectroscopy diagnostics to constrain the physical parameters of any hot medium such as the Warm Absorber. The physical parameters of the Warm Absorber (density, temperature, ionization processes..) are difficult to determine only on the basis of present X-ray data. In particular, the value of the density cannot be derived only from the modelling of the resonance lines and of the soft X-ray absorption edges since there are almost insensitive to the density in the range of values expected for the Warm Absorber. lt is why we have developed diagnostic methods based on a multi-wavelength approach. The modelling is made with two complementary computational codes: PEGAS, and IRIS which takes into account the most accurate atomic data. With these two codes, we have modelled several types of plasma ionisation processes (photoionized plasmas and/or collisional). Results for the Warm Absorber were compared to multi-wavelength observations (mainly the optical iron coronal lines [Fe X] 6375 Angstroms, [Fe XI] 7892 Angstroms, and [Fe XIV] 5303 Angstroms). The proposed method has allowed to show that the Warm Absorber could be responsible of the emission of these lines totally or partially. All models of the Warm Absorber producing coronal line equivalent widths larger than observed were ruled out. This strongly constrains the physical parameters of the Warm Absorber, and particularly its density (n H ≥10 10 cm -3 ). The new generation of X-ray satellites (Chandra/AXAF, XMM...) will produce spectra at high spectral resolution and high sensitivity

Study of inter sub-shell and inter shell electron correlations in 4d open-shell heavy atomic ions

International Nuclear Information System (INIS)

Koike, Fumihiro

2009-01-01

The effect of correlations between 4p, 4d, and 4f has been studied extensively. The characteristic spectral structures of 4p - 4d and 4d - 4f optical transitions, due to the unique structures of N = 4 open sub-shells in heavy atomic ions, have been studied theoretically. To gain an insight of this effect, a series of careful MCDF calculations for 4d q (q = 0 to 10) atomic ions with atomic numbers Z = 48 to 56 has been carried out. The difference of orbital energy differences between 4p and 4d orbitals and 4d and 4f orbitals coincidently falls within the range of a few % for almost all the atomic ions investigated. The 4p 6 4d4f and 4p 5 4d 3 configurations may mix strongly, and the optical 4p - 4d and 4d - 4f transitions may take place coherently, providing us with quite a peculiar EUV emission spectrum. The effect of spectral narrowing and shift is expected to be quite common to the atomic specieds with the atomic numbers in the range Z = 48 to 56.

In situ calibration of inductively coupled plasma-atomic emission and mass spectroscopy

Science.gov (United States)

Braymen, Steven D.

1996-06-11

A method and apparatus for in situ addition calibration of an inductively coupled plasma atomic emission spectrometer or mass spectrometer using a precision gas metering valve to introduce a volatile calibration gas of an element of interest directly into an aerosol particle stream. The present situ calibration technique is suitable for various remote, on-site sampling systems such as laser ablation or nebulization.

A NEW MULTI-SPECTRAL THRESHOLD NORMALIZED DIFFERENCE WATER INDEX (MST-NDWI WATER EXTRACTION METHOD – A CASE STUDY IN YANHE WATERSHED

Directory of Open Access Journals (Sweden)

Y. Zhou

2018-05-01

Full Text Available Accurate remote sensing water extraction is one of the primary tasks of watershed ecological environment study. Since the Yanhe water system has typical characteristics of a small water volume and narrow river channel, which leads to the difficulty for conventional water extraction methods such as Normalized Difference Water Index (NDWI. A new Multi-Spectral Threshold segmentation of the NDWI (MST-NDWI water extraction method is proposed to achieve the accurate water extraction in Yanhe watershed. In the MST-NDWI method, the spectral characteristics of water bodies and typical backgrounds on the Landsat/TM images have been evaluated in Yanhe watershed. The multi-spectral thresholds (TM1, TM4, TM5 based on maximum-likelihood have been utilized before NDWI water extraction to realize segmentation for a division of built-up lands and small linear rivers. With the proposed method, a water map is extracted from the Landsat/TM images in 2010 in China. An accuracy assessment is conducted to compare the proposed method with the conventional water indexes such as NDWI, Modified NDWI (MNDWI, Enhanced Water Index (EWI, and Automated Water Extraction Index (AWEI. The result shows that the MST-NDWI method generates better water extraction accuracy in Yanhe watershed and can effectively diminish the confusing background objects compared to the conventional water indexes. The MST-NDWI method integrates NDWI and Multi-Spectral Threshold segmentation algorithms, with richer valuable information and remarkable results in accurate water extraction in Yanhe watershed.

Generation of single attosecond pulse within one atomic unit by using multi-cycle inhomogeneous polarization gating technology in bowtie-shaped nanostructure

Science.gov (United States)

Feng, Liqiang; Liu, Hang

2018-04-01

The generations of high-order harmonic spectra and single attosecond pulses (SAPs) driven by the multi-cycle inhomogeneous polarization gating (PG) technology in the bowtie-shaped nanostructure have been theoretically investigated. It is found that by setting the bowtie-shaped nanostructure along the driven laser polarization direction, not only the extension of the harmonic cutoff can be achieved, caused by the surface plasmon polaritons, but also the modulations of the harmonics can be decreased, caused by the PG technology and the inhomogeneous effect. As a result, the contribution of the harmonic plateau is only from one harmonic emission peak with the dominant short quantum path. Further, by properly adding a half-cycle pulse into the driven laser field, the harmonic emission process can be precisely controlled in the half-cycle duration and a supercontinuum with the bandwidth of 263 eV can be obtained. Finally, by directly superposing the harmonics from this supercontinuum, a SAP with the full width at half maximum of 23 as can be obtained, which is shorter than one atomic unit.

Economic and greenhouse gas emission analysis of bioenergy production using multi-product crops-case studies for the Netherlands and Poland

International Nuclear Information System (INIS)

Dornburg, V.; Termeer, G.; Faaij, A.P.C.

2005-01-01

In the face of climate change that may result from greenhouse gas (GHG) emissions, the scarcity of agricultural land and limited competitiveness of biomass energy on the market, it is desirable to increase the performance of bioenergy systems. Multi-product crops, i.e. using a crop partially for energy and partially for material purposes can possibly create additional incomes as well as additional GHG emission reductions. In this study, the performance of several multi-product crop systems is compared to energy crop systems, focused on the costs of primary biomass fuel costs and GHG emission reductions per hectare of biomass production. The sensitivity of the results is studied by means of a Monte-Carlo analysis. The multi-product crops studied are wheat, hemp and poplar in the Netherlands and Poland. GHG emission reductions of these multi-product crop systems are found to be between 0.2 and 2.4 Mg CO 2eq /(ha yr) in Poland and 0.9 and 7.8 Mg CO 2eq /(ha yr) in the Netherlands, while primary biomass fuel costs range from -4.1 to -1.7 EURO /GJ in the Netherlands and from 0.1 to 9.8 EURO /GJ in Poland. Results show that the economic attractiveness of multi-product crops depends strongly on material market prices, crop production costs and crop yields. Net annual GHG emission reductions per hectare are influenced strongly by the specific GHG emission reduction of material use, reference energy systems and GHG emissions of crop production. Multi-product use of crops can significantly decrease primary biomass fuel costs. However, this does not apply in general, but depends on the kind of crops and material uses. For the examples analysed here, net annual GHG emission reductions per hectare are not lowered by multi-product use of crops. Consequently, multi-product crops are not for granted an option to increase the performance of bioenergy systems. Further research on the feasibility of large-scale multi-product crop systems and their impact on land and material markets

Low-frequency-field-induced spontaneous-emission interference in a two-level atom placed in an anisotropic photonic crystal

International Nuclear Information System (INIS)

Li Gaoxiang; Evers, Joerg; Keitel, Christoph H

2005-01-01

We investigate the spontaneous-emission properties of a two-level atom embedded in a three-dimensional anisotropic photonic crystal. In addition to the modified density of states, the atom is driven by a coherent intense low-frequency field (LFF), which creates additional multiphoton decay channels with the exchange of two low-frequency photons and one spontaneous photon during an atomic transition. Due to the low frequency of the applied field, the various transition pathways may interfere with each other and thus give rise to a modified system dynamics. We find that even if all the atomic (bare and induced) transition frequencies are in the conducting band of the photonic crystal, there still may exist a photon-atom bound state in coexistence with propagating modes. The system also allows us to generate narrow lines in the spontaneous-emission spectrum. This spectrum is a function of the distance of the observer from the atom due to the band gap in the photonic crystal. The system properties depend on three characteristic frequencies, which are influenced by quantum interference effects. Thus these results can be attributed to a combination of interference and band-gap effects

Pulse Shaping for High Capacity Impulse Radio Ultra-Wideband Wireless Links Under the Russian Spectral Emission Mask

DEFF Research Database (Denmark)

Grakhova, Elizaveta P.; Rommel, Simon; Jurado-Navas, Antonio

2016-01-01

Two pulse shapes for IR-UWB transmission under the Russian spectral emission mask are proposed and their potential experimentally demonstrated. Pulses based on the hyperbolic secant square function and the frequency B-spline wavelet are shown to enable transmission of 1.25 Gbit/s signals, reaching...

