Science.gov

Sample records for emission spectroscopy study

  1. Studying Simple Molecular Ionization using Radiation Emission Spectroscopy

    NASA Astrophysics Data System (ADS)

    Proctor, Christopher; Lemmer, Kristina; Western Michigan University Aerospace LaboratoryPlasma Experiments Team

    2015-11-01

    This study focuses on radiation emission from the formation of simple molecular plasma using a DC glow discharge. The purpose is to measure the emission from argon and molecular nitrogen gas as a function of time with an optical emission spectroscopy system operating in kinetic mode as the gases go from their neutral state to ionized state. The end goal of the research is to develop a diagnostic tool that will be used to study the formation of plasma discharges from complex molecules. The kinetic mode of the CCD camera allows for fast data acquisition so that the species present and their relative concentrations as a function of time can be measured as the plasma is forming. The primary difficulty in the development of this diagnostic tool is designing a device and data analysis technique to allow for kinetic mode operation of the CCD camera. Experimental devices have been designed and built to enable the CCD to operate in kinetic mode, including a fiber optic adapter, camera mount, and twin razor blade system. The twin blades allow for the reduction of exposed pixels on the CCD camera and thereby allow the camera to store data on rows of pixels, rather than imaging the entire camera, allowing for faster data transfer. PhD in Aerospace Engineering.

  2. [Study on optical emission spectroscopy of pulse corona methane plasma].

    PubMed

    Li, Jin-Ping; Dai, Bin; Fan, Ting

    2009-07-01

    From experiments of methane pulse corona plasma and plasma emission spectrometry, the emission spectra of methane ranging from 370 to 1 100 nm were recorded and marked with CCD (Charge Coupled Device) grating spectrometry. The ionization products of H, C+, CH, C, C2, C3, C4, C5 and hydrocarbon were confirmed through high purity methane (purity 99.99%) ionized by pulse high voltage of 100 kV and 100 Hz under normal temperature and normal pressure. Through analyzing the experimental emission spectrum of methane plasma, the ionization mechanism, i.e. methane gas was ionized into corona plasma by pulse high voltage, was analyzed and the ionization of free radical CHn (n = 3, 2, 1), carbon and hydrocarbons was given as well. Research results show that the dehydrogenation achieved a high level when methane molecules collide inelastically with high energy electrons, and the hydrogen atoms, hydrogen ions and methane free radicals were synthesized into alkenes, alkynes, alkanes and high polymer of carbon with further inelastic collision of high energy electrons. This experimental spectrum and mechanism analysis can be applied to the research on methane conversion.

  3. Single photon infrared emission spectroscopy: a study of IR emission from UV laser excited PAHs between 3 and 15 micrometers

    NASA Technical Reports Server (NTRS)

    Cook, D. J.; Schlemmer, S.; Balucani, N.; Wagner, D. R.; Harrison, J. A.; Steiner, B.; Saykally, R. J.

    1998-01-01

    Single-photon infrared emission spectroscopy (SPIRES) has been used to measure emission spectra from polycyclic aromatic hydrocarbons (PAHs). A supersonic free-jet expansion has been used to provide emission spectra of rotationally cold and vibrationally excited naphthalene and benzene. Under these conditions, the observed width of the 3.3-micrometers (C-H stretch) band resembles the bandwidths observed in experiments in which emission is observed from naphthalene with higher rotational energy. To obtain complete coverage of IR wavelengths relevant to the unidentified infrared bands (UIRs), UV laser-induced desorption was used to generate gas-phase highly excited PAHs. Lorentzian band shapes were convoluted with the monochromator-slit function in order to determine the widths of PAH emission bands under astrophysically relevant conditions. Bandwidths were also extracted from bands consisting of multiple normal modes blended together. These parameters are grouped according to the functional groups mostly involved in the vibration, and mean bandwidths are obtained. These bandwidths are larger than the widths of the corresponding UIR bands. However, when the comparison is limited to the largest PAHs studied, the bandwidths are slightly smaller than the corresponding UIR bands. These parameters can be used to model emission spectra from PAH cations and cations of larger PAHs, which are better candidate carriers of the UIRs.

  4. Application of optical emission spectroscopy for the SNS H- ion source plasma studies

    NASA Astrophysics Data System (ADS)

    Han, B. X.; Stockli, M. P.; Welton, R. F.; Murray, S. N.; Pennisi, T. R.; Santana, M.

    2015-04-01

    The SNS H- ion source is a dual-frequency RF-driven (13.56-MHz low power continuous RF superimposed by 2-MHz high power pulsed RF with ˜1.0 ms pulse length at 60 Hz), Cs-enhanced ion source. This paper discusses the applications of optical emission spectroscopy for the ion source plasma conditioning, cesiation, failure diagnostics, and studies of plasma build-up and outage issues.

  5. A study of carbonates, sulfates, and phosphates using thermal emission spectroscopy

    NASA Technical Reports Server (NTRS)

    Wenrich, M. L.; Christensen, P. R.

    1993-01-01

    Thermal emission spectroscopy is useful for identifying mineralogies including carbonates, sulfates, and phosphates. Each of these groups of minerals has a distinct emissivity profile that allows for general identification (e.g., carbonate). Laboratory data are being collected that suggest the potential for determining specific composition of these minerals (e.g., calcite, magnesite). Previous studies of Mars suggest that the above groups of minerals should be present. On Mars fine-grained mineralogies are likely to be intimately mixed due to aeolian activity. Mixtures of calcite with palagonite will be studied to determine the volume percent requirement for salt identification and to understand the complexities of fine-grained mixtures observed by thermal emission. Further work with mixtures will include sulfate and phosphate mineralogies.

  6. [Study on Ammonia Emission Rules in a Dairy Feedlot Based on Laser Spectroscopy Detection Method].

    PubMed

    He, Ying; Zhang, Yu-jun; You, Kun; Wang, Li-ming; Gao, Yan-wei; Xu, Jin-feng; Gao, Zhi-ling; Ma, Wen-qi

    2016-03-01

    It needs on-line monitoring of ammonia concentration on dairy feedlot to disclose ammonia emissions characteristics accurately for reducing ammonia emissions and improving the ecological environment. The on-line monitoring system for ammonia concentration has been designed based on Tunable Diode Laser Absorption Spectroscopy (TDLAS) technology combining with long open-path technology, then the study has been carried out with inverse dispersion technique and the system. The ammonia concentration in-situ has been detected and ammonia emission rules have been analyzed on a dairy feedlot in Baoding in autumn and winter of 2013. The monitoring indicated that the peak of ammonia concentration was 6.11 x 10(-6) in autumn, and that was 6.56 x 10(-6) in winter. The concentration results show that the variation of ammonia concentration had an obvious diurnal periodicity, and the general characteristic of diurnal variation was that the concentration was low in the daytime and was high at night. The ammonia emissions characteristic was obtained with inverse dispersion model that the peak of ammonia emissions velocity appeared at noon. The emission velocity was from 1.48 kg/head/hr to 130.6 kg/head/hr in autumn, and it was from 0.004 5 kg/head/hr to 43.32 kg/head/hr in winter which was lower than that in autumn. The results demonstrated ammonia emissions had certain seasonal differences in dairy feedlot scale. In conclusion, the ammonia concentration was detected with optical technology, and the ammonia emissions results were acquired by inverse dispersion model analysis with large range, high sensitivity, quick response without gas sampling. Thus, it's an effective method for ammonia emissions monitoring in dairy feedlot that provides technical support for scientific breeding.

  7. Adhesion and transfer of PTFE to metals studied by auger emission spectroscopy

    NASA Technical Reports Server (NTRS)

    Pepper, S. V.; Buckley, D. H.

    1972-01-01

    The adhesion and transfer of polytetrafluoroethylene (PTFE) to metals in ultrahigh vacuum has been studied using Auger emission spectroscopy. The transfer was effected both by compressive static contact and by sliding contact. The transfer observed after static contact was independent of the chemical constitution of the substrate. Electron induced desorption of the fluorine in the transferred PTFE showed that the fluorine had no chemical interaction with the metal substrate. The coefficient of friction on metals was independent of the chemical constitution of the substrate. However, sliding PTFE on soft metals such as aluminum, generated wear fragments that lodged in the PTFE and machined the substrate.

  8. Application of 57Co emission Mössbauer spectroscopy to studying biocomplexes in frozen solutions

    NASA Astrophysics Data System (ADS)

    Kamnev, A. A.; Kulikov, L. A.; Perfiliev, Yu. D.; Antonyuk, L. P.; Kuzmann, E.; Vértes, A.

    2005-09-01

    Emission Mössbauer spectroscopy with the 57Co isotope was used to study very dilute rapidly frozen aqueous solutions of cobalt(II) complexes with low-molecular-weight biomolecules (aromatic amino acids anthranilic acid and L-tryptophan) and within a sophisticated biopolymer, bacterial glutamine synthetase, a key enzyme of nitrogen metabolism. The appearance of after-effects of the 57Co→57Fe nuclear transformation as well as the coordination properties of the cation and the ligands in the complexes are discussed on the basis of their Mössbauer parameters.

  9. Experimental and theoretical studies of laser-induced breakdown spectroscopy emission from iron oxide: Studies of atmospheric effects

    NASA Astrophysics Data System (ADS)

    Colgan, J.; Barefield, J. E.; Judge, E. J.; Campbell, K.; Johns, H. M.; Kilcrease, D. P.; McInroy, R.; Clegg, S. M.

    2016-08-01

    We report on a comprehensive study of the emission spectra from laser-induced breakdown spectroscopy (LIBS) measurements on iron oxide. Measurements have been made of the emission from Fe2O3 under atmospheres of air, He, and Ar, and at different atmospheric pressures. The effect of varying the time delay of the measurement is also explored. Theoretical calculations were performed to analyze the plasma conditions and find that a reasonably consistent picture of the change in plasma temperature and density for different atmospheric conditions can be reached. We also investigate the sensitivity of the OI 777 nm emission lines to the plasma conditions, something that has not been explored in detail in the previous work. Finally, we also show that LIBS can be used to differentiate between FeO and Fe2O3 by examining the ratio of the intensities of selected Fe emission to O emission lines.

  10. Development of beam emission spectroscopy for turbulence transport study in Heliotron J

    NASA Astrophysics Data System (ADS)

    Kobayashi, S.; Ohshima, S.; Matsuda, H.; Lu, X. X.; Kokubu, D.; Ida, K.; Kobayashi, T.; Yoshinuma, M.; Kado, S.; Oishi, T.; Nagasaki, K.; Okada, H.; Minami, T.; Yamamoto, S.; Nakamura, Y.; Ishizawa, A.; Kenmochi, N.; Otani, Y.; Konoshima, S.; Mizuuchi, T.

    2016-11-01

    This paper describes the development study of the beam emission spectroscopy (BES) for the turbulent transport study in Heliotron J. Modification of the sightlines (10 × 4 for edge and 10 × 2 for edge) enables us to obtain 2-dimensional BES imaging. The cooling effect on the reduction in the electrical noise of avalanche photodiode (APD) assembly has been investigated using a refrigerant cooling system. When the temperature of the APD element has set to be -20 °C, the electrical noise can be reduced more than 50%. The measurement error of the phase difference in the case of low signal level has been tested by two light-emitting diode lamps. The APD cooling has an effect to improve the measurement error at the low signal level of APD.

  11. Studies on optical emission spectroscopy of nitriding plasma and characterization of nitrided steel

    NASA Astrophysics Data System (ADS)

    Sharma, Manash Kumar

    Plasma in nature is abundant and appears quite beautiful in colour as can be seen in glow of sun and auroras. Plasma produced in laboratories is also quite interesting as a correspondence of the naturally occurring plasmas from a glow discharge to a tokamak. However, plasmas tuned to special conditions have been successfully utilized for material processing, of which, plasma nitriding is one and foremost. The work of the thesis focuses on the setting up of a plasma nitriding system with various diagnostics applied to plasma and plasma treated stainless steels. Emission spectroscopy and probe diagnostics are applied to study the optical and plasma properties whereas austenitic stainless steels are characterized by x-ray diffraction (XRD) and hardness test in order to demonstrate the application of the process. The optical and plasma properties during nitriding are motivating, as these properties will lead to conditions for the formation of surface layer. The formation of iron and chromium nitrides is another important asset of the plasma nitriding process, which is tested by XRD technique, while the surface hardness is tested by hardness test. Optical properties are found from optical emission spectroscopy (OES) in terms of emission intensities and wavelengths. Langmuir probe (LP) is used for finding variations of plasma parameters with respect to process parameters and to make a comparison of plasma parameters with those of optical and discharge parameters. A correlation between OES and material characterization properties is sought in order to make a clear understanding of the process. In Chapter 1, introduction to plasma, the possible applications with relevance to plasma nitriding and spectroscopy are described. Plasma nitriding (termed in the title as nitriding plasma for convenience) has emerged as a powerful tool in modifying surface properties of a material without affecting the bulk properties. The various advantages over a conventional gas nitriding

  12. Electronic transitions and fermi edge singularity in polar heterostructures studied by absorption and emission spectroscopy

    NASA Astrophysics Data System (ADS)

    Pandey, S.; Cavalcoli, D.; Minj, A.; Fraboni, B.; Cavallini, A.; Gamarra, P.; Poisson, M. A.

    2012-12-01

    Optically induced electronic transitions in nitride based polar heterostructures have been investigated by absorption and emission spectroscopy. Surface photovoltage (SPV), photocurrent (PC), and photo luminescence spectroscopy have been applied to high quality InAlN/AlN/GaN structures to study the optical properties of two dimensional electron gas. Energy levels within the two dimensional electron gas (2DEG) well at the interface between the GaN and AlN have been directly observed by SPV and PC. Moreover, a strong enhancement of the photoluminescence intensity due to holes recombining with electrons at the Fermi Energy, known as fermi energy singularity, has been observed. These analyses have been carried out on InAlN/AlN/GaN heterojunctions with the InAlN barrier layer having different In content, a parameter which affects the energy levels within the 2DEG well as well as the optical signal intensity. The measured energy values are in a very good agreement with the ones obtained by Schrödinger-Poisson simulations.

  13. Use of LEED, Auger emission spectroscopy and field ion microscopy in microstructural studies

    NASA Technical Reports Server (NTRS)

    Ferrante, J.; Buckley, D. H.; Pepper, S. V.; Brainard, W. A.

    1972-01-01

    Surface research tools such as LEED, Auger emission spectroscopy analysis, and field ion microscopy are discussed. Examples of their use in studying adhesion, friction, wear, and lubrication presented. These tools have provided considerable insight into the basic nature of solid surface interactions. The transfer of metals from one surface to another at the atomic level has been observed and studied with each of these devices. The field ion microscope has been used to study polymer-metal interactions and Auger analysis to study the mechanism of polymer adhesion to metals. LEED and Auger analysis have identified surface segregation of alloying elements and indicated the influence of these elements in metallic adhesion. LEED and Auger analysis have assisted in adsorption studies in determining the structural arrangement and quantity of adsorbed species present in making an understanding of the influence of these species on adhesion possible. These devices are assisting in the furtherance of understanding of the fundamental mechanism involved in the adhesion, friction, wear, and lubrication processes.

  14. [Application of atomic emission spectroscopy analysis in the atmospheric pressure plasma polishing process study].

    PubMed

    Wang, Bo; Zhang, Ju-Fan; Dong, Shen

    2008-07-01

    The atmospheric pressure plasma polishing (APPP) is a novel precision machining technology. It performs the atom scale material removal based on low temperature plasma chemical reactions. As the machining process is chemical in nature, it avoids the surface/subsurface defects usually formed in conventional mechanical machining processes. APPP firstly introduces a capacitance coupled radio frequency (RF) plasma torch to generate reactive plasma and excite chemical reactions further. The removal process is a complicated integrating action which tends to be affected by many factors, such as the gas ratio, the RF power and so on. Therefore, to improve the machining quality, all the aspects should be considered and studied, to establish the foundation for further model building and theoretical analysis. The atomic emission spectroscopy analysis was used to study the process characteristics. A commercial micro spectrometer was used to collect the spectrograms under different parameters, by comparing which the influence of the RF power and gas ratio was initially studied. The analysis results indicate that an increase in RF power results in a higher removal rate within a certain range. The gas ratio doesn't show obvious influence on the removal rate and surface roughness in initial experiments, but the element compositions detected by X-ray photoelectron spectroscopy technology on the machined surfaces under different ratios really indicate distinct difference. Then the theoretical analysis revealed the corresponding electron transition orbits of the excited reactive fluorine atoms, which is necessary for further mechanism research and apparatus improvement. Then the initial process optimization was made based on the analysis results, by which the Ra 0.6 nm surface roughness and 32 mm3 x min(-1) removal rate were achieved on silicon wafers.

  15. Optical absorption and emission spectroscopy studies of ammonia-containing plasmas

    NASA Astrophysics Data System (ADS)

    Kang, S. J.; Donnelly, V. M.

    2007-05-01

    The chemistry of NH3/Ar/He plasmas was investigated, using a combination of ultraviolet (UV) optical absorption spectroscopy (OAS) and optical emission spectroscopy (OES). Absolute NH3 number densities in 1 Torr plasmas were measured by OAS as a function of inductively coupled plasma power and substrate heater temperature (Th). OES and actinometry were used to determine semi-quantitative H-atom density. A 'self-actinometry' method was introduced to measure the absolute number density of N2 that formed following the dissociation of NH3 and secondary reactions. In this approach, small amounts of N2 are added to the NH3-containing plasma, leading to an increase in the N2(C 3 Πu → B 3 Πg) emission intensity. This provides an accurate calibration factor for converting relative N2 emission intensities into absolute number densities. The number densities of NH3 were found to decrease with increasing power and Th, reaching >90% dissociation at 400 W and 900 K. N2 densities increased with power and Th. The majority of dissociated NH3 was converted to N2 (i.e. the total nitrogen content was conserved in the sum of these two species). The major hydrogen-containing species appeared to be H2; however, a substantial amount of H-atoms (comparable to H2) was present at the highest powers.

  16. X-ray emission spectroscopy.

    PubMed

    Bergmann, Uwe; Glatzel, Pieter

    2009-01-01

    We describe the chemical information that can be obtained by means of hard X-ray emission spectroscopy (XES). XES is presented as a technique that is complementary to X-ray absorption spectroscopy (XAS) and that provides valuable information with respect to the electronic structure (local charge- and spin-density) as well as the ligand environment of a 3d transition metal. We address non-resonant and resonant XES and present results that were recorded on Mn model systems and the Mn(4)Ca-cluster in the oxygen evolving complex of photosystem II. A brief description of the instrumentation is given with an outlook toward future developments.

  17. [Studies on the remote measurement of the emission of formaldehyde by mobile differential optical absorption spectroscopy].

    PubMed

    Wu, Feng-Cheng; Xie, Pin-Hua; Li, Ang; Si, Fu-Qi; Dou, Ke; Liu, Yu; Xu, Jin; Wang, Jie

    2011-11-01

    Formaldehyde (HCHO) is the most abundant carbonyl compounds that play an important role in atmospheric chemistry and photochemical reactions. Formaldehyde is an important indicator of atmospheric reactivity and urban atmospheric aerosol precursors. In the present paper, the emission of formaldehyde from chemical area was measured using the mobile differential optical absorption spectroscopy (DOAS). This instrument uses the zenith scattered sunlight as the light source with successful sampling in the area loop. Vertical column density was retrieved by this system, combined with the meteorological wind field and car speed information, the emission of formaldehyde in the area was estimated. The authors carried out the measuring experiment in one chemical plant in Beijing using this technology. The result showed that the average value of the flux of formaldehyde in this area was 605 kg x h(-1) during the measuring period.

  18. Positronium emission spectroscopy

    SciTech Connect

    Howell, R.H.; Tuomisaari, M.

    1988-08-01

    Measurements of the intensity, velocity, and angular distribution of positronium emitted from solid samples of metals and insulators have been performed using the intense, pulsed positron beam from the 100 MeV electron linac. From these data it is possible to determine properties of both the surface interactions and volume potentials of the materials studied. Examples of these effects will be given using measurements of positronium time of flight performed with the Livermore intense positron beam. The time of flight data have been augmented by positron lifetime and angular correlation measurements performed with the beam. Measurements resulting in workfunctions, deformation potentials and surface interaction effects will be reported for both metals and insulators. 18 refs., 2 figs.

  19. Chemical Modification of Graphene Oxide by Nitrogenation: An X-ray Absorption and Emission Spectroscopy Study

    PubMed Central

    Chuang, Cheng-Hao; Ray, Sekhar C.; Mazumder, Debarati; Sharma, Surbhi; Ganguly, Abhijit; Papakonstantinou, Pagona; Chiou, Jau-Wern; Tsai, Huang-Ming; Shiu, Hung-Wei; Chen, Chia-Hao; Lin, Hong-Ji; Guo, Jinghua; Pong, Way-Faung

    2017-01-01

    Nitrogen-doped graphene oxides (GO:Nx) were synthesized by a partial reduction of graphene oxide (GO) using urea [CO(NH2)2]. Their electronic/bonding structures were investigated using X-ray absorption near-edge structure (XANES), valence-band photoemission spectroscopy (VB-PES), X-ray emission spectroscopy (XES) and resonant inelastic X-ray scattering (RIXS). During GO:Nx synthesis, different nitrogen-bonding species, such as pyrrolic/graphitic-nitrogen, were formed by replacing of oxygen-containing functional groups. At lower N-content (2.7 at%), pyrrolic-N, owing to surface and subsurface diffusion of C, N and NH is deduced from various X-ray spectroscopies. In contrast, at higher N-content (5.0 at%) graphitic nitrogen was formed in which each N-atom trigonally bonds to three distinct sp2-hybridized carbons with substitution of the N-atoms for C atoms in the graphite layer. Upon nitrogen substitution, the total density of state close to Fermi level is increased to raise the valence-band maximum, as revealed by VB-PES spectra, indicating an electron donation from nitrogen, molecular bonding C/N/O coordination or/and lattice structure reorganization in GO:Nx. The well-ordered chemical environments induced by nitrogen dopant are revealed by XANES and RIXS measurements. PMID:28186190

  20. Chemical Modification of Graphene Oxide by Nitrogenation: An X-ray Absorption and Emission Spectroscopy Study.

    PubMed

    Chuang, Cheng-Hao; Ray, Sekhar C; Mazumder, Debarati; Sharma, Surbhi; Ganguly, Abhijit; Papakonstantinou, Pagona; Chiou, Jau-Wern; Tsai, Huang-Ming; Shiu, Hung-Wei; Chen, Chia-Hao; Lin, Hong-Ji; Guo, Jinghua; Pong, Way-Faung

    2017-02-10

    Nitrogen-doped graphene oxides (GO:Nx) were synthesized by a partial reduction of graphene oxide (GO) using urea [CO(NH2)2]. Their electronic/bonding structures were investigated using X-ray absorption near-edge structure (XANES), valence-band photoemission spectroscopy (VB-PES), X-ray emission spectroscopy (XES) and resonant inelastic X-ray scattering (RIXS). During GO:Nx synthesis, different nitrogen-bonding species, such as pyrrolic/graphitic-nitrogen, were formed by replacing of oxygen-containing functional groups. At lower N-content (2.7 at%), pyrrolic-N, owing to surface and subsurface diffusion of C, N and NH is deduced from various X-ray spectroscopies. In contrast, at higher N-content (5.0 at%) graphitic nitrogen was formed in which each N-atom trigonally bonds to three distinct sp(2)-hybridized carbons with substitution of the N-atoms for C atoms in the graphite layer. Upon nitrogen substitution, the total density of state close to Fermi level is increased to raise the valence-band maximum, as revealed by VB-PES spectra, indicating an electron donation from nitrogen, molecular bonding C/N/O coordination or/and lattice structure reorganization in GO:Nx. The well-ordered chemical environments induced by nitrogen dopant are revealed by XANES and RIXS measurements.

  1. Chemical Modification of Graphene Oxide by Nitrogenation: An X-ray Absorption and Emission Spectroscopy Study

    NASA Astrophysics Data System (ADS)

    Chuang, Cheng-Hao; Ray, Sekhar C.; Mazumder, Debarati; Sharma, Surbhi; Ganguly, Abhijit; Papakonstantinou, Pagona; Chiou, Jau-Wern; Tsai, Huang-Ming; Shiu, Hung-Wei; Chen, Chia-Hao; Lin, Hong-Ji; Guo, Jinghua; Pong, Way-Faung

    2017-02-01

    Nitrogen-doped graphene oxides (GO:Nx) were synthesized by a partial reduction of graphene oxide (GO) using urea [CO(NH2)2]. Their electronic/bonding structures were investigated using X-ray absorption near-edge structure (XANES), valence-band photoemission spectroscopy (VB-PES), X-ray emission spectroscopy (XES) and resonant inelastic X-ray scattering (RIXS). During GO:Nx synthesis, different nitrogen-bonding species, such as pyrrolic/graphitic-nitrogen, were formed by replacing of oxygen-containing functional groups. At lower N-content (2.7 at%), pyrrolic-N, owing to surface and subsurface diffusion of C, N and NH is deduced from various X-ray spectroscopies. In contrast, at higher N-content (5.0 at%) graphitic nitrogen was formed in which each N-atom trigonally bonds to three distinct sp2-hybridized carbons with substitution of the N-atoms for C atoms in the graphite layer. Upon nitrogen substitution, the total density of state close to Fermi level is increased to raise the valence-band maximum, as revealed by VB-PES spectra, indicating an electron donation from nitrogen, molecular bonding C/N/O coordination or/and lattice structure reorganization in GO:Nx. The well-ordered chemical environments induced by nitrogen dopant are revealed by XANES and RIXS measurements.

  2. Electron capture and emission spectroscopy to study surface and interface magnetism

    NASA Astrophysics Data System (ADS)

    Rau, Carl

    1994-07-01

    Electron capture spectroscopy (ECS) and spin-polarized electron emission spectroscopy (SPEES) are extremely sensitive techniques to probe surface magnetic properties. Ultra-thin bct Fe(100)(1×1)/Pd(100) films exhibit 2D Ising critical behavior. The surface electron spin polarization (ESP) follows precisely the exact solution of the 2D Ising model as given by Yang. The average magnetization of the topmost surface layer is enhanced by 32% compared to that of bulk layers. Pd Auger electrons emitted from the Fe/Pd interface are spin-polarized, and the ESP is oriented parallel to that of emitted Fe Auger electrons. At surfaces of 5nm thick hcp Tb(0001)/W(110) films, strong surface magnetic surface anisotropies are found. The onset of ferromagnetism occurs ≈30 K above the bulk Curie temperature (220K) of Tb. For clean Fe and Fe/Pd surfaces, the ESP of low-energy (≈2 eV) emitted electrons is substantially enhanced by Stoner excitations. The existence of a nonzero ESP at O/Fe surfaces demonstrates the absence of a magnetically dead surface layer.

  3. Dynamics of Bloch State Positronium Emission from MOF Targets Studied via Rydberg TOF Spectroscopy

    NASA Astrophysics Data System (ADS)

    Piñeiro Escalera, Alina; Jones, Adric; Mills, Allen

    2016-05-01

    Recent advances in the efficient production and detection of Rydberg positronium (Ps) have made it possible to perform energy- and angle- resolved time-of-flight (TOF) spectroscopy with Ps. We report here TOF measurements of Ps emission from the metal-oxide framework (MOF) targets, MOF-5 and ZIF-8. MOFs are a recently synthesized class of chemical structures, characterized by high long-range order and large surface area to volume ratios (i.e., they are highly porous and uniform, crystalline materials). Ps is found to be emitted predominantly in a series of monoenergetic peaks, providing clear evidence of Ps Bloch states. Measuring the relative populations of the monoenergetic peaks, as a function of implantation energy and target temperature, provides insight into the target-dependent dynamics of Bloch state Ps. Work supported by the U.S. National Science Foundation Grants No. PHY 1206100 and No. PHY 1040590 and the National Science Foundation Graduate Research Fellowship Progam (NSF-GRFP). DOE BES DE-FG02-13ER46972 (MOF-5 synthesis and characterization).

  4. Double pulse laser induced breakdown spectroscopy: Experimental study of lead emission intensity dependence on the wavelengths and sample matrix

    NASA Astrophysics Data System (ADS)

    Piscitelli S, V.; Martínez L., M. A.; Fernández C., A. J.; González, J. J.; Mao, X. L.; Russo, R. E.

    2009-02-01

    Lead (Pb) emission intensity (atomic line 405.78 nm) dependence on the sample matrix (metal alloy) was studied by means of collinear double pulse (DP)-laser induced breakdown spectroscopy (LIBS). The measurement of the emission intensity produced by three different wavelength combinations (i.e. I:532 nm-II:1064 nm, I:532 nm-II:532 nm, and I:532 nm-II:355 nm) from three series of standard reference materials showed that the lead atomic line 405.78 nm emission intensity was dependent on the sample matrix for all the combination of wavelengths, however reduced dependency was found for the wavelength combination I:532 nm-II:355 nm. Two series of standard reference materials from the National Institute of Standards and Technology (NIST) and one series from the British Chemical Standards (BCS) were used for these experiments. Calibration curves for lead ablated from NIST 626-630 ("Zn 95Al 4Cu 1") provided higher sensitivity (slope) than those calibration curves produced from NIST 1737-1741 ("Zn 99.5Al 0.5") and with the series BCS 551-556 ("Cu 87Sn 11"). Similar trends between lead emission intensity (calibration curve sensitivities) and reported variations in plasma temperatures caused by the differing ionization potentials of the major and minor elements in these samples were established.

  5. Study of dynamic emission spectra from lubricant films in an elastohydrodynamic contact using Fourier transform spectroscopy

    NASA Technical Reports Server (NTRS)

    Lauer, J. L.

    1978-01-01

    Infrared emission spectra were obtained through a diamond window from lubricating fluids in an operating sliding elastohydrodynamic contact and analyzed by comparison with static absorption spectra under similar pressures. Different loads, shear rates and temperatures were used. Most of the spectra exhibited polarization characteristics, indicating directional alignment of the lubricant in the EHD contact. Among the fluids studied were a "traction" fluid, an advanced ester, and their mixtures, a synthetic paraffin, a naphthenic reference fluid (N-1), both neat and containing 1 percent of p-tricresyl phosphate as an anti-wear additive, and a C-ether. Traction properties were found to be nearly proportional to mixture composition for traction fluid and ester mixtures. The anti-wear additive reduced traction and fluid temperature under low loads but increased them under higher loads, giving rise to formation of a friction polymer.

  6. Cobalt(II) complexation with small biomolecules as studied by 57Co emission Mössbauer spectroscopy

    NASA Astrophysics Data System (ADS)

    Kamnev, Alexander A.; Perfiliev, Yurii D.; Kulikov, Leonid A.; Tugarova, Anna V.; Kovács, Krisztina; Homonnay, Zoltán; Kuzmann, Ernő

    2017-02-01

    In the emission (57Co) variant of Mössbauer spectroscopy (EMS), the 57Co radionuclide (with a half-life of 9 months) is used that undergoes a nuclear decay 57Co → 57Fe via electron capture followed by the emission of a γ-quantum, the energy of which is modified by the chemical state and the close coordination environment of the parent 57Co atom. While EMS has been used largely in materials science and nuclear chemistry, its high sensitivity can also be of great advantage in revealing fine structural features and for speciation analysis of biological complexes, whenever the 57Co2 + cation can be used directly as the coordinating metal or as a substitute for native cobalt or other metal ions. As such EMS applications are yet rare, in order to reliably interpret emission spectra of sophisticated 57Co2 +-doped biosystems, model EMS studies of simple cobalt biocomplexes are necessary. In this work, EMS spectroscopic data are analysed and discussed for 57Co2 + complexes with a range of small biomolecules of different structures, including 4-n-hexylresorcinol, homoserine lactone and a few amino acids (spectra measured in rapidly frozen dilute aqueous solutions or in the dried state at T = 80 K). The EMS data obtained are discussed with regard to the available literature data related to the coordination modes of the biocomplexes under study.

  7. Aqueous solutions of uranium(VI) as studied by time-resolved emission spectroscopy: a round-robin test.

    PubMed

    Billard, Isabelle; Ansoborlo, Eric; Apperson, Kathleen; Arpigny, Sylvie; Azenha, M Emilia; Birch, David; Bros, Pascal; Burrows, Hugh D; Choppin, Gregory; Couston, Laurent; Dubois, Veronique; Fanghänel, Thomas; Geipel, Gerhard; Hubert, Solange; Kim, Jae I; Kimura, Takaumi; Klenze, Reinhardt; Kronenberg, Andreas; Kumke, Michael; Lagarde, Gerard; Lamarque, Gerard; Lis, Stefan; Madic, Charles; Meinrath, Gunther; Moulin, Christophe; Nagaishi, Ryuji; Parker, David; Plancque, Gabriel; Scherbaum, Franz; Simoni, Eric; Sinkov, Sergei; Viallesoubranne, Carole

    2003-08-01

    Results of an inter-laboratory round-robin study of the application of time-resolved emission spectroscopy (TRES) to the speciation of uranium(VI) in aqueous media are presented. The round-robin study involved 13 independent laboratories, using various instrumentation and data analysis methods. Samples were prepared based on appropriate speciation diagrams and, in general, were found to be chemically stable for at least six months. Four different types of aqueous uranyl solutions were studied: (1) acidic medium where UO2(2+)aq is the single emitting species, (2) uranyl in the presence of fluoride ions, (3) uranyl in the presence of sulfate ions, and (4) uranyl in aqueous solutions at different pH, promoting the formation of hydrolyzed species. Results between the laboratories are compared in terms of the number of decay components, luminescence lifetimes, and spectral band positions. The successes and limitations of TRES in uranyl analysis and speciation in aqueous solutions are discussed.

  8. Adsorption, X-ray Diffraction, Photoelectron, and Atomic Emission Spectroscopy Benchmark Studies for the Eighth Industrial Fluid Properties Simulation Challenge.

    PubMed

    Ross, Richard B; Aeschliman, David B; Ahmad, Riaz; Brennan, John K; Brostrom, Myles L; Frankel, Kevin A; Moore, Jonathan D; Moore, Joshua D; Mountain, Raymond D; Poirier, Derrick M; Thommes, Matthias; Shen, Vincent K; Schultz, Nathan E; Siderius, Daniel W; Smith, Kenneth D

    2016-02-01

    The primary goal of the eighth industrial fluid properties simulation challenge was to test the ability of molecular simulation methods to predict the adsorption of organic adsorbates in activated carbon materials. The challenge focused on the adsorption of perfluorohexane in the activated carbon standard BAM-P109 (Panne and Thünemann 2010). Entrants were challenged to predict the adsorption of perfluorohexane in the activated carbon at a temperature of 273 K and at relative pressures of 0.1, 0.3, and 0.6. The relative pressure (P/Po) is defined as that relative to the bulk saturation pressure predicted by the fluid model at a given temperature (273 K in this case). The predictions were judged by comparison to a set of experimentally determined values, which are published here for the first time and were not disclosed to the entrants prior to the challenge. Benchmark experimental studies, described herein, were also carried out and provided to entrants in order to aid in the development of new force fields and simulation methods to be employed in the challenge. These studies included argon, carbon dioxide, and water adsorption in the BAM-P109 activated carbon as well as X-ray diffraction, X-ray microtomography, photoelectron spectroscopy, and atomic emission spectroscopy studies of BAM-P109. Several concurrent studies were carried out for the BAM-P108 activated carbon (Panne and Thünemann 2010). These are included in the current manuscript for comparison.

  9. Adsorption, X-ray Diffraction, Photoelectron, and Atomic Emission Spectroscopy Benchmark Studies for the Eighth Industrial Fluid Properties Simulation Challenge*+

    PubMed Central

    Ross, Richard B.; Aeschliman, David B.; Ahmad, Riaz; Brennan, John K.; Brostrom, Myles L.; Frankel, Kevin A.; Moore, Jonathan D.; Moore, Joshua D.; Mountain, Raymond D.; Poirier, Derrick M.; Thommes, Matthias; Shen, Vincent K.; Schultz, Nathan E.; Siderius, Daniel W.; Smith, Kenneth D.

    2016-01-01

    The primary goal of the eighth industrial fluid properties simulation challenge was to test the ability of molecular simulation methods to predict the adsorption of organic adsorbates in activated carbon materials. The challenge focused on the adsorption of perfluorohexane in the activated carbon standard BAM-P109 (Panne and Thünemann 2010). Entrants were challenged to predict the adsorption of perfluorohexane in the activated carbon at a temperature of 273 K and at relative pressures of 0.1, 0.3, and 0.6. The relative pressure (P/Po) is defined as that relative to the bulk saturation pressure predicted by the fluid model at a given temperature (273 K in this case). The predictions were judged by comparison to a set of experimentally determined values, which are published here for the first time and were not disclosed to the entrants prior to the challenge. Benchmark experimental studies, described herein, were also carried out and provided to entrants in order to aid in the development of new force fields and simulation methods to be employed in the challenge. These studies included argon, carbon dioxide, and water adsorption in the BAM-P109 activated carbon as well as X-ray diffraction, X-ray microtomography, photoelectron spectroscopy, and atomic emission spectroscopy studies of BAM-P109. Several concurrent studies were carried out for the BAM-P108 activated carbon (Panne and Thünemann 2010). These are included in the current manuscript for comparison. PMID:27840543

  10. Vibrational motions associated with primary processes in bacteriorhodopsin studied by coherent infrared emission spectroscopy.

    PubMed

    Groma, Géza I; Colonna, Anne; Martin, Jean-Louis; Vos, Marten H

    2011-03-16

    The primary energetic processes driving the functional proton pump of bacteriorhodopsin take place in the form of complex molecular dynamic events after excitation of the retinal chromophore into the Franck-Condon state. These early events include a strong electronic polarization, skeletal stretching, and all-trans-to-13-cis isomerization upon formation of the J intermediate. The effectiveness of the photoreaction is ensured by a conical intersection between the electronic excited and ground states, providing highly nonadiabatic coupling to nuclear motions. Here, we study real-time vibrational coherences associated with these motions by analyzing light-induced infrared emission from oriented purple membranes in the 750-1400 cm(-)(1) region. The experimental technique applied is based on second-order femtosecond difference frequency generation on macroscopically ordered samples that also yield information on phase and direction of the underlying motions. Concerted use of several analysis methods resulted in the isolation and characterization of seven different vibrational modes, assigned as C-C stretches, out-of-plane methyl rocks, and hydrogen out-of-plane wags, whereas no in-plane H rock was found. Based on their lifetimes and several other criteria, we deduce that the majority of the observed modes take place on the potential energy surface of the excited electronic state. In particular, the direction sensitivity provides experimental evidence for large intermediate distortions of the retinal plane during the excited-state isomerization process.

  11. Emission Mössbauer spectroscopy study of fluence dependence of paramagnetic relaxation in Mn/Fe implanted ZnO

    NASA Astrophysics Data System (ADS)

    Masenda, H.; Geburt, S.; Bharuth-Ram, K.; Naidoo, D.; Gunnlaugsson, H. P.; Johnston, K.; Mantovan, R.; Mølholt, T. E.; Ncube, M.; Shayestehaminzadeh, S.; Gislason, H. P.; Langouche, G.; Ólafsson, S.; Ronning, C.

    2016-12-01

    Emission Mössbauer Spectroscopy following the implantation of radioactive precursor isotope 57Mn+ ( T 1/2= 1.5 min) into ZnO single crystals at ISOLDE/CERN shows that a large fraction of 57Fe atoms produced in the 57Mn beta decay is created as paramagnetic Fe3+ with relatively long spin-lattice relaxation times. Here we report on ZnO pre-implanted with 56Fe to fluences of 2×1013, 5×10 13 and 8 × 1013 ions/cm2 in order to investigate the dependence of the paramagnetic relaxation rate of Fe3+ on fluence. The spectra are dominated by magnetic features displaying paramagnetic relaxation effects. The extracted spin-lattice relaxation rates show a slight increase with increasing ion fluence at corresponding temperatures and the area fraction of Fe3+ at room temperature reaches a maximum contribution of 80(3)% in the studied fluence range.

  12. Theoretical and experimental studies on the analytical applications of flame infrared emission spectroscopy

    SciTech Connect

    Lam, C.K.

    1992-01-01

    A mathematical model was developed for the temperature dependence of the flame/furnace infrared emission (FIRE) produced by the antisymmetric stretching vibration of carbon dioxide. The model can be used to predict the detector performance as a function of the temperature of the excitation source. Thermospray and cross-flow pneumatic nebulizers were studied for interfacing a FIRE radiometer to a high performance liquid chromatograph (HPLC). Due to the large quantities of liquid mobile phase introduced into the burner, the temperature of the H[sub 2]/air flame was changed significantly. The detector could be configured in carbon- or chlorine-specific modes. When the carbon-specific mode was employed, the mobile phase was restricted to deionized water. With the chlorine-specific mode, combustible organic mobile phases could be used and the detector could selectively determine mixtures of chlorinated hydrocarbons. Flame background caused by the combustion of carbon-containing mobile phases could be electronically subtracted by using dual channel FIRE radiometer. Typical detection limits for both kinds of interface are in the range of [mu]g s[sup [minus]1]. The FIRE radiometer can be interfaced to an HPLC to form dissolved carbon dioxide which is then purged by H[sub 2] gas through a special purge chamber. Sodium peroxydisulfate (Na[sub 2]S[sub 2]O[sub 8]), in the presence of silver nitrate, was employed as an oxidizing agent to oxidize carboxylic acids and sugars to carbon dioxide. The specially designed purge chamber can also be used in both process analysis and flow injection analysis (FIA) for the determination of total inorganic carbon, purgeable organic carbon in aqueous samples and the available chlorine in bleach liquors. Nonvolatile organics can be determined by means of sample pretreatment with sodium peroxydisulfate catalyzed with silver at elevated temperature. Hydrogen/nitrous oxide was investigated as an alternative fuel/oxidant mixture.

  13. Midinfrared spectroscopy of synthetic olivines: Thermal emission, specular and diffuse reflectance, and attenuated total reflectance studies of forsterite to fayalite

    NASA Astrophysics Data System (ADS)

    Lane, Melissa D.; Glotch, Timothy D.; Dyar, M. Darby; Pieters, Carle M.; Klima, Rachel; Hiroi, Takahiro; Bishop, Janice L.; Sunshine, Jessica

    2011-08-01

    Synthetic olivine samples ranging in composition from forsterite to fayalite are analyzed in the midinfrared using thermal emission, specular and diffuse reflectance, and attenuated total reflectance spectroscopies to study the spectral effects of Mg-Fe solid solution. For each method, fundamental bands gradually change in position and strength from Mg2SiO4 at larger wave numbers to Fe2SiO4 at smaller wave numbers. Each spectrum is diagnostic of chemistry within the continuum, as previously noted. In this study, 10 identified fundamental bands are traceable across the solid solution series for each technique. In pelletized sample spectra, the 10 bands shift approximately linearly in position by as little as 11 to as much as 64 cm-1. In powdered sample spectra, the bands shift by as little as 12 to as much as 74 cm-1 (disregarding one outlier point). Moreover, for every spectral technique, an even larger linear shift is identified of a specific emissivity maximum/reflectivity minimum (the flection position). From forsterite to fayalite, this flection position shifts by at least 88 cm-1, which is, on average, 48% more than the largest fundamental band shift within the same data set for the pelletized spectra and 44% more for the powdered spectra. Also the R2 and 2σ values of the best fit line for the flection position shift (versus Fo#) generally were as good as or routinely better than those of the fundamental bands. Thus, the flection position should be considered as a means of determining Mg-Fe olivine composition when using thermal emission, specular reflectance, diffuse reflectance, or attenuated total reflectance spectroscopic data.

  14. Transient surface photoconductivity of GaAs emitter studied by terahertz pump-emission spectroscopy

    NASA Astrophysics Data System (ADS)

    Shi, Yulei; Zhou, Qing-li; Zhang, Cunlin

    2010-11-01

    The ultrafast carrier dynamics and surface photoconductivity of unbiased semi-insulating GaAs have been investigated in detail by using terahertz pump-emission technique. Through theoretical modeling based on Hertz vector potential, it is found that transient photoconductivity plays a very important role in the temporal waveform of terahertz radiation pulse. Anomalous enhancement in both terahertz radiation and transient photoconductivity is observed subsequent to the excitation of pump pulse, and our modeling gives successful analyses for the dynamics of photogenerated carriers in the GaAs. We attribute these phenomena to carrier capture in the EL2 centers. Moreover, the pump power- and temperaturedependent measurements are also performed to verify this model.