SVM-Based Spectral Analysis for Heart Rate from Multi-Channel WPPG Sensor Signals

Directory of Open Access Journals (Sweden)

Jiping Xiong

2017-03-01

Full Text Available Although wrist-type photoplethysmographic (hereafter referred to as WPPG sensor signals can measure heart rate quite conveniently, the subjects’ hand movements can cause strong motion artifacts, and then the motion artifacts will heavily contaminate WPPG signals. Hence, it is challenging for us to accurately estimate heart rate from WPPG signals during intense physical activities. The WWPG method has attracted more attention thanks to the popularity of wrist-worn wearable devices. In this paper, a mixed approach called Mix-SVM is proposed, it can use multi-channel WPPG sensor signals and simultaneous acceleration signals to measurement heart rate. Firstly, we combine the principle component analysis and adaptive filter to remove a part of the motion artifacts. Due to the strong relativity between motion artifacts and acceleration signals, the further denoising problem is regarded as a sparse signals reconstruction problem. Then, we use a spectrum subtraction method to eliminate motion artifacts effectively. Finally, the spectral peak corresponding to heart rate is sought by an SVM-based spectral analysis method. Through the public PPG database in the 2015 IEEE Signal Processing Cup, we acquire the experimental results, i.e., the average absolute error was 1.01 beat per minute, and the Pearson correlation was 0.9972. These results also confirm that the proposed Mix-SVM approach has potential for multi-channel WPPG-based heart rate estimation in the presence of intense physical exercise.

Denoising multicriterion iterative reconstruction in emission spectral tomography

Science.gov (United States)

Wan, Xiong; Yin, Aihan

2007-03-01

In the study of optical testing, the computed tomogaphy technique has been widely adopted to reconstruct three-dimensional distributions of physical parameters of various kinds of fluid fields, such as flame, plasma, etc. In most cases, projection data are often stained by noise due to environmental disturbance, instrumental inaccuracy, and other random interruptions. To improve the reconstruction performance in noisy cases, an algorithm that combines a self-adaptive prefiltering denoising approach (SPDA) with a multicriterion iterative reconstruction (MCIR) is proposed and studied. First, the level of noise is approximately estimated with a frequency domain statistical method. Then the cutoff frequency of a Butterworth low-pass filter was established based on the evaluated noise energy. After the SPDA processing, the MCIR algorithm was adopted for limited-view optical computed tomography reconstruction. Simulated reconstruction of two test phantoms and a flame emission spectral tomography experiment were employed to evaluate the performance of SPDA-MCIR in noisy cases. Comparison with some traditional methods and experiment results showed that the SPDA-MCIR combination had obvious improvement in the case of noisy data reconstructions.

Analysis of bauxite by inductively coupled plasma-atomic emission spectroscopy

Science.gov (United States)

Barnes, Ramon M.; Mahanti, Himansu S.

Methods are described for the analysis of bauxite by inductively coupled plasma (ICP) emission spectroscopy. Bauxite samples were dissolved either in HCl, HNO 3, and HF at 160°C in all-PTFE bomb or fused with NaOH. Spectral lines were selected after examination of experimental wavelength scans at each potential analyte wavelength. Limits of detection, background equivalent concentration, and analytical figures of merit were established. The accuracy of the method was confirmed by determining 17 elements in NBS-SRM bauxite samples. Silicon in HF solutions was analyzed using a modified ICP torch with a graphite injector tube, an inert nebulizer using PTFE capillary tubes, and a PTFE spray chamber.

A linear model to predict with a multi-spectral radiometer the amount of nitrogen in winter wheat

NARCIS (Netherlands)

Reyniers, M.; Walvoort, D.J.J.; Baardemaaker, De J.

2006-01-01

The objective was to develop an optimal vegetation index (VIopt) to predict with a multi-spectral radiometer nitrogen in wheat crop (kg[N] ha-1). Optimality means that nitrogen in the crop can be measured accurately in the field during the growing season. It also means that the measurements are

Multi-stage En/decoders integrated in low loss Si3N4-SiO2 for incoherent spectral amplitude OCDMA on PON

NARCIS (Netherlands)

Huiszoon, B.; Leinse, Arne; Geuzebroek, D.H.; Augustin, L.M.; Klein, E.J.; de Waardt, H.; Khoe, G.D.; Koonen, A.M.J.; Emplit, Ph.; Delqué, M.; Gorza, S.-P.; Kockaert, P.; Leijtens, X

2007-01-01

In this paper, we show and analyze, for the first time, the static performance of integrated multi-stage cascade and tree spectral amplitude OCDMA en/decoders (E/Ds) which are fabricated in the low loss Si3N4–SiO2 material system. Combined with incoherent broad spectral sources these E/Ds enable

Spectral response of multi-element silicon detectors

Energy Technology Data Exchange (ETDEWEB)

Ludewigt, B.A.; Rossington, C.S.; Chapman, K. [Univ. of California, Berkeley, CA (United States)

1997-04-01

Multi-element silicon strip detectors, in conjunction with integrated circuit pulse-processing electronics, offer an attractive alternative to conventional lithium-drifted silicon Si(Li) and high purity germanium detectors (HPGe) for high count rate, low noise synchrotron x-ray fluorescence applications. One of the major differences between the segmented Si detectors and the commercially available single-element Si(Li) or HPGe detectors is that hundreds of elements can be fabricated on a single Si substrate using standard silicon processing technologies. The segmentation of the detector substrate into many small elements results in very low noise performance at or near, room temperature, and the count rate of the detector is increased many-fold due to the multiplication in the total number of detectors. Traditionally, a single channel of detector with electronics can handle {approximately}100 kHz count rates while maintaining good energy resolution; the segmented detectors can operate at greater than MHz count rates merely due to the multiplication in the number of channels. One of the most critical aspects in the development of the segmented detectors is characterizing the charge sharing and charge loss that occur between the individual detector strips, and determining how these affect the spectral response of the detectors.

Observation of Switchable Photoresponse of a Monolayer WSe 2 –MoS 2 Lateral Heterostructure via Photocurrent Spectral Atomic Force Microscopic Imaging

KAUST Repository

Son, Youngwoo; Li, Ming-yang; Cheng, Chia-Chin; Wei, Kung-Hwa; Liu, Pingwei; Wang, Qing Hua; Li, Lain-Jong; Strano, Michael S.

2016-01-01

spectral atomic force microscopy to image the current and photocurrent generated between a biased PtIr tip and a monolayer WSe2-MoS2 lateral heterostructure. Current measurements in the dark in both forward and reverse bias reveal an opposite characteristic

Atomic structure calculations and identification of EUV and SXR spectral lines in Sr XXX

Science.gov (United States)

Goyal, Arun; Khatri, Indu; Aggarwal, Sunny; Singh, A. K.; Mohan, Man

2015-08-01

We report an extensive theoretical study of atomic data for Sr XXX in a wide range with L-shell electron excitations to the M-shell. We have calculated energy levels, wave-function compositions and lifetimes for lowest 113 fine structure levels and wavelengths of an extreme Ultraviolet (EUV) and soft X-ray (SXR) transitions. We have employed multi-configuration Dirac Fock method (MCDF) approach within the framework of Dirac-Coulomb Hamiltonian including quantum electrodynamics (QED) and Breit corrections. We have also presented the radiative data for electric and magnetic dipole (E1, M1) and quadrupole (E2, M2) transitions from the ground state. We have made comparisons with available energy levels compiled by NIST and achieve good agreement. But due to inadequate data in the literature, analogous relativistic distorted wave calculations have also been performed using flexible atomic code (FAC) to assess the reliability and accuracy of our results. Additionally, we have provided new atomic data for Sr XXX which is not published elsewhere in the literature and we believe that our results may be beneficial in fusion plasma research and astrophysical investigations and applications.