  15. X-ray Emission Spectroscopy to Study Ligand Valence Orbitals in Mn Coordination Complexes

    SciTech Connect

    Smolentsev, Grigory; Soldatov, Alexander V; Messinger, Johannes; Merz, Kathrin; Weyhermuller, Thomas; Bergmann, Uwe; Pushkar, Yulia; Yano, Junko; Yachandra, Vittal K.; Glatzel, Pieter

    2009-03-02

    We discuss a spectroscopic method to determine the character of chemical bonding and for the identification of metal ligands in coordination and bioinorganic chemistry. It is based on the analysis of satellite lines in X-ray emission spectra that arise from transitions between valence orbitals and the metal ion 1s level (valence-to-core XES). The spectra, in connection with calculations based on density functional theory (DFT), provide information that is complementary to other spectroscopic techniques, in particular X-ray absorption (XANES and EXAFS). The spectral shape is sensitive to protonation of ligands and allows ligands, which differ only slightly in atomic number (e.g., C, N, O...), to be distinguished. A theoretical discussion of the main spectral features is presented in terms of molecular orbitals for a series of Mn model systems: [Mn(H2O)6]2+, [Mn(H2O)5OH]+, [Mn(H2O)5NH2]+, and [Mn(H2O)5NH3]2+. An application of the method, with comparison between theory and experiment, is presented for the solvated Mn2+ ion in water and three Mn coordination complexes, namely [LMn(acac)N3]BPh4, [LMn(B2O3Ph2)(ClO4)], and [LMn(acac)N]BPh4, where L represents 1,4,7-trimethyl-1,4,7-triazacyclononane, acac stands for the 2,4-pentanedionate anion, and B2O3Ph2 represents the 1,3-diphenyl-1,3-dibora-2-oxapropane-1,3-diolato dianion.

  16. Mid infrared emission spectroscopy of carbon plasma.

    PubMed

    Nemes, Laszlo; Brown, Ei Ei; S-C Yang, Clayton; Hommerich, Uwe

    2017-01-05

    Mid infrared time-resolved emission spectra were recorded from laser-induced carbon plasma. These spectra constitute the first study of carbon materials LIB spectroscopy in the mid infrared range. The carbon plasma was induced using a Q-switched Nd: YAG laser. The laser beam was focused to high purity graphite pellets mounted on a translation stage. Mid infrared emission from the plasma in an atmospheric pressure background gas was detected by a cooled HgCdTe detector in the range 4.4-11.6μm, using long-pass filters. LIB spectra were taken in argon, helium and also in air. Despite a gate delay of 10μs was used there were strong backgrounds in the spectra. Superimposed on this background broad and noisy emission bands were observed, the form and position of which depended somewhat on the ambient gas. The spectra were digitally smoothed and background corrected. In argon, for instance, strong bands were observed around 4.8, 6.0 and 7.5μm. Using atomic spectral data by NIST it could be concluded that carbon, argon, helium and nitrogen lines from neutral and ionized atoms are very weak in this spectral region. The width of the infrared bands supports molecular origin. The infrared emission bands were thus compared to vibrational features of carbon molecules (excluding C2) of various sizes on the basis of previous carbon cluster infrared absorption and emission spectroscopic analyses in the literature and quantum chemical calculations. Some general considerations are given about the present results.

  17. Mid infrared emission spectroscopy of carbon plasma

    NASA Astrophysics Data System (ADS)

    Nemes, Laszlo; Brown, Ei Ei; Yang, Clayton S.-C.; Hommerich, Uwe

    2017-01-01

    Mid infrared time-resolved emission spectra were recorded from laser-induced carbon plasma. These spectra constitute the first study of carbon materials LIB spectroscopy in the mid infrared range. The carbon plasma was induced using a Q-switched Nd: YAG laser. The laser beam was focused to high purity graphite pellets mounted on a translation stage. Mid infrared emission from the plasma in an atmospheric pressure background gas was detected by a cooled HgCdTe detector in the range 4.4-11.6 μm, using long-pass filters. LIB spectra were taken in argon, helium and also in air. Despite a gate delay of 10 μs was used there were strong backgrounds in the spectra. Superimposed on this background broad and noisy emission bands were observed, the form and position of which depended somewhat on the ambient gas. The spectra were digitally smoothed and background corrected. In argon, for instance, strong bands were observed around 4.8, 6.0 and 7.5 μm. Using atomic spectral data by NIST it could be concluded that carbon, argon, helium and nitrogen lines from neutral and ionized atoms are very weak in this spectral region. The width of the infrared bands supports molecular origin. The infrared emission bands were thus compared to vibrational features of carbon molecules (excluding C2) of various sizes on the basis of previous carbon cluster infrared absorption and emission spectroscopic analyses in the literature and quantum chemical calculations. Some general considerations are given about the present results.

  18. Infrared emission spectroscopy of HBr

    SciTech Connect

    Braun, V. . Centre for Molecular Beams and Laser Chemistry); Bernath, P.F. . Centre for Molecular Beams and Laser Chemistry Univ. of Arizona, Tucson, AZ . Dept. of Chemistry)

    1994-10-01

    The vibration-rotation emission spectrum of HBr was recorded with a Fourier transform spectrometer. Line positions for the 1-0 and 2-1 bands were measured for both H[sup 79]Br and H[sup 81]Br. A pure rotation emission spectrum of HBr was also obtained, and rotational lines for v = 0 were measured. The two sets of data, when combined with previously measured submillimeter-wave pure rotational transitions, yielded a set of improved rotational constants for H[sup 79]Br and H[sup 81]Br.

  19. Raman scattering or fluorescence emission? Raman spectroscopy study on lime-based building and conservation materials.

    PubMed

    Kaszowska, Zofia; Malek, Kamilla; Staniszewska-Slezak, Emilia; Niedzielska, Karina

    2016-12-05

    This work presents an in-depth study on Raman spectra excited with 1064 and 532nm lasers of lime binders employed in the past as building materials and revealed today as valuable conservation materials. We focus our interest on the bands of strong intensity, which are present in the spectra of all binders acquired with laser excitation at 1064nm, but absent in the corresponding spectra acquired with laser excitation at 532nm. We suggest, that the first group of spectra represents fluorescence phenomena of unknown origin and the second true Raman scattering. In our studies, we also include two other phases of lime cycle, i.e. calcium carbonate (a few samples of calcite of various origins) and calcium oxide (quicklime) to assess how structural and chemical transformations of lime phases affect the NIR-Raman spectral profile. Furthermore, we analyse a set of carbonated limewashes and lime binders derived from old plasters to give an insight into their spectral characteristics after excitation with the 1064nm laser line. NIR-Raman micro-mapping results are also presented to reveal the spatial distribution of building materials and fluorescent species in the cross-section of plaster samples taken from a 15th century chapel. Our study shows that the Raman analysis can help identify lime-based building and conservation materials, however, a caution is advised in the interpretation of the spectra acquired using 1064nm excitation.

  20. Raman scattering or fluorescence emission? Raman spectroscopy study on lime-based building and conservation materials

    NASA Astrophysics Data System (ADS)

    Kaszowska, Zofia; Malek, Kamilla; Staniszewska-Slezak, Emilia; Niedzielska, Karina

    2016-12-01

    This work presents an in-depth study on Raman spectra excited with 1064 and 532 nm lasers of lime binders employed in the past as building materials and revealed today as valuable conservation materials. We focus our interest on the bands of strong intensity, which are present in the spectra of all binders acquired with laser excitation at 1064 nm, but absent in the corresponding spectra acquired with laser excitation at 532 nm. We suggest, that the first group of spectra represents fluorescence phenomena of unknown origin and the second true Raman scattering. In our studies, we also include two other phases of lime cycle, i.e. calcium carbonate (a few samples of calcite of various origins) and calcium oxide (quicklime) to assess how structural and chemical transformations of lime phases affect the NIR-Raman spectral profile. Furthermore, we analyse a set of carbonated limewashes and lime binders derived from old plasters to give an insight into their spectral characteristics after excitation with the 1064 nm laser line. NIR-Raman micro-mapping results are also presented to reveal the spatial distribution of building materials and fluorescent species in the cross-section of plaster samples taken from a 15th century chapel. Our study shows that the Raman analysis can help identify lime-based building and conservation materials, however, a caution is advised in the interpretation of the spectra acquired using 1064 nm excitation.

  1. Adhesion and transfer of polytetrafluorethylene to metals studied by Auger emission spectroscopy

    NASA Technical Reports Server (NTRS)

    Pepper, S. V.; Buckley, D. H.

    1972-01-01

    The adhesion and transfer of polytetrafluoroethylene (PTFE) to metals in ultrahigh vacuum were studied. The transfer was effected both by compressive static contact and by sliding contact. The transfer observed after static contact was independent of the chemical constitution of the substrate. Electron-induced desorption of the fluorine in the transferred PTFE showed that the fluorine had no chemical interaction with the metal substrate. The coefficient of friction on metals was independent of the chemical constitution of the substrate. However, sliding PTFE on soft metals, such as aluminum, generated wear fragments that lodged in the PTFE and machined the substrate.

  2. Secondary Electron Emission Spectroscopy of Diamond Surfaces

    NASA Technical Reports Server (NTRS)

    Krainsky, Isay L.; Asnin, Vladimir M.; Petukhov, Andre G.

    1999-01-01

    This report presents the results of the secondary electron emission spectroscopy study of hydrogenated diamond surfaces for single crystals and chemical vapor-deposited polycrystalline films. One-electron calculations of Auger spectra of diamond surfaces having various hydrogen coverages are presented, the major features of the experimental spectra are explained, and a theoretical model for Auger spectra of hydrogenated diamond surfaces is proposed. An energy shift and a change in the line shape of the carbon core-valence-valence (KVV) Auger spectra were observed for diamond surfaces after exposure to an electron beam or by annealing at temperatures higher than 950 C. This change is related to the redistribution of the valence-band local density of states caused by hydrogen desorption from the surface. A strong negative electron affinity (NEA) effect, which appeared as a large, narrow peak in the low-energy portion of the spectrum of the secondary electron energy distribution, was also observed on the diamond surfaces. A fine structure in this peak, which was found for the first time, reflected the energy structure of the bottom of the conduction band. Further, the breakup of the bulk excitons at the surface during secondary electron emission was attributed to one of the features of this structure. The study demonstrated that the NEA type depends on the extent of hydrogen coverage of the diamond surface, changing from the true type for the completely hydrogenated surface to the effective type for the partially hydrogenated surface.

  3. Optical Emission Spectroscopy in an Unmagnetized Plasma

    NASA Astrophysics Data System (ADS)

    Milhone, Jason; Cooper, Christopher; Desangles, Victor; Nornberg, Mark; Seidlitz, Blair; Forest, Cary; WiPAL Team

    2015-11-01

    An optical emission spectroscopic analysis has been developed to measure electron temperature, neutral burnout, and Zeff in Ar and He plasmas in the Wisconsin plasma astrophysics laboratory (WiPAL). The WiPAL vacuum chamber is a 3 meter diameter spherical vessel lined with 3000 SmCo permanent magnets (B > 3 kG) that create an axisymmetric multi-cusp ring for confining the plasma. WiPAL is designed to study unmagnetized plasmas that are hot (Te > 10 eV), dense (ne >1018), and with high ionization fraction. Electron temperature and density can be measured via Langmuir probes. However, probes can disturb the plasma, be difficult to interpret, and become damaged by large heat loads from the plasma. A low cost non-invasive spectroscopy system capable of scanning the plasma via a linear stage has been installed to study plasma properties. From the neutral particle emission, the neutral burnout and estimated neutral temperature can be inferred. A modified coronal model with metastable states is being implemented to determine Te for Ar plasmas.

  4. Optical emission spectroscopy of atmospheric pressure microwave plasmas

    SciTech Connect

    Jia Haijun; Fujiwara, Hiroyuki; Kondo, Michio; Kuraseko, Hiroshi

    2008-09-01

    The optical emission behaviors of Ar, He, and Ar+He plasmas generated in air using an atmospheric pressure microwave plasma source have been studied employing optical emission spectroscopy (OES). Emissions from various source gas species and air were observed. The variations in the intensities and intensity ratios of specific emissions as functions of the microwave power and gas flow rate were analyzed to investigate the relationship between the emission behavior and the plasma properties. We find that dependence of the emission behavior on the input microwave power is mainly determined by variations in electron density and electron temperature in the plasmas. On the other hand, under different gas flow rate conditions, changes in the density of the source gas atoms also significantly affect the emissions. Interestingly, when plasma is generated using an Ar+He mixture, emissions from excited He atoms disappear while a strong H{sub {alpha}} signal appears. The physics behind these behaviors is discussed in detail.

  5. Laser-Induced-Emission Spectroscopy In Hg/Ar Discharge

    NASA Technical Reports Server (NTRS)

    Maleki, Lutfollah; Blasenheim, Barry J.; Janik, Gary R.

    1992-01-01

    Laser-induced-emission (LIE) spectroscopy used to probe low-pressure mercury/argon discharge to determine influence of mercury atoms in metastable 6(Sup3)P(Sub2) state on emission of light from discharge. LIE used to study all excitation processes affected by metastable population, including possible effects on excitation of atoms, ions, and buffer gas. Technique applied to emissions of other plasmas. Provides data used to make more-accurate models of such emissions, exploited by lighting and laser industries and by laboratories studying discharges. Also useful in making quantitative measurements of relative rates and cross sections of direct and two-step collisional processes involving metastable level.

  6. Photoelectron Emission Spectroscopy of Liquid Water.

    DTIC Science & Technology

    1981-04-01

    correlated to solvation free energies for H2O+(aq) and OH (aq)., DD ,FO*M 1473 EDITIOOF INOV so iS OBSOLETE Unclassified SECURITY CLASSIFICATION OF THIS PAGE...Photoelectron spectroscopy Reorganization free energy Water, liquid 20. ABSTRACT (Chlnw am ef We, aid* it nooe"mr and 1iEru’h hr 190k le 6) The threshold... energy Et a 10.06 eV (0.002 @V standard deviation) is detemined for phot~oelectron emission by litquid water and is correlated with Et a 8.45 eV for

  7. THz Emission Spectroscopy for THz Spintronics

    NASA Astrophysics Data System (ADS)

    Jarik Huisman, Thomas; Rasing, Theo

    2017-01-01

    Spintronics is used as the standard for the readout of magnetically stored data and also has commercial applications for writing data. The generation, control and detection of spin-polarized currents, spin-dependent electric transport, and pure spin currents on the subpicosecond (10-12 s) timescale are the next challenges in spintronics. Terahertz (THz, 1012 Hz) emission spectroscopy has proven to be an excellent tool for investigating these challenges. In this short review, we outline the functioning of this spectroscopic technique and its recent applications to spintronics.

  8. Applications of UV Spatial Heterodyne Spectroscopy for High Spectral Resolution Studies of Diffuse Emission Line Sources in the Solar System

    NASA Astrophysics Data System (ADS)

    Harris, W.; Roesler, F.; Mierkiewicz, E.; Corliss, J.

    2003-05-01

    A Spatial Heterodyne Spectrometer (SHS) instrument combines high etendue and high spectral resolution in a compact package that is very effective for the study of diffuse low surface brightness emissions. SHS instruments require no telescope to achieve high sensitivity on extended sources and may be designed with fields of view exceeding 1 degree and spectral resolutions exceeding 100000. This combination makes them well suited to many solar system targets including comets, the interplanetary medium, and planetary atmospheres/coronas, using platforms from sounding rockets to remote probes. We are currently developing two variations of the SHS. The first of these is a new form of all-reflective, common-path SHS optimized for the study of FUV emission lines where transmitting optics will introduce an unacceptable attenuation of the incident beam. Secondly we are developing a multiorder variation of the SHS, where a customized high order grating is used to overlap integer orders of multiple target emission lines that can then be separated using a transform technique or with order separation filters. In this presentation we will describe the basic SHS technique, the design variations we are pursuing, and their rationale, both technical and scientific.

  9. Plant species discrimination using emissive thermal infrared imaging spectroscopy

    NASA Astrophysics Data System (ADS)

    Rock, Gilles; Gerhards, Max; Schlerf, Martin; Hecker, Christoph; Udelhoven, Thomas

    2016-12-01

    the signal-to-noise ratio (SNR). At high SNR, the TIR data (Overall Accuracy (OAA) = 92.26%) outperformed the VSWIR data (OAA = 80.28%). This study demonstrates that TIR imaging spectroscopy allows for fast and spatial measurements of spectral plant emissivity with accuracies comparable to laboratory measurement. This innovative technique offers a valuable addition to VSWIR spectroscopy as it provides complimentary information for plant species discrimination.

  10. Soft X-ray emission spectroscopy study of CaF 2(film)/Si(111): non-destructive buried interface analysis

    NASA Astrophysics Data System (ADS)

    Iwami, M.; Kusaka, M.; Hirai, M.; Tagami, R.; Nakamura, H.; Watabe, H.

    1997-06-01

    A soft X-ray emission spectroscopy (SXES) study under an energetic electron irradiation is first applied to a non-destructive buried interface analysis of a CaF 2(film ˜ 40 nm)/Si(111) contact system, where the energy of primary electrons, Ep, is ≤ 5 keV. The present work has explored the usefulness of the application of the SXES method to the interface study to give rise to the following findings: the CaF 2/Si(111) interface shows rather sharp transition from the top CaF 2 to the substrate Si, there certainly is a Ca-silicide layer at the CaF 2/Si(111) interface, the thickness of the silicide layer is estimated to be less than several nm, and the e-beam excited SXES non-destructive study is very powerful to analyze a specimen with rather thick top film (> 40 nm) and thin interface layer (< several nm).

  11. 5 f -Shell correlation effects in dioxides of light actinides studied by O 1s x-ray absorption and emission spectroscopies and first-principles calculations

    NASA Astrophysics Data System (ADS)

    Modin, A.; Suzuki, M.-T.; Vegelius, J.; Yun, Y.; Shuh, D. K.; Werme, L.; Nordgren, J.; Oppeneer, P. M.; Butorin, S. M.

    2015-08-01

    Soft x-ray emission and absorption spectroscopic data are reported for the O 1s region of a single crystal of UO2, a polycrystalline NpO2 sample, and a single crystal of PuO2. The experimental data are interpreted using first-principles correlated-electron calculations within the framework of the density functional theory with added Coulomb U interaction (DFT+U). A detailed analysis regarding the origin of different structures in the x-ray emission and x-ray absorption spectra is given and the effect of varying the intra-atomic Coulomb interaction-U for the 5 f electrons is investigated. Our data indicate that O 1s x-ray absorption and emission spectroscopies can, in combination with DFT+U calculations, successfully be used to study 5 f -shell Coulomb correlation effects in dioxides of light actinides. The values for the Coulomb U parameter in these dioxides are derived to be in the range of 4-5 eV.

  12. Photolysis of n-butyl nitrite and isoamyl nitrite at 355 nm: A time-resolved Fourier transform infrared emission spectroscopy and ab initio study

    SciTech Connect

    Ji Min; Zhen Junfeng; Zhang Qun; Chen Yang

    2009-05-07

    We report on the photodissociation dynamics study of n-butyl nitrite and isoamyl nitrite by means of time-resolved Fourier transform infrared (TR-FTIR) emission spectroscopy. The obtained TR-FTIR emission spectra of the nascent NO fragments produced in the 355 nm laser photolysis of the two alkyl nitrite species showed an almost identical rotational temperature and vibrational distributions of NO. In addition, a close resemblance between the two species was also found in the measured temporal profiles of the IR emission of NO and the recorded UV absorption spectra. The experimental results are consistent with our ab initio calculations using the time-dependent density functional theory at the B3LYP/6-311G(d,p) level, which indicate that the substitution of one of the two {gamma}-H atoms in n-C{sub 4}H{sub 9}ONO with a methyl group to form (CH{sub 3}){sub 2}C{sub 3}H{sub 5}ONO has only a minor effect on the photodissociation dynamics of the two molecules.

  13. Thermal Emission Spectroscopy of Laboratory Regoliths

    NASA Astrophysics Data System (ADS)

    Wagner, C.

    2000-03-01

    The interpretation of emission spectra of planetary objects requires laboratory measurements for comparison. Emissivity measurements carried out at atmospheric pressure give not always a true analogue for the actual spectra of airless planetary objects, but they still provide valuable and practically indispensable results. The present study provides emissivity spectra of ten feldspars in the wavelength range from 6.3 to 17.5 μm, in dependence on the samples' grain size. The grain size is varied in the range from < 25 to 180 μm. Moreover, emissivity spectra are given for several binary mixtures of feldspar and pyroxene. It was found that linear mixing (i.e., linear combination of the component spectra, according to the components' volume percentages) provides a good approximation for the measured mixture spectrum. This was found not only for the wet-sieved coarser grain size fractions, where reflectance and emittance are dominated by surface scattering, but also for the grain size fractions < 63 μm, whose spectra reveal a significant contribution of volume scattering, and where the mixing was therefore expected to be nonlinear.

  14. Site-specific intermolecular interaction in α-phase crystalline films of phthalocyanines studied by soft x-ray emission spectroscopy.

    PubMed

    Yamane, H; Hatsui, T; Iketaki, K; Kaji, T; Hiramoto, M; Kosugi, N

    2011-07-21

    The local electronic structures of crystalline and amorphous films of zinc phthalocyanine (ZnPc) and metal-free phthalocyanine (H(2)Pc) have been studied by soft x-ray emission spectroscopy (XES). We found a clear crystalline structure dependence of the elastic-peak shape in the resonant XES spectra. The elastic peaks of both ZnPc and H(2)Pc are found to show an asymmetric shape due to resonant inelastic x-ray scattering (RIXS) at the nitrogen sites for the α-crystalline films, but not for the amorphous films. The observed RIXS feature is ascribed to the charge transfer excitation due to the Raman-active intermolecular interaction, which dominates the excited-electron dynamics in α-crystalline phthalocyanine films.

  15. Valence Band Density of States of Cu3Si Studied by Soft X-Ray Emission Spectroscopy and a First-Principle Molecular Orbital Calculation

    NASA Astrophysics Data System (ADS)

    An, Zhenlian; Kamezawa, Chihiro; Hirai, Masaaki; Kusaka, Masahiko; Iwami, Motohiro

    2002-12-01

    A systematic study of the valence band structure of Cu3Si has been performed by soft X-ray emission spectroscopy and a first-principle molecular orbital calculation using the discrete-variational (DV)-Xα cluster model. The existence of Cu 4s, 4p states in the valence band and their important contributions to the valence band as that of Cu 3d are indicated together with previously reported ones. The high-binding energy peak in the Si L2,3 emission spectrum is considered to originate mainly from the Si-Si 3s bonding state but also have a certain contribution of Si 3s bonding state with Cu 4s, 4p. On the other hand, the low-binding energy peaks in the Si L2,3 emission band are attributed to both the antibonding states of Si 3s and the bonding states of Si 3d with Cu 4s, 4p and Cu 3d. The bonding states of Si 3s with Cu 4s, 4p and Cu 3d are expected to exist in the lower part of the valence band for η\\prime-Cu3Si on the basis of the theoretical calculations. As for Si p states, the high-binding energy peak and the low-binding energy peak in the Si Kβ emission spectrum should be attributed to the Si 3p bonding state and antibonding state with Cu 3d and Cu 4s, 4p, respectively, according to the theoretical calculations. A comparison is made between experimental spectra and theoretical density of states.

  16. Absorption/emission spectroscopy and applications using shock tubes

    NASA Astrophysics Data System (ADS)

    Sulzmann, K. G. P.

    1988-09-01

    A historical overview is presented about the important contributions made by Penner, his co-workers, and his students to the application of shock-tube techniques for quantitative emission and absorption spectroscopy and its applications to chemical kinetics studies in high-temperature gases. The discussions address critical aspects related to valid determinations of quantitative spectroscopic data and chemical rate parameters and stress the requirements for uniformly heated gas samples, temperature determinations, gas-mixture preparations, selection of useful spectral intervals, verification of LTE conditions, time resolutions for concentration histories, uniqueness of kinetic measurements, as well as accuracies and reproducibilities of measurement results.The potential of absorption spectroscopy by molecule and/or radical resonance radiation and by laser transmission techniques is highlighted for kinetic studies in mixtures with very small reactant concentrations.Besides the work by the honoree and his school, the references include books, monographs and key articles related to the subjects discussed.

  17. A CAVITY RINGDOWN SPECTROSCOPY MERCURY CONTINUOUS EMISSION MONITOR

    SciTech Connect

    Christopher C. Carter, Ph.D.

    2002-01-01

    The first quarter of this project to develop a Cavity Ringdown Spectroscopy mercury continuous emission monitor involved acquisition and verification of the laser system to be used, initial cavity design, and initial software development for signal processing and data acquisition.

  18. Liquid-Arc/Spark-Excitation Atomic-Emission Spectroscopy

    NASA Technical Reports Server (NTRS)

    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.

  19. Fluorescence-excitation and Emission Spectroscopy on Single FMO Complexes

    PubMed Central

    Löhner, Alexander; Ashraf , Khuram; Cogdell, Richard J.; Köhler, Jürgen

    2016-01-01

    In green-sulfur bacteria sunlight is absorbed by antenna structures termed chlorosomes, and transferred to the RC via the Fenna-Matthews-Olson (FMO) complex. FMO consists of three monomers arranged in C3 symmetry where each monomer accommodates eight Bacteriochlorophyll a (BChl a) molecules. It was the first pigment-protein complex for which the structure has been determined with high resolution and since then this complex has been the subject of numerous studies both experimentally and theoretically. Here we report about fluorescence-excitation spectroscopy as well as emission spectroscopy from individual FMO complexes at low temperatures. The individual FMO complexes are subjected to very fast spectral fluctuations smearing out any possible different information from the ensemble data that were recorded under the same experimental conditions. In other words, on the time scales that are experimentally accessible by single-molecule techniques, the FMO complex exhibits ergodic behaviour. PMID:27545197

  20. Emission Spectroscopy of the Super-Earth 55 Cnc e

    NASA Astrophysics Data System (ADS)

    Dragomir, Diana; Bean, Jacob; Kreidberg, Laura; Stevenson, Kevin B.; Line, Michael R.

    2017-01-01

    Recent surveys have revealed an extraordinary and unexplained diversity of low-mass exoplanets. The main frontier for constraining the nature and origins of these planets is atmospheric characterization to reveal their detailed physical properties. Previous spectroscopic observations of small exoplanets have been focused on transmission measurements, but these studies are often limited by clouds. We are turning small exoplanet characterization in a new direction with multi-wavelength observations (Warm Spitzer and HST WFC3) of the dayside of 55 Cnc e, a quintessential super-Earth in a tight orbit and transiting a nearby star. We will present the first dayside emission spectrum of a super-Earth, which we use to distinguish between different atmospheric compositions and constrain the vertical temperature structure of the atmosphere. Our results for 55 Cnc e will guide JWST emission spectroscopy of a much larger sample of small close-in transiting exoplanets.

  1. Local optical emission spectroscopy of excited species effused from an evaporation cell and a sputter source into dense plasmas - Basic studies for the deposition of thin gradient films.

    PubMed

    Bolt, H; Hemel, V; Koch, F; Nickel, H

    1996-06-01

    Space resolved optical emission spectroscopy has been applied to determine the distribution of excited species in dense plasmas which are used for the deposition of thin coatings. Typical electron densities and electron temperatures in the plasma facility PETRA ( Plasma Engineering and Technology Research Assembly) are in the range of n(e) = 10(12) cm(-3) and T(e) = 10 eV. During the deposition process material (Al) is evaporated from a vapour cell under controlled conditions. The vapour stream is guided into a dense plasma which is composed of inert gas, Ar or He, and hydrocarbon species produced from the dissociation of C(2)H(2). The evaporated Al-stream which travels with thermal velocity into a plasma of high electron density, is nearly completely ionized due to the short mean free path for electron impact ionization in the above mentioned parameter range. Optical emission spectroscopy has been applied to investigate the interaction processes between the vapour stream and the plasma as well as the transport of the ionized Al along the applied magnetic field. For the measurements space resolved optical emission spectroscopy with an in-situ translation mechanism of the optical fibre has been used to measure the local concentrations of excited Al neutrals and ions as well as the concentration of the background plasma species.

  2. Cobalt Kβ valence-to-core X-ray emission spectroscopy: a study of low-spin octahedral cobalt(iii) complexes.

    PubMed

    Schwalenstocker, Katarina; Paudel, Jaya; Kohn, Alexander W; Dong, Chao; Van Heuvelen, Katherine M; Farquhar, Erik R; Li, Feifei

    2016-09-28

    Kβ valence-to-core (V2C) X-emission spectroscopy (XES) has gained prominence as a tool for molecular inorganic chemists to probe the occupied valence orbitals of coordination complexes, as illustrated by recent evaluation of Kβ V2C XES ranging from titanium to iron. However, cobalt Kβ V2C XES has not been studied in detail, limiting the application of this technique to probe cobalt coordination in molecular catalysts and bioinorganic systems. In addition, the community still lacks a complete understanding of all factors that dictate the V2C peak area. In this manuscript, we report experimental cobalt Kβ V2C XES spectra of low-spin octahedral Co(iii) complexes with different ligand donors, in conjunction with DFT calculations. Cobalt Kβ V2C XES was demonstrated to be sensitive to cobalt-ligand coordination environments. Notably, we recognize here for the first time that there is a linear correlation between the V2C area and the spectrochemical series for low-spin octahedral cobalt(iii) complexes, with strong field π acceptor ligands giving rise to the largest V2C area. This unprecedented correlation is explained by invoking different levels of π-interaction between cobalt p orbitals and ligand orbitals that modulate the percentage of cobalt p orbital character in donor MOs, in combination with changes in the average cobalt-ligand distance.

  3. Electronic structure of KD2xH2(1-x)PO4 studied by soft x-ray absorption and emission spectroscopies

    SciTech Connect

    Kucheyev, S O; Bostedt, C F; van Buuren, T; Willey, T M; Land, T A; Terminello, L J; Felter, T E; Hamza, A V; Demos, S G; Nelson, A J

    2004-04-27

    The surface and bulk electronic structure of tetragonal (at 300 K) and orthorhombic (at 77 K) KD{sub 2x}H{sub 2(1-x)}PO{sub 4} single crystals (so-called KDP and DKDP), with a deuteration degree x of 0.0, 0.3, and 0.6, is studied by soft x-ray absorption near-edge structure (XANES) and non-resonant soft x-ray emission (XES) spectroscopies. High-resolution O K-edge, P L{sub 2,3}-edge, and K L{sub 2,3}-edge XANES and XES spectra reveal that the element-specific partial density of states in the conduction and valence bands is essentially independent of deuteration x. We give assignment of XANES and XES peaks based on previous molecular orbital and band-structure calculations. Projected densities of states in the conduction band also appear to be essentially identical for tetragonal (at 300 K) and orthorhombic (at 77 K) phases, consistent with previous band structure calculations. However, a decrease in sample temperature from 300 to 77 K results in an {approx} 0.5 eV shift in the valence band edge (probed by XES), with negligible changes to the conduction band edge (probed by XANES). Results also show that high-intensity x-ray irradiation results in decomposition of these hydrogen-bonded materials into water and KPO{sub 3} cyclo- and polyphosphates.

  4. Absolute and relative emission spectroscopy study of 3 cm wide planar radio frequency atmospheric pressure bio-plasma source

    SciTech Connect

    Deng, Xiaolong; Nikiforov, Anton Yu Leys, Christophe; Ionita, Eusebiu-Rosini; Dinescu, Gheorghe

    2015-08-03

    The dynamics of low power atmospheric pressure radio frequency discharge generated in Ar gas in long gap of 3 cm is investigated. This plasma source is characterized and analyzed for possible large scale biomedical applications where low gas temperature and potential-less effluent are required. The discharge forms a homogenous glow-like afterglow in ambient air at input power of 30 W with low gas temperature of 330 K, which is desirable in biomedical applications. With absolute calibrated spectroscopy of the discharge, electron density of 0.4 × 10{sup 18} m{sup −3} and electron temperature of 1.5 eV are obtained from continuum Bremsstrahlung radiation of the source. Time and spatial resolved emission spectroscopy is used to analyze discharge generation mechanism and active species formation. It is found that discharge dynamics strongly correlates with the discharge current waveform. Strong Ar(2p) excited states emission is observed nearby the electrodes surface on a distance up to 200 μm in the plasma sheath region at 10 ns after the current peak, whereas OH(A) emission is uniform along of the interelectrode gap.

  5. [Spectroscopy technique and ruminant methane emissions accurate inspecting].

    PubMed

    Shang, Zhan-Huan; Guo, Xu-Sheng; Long, Rui-Jun

    2009-03-01

    The increase in atmospheric CH4 concentration, on the one hand through the radiation process, will directly cause climate change, and on the other hand, cause a lot of changes in atmospheric chemical processes, indirectly causing climate change. The rapid growth of atmospheric methane has gained attention of governments and scientists. All countries in the world now deal with global climate change as an important task of reducing emissions of greenhouse gases, but the need for monitoring the concentration of methane gas, in particular precision monitoring, can be scientifically formulated to provide a scientific basis for emission reduction measures. So far, CH4 gas emissions of different animal production systems have received extensive research. The methane emission by ruminant reported in the literature is only estimation. This is due to the various factors that affect the methane production in ruminant, there are various variables associated with the techniques for measuring methane production, the techniques currently developed to measure methane are unable to accurately determine the dynamics of methane emission by ruminant, and therefore there is an urgent need to develop an accurate method for this purpose. Currently, spectroscopy technique has been used and is relatively a more accurate and reliable method. Various spectroscopy techniques such as modified infrared spectroscopy methane measuring system, laser and near-infrared sensory system are able to achieve the objective of determining the dynamic methane emission by both domestic and grazing ruminant. Therefore spectroscopy technique is an important methane measuring technique, and contributes to proposing reduction methods of methane.

  6. Fourier spectroscopy of the stratospheric emission

    NASA Technical Reports Server (NTRS)

    Carli, B.; Mencaraglia, F.; Bonetti, A.

    1980-01-01

    Stratospheric emission spectra in the submillimeter range have been recorded with a resolution of 0.0033/cm with a balloon-borne interferometer. Several minor atmospheric constituents have been identified in a preliminary analysis of the spectra; these are water vapor, oxygen, ozone isotopes, nitric acid, nitrous oxide, hydrofluoric and hydrochloric acids, and carbon monoxide.

  7. Plasma emission spectroscopy method of tumor therapy

    DOEpatents

    Fleming, K.J.

    1997-03-11

    Disclosed are a method and apparatus for performing photon diagnostics using a portable and durable apparatus which incorporates the use of a remote sensing probe in fiberoptic communication with an interferometer or spectrometer. Also disclosed are applications for the apparatus including optically measuring high velocities and analyzing plasma/emission spectral characteristics. 6 figs.

  8. Plasma emission spectroscopy method of tumor therapy

    DOEpatents

    Fleming, Kevin J.

    1997-01-01

    Disclosed are a method and apparatus for performing photon diagnostics using a portable and durable apparatus which incorporates the use of a remote sensing probe in fiberoptic communication with an interferometer or spectrometer. Also disclosed are applications for the apparatus including optically measuring high velocities and analyzing plasma/emission spectral characteristics.

  9. LASER ABLATION-INDUCTIVELY COUPLED PLASMA-ATOMIC EMISSION SPECTROSCOPY STUDY AT THE 222-S LABORATORY USING HOT-CELL GLOVE BOX PROTOTYPE SYSTEM

    SciTech Connect

    LOCKREM LL; OWENS JW; SEIDEL CM

    2009-03-26

    This report describes the installation, testing and acceptance of the Waste Treatment and Immobilization Plant procured laser ablation-inductively coupled plasma-atomic emission spectroscopy (LA-ICP-AES) system for remotely analyzing high-level waste samples in a hot cell environment. The 2005-003; ATS MP 1027, Management Plan for Waste Treatment Plant Project Work Performed by Analytical Technical Services. The APD group at the 222-S laboratory demonstrated acceptable turnaround time (TAT) and provide sufficient data to assess sensitivity, accuracy, and precision of the LA-ICP-AES method.

  10. LASER ABLATION-INDUCTIVELY COUPLED PLASMA-ATOMIC EMISSION SPECTROSCOPY STUDY AT THE 222-S LABORATORY USING HOT-CELL GLOVE BOX PROTOTYPE SYSTEM

    SciTech Connect

    SEIDEL CM; JAIN J; OWENS JW

    2009-02-23

    This report describes the installation, testing, and acceptance of the Waste Treatment and Immobilization Plant (WTP) procured laser ablation-inductively coupled plasma-atomic emission spectroscopy (LA-ICP-AES) system for remotely analyzing high-level waste (HLW) samples in a hot cell environment. The work was completed by the Analytical Process Development (APD) group in accordance with Task Order 2005-003; ATS MP 1027, Management Plan for Waste Treatment Plant Project Work Performed by Analytical Technical Services. The APD group at the 222-S Laboratory demonstrated acceptable turnaround time (TAT) and provide sufficient data to assess sensitivity, accuracy, and precision of the LA-ICP-AES method.

  11. Controlled variation of the information depth by angle dependent soft X-ray emission spectroscopy: A study on polycrystalline Cu(In,Ga)Se 2

    NASA Astrophysics Data System (ADS)

    Mönig, H.; Lauermann, I.; Grimm, A.; Camus, C.; Kaufmann, C. A.; Pistor, P.; Jung, Ch.; Kropp, T.; Lux-Steiner, M. C.; Fischer, Ch.-H.

    2008-12-01

    Angle dependent X-ray emission spectroscopy (AXES) is introduced as a tool for depth dependent composition analysis. A controlled variation of the information depth is demonstrated by changing the geometry from grazing exit to grazing incidence geometry. First results are presented from Cu(In,Ga)Se 2 (CIGSe)-based polycrystalline thin film solar cell bi-layer components. A mathematical model explains changes in relative intensity due to the absorption and emission behavior of thin CdS and Zn(S,O) cover layers. The fact that the presented data can be modelled by ideal bi-layer structures, provides both, proof of concept in general and the proof of applicability to the relatively rough layered structures based on CIGSe. In bare CIGSe a homogeneous distribution of Cu and Ga is found in a depth range between 22 and 470 nm.

  12. Emission spectroscopy analysis during Nopal cladodes dethorning by laser ablation

    NASA Astrophysics Data System (ADS)

    Peña-Díaz, M.; Ponce, L.; Arronte, M.; Flores, T.

    2007-04-01

    Optical emission spectroscopy of the pulsed laser ablation of spines and glochids from Opuntia (Nopal) cladodes was performed. Nopal cladodes were irradiated with Nd:YAG free-running laser pulses on their body, glochids and spines. Emission spectroscopy analyses in the 350-1000 nm region of the laser induced plasma were made. Plasma plume evolution characterization, theoretical calculations of plasma plume temperature and experiments varying the processing atmosphere showed that the process is dominated by a thermally activated combustion reaction which increases the dethorning process efficiency. Therefore, appropriate laser pulse energy for minimal damage of cladodes body and in the area beneath glochids and spines can be obtained.

  13. Steelmaking process control using remote ultraviolet atomic emission spectroscopy

    NASA Astrophysics Data System (ADS)

    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.

  14. Electronic structure of Al-doped ZnO transparent conductive thin films studied by x-ray absorption and emission spectroscopies

    SciTech Connect

    Huang, W. H.; Sun, S. J.; Chiou, J. W.; Chou, H.; Chan, T. S.; Lin, H.-J.; Kumar, Krishna; Guo, J.-H.

    2011-11-15

    This study used O K-, Zn L{sub 3}-, Zn K-, and Al K-edges x-ray absorption near-edge structure (XANES) and O K-edge x-ray emission spectroscopy (XES) measurements to investigate the electronic structure of transparent Al-doped ZnO (AZO) thin film conductors. The samples were prepared on glass substrates at a low temperature near 77 K by using a standard RF sputtering method. High-purity Ne (5N) was used as the sputtering gas. The crystallography of AZO thin films gradually transformed from the ZnO wurtize structure to an amorphous structure during sample deposition, which suggests the suitability to grow on flexible substrates, eliminating the severe degradation due to fragmentation by repeated bending. The O K- and Zn L{sub 3}-edges XANES spectra of AZO thin films revealed a decrease in the number of both O 2p and Zn 3d unoccupied states when the pressure of Ne was increased from 5 to 100 mTorr. In contrast, Al K-edges XANES spectra showed that the number of unoccupied states of Al 3p increased in conjunction with the pressure of Ne, indicating an electron transfer from Al to O atoms, and suggesting that Al doping increases the negative effective charge of oxygen ions. XES and XANES spectra of O 2p states at the O K-edge also revealed that Al doping not only raised the conduction-band-minimum, but also increased the valence-band-maximum and the band-gap. The results indicate that the reduction in conductivity of AZO thin films is due to the generation of ionic characters, the increase in band-gap, and the decrease in density of unoccupied states of oxygen.

  15. Thermal emission spectroscopy of the middle atmosphere

    NASA Technical Reports Server (NTRS)

    Kunde, V. G.; Brasunas, J. C.; Conrath, B. J.; Herman, J. R.; Maguire, W. C.; Massie, S. T.; Abbas, Mian M.

    1990-01-01

    The general objective of this research is to obtain, via remote sensing, simultaneous measurements of the vertical distributions of stratospheric temperature, ozone, and trace constituents that participate in the catalytic destruction of ozone (NO(sub y): NO, NO2, NO3, HNO3, ClONO2, N2O5, HNO4; Cl(sub x): HOCl), and the source gases for the catalytic cycles (H2O, CH4, N2O, CF2Cl2, CFCl3, CCl4, CH3Cl, CHF2Cl, etc.). Data are collected during a complete diurnal cycle in order to test our present understanding of ozone chemistry and its associate catalytic cycles. The instrumentation employed is an emission-mode, balloon-borne, liquid-nitrogen-cooled Michelson interferometer-spectrometer (SIRIS), covering the mid-infrared range with a spectral resolution of 0.020 cm(exp -1). Cryogenic cooling combined with the use of extrinsic silicon photoconductor detectors allows the detection of weak emission features of stratospheric gaseous species. Vertical distributions of these species are inferred from scans of the thermal emission of the limb in a sequence of elevation angles. The fourth SIRIS balloon flight was carried out from Palestine, Texas on September 15-16, 1986 with 9 hours of nighttime data (40 km). High quality data with spectral resolution 0.022 cm(exp -1), were obtained for numerous limb sequences. Fifteen stratospheric species have been identified to date from this flight: five species from the NO(sub y) family (HNO3, NO2, NO, ClONO2, N2O5), plus CO2, O3, H2O, N2O, CH4, CCl3F, CCl2F2, CHF2Cl, CF4, and CCl4. The nighttime values of N2O5, ClONO2, and total odd nitrogen have been measured for the first time, and compared to model results. Analysis of the diurnal variation of N2O5 within the 1984 and 1986 data sets, and of the 1984 ClONO2 measurements, were presented in the literature. The demonstrated ability of SIRIS to measure all the major NO(sub y) species, and therefore to determine the partitioning of the nitrogen family over a continuous diurnal cycle, is

  16. Absorption and Emission Spectroscopy of a Lasing Material: Ruby

    ERIC Educational Resources Information Center

    Esposti, C. Degli; Bizzocchi, L.

    2007-01-01

    Ruby is a crystalline material, which comes very expensive and is of great significance, as it helped in the creation of first laser. An experiment to determine the absorption and emission spectroscopy, in addition to the determination of the room-temperature lifetime of the substance is being described.

  17. Theory of single molecule emission spectroscopy

    SciTech Connect

    Bel, Golan; Brown, Frank L. H.

    2015-05-07

    A general theory and calculation framework for the prediction of frequency-resolved single molecule photon counting statistics is presented. Expressions for the generating function of photon counts are derived, both for the case of naive “detection” based solely on photon emission from the molecule and also for experimentally realizable detection of emitted photons, and are used to explicitly calculate low-order photon-counting moments. The two cases of naive detection versus physical detection are compared to one another and it is demonstrated that the physical detection scheme resolves certain inconsistencies predicted via the naive detection approach. Applications to two different models for molecular dynamics are considered: a simple two-level system and a two-level absorber subject to spectral diffusion.

  18. Diamond Analyzed by Secondary Electron Emission Spectroscopy

    NASA Technical Reports Server (NTRS)

    Krainsky, Isay L.

    1998-01-01

    Diamond is a promising semiconductor material for novel electronic applications because of its chemical stability and inertness, heat conduction properties, and so-called negative electron affinity (NEA). When a surface has NEA, electrons generated inside the bulk of the material are able to come out into the vacuum without any potential barrier (work function). Such a material would have an extremely high secondary electron emission coefficient o, very high photoelectron (quantum) yield, and would probably be an efficient field emitter. Chemical-vapor-deposited (CVD) polycrystalline diamond films have even more advantages than diamond single crystals. Their fabrication is relatively easy and inexpensive, and they can be grown with high levels of doping--consequently, they can have relatively high conductivity. Because of these properties, diamond can be used for cold cathodes and photocathodes in high-power electronics and in high-frequency and high-temperature semiconductor devices.

  19. Absolute Emission Spectroscopy of Electronically Excited Products of Dissociative Recombination

    NASA Astrophysics Data System (ADS)

    Skrzypkowski, M. P.; Gougousi, T.; Golde, M. F.; Johnsen, R.