Dynamic Energy Consumption and Emission Modelling of Container Terminal based on Multi Agents

Directory of Open Access Journals (Sweden)

Hou Jue

2017-01-01

Full Text Available Environmental protection and energy saving pressure press the increasing attention of container terminal operators. In order to comply with the more and more strict environmental regulation, reducing energy consumption and air pollution emissions, meanwhile, optimizing the operation efficiency, which, is an urgent problem to container terminal operator of China. This paper based on the characteristic of Container Terminal Operation System (CTOS, which includes several sections of container product processes, consist of berth allocation problem, truck dispatching problem, yard allocation problem and auxiliary process. Dynamic energy consumption and emissions characteristic of each equipment and process is modelled, this paper presents the architecture of CTOS based on the multi agent system with early-warning model, which is based on multi-class support vector machines (SVM. A simulation on container terminal is built on the JADE platform to support the decision-making of container terminal, which can reduce energy consumption and air pollution emissions, allows the container terminal operator to be more flexible in their decision to meet the Emission Control Area regulation and Green Port Plan of China.

Charging induced emission of neutral atoms from NaCl nanocube corners

International Nuclear Information System (INIS)

Ceresoli, Davide; Zykova-Timan, Tatyana; Tosatti, Erio

2008-01-01

Detachment of neutral cations/anions from solid alkali halides can in principle be provoked by donating/subtracting electrons to the surface of alkali halide crystals, but generally constitutes a very endothermic process. However, the amount of energy required for emission is smaller for atoms located in less favorable positions, such as surface steps and kinks. For a corner ion in an alkali halide cube the binding is the weakest, so it should be easier to remove that atom, once it is neutralized. We carried out first principles density functional calculations and simulations of neutral and charged NaCl nanocubes, to establish the energetics of extraction of neutralized corner ions. Following hole donation (electron removal) we find that detachment of neutral Cl corner atoms will require a limited energy of about 0.8 eV. Conversely, following the donation of an excess electron to the cube, a neutral Na atom is extractable from the corner at the lower cost of about 0.6 eV. Since the cube electron affinity level (close to that a NaCl(100) surface state, which we also determine) is estimated to lie about 1.8 eV below vacuum, the overall energy balance upon donation to the nanocube of a zero-energy electron from vacuum will be exothermic. The atomic and electronic structure of the NaCl(100) surface, and of the nanocube Na and Cl corner vacancies are obtained and analyzed as a byproduct

Multi-spectral quantitative phase imaging based on filtration of light via ultrasonic wave

Science.gov (United States)

Machikhin, A. S.; Polschikova, O. V.; Ramazanova, A. G.; Pozhar, V. E.

2017-07-01

A new digital holographic microscopy scheme for multi-spectral quantitative phase imaging is proposed and implemented. It is based on acousto-optic filtration of wide-band low-coherence light at the entrance of a Mach-Zehnder interferometer, recording and digital processing of interferograms. The key requirements for the acousto-optic filter are discussed. The effectiveness of the technique is demonstrated by calculating the phase maps of human red blood cells at multiple wavelengths in the range 770-810 nm. The scheme can be used for the measurement of dispersion of thin films and biological samples.

Role of sectoral and multi-pollutant emission control strategies in improving atmospheric visibility in the Yangtze River Delta, China

International Nuclear Information System (INIS)

Huang, Kan; Fu, Joshua S.; Gao, Yang; Dong, Xinyi; Zhuang, Guoshun; Lin, Yanfen

2014-01-01

The Community Multi-scale Air Quality modeling system is used to investigate the response of atmospheric visibility to the emission reduction from different sectors (i.e. industries, traffic and power plants) in the Yangtze River Delta, China. Visibility improvement from exclusive reduction of NO x or VOC emission was most inefficient. Sulfate and organic aerosol would rebound if NO x emission was exclusively reduced from any emission sector. The most efficient way to improve the atmospheric visibility was proven to be the multi-pollutant control strategies. Simultaneous emission reductions (20–50%) on NO x , VOC and PM from the industrial and mobile sectors could result in 0.3–1.0 km visibility improvement. And the emission controls on both NO x (85%) and SO 2 (90%) from power plants gained the largest visibility improvement of up to 4.0 km among all the scenarios. The seasonal visibility improvement subject to emission controls was higher in summer while lower in the other seasons. -- Highlights: • Atmospheric visibility in the Yangtze River Delta is modeled and evaluated. • Responses of visibility changes to various emission reduction scenarios are compared. • Sulfate aerosol will increase if only NO x emission is reduced. • The multi-pollutant control strategy is most efficient for improving visibility. -- Responses of visibility changes to various emission reduction scenarios are compared. The multi-pollutant control strategy is most efficient for improving visibility in YRD, China

Data correlation in on-line solid-phase extraction-gas chromatography-atomic emission/mass spectrometric detection of unknown microcontaminants

NARCIS (Netherlands)

Hankemeier, Th.; Rozenbrand, J.; Abhadur, M.; Vreuls, J.J.; Brinkman, U.A.Th.

1998-01-01

A procedure is described for the (non-target) screening of hetero-atom-containing compounds in tap and waste water by correlating data obtained by gas chromatography (GC) using atomic emission (AED) and mass selective (MS) detection. Solid-phase extraction (SPE) was coupled on-line to both GC

Theory of X-ray absorption and emission spectra

International Nuclear Information System (INIS)

Mukoyama, Takeshi

2004-01-01

Theoretical studies on X-ray absorption and emission spectroscopy are discussed. Simple expressions for X-ray emission rate and X-ray absorption cross section are presented in the dipole approximation. Various atomic models to obtain realistic wave functions and theoretical calculations for X-ray absorption cross sections and X-ray emission rates are described. In the case of molecules and solids, molecular orbital methods for electronic structures and molecular wave functions are discussed. The emphasis is on the procedures to obtain the excited-state and continuum wave functions for molecules and to calculate the multi-center dipole matrix elements. The examples of the calculated X-ray absorption and emission spectra are shown and compared with the experimental results

Spectral shape of one-photon luminescence from single gold nanorods

Directory of Open Access Journals (Sweden)

Te Wen

2017-12-01

Full Text Available Light emission from gold nanoparticles was investigated with ultra-narrow-band notch filters to obtain the complete spectral shape. The anti-Stokes emission band was observed at all excitation wavelengths. The spectral shape of the anti-Stokes emission could be well fitted by a Fermi–Dirac-like line shape, while the spectral profile of the Stokes emission could be fitted by a Lorentzian line shape. The electron distribution and local surface plasmon resonance jointly determined the spectral shape. Additionally, we found that the anti-Stokes emission intensity increased more rapidly compared with that of the Stokes emission as illumination power was increased. This phenomenon can be understood from the temperature dependence of the electron distribution owing to photothermal effects.

Analysis of a single-atom dipole trap

International Nuclear Information System (INIS)

Weber, Markus; Volz, Juergen; Saucke, Karen; Kurtsiefer, Christian; Weinfurter, Harald

2006-01-01

We describe a simple experimental technique which allows us to store a single 87 Rb atom in an optical dipole trap. Due to light-induced two-body collisions during the loading stage of the trap the maximum number of captured atoms is locked to one. This collisional blockade effect is confirmed by the observation of photon antibunching in the detected fluorescence light. The spectral properties of single photons emitted by the atom were studied with a narrow-band scanning cavity. We find that the atomic fluorescence spectrum is dominated by the spectral width of the exciting laser light field. In addition we observe a spectral broadening of the atomic fluorescence light due to the Doppler effect. This allows us to determine the mean kinetic energy of the trapped atom corresponding to a temperature of 105 μK. This simple single-atom trap is the key element for the generation of atom-photon entanglement required for future applications in quantum communication and a first loophole-free test of Bell's inequality

Atomic emission lines in the near ultraviolet; hydrogen through krypton, section 2

Science.gov (United States)

Kelly, R. L.

1979-01-01

A compilation of spectra from the first 36 elements was prepared from published literature available through October 1977. In most cases, only those lines which were actually observed in emission or absorption are listed. The wavelengths included range from 2000 Angstroms to 3200 Angstroms with some additional lines up to 3500 Angstroms. Only lines of stripped atoms are reported; no molecular bands are included.

Atomic emission lines in the near ultraviolet; hydrogen through krypton, section 1

Science.gov (United States)

Kelly, R. L.