    1997-10-01

    We have employed spatially-resolved optical emission spectroscopy in a flowing afterglow plasma to investigate radiations in the 200-400 nm range resulting from electron-ion dissociative recombination. Calibrated emission data combined with Langmuir probe electron-density measurements are analyzed to obtain branching ratios for electronically excited recombination products. In particular, we will report absolute yields of CO(a^3Π) resulting from recombining CO_2^+ ions, NO(B^2Π) from N_2O^+, OH(A^2Σ^+) from HCO_2^+, as well as NH(A^3Π_i), and OH(A^2Σ^+) from the recombination of N_2OH^+ ions.

  20. Current Problems in X-Ray Emission Spectroscopy

    NASA Technical Reports Server (NTRS)

    Goldstein, Joseph I.; Williams, David B.; Lyman, Charles E.

    1989-01-01

    Various problems that limit X-ray analysis in the analytical electron microscope are reviewed. Major emphasis is given to the trade-off between minimum mass fraction and spatial resolution. New developments such as high-brightness electron guns, new X-ray spectrometers and clean high-vacuum analysis conditions will lead to major improvements in the accuracy and detectability limits of X-ray emission spectroscopy.

  1. Compensation and trapping in CdZnTe radiation detectors studied by thermoelectric emission spectroscopy, thermally stimulated conductivity, and current-voltage measurements

    SciTech Connect

    Ralph B. James

    2000-01-07

    In today's commercially available counter-select-grade CdZnTe crystals for radiation detector applications, the thermal ionization energies of the traps and their types, whether electron or hole traps, were measured. The measurements were successfully done using thermoelectric emission spectroscopy (TEES) and thermally stimulated conductivity (TSC). For reliability, the electrical contacts to the sample were found to be very important and, instead of Au Schottky contacts, In Ohmic contacts had to be used. For the filling of the traps, photoexcitation was done at zero bias, at 20K and at wavelengths which gave the maximum bulk photoexcitation for the sample. Between the temperature range from 20 to 400 K, the TSC current was found to be on the order of {approximately} 10,000 times or even larger than the TEES current, in agreement with theory, but only TEES could resolve the trap type and was sensitive to the deep traps. Large concentration of hole traps at 0.1 and 0.6 eV were observed and smaller contraction of electron traps at 0.4 eV was seen. These deep traps cause compensation in the material and also cause trapping that degrades the radiation detection measurement.

  2. Excited state structural events of a dual-emission fluorescent protein biosensor for Ca²⁺ imaging studied by femtosecond stimulated Raman spectroscopy.

    PubMed

    Wang, Yanli; Tang, Longteng; Liu, Weimin; Zhao, Yongxin; Oscar, Breland G; Campbell, Robert E; Fang, Chong

    2015-02-12

    Fluorescent proteins (FPs) are luminescent biomolecules that emit characteristic hues upon irradiation. A group of calmodulin (CaM)-green FP (GFP) chimeras have been previously engineered to enable the optical detection of calcium ions (Ca(2+)). We investigate one of these genetically encoded Ca(2+) biosensors for optical imaging (GECOs), GEM-GECO1, which fluoresces green without Ca(2+) but blue with Ca(2+), using femtosecond stimulated Raman spectroscopy (FSRS). The time-resolved FSRS data (<800 cm(-1)) reveal that initial structural evolution following 400 nm photoexcitation involves small-scale coherent proton motions on both ends of the chromophore two-ring system with a <250 fs time constant. Upon Ca(2+) binding, the chromophore adopts a more twisted conformation in the protein pocket with increased hydrophobicity, which inhibits excited-state proton transfer (ESPT) by effectively trapping the protonated chromophore in S1. Both the chromophore photoacidity and local environment form the ultrafast structural dynamics basis for the dual-emission properties of GEM-GECO1. Its photochemical transformations along multidimensional reaction coordinates are evinced by distinct stages of FSRS spectral evolution, particularly related to the ∼460 and 504 cm(-1) modes. The direct observation of lower frequency modes provides crucial information about the nuclear motions preceding ESPT, which enriches our understanding of photochemistry and enables the rational design of new biosensors.

  3. Diffusive and inelastic scattering in ballistic-electron-emission spectroscopy and ballistic-electron-emission microscopy

    SciTech Connect

    Lee, E.Y.; Turner, B.R.; Schowalter, L.J.

    1993-07-01

    Ballistic-electron-emission microscopy (BEEM) of Au/Si(001) n type was done to study whether elastic scattering in the Au overlayer is dominant. It was found that there is no dependence of the BEEM current on the relative gradient of the Au surface with respect to the Si interface, and this demonstrates that significant elastic scattering must occur in the Au overlayer. Ballistic-electron-emission spectroscopy (BEES) was also done, and, rather than using the conventional direct-current BEES, alternating-current (ac) BEES was done on Au/Si and also on Au/PtSi/Si(001) n type. The technique of ac BEES was found to give linear threshold for the Schottky barrier, and it also clearly showed the onset of electron-hole pair creation and other inelastic scattering events. The study of device quality PtSi in Au/PtSi/Si(001) yielded an attenuation length of 4 nm for electrons of energy 1 eV above the PtSi Fermi energy. 20 refs., 5 figs.

  4. Ultrafast Time-Resolved Emission and Absorption Spectra of meso-Pyridyl Porphyrins upon Soret Band Excitation Studied by Fluorescence Up-Conversion and Transient Absorption Spectroscopy.

    PubMed

    Venkatesh, Yeduru; Venkatesan, M; Ramakrishna, B; Bangal, Prakriti Ranjan

    2016-09-08

    A comprehensive study of ultrafast molecular relaxation processes of isomeric meso-(pyridyl) porphyrins (TpyPs) has been carried out by using femtosecond time-resolved emission and absorption spectroscopic techniques upon pumping at 400 nm, Soret band (B band or S2), in 4:1 dichloromethane (DCM) and tetrahydrofuran (THF) solvent mixture. By combined studies of fluorescence up-conversion, time-correlated single photon counting, and transient absorption spectroscopic techniques, a complete model with different microscopic rate constants associated with elementary processes involved in electronic manifolds has been reported. Besides, a distinct coherent nuclear wave packet motion in Qy state is observed at low-frequency mode, ca. 26 cm(-1) region. Fluorescence up-conversion studies constitute ultrafast time-resolved emission spectra (TRES) over the whole emission range (430-710 nm) starting from S2 state to Qx state via Qy state. Careful analysis of time profiles of up-converted signals at different emission wavelengths helps to reveal detail molecular dynamics. The observed lifetimes are as indicated: A very fast decay component with 80 ± 20 fs observed at ∼435 nm is assigned to the lifetime of S2 (B) state, whereas being a rise component in the region of between 550 and 710 nm emission wavelength pertaining to Qy and Qx states, it is attributed to very fast internal conversion (IC) occurring from B → Qy and B → Qx as well. Two distinct components of Qy emission decay with ∼200-300 fs and ∼1-1.5 ps time constants are due to intramolecular vibrational redistribution (IVR) induced by solute-solvent inelastic collisions and vibrational redistribution induced by solute-solvent elastic collision, respectively. The weighted average of these two decay components is assigned as the characteristic lifetime of Qy, and it ranges between 0.3 and 0.5 ps. An additional ∼20 ± 2 ps rise component is observed in Qx emission, and it is assigned to the formation time of

  5. Refining mid-infrared emission spectroscopy as a tool for understanding planetary surface mineralogy through laboratory studies, computational models, and lunar remote sensing data

    NASA Astrophysics Data System (ADS)

    Arnold, Jessica Anne

    Mid-infrared emissivity spectra, while useful for quantifying mineral abundance, are dependent on a variety of other factors, including grain size. At present, scattering models are not fully able reproduce this dependence, especially for very fine-grained powders (d˜<60μm) typical of planetary regolith. Previous studies have modeled emissivity spectra of mineral powders by using Mie single scattering theory coupled with a radiative transfer model, such as Hapke [1993]. Chapter 2 of this work uses multiple scattering T-matrix code (from Mackowski and Mishchenko, 2011) to calculate the scattering coefficients for a cluster of spheres, rather than a single sphere as in Mie theory. I acquired emissivity spectra of highly uniform silica glass spheres, normally used for sieve calibration, for comparison to modeled spectra. Then, I calculated optical constants of the glass from micro-FTIR reflectance spectra of polished grains mounted on a petrographic slide. Modeled emissivity spectra computed with this T-matrix/radiative transfer hybrid method show a marked improvement over Mie-radiative transfer hybrid models, especially for smaller grain sizes. The complex index of refraction (n=n+i k) as a function of wavelength, where n and k are often referred to as optical constants, is an essential input into radiative transfer models. Hence, quantitative estimates of mineral abundance from remote sensing data require that optical constants are known for a comprehensive set of relevant minerals. While many geologically abundant materials are monoclinic or triclinic, due to both the additional complexity of the models needed and the increased effort required to orient these samples, very few sets of optical constants have been measured for lower-symmetry minerals. Chapter 3 describes how optical constants were calculated from polarized mid-infrared reflectance spectra of oriented single-crystals of five natural samples in the monoclinic crystal system, which include four

  6. Atomic Absorption Spectroscopy, Atomic Emission Spectroscopy, and Inductively Coupled Plasma-Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Miller, Dennis D.; Rutzke, Michael A.

    Atomic spectroscopy has played a major role in the development of our current database for mineral nutrients and toxicants in foods. When atomic absorption spectrometers became widely available in the 1960s, the development of atomic absorption spectroscopy (AAS) methods for accurately measuring trace amounts of mineral elements in biological samples paved the way for unprecedented advances in fields as diverse as food analysis, nutrition, biochemistry, and toxicology (1). The application of plasmas as excitation sources for atomic emission spectroscopy (AES) led to the commercial availability of instruments for inductively coupled plasma - atomic emission spectroscopy (ICP-AES) beginning in the late 1970s. This instrument has further enhanced our ability to measure the mineral composition of foods and other materials rapidly, accurately, and precisely. More recently, plasmas have been joined with mass spectrometers (MS) to form inductively coupled plasma-mass spectrometer ICP-MS instruments that are capable of measuring mineral elements with extremely low detection limits. These three instrumental methods have largely replaced traditional wet chemistry methods for mineral analysis of foods, although traditional methods for calcium, chloride, iron, and phosphorus remain in use today (see Chap. 12).

  7. Gas emission analysis based on Fourier transformed infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Shu, Xiaowen; Zhang, Xiaofu; Lian, Xu; Jin, Hui

    2014-12-01

    Solar occultation flux (SOF), a new optical technology to detect the gas based on the traditional Fourier transformed infrared spectroscopy (FTIR) developed quickly recently. In this paper, the system and the data analysis is investigated. First a multilayer transmission model of solar radiation is simulated. Then the retrieval process is illustrated. In the proceeding of the data analysis, the Levenberg-Marquardt non-linear square fitting is used to obtain the gas column concentration and the related emission ratio. After the theory certification, the built up system is conducted in a fertilizer plant in Hefei city .The results show SOF is available in the practice and the retrieved gas column concentration can give important information about the pollution emission and dispersion

  8. Quantitative compositional analysis of sedimentary materials using thermal emission spectroscopy: 1. Application to sedimentary rocks

    NASA Astrophysics Data System (ADS)

    Thorpe, Michael T.; Rogers, A. Deanne; Bristow, Thomas F.; Pan, Cong

    2015-11-01

    Thermal emission spectroscopy is used to determine the mineralogy of sandstone and mudstone rocks as part of an investigation of linear spectral mixing between sedimentary constituent phases. With widespread occurrences of sedimentary rocks on the surface of Mars, critical examination of the accuracy associated with quantitative models of mineral abundances derived from thermal emission spectra of sedimentary materials is necessary. Although thermal emission spectroscopy has been previously proven to be a viable technique to obtain quantitative mineralogy from igneous and metamorphic materials, sedimentary rocks, with natural variation of composition, compaction, and grain size, have yet to be examined. In this work, we present an analysis of the thermal emission spectral (~270-1650 cm-1) characteristics of a suite of 13 sandstones and 14 mudstones. X-ray diffraction and traditional point counting procedures were all evaluated in comparison with thermal emission spectroscopy. Results from this work are consistent with previous thermal emission spectroscopy studies and indicate that bulk rock mineral abundances can be estimated within 11.2% for detrital grains (i.e., quartz and feldspars) and 14.8% for all other mineral phases present in both sandstones and mudstones, in comparison to common in situ techniques used for determining bulk rock composition. Clay-sized to fine silt-sized grained phase identification is less accurate, with differences from the known ranging from ~5 to 24% on average. Nevertheless, linear least squares modeling of thermal emission spectra is an advantageous technique for determining abundances of detrital grains and sedimentary matrix and for providing a rapid classification of clastic rocks.

  9. BATMAN beam properties characterization by the beam emission spectroscopy diagnostic

    SciTech Connect

    Bonomo, F.; Ruf, B.; Schiesko, L.; Fantz, U.; Franzen, P.; Riedl, R.; Wünderlich, D.; Barbisan, M.; Pasqualotto, R.; Serianni, G.; Cristofaro, S.

    2015-04-08

    The ITER neutral beam heating systems are based on the production and acceleration of negative ions (H/D) up to 1 MV. The requirements for the beam properties are strict: a low core beam divergence (< 0.4 °) together with a low source pressure (≤ 0.3 Pa) would permit to reduce the ion losses along the beamline, keeping the stripping particle losses below 30%. However, the attainment of such beam properties is not straightforward. At IPP, the negative ion source testbed BATMAN (BAvarian Test MAchine for Negative ions) allows for deepening the knowledge of the determination of the beam properties. One of the diagnostics routinely used to this purpose is the Beam Emission Spectroscopy (BES): the H{sub α} light emitted in the beam is detected and the corresponding spectra are evaluated to estimate the beam divergence and the stripping losses. The BES number of lines of sight in BATMAN has been recently increased: five horizontal lines of sight providing a vertical profile of the beam permit to characterize the negative ion beam properties in relation to the source parameters. Different methods of H{sub α} spectra analysis are here taken into account and compared for the estimation of the beam divergence and the amount of stripping. In particular, to thoroughly study the effect of the space charge compensation on the beam divergence, an additional hydrogen injection line has been added in the tank, which allows for setting different background pressure values (one order of magnitude, from about 0.04 Pa up to the source pressure) in the beam drift region.

  10. Comparing Compositions of Modern Cast Bronze Sculptures: Optical Emission Spectroscopy Versus x-Ray Fluorescence Spectroscopy

    NASA Astrophysics Data System (ADS)

    Young, M. L.; Dunand, D. C.

    2015-07-01

    Bulk elemental compositions of 74 modern cast bronze sculptures from the collection at the Art Institute of Chicago, the Philadelphia Museum of Art, and the Rodin Museum (Philadelphia, PA) were determined using inductively coupled plasma-optical emission spectroscopy (ICP-OES) and a handheld x-ray fluorescence (XRF) spectrometer. The elemental compositions of the cast sculptures as measured previously by ICP-OES and presently by XRF are compared: A good match is found between the two methods for the base metal (Cu) and the two majority alloying elements (Zn and Sn). For both ICP-OES and XRF data, when the Zn composition is plotted versus the Sn composition, three discernable clusters are found that are related to the artist, foundry, casting date, and casting method; they consist of (A) high-zinc brass, (B) low-zinc, low-tin brass, and (C) low-zinc, tin bronze. Thus, our study confirms that the relatively fast, nondestructive XRF spectrometry can be used effectively over slower and invasive, but more accurate, ICP-OES to help determine a sculpture's artist, foundry, date of creation, date of casting, and casting method.

  11. Force Spectroscopy in Studying Infection.

    PubMed

    Zhou, Zhaokun; Leake, Mark C

    2016-01-01

    Biophysical force spectroscopy tools-for example, optical tweezers, magnetic tweezers, atomic force microscopy-have been used to study elastic, mechanical, conformational and dynamic properties of single biological specimens from single proteins to whole cells to reveal information not accessible by ensemble average methods such as X-ray crystallography, mass spectroscopy, gel electrophoresis and so on. Here, we review the application of these tools on a range of infection-related questions from antibody-inhibited protein processivity to virus-cell adhesion. In each case, we focus on how the instrumental design tailored to the biological system in question translates into the functionality suitable for that particular study. The unique insights that force spectroscopy has gained to complement knowledge learned through population averaging techniques in interrogating biomolecular details prove to be instrumental in therapeutic innovations such as those in structure-based drug design.

  12. Absorption and emission spectroscopy in natural and synthetic corundum

    NASA Astrophysics Data System (ADS)

    Spinolo, G.; Palanza, V.; Ledonne, A.; Paleari, A.

    2009-04-01

    In the frame of an extensive project on the optical characterization of the many varieties of corundum (see:www.gemdata.mater.unimib.it ) we reconsidered the current interpretation of the absorption spectra with particular attention to the bands attributed to the IVCT mechanism Fe2+→ Fe3+ and Fe2+→Ti4+. A detailed study was devoted to natural metamorphic and Verneuil synthetic pale blue sapphires . In that paper (I.Fontana et al 2008) we gave experimental evidence that the band at 17500 cm-1 often attributed to Fe2+→Ti4+ IVCT transitions is in reality due to the 4T2 crystal field transition of Cr3+ partially overlapped by the 2E of Ti3+. The results of radio and photoluminescence excitation experiments obtained there, led us to propose that the color of these sapphires is mainly due to Cr in its two valence states ; Ti 3+ and Fe3+ have a minor role. After those encouraging results, we decided to apply the same approach to the study of deep blue and yellow sapphires of magmatic origin. Evaluation of impurity ion concentration by EDXRF revealed that in all these samples the concentration of Fe is quite high (around 1%) while Cr and Ti are barely detectable. Characteristic of the absorption spectra of deep blue samples is the dominant presence of the 5E spin allowed transition of Fe2+; Fe3+ has a minor role due to the fact that all d5 transitions are spin forbidden and ,consequently, very weak. In yellow sapphires Fe is totally in its 3+ valence state. In these cases, the color from yellow to blue, sometimes even within the same sample, depends. on oxidizing or reducing growth conditions. Even if the concentrations of Cr and Ti are very low, their characteristic emissions are the only ones observable down to 10000 cm-1 in radio and photoluminescence spectra. This piece of evidence suggested us to propose for the absorption bands present in the 14000 to 21000 cm-1 range, often attributed to IVCT, the same attribution given to the analogous bands in metamorphic

  13. Absorption and emission spectroscopy of individual semiconductor nanostructures

    NASA Astrophysics Data System (ADS)

    McDonald, Matthew P.

    The advent of controllable synthetic methods for the production of semiconductor nanostructures has led to their use in a host of applications, including light-emitting diodes, field effect transistors, sensors, and even television displays. This is, in part, due to the size, shape, and morphologically dependent optical and electrical properties that make this class of materials extremely customizable; wire-, rod- and sphere-shaped nanocrystals are readily synthesized through common wet chemical methods. Most notably, confining the physical dimension of the nanostructure to a size below its Bohr radius (aB) results in quantum confinement effects that increase its optical energy gap. Not only the size, but the shape of a particle can be exploited to tailor its optical and electrical properties. For example, confined CdSe quantum dots (QDs) and nanowires (NWs) of equivalent diameter possess significantly different optical gaps. This phenomenon has been ascribed to electrostatic contributions arising from dielectric screening effects that are more pronounced in an elongated (wire-like) morphology. Semiconducting nanostructures have thus received significant attention over the past two decades. However, surprisingly little work has been done to elucidate their basic photophysics on a single particle basis. What has been done has generally been accomplished through emission-based measurements, and thus does not fully capture the full breadth of these intriguing systems. What is therefore needed then are absorption-based studies that probe the size and shape dependent evolution of nanostructure photophysics. This thesis summarizes the single particle absorption spectroscopy that we have carried out to fill this knowledge gap. Specifically, the diameter-dependent progression of one-dimensional (1D) excitonic states in CdSe NWs has been revealed. This is followed by a study that focuses on the polarization selection rules of 1D excitons within single CdSe NWs. Finally

  14. Development of the charge exchange recombination spectroscopy and the beam emission spectroscopy on the EAST tokamak

    SciTech Connect

    Li, Y. Y.; Fu, J.; Lyu, B.; Du, X. W.; Li, C. Y.; Yu, Y.; Wang, Q. P.; Zhang, Y.; Yin, X. H.; Ye, M. Y.; Wan, B. N.; Hellermann, M. von; Shi, Y. J.

    2014-11-15

    Charge eXchange Recombination Spectroscopy (CXRS) and Beam Emission Spectroscopy (BES) diagnostics based on a heating neutral beam have recently been installed on EAST to provide local measurements of ion temperature, velocity, and density. The system design features common light collection optics for CXRS and BES, background channels for the toroidal views, multi-chord viewing sightlines, and high throughput lens-based spectrometers with good signal to noise ratio for high time resolution measurements. Additionally, two spectrometers each has a tunable grating to observe any wavelength of interest are used for the CXRS and one utilizes a fixed-wavelength grating to achieve higher diffraction efficiency for the BES system. A real-time wavelength correction is implemented to achieve a high-accuracy wavelength calibration. Alignment and calibration are performed. Initial performance test results are presented.

  15. Nanoparticles and nanowires: synchrotron spectroscopy studies

    SciTech Connect

    Sham, T.K.

    2008-08-11

    This paper reviews the research in nanomaterials conducted in our laboratory in the last decade using conventional and synchrotron radiation techniques. While preparative and conventional characterisation techniques are described, emphasis is placed on the analysis of nanomaterials using synchrotron radiation. Materials of primary interests are metal nanoparticles and semiconductor nanowires and nanoribbons. Synchrotron techniques based on absorption spectroscopy such as X-ray absorption fine structures (XAFS), which includes X-ray absorption near edge structures (XANES) and extended X-ray absorption fine structures (EXFAS), and de-excitation spectroscopy, including X-ray excited optical luminescence (XEOL), time-resolved X-ray excited optical luminescence (TRXEOL) and X-ray emission spectroscopy (XES) are described. We show that the tunability, brightness, polarisation and time structure of synchrotron radiation are providing unprecedented capabilities for nanomaterials analysis. Synchrotron studies of prototype systems such as gold nanoparticles, 1-D nanowires of group IV materials, C, Si and Ge as well as nanodiamond, and compound semiconductors, ZnS, CdS, ZnO and related materials are used to illustrate the power and unique capabilities of synchrotron spectroscopy in the characterisation of local structure, electronic structure and optical properties of nanomaterials.

  16. Multiple stimulated emission fluorescence photoacoustic sensing and spectroscopy

    NASA Astrophysics Data System (ADS)

    Li, Gaoming; Gao, Fei; Qiu, Yishen; Feng, Xiaohua; Zheng, Yuanjin

    2016-07-01

    Multiple stimulated emission fluorescence photoacoustic (MSEF-PA) phenomenon is demonstrated in this letter. Under simultaneous illumination of pumping light and stimulated emission light, the fluorescence emission process is speeded up by the stimulated emission effect. This leads to nonlinear enhancement of photoacoustic signal while the quantity of absorbed photons is more than that of fluorescent molecules illuminated by pumping light. The electronic states' specificity of fluorescent molecular can also be labelled by the MSEF-PA signals, which can potentially be used to obtain fluorescence excitation spectrum in deep scattering tissue with nonlinearly enhanced photoacoustic detection. In this preliminary study, the fluorescence excitation spectrum is reconstructed by MSEF-PA signals through sweeping the wavelength of exciting light, which confirms the theoretical derivation well.

  17. Analysis of quantum semiconductor heterostructures by ballistic electron emission spectroscopy

    NASA Astrophysics Data System (ADS)

    Guthrie, Daniel K.

    1998-09-01

    The microelectronics industry is diligently working to achieve the goal of gigascale integration (GSI) by early in the 21st century. For the past twenty-five years, progress toward this goal has been made by continually scaling down device technology. Unfortunately, this trend cannot continue to the point of producing arbitrarily small device sizes. One possible solution to this problem that is currently under intensive study is the relatively new area of quantum devices. Quantum devices represent a new class of microelectronic devices that operate by utilizing the wave-like nature (reflection, refraction, and confinement) of electrons together with the laws of quantum mechanics to construct useful devices. One difficulty associated with these structures is the absence of measurement techniques that can fully characterize carrier transport in such devices. This thesis addresses this need by focusing on the study of carrier transport in quantum semiconductor heterostructures using a relatively new and versatile measurement technique known as ballistic electron emission spectroscopy (BEES). To achieve this goal, a systematic approach that encompasses a set of progressively more complex structures is utilized. First, the simplest BEES structure possible, the metal/semiconductor interface, is thoroughly investigated in order to provide a foundation for measurements on more the complex structures. By modifying the semiclassical model commonly used to describe the experimental BEES spectrum, a very complete and accurate description of the basic structure has been achieved. Next, a very simple semiconductor heterostructure, a Ga1-xAlxAs single-barrier structure, was measured and analyzed. Low-temperature measurements on this structure were used to investigate the band structure and electron-wave interference effects in the Ga1-xAlxAs single barrier structure. These measurements are extended to a simple quantum device by designing, measuring, and analyzing a set of

  18. X-ray photo-emission and energy dispersive spectroscopy of HA coated titanium

    SciTech Connect

    Drummond, J.L.; Steinberg, A.D.; Krauss, A.R.

    1997-08-01

    The purpose of this study was to determine the chemical composition changes of hydroxyapatite (HA) coated titanium using surface analysis (x-ray photo-emission) and bulk analysis (energy dispersive spectroscopy). The specimens examined were controls, 30 minutes and 3 hours aged specimens in distilled water or 0.2M sodium phosphate buffer (pH 7.2) at room temperature. Each x-ray photo-emission cycle consisted of 3 scans followed by argon sputtering for 10 minutes for a total of usually 20 cycles, corresponding to a sampling depth of {approximately} 1500 {angstrom}. The energy dispersive spectroscopy analysis was on a 110 by 90 {mu}m area for 500 sec. Scanning electron microscopy examination showed crystal formation (3P{sub 2}O{sub 5}*2CAO*?H{sub 2}O by energy dispersive spectroscopy analysis) on the HA coating for the specimens aged in sodium phosphate buffer. The x-ray photo-emission results indicated the oxidation effect of water on the titanium (as TiO{sub 2}) and the effect of the buffer to increase the surface concentration of phosphorous. No differences in the chemical composition were observed by energy dispersive spectroscopy analysis. The crystal growth was only observed for the sodium phosphate buffer specimens and only on the HA surface.

  19. Project 8: Towards cyclotron radiation emission spectroscopy on tritium

    NASA Astrophysics Data System (ADS)

    Fertl, Martin; Project 8 Collaboration

    2017-01-01

    Project 8 aims to determine the neutrino mass by making a precise measurement of the beta decay of molecular tritium (Q = 18.6 keV) using the recently demonstrated the technique of cyclotron radiation emission spectroscopy (CRES). We report on results for calibration measurements performed with Kr-83m in a gas cell that fulfills the stringent requirements for a measurement using tritium: cryogenic operation, safe tritium handling, a non-magnetic design, and a good microwave guide performance. The phased program that allows Project 8 to probe the neutrino mass range accessible using molecular tritium is described. Major financial support by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics to the University of Washington under Award Number DE-FG02-97ER41020 is acknowledged

  20. Project 8: Towards cyclotron radiation emission spectroscopy on tritium

    NASA Astrophysics Data System (ADS)

    Fertl, Martin; Project 8 Collaboration

    2016-03-01

    Project 8 aims to determine the neutrino mass by making a precise measurement of the β--decay of molecular tritium (Q = 18.6 keV) using the recently demonstrated the technique of cyclotron radiation emission spectroscopy (CRES). Here we discuss the production of a gas cell that fulfills the stringent requirements for cryogenic operation, safe tritium handling, a non-magnetic design, and a good microwave guide performance. The phased program that allows Project 8 to probe the neutrino mass range accessible using molecular tritium is described. Major financial support by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics to the University of Washington under Award Number DE-FG02-97ER41020 is acknowledged.

  1. Wide-field turbulence imaging with beam emission spectroscopy

    SciTech Connect

    McKee, G. R.; Fonck, R. J.; Uzun-Kaymak, I. U.; Yan, Z.; Shafer, M. W.

    2010-10-15

    Imaging of the size, shape, time-averaged, and time-resolved dynamics of long-wavelength density turbulence structures is accomplished with an expanded, high-sensitivity, wide-field beam emission spectroscopy (BES) diagnostic on DIII-D. A 64-channel BES system is configured with an 8x8 grid of discrete channels that image an approximately 7x9 cm region at the outboard midplane. The grid covers multiple correlation lengths and each channel shape matches the measured radial-poloidal correlation length asymmetry of turbulent eddies. The wide field 8x8 imaging capability allows for sampling of essentially the full two-dimensional spatial correlation function for typical plasma conditions. The sampled area can be radially scanned over 0.4

  2. Diglycolamide-functionalized calix[4]arenes showing unusual complexation of actinide ions in room temperature ionic liquids: role of ligand structure, radiolytic stability, emission spectroscopy, and thermodynamic studies.

    PubMed

    Mohapatra, Prasanta K; Sengupta, Arijit; Iqbal, Mudassir; Huskens, Jurriaan; Verboom, Willem

    2013-03-04

    Diglycolamide-functionalized calix[4]arenes (C4DGAs) with varying structural modifications were evaluated for actinide complexation from their extraction behavior toward actinide ions such as UO2(2+), Pu(4+), PuO2(2+), and Am(3+) in the room temperature ionic liquid (RTIL) 1-n-octyl-3-methylimidazolium bis(trifluoromethane)sulfonamide (C8mimNTf2). The formation constants were calculated for Am(3+) which showed a significant role of ligand structure, nature of substituents, and spacer length. Although the alkyl substituents on the amidic nitrogen increase the extraction efficiency of americium at lower acidity because of the inductive effect of the alkyl groups, at higher acidity the steric crowding around the ligating site determines the extraction efficiency. All C4DGAs formed 1:1 complexes with Am(3+) while for the analogous Eu(3+) complexes no inner sphere water molecules were detected and the asymmetry of the metal ligand complex differed from one another as proved by time-resolved laser induced fluorescence spectroscopy (TRLIFS). Thermodynamic studies indicated that the extraction process, predominant by the Am(3+)-C4DGA complexation reaction, is exothermic. The unique role of the medium on Am(3+) complexation with the C4DGA molecules with varying spacer length, L-IV and L-V, was noticed for the first time with a reversal in the trend observed in the RTIL compared to that seen in a nonpolar molecular diluent like n-dodecane. Various factors leading to a more preorganized structure were responsible for favorable metal ion complexation. The solvent systems show promise to be employed for nuclear waste remediation, and sustainability options were evaluated from radiolytic stability as well as stripping studies.

  3. Measurement of elemental concentration of aerosols using spark emission spectroscopy.

    PubMed

    Diwakar, Prasoon K; Kulkarni, Pramod

    A coaxial microelectrode system has been used to collect and analyse the elemental composition of aerosol particles in near real-time using spark emission spectroscopy. The technique involves focused electrostatic deposition of charged aerosol particles onto the flat tip of a microelectrode, followed by introduction of spark discharge. A pulsed spark discharge was generated across the electrodes with input energy ranging from 50 to 300 mJ per pulse, resulting in the formation of controlled pulsed plasma. The particulate matter on the cathode tip is ablated and atomized by the spark plasma, resulting in atomic emissions which are subsequently recorded using a broadband optical spectrometer for element identification and quantification. The plasma characteristics were found to be very consistent and reproducible even after several thousands of spark discharges using the same electrode system. The spark plasma was characterized by measuring the excitation temperature (~7000 to 10 000 K), electron density (~10(16) cm(-3)), and evolution of spectral responses as a function of time. The system was calibrated using particles containing Pb, Si, Na and Cr. Absolute mass detection limits in the range 11 pg to 1.75 ng were obtained. Repeatability of spectral measurements varied from 2 to 15%. The technique offers key advantages over similar microplasma-based techniques such as laser-induced breakdown spectroscopy, as: (i) it does not require any laser beam optics and eliminates any need for beam alignment, (ii) pulse energy from dc power supply in SIBS system can be much higher compared to that from laser source of the same physical size, and (iii) it is quite conducive to compact, field-portable instrumentation.

  4. Excitation emission and time-resolved fluorescence spectroscopy of selected varnishes used in historical musical instruments.

    PubMed

    Nevin, Austin; Echard, Jean-Philippe; Thoury, Mathieu; Comelli, Daniela; Valentini, Gianluca; Cubeddu, Rinaldo

    2009-11-15

    The analysis of various varnishes from different origins, which are commonly found on historical musical instruments was carried out for the first time with both fluorescence excitation emission spectroscopy and laser-induced time-resolved fluorescence spectroscopy. Samples studied include varnishes prepared using shellac, and selected diterpenoid and triterpenoid resins from plants, and mixtures of these materials. Fluorescence excitation emission spectra have been collected from films of naturally aged varnishes. In parallel, time-resolved fluorescence spectroscopy of varnishes provides means for discriminating between short- (less than 2.0 ns) and long-lived (greater than 7.5 ns) fluorescence emissions in each of these complex materials. Results suggest that complementary use of the two non destructive techniques allows a better understanding of the main fluorophores responsible for the emission in shellac, and further provides means for distinguishing the main classes of other varnishes based on differences in fluorescence lifetime behaviour. Spectrofluorimetric data and time resolved spectra presented here may form the basis for the interpretation of results from future in situ fluorescence examination and time resolved fluorescence imaging of varnished musical instruments.

  5. Effects of temporal laser profile on the emission spectra for underwater laser-induced breakdown spectroscopy: Study by short-interval double pulses with different pulse durations

    SciTech Connect

    Tamura, Ayaka Matsumoto, Ayumu; Nishi, Naoya; Sakka, Tetsuo; Nakajima, Takashi; Ogata, Yukio H.; Fukami, Kazuhiro

    2015-01-14

    We investigate the effects of temporal laser profile on the emission spectra of laser ablation plasma in water. We use short-interval (76 ns) double pulses with different pulse durations of the composing two pulses for the irradiation of underwater target. Narrow atomic spectral lines in emission spectra are obtained by the irradiation, where the two pulses are wide enough to be merged into a single-pulse-like temporal profile, while deformed spectra are obtained when the two pulses are fully separated. The behavior of the atomic spectral lines for the different pulse durations is consistent with that of the temporal profiles of the optical emission intensities of the plasma. All these results suggest that continuous excitation of the plasma during the laser irradiation for ∼100 ns is a key to obtain narrow emission spectral lines.

  6. Ballistic electron emission spectroscopy of magnetic multilayers (abstract)

    NASA Astrophysics Data System (ADS)

    First, P. N.; Bonetti, J. A.; Guthrie, D. K.; Harrell, L. E.; Parkin, S. S. P.

    1997-04-01

    The giant magnetoresistance observed in magnetic multilayers arises from spin-dependent scattering and transmission of electrons at the Fermi energy. We will describe a method for the measurement of these quantities in a "CPP" geometry at electron energies both above and below the Fermi energy. Initial results will also be presented. The measurements employ ballistic electron emission spectroscopy (BEES) to detect the ballistic electron current transmitted through a multilayer as a function of magnetic field and electron energy. The experiments are similar in concept to the "spin-valve transistor,"1 except that the injector is the tip of a scanning tunneling microscope. This allows the injection energy to be varied over a wide range, and spectra can be correlated with the local surface morphology on a nanometer scale. Spectral broadening due to sample inhomogeneities is also eliminated. We anticipate that BEES measurements and complementary scanning tunneling spectroscopy will provide information that is easily compared with calculations of the multilayer band structure and the electron transmittance versus energy.

  7. Characterization and Infrared Emission Spectroscopy of Ball Plasmoid Discharges

    NASA Astrophysics Data System (ADS)

    Dubowsky, Scott E.; McCall, Benjamin J.

    2015-06-01

    Plasmas at atmospheric pressure serve many purposes, from ionization sources for ambient mass spectrometry (AMS) to plasma-assisted wound healing. Of the many naturally occurring ambient plasmas, ball lightning is one of the least understood; there is currently no solid explanation in the literature for the formation and lifetime of natural ball lightning. With the first measurements of naturally occurring ball lightning being reported last year, we have worked to replicate the natural phenomenon in order to elucidate the physical and chemical processes by which the plasma is sustained at ambient conditions. We are able to generate ball-shaped plasmoids (self-sustaining plasmas) that are analogous to natural ball lightning using a high-voltage, high-current, pulsed DC system. Improvements to the discharge electronics used in our laboratory and characterization of the plasmoids that are generated from this system will be described. Infrared emission spectroscopy of these plasmoids reveals emission from water and hydroxyl radical -- fitting methods for these molecular species in the complex experimental spectra will be presented. Rotational temperatures for the stretching and bending modes of H2O along with that of OH will be presented, and the non-equilibrium nature of the plasmoid will be discussed in this context. Cen, J.; Yuan, P,; Xue, S. Phys. Rev. Lett. 2014, 112, 035001. Dubowsky, S.E.; Friday, D.M.; Peters, K.C.; Zhao, Z.; Perry, R.H.; McCall, B.J. Int. J. Mass Spectrom. 2015, 376, 39-45.

  8. NIR spectroscopy of Palomar emission-line galaxies

    NASA Astrophysics Data System (ADS)

    Mason, Rachel; Alonso-Herrero, Almudena; Bluck, Asa; Colina, Luis; Diaz, Ruben; Diaz-Santos, Tanio; Flohic, Helene; Gomez, Percy; Gonzalez-Martin, Omaira; Ho, Luis; Jorgensen, Inger; Lemoine-Busserolle, Marie; Levenson, Nancy; Lira, Paulina; McDermid, Richard; Perlman, Eric; Rodriguez-Ardila, Alberto; Riffel, Rogerio; Schiavon, Ricardo; Ramos Almeida, Cristina; Thanjavur, Karun; Winge, Claudia

    2012-02-01

    We propose GNIRS cross-dispersed spectroscopy of 60 Seyferts and LINERs from the Palomar galaxy sample. The spectra will advance our knowledge of AGN physics and lifecycles by demonstrating whether the accretion disk and nuclear dust properties change as a function of accretion rate, as predicted by theoretical models. They will be used to investigate the contribution of evolved stars to the line emission in LINERs, with implications for AGN demographics, and to make new stellar kinematic measurements for black hole mass estimates. The number and variety of spectral features that will appear in the data are expected to enable a wide range of science besides that highlighted in this proposal. For this reason, we plan a reduced proprietary period and to make the reduced spectra available to the community. We anticipate applying for time to observe the remaining emission-line galaxies in the (near-complete) Palomar sample over the next few semesters. The targets are distributed throughout the northern sky, making Gemini's queue mode ideal for this work. The fairly short observations are easily scheduled and can be carried out in suboptimal observing conditions.

  9. Eye-safe infrared laser-induced breakdown spectroscopy (LIBS) emissions from energetic materials

    NASA Astrophysics Data System (ADS)

    Brown, Ei E.; Hömmerich, Uwe; Yang, Clayton C.; Jin, Feng; Trivedi, Sudhir B.; Samuels, Alan C.

    2016-05-01

    Laser-induced breakdown spectroscopy is a powerful diagnostic tool for detection of trace elements by monitoring the atomic and ionic emission from laser-induced plasmas. Besides elemental emissions from conventional UV-Vis LIBS, molecular LIBS emission signatures of the target compounds were observed in the long-wave infrared (LWIR) region in recent studies. Most current LIBS studies employ the fundamental Nd:YAG laser output at 1.064 μm, which has extremely low eye-damage threshold. In this work, comparative LWIR-LIBS emissions studies using traditional 1.064 μm pumping and eye-safe laser wavelength at 1.574 μm were performed on several energetic materials for applications in chemical, biological, and explosive (CBE) sensing. A Q-switched Nd: YAG laser operating at 1.064 μm and the 1.574 μm output of a pulsed Nd:YAG pumped Optical Parametric Oscillator were employed as the excitation sources. The investigated energetic materials were studied for the appearance of LWIR-LIBS emissions (4-12 μm) that are directly indicative of oxygenated breakdown products as well as partially dissociated and recombination molecular species. The observed molecular IR LIBS emission bands showed strong correlation with FTIR absorption spectra of the studied materials for 1.064 μm and 1.574 μm pump wavelengths.

  10. Electronic emission spectroscopy of the 4-methyl-3-azabenzyl radical

    NASA Astrophysics Data System (ADS)

    Lightcap, Johnny; Butler, Joseph T.; Goebbert, Daniel J.

    2015-12-01

    The 4-methyl-3-azabenzyl radical was generated from 2,5-lutidine in a corona excited supersonic expansion, and its fluorescence emission spectrum was recorded. Two possible radical isomers could form by loss of an H atom from either methyl group in 2,5-lutidine. Theoretical studies of both isomers confirmed the only species observed was 4-methyl-3-azabenzyl. The emission spectrum corresponded to the D1 → D0 transition, with a strong origin peak and several vibronic bands. The origin transition is located at 21 401 cm-1, in good agreement with a previous assignment, and calculated vibrational energies were in good agreement experimental vibrational energies.

  11. Electrochemical flowcell for in-situ investigations by soft x-ray absorption and emission spectroscopy

    SciTech Connect

    Schwanke, C.; Lange, K. M.; Golnak, R.; Xiao, J.

    2014-10-15

    A new liquid flow-cell designed for electronic structure investigations at the liquid-solid interface by soft X-ray absorption and emission spectroscopy is presented. A thin membrane serves simultaneously as a substrate for the working electrode and solid state samples as well as for separating the liquid from the surrounding vacuum conditions. In combination with counter and reference electrodes this approach allows in-situ studies of electrochemical deposition processes and catalytic reactions at the liquid-solid interface in combination with potentiostatic measurements. As model system in-situ monitoring of the deposition process of Co metal from a 10 mM CoCl{sub 2} aqueous solution by X-ray absorption and emission spectroscopy is presented.

  12. Electrochemical flowcell for in-situ investigations by soft x-ray absorption and emission spectroscopy.

    PubMed

    Schwanke, C; Golnak, R; Xiao, J; Lange, K M

    2014-10-01

    A new liquid flow-cell designed for electronic structure investigations at the liquid-solid interface by soft X-ray absorption and emission spectroscopy is presented. A thin membrane serves simultaneously as a substrate for the working electrode and solid state samples as well as for separating the liquid from the surrounding vacuum conditions. In combination with counter and reference electrodes this approach allows in-situ studies of electrochemical deposition processes and catalytic reactions at the liquid-solid interface in combination with potentiostatic measurements. As model system in-situ monitoring of the deposition process of Co metal from a 10 mM CoCl2 aqueous solution by X-ray absorption and emission spectroscopy is presented.

  13. Bloch Surface Wave-Coupled Emission from Quantum Dots by Ensemble and Single Molecule Spectroscopy.

    PubMed

    Ray, Krishanu; Badugu, Ramachandram; Lakowicz, Joseph R

    We report the spectral properties and spatial distribution of quantum dot (QD575 ) emission on a one-dimensional photonic crystal (1DPC). Our 1DPC substrate consists of multiple layers of dielectrics with a photonic band gap (PBG) near the QD575 emission maximum. The 1DPC was designed to display a surface-trapped electromagnetic state known as a Bloch surface wave (BSW) at the 1DPC-air (sample) interface. Ensemble angle-dependent emission intensities revealed a sharp angular emission peak near 41° from the normal which is consistent with the BSW resonance at 575 nm. We further examined the emission from single QDs on the 1DPC. A notable increase in fluorescence intensity from QD575 particles was observed on BSW substrate compared to the glass substrate from the scanning confocal fluorescence images and from the intensity-time trajectories of single QD575 particles. The intensity-decays showed substantially faster decay (4-fold decrease in emission lifetime) from the single QD575 particles on 1DPC substrate (∼4.8 nsec) as compared to the glass substrate (∼18 nsec). We observed the spectral characteristics of the individual QD575 particles on 1DPC and glass substrates, by recording the single particle emission spectra through the 1DPC. The emission spectra of the single QD575 particles are similar (with emission maxima around 575 nm) on both substrates except a substantial increase in intensity (over 10-fold) on the BSW substrate. Our results demonstrate that quantum dots can interact with Bloch Surface Waves (BSW) on a 1DPC. To the best of our knowledge, this is the first report on the single particle fluorescence studies on 1DPC substrate. The 10-fold increase in intensity in combination with 4-fold reduction in emission lifetime suggest 1DPCs with BSW modes have potential use in sensing and single molecule spectroscopy.

  14. CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES: Transient surface photoconductivity of GaAs emitter studied by terahertz pump-emission spectroscopy

    NASA Astrophysics Data System (ADS)

    Shi, Yu-Lei; Zhou, Qing-Li; Zhang, Cun-Lin

    2009-10-01

    This paper investigates the ultrafast carrier dynamics and surface photoconductivity of unbiased semi-insulating GaAs in detail by using a terahertz pump-emission technique. Based on theoretical modelling, it finds that transient photoconductivity plays a very important role in the temporal waveform of terahertz radiation pulse. Anomalous enhancement in both terahertz radiation and transient photoconductivity is observed after the excitation of pump pulse and we attribute these phenomena to carrier capture in the EL2 centers. Moreover, the pump power- and temperature-dependent measurements are also performed to verify this trapping model.