1979-01-01

A compilation of spectra from the first 36 elements was prepared from published literature available through October 1977. In most cases, only those lines which were actually observed in emission or absorption are listed. The wavelengths included range from 2000 Angstroms to 3200 Angstroms with some additional lines up to 3500 Angstroms. Only lines of stripped atoms are reported; no molecular bands are included.

Direct atomic-emission determination of tungsten in molybdenum oxide in dc arc

International Nuclear Information System (INIS)

Zolotareva, N.I.; Grazhulene, S.S.

2007-01-01

A method of direct atomic-emission determination of tungsten impurity in molybdenum trioxide of high purity in dc arc is presented. Chemically active additives of elementary sulfur and gallium oxide are used to optimize W evaporation rate and residence time in the arc plasma. The procedure is easy to use and provides the limit of W determination at a level of 2x10 -4 wt. % [ru

Multiparameter-dependent spontaneous emission in PbSe quantum dot-doped liquid-core multi-mode fiber

International Nuclear Information System (INIS)

Zhang, Lei; Zhang, Yu; Wu, Hua; Zhang, Tieqiang; Gu, Pengfei; Chu, Hairong; Cui, Tian; Wang, Yiding; Zhang, Hanzhuang; Zhao, Jun; Yu, William W.

2013-01-01

A theoretical model was established in this paper to analyze the properties of 3.50 and 4.39 nm PbSe quantum dot-doped liquid-core multi-mode fiber. This model was applicable to both single- and multi-mode fiber. The three-level system-based light-propagation equations and rate equations were used to calculate the guided spontaneous emission spectra. Considering the multi-mode in the fiber, the normalized intensity distribution of transversal model was improved and simplified. The detailed calculating results were thus obtained and explained using the above-mentioned model. The redshift of the peak position and the evolution of the emission power were observed and analyzed considering the influence of the fiber length, fiber diameter, doping concentration, and the pump power. The redshift increased with the increases of fiber length, fiber diameter, and doping concentration. The optimal fiber length, fiber diameter, and doping concentration were analyzed and confirmed, and the related spontaneous emission power was obtained. Besides, the normalized emission intensity increased with the increase of pump power in a nearly linear way. The calculating results fitted well to the experimental data

Influence of multi-hit capability on quantitative measurement of NiPtSi thin film with laser-assisted atom probe tomography

International Nuclear Information System (INIS)

Kinno, T.; Akutsu, H.; Tomita, M.; Kawanaka, S.; Sonehara, T.; Hokazono, A.; Renaud, L.; Martin, I.; Benbalagh, R.; Sallé, B.; Takeno, S.

2012-01-01

Highlights: ► Laser-assisted atom probe tomography was applied to NiPtSi films on Si substrates. ► Comparison of depth profiles of single-hit events and those of multi-hit events. ► ∼80% of Pt atoms were detected in multi-hit events. ► Multiple-ion detection is important for Laser-assisted atom probe tomography. - Abstract: Laser-assisted atom probe tomography (LA-APT) was applied to NiPtSi (0, 30, and 50% Pt contents) thin films on Si substrates. Consistent results with those of high-resolution Rutherford backscattering spectrometry (HR-RBS) were obtained. Based on the obtained data sets, the composition profiles from only the signals of single-hit events, meaning detection of one ion by one laser pulse, were compiled. The profiles from only the signals of multi-hit events, meaning detection of multiple ions by one laser pulse, were also compiled. There were large discrepancies with respect to Ni and Pt concentrations among the compiled profiles and the original profiles including the signals of both types of detection events. Additionally, the profiles compiled from single-hit events showed that Si concentration in NiPtSi layer became smaller toward the surface, differing from the original profiles and the multi-hit profiles. These results suggest that capability of simultaneous multiple-ion detection is important for appropriate LA-APT analyses.

The 1600 Å Emission Bump in Protoplanetary Disks: A Spectral Signature of H{sub 2}O Dissociation

Energy Technology Data Exchange (ETDEWEB)

France, Kevin [Laboratory for Atmospheric and Space Physics, University of Colorado, 600 UCB, Boulder, CO 80309 (United States); Roueff, Evelyne; Abgrall, Hervé, E-mail: kevin.france@colorado.edu [LERMA, Observatoire de Paris, PSL Research University, CNRS, Sorbonne Universités, UPMC Univ. Paris 06, F-92190, Meudon (France)

2017-08-01

The FUV continuum spectrum of many accreting pre-main sequence stars, Classical T Tauri Stars (CTTSs), does not continue smoothly from the well-studied Balmer continuum emission in the NUV, suggesting that additional processes contribute to the short-wavelength emission in these objects. The most notable spectral feature in the FUV continuum of some CTTSs is a broad emission approximately centered at 1600 Å, which has been referred to as the “1600 Å Bump.” The origin of this feature remains unclear. In an effort to better understand the molecular properties of planet-forming disks and the UV spectral properties of accreting protostars, we have assembled archival FUV spectra of 37 disk-hosting systems observed by the Hubble Space Telescope -Cosmic Origins Spectrograph. Clear 1600 Å Bump emission is observed above the smooth, underlying 1100–1800 Å continuum spectrum in 19/37 Classical T Tauri disks in the HST -COS sample, with the detection rate in transition disks (8/8) being much higher than that in primordial or non-transition sources (11/29). We describe a spectral deconvolution analysis to separate the Bump (spanning 1490–1690 Å) from the underlying FUV continuum, finding an average Bump luminosity L (Bump) ≈ 7 × 10{sup 29} erg s{sup −1}. Parameterizing the Bump with a combination of Gaussian and polynomial components, we find that the 1600 Å Bump is characterized by a peak wavelength λ {sub o} = 1598.6 ± 3.3 Å, with FWHM = 35.8 ± 19.1 Å. Contrary to previous studies, we find that this feature is inconsistent with models of H{sub 2} excited by electron -impact. We show that this Bump makes up between 5%–50% of the total FUV continuum emission in the 1490–1690 Å band and emits roughly 10%–80% of the total fluorescent H{sub 2} luminosity for stars with well-defined Bump features. Energetically, this suggests that the carrier of the 1600 Å Bump emission is powered by Ly α photons. We argue that the most likely mechanism

Angle and Spin Resolved Auger Emission Theory and Applications to Atoms and Molecules

CERN Document Server

Lohmann, Bernd

2009-01-01

The Auger effect must be interpreted as the radiationless counterpart of photoionization and is usually described within a two-step model. Angle and spin resolved Auger emission physics deals with the theoretical and numerical description, analysis and interpretation of such types of experiments on free atoms and molecules. This monograph derives the general theory applying the density matrix formalism and, in terms of irreducible tensorial sets, so called state multipoles and order parameters, for parameterizing the atomic and molecular systems, respectively. Propensity rules and non-linear dependencies between the angular distribution and spin polarization parameters are included in the discussion. The numerical approaches utilizing relativistic distorted wave (RDWA), multiconfigurational Dirac-Fock (MCDF), and Greens operator methods are described. These methods are discussed and applied to theoretical predictions, numerical results and experimental data for a variety of atomic systems, especially the rare...

Theoretical modeling and analysis of the emission spectra of a ChemCam standard: Basalt BIR-1A

Energy Technology Data Exchange (ETDEWEB)

Colgan, J. [Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Judge, E.J. [Chemical Diagnostics and Engineering, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Johns, H.M.; Kilcrease, D.P. [Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Barefield, J.E. [Chemical Diagnostics and Engineering, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); McInroy, R. [Physical Chemistry and Applied Spectroscopy, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Hakel, P. [Computational Physics Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Wiens, R.C. [Space and Remote Sensing Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Clegg, S.M. [Physical Chemistry and Applied Spectroscopy, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)

2015-08-01

We report on efforts to perform theoretical modeling of the emission spectrum measured from a basalt sample. We compare our calculations with measurements that were made to provide standards for the ChemCam instrument on the Mars Science Laboratory. We find that to obtain good agreement between modeling and the measurement, it is necessary to determine atomic and ionic level populations via a multi-element approach in which the free electron density that is created influences all the species within the plasma. Calculations that consider each element separately are found to be in poorer agreement with the measured spectrum, indicating that the ‘matrix effect’ term often used to describe the influence of other species on the emission spectrum from a given element is due to the influence of the global electron density of the plasma. We explore the emission features in both the visible and near-infrared wavelength ranges, and also examine radiation transport effects for some of the most intense features found in the basalt spectrum. Finally, we also provide comparisons of the ChemCam measurement with new high-resolution spectral measurements. - Highlights: • LIBS basalt spectrum • Ab-initio theoretical modeling • Discussion of matrix effects • Discussion of radiation transport effects • High-resolution measurements of Basalt.

RESOLVING THE ACTIVE GALACTIC NUCLEUS AND HOST EMISSION IN THE MID-INFRARED USING A MODEL-INDEPENDENT SPECTRAL DECOMPOSITION

Energy Technology Data Exchange (ETDEWEB)

Hernán-Caballero, Antonio; Alonso-Herrero, Almudena [Instituto de Física de Cantabria, CSIC-UC, Avenida de los Castros s/n, E-39005, Santander (Spain); Hatziminaoglou, Evanthia [European Southern Observatory, Karl-Schwarzschild-Strasse 2, D-85748 Garching bei München (Germany); Spoon, Henrik W. W. [Cornell University, CRSR, Space Sciences Building, Ithaca, NY 14853 (United States); Almeida, Cristina Ramos [Instituto de Astrofísica de Canarias, Vía Láctea s/n, E-38205 La Laguna, Tenerife (Spain); Santos, Tanio Díaz [Núcleo de Astronomía de la Facultad de Ingeniería, Universidad Diego Portales, Av. Ejército Libertador 441, Santiago (Chile); Hönig, Sebastian F. [School of Physics and Astronomy, University of Southampton, Southampton SO18 1BJ (United Kingdom); González-Martín, Omaira [Centro de Radioastronomía y Astrofísica (CRyA-UNAM), 3-72 (Xangari), 8701, Morelia (Mexico); Esquej, Pilar, E-mail: ahernan@ifca.unican.es [Departamento de Astrofísica, Facultad de CC. Físicas, Universidad Complutense de Madrid, E-28040 Madrid (Spain)

2015-04-20

We present results on the spectral decomposition of 118 Spitzer Infrared Spectrograph (IRS) spectra from local active galactic nuclei (AGNs) using a large set of Spitzer/IRS spectra as templates. The templates are themselves IRS spectra from extreme cases where a single physical component (stellar, interstellar, or AGN) completely dominates the integrated mid-infrared emission. We show that a linear combination of one template for each physical component reproduces the observed IRS spectra of AGN hosts with unprecedented fidelity for a template fitting method with no need to model extinction separately. We use full probability distribution functions to estimate expectation values and uncertainties for observables, and find that the decomposition results are robust against degeneracies. Furthermore, we compare the AGN spectra derived from the spectral decomposition with sub-arcsecond resolution nuclear photometry and spectroscopy from ground-based observations. We find that the AGN component derived from the decomposition closely matches the nuclear spectrum with a 1σ dispersion of 0.12 dex in luminosity and typical uncertainties of ∼0.19 in the spectral index and ∼0.1 in the silicate strength. We conclude that the emission from the host galaxy can be reliably removed from the IRS spectra of AGNs. This allows for unbiased studies of the AGN emission in intermediate- and high-redshift galaxies—currently inaccesible to ground-based observations—with archival Spitzer/IRS data and in the future with the Mid-InfraRed Instrument of the James Webb Space Telescope. The decomposition code and templates are available at http://denebola.org/ahc/deblendIRS.

Nonlocal Response of Metallic Nanospheres Probed by Light, Electrons, and Atoms

DEFF Research Database (Denmark)

Christensen, Thomas; Yan, Wei; Raza, Søren

2014-01-01

Inspired by recent measurements on individual metallic nanospheres that cannot be explained with traditional classical electrodynamics, we theoretically investigate the effects of nonlocal response by metallic nanospheres in three distinct settings: atomic spontaneous emission, electron energy loss...... blueshifted surface plasmon but also an infinite series of bulk plasmons that have no counterpart in a local-response approximation. We show that these increasingly blueshifted multipole plasmons become spectrally more prominent at shorter probe-to-surface separations and for decreasing nanosphere radii...

Enzyme activity measurement via spectral evolution profiling and PARAFAC

DEFF Research Database (Denmark)

Baum, Andreas; Meyer, Anne S.; Garcia, Javier Lopez

2013-01-01

The recent advances in multi-way analysis provide new solutions to traditional enzyme activity assessment. In the present study enzyme activity has been determined by monitoring spectral changes of substrates and products in real time. The method relies on measurement of distinct spectral...... fingerprints of the reaction mixture at specific time points during the course of the whole enzyme catalyzed reaction and employs multi-way analysis to detect the spectral changes. The methodology is demonstrated by spectral evolution profiling of Fourier Transform Infrared (FTIR) spectral fingerprints using...

The SiC hardware of the Sentinel-2 multi spectral instrument

Science.gov (United States)

Bougoin, Michel; Lavenac, Jérôme

2017-11-01

The Sentinel-2 mission is a major part of the GMES (Global Monitoring for Environment and Security) program which has been set up by the European Union, on a joint initiative with the European Space Agency. A pair of identical satellites will observe the earth from a sun-synchronous orbit at 786 km altitude. Astrium is the prime contractor of the satellites and their payload. The MultiSpectral Instrument features a "all-SiC" TMA (Three Mirror Anastygmat) telescope. MSI will provide optical images in 13 spectral bands, in the visible and also the near infra-red range, with a 10 to 60 m resolution and a 290 km wide swath. The Boostec® SiC material is used mainly for its high specific stiffness (Youngs modulus / density) and its high thermal stability (thermal conductivity / coefficient of thermal expansion) which allow to reduce the distortions induced by thermo-elastic stresses. Its high mechanical properties as well as the relevant technology enable to make not only the mirrors but also the structure which holds them and the elements of the focal plane (including some detectors packaging). Due to the required large size, accuracy and shape complexity, developing and manufacturing some of these SiC parts required innovative manufacturing approach. It is reviewed in the present paper.

Photon echo with a few photons in two-level atoms

International Nuclear Information System (INIS)

Bonarota, M; Dajczgewand, J; Louchet-Chauvet, A; Le Gouët, J-L; Chanelière, T

2014-01-01

To store and retrieve signals at the single photon level, various photon echo schemes have resorted to complex preparation steps involving ancillary shelving states in multi-level atoms. For the first time, we experimentally demonstrate photon echo operation at such a low signal intensity without any preparation step, which allows us to work with mere two-level atoms. This simplified approach relies on the so-coined ‘revival of silenced echo’ (ROSE) scheme. Low noise conditions are obtained by returning the atoms to the ground state before the echo emission. In the present paper we manage ROSE in photon counting conditions, showing that very strong control fields can be compatible with extremely weak signals, making ROSE consistent with quantum memory requirements. (paper)

State-of-the art comparability of corrected emission spectra. 2. Field laboratory assessment of calibration performance using spectral fluorescence standards.

Science.gov (United States)

Resch-Genger, Ute; Bremser, Wolfram; Pfeifer, Dietmar; Spieles, Monika; Hoffmann, Angelika; DeRose, Paul C; Zwinkels, Joanne C; Gauthier, François; Ebert, Bernd; Taubert, R Dieter; Voigt, Jan; Hollandt, Jörg; Macdonald, Rainer

2012-05-01

In the second part of this two-part series on the state-of-the-art comparability of corrected emission spectra, we have extended this assessment to the broader community of fluorescence spectroscopists by involving 12 field laboratories that were randomly selected on the basis of their fluorescence measuring equipment. These laboratories performed a reference material (RM)-based fluorometer calibration with commercially available spectral fluorescence standards following a standard operating procedure that involved routine measurement conditions and the data evaluation software LINKCORR developed and provided by the Federal Institute for Materials Research and Testing (BAM). This instrument-specific emission correction curve was subsequently used for the determination of the corrected emission spectra of three test dyes, X, QS, and Y, revealing an average accuracy of 6.8% for the corrected emission spectra. This compares well with the relative standard uncertainties of 4.2% for physical standard-based spectral corrections demonstrated in the first part of this study (previous paper in this issue) involving an international group of four expert laboratories. The excellent comparability of the measurements of the field laboratories also demonstrates the effectiveness of RM-based correction procedures.

High-resolution spectral analysis of light from neutral beams and ion source plasmas

International Nuclear Information System (INIS)

McNeill, D.H.; Kim, J.