  15. Optical emission spectroscopy of argon and hydrogen-containing plasmas

    NASA Astrophysics Data System (ADS)

    Siepa, Sarah; Danko, Stephan; Tsankov, Tsanko V.; Mussenbrock, Thomas; Czarnetzki, Uwe

    2015-09-01

    Optical emission spectroscopy (OES) on neutral argon is applied to investigate argon, hydrogen and hydrogen-silane plasmas. The spectra are analyzed using an extensive collisional-radiative model (CRM), from which the electron density and the electron temperature (or mean energy) can be calculated. The CRM also yields insight into the importance of different excited species and kinetic processes. The OES measurements are performed on pure argon plasmas at intermediate pressure. Besides, hydrogen and hydrogen-silane plasmas are investigated using argon as a trace gas. Especially for the gas mixture discharges, CRMs for low and high pressure differ substantially. The commonly used line-ratio technique is found to lose its sensitivity for gas mixture discharges at higher pressure. A solution using absolutely calibrated line intensities is proposed. The effect of radiation trapping and the shape of the electron energy distribution function on the results are discussed in detail, as they have been found to significantly influence the results. This work was supported by the Ruhr University Research School PLUS, funded by Germany's Excellence Initiative [DFG GSC 98/3].

  16. Thermal infrared emission spectroscopy of natural surfaces: Application to desert varnish coatings on rocks

    NASA Technical Reports Server (NTRS)

    Christensen, Philip R.; Harrison Thliveris, Stephanie

    1993-01-01

    Thermal infrared spectroscopy has become an increasingly important tool for remote compositional analysis and geologic mapping. Most published laboratory measurements have been obtained in bidirectional reflection or transmission, whereas remotely sensed thermal infrared data are obtained by measuring the emitted energy. Section 2 of this paper describes a laboratory technique for determining calibrated emissivities of natural surfaces. Equations are developed to account for the energy reflected from the environment and to determine directly the sample temperature from measurements of hot and cold blackbody targets. Two methods for determining emissivity are developed: one in which only a hot sample measurement is made and the reflected background energy is removed by modeling, and a second in which the sample is cooled and the reflected energy is measured directly. Relative emissivity can be obtained to approximately 1% and absolute emissivities can be obtained to 2-15%, depending on the validity of the assumption that the emissivity of the sample is unity at some wavelength. The emission data agree well within the hemispherically integrated reflection data but point out probelms associated with bidirectional reflectance measurements. Section 3 applies emissivity measurements to the study of layered surfaces consisting of desert varnish coatings on granite and granodiorite rock suites. Two linear models are developed: the first assumes linear mixing of independent emission from the substrate and varnish (checkerboard model); the second models tansmission through an absorbing/emitting medium. Regardless of whether the varnish is or is not relatively transparant and strongly absorptive, the spectral effect of varnish increases linearly with varnish thickness, indicating that thick patches of varnish dominate the spectral properties. As a result, medium varnish thickness can be determined from spectral measurements. In addition, the composition of a substrate can be

  17. Risk assessment of an old landfill regarding the potential of gaseous emissions--a case study based on bioindication, FT-IR spectroscopy and thermal analysis.

    PubMed

    Tintner, Johannes; Smidt, Ena; Böhm, Katharina; Matiasch, Lydia

    2012-12-01

    Risk assessment of two sections (I and II) of an old landfill (ALH) in Styria (Austria) in terms of reactivity of waste organic matter and the related potential of gaseous emissions was performed using conventional parameters and innovative tools to verify their effectiveness in practice. The ecological survey of the established vegetation at the landfill surface (plant sociological relevés) indicated no relevant emissions over a longer period of time. Statistical evaluation of conventional parameters reveals that dissolved organic carbon (DOC), respiration activity (RA(4)), loss of ignition (LOI) and total inorganic carbon (TIC) mostly influence the variability of the gas generation sum (GS(21)). According to Fourier Transform Infrared (FT-IR) spectral data and the results of the classification model the reactivity potential of the investigated sections is very low which is in accordance with the results of plant sociological relevés and biological tests. The interpretation of specific regions in the FT-IR spectra was changed and adapted to material characteristics. Contrary to mechanically-biologically treated (MBT) materials, where strong aliphatic methylene bands indicate reactivity, they are rather assigned to the C-H vibrations of plastics in old landfill materials. This assumption was confirmed by thermal analysis and the characteristic heat flow profile of plastics containing landfill samples. Therefore organic carbon contents are relatively high compared to other stable landfills as shown by a prediction model for TOC contents based on heat flow profiles and partial least squares regression (PLS-R). The stability of the landfill samples, expressed by the relation of CO(2) release and enthalpies, was compared to unreactive landfills, archeological samples, earthlike materials and hardly degradable organic matter. Due to the material composition and the aging process the landfill samples are located between hardly degradable, but easily combustible

  18. Advanced Collaborative Emissions Study (ACES)

    SciTech Connect

    Greenbaum, Daniel; Costantini, Maria; Van Erp, Annemoon; Shaikh, Rashid; Bailey, Brent; Tennant, Chris; Khalek, Imad; Mauderly, Joe; McDonald, Jacob; Zielinska, Barbara; Bemis, Jeffrey; Storey, John; Hallberg, Lance; Clark, Nigel

    2013-12-31

    The objective of the Advanced Collaborative Emissions Study (ACES) was to determine before widespread commercial deployment whether or not the new, energy-efficient, heavy duty diesel engines (2007 and 2010 EPA Emissions Standards Compliant) may generate anticipated toxic emissions that could adversely affect the environment and human health. ACES was planned to take place in three phases. In Phase 1, extensive emissions characterization of four production-intent prototype engine and control systems designed to meet 2007 standards for nitrogen oxides (NOx) and particulate matter (PM) was conducted at an existing emissions characterization facility: Southwest Research Institute (SwRI). One of the tested engines was selected (at random, after careful comparison of results) for health testing in Phase 3. In Phase 2, extensive emission characterization of three production-intent prototype engine and control systems meeting the 2010 standards (including more advanced NOx controls to meet the more stringent 2010 NOx standards) was conducted at the same test facility. In Phase 3, one engine/aftertreatment system selected from Phase 1 was further characterized during health effects studies (at an existing inhalation toxicology laboratory: Lovelace Respiratory Research Institute, [LRRI]) to form the basis of the ACES safety assessment. The Department of Energy (DOE) award provided funding for emissions characterization in Phases 1 and 2 as well as exposure characterization in Phase 3. The main health analyses in Phase 3 were funded separately and are not reported here.

  19. Workshop on Thermal Emission Spectroscopy and Analysis of Dust, Disk, and Regoliths

    NASA Technical Reports Server (NTRS)

    Sprague, Ann L. (Editor); Lynch, David K. (Editor); Sitko, Michael (Editor)

    1999-01-01

    This volume contains abstracts that have been accepted for presentation at the workshop on Thermal Emission Spectroscopy and analysis of Dust, Disks and Regoliths, held April 28-30, 1999, in Houston Texas.

  20. MEASUREMENT OF AMMONIA EMISSIONS FROM MECHANICALLY VENTILATED POULTRY HOUSES USING MULTIPATH TUNABLE DIODE LASER SPECTROSCOPY

    EPA Science Inventory

    Ammonia emissions from mechanically ventilated poultry operations are an important environmental concern. Open Path Tunable Diode Laser Absorption Spectroscopy has emerged as a robust real-time method for gas phase measurement of ammonia concentrations in agricultural settings. ...

  1. Long-wave, infrared laser-induced breakdown (LIBS) spectroscopy emissions from energetic materials.

    PubMed

    Yang, Clayton S-C; Brown, Ei E; Hommerich, Uwe; Jin, Feng; Trivedi, Sudhir B; Samuels, Alan C; Snyder, A Peter

    2012-12-01

    Laser-induced breakdown spectroscopy (LIBS) has shown great promise for applications in chemical, biological, and explosives sensing and has significant potential for real-time standoff detection and analysis. In this study, LIBS emissions were obtained in the mid-infrared (MIR) and long-wave infrared (LWIR) spectral regions for potential applications in explosive material sensing. The IR spectroscopy region revealed vibrational and rotational signatures of functional groups in molecules and fragments thereof. The silicon-based detector for conventional ultraviolet-visible LIBS operations was replaced with a mercury-cadmium-telluride detector for MIR-LWIR spectral detection. The IR spectral signature region between 4 and 12 μm was mined for the appearance of MIR and LWIR-LIBS emissions directly indicative of oxygenated breakdown products as well as dissociated, and/or recombined sample molecular fragments. Distinct LWIR-LIBS emission signatures from dissociated-recombination sample molecular fragments between 4 and 12 μm are observed for the first time.

  2. Inferring Temperature Inversions in Hot Jupiters Via Spitzer Emission Spectroscopy

    NASA Astrophysics Data System (ADS)

    Garhart, Emily; Deming, Drake; Mandell, Avi

    2016-10-01

    We present a systematic study of 35 hot Jupiter secondary eclipses, including 16 hot Jupiters never before characterized via emission, observed at the 3.6 μm and 4.5 μm bandpasses of Warm Spitzer in order to classify their atmospheric structure, namely, the existence of temperature inversions. This is a robust study in that these planets orbit stars with a wide range of compositions, temperatures, and activity levels. This diverse sample allows us to investigate the source of planetary temperature inversions, specifically, its correlation with stellar irradiance and magnetic activity. We correct for systematic and intra-pixel sensitivity effects with a pixel level decorrelation (PLD) method described in Deming et al. (2015). The relationship between eclipse depths and a best-fit blackbody function versus stellar activity, a method described in Knutson et al. (2010), will ultimately enable us to appraise the current hypotheses of temperature inversions.

  3. A Cavity Ring-Down Spectroscopy Mercury Continuous Emission Monitor

    SciTech Connect

    Christopher C. Carter

    2004-12-15

    The Sensor Research & Development Corporation (SRD) has undertaken the development of a Continuous Emissions Monitor (CEM) for mercury based on the technique of Cavity Ring-Down Spectroscopy (CRD). The project involved building an instrument for the detection of trace levels of mercury in the flue gas emissions from coal-fired power plants. The project has occurred over two phases. The first phase concentrated on the development of the ringdown cavity and the actual detection of mercury. The second phase dealt with the construction and integration of the sampling system, used to carry the sample from the flue stack to the CRD cavity, into the overall CRD instrument. The project incorporated a Pulsed Alexandrite Laser (PAL) system from Light Age Incorporated as the source to produce the desired narrow band 254 nm ultra-violet (UV) radiation. This laser system was seeded with a diode laser to bring the linewidth of the output beam from about 150 GHz to less than 60 MHz for the fundamental beam. Through a variety of non-linear optics the 761 nm fundamental beam is converted into the 254 nm beam needed for mercury detection. Detection of the mercury transition was verified by the identification of the characteristic natural isotopic structure observed at lower cavity pressures. The five characteristic peaks, due to both natural isotopic abundance and hyperfine splitting, provided a unique identifier for mercury. SRD scientists were able to detect mercury in air down below 10 parts-per-trillion by volume (pptr). This value is dependent on the pressure and temperature within the CRD cavity at the time of detection. Sulfur dioxide (SO{sub 2}) absorbs UV radiation in the same spectral region as mercury, which is a significant problem for most mercury detection equipment. However, SRD has not only been able to determine accurate mercury concentrations in the presence of SO{sub 2}, but the CRD instrument can in fact determine the SO{sub 2} concentration as well. Detection of

  4. Influences on the Emissions of Bacterial Plasmas Generated through Nanosecond Laser-Induced Breakdown Spectroscopy

    NASA Astrophysics Data System (ADS)

    Malenfant, Dylan J.

    In the past decade, laser-induced breakdown spectroscopy has been shown to provide compositional data that can be used for discrimination between bacterial specimens at the strain level. This work demonstrates the viability of this technique in a clinical setting. Studies were conducted to investigate the impact of emissions generated by a nitrocellulose filter paper background on the classification of four species: E. coli, S. epidermidis, M. smegmatis, and P. aeruginosa. Limits of detection were determined as 48+/-12 kCFU per ablation event for new mounting procedures using standard diagnostic laboratory techniques, and a device for centrifuge filtration was designed for sampling from low-titer bacterial suspensions. Plasma emissions from samples grown at biological levels of magnesium, zinc, and glucose were shown not to deviate from controls. A limit of detection for environmental zinc was found to be 11 ppm. Discrimination with heat-killed samples was demonstrated, providing a sterile diagnostic environment.

  5. Overview of the beam emission spectroscopy diagnostic system on the National Spherical Torus Experiment

    SciTech Connect

    Smith, D. R.; Fonck, R. J.; McKee, G. R.; Schoenbeck, N.; Uzun-Kaymak, I.; Winz, G.; Feder, H.; Feder, R.; Labik, G.; Stratton, B. C.

    2010-10-15

    A beam emission spectroscopy (BES) system has been installed on the National Spherical Torus Experiment (NSTX) to study ion gyroscale fluctuations. The BES system measures D{sub {alpha}} emission from a deuterium neutral heating beam. The system includes two optical views centered at r/a{approx_equal}0.45 and 0.85 and aligned to magnetic field pitch angles at the neutral beam. f/1.5 collection optics produce 2-3 cm spot sizes at the neutral beam. The initial channel layout includes radial arrays, poloidal arrays, and two-dimensional grids. Radial arrays provide coverage from r/a{approx_equal}0.1 to beyond the last-closed flux surface. Photodetectors and digital filters provide high-sensitivity, low-noise measurements at frequencies of up to 1 MHz. The BES system will be a valuable tool for investigating ion gyroscale turbulence and Alfven/energetic particle modes on NSTX.

  6. Rapid evaluation of ion thruster lifetime using optical emission spectroscopy

    NASA Technical Reports Server (NTRS)

    Rock, B. A.; Mantenieks, M. A.; Parsons, M. L.

    1985-01-01

    A major life-limiting phenomenon of electric thrusters is the sputter erosion of discharge chamber components. Thrusters for space propulsion are required to operate for extended periods of time, usually in excess of 10,000 hr. Lengthy and very costly life-tests in high-vacuum facilities have been required in the past to determine the erosion rates of thruster components. Alternative methods for determining erosion rates which can be performed in relatively short periods of time at considerably lower costs are studied. An attempt to relate optical emission intensity from an ion bombarded surface (screen grid) to the sputtering rate of that surface is made. The model used a kinetic steady-state (KSS) approach, balancing the rates of population and depopulation of ten low-lying excited states of the sputtered molybdenum atom (MoI) with those of the ground state to relate the spectral intensities of the various transitions of the MoI to the population densities. Once this is accomplished, the population density can be related to the sputtering rate of the target. Radiative and collisional modes of excitation and decay are considered. Since actual data has not been published for MoI excitation rate and decay constants, semiempirical equations are used. The calculated sputtering rate and intensity is compared to the measured intensity and sputtering rates of the 8 and 30 cm ion thrusters.

  7. Trap state spectroscopy studies and wettability modification of hydroxyapatite nanobioceramics

    NASA Astrophysics Data System (ADS)

    Aronov, Daniel; Rosenman, Gil

    2007-02-01

    Sintered hydroxyapatite coatings on titanium-based implants demonstrate beneficial biocompatibility and osteoconductivity. It has been shown that charged surface states and bulk traps located in the vicinity of the surface of the hydroxyapatite coatings strongly influence wettability properties of the hydroxyapatite and may modify biocompatibility of these nanostructured bioceramics. Combination of high-resolution electron state spectroscopy methods, thermostimulated exoelectron emission, and thermoluminescence methods, applied in this work, have allowed studying electron trap energy spectrum of the hydroxyapatite bioceramics.

  8. Unreported Emission Lines of Rb, Ce, La, Sr, Y, Zr, Pb and Se Detected Using Laser-Induced Breakdown Spectroscopy

    NASA Technical Reports Server (NTRS)

    Lepore, K. H.; Mackie, J.; Dyar, M. D.; Fassett, C. I.

    2017-01-01

    Information on emission lines for major and minor elements is readily available from the National Institute of Standards and Technology (NIST) as part of the Atomic Spectra Database. However, tabulated emission lines are scarce for some minor elements and the wavelength ranges presented on the NIST database are limited to those included in existing studies. Previous work concerning minor element calibration curves measured using laser-induced break-down spectroscopy found evidence of Zn emission lines that were not documented on the NIST database. In this study, rock powders were doped with Rb, Ce, La, Sr, Y, Zr, Pb and Se in concentrations ranging from 10 percent to 10 parts per million. The difference between normalized spectra collected on samples containing 10 percent dopant and those containing only 10 parts per million were used to identify all emission lines that can be detected using LIBS (Laser-Induced Breakdown Spectroscopy) in a ChemCam-like configuration at the Mount Holyoke College LIBS facility. These emission spectra provide evidence of many previously undocumented emission lines for the elements measured here.

  9. Optical emission spectroscopy observations of fast pulsed capillary discharge plasmas

    NASA Astrophysics Data System (ADS)

    Avaria, G.; Ruiz, M.; Guzmán, F.; Favre, M.; Wyndham, E. S.; Chuaqui, H.; Bhuyan, H.

    2014-05-01

    We present time resolved optical emission spectroscopic (OES) observations of a low energy, pulsed capillary discharage (PCD). The optical emission from the capillary plasma and plasma jets emitted from the capillary volume was recorded with with a SpectraPro 275 spectrograph, fitted with a MCP gated OMA system, with 15 ns time resolution. The discharge was operated with different gases, including argon, nitrogen, hydrogen and methane, in a repetitive pulsed discharge mode at 10-50 Hz, with, 10-12 kV pulses applied at the cathode side. The time evolution of the electron density was measured using Stark broadening of the Hβ line. Several features of the capillary plasma dynamics, such as ionization growth, wall effects and plasma jet evolution, are inferred from the time evolution of the optical emission.

  10. Xanthines Studied via Femtosecond Fluorescence Spectroscopy.

    PubMed

    Changenet-Barret, Pascale; Kovács, Lajos; Markovitsi, Dimitra; Gustavsson, Thomas

    2016-12-03

    Xanthines represent a wide class of compounds closely related to the DNA bases adenine and guanine. Ubiquitous in the human body, they are capable of replacing natural bases in double helices and give rise to four-stranded structures. Although the use of their fluorescence for analytical purposes was proposed, their fluorescence properties have not been properly characterized so far. The present paper reports the first fluorescence study of xanthine solutions relying on femtosecond spectroscopy. Initially, we focus on 3-methylxanthine, showing that this compound exhibits non-exponential fluorescence decays with no significant dependence on the emission wavelength. The fluorescence quantum yield (3 × 10(-4)) and average decay time (0.9 ps) are slightly larger than those found for the DNA bases. Subsequently, we compare the dynamical fluorescence properties of seven mono-, di- and tri-methylated derivatives. Both the fluorescence decays and fluorescence anisotropies vary only weakly with the site and the degree of methylation. These findings are in line with theoretical predictions suggesting the involvement of several conical intersections in the relaxation of the lowest singlet excited state.

  11. Non-coincident multi-wavelength emission absorption spectroscopy

    SciTech Connect

    Baumann, L.E.

    1995-02-01

    An analysis is presented of the effect of noncoincident sampling on the measurement of atomic number density and temperature by multiwavelength emission absorption. The assumption is made that the two signals, emission and transmitted lamp, are time resolved but not coincident. The analysis demonstrates the validity of averages of such measurements despite fluctuations in temperature and optical depth. At potassium-seeded MHD conditions, the fluctuations introduce additional uncertainty into measurements of potassium atom number density and temperature but do not significantly bias the average results. Experimental measurements in the CFFF aerodynamic duct with coincident and noncoincident sampling support the analysis.

  12. Photofield emission spectroscopy of the tungsten <112> band structure

    NASA Astrophysics Data System (ADS)

    Radoń, T.; Jaskółka, S.

    1991-05-01

    Optical transitions in photofield emission (PFE) characteristics from the (112) plane of tungsten have been observed at five values of photon energy in the visible range. To measure very small PFE currents modulated laser radiation and phase-sensitive detection have been used. Shoulders in the characteristics obtained with s-polarized light correspond to transitions in the bulk band structure near the Fermi level in accordance with the theoretical results of Christensen and Feuerbacher [1]. Using p-polarized light, peaks of the surface density of states, lying below the Fermi level, were observed in a good agreement with both the field and photofield emission distributions.

  13. Remote sensing of the troposphere by infrared emission spectroscopy

    NASA Technical Reports Server (NTRS)

    Beer, Reinhard; Glavich, Thomas A.

    1989-01-01

    This paper describes the concept of a cryogenic IR imaging Fourier transform spectrometer, called the Tropospheric Emission Spectrometer (TES), designed for observations of the troposphere and lower stratosphere from a near-earth orbit, using natural thermal emission and reflected sunlight. The principal molecular species to be measured by TES are O3, CO, CO2, N2O, H2O, H2O2, NO, NO2, HNO3, NH3, CH4, C2H6, C2H2, SO2, COS, CFCl3, and CF2Cl2. The TES is scheduled for a launch on the second polar platform of the Earth Observing System in 1998.

  14. A CAVITY RING-DOWN SPECTROSCOPY MERCURY CONTINUOUS EMISSION MONITOR

    SciTech Connect

    Christopher C. Carter, Ph.D.

    2003-04-01

    Accurate reporting of mercury concentration requires a detailed model that includes experimental parameters that vary, such as: pressure, temperature, concentration, absorption cross-section, and isotopic structure etc. During this quarter a theoretical model has been developed to model the 253.7 nm mercury transition. In addition, while testing the interferent species SO{sub 2}, SRD was able to determine the absorption cross-section experimentally and add this to the theoretical model. Assuming that the baseline losses are due to the mirror reflectivity and SO{sub 2}, SRD can now determine the concentrations of both mercury and SO{sub 2} from the data taken. For the CRD instrument to perform as a continuous emission monitor it will be required to monitor mercury concentrations over extended periods of time. The stability of monitoring mercury concentrations over time with the CRD apparatus was tested during the past quarter. During a test which monitored the mercury concentration every 2 seconds it was found that the standard deviation, of a signal from about 1.25 ppb Hg, was only 30 ppt. SRD continued interferent gas testing during this past quarter. This included creating a simulated flue gas composed of the gases tested individually by SRD. The detection limits for mercury, although dependent on the concentration of SO{sub 2} in the simulated gas matrix, remained well below the ppb range. It was determined that for the gases tested the only measurable changes in the baseline level occurred for SO{sub 2} and mercury. Speciation studies continued with mercury chloride (HgCl{sub 2}). This included checking for spectral speciation with both Hg and HgCl{sub 2} present in the CRD cavity. There was no observable spectral shift. Also a pyrolysis oven was incorporated into the gas delivery system both for tests with HgCl{sub 2} as well as atomization of the entire gas stream. The pyrolysis tests conducted have been inconclusive thus far.

  15. Fluorescence excitation-emission matrix spectroscopy of vitiligo skin in vivo (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Zhao, Jianhua; Richer, Vincent; Al Jasser, Mohammed; Zandi, Soodabeh; Kollias, Nikiforos; Kalia, Sunil; Zeng, Haishan; Lui, Harvey

    2016-02-01

    Fluorescence signals depend on the intensity of the exciting light, the absorption properties of the constituent molecules, and the efficiency with which the absorbed photons are converted to fluorescence emission. The optical features and appearance of vitiligo have been explained primarily on the basis of reduced epidermal pigmentation, which results in abnormal white patches on the skin. The objective of this study is to explore the fluorescence properties of vitiligo and its adjacent normal skin using fluorescence excitation-emission matrix (EEM) spectroscopy. Thirty five (35) volunteers with vitiligo were acquired using a double-grating spectrofluorometer with excitation and emission wavelengths of 260-450 nm and 300-700 nm respectively. As expected, the most pronounced difference between the spectra obtained from vitiligo lesions compared to normally pigmented skin was that the overall fluorescence was much higher in vitiligo; these differences increased at shorter wavelengths, thus matching the characteristic spectral absorption of epidermal melanin. When comparing the fluorescence spectra from vitiligo to normal skin we detected three distinct spectral bands centered at 280nm, 310nm, and 335nm. The 280nm band may possibly be related to inflammation, whereas the 335 nm band may arise from collagen or keratin cross links. The source of the 310 nm band is uncertain; it is interesting to note its proximity to the 311 nm UV lamps used for vitiligo phototherapy. These differences are accounted for not only by changes in epidermal pigment content, but also by other optically active cutaneous biomolecules.

  16. Modeling and simulation of a beam emission spectroscopy diagnostic for the ITER prototype neutral beam injector

    SciTech Connect

    Barbisan, M. Zaniol, B.; Pasqualotto, R.

    2014-11-15

    A test facility for the development of the neutral beam injection system for ITER is under construction at Consorzio RFX. It will host two experiments: SPIDER, a 100 keV H{sup −}/D{sup −} ion RF source, and MITICA, a prototype of the full performance ITER injector (1 MV, 17 MW beam). A set of diagnostics will monitor the operation and allow to optimize the performance of the two prototypes. In particular, beam emission spectroscopy will measure the uniformity and the divergence of the fast particles beam exiting the ion source and travelling through the beam line components. This type of measurement is based on the collection of the H{sub α}/D{sub α} emission resulting from the interaction of the energetic particles with the background gas. A numerical model has been developed to simulate the spectrum of the collected emissions in order to design this diagnostic and to study its performance. The paper describes the model at the base of the simulations and presents the modeled H{sub α} spectra in the case of MITICA experiment.

  17. Optical emission spectroscopy of nanosecond repetitively pulsed microplasmas generated in air at atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Orriere, Thomas; Moreau, Eric; Benard, Nicolas; Pai, David

    2015-09-01

    Nanosecond repetitively pulsed (NRP) microplasmas are generated in room temperature air at atmospheric pressure, in order to investigate the enhanced control of discharge properties via the combined effects of spatial confinement and nanosecond repetitive pulsing. Discharges were generated using high-voltage pulses of 15-ns duration applied to a tungsten pin-to-pin reactor, with inter-electrode gap distances (d) from 2 mm down to 0.2 mm. Optical emission spectroscopy and electrical characterization performed on the discharge indicate that heat transfer and plasma chemistry are influenced by the microplasma geometry. Ultrafast gas heating is observed upon deducing the rotational temperature of N2 from the measured emission spectrum of the N2 (C -->B) (0, 2) and (1, 3) transition bands, but use of the microplasma geometry (d = 0.2 mm) results in lower gas temperatures than in larger discharge gaps (d = 2 mm), including at high pulse repetition frequency (30 kHz) where substantial steady-state gas heating can occur. The measured Stark broadening of the Hα transition is significantly greater than for previously studied NRP discharges in air at atmospheric pressure, indicating that the maximum electron number density may be correspondingly much greater, up to 1018 cm-3. Furthermore, for NRP microplasmas, the intensities of emission from excited atomic ions (O+ and N+) are much higher than those of excited neutral atoms (O and N), in contrast to NRP discharges generated in larger discharge gaps.

  18. Monitoring Dielectric Thin-Film Production on Product Wafers Using Infrared Emission Spectroscopy

    SciTech Connect

    NIEMCZYK,THOMAS M.; ZHANG,SONGBIAO; HAALAND,DAVID M.

    2000-12-18

    Monitoring of dielectric thin-film production in the microelectronics industry is generally accomplished by depositing a representative film on a monitor wafer and determining the film properties off line. One of the most important dielectric thin films in the manufacture of integrated circuits is borophosphosilicate glass (BPSG). The critical properties of BPSG thin films are the boron content, phosphorus content and film thickness. We have completed an experimental study that demonstrates that infrared emission spectroscopy coupled with multivariate analysis can be used to simultaneous y determine these properties directly from the spectra of product wafers, thus eliminating the need of producing monitor wafers. In addition, infrared emission data can be used to simultaneously determine the film temperature, which is an important film production parameter. The infrared data required to make these determinations can be collected on a time scale that is much faster than the film deposition time, hence infrared emission is an ideal candidate for an in-situ process monitor for dielectric thin-film production.

  19. Undistorted X-ray Absorption Spectroscopy Using s-Core-Orbital Emissions.

    PubMed

    Golnak, Ronny; Xiao, Jie; Atak, Kaan; Unger, Isaak; Seidel, Robert; Winter, Bernd; Aziz, Emad F

    2016-05-12

    Detection of secondary emissions, fluorescence yield (FY), or electron yield (EY), originating from the relaxation processes upon X-ray resonant absorption has been widely adopted for X-ray absorption spectroscopy (XAS) measurements when the primary absorption process cannot be probed directly in transmission mode. Various spectral distortion effects inherent in the relaxation processes and in the subsequent transportation of emitted particles (electron or photon) through the sample, however, undermine the proportionality of the emission signals to the X-ray absorption coefficient. In the present study, multiple radiative (FY) and nonradiative (EY) decay channels have been experimentally investigated on a model system, FeCl3 aqueous solution, at the excitation energy of the Fe L-edge. The systematic comparisons between the experimental spectra taken from various decay channels, as well as the comparison with the theoretically simulated Fe L-edge XA spectrum that involves only the absorption process, indicate that the detection of the Fe 3s → 2p partial fluorescence yield (PFY) gives rise to the true Fe L-edge XA spectrum. The two key characteristics generalized from this particular decay channel-zero orbital angular momentum (i.e., s orbital) and core-level emission-set a guideline for obtaining undistorted X-ray absorption spectra in the future.

  20. Comprehensive Chemical Analysis of Metal Alloys by Means of Inductively Coupled Plasma Optical Emission Spectroscopy

    DTIC Science & Technology

    1985-10-01

    Multielement standard solutions were prepared from commercially available atomic absorbtion standard solutions or Spex Industries plasma-grade materials... SPECTROSCOPY W. E. Glad D"TIC LECTEfl Naval Ocean Systems Center scR. San Diego, California 92152-5000 Approved for public release; distribution unlimited 0...MEANS OF INDUCTIVELY COUPLED PLASMA OPTICAL EMISSION SPECTROSCOPY 12. PENSOIAF 111151 W.. la boron Stitaim tantlum nibim tn sten and EC zircNI in n n

  1. Continuous measurements of volcanic gases from Popocatepetl volcano by thermal emission spectroscopy

    NASA Astrophysics Data System (ADS)

    Taquet, Noemie; Stremme, Wolfgang; Meza, Israel; Grutter, Michel

    2016-04-01

    Passive volcanic gas emissions have been poorly studied despite their impact on the atmospheric chemistry with important consequences on its geochemical cycles and climate change on regional and global scale. Therefore, long-term monitoring of volcanic gas plumes and their composition are of prime importance for climatic models and the estimation of the volcanic contribution to climate change. We present a new measurement and analysis strategy based on remote thermal emission spectroscopy which can provide continuous (day and night) information of the composition of the volcanic plume. In this study we show results from the Popocatepetl volcano in Mexico with measurements performed during the year 2015 from the Altzomoni Atmospheric Observatory (19.12N, -98.65W, 3,985 masl). This site, which forms part of the RUOA (www.ruoa.unam.mx) and NDACC (https://www2.acom.ucar.edu/irwg) networks, is located north of the crater of this active volcano at 12 km distance. Emission spectra were recorded with an FTIR spectrometer (OPAG22, Bruker) at 0.5 cm-1 spectral resolution and processed using the SFIT4 radiative transfer and profile retrieval code, based on the Optimal Estimation method (Rodgers, 1976; 1990; 2000). This newly improved methodology is intercompared to a former retrieval strategy using measurements from 2008 and recent results of the variability of the SiF4/SO2 composition ratio during 2015 is presented. A discussion of how the new measurements improve the understating of the impact of volcanic gas emissions on the atmosphere on global and regional scale is included.

  2. Theoretical background of optical emission spectroscopy for analysis of atmospheric pressure plasmas

    NASA Astrophysics Data System (ADS)

    Belmonte, Thierry; Noël, Cédric; Gries, Thomas; Martin, Julien; Henrion, Gérard

    2015-12-01

    This review contains a theoretical background of optical emission spectroscopy and some selected examples of issues in the field of atmospheric plasmas. It includes elements like line broadening, emission of continua and molecules, radiation models, etc. Modernized expressions figuring the terms hidden in global constants where cgs units prevail are given together with restrictions of use. Easy-to-use formulas are provided to give access to essential plasma parameters.

  3. A von Hamos x-ray spectrometer based on a segmented-type diffraction crystal for single-shot x-ray emission spectroscopy and time-resolved resonant inelastic x-ray scattering studies.

    PubMed

    Szlachetko, J; Nachtegaal, M; de Boni, E; Willimann, M; Safonova, O; Sa, J; Smolentsev, G; Szlachetko, M; van Bokhoven, J A; Dousse, J-Cl; Hoszowska, J; Kayser, Y; Jagodzinski, P; Bergamaschi, A; Schmitt, B; David, C; Lücke, A

    2012-10-01

    We report on the design and performance of a wavelength-dispersive type spectrometer based on the von Hamos geometry. The spectrometer is equipped with a segmented-type crystal for x-ray diffraction and provides an energy resolution in the order of 0.25 eV and 1 eV over an energy range of 8000 eV-9600 eV. The use of a segmented crystal results in a simple and straightforward crystal preparation that allows to preserve the spectrometer resolution and spectrometer efficiency. Application of the spectrometer for time-resolved resonant inelastic x-ray scattering and single-shot x-ray emission spectroscopy is demonstrated.

  4. Optical emission spectroscopy of metal vapor dominated laser-arc hybrid welding plasma

    SciTech Connect

    Ribic, B.; DebRoy, T.; Burgardt, P.

    2011-04-15

    During laser-arc hybrid welding, plasma properties affect the welding process and the weld quality. However, hybrid welding plasmas have not been systematically studied. Here we examine electron temperatures, species densities, and electrical conductivity for laser, arc, and laser-arc hybrid welding using optical emission spectroscopy. The effects of arc currents and heat source separation distances were examined because these parameters significantly affect weld quality. Time-average plasma electron temperatures, electron and ion densities, electrical conductivity, and arc stability decrease with increasing heat source separation distance during hybrid welding. Heat source separation distance affects these properties more significantly than the arc current within the range of currents considered. Improved arc stability and higher electrical conductivity of the hybrid welding plasma result from increased heat flux, electron temperatures, electron density, and metal vapor concentrations relative to arc or laser welding.

  5. Imaging buried organic islands by spatially resolved ballistic electron emission spectroscopy.

    PubMed

    Goh, Kuan Eng J; Bannani, A; Troadec, C

    2008-11-05

    The well-known Au/n-Si(111) Schottky interface is modified by a discontinuous pentacene film (∼1.5 nm thick) and studied using spatially resolved ballistic electron emission spectroscopy (BEES). The pentacene film introduced subtle changes to the interface which cannot be definitively detected by current-voltage measurements or a standard BEES analysis of the barrier height. In contrast, analyzing the BEES results in a dual-parameter (transmission attenuation and barrier height) space allows the effect of the pentacene film on the Au/n-Si(111) interface to be clearly demonstrated. We found that the pentacene film behaves like a tunneling barrier and increases the distribution of local barrier heights with a tendency toward lower values. Our results highlight the potential of the dual-parameter BEES analysis for understanding local interface modification by molecules.

  6. In vivo neurochemistry with emission tomography and magnetic resonance spectroscopy: clinical applications.

    PubMed

    Del Sole, Angelo; Gambini, Anna; Falini, Andrea; Lecchi, Michela; Lucignani, Giovanni

    2002-10-01

    The assessment of neurochemical processes in vivo has received much attention in the past decade as techniques such as positron or single photon emission tomography (PET and SPET), and magnetic resonance spectroscopy (MRS) have become more available. With PET and SPET, basic processes, such as blood flow and oxygen or glucose metabolism, can be regionally assessed, along with more specific functions such as the production, release, and reuptake of neurotransmitters and their occupancy of specific receptors. At the same time, MRS can reveal changes in concentration of several hydrogenate compounds in the brain. All these methods have been extensively applied for research in neurology, and some applications have reached the clinical level, namely for the study of degenerative diseases, motor-neuron diseases, movement disorders, cerebrovascular diseases, and epilepsy. This article focuses on the most relevant information that can be obtained with these complementary techniques to help clinicians in the assessment of neurological diseases.

  7. Monitoring incinerator emissions from remote sites using Fourier transform infrared spectroscopy (FTIR)

    SciTech Connect

    Demirgian, J.C.; Spurgash, S.M.; Snyder, C.T.

    1990-01-01

    Fourier transform infrared spectroscopy (FTIR) provides the potential to monitor incinerator emissions remotely and passively from air-mounted (helicopter) or ground-mounted (car) locations. The objective of this work was to extend the application of remote FTIR as an incinerator monitor to simple mixtures released in the laboratory and in the field. Initial data were collected for two commonly used principal organic hazardous components (POHCs), chloroform and carbon tetrachloride. To simulate mixtures that are more difficult to identify and quantify, subsequent laboratory and field studies were performed with methanol and diethyl malonate mixtures. The sensitivity of the equipment is currently in the region of low parts-per-million-per meter of air measured. Remote FTIR was able to identify and quantify components with overlapping absorbances in the presence of interference from carbon dioxide. 1 ref., 5 figs., 4 tabs.

  8. Imaging buried organic islands by spatially resolved ballistic electron emission spectroscopy

    NASA Astrophysics Data System (ADS)

    Goh, Kuan Eng J.; Bannani, A.; Troadec, C.

    2008-11-01

    The well-known Au/n-Si(111) Schottky interface is modified by a discontinuous pentacene film (~1.5 nm thick) and studied using spatially resolved ballistic electron emission spectroscopy (BEES). The pentacene film introduced subtle changes to the interface which cannot be definitively detected by current-voltage measurements or a standard BEES analysis of the barrier height. In contrast, analyzing the BEES results in a dual-parameter (transmission attenuation and barrier height) space allows the effect of the pentacene film on the Au/n-Si(111) interface to be clearly demonstrated. We found that the pentacene film behaves like a tunneling barrier and increases the distribution of local barrier heights with a tendency toward lower values. Our results highlight the potential of the dual-parameter BEES analysis for understanding local interface modification by molecules.

  9. Phase-resolved emission spectroscopy of a neutraliser-free gridded ion thruster

    NASA Astrophysics Data System (ADS)

    Dedrick, James; Gibson, Andrew; Rafalskyi, Dmytro; Aanesland, Ane

    2015-09-01

    Power-efficient electric propulsion systems that operate without an external neutraliser have the potential to increase the longevity of traditional concepts. The Neptune gridded-ion thruster prototype, which uses a single radio-requency (rf) power source for plasma generation, ion acceleration and beam neutralisation, is under development. Previous research has suggested that the time-resolved electron dynamics in the plume are important for maintaining charge neutrality and overall performance. In this study, the electron dynamics in the exhaust beam are investigated within the rf cycle using phase-resolved emission spectroscopy. The results are compared with time-resolved and time-integrated electrical diagnostics to investigate the mechanisms behind beam neutralisation. This work received financial support from the York-Paris CIRC and state aid managed by the laboratory of excellence Plas@Par (ANR-11-IDEX-0004-02).

  10. Quantitative analysis of solids in motion by transient infrared emission spectroscopy using hot-gas jet excitation

    SciTech Connect

    Jones, R.W.; McClelland, J.F. )

    1990-10-01

    Quantitative compositional analysis of optically thick solids in motion is demonstrated by using transient infrared emission spectroscopy (TIRES). TIRES greatly reduces the self-absorption that normally degrades conventional emission spectra so that they closely resemble blackbody spectra. Quantitative compositional analyses of poly((methyl methacrylate)-co-(butyl methacrylate)) and poly(ethylene-co-(vinyl acetate)) with standard errors of prediction under 1% were achieved with only a few seconds of data acquisition using principal component regression. Use of a hot-gas jet in place of a laser in the TIRES technique allows study of materials that do not absorb strongly at common laser wavelengths while reducing cost and complexity.

  11. Thermal emission spectroscopy as a tool for noninvasive blood glucose measurements

    NASA Astrophysics Data System (ADS)

    Buchert, Janusz M.

    2004-08-01

    The advanced prototype presented here is based on Thermal Emission Spectroscopy (TES) and promises a new generation of non-invasive human tissue analyte instruments. The method and instrument are based on the discovery that natural mid-infrared emission from the human body, especially from the tympanic membrane, is modulated by the state of the emitting tissue. In a simple experimental arrangement, it was demonstrated that emission from glucose could be detected using room temperature detectors in a filter-based setup. Thermal infrared emission characteristics of different glucose concentrations in human plasma solutions were measured. To our knowledge, this is the first time such measurements are reported. In-vivo measurements demonstrated the reproducibility of the methodology of the non-invasive glucose monitor. The non-invasive measurement was calibrated to the serum glucose concentration using 432-paired measurements and subsequently tested (results of Power Analyses) in a blind fashion with 126-paired measurements from diabetic subjects. Non-invasive glucose results were compared with laboratory reference measurements using Error-in-Variable methods. Clark Error Grid analysis showed that 100% of the measurements fell within zones A and B (90% in zone A and 10% in zone B). The Standard Deviation for all non-invasive measured concentrations is 27 mg/dL, Mean Absolute Relative Error %MARE = 8.6, and the correlation coefficient is r = 0.94. This first independent clinical study of a non-invasive blood glucose prototype has demonstrated glucose measurements with clinically acceptable accuracy without the necessity of individual daily calibration.

  12. Imaging spectroscopy of solar microwave radiation. 1: Flaring emission

    NASA Technical Reports Server (NTRS)

    Lim, Jeremy; Gary, Dale E.; Hurford, Gordon J.; Lemen, James R.

    1994-01-01

    We present observations of an impulsive microwave burst on the Sun with both high spatial and spectral resolution, made with the Solar Array at the Owens Valley Radio Observatory (OVRO). We used the measured brightness temperature spectrum to infer the emission process responsible for each microwave source, and to derive physical conditions in the source region. We confimed our predictions using soft X-ray measurements from Geostationary Operational Environmental Satellite (GOES), soft X-ray images from Yohkoh, and H-alpha flare images together with sunspots and magnetogram images from the Big Bear Solar Observatory.

  13. A GAS TEMPERATURE PROFILE BY INFRARED EMISSION-ABSORPTION SPECTROSCOPY

    NASA Technical Reports Server (NTRS)

    Buchele, D. R.

    1994-01-01

    This computer program calculates the temperature profile of a flame or hot gas. Emphasis is on profiles found in jet engine or rocket engine exhaust streams containing water vapor or carbon dioxide as radiating gases. The temperature profile is assumed to be axisymmetric with a functional form controlled by two variable parameters. The parameters are calculated using measurements of gas radiation at two wavelengths in the infrared spectrum. Infrared emission and absorption measurements at two or more wavelengths provide a method of determining a gas temperature profile along a path through the gas by using a radiation source and receiver located outside the gas stream being measured. This permits simplified spectral scanning of a jet or rocket engine exhaust stream with the instrumentation outside the exhaust gas stream. This program provides an iterative-cyclic computation in which an initial assumed temperature profile is altered in shape until the computed emission and absorption agree, within specified limits, with the actual instrument measurements of emission and absorption. Temperature determination by experimental measurements of emission and absorption at two or more wavelengths is also provided by this program. Additionally, the program provides a technique for selecting the wavelengths to be used for determining the temperature profiles prior to the beginning of the experiment. By using this program feature, the experimenter has a higher probability of selecting wavelengths which will result in accurate temperature profile measurements. This program provides the user with a technique for determining whether this program will be sufficiently accurate for his particular application, as well as providing a means of finding the solution. The input to the program consists of four types of data: (1) computer program control constants, (2) measurements of gas radiance and transmittance at selected wavelengths, (3) tabulations from the literature of gas

  14. Updated Spitzer emission spectroscopy of bright transiting hot Jupiter HD 189733b

    SciTech Connect

    Todorov, Kamen O.; Deming, Drake; Burrows, Adam; Grillmair, Carl J.

    2014-12-01

    We analyze all existing secondary eclipse time series spectroscopy of hot Jupiter HD 189733b acquired with the now defunct Spitzer/Infrared Spectrograph (IRS) instrument. We describe the novel approaches we develop to remove the systematic effects and extract accurate secondary eclipse depths as a function of wavelength in order to construct the emission spectrum of the exoplanet. We compare our results with a previous study by Grillmair et al. that did not examine all data sets available to us. We are able to confirm the detection of a water feature near 6 μm claimed by Grillmair et al. We compare the planetary emission spectrum to three model families—based on isothermal atmosphere, gray atmosphere, and two realizations of the complex radiative transfer model by Burrows et al., adopted in Grillmair et al.'s study. While we are able to reject the simple isothermal and gray models based on the data at the 97% level just from the IRS data, these rejections hinge on eclipses measured within a relatively narrow wavelength range, between 5.5 and 7 μm. This underscores the need for observational studies with broad wavelength coverage and high spectral resolution, in order to obtain robust information on exoplanet atmospheres.

  15. HIGH-RESOLUTION SPECTROSCOPY OF [Ne II] EMISSION FROM AA Tau AND GM Aur

    SciTech Connect

    Najita, Joan R.; Doppmann, Greg W.; Bitner, Martin A.; Richter, Matthew J.; Lacy, John H.; Jaffe, Daniel T.; Carr, John S.; Meijerink, Rowin; Blake, Geoffrey A.; Herczeg, Gregory J.; Glassgold, Alfred E.

    2009-05-20

    We present high-resolution (R = 80,000) spectroscopy of [Ne II] emission from two young stars, GM Aur and AA Tau, which have moderate to high inclinations. The emission from both sources appears centered near the stellar velocity and is broader than the [Ne II] emission measured previously for the face-on disk system TW Hya. These properties are consistent with a disk origin for the [Ne II] emission we detect, with disk rotation (rather than photoevaporation or turbulence in a hot disk atmosphere) playing the dominant role in the origin of the line width. In the non-face-on systems, the [Ne II] emission is narrower than the CO fundamental emission from the same sources. If the widths of both diagnostics are dominated by Keplerian rotation, this suggests that the [Ne II] emission arises from larger disk radii on average than does the CO emission. The equivalent width of the [Ne II] emission we detect is less than that of the spectrally unresolved [Ne II] feature in the Spitzer spectra of the same sources. Variability in the [Ne II] emission or the mid-infrared continuum, a spatially extended [Ne II] component, or a very (spectrally) broad [Ne II] component might account for the difference in the equivalent widths.

  16. Emission Spectroscopy measurement of hybrid ECR-Helicon plasma source parameters

    NASA Astrophysics Data System (ADS)

    Hala, Ahmed

    2015-09-01

    Optical emission spectroscopy measurement of plasma temperature and density were conducted on KACST hybrid plasma source. The hybrid source involves ECR and helicon source operated simultanously. The results indicate that the ECR alone density is higher than the density of the combined sources while the combined temperature is lower.

  17. APPLYING OPEN-PATH OPTICAL SPECTROSCOPY TO HEAVY-DUTY DIESEL EMISSIONS

    EPA Science Inventory

    Non-dispersive infrared absorption has been used to measure gaseous emissions for both stationary and mobile sources. Fourier transform infrared spectroscopy has been used for stationary sources as both extractive and open-path methods. We have applied the open-path method for bo...

  18. Thermal infrared reflectance and emission spectroscopy of quartzofeldspathic glasses

    USGS Publications Warehouse

    Byrnes, J.M.; Ramsey, M.S.; King, P.L.; Lee, R.J.

    2007-01-01

    This investigation seeks to better understand the thermal infrared (TIR) spectral characteristics of naturally-occurring amorphous materials through laboratory synthesis and analysis of glasses. Because spectra of glass phases differ markedly from their mineral counterparts, examination of glasses is important to accurately determine the composition of amorphous surface materials using remote sensing datasets. Quantitatively characterizing TIR (5-25 ??m) spectral changes that accompany structural changes between glasses and mineral crystals provides the means to understand natural glasses on Earth and Mars. A suite of glasses with compositions analogous to common terrestrial volcanic glasses was created and analyzed using TIR reflectance and emission techniques. Documented spectral characteristics provide a basis for comparison with TIR spectra of other amorphous materials (glasses, clays, etc.). Our results provide the means to better detect and characterize glasses associated with terrestrial volcanoes, as well as contribute toward understanding the nature of amorphous silicates detected on Mars. Copyright 2007 by the American Geophysical Union.

  19. Thermal Infrared Emission Spectroscopy of Synthetic Allophane and its Potential Formation on Mars

    NASA Technical Reports Server (NTRS)

    Rampe, E. B.; Kraft, M. D.; Sharp, T. G.; Golden, D. C.; Ming, Douglas W.

    2010-01-01

    Allophane is a poorly-crystalline, hydrous aluminosilicate with variable Si/Al ratios approx.0.5-1 and a metastable precursor of clay minerals. On Earth, it forms rapidly by aqueous alteration of volcanic glass under neutral to slightly acidic conditions [1]. Based on in situ chemical measurements and the identification of alteration phases [2-4], the Martian surface is interpreted to have been chemically weathered on local to regional scales. Chemical models of altered surfaces detected by the Mars Exploration Rover Spirit in Gusev crater suggest the presence of an allophane-like alteration product [3]. Thermal infrared (TIR) spectroscopy and spectral deconvolution models are primary tools for determining the mineralogy of the Martian surface [5]. Spectral models of data from the Thermal Emission Spectrometer (TES) indicate a global compositional dichotomy, where high latitudes tend to be enriched in a high-silica material [6,7], interpreted as high-silica, K-rich volcanic glass [6,8]. However, later interpretations proposed that the high-silica material may be an alteration product (such as amorphous silica, clay minerals, or allophane) and that high latitude surfaces are chemically weathered [9-11]. A TIR spectral library of pure minerals is available for the public [12], but it does not contain allophane spectra. The identification of allophane on the Martian surface would indicate high water activity at the time of its formation and would help constrain the aqueous alteration environment [13,14]. The addition of allophane to the spectral library is necessary to address the global compositional dichotomy. In this study, we characterize a synthetic allophane by IR spectroscopy, X-ray diffraction (XRD), and transmission electron microscopy (TEM) to create an IR emission spectrum of pure allophane for the Mars science community to use in Martian spectral models.

  20. Feasibility of Valence-to-Core X-ray Emission Spectroscopy for Tracking Transient Species

    PubMed Central

    2015-01-01

    X-ray spectroscopies, when combined in laser-pump, X-ray-probe measurement schemes, can be powerful tools for tracking the electronic and geometric structural changes that occur during the course of a photoinitiated chemical reaction. X-ray absorption spectroscopy (XAS) is considered an established technique for such measurements, and X-ray emission spectroscopy (XES) of the strongest core-to-core emission lines (Kα and Kβ) is now being utilized. Flux demanding valence-to-core XES promises to be an important addition to the time-resolved spectroscopic toolkit. In this paper we present measurements and density functional theory calculations on laser-excited, solution-phase ferrocyanide that demonstrate the feasibility of valence-to-core XES for time-resolved experiments. We discuss technical improvements that will make valence-to-core XES a practical pump–probe technique. PMID:26568779

  1. Analysis of fertilizers for major, micro, and trace elements by inductively coupled plasma emission spectroscopy

    NASA Astrophysics Data System (ADS)

    Jones, J. B., Jr.

    The concentrations of nine elements (B, Ca, Cu, Fe, K, Mg, Mn, P, and Zn) in 34 Magruder Fertilizer Standards were determined by inductively coupled plasma (ICP) emission spectroscopy, and the results compared favorably with the known concentrations for all the elements. In addition to these nine fertilizer elements, six others (AI, Cd, Cr, Na, Ni, and Pb) were determined in the same analysis, although results could only be compared to similar analyses made by two other laboratories employing ICP. All 15 elements were also determined in 12 spent acids used to manufacture liquid fertilizer and analysis results compared among the three laboratories. Analysis by ICP spectroscopy of fertilizer materials with wide ranges of elemental contents was found to be a rapid analysis technique which can give comparable results with those obtained by the more laborious AOAC procedures as well as the opportunity to determine other than only the important fertilizer elements. Collaborative study is recommended for ICP determination of the elements of importance in fertilizers for adaptation of the ICP technique by the Association of Official Analytical Chemists.

  2. New method for estimating greenhouse gas emissions from livestock buildings using open-path FTIR spectroscopy

    NASA Astrophysics Data System (ADS)

    Briz, Susana; Barrancos, José; Nolasco, Dácil; Melián, Gladys; Padrón, Eleazar; Pérez, Nemesio

    2009-09-01

    It is widely known that methane, together with carbon dioxide, is one of the most effective greenhouse gases contributing to climate global change. According to EMEP/CORINAIR Emission Inventory Guidebook1, around 25% of global CH4 emissions originate from animal husbandry, especially from enteric fermentation. However, uncertainties in the CH4 emission factors provided by EMEP/CORINAIR are around 30%. For this reason, works addressed to calculate emissions experimentally are so important to improve the estimations of emissions due to livestock and to calculate emission factors not included in this inventory. FTIR spectroscopy has been frequently used in different methodologies to measure emission rates in many environmental problems. Some of these methods are based on dispersion modelling techniques, wind data, micrometeorological measurements or the release of a tracer gas. In this work, a new method for calculating emission rates from livestock buildings applying Open-Path FTIR spectroscopy is proposed. This method is inspired by the accumulation chamber method used for CO2 flux measurements in volcanic areas or CH4 flux in wetlands and aquatic ecosystems. The process is the following: livestock is outside the building, which is ventilated in order to reduce concentrations to ambient level. Once the livestock has been put inside, the building is completely closed and the concentrations of gases emitted by livestock begin to increase. The Open-Path system measures the concentration evolution of gases such as CO2, CH4, NH3 and H2O. The slope of the concentration evolution function, dC/dt, at initial time is directly proportional to the flux of the corresponding gas. This method has been applied in a cow shed in the surroundings of La Laguna, Tenerife Island, Spain). As expected, evolutions of gas concentrations reveal that the livestock building behaves like an accumulation chamber. Preliminary results show that the CH4 emission factor is lower than the proposed by

  3. Infrared and infrared emission spectroscopy of the zinc carbonate mineral smithsonite

    NASA Astrophysics Data System (ADS)

    Frost, Ray L.; Martens, Wayde N.; Wain, Daria L.; Hales, Matt C.

    2008-10-01

    Infrared emission and infrared spectroscopy has been used to study a series of selected natural smithsonites from different origins. An intense broad infrared band at 1440 cm -1 is assigned to the ν CO 32- antisymmetric stretching vibration. An additional band is resolved at 1335 cm -1. An intense sharp Raman band at 1092 cm -1 is assigned to the CO 32- symmetric stretching vibration. Infrared emission spectra show a broad antisymmetric band at 1442 cm -1 shifting to lower wavenumbers with thermal treatment. A band observed at 870 cm -1 with a band of lesser intensity at 842 cm -1 shifts to higher wavenumbers upon thermal treatment and is observed at 865 cm -1 at 400 °C and is assigned to the CO 32-ν mode. No ν bending modes are observed in the Raman spectra for smithsonite. The band at 746 cm -1 shifts to 743 cm -1 at 400 °C and is attributed to the CO 32-ν in phase bending modes. Two infrared bands at 744 and around 729 cm -1 are assigned to the ν in phase bending mode. Multiple bands may be attributed to the structural distortion ZnO 6 octahedron. This structural distortion is brought about by the substitution of Zn by some other cation. A number of bands at 2499, 2597, 2858, 2954 and 2991 cm -1 in both the IE and infrared spectra are attributed to combination bands.

  4. Determination of minor elements in water by emission spectroscopy

    USGS Publications Warehouse

    Barnett, Paul R.; Mallory, E.C.

    1971-01-01

    With the emission spectrograph, the analyst is able to determine many minor elements simultaneously in water samples. Spectrographic methods differ chiefly in techniques of preconcentrating the elements. For waters with dissolved solids of less than 1,000 milligrams per liter, the method of evaporating to dryness and determining the elements in the dried residue is sensitive, precise, and reasonably accurate. The lower limits of detection vary with the quantity of dissolved solids. Twenty-four elements are determined by this method. For waters with more than 1,000 milligrams per liter of dissolved solids, it is necessary to separate the minor elements from the major constituents before spectrographically determining the former, in order to achieve adequate lower limits of detection. Such procedures generally require more time than the residue method. In the first of two such procedures given, 21 of the metallic elements are precipitated with thioacetamide prior to spectrographic determination. In an alternate procedure, 18 elements are precipitated quantitatively with complexing reagents 8-hydroxyquinoline, tannic acid, and thioanlide. This method is faster than the thioacetamide method, but at the sacrifice of some elements. A Fortran IV computer program for processing densitometric data is given in the section 'Computer Program.'

  5. Emission Spectroscopy and Ab Initio Calculations for TaN

    NASA Astrophysics Data System (ADS)

    Ram, R. S.; Liévin, J.; Bernath, P. F.

    2002-10-01

    The emission spectra of TaN have been investigated in the region 3000-35 000 cm -1 using a Fourier transform spectrometer. The spectra were observed in a tantalum hollow-cathode lamp by discharging a mixture of 1.5 Torr of Ne and about 6 mTorr of N 2. In addition to previously known bands, numerous additional bands were observed and assigned to a number of new transitions. The spectroscopic properties of the low-lying electronic states of TaN were also predicted by ab initio calculations. A 1Σ + state, with equilibrium constants of Be=0.457 852 1(48) cm -1, α e=0.002 235 9(67) cm -1, and Re=1.683 099 9(88) Å, has been identified as the ground state of TaN based on our experimental observations supported by the ab initio results. The first excited state has been identified as the a3Δ 1 spin component at 2827 cm -1 above the ground state. To higher energies, the states become difficult to assign because of their Hund's case (c) behavior and extensive interactions between the spin components of the electronic terms.

  6. Measurements of methane emissions from landfills using mobile plume method with trace gas and cavity ring-down spectroscopy

    NASA Astrophysics Data System (ADS)

    Mønster, J.; Kjeldsen, P.; Scheutz, C.

    2012-04-01

    Methane is emitted to the atmosphere from both anthropogenic and natural sources. One of the major anthropogenic sources is methane produced by bacteria in anaerobic environments such as rice pads and landfills. Land filling has for many years been the preferred waste disposal method, resulting in a large methane production with a large contribution to the global increase in atmospheric green house gas concentration. Several steps have been taken to reduce the emission of methane from landfills. In order to validate the effect of these steps, a measurement method is needed to quantify methane emissions with a large spatial variation. One method is to use a highly sensitive and fast analytical method, capable of measuring the atmospheric concentration methane downwind from emission areas. Combined with down-wind measurements of a trace gas, emitted at a controlled mass flow rate, the methane emission can be calculated. This method is called the mobile plume method, as the whole plume is measured by doing several transects. In the current study a methane/acetylene analyzer with cavity ring-down spectroscopy detection (Picarro, G2203) was used to estimate methane from a number of Danish landfills. We measured at both active and closed landfills and investigated the difference in methane emission. At landfills where the emissions could have more than one origin, the source strength of the different emission areas was determined by accurate trace gas positioning and choosing appropriate wind speed and measurement distance. To choose these factors, we addressed the uncertainties and limitations of the method with respect to the configuration of the trace gas bottles and the distance between the emission area and the measurement points. Composting of organic material in large piles was done at several of the investigated landfills and where possible, the methane emission from this partly anaerobic digestion was measured as a separate emission.

  7. Study Acoustic Emissions from Composites

    NASA Technical Reports Server (NTRS)

    Walker, James L.; Workman, Gary L.

    1997-01-01

    The nondestructive evaluation (NDE) of future propulsion systems utilizing advanced composite structures for the storage of cryogenic fuels, such as liquid hydrogen or oxygen, presents many challenges. Economic justification for these structures requires, light weight, reusable components with an infrastructure allowing periodic evaluation of structural integrity after enduring demanding stresses during operation. A major focus has been placed on the use of acoustic emission NDE to detect propagating defects, in service, necessitating an extensive study into characterizing the nature of acoustic signal propagation at very low temperatures and developing the methodology of applying AE sensors to monitor cryogenic components. This work addresses the question of sensor performance in the cryogenic environment. Problems involving sensor mounting, spectral response and durability are addressed. The results of this work provides a common point of measure from which sensor selection can be made when testing composite components at cryogenic temperatures.

  8. Lattice Studies of Hyperon Spectroscopy

    SciTech Connect

    Richards, David G.

    2016-04-01

    I describe recent progress at studying the spectrum of hadrons containing the strange quark through lattice QCD calculations. I emphasise in particular the richness of the spectrum revealed by lattice studies, with a spectrum of states at least as rich as that of the quark model. I conclude by prospects for future calculations, including in particular the determination of the decay amplitudes for the excited states.

  9. X-ray absorption and emission spectroscopy study of Mn and Co valence and spin states in TbM n1 -xC oxO3

    NASA Astrophysics Data System (ADS)

    Cuartero, V.; Lafuerza, S.; Rovezzi, M.; García, J.; Blasco, J.; Subías, G.; Jiménez, E.

    2016-10-01

    The valence and spin state evolution of Mn and Co on TbM n1 -xC oxO3 series is precisely determined by means of soft and hard x-ray absorption spectroscopy (XAS) and K β x-ray emission spectroscopy (XES). Our results show the change from M n3 + to M n4 + both high-spin (HS) together with the evolution from C o2 + HS to C o3 + low-spin (LS) with increasing x . In addition, high energy resolution XAS spectra on the K pre-edge region are interpreted in terms of the strong charge transfer and hybridization effects along the series. These results correlate well with the spin values of Mn and Co atoms obtained from the K β XES data. In this paper, we determine that Co enters into the transition metal sublattice of TbMn O3 as a divalent ion in HS state, destabilizing the Mn long-range magnetic order since very low doping compositions (x ≤0.1 ). Samples in the intermediate composition range (0.4 ≤x ≤0.6 ) adopt the crystal structure of a double perovskite with long-range ferromagnetic ordering which is due to M n4 + -O-C o2 + superexchange interactions with both cations in HS configuration. Ferromagnetism vanishes for x ≥0.7 due to the structural disorder that collapses the double perovskite structure. The spectroscopic techniques reveal the occurrence of M n4 + HS and a fluctuating valence state C o2 + HS/C o3 + LS in this composition range. Disorder and competitive interactions lead to a magnetic glassy behavior in these samples.

  10. Nuclear-spectroscopy problems studied with neutrons

    SciTech Connect

    Raman, S.

    1982-01-01

    Nuclear spectroscopy with neutrons continues to have a major impact on the progress of nuclear science. Neutrons, being uncharged, are particularly useful for the study of low energy reactions. Recent advances in time-of-flight spectroscopy, as well as in the gamma ray spectroscopy following neutron capture, have permitted precision studies of unbound and bound nuclear levels and related phenomena. By going to new energy domains, by using polarized beams and targets, through the invention of new kinds of detectors, and through the general improvement in beam quantity and quality, new features of nuclear structure and reactions have been obtained that are not ony interesting per se but are also grist for old and new theory mills. The above technical advances have opened up new opportunities for further discoveries.

  11. Nuclear-spectroscopy problems studied with neutrons

    NASA Astrophysics Data System (ADS)

    Raman, S.

    Nuclear spectroscopy with neutrons continues to have a major impact on the progress of nuclear science. Neutrons, being uncharged, are particularly useful for the study of low energy reactions. Recent advances in time-of-flight spectroscopy, as well as in the gamma ray spectroscopy following neutron capture, have permitted precision studies of unbound and bound nuclear levels and related phenomena. By going to new energy domains, by using polarized beams and targets, through the invention of new kinds of detectors, and through the general improvement in beam quantity and quality, new features of nuclear structure and reactions were obtained that are not only interesting per se but are also grist for old and new theory mills. The above technical advances have opened up opportunities for further discoveries.

  12. Study of virus by Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Moor, K.; Kitamura, H.; Hashimoto, K.; Sawa, M.; Andriana, B. B.; Ohtani, K.; Yagura, T.; Sato, H.

    2013-02-01

    Problem of viruses is very actual for nowadays. Some viruses, which are responsible for human of all tumors, are about 15 %. Main purposes this study, early detection virus in live cell without labeling and in the real time by Raman spectroscopy. Micro Raman spectroscopy (mRs) is a technique that uses a Raman spectrometer to measure the spectra of microscopic samples. According to the Raman spectroscopy, it becomes possible to study the metabolites of a live cultured cell without labeling. We used mRs to detect the virus via HEK 293 cell line-infected adenovirus. We obtained raman specters of lives cells with viruses in 24 hours and 7 days after the infection. As the result, there is some biochemical changing after the treatment of cell with virus. One of biochemical alteration is at 1081 cm-1. For the clarification result, we use confocal fluorescent microscopy and transmission electron microscopy (TEM).

  13. A CAVITY RING-DOWN SPECTROSCOPY MERCURY CONTINUOUS EMISSION MONITOR

    SciTech Connect

    Christopher C. Carter, Ph.D.

    2003-06-30

    Previous work on the detection of mercury using the cavity ring-down (CRD) technique has concentrated on the detection and characterization of the desired mercury transition. Interferent species present in flue gas emissions have been tested as well as a simulated flue gas stream. Additionally, work has been done on different mercury species such as the elemental and oxidized forms. The next phase of the effort deals with the actual sampling system. This sampling system will be responsible for acquiring a sample stream from the flue gas stack, taking it to the CRD cavity where it will be analyzed and returning the gas stream to the stack. In the process of transporting the sample gas stream every effort must be taken to minimize any losses of mercury to the walls of the sampling system as well as maintaining the mercury in its specific state (i.e. elemental, oxidized, or other mercury compounds). SRD first evaluated a number of commercially available sampling systems. These systems ranged from a complete sampling system to a number of individual components for specific tasks. SRD engineers used some commercially available components and designed a sampling system suited to the needs of the CRD instrument. This included components such as a pyrolysis oven to convert all forms of mercury to elemental mercury, a calibration air source to ensure mirror alignment and quality of the mirror surfaces, and a pumping system to maintain the CRD cavity pressure from atmospheric pressure (760 torr) down to about 50 torr. SRD also began evaluating methods for the CRD instrument to automatically find the center of a mercury transition. This procedure is necessary as the instrument must periodically measure the baseline losses of the cavity off of the mercury resonance and then return to the center of the transition to accurately measure the mercury concentration. This procedure is somewhat complicated due to the isotopic structure of the 254 nm mercury transition. As a result of

  14. A CAVITY RING-DOWN SPECTROSCOPY MERCURY CONTINUOUS EMISSION MONITOR

    SciTech Connect

    Christopher C. Carter

    2004-03-31

    The construction of the sampling system was completed during the past quarter. The sampling system has been built on a 3 feet x 4 feet x 2 inch breadboard table. The laser system, all the associated optics, and the mounts and hardware needed to couple the UV light into the fiber optic have also been condensed and placed on an identical 3 feet x 4 feet x 2 inch breadboard table. This reduces the footprint of each system for ease of operation at a field test facility. The two systems are only connected with a fiber optic, to bring the UV light to the CRD cavity, and a single coaxial cable used to apply a voltage to the diode seed laser to scan the frequency over the desired mercury transition. SRD software engineers applied a couple of software fixes to correct the problems of the diode seed laser drifting or mode hopping. Upon successful completion of the software fixes another long-term test was conducted. A nearly 3 day long, 24 hours/day, test was run to test out the new subroutines. Everything appeared to work as it should and the mercury concentrations were accurately reported for the entire test, with the exception of a small interval of time when the intensity of the UV light dropped low enough that the program was no longer triggering properly. After adjusting the power of the laser the program returned to proper operation. With the successful completion of a relatively long test SRD software engineer incorporated the new subroutine into an entirely new program. This program operates the CRD instrument automatically as a continuous emissions monitor for mercury. In addition the program also reports the concentration of SO{sub 2} determined in the sample flue gas stream. Various functions, operation of, and a description of the new program have been included with this report. This report concludes the technical work associated with Phase II of the Cavity Ring-Down project for the continuous detection of trace levels of mercury. The project is presently

  15. Visible emission spectroscopy of highly charged tungsten ions in LHD: II. Evaluation of tungsten ion temperature

    NASA Astrophysics Data System (ADS)

    Fujii, K.; Takahashi, Y.; Nakai, Y.; Kato, D.; Goto, M.; Morita, S.; Hasuo, M.; Experiment Group2, LHD

    2015-12-01

    We demonstrated a polarization-resolved high resolution spectroscopy of a visible emission line of highly charged tungsten ions (λ0 = 668.899 nm, Shinohara et al Phys. Scr. 90 125402) for the large helical device (LHD) plasma, where the tungsten ions were introduced by a pellet injection. Its spectral profile shows broadening and polarization dependence, which are attributed to the Doppler and Zeeman effects, respectively. The tungsten ion temperature was evaluated for the first time from the broadening of visible the emission line, with its emission location determined by the Abel inversion of the chord-integrated emission intensities observed with multiple chords. The tungsten ion temperature was found to be close to the helium-like argon ion temperature, which is used as an ion temperature monitor in LHD.

  16. Minority-carrier emission effect in deep level transient spectroscopy measurements on Schottky diodes

    SciTech Connect

    Lee, W.I.; Borrego, J.M.

    1988-06-01

    One basic assumption underlying all the deep level transient spectroscopy derivations is the existence of a single dominant emission process during the transient. It is demonstrated in this paper that the use of conventional procedure could result in significant errors in all the calculated defect parameters when the concerned level has comparable emission rates for both carriers in the detected range. A simple verification method and an improved scheme are proposed to determine the accurate defect parameters. By using this scheme, it is confirmed that EL2 in GaAs is an electron trap with a dominant electron emission rate. A level, designated as E3, in Si shows similar electron and hole emission rates in detected range. It is proven for this level that the conventional Arrhenius plot will lead to large errors in all the calculated defect properties, while the improved scheme provides the accurate information.

  17. Kinetic model of atomic and molecular emissions in laser-induced breakdown spectroscopy of organic compounds.

    PubMed

    Ma, Qianli; Dagdigian, Paul J

    2011-07-01

    A kinetic model previously developed to predict the relative intensities of atomic emission lines in laser-induced breakdown spectroscopy has been extended to include processes related to CN and C(2) molecular emissions. Simulations with this model were performed to predict the relative excited-state populations. The results from the simulations are compared with experimentally determined excited-state populations from 1,064 nm laser irradiation of organic residues on aluminum foil. The model reasonably predicts the relative intensity of the molecular emissions. Significantly, the model reproduces the vastly different temporal profiles of the atomic and molecular emissions. The latter are found to extend to much longer times after the laser pulse, and this appears to be due to the increasing concentration of the molecules versus time. From the simulations, the important processes affecting the CN and C(2) concentrations are identified.

  18. Nitrogen termination of single crystal (100) diamond surface by radio frequency N{sub 2} plasma process: An in-situ x-ray photoemission spectroscopy and secondary electron emission studies

    SciTech Connect

    Chandran, Maneesh E-mail: choffman@tx.technion.ac.il; Shasha, Michal; Michaelson, Shaul; Hoffman, Alon E-mail: choffman@tx.technion.ac.il

    2015-09-14

    In this letter, we report the electronic and chemical properties of nitrogen terminated (N-terminated) single crystal (100) diamond surface, which is a promising candidate for shallow NV{sup −} centers. N-termination is realized by an indirect RF nitrogen plasma process without inducing a large density of surface defects. Thermal stability and electronic property of N-terminated diamond surface are systematically investigated under well-controlled conditions by in-situ x-ray photoelectron spectroscopy and secondary electron emission. An increase in the low energy cut-off of the secondary electron energy distribution curve (EDC), with respect to a bare diamond surface, indicates a positive electron affinity of the N-terminated diamond. Exposure to atomic hydrogen results in reorganization of N-terminated diamond to H-terminated diamond, which exhibited a negative electron affinity surface. The change in intensity and spectral features of the secondary electron EDC of the N-terminated diamond is discussed.

  19. Broadband UV spectroscopy system used for monitoring of SO 2 and NO emissions from thermal power plants

    NASA Astrophysics Data System (ADS)

    Zhang, Y. G.; Wang, H. S.; Somesfalean, G.; Wang, Z. Y.; Lou, X. T.; Wu, S. H.; Zhang, Z. G.; Qin, Y. K.

    2010-11-01

    A gas monitoring system based on broadband absorption spectroscopic techniques in the ultraviolet region is described and tested. The system was employed in real-time continuous concentration measurements of sulfur dioxide (SO 2) and nitric oxide (NO) from a 220-ton h -1 circulating fluidized bed (CFB) boiler in Shandong province, China. The emission coefficients (per kg of coal and per kWh of electricity) and the total emission of the two pollutant gases were evaluated. The measurement results showed that the emission concentrations of SO 2 and NO from the CFB boiler fluctuated in the range of 750-1300 mg m -3 and 100-220 mg m -3, respectively. Compared with the specified emission standards of air pollutants from thermal power plants in China, the values were generally higher for SO 2 and lower for NO. The relatively high emission concentrations of SO 2 were found to mainly depend on the sulfur content of the fuel and the poor desulfurization efficiency. This study indicates that the broadband UV spectroscopy system is suitable for industrial emission monitoring and pollution control.

  20. Investigation of surface structure with X-ray absorption and electron emission spectroscopies

    NASA Astrophysics Data System (ADS)

    Pauli, Mark Daniel

    The use of electron spectromicroscopy for the study of the chemical composition and electronic properties of surfaces, overlayers, and interfaces has become widely accepted. Improvements to the optics of instruments such as the X-ray photo electron emission microscope have pushed spectroscopic microscopies into the realm of very high spatial resolution, at and below 1 micrometer [1]. Coupled with the high spectral resolution available from third generation synchrotron sources, this spatial resolution allows the measurement of micro-X-ray absorption near-edge spectra in addition to the more typical electron emission spectra and diffraction patterns. Complementary to the experimental developments is the development of improved theoretical methods for computational modeling of X-ray absorption and emission spectroscopies. In the field of tribochemistry, zinc dialkyl dithiophosphate (ZDDP) has long been a topic of much study. ZDDP is widely used as an anti-wear additive in engine oils and there is interest in determining the decomposition products of ZDDP that provide this protection against friction. An analysis of X-ray absorption near-edge spectra of thermal films from ZDDP samples is presented, including a comparison of the Zinc L-edge spectra with model calculations [2]. It was found essential to carry out self-consistent calculations of the electronic structure for the modeling. For the techniques of electron diffraction, a new method for a full multiple-scattering calculation of diffraction patterns from crystals with two-dimensional periodicity parallel to the surface is presented [3]. The calculation makes use of Helmholtz's reciprocity principle to compute the path-reversed process of the back propagation of a photoelectron from the position of a distant detector to that of the emitting atom. Early application is demonstrated with simulations of 64 eV M2,3VV and 914 eV L 2,3VV Auger electron diffraction from a Cu(001) surface. The functionality of the path

  1. Note: Liquid chemical sensing by emission spectroscopy with a nanosecond pin-hole discharge in water.

    PubMed

    Xia, H; Yang, Y

    2015-01-01

    This paper presents a simple yet effective method for chemical detection by emission spectroscopy using a nanosecond pin-hole discharge in water. The discharge was produced in a 200-μm-diameter microchannel in water without electrode contact. The simultaneous detection of multiple mineral ions was demonstrated by measuring the intensity of Na and Ca emission lines at different concentrations. The device can be further scaled down to be integrated with microfluidic systems for monitoring water contamination or hazardous materials in other aqueous solutions.

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

    SciTech Connect

    Fara, M.; Novak, F.

    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).

  3. Statistical analysis of excitation-emission matrices for laser-induced fluorescence spectroscopy

    NASA Astrophysics Data System (ADS)

    Maslov, N. A.; Papaeva, E. O.

    2016-07-01

    An algorithm for statistical processing of the set of multicomponent excitation-emission matrices for laser-induced fluorescence spectroscopy is proposed that is based on principal component analysis. It is shown for the first time that the fluorescence emission and excitation spectra of unknown fluorophores in optically thin samples can be calculated. Using the proposed algorithm, it is possible to pass from principal components with alternating signs to positive quantities corresponding to the spectra of real substances. The method is applied to a mixture of three fluorescent dyes, and it is demonstrated that the obtained spectra of principal components well reproduce the spectra of initial dyes.

  4. Detection of Bioaerosols using Single Particle Thermal Emission Spectroscopy

    DTIC Science & Technology

    2013-03-01

    the optical void(s) created by the aberration. Particle materials successfully trapped include carbon, silica, ragweed pollen , albumin, and...of-concept study will yield similar results when applied to a larger set of biologically derived materials, e.g., pollen , amino acids, proteins...Chang, R. Dual-excitation- wavelength Fluorescence and Elastic Scattering for Differentiation of Single Airborne Pollen and Fungal Particles

  5. Enhanced 1G 4 emission in NaLaF 4: Pr 3+, Yb 3+ and charge transfer in NaLaF 4: Ce 3+, Yb 3+ studied by fourier transform luminescence spectroscopy

    NASA Astrophysics Data System (ADS)

    van der Kolk, E.; Ten Kate, O. M.; Wiegman, J. W.; Biner, D.; Krämer, K. W.

    2011-05-01

    A high resolution luminescence study of NaLaF 4: 1%Pr 3+, 5%Yb 3+ and NaLaF 4: 1%Ce 3+, 5%Yb 3+ in the UV to NIR spectral range using a InGaAs detector and a fourier transform interferometer is reported. Although the Pr 3+( 3P 0 → 1G 4), Yb 3+( 2F 7/2 → 2F 5/2) energy transfer step takes place, significant Pr 3+1G 4 emission around 993, 1330 and 1850 nm is observed. No experimental proof for the second energy transfer step in the down-conversion process between Pr 3+ and Yb 3+ can be given. In the case of NaLaF 4: Ce 3+, Yb 3+ it is concluded that the observed Yb 3+ emission upon Ce 3+ 5d excitation is the result of a charge transfer process instead of down-conversion.

  6. GROUND-BASED NEAR-INFRARED EMISSION SPECTROSCOPY OF HD 189733B

    SciTech Connect

    Waldmann, I. P.; Tinetti, G.; Drossart, P.; Swain, M. R.; Deroo, P.; Griffith, C. A.

    2012-01-01

    We investigate the K- and L-band dayside emission of the hot-Jupiter HD 189733b with three nights of secondary eclipse data obtained with the SpeX instrument on the NASA Infrared Telescope Facility. The observations for each of these three nights use equivalent instrument settings and the data from one of the nights have previously been reported by Swain et al. We describe an improved data analysis method that, in conjunction with the multi-night data set, allows increased spectral resolution (R {approx} 175) leading to high-confidence identification of spectral features. We confirm the previously reported strong emission at {approx}3.3 {mu}m and, by assuming a 5% vibrational temperature excess for methane, we show that non-LTE emission from the methane {nu}{sub 3} branch is a physically plausible source of this emission. We consider two possible energy sources that could power non-LTE emission and additional modeling is needed to obtain a detailed understanding of the physics of the emission mechanism. The validity of the data analysis method and the presence of strong 3.3 {mu}m emission are independently confirmed by simultaneous, long-slit, L-band spectroscopy of HD 189733b and a comparison star.

  7. Fluorescence excitation-emission matrix spectroscopy as a tool for determining quality of sparkling wines.

    PubMed

    Elcoroaristizabal, Saioa; Callejón, Raquel M; Amigo, Jose M; Ocaña-González, Juan A; Morales, M Lourdes; Ubeda, Cristina

    2016-09-01

    Browning in sparkling wines was assessed by the use of excitation-emission fluorescence spectroscopy combined with PARAllel FACtor analysis (PARAFAC). Four different cava sparkling wines were monitored during an accelerated browning process and subsequently storage. Fluorescence changes observed during the accelerated browning process were monitored and compared with other conventional parameters: absorbance at 420nm (A420) and the content of 5-hydroxymethyl-2-furfural (5-HMF). A high similarity of the spectral profiles for all sparkling wines analyzed was observed, being explained by a four component PARAFAC model. A high correlation between the third PARAFAC factor (465/530nm) and the commonly used non-enzymatic browning indicators was observed. The fourth PARAFAC factor (280/380nm) gives us also information about the browning process following a first order kinetic reaction. Hence, excitation-emission fluorescence spectroscopy, together with PARAFAC, provides a faster alternative for browning monitoring to conventional methods, as well as useful key indicators for quality control.

  8. Investigation of microplasma discharge in sea water for optical emission spectroscopy

    NASA Astrophysics Data System (ADS)

    Gamaleev, Vladislav; Okamura, Yo; Kitamura, Kensuke; Hashimoto, Yusuke; Oh, Jun-Seok; Furuta, Hiroshi; Hatta, Akimitsu

    2016-07-01

    Microplasma discharge in sea water for optical emission spectroscopy was investigated using a needle-to-plane electrode system. The electrodes of a Pd needle and a Pt plate were placed with a gap of 25 µm in typical artificial sea water or locally sampled natural deep sea water. A pulse current source, consisting of a MOSFET switch, a capacitor, an inductor and the resistance of the sea water between the electrodes, was used. The circuit parameters were optimized to decrease the breakdown voltage and the spark duration to suppress erosion of the electrodes. Using a microgap configuration, spark discharges were reproducibly ignited in the highly conductive sea water at low breakdown voltages. The ignition of spark discharges required not only a critical voltage sufficient for breakdown, but also a critical energy for preheating of the sea water, sufficient for bubble formation. The possibility of using optical emission spectroscopy of microplasma in water is shown for identifying elemental composition of sea water.

  9. The optical emission spectroscopy of pulsed and pulse- periodic discharges initiated with runaway electrons

    NASA Astrophysics Data System (ADS)

    Lomaev, M.; Sorokin, D.; Tarasenko, V.

    2015-11-01

    We report on the results of measurements of an electron Te and a gas Tg temperatures as well as a reduced electric field strength E/N in the plasma of a high-voltage nanosecond discharge initiated with runaway electrons in a gap with a strongly nonuniform electric field distribution. The foregoing plasma parameters were determined with optical emission spectroscopy techniques. The possibility of using the method for determining Te and E/N in thermodynamically nonequilibrium plasma, which is based on a determination of a ratio of a peak intensities of the ionic (λ = 391.4 nm) and molecular N2 (λ = 394 nm) nitrogen bands, is proved. To measure a gas temperature the optical emission spectroscopy technique based on the measurement of a relative radiation intensity of rotation structure of electronic-vibrational molecular transitions was used, as well.

  10. A CAVITY RING-DOWN SPECTROSCOPY MERCURY CONTINUOUS EMISSION MONITOR

    SciTech Connect

    Christopher C. Carter

    2003-09-30

    The work performed during this quarter by SRD scientists and engineers focused on a number of tasks. The initial acquisition of some hardware needed and the actual construction of the sampling system have begun. This sampling system will contain the pyrolysis oven to atomize the sample gas stream needed for total gaseous mercury measurements, the CRD cavity to acquire the ring-down signal needed to obtain the mercury concentration, various tubing, and temperature and pressure measurement equipment. The amount of tubing and valves have been cut to a minimum to try and reduce the resident time the sample flue gas stream is in the sampling system and minimize the possibility that the gases in the sample gas stream will react with the elements of the sampling system and change the component mixture contained in the flue gas. In an effort to minimize the equipment that needs to be close to the actual sampling port, SRD scientists decided to fiber optically couple the laser to the CRD cavity. However, the ultra-violet (UV) light needed for the mercury transition presents a problem as fiber optics can be solarized by the UV radiation thereby changing the transmission characteristics. SRD has obtained a solarization-resistant fiber. SRD scientists were then able to couple the UV laser light into the fiber and inject the output of the fiber into the CRD cavity and obtain a ring-down signal. Long-term effects of the UV radiation on the fiber optic are being monitored to detect any change in the transmission of the laser light to the cavity. Additional requirements of the mercury CRD monitor will be to not only monitor the mercury concentration continuously but also perform the measurements over extended periods of time. SRD has extended some previously performed shorter-term studies to longer time intervals. The results of these initial long-term studies are very promising.

  11. Metallic transfer between metals in sliding contact examined by auger emission spectroscopy

    NASA Technical Reports Server (NTRS)

    Pepper, S. V.

    1972-01-01

    Metallic transfer between polycrystalline metals in sliding contact was examined. Hemispherical riders of iron, nickel, and cobalt were slid on tungsten, tantalum, niobium, and molybdenum disks in ultrahigh vacuum. Auger emission spectroscopy was used to monitor the elemental composition of the disk surfaces. Iron, nickel, and cobalt transferred to tungsten, whereas only cobalt transferred to tantalum, niobium, and molybdenum. The results of this investigation are discussed in terms of the cohesive energy and strain hardening characteristics of the specimen materials.

  12. Characterization of dissolved organic matter in fogwater by excitation-emission matrix fluorescence spectroscopy

    USGS Publications Warehouse

    Birdwell, J.E.; Valsaraj, K.T.

    2010-01-01

    Dissolved organic matter (DOM) present in fogwater samples collected in southeastern Louisiana and central-eastern China has been characterized using excitation-emission matrix fluorescence spectroscopy. The goal of the study was to illustrate the utility of fluorescence for obtaining information on the large fraction of organic carbon in fogwaters (typically >40% by weight) that defies characterization in terms of specific chemical compounds without the difficulty inherent in obtaining sufficient fogwater volume to isolate DOM for assessment using other spectroscopic and chemical analyses. Based on the findings of previous studies using other characterization methods, it was anticipated that the unidentified organic carbon fraction would have characteristic peaks associated with humic substances and fluorescent amino acids. Both humic- and protein-like fluorophores were observed in the fogwater spectra and fluorescence-derived indices for the fogwater had similar values to those of soil and sediment porewater. Greater biological character was observed in samples with higher organic carbon concentrations. Fogwaters are shown to contain a mixture of terrestrially- and microbially-derived fluorescent organic material, which is expected to be derived from an array of different sources, such as suspended soil and dust particles, biogenic emissions and organic substances generated by atmospheric processes. The fluorescence results indicate that much of the unidentified organic carbon present in fogwater can be represented by humic-like and biologically-derived substances similar to those present in other aquatic systems, though it should be noted that fluorescent signatures representative of DOM produced by atmospheric processing of organic aerosols may be contributing to or masked by humic-like fluorophores. ?? 2010.

  13. A CAVITY RING-DOWN SPECTROSCOPY MERCURY CONTINUOUS EMISSION MONITOR

    SciTech Connect

    Christopher C. Carter

    2002-12-31

    SRD tested a number of different length cavities during this past quarter. Continuous transmission was observed with cavity lengths from 65 to 12 cm. The 65 cm cavity was replaced with a 39 cm cavity for work performed during this quarter. Flue gas components were tested for background absorptions and any interference with the determination of accurate mercury concentrations. Sulfur dioxide was found to absorb fairly strongly in the region of the mercury transition, but the Cavity Ring-Down (CRD) instrument was still able to detect mercury at subparts-per-billion by volume (ppb) levels. Additional flue gases tested included H{sub 2}O, CO, CO{sub 2}, NO, NO{sub 2}. None of these flue gas constituents showed any observable absorption in the ultraviolet region near the atomic mercury transition. Work was also initiated in speciation studies. In particular mercury chloride (HgCl{sub 2}) was tested. A mercury signal was detected from a gas stream containing HgCl{sub 2}. SRD was not able to determine definitively if there exists a spectral shift great enough to separate HgCl{sub 2} from elemental mercury in these initial tests.

  14. Low-energy electro- and photo-emission spectroscopy of GaN materials and devices

    SciTech Connect

    Piccardo, Marco; Weisbuch, Claude; Iveland, Justin; Nakamura, Shuji; Speck, James S.; Martinelli, Lucio Peretti, Jacques; Choi, Joo Won

    2015-03-21

    In hot-electron semiconductor devices, carrier transport extends over a wide range of conduction states, which often includes multiple satellite valleys. Electrical measurements can hardly give access to the transport processes over such a wide range without resorting to models and simulations. An alternative experimental approach however exists which is based on low-energy electron spectroscopy and provides, in a number of cases, very direct and selective information on hot-electron transport mechanisms. Recent results obtained in GaN crystals and devices by electron emission spectroscopy are discussed. Using near-band-gap photoemission, the energy position of the first satellite valley in wurtzite GaN is directly determined. By electro-emission spectroscopy, we show that the measurement of the electron spectrum emitted from a GaN p-n junction and InGaN/GaN light-emitting diodes (LEDs) under electrical injection of carriers provides a direct observation of transport processes in these devices. In particular, at high injected current density, high-energy features appear in the electro-emission spectrum of the LEDs showing that Auger electrons are being generated in the active region. These measurements allow us identifying the microscopic mechanism responsible for droop which represents a major hurdle for widespread adoption of solid-state lighting.

  15. Depth-Resolved X-ray Absorption Spectroscopy by Means of Grazing Emission X-ray Fluorescence.

    PubMed

    Kayser, Yves; Sá, Jacinto; Szlachetko, Jakub

    2015-11-03

    Grazing emission X-ray fluorescence (GEXRF) is well suited for nondestructive elemental-sensitive depth-profiling measurements on samples with nanometer-sized features. By varying the grazing emission angle under which the X-ray fluorescence signal is detected, the probed depth range can be tuned from a few to several hundred nanometers. The dependence of the XRF intensity on the grazing emission angle can be assessed in a sequence of measurements or in a scanning-free approach using a position-sensitive area detector. Hereafter, we will show that the combination of scanning-free GEXRF and fluorescence detected X-ray absorption spectroscopy (XAS) allows for depth-resolved chemical speciation measurements with nanometer-scale accuracy. While the conventional grazing emission geometry is advantageous to minimize self-absorption effects, the use of a scanning-free setup makes the sequential scanning of the grazing emission angles obsolete and paves the way toward time-resolved depth-sensitive XAS measurements. The presented experimental approach was applied to study the surface oxidation of an Fe layer on the top of bulk Si and of a Ge bulk sample. Thanks to the penetrating properties and the insensitivity toward the electric conduction properties of the incident and emitted X-rays, the presented experimental approach is well suited for in situ sample surface studies in the nanometer regime.

  16. Studies of atmospheric molecules by multiphoton spectroscopy

    SciTech Connect

    Johnson, P.M.