1980-05-01

The spectral distributions of Balmer alpha emission from 7- and 22-cm-diam neutral hydrogen beams have been measured with a Fabry-Perot interferometer to obtain information on the beam energy, divergence, and species composition. Results of these measurements are compared with other data on the beam properties to evaluate high-resolution spectroscopy as a beam diagnostic technique. Measurements on ion source plasmas and on beam-produced background plasmas yield average neutral atom energies of approximately 0.3 and 2.5 eV, respectively

Effects of spectral variation on the device performance of copper indium diselenide and multi-crystalline silicon photovoltaic modules

Energy Technology Data Exchange (ETDEWEB)

Okullo, W.; Munji, M.K.; Vorster, F.J.; van Dyk, E.E. [Department of Physics, Nelson Mandela Metropolitan University, Box 77000, Port Elizabeth (South Africa)

2011-02-15

We present results of an experimental investigation of the effects of the daily spectral variation on the device performance of copper indium diselenide and multi-crystalline silicon photovoltaic modules. Such investigations are of importance in characterization of photovoltaic devices. The investigation centres on the analysis of outdoor solar spectral measurements carried out at 10 min intervals on clear-sky days. We have shown that the shift in the solar spectrum towards infrared has a negative impact on the device performance of both modules. The spectral bands in the visible region contribute more to the short circuit current than the bands in the infrared region while the ultraviolet region contributes least. The quantitative effects of the spectral variation on the performance of the two photovoltaic modules are reflected on their respective device performance parameters. The decrease in the visible and the increase in infrared of the late afternoon spectra in each case account for the decreased current collection and hence power and efficiency of both modules. (author)

Model of opacity and emissivity of non-equilibrium plasma

International Nuclear Information System (INIS)

Politov V Y

2008-01-01

In this work the model describing absorption and emission properties of the non-equilibrium plasma is presented. It is based on the kinetics equations for populations of the ground, singly and doubly excited states of multi-charged ions. After solving these equations, the states populations together with the spectroscopic data, supplied in the special database for a lot ionization stages, are used for building the spectral distributions of plasma opacity and emissivity in STA approximation. Results of kinetics simulation are performed for such important X-ray converter as gold, which is investigated intensively in ICF-experiments

Integrative Multi-Spectral Sensor Device for Far-Infrared and Visible Light Fusion

Science.gov (United States)

Qiao, Tiezhu; Chen, Lulu; Pang, Yusong; Yan, Gaowei

2018-06-01

Infrared and visible light image fusion technology is a hot spot in the research of multi-sensor fusion technology in recent years. Existing infrared and visible light fusion technologies need to register before fusion because of using two cameras. However, the application effect of the registration technology has yet to be improved. Hence, a novel integrative multi-spectral sensor device is proposed for infrared and visible light fusion, and by using the beam splitter prism, the coaxial light incident from the same lens is projected to the infrared charge coupled device (CCD) and visible light CCD, respectively. In this paper, the imaging mechanism of the proposed sensor device is studied with the process of the signals acquisition and fusion. The simulation experiment, which involves the entire process of the optic system, signal acquisition, and signal fusion, is constructed based on imaging effect model. Additionally, the quality evaluation index is adopted to analyze the simulation result. The experimental results demonstrate that the proposed sensor device is effective and feasible.

Inductively coupled plasma for atomic emission spectroscopy at the Savannah River Plant

International Nuclear Information System (INIS)

Coleman, J.T.

1986-01-01

The Savannah River Plant atomic emission spectroscopy laboratory has been in operation for over 30 years. Routine analytical methods and instrumentation are being replaced with current technology. Laboratory renovation will include the installation of contained dual excitation sources (inductively coupled plasma and d-c arc) with a direct reading spectrometer. The instrument will be used to provide impurity analyses of plutonium, uranium, and other nuclear fuel cycle materials

Mid-infrared, long wave infrared (4-12 μm) molecular emission signatures from pharmaceuticals using laser-induced breakdown spectroscopy (LIBS).

Science.gov (United States)

Yang, Clayton S-C; Brown, Ei E; Kumi-Barimah, Eric; Hommerich, Uwe H; Jin, Feng; Trivedi, Sudhir B; Samuels, Alan C; Snyder, A Peter

2014-01-01

In an effort to augment the atomic emission spectra of conventional laser-induced breakdown spectroscopy (LIBS) and to provide an increase in selectivity, mid-wave to long-wave infrared (IR), LIBS studies were performed on several organic pharmaceuticals. Laser-induced breakdown spectroscopy signature molecular emissions of target organic compounds are observed for the first time in the IR fingerprint spectral region between 4-12 μm. The IR emission spectra of select organic pharmaceuticals closely correlate with their respective standard Fourier transform infrared spectra. Intact and/or fragment sample molecular species evidently survive the LIBS event. The combination of atomic emission signatures derived from conventional ultraviolet-visible-near-infrared LIBS with fingerprints of intact molecular entities determined from IR LIBS promises to be a powerful tool for chemical detection.

Problems, possibilities and limitations of inductively coupled plasma atomic emission spectrometry in the determination of platinum, palladium and rhodium in samples with different matrix composition

Energy Technology Data Exchange (ETDEWEB)

Petrova, P.; Velichkov, S. [Institute of General and Inorganic Chemistry, Bulgarian Academy of Sciences, Acad. G. Bontchev Str. bl. 11, 1113 Sofia (Bulgaria); Velitchkova, N. [Geological Institute, Bulgarian Academy of Sciences, Acad. G. Bontchev Str., bl.24, 1113 Sofia (Bulgaria); Havezov, I. [Institute of General and Inorganic Chemistry, Bulgarian Academy of Sciences, Acad. G. Bontchev Str. bl. 11, 1113 Sofia (Bulgaria); Daskalova, N., E-mail: das15482@svr.igic.bas.b [Institute of General and Inorganic Chemistry, Bulgarian Academy of Sciences, Acad. G. Bontchev Str. bl. 11, 1113 Sofia (Bulgaria)

2010-02-15

The economic and geological importance of platinum group of elements has led to the development of analytical methods to quantify them in different types of samples. In the present paper the quantitative information for spectral interference in radial viewing 40.68 MHz inductively coupled plasma atomic emission spectrometry in the determination of Pt, Pd and Rh in the presence of complex matrix, containing Al, Ca, Fe, Mg, Mn, P and Ti as matrix constituents was obtained. The database was used for optimum line selections. By using the selected analysis lines the following detection limits in ng g{sup -1} were obtained: Pt 1700, Pd-1440, Rh-900. The reached detection limits determine the possibilities and limitation of the direct ICP-AES method in the determination of Pt, Pd and Rh in geological and environmental materials. The database for spectral interferences in the presence of aluminum can be used for the determination of platinum group of elements in car catalysts. The accuracy of the analytical results was experimentally demonstrated by two certified reference materials that were analyzed: SARM 7, Pt ore and recycled auto-catalyst certified reference material SRM 2556.

Visual perception enhancement for detection of cancerous oral tissue by multi-spectral imaging

International Nuclear Information System (INIS)

Wang, Hsiang-Chen; Tsai, Meng-Tsan; Chiang, Chun-Ping

2013-01-01

Color reproduction systems based on the multi-spectral imaging technique (MSI) for both directly estimating reflection spectra and direct visualization of oral tissues using various light sources are proposed. Images from three oral cancer patients were taken as the experimental samples, and spectral differences between pre-cancerous and normal oral mucosal tissues were calculated at three time points during 5-aminolevulinic acid photodynamic therapy (ALA-PDT) to analyze whether they were consistent with disease processes. To check the successful treatment of oral cancer with ALA-PDT, oral cavity images by swept source optical coherence tomography (SS-OCT) are demonstrated. This system can also reproduce images under different light sources. For pre-cancerous detection, the oral images after the second ALA-PDT are assigned as the target samples. By using RGB LEDs with various correlated color temperatures (CCTs) for color difference comparison, the light source with a CCT of about 4500 K was found to have the best ability to enhance the color difference between pre-cancerous and normal oral mucosal tissues in the oral cavity. Compared with the fluorescent lighting commonly used today, the color difference can be improved by 39.2% from 16.5270 to 23.0023. Hence, this light source and spectral analysis increase the efficiency of the medical diagnosis of oral cancer and aid patients in receiving early treatment. (paper)

Visual perception enhancement for detection of cancerous oral tissue by multi-spectral imaging

Science.gov (United States)

Wang, Hsiang-Chen; Tsai, Meng-Tsan; Chiang, Chun-Ping

2013-05-01

Color reproduction systems based on the multi-spectral imaging technique (MSI) for both directly estimating reflection spectra and direct visualization of oral tissues using various light sources are proposed. Images from three oral cancer patients were taken as the experimental samples, and spectral differences between pre-cancerous and normal oral mucosal tissues were calculated at three time points during 5-aminolevulinic acid photodynamic therapy (ALA-PDT) to analyze whether they were consistent with disease processes. To check the successful treatment of oral cancer with ALA-PDT, oral cavity images by swept source optical coherence tomography (SS-OCT) are demonstrated. This system can also reproduce images under different light sources. For pre-cancerous detection, the oral images after the second ALA-PDT are assigned as the target samples. By using RGB LEDs with various correlated color temperatures (CCTs) for color difference comparison, the light source with a CCT of about 4500 K was found to have the best ability to enhance the color difference between pre-cancerous and normal oral mucosal tissues in the oral cavity. Compared with the fluorescent lighting commonly used today, the color difference can be improved by 39.2% from 16.5270 to 23.0023. Hence, this light source and spectral analysis increase the efficiency of the medical diagnosis of oral cancer and aid patients in receiving early treatment.