    1991-10-01

    Carbon dioxide presents a great challenge to spectroscopy because of its propensity toward dissociation in all of its excited states. Multiphoton ionization spectroscopy is usually not applicable to the study of dissociating molecules because the dissociation competes effectively with ionization, resulting in no signal. We reasoned, however, that with high enough laser fluence, ionization could compete with dissociation in the longer lived states, exposing them for study from the continuous spectral background resulting from rapidly dissociating states. We describe the various spectroscopic and photophysical effects found through the multiphoton ionization and multiphoton photoelectron spectra. A recently developed variant of threshold ionization spectroscopy, usually called ZEKE, has shown a great deal of usefulness in providing the same information as traditional photoelectron spectroscopy but with higher resolution and much better signal-to-noise when using standard laboratory lasers. Threshold ionization techniques locate the states of an ion by scanning a light source across the ionization continuum of a neutral and somehow detecting when electrons are produced with no kinetic energy. We chose to develop our capabilities in threshold ionization spectroscopy using aromatic molecules because of their importance and because their electronic structure allows a pump-probe type of excitation scheme which avoids the use of vacuum ultraviolet laser beams. Among aromatics, the azines are noted for their small S{sub 1}-T{sub 1} energy gap which give them unique and interesting photophysical properties. We have continued our work on the multiphoton spectrum of metastable nitrogen produced by an electric discharge in supersonic beam. We have been able to assign more of the lines and simulated their rotational structure but many peaks remain unassigned.

  17. Application of emission ( 57Co) Mössbauer spectroscopy in bioscience

    NASA Astrophysics Data System (ADS)

    Kamnev, Alexander A.

    2005-06-01

    Cobalt is an essential trace element with a broad range of physiological and biochemical functions. However, biochemical speciation of cobalt and structural investigations of cobalt-containing complexes with biomacromolecules are challenging, as the participation of cobalt in physiological processes is limited by its very low concentrations. Emission Mössbauer spectroscopy (EMS), with the radioactive 57Co isotope as the most widely used nuclide, is several orders of magnitude more sensitive than its 57Fe absorption variant which has had a rich history of applications in bioscience. Nevertheless, owing to specific difficulties related to the necessity of using radioactive 57Co in samples under study, applications of EMS in biological fields have so far been sparse. In this communication, the EMS applicability to studying biological objects as well as some specific aspects of the EMS methodology are considered in order to draw attention to the unique structural information which can be obtained non-destructively in situ. Chemical consequences (after-effects) of the nuclear transition ( 57Co→ 57Fe), which provide additional information on the electron acceptor properties of the proximate chemical microenvironment of the metal ions, are also considered. The data presented demonstrate that EMS is a sensitive tool for monitoring the chemical state and coordination of cobalt species in biological matter and in biomacromolecular complexes (metalloenzymes), providing valuable structural information at the atomic level.

  18. Time of flight emission spectroscopy of laser produced nickel plasma: Short-pulse and ultrafast excitations

    SciTech Connect

    Smijesh, N.; Chandrasekharan, K.; Joshi, Jagdish C.; Philip, Reji

    2014-07-07

    We report the experimental investigation and comparison of the temporal features of short-pulse (7 ns) and ultrafast (100 fs) laser produced plasmas generated from a solid nickel target, expanding into a nitrogen background. When the ambient pressure is varied in a large range of 10⁻⁶Torr to 10²Torr, the plume intensity is found to increase rapidly as the pressure crosses 1 Torr. Time of flight (TOF) spectroscopy of emission from neutral nickel (Ni I) at 361.9 nm (3d⁹(²D) 4p → 3d⁹(²D) 4s transition) reveals two peaks (fast and slow species) in short-pulse excitation and a single peak in ultrafast excitation. The fast and slow peaks represent recombined neutrals and un-ionized neutrals, respectively. TOF emission from singly ionized nickel (Ni II) studied using the 428.5 nm (3p⁶3d⁸(³P) 4s→ 3p⁶3d⁹ 4s) transition shows only a single peak for either excitation. Velocities of the neutral and ionic species are determined from TOF measurements carried out at different positions (i.e., at distances of 2 mm and 4 mm, respectively, from the target surface) on the plume axis. Measured velocities indicate acceleration of neutrals and ions, which is caused by the Coulomb pull of the electrons enveloping the plume front in the case of ultrafast excitation. Both Coulomb pull and laser-plasma interaction contribute to the acceleration in the case of short-pulse excitation. These investigations provide new information on the pressure dependent temporal behavior of nickel plasmas produced by short-pulse and ultrafast laser pulses, which have potential uses in applications such as pulsed laser deposition and laser-induced nanoparticle generation.

  19. Plasma emission spectroscopy for operating and developing the Spallation Neutron Source (SNS) H- ion sources

    SciTech Connect

    Han, Baoxi; Welton, Robert F; Murray Jr, S N; Pennisi, Terry R; Santana, Manuel; Stockli, Martin P

    2014-01-01

    An RF-driven, Cs-enhanced H- ion source feeds the SNS accelerator with a high current (typically >50 mA), ~1.0 ms pulsed beam at 60 Hz. To achieve the persistent high current beam for several weeks long service cycles, each newly installed ion source undergoes a rigorous conditioning and cesiation processes. Plasma conditioning outgases the system and sputter-cleans the ion conversion surfaces. A cesiation process immediately following the plasma conditioning releases Cs to provide coverage on the ion conversion surfaces. The effectiveness of the ion source conditioning and cesiation is monitored with plasma emission spectroscopy using a high-sensitivity optical spectrometer. Plasma emission spectroscopy is also used to provide a mean for diagnosing and confirming a failure of the insulating coating of the ion source RF antenna which is immersed in the plasma. Emissions of composition elements of the antenna coating material, Na emission being the most significant, drastically elevate to signal a failure when it happens. Plasma spectra of the developmental ion source with an AlN chamber and an external RF antenna are also briefly discussed.

  20. Tomographic optical emission spectroscopy of a high enthalpy air plasma flow.

    PubMed

    Hermann, Tobias; Löhle, Stefan; Fasoulas, Stefanos; Andrianatos, Andreas

    2016-12-20

    A method is presented allowing for locally resolved emission spectroscopy using a tomographic setup. The approach presented in this work is applied to a high enthalpy air plasma flow. The resulting data sets allow for a three-dimensional (3D) representation of the non-symmetric flow field using photographs of the test section and 2D representation of the spectrally resolved radiance of the flow field. An analysis of different exposure times shows that transient fluctuations of the plasma can result in substantial asymmetry that approaches symmetry only for longer exposure times when the temporal averaging of the emission is significant. The spectral data allows the analysis of species selective excitation and emission. A non-equilibrium between atomic and molecular excitation temperatures is concluded for the investigated air plasma flow field. The spatial distribution of atomic electronic excitation temperatures are close to rotational symmetry while molecular rotational and vibrational temperatures exhibit asymmetric behavior.

  1. Spatially resolved optical-emission spectroscopy of a radio-frequency driven iodine plasma source

    NASA Astrophysics Data System (ADS)

    Dedrick, James; Doyle, Scott; Grondein, Pascaline; Aanesland, Ane

    2016-09-01

    Iodine is of interest for potential use as a propellant for spacecraft propulsion, and has become attractive as a replacement to xenon due to its similar mass and ionisation potential. Optical emission spectroscopy has been undertaken to characterise the emission from a low-pressure, radio-frequency driven inductively coupled plasma source operating in iodine with respect to axial distance across its transverse magnetic filter. The results are compared with axial profiles of the electron temperature and density for identical source conditions, and the spatial distribution of the emission intensity is observed to be closely correlated with the electron temperature. This work has been done within the LABEX Plas@Par project, and received financial state aid managed by the ``Agence Nationale de la Recherche'', as part of the ``Programme d'Investissements d'Avenir'' under the reference ANR-11-IDEX-0004-02.

  2. Two-dimensional space-resolved emission spectroscopy of laser ablation plasma in water

    SciTech Connect

    Matsumoto, Ayumu; Tamura, Ayaka; Fukami, Kazuhiro; Ogata, Yukio H.; Sakka, Tetsuo

    2013-02-07

    We developed a method for two-dimensional space-resolved emission spectroscopy of laser-induced plasma in water to investigate the spatial distribution of atomic species involved in the plasma. Using this method, the laser ablation plasma produced on a Cu target in 5 mM NaCl aqueous solution was examined. The emission spectrum varied considerably depending on the detecting position. The temperature and the atomic density ratio N{sub Na}/N{sub Cu} at various detecting positions were evaluated by fitting emission spectra to a theoretical model based on the Boltzmann distribution. We are successful in observing even a small difference between the distributions of the plasma parameters along the directions vertical and horizontal to the surface. The present approach gives direct information for sound understanding of the behavior of laser ablation plasma produced on a solid surface in water.

  3. Perturbation Facilitated Dispersed Fluorescence and Stimulated Emission Pumping Spectroscopies of HCP

    NASA Astrophysics Data System (ADS)

    Ishikawa, Haruki; Muramoto, Yasuhiko; Namai, Masahito; Mikami, Naohiko

    2011-06-01

    Perturbations among molecular rovibronic levels provide us with mainly two benefits. Perturbations themselves are characteristic features of structure and dynamics of molecules. We have been investigating dynamics of highly excited vibrational levels of HCP in the tilde{X} ^1Σ^+ state by dispersed fluorescence (DF) and stimulated emission pumping (SEP) spectroscopies of the tilde{C} ^1A^' - tilde{X} ^1Σ^+ transition. In the case of tilde{X} ^1Σ^+ HCP, its vibrational dynamics is well described by the Fermi resonance between the bend and the CP stretch modes. Based on the analysis of the Fermi resonance, we have succeeded in revealing the change in character of the bending motion in highly excited vibrational levels. In addition, perturbations enable us to explore rovibrational levels into much wider region that cannot be accessed under limits of selection rules. Jacobson and Child showed that the Coriolis interaction becomes very strong in the highly excited levels near and the above the CPH barrier. For the experimental confirmation of their prediction, the observation of the VCH≠0 and the ℓ'' ≠ 0 levels are necessary. However, due to the selection rules and the Franck-Condon selectivity, only the VCH=0 and the ℓ''=0 levels had been observed. In the course of our study, we have found a perturbed level in the tilde{C} state. In general, a very clear even-v_2 progression appears in the DF spectra of HCP. However, in the DF spectra measured by using the perturbed level as the intermediate both the odd- and even-v_2 levels are observed. Moreover, several VCH=1 levels are observed in the spectra. The perturbation-facilitated DF and SEP spectroscopies are very powerful tools to exploring the highly excited vibrational levels of HCP. Details of the perturbation-facilitated DF and SEP spectroscopies are presented in the paper. H. Ishikawa, et al. J. Chem. Phys. 109, 492 (1998); H. Ishikawa, et al. Annu. Rev. Phys. Chem. 50, 443 (1999). M. P. Jacobson and M. S

  4. Soft-x-ray spectroscopy study of nanoscale materials

    SciTech Connect

    Guo, J.-H.

    2005-07-30

    The ability to control the particle size and morphology of nanoparticles is of crucial importance nowadays both from a fundamental and industrial point of view considering the tremendous amount of high-tech applications. Controlling the crystallographic structure and the arrangement of atoms along the surface of nanostructured material will determine most of its physical properties. In general, electronic structure ultimately determines the properties of matter. Soft X-ray spectroscopy has some basic features that are important to consider. X-ray is originating from an electronic transition between a localized core state and a valence state. As a core state is involved, elemental selectivity is obtained because the core levels of different elements are well separated in energy, meaning that the involvement of the inner level makes this probe localized to one specific atomic site around which the electronic structure is reflected as a partial density-of-states contribution. The participation of valence electrons gives the method chemical state sensitivity and further, the dipole nature of the transitions gives particular symmetry information. The new generation synchrotron radiation sources producing intensive tunable monochromatized soft X-ray beams have opened up new possibilities for soft X-ray spectroscopy. The introduction of selectively excited soft X-ray emission has opened a new field of study by disclosing many new possibilities of soft X-ray resonant inelastic scattering. In this paper, some recent findings regarding soft X-ray absorption and emission studies of various nanostructured systems are presented.

  5. Mid-infrared, long wave infrared (4-12 μm) molecular emission signatures from pharmaceuticals using laser-induced breakdown spectroscopy (LIBS).

    PubMed

    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.

  6. Fluorescence excitation-emission matrix spectroscopy analysis of landfill leachate DOM in coagulation-flocculation process.

    PubMed

    Zhu, Guocheng; Wang, Chuang; Dong, Xingwei

    2016-09-29

    Landfill leachate contains a variety of organic matters, some of which can be excited and emit fluorescence signal. In order to degrade these organic matters, the pretreatment of the leachate is needed, which can improve the degradation performance of post-treatment process. Coagulation-flocculation is one of the important pretreatment processes to treat landfill leachate. Assessing the chemical compositions of landfill leachate is helpful in the understanding of their sources and fates as well as the mechanistic behaviors in the water environment. The present work aimed to use fluorescence excitation-emission matrix spectroscopy (EEMs) to characterize the chemical fractions of landfill leachate dissolved organic matter (DOM) in conjunction with parallel factor analysis (PARAFAC). Results showed that the DOM of landfill leachate tested in this study was identified resulting from microbial input, which included five typical characteristic peaks and four kinds of PARAFAC fractions. These fractions were mainly composed of hydrophobic macromolecule humic acid-like (HM-HA), hydrophilic intermediate molecular fulvic acid-like (HIM-FA), and hydrophilic small molecule protein-like substances (HSM-PS). HM-HA and HIM-FA were found to be easier to remove than HSM-PS. Further research on HSM-PS removal by coagulation-flocculation still needs to be improved.

  7. Characterization of an atmospheric helium plasma jet by relative and absolute optical emission spectroscopy

    NASA Astrophysics Data System (ADS)

    Xiong, Qing; Nikiforov, Anton Yu; González, Manuel Á.; Leys, Christophe; Pei Lu, Xin

    2013-02-01

    The characteristics of plasma temperatures (gas temperature and electron excitation temperature) and electron density in a pulsed-dc excited atmospheric helium plasma jet are studied by relative and absolute optical emission spectroscopy (OES). High-resolution OES is performed for the helium and hydrogen lines for the determination of electron density through the Stark broadening mechanism. A superposition fitting method composed of two component profiles corresponding to two different electron densities is developed to fit the investigated lines. Electron densities of the orders of magnitude of 1021 and 1020 m-3 are characterized for the center and edge regions in the jet discharge when the applied voltage is higher than 13.0 kV. The atomic state distribution function (ASDF) of helium demonstrates that the discharge deviates from the Boltzmann-Saha equilibrium state, especially for the helium lower levels, which are significantly overpopulated. Local electron excitation temperatures T13 and Tspec corresponding to the lower and upper parts of the helium ASDF are defined and found to range from 1.2 eV to 1.4 eV and 0.2 eV to 0.3 eV, respectively. A comparative analysis shows that the Saha balance is valid in the discharge for helium atoms at high excited states.

  8. Finding the Elusive Iodocarbene: Fluorescence Excitation and Single Vibronic Level Emission Spectroscopy of Chi

    NASA Astrophysics Data System (ADS)

    Tao, C.; Ebben, C.; Ko, H. T.; Reid, S. A.; Wang, Z.; Sears, T. J.

    2009-06-01

    Among the triatomic halocarbenes, only the iodocarbenes remain to be characterized. The search for these elusive species is motivated by a controversy regarding the multiplicity of the ground state. Photoelectron spectra of Lineberger and co-workers suggest a triplet ground state for CHI, at variance with recent ab initio studies, which suggest a singlet ground state with a singlet-triplet gap of around 4 kcal mol^{-1}. In this work, we have succeeded in finding the spectra of CHI and its deuterated isotopomer using pulsed discharge jet spectroscopy. Rotationally resolved fluorescence excitation spectra are consistent with a singlet-singlet transition, and the derived rotational constants are in good agreement with theoretical predictions. Single vibronic level emission spectra confirm a singlet multiplicity for the ground state, and reveal extensive mixing of the singlet and triplet levels at higher energy. We are able to set a lower limit on the singlet-triplet gap of 4.1 kcal mol^{-1}, in excellent agreement with theory. Extrapolation of the observed bending levels for CHI and CDI to a common origin suggests that the origin of the A^{1}A^'' state lies near 10 500 cm^{-1}, and we will report on high resolution measurements near the electronic origin made at Brookhaven National Laboratory. M. K. Gilles, K. M. Ervin, J. Ho, and W. C. Lineberger, J. Phys. Chem. 96, 1130 (1992).

  9. Layer-Resolved Evolution of Organic Thin Films Monitored by Photoelectron Emission Microscopy and Optical Reflectance Spectroscopy

    PubMed Central

    2015-01-01

    Photoelectron emission microscopy (PEEM) and differential (optical) reflectance spectroscopy (DRS) have proven independently to be versatile analytical tools for monitoring the evolution of organic thin films during growth. In this paper, we present the first experiment in which both techniques have been applied simultaneously and synchronously. We illustrate how the combined PEEM and DRS results can be correlated to obtain an extended perspective on the electronic and optical properties of a molecular film dependent on the film thickness and morphology. As an example, we studied the deposition of the organic molecule α-sexithiophene on Ag(111) in the thickness range from submonolayers up to several monolayers. PMID:26523159

  10. Emission Spectroscopy of the 4X Source Discharge With and Without N2 Gas

    SciTech Connect

    Smith, Horace Vernon

    2016-01-14

    This tech note summarizes the December, 1988 emission spectroscopy measurements made on the 4X source discharge with and without N₂ gas added to the H + Cs discharge. This study is motivated by the desire to understand why small amounts of N₂ gas added to the source discharge results in a reduction in the H⁻ beam noise. The beneficial effect of N₂ gas on H⁻ beam noise was first discovered by Bill Ingalls and Stu Orbesen on the ATS SAS source. For the 4X source the observed effect is that when N2 gas is added to the discharge the H⁻ beam noise is reduced about a factor of 2.

  11. Soft X-ray emission spectroscopy of liquids and lithium batterymaterials

    SciTech Connect

    Augustsson, Andreas

    2004-01-01

    Lithium ion insertion into electrode materials is commonly used in rechargeable battery technology. The insertion implies changes in both the crystal structure and the electronic structure of the electrode material. Side-reactions may occur on the surface of the electrode which is exposed to the electrolyte and form a solid electrolyte interface (SEI). The understanding of these processes is of great importance for improving battery performance. The chemical and physical properties of water and alcohols are complicated by the presence of strong hydrogen bonding. Various experimental techniques have been used to study geometrical structures and different models have been proposed to view the details of how these liquids are geometrically organized by hydrogen bonding. However, very little is known about the electronic structure of these liquids, mainly due to the lack of suitable experimental tools. In this thesis examples of studies of lithium battery electrodes and liquid systems using soft x-ray emission spectroscopy will be presented. Monochromatized synchrotron radiation has been used to accomplish selective excitation, in terms of energy and polarization. The electronic structure of graphite electrodes has been studied, before and after lithium intercalation. Changes in the electronic structure upon lithiation due to transfer of electrons into the graphite π-bands have been observed. Transfer of electrons in to the 3d states of transition metal oxides upon lithiation have been studied, through low energy excitations as dd- and charge transfer-excitations. A SEI was detected on cycled graphite electrodes. By the use of selective excitation different carbon sites were probed in the SEI. The local electronic structure of water, methanol and mixtures of the two have been examined using a special liquid cell, to separate the liquid from the vacuum in the experimental chamber. Results from the study of liquid water showed a strong influence on the 3a1 molecular

  12. Ultrafast Time-Resolved Hard X-Ray Emission Spectroscopy on a Tabletop

    NASA Astrophysics Data System (ADS)

    Miaja-Avila, Luis; O'Neil, Galen C.; Joe, Young I.; Alpert, Bradley K.; Damrauer, Niels H.; Doriese, William B.; Fatur, Steven M.; Fowler, Joseph W.; Hilton, Gene C.; Jimenez, Ralph; Reintsema, Carl D.; Schmidt, Daniel R.; Silverman, Kevin L.; Swetz, Daniel S.; Tatsuno, Hideyuki; Ullom, Joel N.

    2016-07-01

    Experimental tools capable of monitoring both atomic and electronic structure on ultrafast (femtosecond to picosecond) time scales are needed for investigating photophysical processes fundamental to light harvesting, photocatalysis, energy and data storage, and optical display technologies. Time-resolved hard x-ray (>3 keV ) spectroscopies have proven valuable for these measurements due to their elemental specificity and sensitivity to geometric and electronic structures. Here, we present the first tabletop apparatus capable of performing time-resolved x-ray emission spectroscopy. The time resolution of the apparatus is better than 6 ps. By combining a compact laser-driven plasma source with a highly efficient array of microcalorimeter x-ray detectors, we are able to observe photoinduced spin changes in an archetypal polypyridyl iron complex [Fe (2 ,2'-bipyridine)3]2 + and accurately measure the lifetime of the quintet spin state. Our results demonstrate that ultrafast hard x-ray emission spectroscopy is no longer confined to large facilities and now can be performed in conventional laboratories with 10 times better time resolution than at synchrotrons. Our results are enabled, in part, by a 100- to 1000-fold increase in x-ray collection efficiency compared to current techniques.

  13. Role of the emission depth distribution function in quantification of electron spectroscopies

    NASA Astrophysics Data System (ADS)

    Jablonski, A.

    2005-07-01

    Quantitative analysis by Auger electron spectroscopy or photoelectron spectroscopy should be founded on a reliable relation between the measured signal intensity and composition of the surface region. In this relation, the signal electron elastic scattering effects are conveniently described by the emission depth distribution function (DDF). This function is the distribution of depths of origin for signal electrons emitted from a solid in a given direction without energy loss. Numerous parameters needed for quantification of electron spectroscopies can be derived from the DDF, e.g. the mean escape depth, the information depth, the effective attenuation length, etc. Generally, knowledge of the accurate DDF facilitates the procedure of including the elastic scattering effects into the formalism of quantitative analysis. The function called the partial escape distribution (PED) defining the probability of emission in a given direction after a certain number of inelastic interactions can be considered as a generalization of the DDF. The PED becomes equivalent to the DDF in the case of no inelastic interactions. A series of the PED functions is needed for quantification of the recorded spectra, especially when the elastic collisions need to be taken into account. It has been shown that the PED for any number of inelastic collisions can be derived from the DDF. Reliability of the obtained PED functions was checked for different analytical expressions for the DDF. It has been shown that the expression published by Tilinin et al. is the most accurate, and can be recommended for calculations of the PED.

  14. [Photodissociation of Acetylene and Acetone using Step-Scan Time-Resolved FTIR Emission Spectroscopy

    NASA Technical Reports Server (NTRS)

    McLaren, Ian A.; Wrobel, Jacek D.

    1997-01-01

    The photodissociation of acetylene and acetone was investigated as a function of added quenching gas pressures using step-scan time-resolved FTIR emission spectroscopy. Its main components consist of Bruker IFS88, step-scan Fourier Transform Infrared (FTIR) spectrometer coupled to a flow cell equipped with Welsh collection optics. Vibrationally excited C2H radicals were produced from the photodissociation of acetylene in the unfocused experiments. The infrared (IR) emission from these excited C2H radicals was investigated as a function of added argon pressure. Argon quenching rate constants for all C2H emission bands are of the order of 10(exp -13)cc/molecule.sec. Quenching of these radicals by acetylene is efficient, with a rate constant in the range of 10(exp -11) cc/molecule.sec. The relative intensity of the different C2H emission bands did not change with the increasing argon or acetylene pressure. However, the overall IR emission intensity decreased, for example, by more than 50% when the argon partial pressure was raised from 0.2 to 2 Torr at fixed precursor pressure of 160mTorr. These observations provide evidence for the formation of a metastable C2H2 species, which are collisionally quenched by argon or acetylene. Problems encountered in the course of the experimental work are also described.

  15. Emissions of methane and nitrous oxide from outdoor-stored broiler litter using tunable-diode laser spectroscopy

    NASA Astrophysics Data System (ADS)

    de Wit, William Harrison

    Handling and storage of a variety of types of agricultural wastes results in the formation and release of nitrous oxide (N2O) and methane (CH4) gases to the atmosphere. These gases contribute to climate change through the greenhouse effect. Few studies have examined evolution of these gases from stored poultry litter in North America. Although N 2O is a by-product of nitrification, it is largely produced as an intermediate product of denitrification and is produced most intensely when both aerobic and anaerobic conditions are present. CH4 emissions, however, are typically associated with anaerobic reactions. Outdoor storage of broiler litter provides an excellent media for which both aerobic and anaerobic zones can coexist, particularly when the litter is of varying ages from multiple broiler flocks (cycles). It provides a large amount of nitrogen for bacterial nitrification/denitrification processes as well as Carbon to support anaerobic bacterial fermentation. The objective of the study was to quantify N 2O and CH4 emissions for broiler litter stored in an uncovered, outdoor bunker by conducting small-scale dynamic flux chamber studies and full-scale field experiments. The field experiments used a modified micrometeorological mass balance approach to monitor emissions from stored broiler litter in a three-walled concrete bunker. Atmospheric concentrations of N2O and CH4 were measured using tunable-diode laser spectroscopy. Field experiments over the course of approximately four months yielded average emission rates of 14+/-17mug m-2 s -1 and 84+/-61 mug m-2 s-1 for N2O and CH4 respectively that agreed well with the trends of emission rates observed in the dynamic flux chamber experiments. The primary drivers of emissions of both CH4 and N2O appeared to be temperature and moisture content while organic carbon and organic nitrogen (loss on ignition, nitrate concentrations) contents were also important factors.

  16. Synthesis, structure, and emission spectroscopy of luminescent Pt(COD)(dithiolate) complexes

    SciTech Connect

    Bevilacqua, J.M.; Zuleta, J.A.; Eisenberg, R.

    1993-08-18

    The synthesis, characterization, X-ray structure determination and emission spectroscopy of two Pt(COD)(S-S) complexes are reported where COD = 1,5-cycloctadiene (COD) and S-S is maleonitriledithiolate (mnt) for complex 1 and 1-(ethoxycarbonyl)-1-cyanoethylene-2,2-dithiolate (ecda) for complex 2. Both complexes are isolated in high yield from the reaction of Pt(COD)Cl{sub 2} and the corresponding dianionic dithiolate salt. Orange crystals of 1 (C{sub 12}H{sub 12}N{sub 2}PtS{sub 2}) are monoclinic, space group P2{sub 1}/n (No. 14). Each complex possess a square planar structure with chelating diolefin and dithiolate ligands. Proton NMR spectroscopy shows that the solid-state structures are maintained in solution. The complexes are luminescent at low temperature in the solid state and in frozen glasses. In the solid state at 77 K, Pt(COD)(mnt) exhibits a highly structured emission ({lambda}{sub max} = 560 nm, 17.9 kcm{sup {minus}1}) with a vibronic progression of {approximately}1400 cm{sup {minus}1}, whereas for Pt(COD)(ecda), the emission is broad and featureless ({lambda}{sub max} = 525 nm, 19.0 kcm{sup {minus}1}). The emissive state for both complexes is assigned as a metal-to-dithiolate charge transfer with differences in the structure and energy of the emissions resulting from differences in the {pi}*{sub dithiolate} orbital of the mnt and ecda ligands.

  17. NATO Advanced Study Institute on Spectroscopy

    NASA Technical Reports Server (NTRS)

    DiBartolo, Baldassare; Barnes, James (Technical Monitor)

    2001-01-01

    This booklet presents an account of the course 'Spectroscopy of Systems with Spatially Confined Structures' held in Erice-Sicily, Italy, from June 15 to June 30, 2001. This meeting was organized by the International School of Atomic and Molecular Spectroscopy of the 'Ettore Majorana' Centre for Scientific Culture. The purpose of this course was to present and discuss nanometer-scale physics, a rapidly progressing field. The top-down approach of semiconductor technology will soon meet the scales of the bottom-up approaches of supramolecular chemistry and of spatially localized excitations in ionic crystals. This course dealt with the fabrication, measurement and understanding of the relevant structures and brought together the scientific communities responsible for these development. The advances in this area of physics have already let to applications in optoelectronics and will likely lead to many more. The subjects of the course included spatially resolved structures such as quantum wells, quantum wires and quantum dots, single atoms and molecules, clusters, fractal systems, and the development of related techniques like near-field spectroscopy and confocal microscopy to study such systems.

  18. Excitation-emission matrices and synchronous fluorescence spectroscopy for the diagnosis of gastrointestinal cancers

    NASA Astrophysics Data System (ADS)

    Genova, Ts; Borisova, E.; Penkov, N.; Vladimirov, B.; Zhelyazkova, A.; Avramov, L.

    2016-06-01

    We report the development of an improved fluorescence technique for cancer diagnostics in the gastrointestinal tract. We investigate the fluorescence of ex vivo colorectal (cancerous and healthy) tissue samples using excitation-emission matrix (EEM) and synchronous fluorescence spectroscopy (SFS) steady-state approaches. The obtained results are processed for revealing characteristic fluorescence spectral features with a valuable diagnostic meaning. The main tissue fluorophores, contributing to the observed fluorescence, are tyrosine, tryptophan, NADH, FAD, collagen and elastin. Based on the results of the Mann-Whitney test as useful parameters for differentiation of gastrointestinal cancer from normal mucosa, we suggest using excitation wavelengths in the range 300 - 360 nm for fluorescence spectroscopy and wavelengths intervals of 60 nm and 90 nm for SFS.

  19. Excitation-emission matrices (EEMs) and synchronous fluorescence spectroscopy (SFS) investigations of gastrointestinal tissues

    NASA Astrophysics Data System (ADS)

    Genova, Ts.; Borisova, E.; Zhelyazkova, Al.; Semyachkina-Glushkovskaya, O.; Penkov, N.; Keremedchiev, M.; Vladimirov, B.; Avramov, L.

    2015-01-01

    In this report we will present our recent investigations of the fluorescence properties of lower part gastrointestinal tissues using excitation-emission matrix and synchronous fluorescence spectroscopy measurement modalities. The spectral peculiarities observed will be discussed and the endogenous sources of the fluorescence signal will be addressed. For these fluorescence spectroscopy measurements the FluoroLog 3 system (HORIBA Jobin Yvon, France) was used. It consists of a Xe lamp (300 W, 200-650 nm), a double mono-chromators, and a PMT detector with a work region at 220- 850 nm. Autofluorescence signals were detected in the form of excitation-emission matrices for the samples of normal mucosa, dysphasia and colon carcinoma and specific spectral features for each tissue were found. Autofluorescence signals from the same samples are observed through synchronous fluorescence spectroscopy, which is a novel promising modality for fluorescence spectroscopy measurements of bio-samples. It is one of the most powerful techniques for multicomponent analysis, because of its sensitivity. In the SFS regime, the fluorescence signal is recorded while both excitation λexc and emission wavelengths λem are simultaneously scanned. A constant wavelength interval is maintained between the λexc and λem wavelengths throughout the spectrum. The resulted fluorescence spectrum shows narrower peak widths, in comparison with EEMs, which are easier for identification and minimizes the chance for false determinations or pretermission of specific spectral feature. This modality is also faster, than EEMs, a much smaller number of data points are required.1 In our measurements we use constant wavelength interval Δλ in the region of 10-200 nm. Measurements are carried out in the terms of finding Δλ, which results in a spectrum with most specific spectral features for comparison with spectral characteristics observed in EEMs. Implementing synchronous fluorescence spectroscopy in optical

  20. Ultrasensitive detection of waste products in water using fluorescence emission cavity-enhanced spectroscopy.

    PubMed

    Bixler, Joel N; Cone, Michael T; Hokr, Brett H; Mason, John D; Figueroa, Eleonora; Fry, Edward S; Yakovlev, Vladislav V; Scully, Marlan O

    2014-05-20

    Clean water is paramount to human health. In this article, we present a technique for detection of trace amounts of human or animal waste products in water using fluorescence emission cavity-enhanced spectroscopy. The detection of femtomolar concentrations of urobilin, a metabolic byproduct of heme metabolism that is excreted in both human and animal waste in water, was achieved through the use of an integrating cavity. This technique could allow for real-time assessment of water quality without the need for expensive laboratory equipment.

  1. Determination of Yttrium in High Density Silicon Nitride by Emission and X-Ray Fluorescence Spectroscopy.

    DTIC Science & Technology

    1981-08-01

    AD-AI07 596 ARMY MATERIALS AND MECHANICS RESEARCH CENTER WATERTOWN MA F/S 7/4 DETERMINATION OF YTTRIUM IN HIGH DENSITY SILICON NITRIDE BY EMI-ETCIU...AUG Al B H STRAUSS. UNCLASSIFIED AMMRC-TR-Al-39 N AMMRC TR 81-39 A ~LEVEL ’ t’- .- DETERMINATION OF YTTRIUM IN 1 HIGH DENSITY SILICON NITRIDE BY...DETERMINATION OF YTTRIUM IN HIGH DENSITY SILICON NITRIDE BY EMISSION AND X-RAY Final Report FLUORESCENCE SPECTROSCOPY 6 PERFORMING ORG. REPORT NUMBER 7. AUTHOR

  2. Physical Properties of Emission-Line Galaxies at 2 from Near-Infrared Spectroscopy with Magellan FIRE

    NASA Astrophysics Data System (ADS)

    Masters, Daniel C.; McCarthy, P. J.; Malkan, M. A.; Siana, B. D.; Scarlata, C.; Hathi, N. P.; Atek, H.; Henry, A. L.; WISP Team

    2014-01-01

    We present results from near-infrared spectroscopy with Magellan FIRE of 26 strong emission-line galaxies at 2.2 and 1.5. The sample was selected from the WFC3 Infrared Spectroscopic Parallels (WISP) survey, which uses the near-infrared grism capability of the Hubble Space Telescope Wide Field Camera 3 to detect emission-line galaxies over 0.5 < z < 2.3. High-resolution ( 5000) follow-up spectroscopy with Magellan FIRE over 1.0--2.5 microns resolves important rest-frame optical emission lines, allowing us to measure physical properties such as dust obscuration, metal abundance, star formation rate, ionization parameter, and emission line kinematics. We also analyze the properties of composite spectra derived from the FIRE-observed sample. With this relatively large sample of rest-frame optical spectra we can make statistical inferences about the population of emission-line galaxies at 2. We find that the galaxies are low metallicity ( 1/5-1/2 Z_solar) as determined from the R23 calibration. The galaxies are low dust extinction on average (E(B-V 0.2) but with significant scatter. The dust-corrected H-alpha star formation rates range from ~10--150 M_sun yr^-1 with a mean of 50 M_su yr^-1. The average ionization parameter for the sample, log U ~ -2.5, is higher than typically found for star-forming galaxies in the local universe but consistent with those found in more intense starbursting regions in galaxies such as M82. Emission line velocity dispersions are measured to be 71 +- 38 km s^-1, in good agreement with other studies that have probed the H-alpha kinematics of star-forming galaxies at similar redshift. The galaxies are compact, with half-light radii of < 2 kpc, and ~50% show evidence for multiple structures or asymmetries in the WFC3 imaging. Based on the line velocity dispersions and the location of the galaxies on BPT diagnostic plots, there is little evidence for significant AGN contribution to most emission-line galaxies at 2.

  3. Spatially resolved measurement of Ar excited species in magnetized inductively coupled plasma using multi-port optical emission spectroscopy

    NASA Astrophysics Data System (ADS)

    Kim, Yun-Gi; Ha, Chang-Seung; Han, Moon-Ki; Seo, Kwon-Sang; Kim, Dong-Hyun; Lee, Hae June; Lee, Ho-Jun; Koo, Il Gyo; Lee, Soojin; Seong, Hyo-Seong

    2013-09-01

    Optical emission spectrometry (OES), which is the spectral analysis of the light emanating from plasma, is probably the most widely used method for monitoring and diagnosis of plasma processes. This technique has the advantage of being external to the reactor and vacuum system. However, the OES method is limited to measure spatial distribution of species accurately. In this work, multi-port optical emission spectroscopy system was developed to improve the space-resolved ability. This multi-port OES system consists of Si wafers, optical fibers, prisms and windows. The Si wafers are used for making the same condition while this device is put in the etching or deposition reactor. The emission light from plasma is collected and transferred through the optical fibers. The spatial distribution of Ar excited species is measured using this device in inductively coupled plasma with and without external axial magnetic field. The off-axis density profile of electron, Ar ion and excited species are appeared in weakly magnetized inductively coupled plasma. Also the emission intensity was changed in this experimental condition. Two-dimensional simulation was studied to verify this experimental result. This was supported by SEMES cooperative research project.

  4. Thermal degradation of polyketones. Vibrational spectroscopy studies

    NASA Astrophysics Data System (ADS)

    Conti, G.; Sommazzi, A.

    1993-03-01

    Thermal degradation studies of regular alternating polymers of carbon monoxide and olefin have been followed by FT-IR spectroscopy. The I.R spectra of solid samples, performed in inert atmosphere and in high vacuum, were recorded as a function of time at different temperatures. From the I.R. data it is possible to conclude that the reaction process, near the melting point of the polymers, could consist of intra or intermolecular hydrogen transfer yielding an enol and a small quantity of insaturations. The thermal degradation process, at temperatures higher than melting point, involves the scission of the polymer chain and produces fragments with a large number of insaturations.

  5. Optical Emission Spectroscopy of an Atmospheric Pressure Plasma Jet During Tooth Bleaching Gel Treatment.

    PubMed

    Šantak, Vedran; Zaplotnik, Rok; Tarle, Zrinka; Milošević, Slobodan

    2015-11-01

    Optical emission spectroscopy was performed during atmospheric pressure plasma needle helium jet treatment of various tooth-bleaching gels. When the gel sample was inserted under the plasma plume, the intensity of all the spectral features increased approximately two times near the plasma needle tip and up to two orders of magnitude near the sample surface. The color change of the hydroxylapatite pastille treated with bleaching gels in conjunction with the atmospheric pressure plasma jet was found to be in correlation with the intensity of OH emission band (309 nm). Using argon as an additive to helium flow (2 L/min), a linear increase (up to four times) of OH intensity and, consequently, whitening (up to 10%) of the pastilles was achieved. An atmospheric pressure plasma jet activates bleaching gel, accelerates OH production, and accelerates tooth bleaching (up to six times faster).

  6. Time-resolved spectroscopy measurements of hydrogen-alpha, -beta, and -gamma emissions

    SciTech Connect

    Parigger, Christian G.; Dackman, Matthew; Hornkohl, James O

    2008-11-01

    Hydrogen emission spectroscopy results are reported following laser-induced optical breakdown with infrared Nd:YAG laser radiation focused into a pulsed methane flow. Measurements of Stark-broadened atomic hydrogen-alpha, -beta, and -gamma lines show electron number densities of 0.3 to 4x10{sup 17} cm{sup -3} for time delays of 2.1 to 0.4 {mu}s after laser-induced optical breakdown. In methane flow, recombination molecular spectra of the {delta}{nu}=+2 progression of the C2 Swan system are discernable in the H{beta} and H{gamma} plasma emissions within the first few microseconds. The recorded atomic spectra indicate the occurrence of hydrogen self-absorption for pulsed CH4 flow pressures of 2.7x10{sup 5} Pa (25 psig) and 6.5x10{sup 5} Pa (80 psig)

  7. Laser-induced optical breakdown spectroscopy of polymer materials based on evaluation of molecular emission bands

    NASA Astrophysics Data System (ADS)

    Trautner, Stefan; Jasik, Juraj; Parigger, Christian G.; Pedarnig, Johannes D.; Spendelhofer, Wolfgang; Lackner, Johannes; Veis, Pavel; Heitz, Johannes

    2017-03-01

    Laser-induced breakdown spectroscopy (LIBS) for composition analysis of polymer materials results in optical spectra containing atomic and ionic emission lines as well as molecular emission bands. In the present work, the molecular bands are analyzed to obtain spectroscopic information about the plasma state in an effort to quantify the content of different elements in the polymers. Polyethylene (PE) and a rubber material from tire production are investigated employing 157 nm F2 laser and 532 nm Nd:YAG laser ablation in nitrogen and argon gas background or in air. The optical detection reaches from ultraviolet (UV) over the visible (VIS) to the near infrared (NIR) spectral range. In the UV/VIS range, intense molecular emissions, C2 Swan and CN violet bands, are measured with an Echelle spectrometer equipped with an intensified CCD camera. The measured molecular emission spectra can be fitted by vibrational-rotational transitions by open access programs and data sets with good agreement between measured and fitted spectra. The fits allow determining vibrational-rotational temperatures. A comparison to electronic temperatures Te derived earlier from atomic carbon vacuum-UV (VUV) emission lines show differences, which can be related to different locations of the atomic and molecular species in the expanding plasma plume. In the NIR spectral region, we also observe the CN red bands with a conventional CDD Czerny Turner spectrometer. The emission of the three strong atomic sulfur lines between 920 and 925 nm is overlapped by these bands. Fitting of the CN red bands allows a separation of both spectral contributions. This makes a quantitative evaluation of sulfur contents in the start material in the order of 1 wt% feasible.

  8. Laser-induced optical breakdown spectroscopy of polymer materials based on evaluation of molecular emission bands.

    PubMed

    Trautner, Stefan; Jasik, Juraj; Parigger, Christian G; Pedarnig, Johannes D; Spendelhofer, Wolfgang; Lackner, Johannes; Veis, Pavel; Heitz, Johannes

    2017-03-05

    Laser-induced breakdown spectroscopy (LIBS) for composition analysis of polymer materials results in optical spectra containing atomic and ionic emission lines as well as molecular emission bands. In the present work, the molecular bands are analyzed to obtain spectroscopic information about the plasma state in an effort to quantify the content of different elements in the polymers. Polyethylene (PE) and a rubber material from tire production are investigated employing 157nmF2 laser and 532nm Nd:YAG laser ablation in nitrogen and argon gas background or in air. The optical detection reaches from ultraviolet (UV) over the visible (VIS) to the near infrared (NIR) spectral range. In the UV/VIS range, intense molecular emissions, C2 Swan and CN violet bands, are measured with an Echelle spectrometer equipped with an intensified CCD camera. The measured molecular emission spectra can be fitted by vibrational-rotational transitions by open access programs and data sets with good agreement between measured and fitted spectra. The fits allow determining vibrational-rotational temperatures. A comparison to electronic temperatures Te derived earlier from atomic carbon vacuum-UV (VUV) emission lines show differences, which can be related to different locations of the atomic and molecular species in the expanding plasma plume. In the NIR spectral region, we also observe the CN red bands with a conventional CDD Czerny Turner spectrometer. The emission of the three strong atomic sulfur lines between 920 and 925nm is overlapped by these bands. Fitting of the CN red bands allows a separation of both spectral contributions. This makes a quantitative evaluation of sulfur contents in the start material in the order of 1wt% feasible.

  9. Measuring NMHC and NMOG emissions from motor vehicles via FTIR spectroscopy

    NASA Astrophysics Data System (ADS)

    Gierczak, Christine A.; Kralik, Lora L.; Mauti, Adolfo; Harwell, Amy L.; Maricq, M. Matti

    2017-02-01

    The determination of non-methane organic gases (NMOG) emissions according to United States Environmental Protection Agency (EPA) regulations is currently a multi-step process requiring separate measurement of various emissions components by a number of independent on-line and off-line techniques. The Fourier transform infrared spectroscopy (FTIR) method described in this paper records all required components using a single instrument. It gives data consistent with the regulatory method, greatly simplifies the process, and provides second by second time resolution. Non-methane hydrocarbons (NMHCs) are measured by identifying a group of hydrocarbons, including oxygenated species, that serve as a surrogate for this class, the members of which are dynamically included if they are present in the exhaust above predetermined threshold levels. This yields an FTIR equivalent measure of NMHC that correlates within 5% to the regulatory flame ionization detection (FID) method. NMOG is then determined per regulatory calculation solely from FTIR recorded emissions of NMHC, ethanol, acetaldehyde, and formaldehyde, yielding emission rates that also correlate within 5% with the reference method. Examples are presented to show how the resulting time resolved data benefit aftertreatment development for light duty vehicles.

  10. Surface studies of praseodymium by electron spectroscopies

    NASA Astrophysics Data System (ADS)

    Krawczyk, Mirosław; Pisarek, Marcin; Lisowski, Wojciech; Jablonski, Aleksander

    2016-12-01

    Electron transport properties in praseodymium (Pr) foil samples were studied by elastic-peak electron spectroscopy (EPES). Prior to EPES measurements, the Pr sample surface was pre-sputtered by Ar ions with ion energy of 2-3 keV. After such treatment, the Pr sample still contained about 10 at.% of residual oxygen in the surface region, as detected by X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES) analyses. The inelastic mean free path (IMFP), characterizing electron transport within this region (4 nm-thick), was evaluated from EPES using both Ni and Au standards as a function of energy in the range of 0.5-2 keV. Experimental IMFPs, λ, were approximated by the simple function λ = kEp, where E is energy (in eV), and k = 0.1549 and p = 0.7047 were the fitted parameters. These values were compared with IMFPs for the praseodymium surface in which the presence of oxygen was tentatively neglected, and also with IMFPs resulting from the TPP-2M predictive equation for bulk praseodymium. We found that the measured IMFP values to be only slightly affected by neglect of oxygen in calculations. The fitted function applied here was consistent with the energy dependence of the EPES-measured IMFPs. Additionally, the measured IMFPs were found to be from 2% to 4.2% larger than the predicted IMFPs for praseodymium in the energy range of 500-1000 eV. For electron energies of 1500 eV and 2000 eV, there was an inverse correlation between these values, and then the resulting deviations of -0.4% and -2.7%, respectively, were calculated.

  11. Spectroscopy and single-molecule emission of a fluorene-terthiophene oligomer.

    PubMed

    Khalil, G E; Adawi, A M; Robinson, B; Cadby, A J; Tsoi, W C; Kim, J-S; Charas, A; Morgado, J; Lidzey, D G

    2011-10-27

    We study the thiophene-based oligomer poly[2,7-(9,9-bis(2'-ethylhexyl)fluorene)-alt-2,5-terthiophene] (PF3T) in solution and when dispersed at low concentration into a polynorbornene matrix. We find that at high concentration in solution the 0-0 electronic transition observed in fluorescence is suppressed, a result indicative of the formation of weakly coupled H-aggregates. At low concentration in a polymer matrix, emission from both single molecules and molecular aggregates is observed. We find that the fluorescence spectra of most PF3T emitters are composed of a number of relatively narrow emission features, indicating that the emission usually occurs from multiple chromophores. A small number of PF3T molecules are however characterized by single chromophore emission, spectral blinking, and narrowed emission peaks.

  12. Laser Induced Emission Spectroscopy of Cold and Isolated Neutral PAHs and PANH: Implications for the red rectangle emission

    NASA Astrophysics Data System (ADS)

    Bejaoui, Salma; Salama, Farid; Sciamma O'Brien, Ella

    2016-06-01

    Blue luminescence (BL) in the emission spectra of the red rectangle centered on the bright star HD44179 is recently reported by Vijh et al [1]. This results is consistent with the broad band polarization measurements obtained in 1980 by Schmidt et al. Both experimental and theoretical studies support that BL emission could be attributed the luminescence of Polycyclic Aromatic Hydrocarbon (PAH) excited with ultraviolet light from the center of the star [4 and reference therein]. The abundance on N to C in the interstellar medium suggest also that nitrogen substituted PAH (PANH) are likely abundant in the interstellar medium [3]. They exhibit similar features as PAHs and could contribute to the unidentified spectral bands. Comparing the BL to laboratory spectra obtained on similar environment is crucial for the identification of interstellar molecules. We present in this works the absorption and the laser induced emission spectra of several isolated and cold PAHs and PANHs. Laser induced emission was performed first to PAHs and PANHs isolated in Argon matrix at 10 K. Then, measurements are performed with the supersonic jet technique of the COSmIC laboratory facility at NASA Ames. We focus, here, on the emission spectra (fluorescence and (or) phosphorescence) of these molecules and we discuss their contributions to the blue luminescence emission in the Red Rectangle nebula.[1] Vijh,U.P., Witt. A.N. & Gordon,K.D, APJ, 606, L69 (2004)[2] Schmidt, G. D., Cohen, M. & Margon, B., ApJ, 239L.133S (1980)[3] Spitzer, L., Physical Processes in the Interstellar Medium (New York Wiley-Interscience) (1978)[4] Salama, F., Galazutdinov, G. A., Kre lowski, J., Allamandola, L. J., & Musaev, F. A. ApJ, 526,(1999)

  13. Development of Advanced Electrochemical Emission Spectroscopy for Monitoring Corrosion in Simulated DOE Liquid Waste

    SciTech Connect

    Digby Macdonald; Brian Marx; Balaji Soundararajan; Morgan Smith

    2005-07-28

    The different tasks that have been carried out under the current program are as follows: (1) Theoretical and experimental assessment of general corrosion of iron/steel in borate buffer solutions by using electrochemical impedance spectroscopy (EIS), ellipsometry and XPS techniques; (2) Development of a damage function analysis (DFA), which would help in predicting the accumulation of damage due to pitting corrosion in an environment prototypical of DOE liquid waste systems; (3) Experimental measurement of crack growth rate, acoustic emission signals, and coupling currents for fracture in carbon and low alloy steels as functions of mechanical (stress intensity), chemical (conductivity), electrochemical (corrosion potential, ECP), and microstructural (grain size, precipitate size, etc) variables in a systematic manner, with particular attention being focused on the structure of the noise in the current and its correlation with the acoustic emissions; (4) Development of fracture mechanisms for carbon and low alloy steels that are consistent with the crack growth rate, coupling current data and acoustic emissions; (5) Inserting advanced crack growth rate models for SCC into existing deterministic codes for predicting the evolution of corrosion damage in DOE liquid waste storage tanks; (6) Computer simulation of the anodic and cathodic activity on the surface of the steel samples in order to exactly predict the corrosion mechanisms; (7) Wavelet analysis of EC noise data from steel samples undergoing corrosion in an environment similar to that of the high level waste storage containers, to extract data pertaining to general, pitting and stress corrosion processes, from the overall data. The work has yielded a number of important findings, including an unequivocal demonstration of the role of chloride ion in passivity breakdown on nickel in terms of cation vacancy generation within the passive film, the first detection and characterization of individual micro fracture

  14. The time-dependent emission of molecular iodine from Laminaria Digitata measured with incoherent broadband cavity-enhanced absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Dixneuf, S.

    2009-04-01

    The release of molecular iodine (I2) from the oceans into the atmosphere has been recognized to correlate strongly with ozone depletion events and aerosol formation in the Marine Boundary Layer (MBL), which affects in turn global radiative forcing. The detailed mechanisms and dominant sources leading to the observed concentrations of I2 in the marine troposphere are still under intense investigation. In a recent campaign on the Irish west coast at Mace Head Atmospheric Research Station [1], it was found that significant levels of molecular iodine correlated with times of low tide, suggesting that the emission of air-exposed macro-algae may be a prime source of molecular iodine in coastal areas [2]. To further investigate this hypothesis we tried to detect the I2 emission of the brown seaweed Laminaria digitata, one of the most efficient iodine accumulators among living systems, directly by means of highly sensitive incoherent broadband cavity-enhanced absorption spectroscopy (IBBCEAS) [3]. IBBCEAS combines a good temporal and spatial resolution with high molecule-specific detection limits [4] comparable to that of typical LP-DOAS. IBBCEAS thus complements LP-DOAS in the search for sources of tropospheric trace gases. In this presentation the first direct observation of the time dependence of molecular iodine emission from Laminaria digitata will be shown. Plants were studied under naturally occurring stress for quasi in situ conditions for many hours. Surprisingly, the release of I2 occurs in short, strong bursts with quasi-oscillatory behaviour, bearing similarities to well known "iodine clock reactions". References [1] Saiz-Lopez A. & Plane, J. M. C. Novel iodine chemistry in the marine boundary layer. Geophys. Res. Lett. 31, L04112 (2004) doi:10.1029/2003GL019215. [2] McFiggans, G., Coe, H., Burgess, R., Allan, J., Cubison, M., Alfarra, M. R., Saunders, R., Saiz-Lopez, A., Plane, J. M. C., Wevill, D. J., Carpenter, L. J., Rickard, A. R. & Monks, P. S. Direct

  15. Capillary Electrophoresis and Fluorescence Excitation-Emission Matrix Spectroscopy for Characterization of Humic Substances

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Capillary electrophoresis (CE) and fluorescence spectroscopy have been used in natural organic matter (NOM) studies. In this study, we characterized five fulvic acids, six humic acids and two unprocessed NOM samples obtained from the International Humic Substances Society (IHSS) using these two ana...

  16. Emission Spectroscopy and Radiometric Measurements in the NASA Ames IHF Arc Jet Facility

    NASA Technical Reports Server (NTRS)

    Winter, Michael W.; Raiche, George A.; Prabhu, Dinesh K.

    2012-01-01

    Plasma diagnostic measurement campaigns in the NASA Ames Interaction Heating Facility (IHF) have been conducted over the last several years with a view towards characterizing the flow in the arc jet facility by providing data necessary for modeling and simulation. Optical emission spectroscopy has been used in the plenum and in the free jet of the nozzle. Radiation incident over a probe surface has also been measured using radiometry. Plenum measurements have shown distinct radial profiles of temperature over a range of operating conditions. For cases where large amounts of cold air are added radially to the main arc-heated stream, the temperature profiles are higher by as much as 1500 K than the profiles assumed in flow simulations. Optical measurements perpendicular to the flow direction in the free jet showed significant contributions to the molecule emission through inverse pre-dissociation, thus allowing determination of atom number densities from molecular emission. This has been preliminarily demonstrated with the N2 1st Positive System. Despite the use of older rate coefficients, the resulting atom densities are reasonable and surprisingly close to flow predictions.

  17. Turbine engine exhaust gas measurements using in-situ FT-IR emission/transmission spectroscopy

    NASA Astrophysics Data System (ADS)

    Marran, David F.; Cosgrove, Joseph E.; Neira, Jorge; Markham, James R.; Rutka, Ronald; Strange, Richard R.

    2001-02-01

    12 An advanced multiple gas analyzer based on in-situ Fourier transform infrared spectroscopy has been used to successfully measure the exhaust plume composition and temperature of an operating gas turbine engine at a jet engine test stand. The sensor, which was optically coupled to the test cell using novel broadband hollow glass waveguides, performed well in this harsh environment (high acoustical noise and vibration, considerable temperature swings in the ambient with engine operation), providing quantitative gas phase information. Measurements were made through the diameter of the engine's one meter exhaust plume, about 0.7 meters downstream of the engine exit plane. The sensor performed near simultaneous infrared transmission and infrared emission measurements through the centerline of the plume. Automated analysis of the emission and transmission spectra provided the temperature and concentration information needed for engine tuning and control that will ensure optimal engine operation and reduced emissions. As a demonstration of the utility and accuracy of the technique, carbon monoxide, nitric oxide, water, and carbon dioxide were quantified in spite of significant variations in the exhaust gas temperature. At some conditions, unburned fuel, particulates (soot/fuel droplets), methane, ethylene and aldehydes were identified, but not yet quantified.

  18. Corrosion Study Using Electrochemical Impedance Spectroscopy

    NASA Technical Reports Server (NTRS)

    Farooq, Muhammad Umar

    2003-01-01

    Corrosion is a common phenomenon. It is the destructive result of chemical reaction between a metal or metal alloy and its environment. Stainless steel tubing is used at Kennedy Space Center for various supply lines which service the orbiter. The launch pads are also made of stainless steel. The environment at the launch site has very high chloride content due to the proximity to the Atlantic Ocean. Also, during a launch, the exhaust products in the solid rocket boosters include concentrated hydrogen chloride. The purpose of this project was to study various alloys by Electrochemical Impedance Spectroscopy in corrosive environments similar to the launch sites. This report includes data and analysis of the measurements for 304L, 254SMO and AL-6XN in primarily neutral 3.55% NaCl. One set of data for 304L in neutral 3.55%NaCl + 0.1N HCl is also included.

  19. [Study on terahertz spectroscopy of Hotan jade].

    PubMed

    Maimaitiming; Ainiwaer; Xiong, Wei; Guo, Xue-jiao; Shen, Jing-ling

    2010-10-01

    Terahertz time-domain spectroscopy (THz-TDS) technique has a wide range of applications including illicit drugs and explosive detection, and organic molecules recognition. In the present paper, the spectral features of three kinds of Hotan jade were studied experimentally by THz-TDS technique and the characteristic absorption spectra and refractive index were obtained in the range of 0.2 to 2.6 THz. The experimental results show that different samples have different absorption characters, and the refractive index is 2.4-2.7 in the range of 0.2-2.6 THz. The results indicate that it is feasible to apply THz-TDS technique to identification of Hotan jade, which provides a new approach to the nondestructive examination of Hotan jade.

  20. Study of infrared emission spectroscopy for the B1Δg-A1Πu and B'1Σg+-A1Πu systems of C2

    NASA Astrophysics Data System (ADS)

    Chen, Wang; Kawaguchi, Kentarou; Bernath, Peter F.; Tang, Jian

    2016-02-01

    Thirteen bands for the B1Δg-A1Πu system and eleven bands for the B'1Σg+-A1Πu system of C2 were identified in the Fourier transform infrared emission spectra of hydrocarbon discharges. The B'1Σg+ v = 4 and the B1Δg v = 6, 7, and 8 vibrational levels involved in nine bands were studied for the first time. A direct global analysis with Dunham parameters was carried out satisfactorily for the B1Δg-A1Πu system except for a small perturbation in the B1Δg v = 6 level. The calculated rovibrational term energies up to B1Δg v = 12 showed that the level crossing between the B1Δg and d3Πg states is responsible for many of the prominent perturbations in the Swan system observed previously. Nineteen forbidden transitions of the B1Δg-a3Πu transition were identified and the off-diagonal spin-orbit interaction constant AdB between d3Πg and B1Δg was derived as 8.3(1) cm-1. For the B'1Σg+-A1Πu system, only individual band analyses for each vibrational level in the B'1Σg+ state could be done satisfactorily and Dunham parameters obtained from these effective parameters showed that the anharmonic vibrational constant ωexe is anomalously small (nearly zero). Inspection of the RKR (Rydberg-Klein-Rees) potential curves for the B'1Σg+ and X1Σg+ states revealed that an avoided crossing or nearly avoided crossing may occur around 30 000 cm-1, which is responsible for the anomalous molecular constants in these two states.

  1. Conceptual design and structural analysis of the spectroscopy of the atmosphere using far infrared emission (SAFIRE) instrument

    NASA Technical Reports Server (NTRS)

    Moses, Robert W.; Averill, Robert D.

    1992-01-01

    The conceptual design and structural analysis for the Spectroscopy of the Atmosphere using Far Infrared Emission (SAFIRE) Instrument are provided. SAFIRE, which is an international effort, is proposed for the Earth Observing Systems (EOS) program for atmospheric ozone studies. A concept was developed which meets mission requirements and is the product of numerous parametric studies and design/analysis iterations. Stiffness, thermal stability, and weight constraints led to a graphite/epoxy composite design for the optical bench and supporting struts. The structural configuration was determined by considering various mounting arrangements of the optical, cryo, and electronic components. Quasi-static, thermal, modal, and dynamic response analyses were performed, and the results are presented for the selected configuration.

  2. The chemical sensitivity of X-ray spectroscopy: high energy resolution XANES versus X-ray emission spectroscopy of substituted ferrocenes.

    PubMed

    Atkins, Andrew J; Bauer, Matthias; Jacob, Christoph R

    2013-06-07

    X-ray spectroscopy at the metal K-edge is an important tool for understanding catalytic processes and provides insight into the geometric and electronic structures of transition metal complexes. In particular, X-ray emission-based methods such as high-energy resolution fluorescence detection (HERFD), X-ray absorption near-edge spectroscopy (XANES) and valence-to-core X-ray emission spectroscopy (V2C-XES) hold the promise of providing increased chemical sensitivity compared to conventional X-ray absorption spectroscopy. Here, we explore the ability of HERFD-XANES and V2C-XES spectroscopy to distinguish substitutions beyond the directly coordinated atoms for the example of ferrocene and selected ferrocene derivatives. The experimental spectra are assigned and interpreted through the use of density functional theory (DFT) calculations. We find that while the pre-edge peaks in the HERFD-XANES spectra are affected by substituents at the cyclopentadienyl ring containing π-bonds [A. J. Atkins, Ch. R. Jacob and M. Bauer, Chem.-Eur. J., 2012, 18, 7021], the V2C-XES spectra are virtually unchanged. The pre-edge in HERFD-XANES probes the weak transition to unoccupied metal d-orbitals, while the V2C-XES spectra are determined by dipole-allowed transitions from occupied ligand orbitals to the 1s core hole. The latter turn out to be less sensitive to changes beyond the first coordination shell.

  3. Measurement of temperature profiles in flames by emission-absorption spectroscopy

    NASA Technical Reports Server (NTRS)

    Simmons, F. S.; Arnold, C. B.; Lindquist, G. H.

    1972-01-01

    An investigation was conducted to explore the use of infrared and ultraviolet emission-absorption spectroscopy for determination of temperature profiles in flames. Spectral radiances and absorptances were measured in the 2.7-micron H2O band and the 3064-A OH band in H2/O2 flames for several temperature profiles which were directly measured by a sodium line-reversal technique. The temperature profiles, determined by inversion of the infrared and ultraviolet spectra, showed an average disagreement with line-reversal measurements of 50 K for the infrared and 200 K for the ultraviolet at a temperature of 2600 K. The reasons for these discrepancies are discussed in some detail.

  4. Angle resolved photo-emission spectroscopy signature of the resonant excitonic state

    NASA Astrophysics Data System (ADS)

    Montiel, X.; Kloss, T.; Pépin, C.

    2016-09-01

    We calculate the angle resolved photo-emission spectroscopy (ARPES) signature of the resonant excitonic state (RES) that was proposed as the pseudo-gap state of cuprate superconductors (Kloss T. et al., arXiv:1510.03038 (2015)). This new state can be described as a set of excitonic (particle-hole) patches with an internal checkerboard modulation. Here, we modelize the RES as a charge order with 2\\textbf{p}F wave vectors, where 2\\textbf{p}F is the ordering vector connecting two opposite sides of the Fermi surface. We calculate the spectral weight and the density of states in the RES and we find that our model correctly reproduces the opening of the PG in Bi-2201.

  5. Temperature Effect on the Optical Emission Intensity in Laser Induced Breakdown Spectroscopy of Super Alloys

    NASA Astrophysics Data System (ADS)

    Darbani, S. M. R.; Ghezelbash, M.; Majd, A. E.; Soltanolkotabi, M.; Saghafifar, H.

    2014-12-01

    In this paper, the influence of heating and cooling samples on the optical emission spectra and plasma parameters of laser-induced breakdown spectroscopy for Titanium 64, Inconel 718 super alloys, and Aluminum 6061 alloy is investigated. Samples are uniformly heated up to approximately 200°C and cooled down to -78°C by an external heater and liquid nitrogen, respectively. Variations of plasma parameters like electron temperature and electron density with sample temperature are determined by using Boltzmann plot and Stark broadening methods, respectively. Heating the samples improves LIBS signal strength and broadens the width of the spectrum. On the other hand, cooling alloys causes fluctuations in the LIBS signal and decrease it to some extent, and some of the spectral peaks diminish. In addition, our results show that electron temperature and electron density depend on the sample temperature variations.

  6. Measurement of the stratospheric hydrogen peroxide concentration profile using far infrared thermal emission spectroscopy

    NASA Technical Reports Server (NTRS)

    Chance, K. V.; Johnson, D. G.; Traub, W. A.; Jucks, K. W.

    1991-01-01

    The first unequivocal measurement of hydrogen peroxide in the stratosphere have been made, a concentration profile obtained from a balloon platform using Fourier transform thermal emission spectroscopy in the far infrared. Measurements were made using the 112/cm R-Q5 branch of the rotational-torsional spectrum, with some confirmation from the 94/cm R-Q4 branch. The volume mixing ratio of H2O2 is 1.6 x 10 to the -10th at 38.4 km, decreasing to 0.6 x 10 to the -10th at 23.8 km, with uncertainties of about 16 percent. These measurements are compared to a recent stratospheric model calculation.

  7. Analysis of edge density fluctuation measured by trial KSTAR beam emission spectroscopy system

    SciTech Connect

    Nam, Y. U.; Zoletnik, S.; Lampert, M.; Kovacsik, A.

    2012-10-15

    A beam emission spectroscopy (BES) system based on direct imaging avalanche photodiode (APD) camera has been designed for Korea Superconducting Tokamak Advanced Research (KSTAR) and a trial system has been constructed and installed for evaluating feasibility of the design. The system contains two cameras, one is an APD camera for BES measurement and another is a fast visible camera for position calibration. Two pneumatically actuated mirrors were positioned at front and rear of lens optics. The front mirror can switch the measurement between edge and core region of plasma and the rear mirror can switch between the APD and the visible camera. All systems worked properly and the measured photon flux was reasonable as expected from the simulation. While the measurement data from the trial system were limited, it revealed some interesting characteristics of KSTAR plasma suggesting future research works with fully installed BES system. The analysis result and the development plan will be presented in this paper.

  8. Multielement analysis of geologic materials by inductively coupled plasma-atomic emission spectroscopy

    SciTech Connect

    Christensen, O.D.; Kroneman, R.L.; Capuano, R.M.

    1980-03-01

    Atomic emission spectroscopy using an inductively coupled plasma (ICP) source permits the rapid acquisition of multielement geochemical data from a wide variety of geologic materials. Rocks or other solid samples are taken into solution with a four acid digestion procedure and introduced directly into the plasma; fluid samples are acidified or analyzed directly. The entire process is computer-controlled, fully-automated, and requires less than five minutes per sample for quantitative determination of 37 elements. The procedures and instrumentation employed at the ESL for multielement ICP analysis of geologic materials are described and these are intended as a guide for evaluating analytic results reported from this laboratory. The quality of geochemical data can be characterized by precision, limits of quantitative determination, and accuracy. Precision values are a measure of the repeatability of analyses. In general, major element and analyses have precision of better than 5% and trace elements of better than 10% of the amount present. (MHR)

  9. Ballistic-electron-emission-spectroscopy detection of monolayer thickness fluctuations in a semiconductor heterostructure

    NASA Astrophysics Data System (ADS)

    Guthrie, D. K.; First, P. N.; Gaylord, T. K.; Glytsis, E. N.; Leibenguth, R. E.

    1999-07-01

    Ballistic-electron-emission spectroscopy (BEES) is used to measure fluctuations in the thickness of buried Ga0.8Al0.2As layers. The device under measurement is a half-electron-wavelength Fabry-Perot filter that has been designed to have two quasibound states. By performing BEES at several different spatial locations and by utilizing the relationship between the thicknesses of the device layers and the location (in energy) of the quasibound states, single-monolayer variations are detected in the thicknesses of both the GaAs quantum well and the surrounding Ga0.8Al0.2As barriers. The lateral resolution is shown to be better than 20 nm.

  10. Gas recognition using a neural network approach to plasma optical emission spectroscopy

    NASA Astrophysics Data System (ADS)

    Hyland, Mark; Mariotti, Davide; Dubitzky, Werner; McLaughlin, James A.; Maguire, Paul

    2000-10-01

    A system has been developed which enables the detection and recognition of various gases. Plasma emission spectroscopy has been used to record spectra from volatile species of acetone, vinegar, and coffee beans, along with air and nitrogen spectra. The spectra have been uniquely processed and fed into an artificial neural network program for training and recognition of unknown gases. The system as a whole can be grouped into the emerging and diverse area of artificial nose technology. The sy stem has shown to provide a solution to the recognition of simple gases and odours (air, nitrogen, acetone) and could also satisfactorily recognise more complex samples (vinegar and coffee beans). Recognition is performed in seconds; this being a positive aspect for many artificial nose applications.

  11. Three-dimensional modeling of beam emission spectroscopy measurements in fusion plasmas

    SciTech Connect

    Guszejnov, D.; Pokol, G. I.; Pusztai, I.; Refy, D.; Zoletnik, S.; Lampert, M.; Nam, Y. U.

    2012-11-15

    One of the main diagnostic tools for measuring electron density profiles and the characteristics of long wavelength turbulent wave structures in fusion plasmas is beam emission spectroscopy (BES). The increasing number of BES systems necessitated an accurate and comprehensive simulation of BES diagnostics, which in turn motivated the development of the Rate Equations for Neutral Alkali-beam TEchnique (RENATE) simulation code that is the topic of this paper. RENATE is a modular, fully three-dimensional code incorporating all key features of BES systems from the atomic physics to the observation, including an advanced modeling of the optics. Thus RENATE can be used both in the interpretation of measured signals and the development of new BES systems. The most important components of the code have been successfully benchmarked against other simulation codes. The primary results have been validated against experimental data from the KSTAR tokamak.

  12. Diagnostic performance of the beam emission spectroscopy system on the National Spherical Torus Experiment

    SciTech Connect

    Smith, D. R.; Fonck, R. J.; McKee, G. R.; Thompson, D. S.

    2012-10-15

    The beam emission spectroscopy system on the National Spherical Torus Experiment measures localized density fluctuations on the ion gyroscale. Optical sightlines provide core to edge radial coverage, and the sightlines are aligned to typical pitch angles to maximize cross-field spatial resolution. Sightline images are 2-3 cm, and point spread function calculations indicate image distortion from pitch angle misalignment and atomic state finite lifetimes is minor with a 15% increase in the image size. New generation photodetectors achieve photon noise limited measurements at frequencies up to 400 kHz with refrigerant cooling at -20 Degree-Sign C. Measurements near the pedestal show broadband turbulence up to 100 kHz, and poloidal correlation lengths are about 10 cm. Plasma turbulence signals can be 2-3 orders of magnitude above photon noise and amplifier thermal noise.

  13. Measurement of lanthanum and technetium in uranium fuels by inductively coupled plasma atomic emission spectroscopy.

    SciTech Connect

    Carney, K.; Crane, P.; Cummings, D.; Krsul, J.; McKnight, R.

    1999-06-10

    An important parameter in characterizing an irradiated nuclear fuel is determining the amount of uranium fissioned. By determining the amount of uranium fissioned in the fuel a burnup performance parameter can be calculated, and the amount of fission products left in the fuel can be predicted. The quantity of uranium fissioned can be calculated from the amount of lanthanum and technetium present in the fuel. Lanthanum and technetium were measured in irradiated fuel samples using an Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-AES) instrument and separation equipment located in a shielded glove-box. A discussion of the method, interferences, detection limits, quality control and a comparison to other work will be presented.

  14. Spatially Resolved HST Grism Spectroscopy of a Lensed Emission Line Galaxy at z ~ 1

    NASA Astrophysics Data System (ADS)

    Frye, Brenda L.; Hurley, Mairead; Bowen, David V.; Meurer, Gerhardt; Sharon, Keren; Straughn, Amber; Coe, Dan; Broadhurst, Tom; Guhathakurta, Puragra

    2012-07-01

    We take advantage of gravitational lensing amplification by A1689 (z = 0.187) to undertake the first space-based census of emission line galaxies (ELGs) in the field of a massive lensing cluster. Forty-three ELGs are identified to a flux of i 775 = 27.3 via slitless grism spectroscopy. One ELG (at z = 0.7895) is very bright owing to lensing magnification by a factor of ≈4.5. Several Balmer emission lines (ELs) detected from ground-based follow-up spectroscopy signal the onset of a major starburst for this low-mass galaxy (M * ≈ 2 × 109 M ⊙) with a high specific star formation rate (≈20 Gyr-1). From the blue ELs we measure a gas-phase oxygen abundance consistent with solar (12+log(O/H) = 8.8 ± 0.2). We break the continuous line-emitting region of this giant arc into seven ~1 kpc bins (intrinsic size) and measure a variety of metallicity-dependent line ratios. A weak trend of increasing metal fraction is seen toward the dynamical center of the galaxy. Interestingly, the metal line ratios in a region offset from the center by ~1 kpc have a placement on the blue H II region excitation diagram with f ([O III])/f (Hβ) and f ([Ne III])/f (Hβ) that can be fitted by an active galactic nucleus (AGN). This asymmetrical AGN-like behavior is interpreted as a product of shocks in the direction of the galaxy's extended tail, possibly instigated by a recent galaxy interaction. Based, in part, on data obtained with the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and NASA, and was made possible by the generous financial support of the W. M. Keck Foundation.

  15. Resonant x-ray emission spectroscopy of liquid water: novel instrumentation, high resolution, and the"map" approach

    SciTech Connect

    Weinhardt, L.; Fuchs, O.; Blum, M.; Bär, M.; Weigand, M.; Denlinger, J.D.; Zubavichus, Y.; Zharnikov, M.; Grunze, M.; Heske, C.; Umbach, E.

    2008-06-17

    Techniques to study the electronic structure of liquids are rare. Most recently, resonant x-ray emission spectroscopy (XES) has been shown to be an extremely versatile spectroscopy to study both occupied and unoccupied electronic states for liquids in thermodynamic equilibrium. However, XES requires high-brilliance soft x-ray synchrotron radiation and poses significant technical challenges to maintain a liquid sample in an ultra-high vacuum environment. Our group has therefore developed and constructed a novel experimental setup for the study of liquids, with the long-term goal of investigating the electronic structure of biological systems in aqueous environments. We have developed a flow-through liquid cell in which the liquid is separated from vacuum by a thin Si3N4 or SiC window and which allows a precise control of temperature. This approach has significant advantages compared to static liquids cells used in the past. Furthermore, we have designed a dedicated high-transmission, high-resolution soft x-ray spectrometer. The high transmission makes it possible to measure complete resonant XES"maps" in less than an hour, giving unprecedented detailed insight into the electronic structure of the investigated sample. Using this new equipment we have investigated the electronic structure of liquid water. Furthermore, our XES spectra and maps give information about ultra-fast dissociation on the timescale of the O 1s core hole lifetime, which is strongly affected by the initial state hydrogen bonding configuration.

  16. Electronic Structure of the ID Conductor K0.3MoO3 studied using resonant inelastic x-ray scattering and soft x-ray emission spectroscopy

    SciTech Connect

    Learmonth, T.; Glans, P.-A.; McGuinness, C.; Plucinski, L.; Zhang, Y.; Guo, J.-H.; Greenblatt, M.; Smith, K.E.

    2008-09-24

    The electronic structure of the quasi-one dimensional conductor K{sub 0.3}MoO{sub 3} has been measured using high resolution resonant inelastic x-ray scattering and x-ray absorption spectroscopy. The data is compared to that from the related two dimensional insulator {alpha}-MoO{sub 3}. Scattering features are observed from both oxides that are explained in terms of the band momentum selectivity of the scattering process, allowing a comparison of the scattering data to recent band structure calculations.

  17. Electronic structure of multiferroic BiFeO3 by resonant soft x-ray emission spectroscopy

    NASA Astrophysics Data System (ADS)

    Higuchi, Tohru; Liu, Yi-Sheng; Yao, Peng; Glans, Per-Anders; Guo, Jinghua; Chang, Chinglin; Wu, Ziyu; Sakamoto, Wataru; Itoh, Naoyuki; Shimura, Tetsuo; Yogo, Toshinobu; Hattori, Takeshi

    2008-08-01

    The electronic structure of multiferroic BiFeO3 has been studied using soft x-ray emission spectroscopy. The fluorescence spectra exhibit that the valence band is mainly composed of O2p state hybridized with Fe3d state. The band gap corresponding to the energy separation between the top of the O2p valence band and the bottom of the Fe3d conduction band is 1.3 eV. The soft x-ray Raman scattering reflects the features due to the charge-transfer transition from O2p valence band to Fe3d conduction band. These findings are similar to the result of electronic structure calculation by density-functional theory within the local spin-density approximation that included the effect of Coulomb repulsion between localized d states.

  18. Electronic structure of multiferroic BiFeO3 by resonant soft-x-ray emission spectroscopy

    SciTech Connect

    Higuchi, Tohru; Higuchi, T.; Liu, Y.-S.; Yao, P.; Glans, P.-A.; Guo, Jinghua; Chang, C.; Wu, Z.; Sakamoto, W.; Itoh, N.; Shimura, T.; Yogo, T.; Hattori, T.

    2008-07-11

    The electronic structure of multiferroic BiFeO{sub 3} has been studied using soft-X-ray emission spectroscopy. The fluorescence spectra exhibit that the valence band is mainly composed of O 2p state hybridized with Fe 3d state. The band gap corresponding to the energy separation between the top of the O 2p valence band and the bottom of the Fe 3d conduction band is 1.3 eV. The soft-X-ray Raman scattering reflects the features due to charge transfer transition from O 2p valence band to Fe 3d conduction band. These findings are similar to the result of electronic structure calculation by density functional theory within the local spin-density approximation that included the effect of Coulomb repulsion between localized d states.

  19. Combined hydrogen and lithium beam emission spectroscopy observation system for Korea Superconducting Tokamak Advanced Research

    SciTech Connect

    Lampert, M.; Anda, G.; Réfy, D.; Zoletnik, S.; Czopf, A.; Erdei, G.; Guszejnov, D.; Kovácsik, Á.; Pokol, G. I.; Nam, Y. U.

    2015-07-15

    A novel beam emission spectroscopy observation system was designed, built, and installed onto the Korea Superconducting Tokamak Advanced Research tokamak. The system is designed in a way to be capable of measuring beam emission either from a heating deuterium or from a diagnostic lithium beam. The two beams have somewhat complementary capabilities: edge density profile and turbulence measurement with the lithium beam and two dimensional turbulence measurement with the heating beam. Two detectors can be used in parallel: a CMOS camera provides overview of the scene and lithium beam light intensity distribution at maximum few hundred Hz frame rate, while a 4 × 16 pixel avalanche photo-diode (APD) camera gives 500 kHz bandwidth data from a 4 cm × 16 cm region. The optics use direct imaging through lenses and mirrors from the observation window to the detectors, thus avoid the use of costly and inflexible fiber guides. Remotely controlled mechanisms allow adjustment of the APD camera’s measurement location on a shot-to-shot basis, while temperature stabilized filter holders provide selection of either the Doppler shifted deuterium alpha or lithium resonance line. The capabilities of the system are illustrated by measurements of basic plasma turbulence properties.

  20. Initial density fluctuation measurements from the NSTX Beam Emission Spectroscopy diagnostic system*

    NASA Astrophysics Data System (ADS)

    Smith, D. R.; Fonck, R. J.; McKee, G. R.; Schoenbeck, N. L.; Thompson, D.; Uzun-Kaymak, I. U.; Stratton, B. C.

    2010-11-01

    Density fluctuation measurements on the ion gyroscale have been obtained on NSTX with a newly commissioned beam emission spectroscopy (BES) diagnostic system. The BES system measures red-shifted Dα emission near 660 nm from deuterium neutral beams with high throughput optics and high efficiency detectors. The system presently employs 16 detection channels arranged in radial and poloidal arrays, and an expansion to 32 channels is planned. Radial arrays can measure fluctuations from r/a 0.1 to beyond the last closed flux surface and resolve fluctuations with kρi<=1.5. Initial BES measurements reveal broadband turbulence and coherent modes below 300 kHz for r/a>=0.4. The broadband turbulence appears in high gradient regions and increases at H-L transitions. The frequency characteristics of the coherent modes correlate with Alfvén/energetic particle modes in Mirnov probe measurements, but some coherent modes appear in BES measurements only. *Supported by the U.S. Department of Energy under Contract Nos. DE-FG02-89ER53296, DE-AC02-09CH11466 and DE-SC0001288.

  1. LZIFU: an emission-line fitting toolkit for integral field spectroscopy data

    NASA Astrophysics Data System (ADS)

    Ho, I.-Ting; Medling, Anne M.; Groves, Brent; Rich, Jeffrey A.; Rupke, David S. N.; Hampton, Elise; Kewley, Lisa J.; Bland-Hawthorn, Joss; Croom, Scott M.; Richards, Samuel; Schaefer, Adam L.; Sharp, Rob; Sweet, Sarah M.

    2016-09-01

    We present lzifu (LaZy-IFU), an idl toolkit for fitting multiple emission lines simultaneously in integral field spectroscopy (IFS) data. lzifu is useful for the investigation of the dynamical, physical and chemical properties of gas in galaxies. lzifu has already been applied to many world-class IFS instruments and large IFS surveys, including the Wide Field Spectrograph, the new Multi Unit Spectroscopic Explorer (MUSE), the Calar Alto Legacy Integral Field Area (CALIFA) survey, the Sydney-Australian-astronomical-observatory Multi-object Integral-field spectrograph (SAMI) Galaxy Survey. Here we describe in detail the structure of the toolkit, and how the line fluxes and flux uncertainties are determined, including the possibility of having multiple distinct kinematic components. We quantify the performance of lzifu, demonstrating its accuracy and robustness. We also show examples of applying lzifu to CALIFA and SAMI data to construct emission line and kinematic maps, and investigate complex, skewed line profiles presented in IFS data. The code is made available to the astronomy community through github. lzifu will be further developed over time to other IFS instruments, and to provide even more accurate line and uncertainty estimates.

  2. Anisotropic emission in quantum-beat spectroscopy of helium excited states

    NASA Astrophysics Data System (ADS)

    Lucchini, M.; Ludwig, A.; Zimmermann, T.; Kasmi, L.; Herrmann, J.; Scrinzi, A.; Landsman, A. S.; Gallmann, L.; Keller, U.

    2015-06-01

    We present quantum-beat spectroscopy of excited states of helium atoms populated selectively with high-order-harmonic emission below the atomic ionization potential by means of low-pass filtering of the pump radiation. The created electron wave packet is ionized by few-cycle infrared (IR) pulses leading to characteristic peaks in the photoelectron yield, which beat with a frequency proportional to the energy gap between the states involved in the two-color photoionization process. Minimizing the direct ionization by the extreme ultraviolet (XUV) radiation, we can follow the evolution of the electron wave packet also in the region of temporal pump-probe overlap. A detailed time-frequency analysis of the quantum beats and direct comparison with the solution of the time-dependent Schrödinger equation reveal the existence of quantum beats characterized by a final state of mixed parity. Finally, we show that by varying the carrier-envelope offset phase of the probe pulse, one can optically control the preferred direction of photoelectron emission and the contrast of such beats.

  3. Combined hydrogen and lithium beam emission spectroscopy observation system for Korea Superconducting Tokamak Advanced Research.

    PubMed

    Lampert, M; Anda, G; Czopf, A; Erdei, G; Guszejnov, D; Kovácsik, Á; Pokol, G I; Réfy, D; Nam, Y U; Zoletnik, S

    2015-07-01

    A novel beam emission spectroscopy observation system was designed, built, and installed onto the Korea Superconducting Tokamak Advanced Research tokamak. The system is designed in a way to be capable of measuring beam emission either from a heating deuterium or from a diagnostic lithium beam. The two beams have somewhat complementary capabilities: edge density profile and turbulence measurement with the lithium beam and two dimensional turbulence measurement with the heating beam. Two detectors can be used in parallel: a CMOS camera provides overview of the scene and lithium beam light intensity distribution at maximum few hundred Hz frame rate, while a 4 × 16 pixel avalanche photo-diode (APD) camera gives 500 kHz bandwidth data from a 4 cm × 16 cm region. The optics use direct imaging through lenses and mirrors from the observation window to the detectors, thus avoid the use of costly and inflexible fiber guides. Remotely controlled mechanisms allow adjustment of the APD camera's measurement location on a shot-to-shot basis, while temperature stabilized filter holders provide selection of either the Doppler shifted deuterium alpha or lithium resonance line. The capabilities of the system are illustrated by measurements of basic plasma turbulence properties.

  4. Combined hydrogen and lithium beam emission spectroscopy observation system for Korea Superconducting Tokamak Advanced Research

    NASA Astrophysics Data System (ADS)

    Lampert, M.; Anda, G.; Czopf, A.; Erdei, G.; Guszejnov, D.; Kovácsik, Á.; Pokol, G. I.; Réfy, D.; Nam, Y. U.; Zoletnik, S.

    2015-07-01

    A novel beam emission spectroscopy observation system was designed, built, and installed onto the Korea Superconducting Tokamak Advanced Research tokamak. The system is designed in a way to be capable of measuring beam emission either from a heating deuterium or from a diagnostic lithium beam. The two beams have somewhat complementary capabilities: edge density profile and turbulence measurement with the lithium beam and two dimensional turbulence measurement with the heating beam. Two detectors can be used in parallel: a CMOS camera provides overview of the scene and lithium beam light intensity distribution at maximum few hundred Hz frame rate, while a 4 × 16 pixel avalanche photo-diode (APD) camera gives 500 kHz bandwidth data from a 4 cm × 16 cm region. The optics use direct imaging through lenses and mirrors from the observation window to the detectors, thus avoid the use of costly and inflexible fiber guides. Remotely controlled mechanisms allow adjustment of the APD camera's measurement location on a shot-to-shot basis, while temperature stabilized filter holders provide selection of either the Doppler shifted deuterium alpha or lithium resonance line. The capabilities of the system are illustrated by measurements of basic plasma turbulence properties.

  5. Results of the air emission research study

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Air quality was monitored in beef mono-slope barns. The objectives of the study were 1) to gather baseline data for the levels of gas emissions and particulate matter from beef mono-slope facilities, 2) evaluate the effect of two different manure handling systems on air quality, and 3) provide infor...

  6. Far-red to near infrared emission and scattering spectroscopy for biomedical applications

    NASA Astrophysics Data System (ADS)

    Zhang, Gang

    2001-06-01

    The thesis investigates the far-red and near infrared (NIR) spectral region from biomedical tissue samples for monitoring the state of tissues. The NIR emission wing intensity is weak in comparison to the emission in the visible spectral region. The wing emission from biomedical samples has revealed meaningful information about the state of the tissues. A model is presented to explain the shape of the spectral wing based on a continuum of energy levels. The wing can be used to classify different kinds of tissues; especially it can be used to differentiate cancer part from normal human breast tissues. The research work of the far-red emission from thermal damaged tissue samples shows that the emission intensity in this spectral region is proportional to the extent of the thermal damage of the tissue. Near infrared spectral absorption method is used to investigate blood hemodynamics (perfusion and oxygenation) in brain during sleep-wake transition. The result of the research demonstrates that the continuous wave (CW) type near infrared spectroscopy (NIRS) device can be used to investigate brain blood perfusion and oxygenation with a similar precision with frequency domain (FD) type device. The human subject sleep and wake transition, has been monitored by CW type NIRS instrument with traditional electroencephalograph (EEG) method. Parallel change in oxy-Hb and deoxy-Hb is a discrete event that occurs in the transition from both sleep to wakefulness and wakefulness to sleep. These hemodynamic switches are generally about few seconds delayed from the human decided transition point between sleep and wake on the polygraph EEG recording paper. The combination of NIRS and EEG methods monitor the brain activity, gives more information about the brain activity. The sleep apnea investigation was associated with recurrent apneas, insufficient nasal continuous positive airway pressure (CPAP) and the different response of the peripheral and central compartments to breathing

  7. Study of clusters using negative ion photodetachment spectroscopy

    SciTech Connect

    Zhao, Yuexing

    1995-12-01

    The weak van der Waals interaction between an open-shell halogen atom and a closed-shell atom or molecule has been investigated using zero electron kinetic energy (ZEKE) spectroscopy. This technique is also applied to study the low-lying electronic states in GaAs and GaAs-. In addition, the spectroscopy and electron detachment dynamics of several small carbon cluster anions are studied using resonant multiphoton detachment spectroscopy.

  8. Study of Infrared Emission Spectroscopy for the B1Δg-A1Πu and B'1Σg+-A1Πu Systems of C2

    NASA Astrophysics Data System (ADS)

    Tang, Jian; Chen, Wang; Kawaguchi, Kentarou; Bernath, Peter F.

    2016-06-01

    Recently, we carried out the perturbation analysis of C_2 spectra and identified forbidden singlet-triplet intersystem transitions, which aroused further interest in other C_2 spectra for the many low-lying electronic states of this fundamental molecule. In 1988, the B1Δg-A1Πu and B'1Σg+-A1Πu band systems were discovered by Douay et al., who observed eight bands of the B1Δg-A1Πu system with v up to 5 for the B1Δg state and six bands of the B'1Σg+-A1Πu system with v up to 3 for the B'1Σg+ state in the Fourier transform infrared emission spectra of hydrocarbon discharges. In the work presented here, we identified twenty-four bands of the two systems, among which the B'1Σg+ v = 4 and the B1Δg v = 6, 7 and 8 vibrational levels involved in nine bands were studied for the first time. A direct global analysis with Dunham parameters was carried out satisfactorily for the B1Δg-A1Πu system except for a small perturbation in the B1Δg v = 6 level. The calculated rovibrational term energies up to B1Δg v = 12 showed that the level crossing between the B1Δg and d3Πg states is responsible for many of the prominent perturbations in the Swan system observed previously. Nineteen lines of the B1Δg-a3Πu forbidden transitions were identified and the off-diagonal spin-orbit interaction constant AdB between d3Πg and B1Δg was derived as 8.3(1) wn. For the B'1Σg+-A1Πu system, only individual band analyses for each vibrational level in the B'1Σg+ state could be done satisfactorily and Dunham parameters obtained from these effective parameters showed that the anharmonic vibrational constant ω_e x_e is anomalously small (nearly zero). Inspection of the RKR potential curves for the B'1Σg+ and X1Σg+ states revealed that an avoided crossing may occur around 30000 wn, which is responsible for the anomalous molecular constants in these two states. W. Chen, K. Kawaguchi, P. F. Bernath, and J. Tang, J. Chem. Phys., 141, 064317 (2015) M. Douay, R. Nietmann and P. F. Bernath

  9. Feasibility study for detecting copper contaminants in transformer insulation using laser-induced breakdown spectroscopy

    NASA Astrophysics Data System (ADS)

    Aparna, N.; Vasa, Nilesh J.; Sarathi, R.; Rajan, J. Sundara

    2014-10-01

    In recent times, copper sulphide (Cu2S) diffusion in the transformer insulation is a major problem reducing the life of transformers. It is therefore essential to identify a simple methodology to understand the diffusion of Cu2S into the solid insulation [oil impregnated pressboard (OIP)]. In the present work, laser-induced breakdown spectroscopy (LIBS) was adopted to study the diffusion of Cu2S into the pressboard insulation and to determine the depth of diffusion. The diffusion of Cu2S in pressboard was confirmed by electrical discharge studies. In general, flashover voltage and increase in ageing duration of pressboard insulation/Cu concentration had inverse relationship. The characteristic emission lines were also studied through optical emission spectroscopy. Based on LIBS studies with Cu powder dispersed pressboard samples, Cu I emission lines were found to be resolvable up to a lowest concentration of 5 μg/cm2. The LIBS intensity ratio of Cu I-Ca II emission lines were found to increase with increase in the ageing duration of the OIP sample. LIBS studies with OIP samples showed an increase in the optical emission lifetime. LIBS results were in agreement with the electrical discharge studies.