Frequency position modulation using multi-spectral projections

Science.gov (United States)

Goodman, Joel; Bertoncini, Crystal; Moore, Michael; Nousain, Bryan; Cowart, Gregory

2012-10-01

In this paper we present an approach to harness multi-spectral projections (MSPs) to carefully shape and locate tones in the spectrum, enabling a new and robust modulation in which a signal's discrete frequency support is used to represent symbols. This method, called Frequency Position Modulation (FPM), is an innovative extension to MT-FSK and OFDM and can be non-uniformly spread over many GHz of instantaneous bandwidth (IBW), resulting in a communications system that is difficult to intercept and jam. The FPM symbols are recovered using adaptive projections that in part employ an analog polynomial nonlinearity paired with an analog-to-digital converter (ADC) sampling at a rate at that is only a fraction of the IBW of the signal. MSPs also facilitate using commercial of-the-shelf (COTS) ADCs with uniform-sampling, standing in sharp contrast to random linear projections by random sampling, which requires a full Nyquist rate sample-and-hold. Our novel communication system concept provides an order of magnitude improvement in processing gain over conventional LPI/LPD communications (e.g., FH- or DS-CDMA) and facilitates the ability to operate in interference laden environments where conventional compressed sensing receivers would fail. We quantitatively analyze the bit error rate (BER) and processing gain (PG) for a maximum likelihood based FPM demodulator and demonstrate its performance in interference laden conditions.

Atomic phenomena in dense plasmas

International Nuclear Information System (INIS)

Weisheit, J.C.

1981-03-01

The following chapters are included: (1) the plasma environment, (2) perturbations of atomic structure, (3) perturbations of atomic collisions, (4) formation of spectral lines, and (5) dielectronic recombination

Time variations of oxygen emission lines and solar wind dynamic parameters in low latitude region

Science.gov (United States)

Jamlongkul, P.; Wannawichian, S.; Mkrtichian, D.; Sawangwit, U.; A-thano, N.

2017-09-01

Aurora phenomenon is an effect of collision between precipitating particles with gyromotion along Earth’s magnetic field and Earth’s ionospheric atoms or molecules. The particles’ precipitation occurs normally around polar regions. However, some auroral particles can reach lower latitude regions when they are highly energetic. A clear emission from Earth’s aurora is mostly from atomic oxygen. Moreover, the sun’s activities can influence the occurrence of the aurora as well. This work studies time variations of oxygen emission lines and solar wind parameters, simultaneously. The emission’s spectral lines were observed by Medium Resolution Echelle Spectrograph (MRES) along with 2.4 meters diameter telescope at Thai National Observatory, Intanon Mountain, Chiang Mai, Thailand. Oxygen (OI) emission lines were calibrated by Dech-Fits spectra processing program and Dech95 2D image processing program. The correlations between oxygen emission lines and solar wind dynamics will be analyzed. This result could be an evidence of the aurora in low latitude region.

Cellular organization and spectral diversity of GFP-like proteins in live coral cells studied by single and multiphoton imaging and microspectroscopy

Science.gov (United States)

Salih, Anya; Cox, Guy C.; Larkum, Anthony W.

2003-07-01

Tissues of many marine invertebrates of class Anthozoa contain intensely fluorescent or brightly coloured pigments. These pigments belong to a family of photoactive proteins closely related to Green Fluorescent Protein (GFP), and their emissions range from blue to red wavelengths. The great diversity of these pigments has only recently been realised. To investigate the role of these proteins in corals, we have performed an in vivo fluorescent pigment (FP) spectral and cellular distribution analyses in live coral cells using single and multi-photon laser scanning imaging and microspectroscopy. These analyses revealed that even single colour corals contain spectroscopically heterogeneous pigment mixtures, with 2-5 major colour types in the same area of tissue. They were typically arranged in step-wise light emission energy gradients (e.g. blue, green, yellow, red). The successive overlapping emission-excitation spectral profiles of differently coloured FPs suggested that they were suited for sequential energy coupling. Traces of red FPs (emission = 570-660 nm) were present, even in non-red corals. We confirmed that radiative energy transfer could occur between separate granules of blue and green FPs and that energy transfer was inversely proportional to the square of the distance between them. Multi-photon micro-spectrofluorometric analysis gave significantly improved spectral resolution by restricting FP excitation to a single point in the focal plane of the sample. Pigment heterogeneity at small scales within granules suggested that fluorescence resonance energy transfer (FRET) might be occurring, and we confirmed that this was the case. Thus, energy transfer can take place both radiatively and by FRET, probably functioning in photoprotection by dissipation of excessive solar radiation.

Amplified emission and modified spectral features in an opal hetero-structure mediated by passive defect mode localization

Science.gov (United States)

Rout, Dipak; Kumar, Govind; Vijaya, R.

2018-01-01

A photonic crystal hetero-structure consisting of a passive planar defect of SiO2 thin film sandwiched between two identical opals grown by inward growing self-assembly method using Rhodamine-B dye-doped polystyrene microspheres is studied for the characteristics of dye emission. The optical properties and the defect mode characteristics of the hetero-structure are studied from the reflection and transmission measurements. Laser-induced fluorescence from the hetero-structure showed amplified and spectrally narrowed emission compared to the photonic crystal emphasizing the role of the defect mode and distributed feedback. The enhanced emission is also complemented by the reduction in fluorescence decay time in the case of the hetero-structure in comparison to the 3D photonic crystals.

Separability Analysis of Sentinel-2A Multi-Spectral Instrument (MSI Data for Burned Area Discrimination

Directory of Open Access Journals (Sweden)

Haiyan Huang

2016-10-01

Full Text Available Biomass burning is a global phenomenon and systematic burned area mapping is of increasing importance for science and applications. With high spatial resolution and novelty in band design, the recently launched Sentinel-2A satellite provides a new opportunity for moderate spatial resolution burned area mapping. This study examines the performance of the Sentinel-2A Multi Spectral Instrument (MSI bands and derived spectral indices to differentiate between unburned and burned areas. For this purpose, five pairs of pre-fire and post-fire top of atmosphere (TOA reflectance and atmospherically corrected (surface reflectance images were studied. The pixel values of locations that were unburned in the first image and burned in the second image, as well as the values of locations that were unburned in both images which served as a control, were compared and the discrimination of individual bands and spectral indices were evaluated using parametric (transformed divergence and non-parametric (decision tree approaches. Based on the results, the most suitable MSI bands to detect burned areas are the 20 m near-infrared, short wave infrared and red-edge bands, while the performance of the spectral indices varied with location. The atmospheric correction only significantly influenced the separability of the visible wavelength bands. The results provide insights that are useful for developing Sentinel-2 burned area mapping algorithms.

Multi-octave spectral beam combiner on ultra-broadband photonic integrated circuit platform.

Science.gov (United States)

Stanton, Eric J; Heck, Martijn J R; Bovington, Jock; Spott, Alexander; Bowers, John E

2015-05-04

We present the design of a novel platform that is able to combine optical frequency bands spanning 4.2 octaves from ultraviolet to mid-wave infrared into a single, low M2 output waveguide. We present the design and realization of a key component in this platform that combines the wavelength bands of 350 nm - 1500 nm and 1500 nm - 6500 nm with demonstrated efficiency greater than 90% in near-infrared and mid-wave infrared. The multi-octave spectral beam combiner concept is realized using an integrated platform with silicon nitride waveguides and silicon waveguides. Simulated bandwidth is shown to be over four octaves, and measured bandwidth is shown over two octaves, limited by the availability of sources.

An expression for the atomic fluorescence and thermal-emission intensity under conditions of near saturation and arbitrary self-absorption

NARCIS (Netherlands)

Omenetto, N.; Winefordner, J.D.; Alkemade, C.T.J.

An expression for the effect of self-absorption on the fluorescence and thermal emission intensities is derived by taking into account stimulated emission. A simple, idealized case is considered, consisting of a two level atomic system, in a flame, homogeneous with respect to temperature and

[Study on spectral gain characterization of FWM processes with multi-frequency pumps in photonic crystal fiber].

Science.gov (United States)

Hui, Zhan-Qiang

2011-10-01

Spectral gain induced by four-wave-mixing with multi-frequency pump was investigated by exploiting the data signal and continue lights co-propagation in dispersion flattened high nonlinear photonic crystal fiber (PCF). The effects of wavelength drift of pump lights, polarization state of orthogonal or parallel of pump lights, polarization mismatch of signal light versus orthogonal pump lights, total power of signal and probe light on the spectrum gain were analyzed. The results show that good FWM gain effects with multi-frequency pump can be obtained in 36.4 nm wavelength range when power ratio of pump to probe light is appropriate and with identical polarization. Furthermore, the gain of FWM with multi-frequency pump is very sensitive to polarization fluctuation and the different idle waves obtain different gain with the variation in signal polarization state. Moreover, the impact of pump numbers was investigated. The obtained results would be helpful for further research on ultrahigh-speed all optical signal processing devices exploiting the FWM with multi-frequency pump in PCF for future photonics network.

Computational analyses of spectral trees from electrospray multi-stage mass spectrometry to aid metabolite identification.

Science.gov (United States)

Cao, Mingshu; Fraser, Karl; Rasmussen, Susanne

2013-10-31

Mass spectrometry coupled with chromatography has become the major technical platform in metabolomics. Aided by peak detection algorithms, the detected signals are characterized by mass-over-charge ratio (m/z) and retention time. Chemical identities often remain elusive for the majority of the signals. Multi-stage mass spectrometry based on electrospray ionization (ESI) allows collision-induced dissociation (CID) fragmentation of selected precursor ions. These fragment ions can assist in structural inference for metabolites of low molecular weight. Computational investigations of fragmentation spectra have increasingly received attention in metabolomics and various public databases house such data. We have developed an R package "iontree" that can capture, store and analyze MS2 and MS3 mass spectral data from high throughput metabolomics experiments. The package includes functions for ion tree construction, an algorithm (distMS2) for MS2 spectral comparison, and tools for building platform-independent ion tree (MS2/MS3) libraries. We have demonstrated the utilization of the package for the systematic analysis and annotation of fragmentation spectra collected in various metabolomics platforms, including direct infusion mass spectrometry, and liquid chromatography coupled with either low resolution or high resolution mass spectrometry. Assisted by the developed computational tools, we have demonstrated that spectral trees can provide informative evidence complementary to retention time and accurate mass to aid with annotating unknown peaks. These experimental spectral trees once subjected to a quality control process, can be used for querying public MS2 databases or de novo interpretation. The putatively annotated spectral trees can be readily incorporated into reference libraries for routine identification of metabolites.

Multi-field electron emission pattern of 2D emitter: Illustrated with graphene

Science.gov (United States)

Luo, Ma; Li, Zhibing

2016-11-01

The mechanism of laser-assisted multi-field electron emission of two-dimensional emitters is investigated theoretically. The process is basically a cold field electron emission but having more controllable components: a uniform electric field controls the emission potential barrier, a magnetic field controls the quantum states of the emitter, while an optical field controls electron populations of specified quantum states. It provides a highly orientational vacuum electron line source whose divergence angle over the beam plane is inversely proportional to square root of the emitter height. Calculations are carried out for graphene with the armchair emission edge, as a concrete example. The rate equation incorporating the optical excitation, phonon scattering, and thermal relaxation is solved in the quasi-equilibrium approximation for electron population in the bands. The far-field emission patterns, that inherit the features of the Landau bands, are obtained. It is found that the optical field generates a characteristic structure at one wing of the emission pattern.

Semiclassical multi-phonon theory for atom-surface scattering: Application to the Cu(111) system.

Science.gov (United States)

Daon, Shauli; Pollak, Eli

2015-05-07

The semiclassical perturbation theory of Hubbard and Miller [J. Chem. Phys. 80, 5827 (1984)] is further developed to include the full multi-phonon transitions in atom-surface scattering. A practically applicable expression is developed for the angular scattering distribution by utilising a discretized bath of oscillators, instead of the continuum limit. At sufficiently low surface temperature good agreement is found between the present multi-phonon theory and the previous one-, and two-phonon theory derived in the continuum limit in our previous study [Daon, Pollak, and Miret-Artés, J. Chem. Phys. 137, 201103 (2012)]. The theory is applied to the measured angular distributions of Ne, Ar, and Kr scattered from a Cu(111) surface. We find that the present multi-phonon theory substantially improves the agreement between experiment and theory, especially at the higher surface temperatures. This provides evidence for the importance of multi-phonon transitions in determining the angular distribution as the surface temperature is increased.

On I(5577 Å and I (7620 Å auroral emissions and atomic oxygen densities

Directory of Open Access Journals (Sweden)

R. L. Gattinger

1996-07-01

Full Text Available A model of auroral electron deposition processes has been developed using Monte Carlo techniques to simulate electron transport and energy loss. The computed differential electron flux and pitch angle were compared with in situ auroral observations to provide a check on the accuracy of the model. As part of the energy loss process, a tally was kept of electronic excitation and ionization of the important atomic and molecular states. The optical emission rates from these excited states were computed and compared with auroral observations of η(3914 Å, η(5577 Å, η(7620 Å and η(N2VK. In particular, the roles played by energy transfer from N2(A3Σ+u and by other processes in the excitation of O(1S and O2(b1Σ+g were investigated in detail. It is concluded that the N2(A3Σ+u mechanism is dominant for the production of OI(5577 Å in the peak emission region of normal aurora, although the production efficiency is much smaller than the measured laboratory value; above 150 km electron impact on atomic oxygen is dominant. Atomic oxygen densities in the range of 0.75±0.25 MSIS-86 [O] were derived from the optical comparisons for auroral latitudes in mid-winter for various levels of solar and magnetic activity.

Multi-spectral imager

CSIR Research Space (South Africa)

Stolper, R

2006-02-01

Full Text Available channel are boresighted with two beamsplitter windows; and • The IR system is boresighted. APPLICATION High-voltage environment • Detecting loose strands, bolts and nuts; • Detecting Corona discharges on insulator discs; • Detecting... and locating spark gaps; • Detecting and locating RIV sources; • Audit sub-stations and transmission lines for audio noise and Corona activities. RECORDINGS / APPLICATIONS REPORTING TOOL: MultiSOFT • Image handling software for grabbing, processing...

Investigation of oxygen impurity transport using the O4+ visible spectral line in the Aditya tokamak

International Nuclear Information System (INIS)

Chowdhuri, M.B.; Ghosh, J.; Banerjee, S.; Dey, Ritu; Manchanda, R.; Kumar, Vinay; Vasu, P.; Patel, K.M.; Atrey, P.K.; Shankara Joisa, Y.; Rao, C.V.S.; Tanna, R.L.; Raju, D.; Chattopadhyay, P.K.; Jha, R.; Gupta, C.N.; Bhatt, S.B.; Saxena, Y.C.

2013-01-01

Intense visible lines from Be-like oxygen impurity are routinely observed in the Aditya tokamak. The spatial profile of brightness of a Be-like oxygen spectral line (2p3p 3 D 3 –2p3d 3 F 4 ) at 650.024 nm is used to investigate oxygen impurity transport in typical discharges of the Aditya tokamak. A 1.0 m multi-track spectrometer (Czerny–Turner) capable of simultaneous measurements from eight lines of sight is used to obtain the radial profile of brightness of O 4+ spectral emission. The emissivity profile of O 4+ spectral emission is obtained from the spatial profile of brightness using an Abel-like matrix inversion. The oxygen transport coefficients are determined by reproducing the experimentally measured emissivity profiles of O 4+ , using a one-dimensional empirical impurity transport code, STRAHL. Much higher values of the diffusion coefficient compared with the neo-classical values are observed in both the high magnetic field edge region (D inboard max ∼30 m 2 s -1 ) and the low magnetic field edge region (D outboard max ∼45 m 2 s -1 ) of typical Aditya ohmic plasmas, which seems to be due to fluctuation-induced transport. The diffusion coefficient at the limiter radius in the low-field (outboard) region is typically ∼ twice as high as that at the limiter radius in the high-field (inboard) region. (paper)