  10. Raman spectroscopy of gliomas: an exploratory study

    NASA Astrophysics Data System (ADS)

    Shenoy, Mahesh; Hole, Arti R.; Shridhar, E.; Moiyadi, Aliasgar V.; Krishna, C. Murali

    2014-03-01

    Gliomas are extremely infiltrative type of brain cancers, the borders of which are difficult to locate. Gliomas largely consist of tumors of astrocytic or oligodendroglial lineage. Usually stereotactic surgery is performed to obtain tumor tissue sample. Complete excision of these tumors with preservation of uninvolved normal areas is important during brain tumor surgeries. The present study was undertaken to explore feasibility of classifying abnormal and normal glioma tissues with Raman spectroscopy (RS). RS is a nondestructive vibrational spectroscopic technique, which provides information about molecular composition, molecular structures and molecular interactions in tissue. Postoperated 33 (20-abnormal and 13-normal) gliomas tissue samples of different grades were collected under clinical supervision. Five micron section from tissue sample was used for confirmatory histopathological diagnosis while the remaining tissue was placed on CaF2 window and spectra were acquired using a fiberoptic-probe-coupled HE-785 Raman-spectrometer. Spectral acquisition parameters were laser power-80mW, integration-20s and averaged over 3 accumulations. Spectra were pre-processed and subjected to unsupervised Principal-Component Analysis (PCA) to identify trends of classification. Supervised PC-LDA (Principal-Component-Linear-Discriminant Analysis) was used to develop standard-models using spectra of 12 normal and abnormal specimens each. Leave-one-out crossvalidation yielded classification-efficiency of 90% and 80% for normal and abnormal conditions, respectively. Evaluation with an independent-test data-set comprising of 135 spectra of 9 samples provided sensitivity of 100% and specificity of 70%. Findings of this preliminary study may pave way for objective tumor margin assessment during brain surgery.

  11. Development of Advanced Electrochemical Emission Spectroscopy for Monitoring Corrosion in Simulated DOE Liquid Waste

    SciTech Connect

    Digby D. Macdonald; Brian M. Marx; Sejin Ahn; Julio de Ruiz; Balaji Soundararaja; Morgan Smith; and Wendy Coulson

    2008-01-15

    Various forms of general and localized corrosion represent principal threats to the integrity of DOE liquid waste storage tanks. These tanks, which are of a single wall or double wall design, depending upon their age, are fabricated from welded carbon steel and contain a complex waste-form comprised of NaOH and NaNO{sub 3}, along with trace amounts of phosphate, sulfate, carbonate, and chloride. Because waste leakage can have a profound environmental impact, considerable interest exists in predicting the accumulation of corrosion damage, so as to more effectively schedule maintenance and repair. The different tasks that are being carried out under the current program are as follows: (1) Theoretical and experimental assessment of general corrosion of iron/steel in borate buffer solutions by using electrochemical impedance spectroscopy (EIS), ellipsometry and XPS techniques; (2) Development of a damage function analysis (DFA) which would help in predicting the accumulation of damage due to pitting corrosion in an environment prototypical of DOE liquid waste systems; (3) Experimental measurement of crack growth rate, acoustic emission signals and coupling currents for fracture in carbon and low alloy steels as functions of mechanical (stress intensity), chemical (conductivity), electrochemical (corrosion potential, ECP), and microstructural (grain size, precipitate size, etc) variables in a systematic manner, with particular attention being focused on the structure of the noise in the current and its correlation with the acoustic emissions; (4) Development of fracture mechanisms for carbon and low alloy steels that are consistent with the crack growth rate, coupling current data and acoustic emissions; (5) Inserting advanced crack growth rate models for SCC into existing deterministic codes for predicting the evolution of corrosion damage in DOE liquid waste storage tanks; (6) Computer simulation of the anodic and cathodic activity on the surface of the steel samples

  12. MEASURING ORGANIC MOLECULAR EMISSION IN DISKS WITH LOW-RESOLUTION SPITZER SPECTROSCOPY

    SciTech Connect

    Teske, Johanna K.; Najita, Joan R.; Carr, John S.; Pascucci, Ilaria; Apai, Daniel; Henning, Thomas E-mail: najita@noao.edu E-mail: pascucci@stsci.edu E-mail: henning@mpia.de

    2011-06-10

    We explore the extent to which Spitzer Infrared Spectrograph (IRS) spectra taken at low spectral resolution can be used in quantitative studies of organic molecular emission from disks surrounding low-mass young stars. We use Spitzer IRS spectra taken in both the high- and low-resolution modules for the same sources to investigate whether it is possible to define line indices that can measure trends in the strength of the molecular features in low-resolution data. We find that trends in the HCN emission strength seen in the high-resolution data can be recovered in low-resolution data. In examining the factors that influence the HCN emission strength, we find that the low-resolution HCN flux is modestly correlated with stellar accretion rate and X-ray luminosity. Correlations of this kind are perhaps expected based on recent observational and theoretical studies of inner disk atmospheres. Our results demonstrate the potential of using the large number of low-resolution disk spectra that reside in the Spitzer archive to study the factors that influence the strength of molecular emission from disks. Such studies would complement results for the much smaller number of circumstellar disks that have been observed at high resolution with IRS.

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

    NASA Astrophysics Data System (ADS)

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

    2016-10-01

    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(1s5) 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(1s3) 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.

  14. Alpha Coincidence Spectroscopy studied with GEANT4

    SciTech Connect

    Dion, Michael P.; Miller, Brian W.; Tatishvili, Gocha; Warren, Glen A.

    2013-11-02

    Abstract The high-energy side of peaks in alpha spectra, e.g. 241Am, as measured with a silicon detector has structure caused mainly by alpha-conversion electron and to some extent alphagamma coincidences. We compare GEANT4 simulation results to 241Am alpha spectroscopy measurements with a passivated implanted planar silicon detector. A large discrepancy between the measurements and simulations suggest that the GEANT4 photon evaporation database for 237Np (daughter of 241Am decay) does not accurately describe the conversion electron spectrum and therefore was found to have large discrepancies with experimental measurements. We describe how to improve the agreement between GEANT4 and alpha spectroscopy for actinides of interest by including experimental measurements of conversion electron spectroscopy into the photon evaporation database.

  15. Infrared Heterodyne Spectroscopy and its Unique Application to Planetary Studies

    NASA Technical Reports Server (NTRS)

    Kostiuk, Theodore

    2009-01-01

    Since the early 1970's the infrared heterodyne technique has evolved into a powerful tool for the study of molecular constituents, temperatures, and dynamics in planetary atmospheres. Its extremely high spectral resolution (Lambda/(Delta)Lambda/>10(exp 6)) and highly accurate frequency measurement (to 1 part in 10(exp 8)) enabled the detection of nonthermal/natural lasing phenomena on Mars and Venus; direct measurements of winds on Venus, Mars, and Titan; study of mid-infrared aurorae on Jupiter; direct measurement of species abundances on Mars (ozone, isotopic CO2), hydrocarbons on Jupiter, Saturn., Neptune, and Titan, and stratospheric composition in the Earth's stratosphere (O3, CIO, N2O, CO2 ....). Fully resolved emission and absorption line shapes measured by this method enabled the unambiguous retrieval of molecular abundances and local temperatures and thermal structure in regions not probed by other techniques. The mesosphere of Mars and thermosphere of Venus are uniquely probed by infrared heterodyne spectroscopy. Results of these studies tested and constrained photochemical and dynamical theoretical models describing the phenomena measured. The infrared heterodyne technique will be described. Highlights in its evolution to today's instrumentation and resultant discoveries will be presented, including work at Goddard Space Flight Center and the University of Koln. Resultant work will include studies supporting NASA and ESA space missions and collaborations between instrumental and theoretical groups.

  16. X-ray emission spectroscopy applied to glycine adsorbed on Cu(110): An atom and symmetry projected view

    SciTech Connect

    Hasselstroem, J.; Karis, O.; Weinelt, M.

    1997-04-01

    When a molecule is adsorbed on a metal surface by chemical bonding new electronic states are formed. For noble and transition metals these adsorption-induced states overlap with the much more intense metal d-valence band, making them difficult to probe by for instance direct photoemission. However, it has recently been shown that X-ray emission spectroscopy (XES) can be applied to adsorbate systems. Since the intermediate state involves a core hole, this technique has the power to project out the partial density of states around each atomic site. Both the excitation and deexcitation processes are in general governed by the dipole selection rules. For oriented system, it is hence possible to obtain a complete separation into 2p{sub x}, 2p{sub y} and 2p{sub z} contributions using angular resolved measurements. The authors have applied XES together with other core level spectroscopies to glycine adsorption on Cu(110). Glycine (NH{sub 2}CH{sub 2}COOH) is the smallest amino acid and very suitable to study by core level spectroscopy since it has several functional groups, all well separated in energy by chemical shifts. Its properties are futhermore of biological interest. In summary, the authors have shown that it is possible to apply XES to more complicated molecular adsorbates. The assignment of different electronic states is however not as straight forward as for simple diatomic molecules. For a complete understanding of the redistribution and formation of new electronic states associated with the surface chemical bond, experimental data must be compared to theoretical calculations.

  17. Boronyl Mimics Gold: a Photoelectron Spectroscopy Study

    NASA Astrophysics Data System (ADS)

    Jian, Tian; Lopez, Gary; Wang, Lai-Sheng

    2015-06-01

    Previous studies have found that gold atom and boronyl bear similarities in bonding in many gas phase clusters. B10(BO), B12(BO), B3(BO)n (n=1, 2) were found to possess similar bonding and structures to B10Au, B12Au, B3Aun (n=1, 2), respectively. During the recent photoelectron spectroscopy experiments, the spectra of BiBO- and BiAu- clusters are found to exhibit similar patterns, hinting that they possess similar geometric structures. While BiAu- is a linear molecule, BiBO- is also linear. The similarity in bonding between BiBO- and BiAu- is owing to the fact that Au and BO are monovalent σ ligands. The electron affinities are measured to be 1.79±0.04eV for BiBO- and 1.36±0.02eV for BiAu-. The current results provide new examples for the BO/Au isolobal analogy and enrich the chemistry of boronyl and gold. H.-J. Zhai, C.-Q. Miao, S.-D. Li, L.-S. Wang, J. Phys. Chem. A 2010, 114, 12155-1216 Q. Chen, H. Bai, H.-J. Zhai, S.-D. Li, L.-S. Wang, J. Chem. Phys. 2013, 139, 044308 H. Bai, H.-J. Zhai, S.-D. Li, L.-S. Wang, Phys. Chem. Chem. Phys., 2013, 15, 9646-9653 H.-J. Zhai, Q. Chen, H. Bai, S.-D. Li, L.-S. Wang, Acc. Chem. Res. 2014, 47, 2435-2445

  18. First hydrogen operation of NIO1: Characterization of the source plasma by means of an optical emission spectroscopy diagnostic

    SciTech Connect

    Barbisan, M. Baltador, C.; Zaniol, B.; Pasqualotto, R.; Serianni, G.; Cavenago, M.; Fantz, U.; Wünderlich, D.; Vialetto, L.

    2016-02-15

    NIO1 (Negative Ion Optimization 1) is a compact and flexible radio frequency H{sup −} ion source, developed by Consorzio RFX and INFN-LNL. The aim of the experimentation on NIO1 is the optimization of both the production of negative ions and their extraction and beam optics. In the initial phase of its commissioning, NIO1 was operated with nitrogen, but now the source is regularly operated also with hydrogen. To evaluate the source performances, an optical emission spectroscopy diagnostic was installed. The system includes a low resolution spectrometer in the spectral range of 300-850 nm and a high resolution (50 pm) one, to study, respectively, the atomic and the molecular emissions in the visible range. The spectroscopic data have been interpreted also by means of a collisional-radiative model developed at IPP Garching. Besides the diagnostic hardware and the data analysis methods, the paper presents the first plasma measurements across a transition to the full H mode, in a hydrogen discharge. The characteristic signatures of this transition in the plasma parameters are described, in particular, the sudden increase of the light emitted from the plasma above a certain power threshold.

  19. Characterization of direct current He-N{sub 2} mixture plasma using optical emission spectroscopy and mass spectrometry

    SciTech Connect

    Flores, O.; Castillo, F.; Martinez, H.; Villa, M.; Reyes, P. G.; Villalobos, S.

    2014-05-15

    This study analyses the glow discharge of He and N{sub 2} mixture at the pressure of 2.0 Torr, power of 10 W, and flow rate of 16.5 l/min, by using optical emission spectroscopy and mass spectrometry. The emission bands were measured in the wavelength range of 200–1100 nm. The principal species observed were N{sub 2}{sup +} (B{sup 2}Σ{sup +}{sub u}→X{sup 2}Σ{sup +}{sub g}), N{sub 2} (C{sup 3}Π{sub u}→B{sup 3}Π{sub g}), and He, which are in good agreement with the results of mass spectrometry. Besides, the electron temperature and ion density were determined by using a double Langmuir probe. Results indicate that the electron temperature is in the range of 1.55–2.93 eV, and the electron concentration is of the order of 10{sup 10} cm{sup −3}. The experimental results of electron temperature and ion density for pure N{sub 2} and pure He are in good agreement with the values reported in the literature.

  20. 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.

    PubMed

    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.

  1. Characterisation of high current density resonant tunneling diodes for THz emission using photoluminescence spectroscopy

    NASA Astrophysics Data System (ADS)

    Jacobs, Kristof J. P.; Baba, Razvan; Stevens, Benjamin J.; Mukai, Toshikazu; Ohnishi, Dai; Hogg, Richard A.

    2016-03-01

    Resonant tunneling diodes (RTDs) provide high speed current oscillation which is applicable to THz generation when coupled to a suitably designed antenna. For this purpose, the InGaAs/AlAs/InP materials have been used, as this system offers high electron mobility, suitable band-offsets, and low resistance contacts. However for high current density operation (~MA/cm2) the epitaxial structure is challenging to characterize using conventional techniques as it consists of a single, very thin AlAs/InGaAs quantum well (QW). Here, we present a detailed low temperature photoluminescence spectroscopic study of high current density RTDs that allow the non-destructive mapping of a range of critical parameters for the device. We show how the doping level of the emitter/collector and contact layers in the RTD structure can be measured using the Moss-Burstein effect. For the full device structure, we show how emission from the QW may be identified, and detail how the emission changes with differing indium composition and well widths. We show that by studying nominally identical, un-doped structures, a type-II QW emission is observed, and explain the origin of the type-I emission in doped devices. This observation opens the way for a new characterization scheme where a "dummy" RTD active element is incorporated below the real RTD structure. This structure allows significantly greater control in the epitaxial process.

  2. Atom-specific look at the surface chemical bond using x-ray emission spectroscopy

    SciTech Connect

    Nilsson, A.; Wassdahl, N.; Weinelt, M.

    1997-04-01

    CO and N{sub 2} adsorbed on the late transition metals have become prototype systems regarding the general understanding of molecular adsorption. It is in general assumed that the bonding of molecules to transition metals can be explained in terms of the interaction of the frontier HOMO and LUMO molecular orbitals with the d-orbitals. In such a picture the other molecular orbitals should remain essentially the same as in the free molecule. For the adsorption of the isoelectronic molecules CO and N{sub 2} this has led to the so called Blyholder model i.e., a synergetic {sigma} (HOMO) donor and {pi} (LUMO) backdonation bond. The authors results at the ALS show that such a picture is oversimplified. The direct observation and identification of the states related to the surface chemical bond is an experimental challenge. For noble and transition metal surfaces, the adsorption induced states overlap with the metal d valence band. Their signature is therefore often obscured by bulk substrate states. This complication has made it difficult for techniques such as photoemission and inverse photoemission to provide reliable information on the energy of chemisorption induced states and has left questions unanswered regarding the validity of the frontier orbitals concept. Here the authors show how x-ray emission spectroscopy (XES), in spite of its inherent bulk sensitivity, can be used to investigate adsorbed molecules. Due to the localization of the core-excited intermediate state, XE spectroscopy allows an atomic specific separation of the valence electronic states. Thus the molecular contributions to the surface measurements make it possible to determine the symmetry of the molecular states, i.e., the separation of {pi} and {sigma} type states. In all the authors can obtain an atomic view of the electronic states involved in the formation of the chemical bond to the surface.

  3. Quantifying the relative contribution of natural gas fugitive emissions to total methane emissions in Colorado, Utah, and Texas using mobile isotopic methane analysis based on Cavity Ringdown Spectroscopy

    NASA Astrophysics Data System (ADS)

    Rella, Chris; Winkler, Renato; Sweeney, Colm; Karion, Anna; Petron, Gabrielle; Crosson, Eric

    2014-05-01

    Fugitive emissions of methane into the atmosphere are a major concern facing the natural gas production industry. Because methane is more energy-rich than coal per kg of carbon dioxide emitted into the atmosphere, it represents an attractive alternative to coal for electricity generation, provided that the fugitive emissions of methane are kept under control. A key step in assessing these emissions in a given region is partitioning the observed methane emissions between natural gas fugitive emissions and other sources of methane, such as from landfills or agricultural activities. One effective method for assessing the contribution of these different sources is stable isotope analysis, using the isotopic carbon signature to distinguish between natural gas and landfills or ruminants. We present measurements of methane using a mobile spectroscopic stable isotope analyzer based on cavity ringdown spectroscopy, in three intense natural gas producing regions of the United States: the Denver-Julesburg basin in Colorado, the Uintah basin in Utah, and the Barnett Shale in Texas. Performance of the CRDS isotope analyzer is presented, including precision, calibration, stability, and the potential for measurement bias due to other atmospheric constituents. Mobile isotope measurements of individual sources and in the nocturnal boundary layer have been combined to establish the fraction of the observed methane emissions that can be attributed to natural gas activities. The fraction of total methane emissions in the Denver-Julesburg basin attributed to natural gas emissions is 78 +/- 13%. In the Uinta basin, which has no other significant sources of methane, the fraction is 96% +/- 15%. In addition, results from the Barnett shale are presented, which includes a major urban center (Dallas / Ft. Worth). Methane emissions in this region are spatially highly heterogeneous. Spatially-resolved isotope and concentration measurements are interpreted using a simple emissions model to

  4. Photofield Emission Study of Metal Surfaces

    NASA Astrophysics Data System (ADS)

    Gao, Yongli

    In this thesis the efforts made to better understand the mech- anisms and to refine the apparatus of photofield emission are described. Photofield electron yield and photofield emission from surface electronic have been measured. Both demonstrate the surface sensitivity of this new technique. Analyses of laser-induced thermal effects are also reported which allows the simultaneous determination of both the temperature and workfunction of a laser illuminated surface as small as 50(ANGSTROM) in spatial extent. Theoretical calculations of photofield emission based on the relativistic elec- tronic band structure of tungsten are also carried out and the results are compared to experiment. Data from W(110) and W(111) for a number of different photon energies between 2.41eV and 3.54eV are reported. The measured yield is compared to the theoretical models of the photoexcitation process. Based on this comparison, it is concluded that the spatial variation of the vector potential (')A near the metal-vacuum interface is the dominant excitation mechanism in producing the photocurrent from a laser illuminated field emission tip. Photofield emission from surface electronic states is a unique probe to examine the radiation field near the vicinity of a metal sur- face since the surface states are localized within the first atomic layer of the surface. Studies of photofield emission from surface states on W(100), Mo(100) and Ir(111) are presented in the text. Data analysis shows that photofield emission from localized sur- face states depends predominantly on the normal component of the vector potential (')A. Laser-induced thermal effects on various surfaces of tungsten and molybdenum have been studied using field emitted electrons. Energy distributions measured by a dispersive electron energy ana- lyzer allow the temperature increase of a laser-illuminated surface to be determined to within (+OR-)10 K. In addition to estimating the tem - perature rise, small temperature

  5. Terahertz Desorption Emission Spectroscopy (THz DES) - ‘ALMA in the Lab’

    NASA Astrophysics Data System (ADS)

    Emile Auriacombe, Olivier Bruno Jacques; Fraser, Helen; Ellison, Brian; Ioppolo, Sergio; Rea, Simon

    2016-06-01

    ALMA is revolutionising our scope to identify and locate molecules that have been desorbed from ices, particularly complex organic molecules (COMS), which provide a vital link between interstellar and prebiotic chemistry. Explaining the existence of these molecules in star-forming regions relies on an empirical understanding of the chemistry that underpins their formation:- do COMS form predominantly in the solid-phase and then desorb to the gas phase, or do only “smaller” species, radials or ions desorb and then undergo gas-phase chemical reactions to generate larger COMS?-are the rotational state populations in COMS only attributable to equilibrium chemistry, or could their formation mechanisms and desorption processes affect the rotational state occupancy of these molecules, thereby directly tying certain species to solid-state origins?We have developed a novel laboratory method - THz Desorption Emission Spectroscopy (THz-DES) that combines “traditional” laboratory astrophysics high-vacuum ice experiments with a sensitive high-spectral-resolution terahertz total-power heterodyne radiometer 1,2, partially mirroring the spectral range of ALMA band 7 (275- 373 GHz). Ices are grown in situ on a cold-plate, situated in a vacuum cell, then (thermally) desorbed. The sub-mm emission spectra of the resultant gas-phase molecules are detected as a function of time, temperature, or distance from the surface. Our first THz DES results will be shown for pure and binary ice systems including H2O, N2O and CH3OH. They show good correlation with established methods e.g. TPD, with the advantage of exploiting the molecular spectroscopy to unravel surface dynamics, state-occupancy, and unequivocal molecular identification, as well as concurrently measuring desorption barriers and molecular yields. We will extend our technique to a broader frequency range, enabling us to detect radical and ion desorption, to differentiate between A and E populations of CH3OH or ortho

  6. The binuclear nickel center in the A-cluster of acetyl-CoA synthase (ACS) and two biomimetic dinickel complexes studied by X-ray absorption and emission spectroscopy

    NASA Astrophysics Data System (ADS)

    Schrapers, P.; Mebs, S.; Ilina, Y.; Warner, D. S.; Wörmann, C.; Schuth, N.; Kositzki, R.; Dau, H.; Limberg, C.; Dobbek, H.; Haumann, M.

    2016-05-01

    Acetyl-CoA synthase (ACS) is involved in the bacterial carbon oxide conversion pathway. The binuclear nickel sites in ACS enzyme and two biomimetic synthetic compounds containing a Ni(II)Ni(II) unit (1 and 2) were compared using XAS/XES. EXAFS analysis of ACS proteins revealed similar Ni-N/O/S bond lengths and Ni-Ni/Fe distances as in the crystal structure in oxidized ACS, but elongated Ni-ligand bonds in reduced ACS, suggesting more reduced nickel species. The XANES spectra of ACS and the dinickel complexes showed overall similar shapes, but less resolved pre-edge and edge features in ACS, attributed to more distorted square-planar nickel sites in particular in reduced ACS. DFT calculation of pre-edge absorption and Kβ2,5 emission features reproduced the experimental spectra of the synthetic complexes, was sensitive even to the small geometry differences in 1 and 2, and indicated low-spin Ni(II) sites. Comparison of nickel sites in proteins and biomimetic compounds is valuable for deducing structural and electronic differences in response to ligation and redox changes.

  7. Advanced Low Emissions Subsonic Combustor Study

    NASA Technical Reports Server (NTRS)

    Smith, Reid

    1998-01-01

    Recent advances in commercial and military aircraft gas turbines have yielded significant improvements in fuel efficiency and thrust-to-weight ratio, due in large part to increased combustor operating pressures and temperatures. However, the higher operating conditions have increased the emission of oxides of nitrogen (NOx), which is a pollutant with adverse impact on the atmosphere and environment. Since commercial and military aircraft are the only important direct source of NOx emissions at high altitudes, there is a growing consensus that considerably more stringent limits on NOx emissions will be required in the future for all aircraft. In fact, the regulatory communities have recently agreed to reduce NOx limits by 20 percent from current requirements effective in 1996. Further reductions at low altitude, together with introduction of limits on NOx at altitude, are virtual certainties. In addition, the U.S. Government recently conducted hearings on the introduction of federal fees on the local emission of pollutants from all sources, including aircraft. While no action was taken regarding aircraft in this instance, the threat of future action clearly remains. In these times of intense and growing international competition, the U.S. le-ad in aerospace can only be maintained through a clear technological dominance that leads to a product line of maximum value to the global airline customer. Development of a very low NOx combustor will be essential to meet the future needs of both the commercial and military transport markets, if additional economic burdens and/or operational restrictions are to be avoided. In this report, Pratt & Whitney (P&W) presents the study results with the following specific objectives: Development of low-emissions combustor technologies for advances engines that will enter into service circa 2005, while producing a goal of 70 percent lower NOx emissions, compared to 1996 regulatory levels. Identification of solution approaches to

  8. Fluorescence excitation and emission spectroscopy of the X(1)A' --> A(1)A'' system of CHI and CDI.

    PubMed

    Tao, Chong; Ebben, Carlena; Reid, Scott A

    2009-11-26

    We report on the first detailed studies of the spectroscopy of an iodocarbene, measuring fluorescence excitation and emission spectra of the X1A' --> A1A'' system of :CHI and the deuterated isotopomer :CDI. Due to similar bending and C-I stretching frequencies in the upper state, fluorescence excitation spectra of :CHI show polyads composed of members of the 2(0)(n-x)3(0)x progressions with x = 0-3. For :CDI, only progressions with x = 0, 1 are observed. Extrapolation of the 20n term energies for both isotopomers to a common origin places the electronic origin of the X1A' --> A1A'' system near 10500 cm-1, in good agreement with theoretical predictions. Rotational analysis of the 16 observed bands for CHI and 13 observed bands for :CDI yields rotational constants for the upper and lower states that are also in good agreement with theory. To investigate the controversial issue of the ground state multiplicity of :CHI, we measured single vibronic level emission spectra from many A1A'' levels. These spectra show conclusively that the ground state is a singlet, as for both isotopomers the ã3A'' origin is observed, lying well above the origin of the X1A' state. At energies above the ã3A'' origin, the spin-orbit mixing is so severe that few vibrational assignments can be made. Analysis of the emission spectra provides a lower limit on the singlet-triplet gap of 4.1 kcal mol-1, in excellent agreement with theoretical predictions.

  9. DETECTION OF REST-FRAME OPTICAL LINES FROM X-SHOOTER SPECTROSCOPY OF WEAK EMISSION-LINE QUASARS

    SciTech Connect

    Plotkin, Richard M.; Gallo, Elena; Shemmer, Ohad; Trakhtenbrot, Benny; Anderson, Scott F.; Brandt, W. N.; Luo, Bin; Schneider, Donald P.; Fan, Xiaohui; Lira, Paulina; Richards, Gordon T.; Strauss, Michael A.; Wu, Jianfeng

    2015-06-01

    Over the past 15 yr, examples of exotic radio-quiet quasars with intrinsically weak or absent broad emission line regions (BELRs) have emerged from large-scale spectroscopic sky surveys. Here, we present spectroscopy of seven such weak emission line quasars (WLQs) at moderate redshifts (z = 1.4–1.7) using the X-shooter spectrograph, which provides simultaneous optical and near-infrared spectroscopy covering the rest-frame ultraviolet (UV) through optical. These new observations effectively double the number of WLQs with spectroscopy in the optical rest-frame, and they allow us to compare the strengths of (weak) high-ionization emission lines (e.g., C iv) to low-ionization lines (e.g., Mg ii, Hβ, Hα) in individual objects. We detect broad Hβ and Hα emission in all objects, and these lines are generally toward the weaker end of the distribution expected for typical quasars (e.g., Hβ has rest-frame equivalent widths ranging from 15–40 Å). However, these low-ionization lines are not exceptionally weak, as is the case for high-ionization lines in WLQs. The X-shooter spectra also display relatively strong optical Fe ii emission, Hβ FWHM ≲ 4000 km s{sup −1}, and significant C iv blueshifts (≈1000–5500 km s{sup −1}) relative to the systemic redshift; two spectra also show elevated UV Fe ii emission, and an outflowing component to their (weak) Mg ii emission lines. These properties suggest that WLQs are exotic versions of “wind-dominated” quasars. Their BELRs either have unusual high-ionization components, or their BELRs are in an atypical photoionization state because of an unusually soft continuum.

  10. FTIR Spectroscopy for Carbon Family Study.

    PubMed

    Ţucureanu, Vasilica; Matei, Alina; Avram, Andrei Marius

    2016-11-01

    Fourier transform Infrared (FTIR) spectroscopy is a versatile technique for the characterization of materials belonging to the carbon family. Based on the interaction of the IR radiation with matter this technique may be used for the identification and characterization of chemical structures. Most important features of this method are: non-destructive, real-time measurement and relatively easy to use. Carbon basis for all living systems has found numerous industrial applications from carbon coatings (i.e. amorphous and nanocrystalline carbon films: diamond-like carbon (DLC) films) to nanostructured materials (fullerenes, nanotubes, graphene) and carbon materials at nanoscale or carbon dots (CDots). In this paper, we present the FTIR vibrational spectroscopy for the characterization of diamond, amorphous carbon, graphite, graphene, carbon nanotubes (CNTs), fullerene and carbon quantum dots (CQDs), without claiming to cover entire field.

  11. A new electron spectroscopy system for measuring electron emission from fast ion interactions with atomic, molecular, and condensed phase targets

    NASA Astrophysics Data System (ADS)

    Hawkins, Wilson L.

    A new electron spectroscopy system has been developed for measuring electron emission from gas and solid targets induced by fast ion impact. This system uses an ultrahigh-vacuum compatible cylindrical deflector analyzer, designed and fabricated in the Department of Physics at East Carolina University, to measure electron yields as a function of electron energy and emission angle for fast ions interacting with materials. The new spectroscopy system was tested in a previously existing high-vacuum target chamber that has been installed on a new beam line in the ECU Accelerator Laboratory. In addition to the new analyzer, a new data acquisition and experimental control system, based on LabVIEW computer control software, was developed and tested using an existing cylindrical mirror analyzer. Data from this system was compared to previous results to confirm the functionality of the design. Subsequently, the new analyzer was installed in the high-vacuum target chamber and tested by measuring Auger electron emission from 2 MeV protons incident on an argon gas target and comparing to well-known emission spectra. Ultimately, the new electron spectroscopy system will be used for measuring electron yields from condensed phase targets in ultrahigh-vacuum conditions in future experiments.

  12. Note: Spectrometer with multichannel photon-counting detector for beam emission spectroscopy in magnetic fusion devices

    SciTech Connect

    Lizunov, A.; Khilchenko, A.; Khilchenko, V.; Kvashnin, A.; Zubarev, P.

    2015-12-15

    A spectrometer based on a linear array photomultiplier tube (PMT) has been developed and calibrated. A 0.635 m focal length Czerny-Turner monochromator combined with a coupling optics provides an image of a narrow 0.5 nm spectral range with a resolution of 0.015 nm/channel on a 32-anode PMT. The system aims at spectroscopy of D{sub α} or H{sub α} lines emitted by a diagnostic atomic beam in a plasma (primarily a motional Stark effect diagnostics). To record a low photon flux of ∼10{sup 6} s{sup −1} per channel with the time resolution of 100 μs, a pulse counting approach has been used. Wideband amplifiers scale single-electron pulses and transmit them to a digital data processing core hardwired in a programmable logic matrix. Calibrations have shown that the aberration-limited instrument function fits to a single detector channel of 1 mm width. Pilot results of passive measurements of D{sub α} light emission from the plasma confined in a magnetic trap are presented.

  13. Observation of iron spin-states using tabletop x-ray emission spectroscopy and microcalorimeter sensors

    NASA Astrophysics Data System (ADS)

    Joe, Y. I.; O'Neil, G. C.; Miaja-Avila, L.; Fowler, J. W.; Jimenez, R.; Silverman, K. L.; Swetz, D. S.; Ullom, J. N.

    2016-01-01

    X-ray emission spectroscopy (XES) is a powerful probe of the electronic and chemical state of elemental species embedded within complex compounds. X-ray sensors that combine high resolving power and high collecting efficiency are desirable for photon-starved XES experiments such as measurements of dilute, gaseous, and radiation-sensitive samples, time-resolved measurements, and in-laboratory XES. To assess whether arrays of cryogenic microcalorimeters will be useful in photon-starved XES scenarios, we demonstrate that these emerging energy-dispersive sensors can detect the spin-state of 3d electrons of iron in two different compounds, Fe2O3 and FeS2. The measurements were conducted with a picosecond pulsed laser-driven plasma as the exciting x-ray source. The use of this tabletop source suggests that time-resolved in-laboratory XES will be possible in the future. We also present simulations of {{K}}α and {{K}}β spectra that reveal the spin-state sensitivity of different combinations of sensor resolution and accumulated counts. These simulations predict that our current experimental apparatus can perform time-resolved XES measurements on some samples with a measurement time of a few 10 s of hours per time delay.

  14. Design of a beam emission spectroscopy diagnostic for negative ions radio frequency source SPIDER

    SciTech Connect

    Zaniol, B.; Pasqualotto, R.; Barbisan, M.

    2012-04-15

    A facility will be built in Padova (Italy) to develop, commission, and optimize the neutral beam injection system for ITER. The full scale prototype negative ion radio frequency source SPIDER, featuring up to 100 kV acceleration voltage, includes a full set of diagnostics, required for safe operation and to measure and optimize the beam performance. Among them, beam emission spectroscopy (BES) will be used to measure the line integrated beam uniformity, divergence, and neutralization losses inside the accelerator (stripping losses). In the absence of the neutralization stage, SPIDER beam is mainly composed by H{sup -} or D{sup -} particles, according to the source filling gas. The capability of a spectroscopic diagnostic of an H{sup -} (D{sup -}) beam relies on the interaction of the beam particles with the background gas particles. The BES diagnostic will be able to acquire the H{sub {alpha}} (D{sub {alpha}}) spectrum from up to 40 lines of sight. The system is capable to resolve stripping losses down to 2 keV and to measure beam divergence with an accuracy of about 10%. The design of this diagnostic is reported, with discussion of the layout and its components, together with simulations of the expected performance.

  15. Ultra-nonlocality in density functional theory for photo-emission spectroscopy

    SciTech Connect

    Uimonen, A.-M.; Stefanucci, G.; Leeuwen, R. van

    2014-05-14

    We derive an exact expression for the photocurrent of photo-emission spectroscopy using time-dependent current density functional theory (TDCDFT). This expression is given as an integral over the Kohn-Sham spectral function renormalized by effective potentials that depend on the exchange-correlation kernel of current density functional theory. We analyze in detail the physical content of this expression by making a connection between the density-functional expression and the diagrammatic expansion of the photocurrent within many-body perturbation theory. We further demonstrate that the density functional expression does not provide us with information on the kinetic energy distribution of the photo-electrons. Such information can, in principle, be obtained from TDCDFT by exactly modeling the experiment in which the photocurrent is split into energy contributions by means of an external electromagnetic field outside the sample, as is done in standard detectors. We find, however, that this procedure produces very nonlocal correlations between the exchange-correlation fields in the sample and the detector.

  16. Note: Spectrometer with multichannel photon-counting detector for beam emission spectroscopy in magnetic fusion devices

    NASA Astrophysics Data System (ADS)

    Lizunov, A.; Khilchenko, A.; Khilchenko, V.; Kvashnin, A.; Zubarev, P.

    2015-12-01

    A spectrometer based on a linear array photomultiplier tube (PMT) has been developed and calibrated. A 0.635 m focal length Czerny-Turner monochromator combined with a coupling optics provides an image of a narrow 0.5 nm spectral range with a resolution of 0.015 nm/channel on a 32-anode PMT. The system aims at spectroscopy of Dα or Hα lines emitted by a diagnostic atomic beam in a plasma (primarily a motional Stark effect diagnostics). To record a low photon flux of ˜106 s-1 per channel with the time resolution of 100 μs, a pulse counting approach has been used. Wideband amplifiers scale single-electron pulses and transmit them to a digital data processing core hardwired in a programmable logic matrix. Calibrations have shown that the aberration-limited instrument function fits to a single detector channel of 1 mm width. Pilot results of passive measurements of Dα light emission from the plasma confined in a magnetic trap are presented.

  17. Synthetic diagnostic for the beam emission spectroscopy diagnostic using a full optical integration

    NASA Astrophysics Data System (ADS)

    Hausammann, L.; Churchill, R. M.; Shi, L.

    2017-02-01

    The beam emission spectroscopy (BES) diagnostic is used to measure fluctuations of electron density in the edge and core of fusion plasmas, and is a key in understanding turbulence in a plasma reactor. A synthetic BES diagnostic for the turbulence simulation code XGC1 has been developed using a realistic neutral beam model and an optical system easily adaptable to different kinds of tokamaks. The beam is modeled using multiple beam energy components, each one with a fraction of the total energy and their own mass and energy (mono-energetic components). The optical system consists of a lens focusing a bundle of optical fibers and resulting in a 2D measurement. The synthetic diagnostic gives similar correlation functions and behaviour of the turbulences than the usual methods that do not take into account the full 3D optical effects. The results, based on a simulation of XGC1, contain an analysis of the correlation (in space and time), a comparison of different approximations possible and their importance in accurately modeling the BES diagnostic.

  18. Imaging molecular adsorption and desorption dynamics on graphene using terahertz emission spectroscopy

    NASA Astrophysics Data System (ADS)

    Sano, Y.; Kawayama, I.; Tabata, M.; Salek, K. A.; Murakami, H.; Wang, M.; Vajtai, R.; Ajayan, P. M.; Kono, J.; Tonouchi, M.

    2014-08-01

    Being an atomically thin material, graphene is known to be extremely susceptible to its environment, including defects and phonons in the substrate on which it is placed as well as gas molecules that surround it. Thus, any device design using graphene has to take into consideration all surrounding components, and device performance needs to be evaluated in terms of environmental influence. However, no methods have been established to date to readily measure the density and distribution of external perturbations in a quantitative and non-destructive manner. Here, we present a rapid and non-contact method for visualizing the distribution of molecular adsorbates on graphene semi-quantitatively using terahertz time-domain spectroscopy and imaging. We found that the waveform of terahertz bursts emitted from graphene-coated InP sensitively changes with the type of atmospheric gas, laser irradiation time, and ultraviolet light illumination. The terahertz waveform change is explained through band structure modifications in the InP surface depletion layer due to the presence of localized electric dipoles induced by adsorbed oxygen. These results demonstrate that terahertz emission serves as a local probe for monitoring adsorption and desorption processes on graphene films and devices, suggesting a novel two-dimensional sensor for detecting local chemical reactions.

  19. Improvement of photomask CD uniformity using spatially resolved optical emission spectroscopy

    NASA Astrophysics Data System (ADS)

    Jung, Junhwa; Kim, Youngkeun; Jang, Il-Yong; Kim, Byung-Gook; Jeon, Chan-Uk; Kang, Minwook; Lee, Changmin; Hahn, Jae W.

    2016-10-01

    According to the design rule shrinkage, more precise control of mask CD, including mean to target and uniformity, is required in lithography process. Since dry etching is one of the most critical processes to determine CD qualities in photomask, optical emission spectroscopy (OES) to monitor plasma status during dry etching process could be useful. However, it is not possible to obtain distributional information of plasma with a conventional OES tool because the OES acquires totally integrated signals of light from the chamber. To overcome the limit of OES, we set up a spatially resolved (SR)-OES tool and measure the distribution of radicals in plasma during dry etch process. The SR-OES consists of a series of lenses, apertures, and a pinhole as a spatial filter which enable us to focus on certain area in the chamber, to extract the emitted light from plasma, and to perform the spectroscopic analysis. The Argon based actinometry combined with SR-OES shows spatially distinguished peaks related to the etch rate of Chromium on photomask. In this paper, we present experimental results of SR-OES installed on a commercial photomask dry etcher and discuss its practical effectiveness by correlation of the results with chamber etch rate.

  20. Heuristic modeling of spectral plasma emission for laser-induced breakdown spectroscopy

    SciTech Connect

    Wester, Rolf; Noll, Reinhard

    2009-12-15

    A heuristic model was developed to describe the spectral emission of laser-induced plasmas generated for laser-induced breakdown spectroscopy under the assumption that the composition of the plasma and the plasma state is known. The plasma is described by a stationary spherical shell model surrounded by an ambient gas, which partially absorbs the emitted radiation. The radiation transport equation is used to calculate the spectrum emitted by the plasma. Simulations of a multiline iron spectrum and a self-reversed Al line are compared with experimental spectra. For the iron spectrum, the degree of congruence is moderate to good, which may be attributed to a lack of precise atomic and Stark broadening data as well as a simplified plasma model. The line profile of the Al resonance line with self reversal can be simulated with a high degree of agreement. Simulated spectra of a steel sample in the vacuum ultraviolet spectral range demonstrate the strong influence of the ambient atmosphere in the spectral range between 178 and 194 nm. The number of free parameters of the plasma model of 8 can be further reduced down to 3, taking into account the integral parameters of the plasma that are accessible experimentally.

  1. Assessment of diabetic neuropathy with emission tomography and magnetic resonance spectroscopy.

    PubMed

    Rao, Harshvardhan; Gaur, Neeraj; Tipre, Dnyanesh

    2017-04-01

    Diabetic neuropathies (DNs) are nerve-damaging disorders associated with diabetes. They are commonly attributed to peripheral nerves and primarily affect the limbs of the patient. They cause altered sensitivity to external stimuli along with loss in balance and reflexes of the affected patient. DNs are associated with a variety of clinical manifestations including autonomic failure and are caused by poor management of blood sugar levels. Imaging modalities provide vital information about early physiological changes in DNs. This review summarizes contributions by various teams of scientists in developing imaging methods to assess physiological changes in DNs and ongoing clinical trials where imaging modalities are applied to evaluate therapeutic intervention in DNs. Development of PET, single photon emission computed tomography, and magnetic resonance spectroscopy methods over the past 20 years are reviewed in the diagnostic assessment of DNs. Abnormal radiotracer pharmacokinetics and neurometabolite spectra in affected organs confirm physiological abnormalities in DN. With the use of the Siemens Biograph mMR and GE Signa - 60 cm (PET/MRI scanner), simultaneous acquisition of physiological and anatomical information could enhance understanding of DNs and accelerate drug development.

  2. Updates on Optical Emission Spectroscopy & Langmuir Probe Investigations on the Helicon Plasma Experiment (HPX)

    NASA Astrophysics Data System (ADS)

    Karama, Jackson; Frank, John; Azzari, Phillip; Hopson, Jordan; James, Royce; Duke-Tinson, Omar; Paolino, Richard; Sandri, Eva; Sherman, Justin; Wright, Eva; Turk, Jeremy

    2015-11-01

    HPX is developing a to shorter lifetime (20 - 30 ns) more reproducible plasma at the Coast Guard Academy Plasma Laboratory (CGAPL). Once achieved, spectral and particle probes will help to verify plasma mode transitions to the W-mode. These optical probes utilize movable filters, and ccd cameras to gather data at selected spectral frequency bands. Once corrections for the RF field are in place for the Langmuir probe, raw data will be collected and used to measure the plasma's density, temperature, and potentially the structure and behavior during experiments. Direct measurements of plasma properties can be determined with modeling and by comparison with the state transition tables, both using Optical Emission Spectroscopy (OES). The spectral will add to HPX's data collection capabilities and be used in conjunction with the particle probes, and Thomson Scattering device to create a robust picture of the internal and external plasma parameters on HPX. Progress on the implementation of the OES and Langmuir probes will be reported. Supported by U.S. DEPS Grant [HEL-JTO] PRWJFY15.

  3. Updates on the Optical Emission Spectroscopy and Thomson Scattering Investigations on the Helicon Plasma Experiment (HPX)

    NASA Astrophysics Data System (ADS)

    Duke-Tinson, Omar; Karama, Jackson; Azzari, Phillip; Royce, James; Page, Eric; Schlank, Carter; Sherman, Justin; Stutzman, Brooke; Zuniga, Jonathan

    2014-10-01

    HPX at the Coast Guard Academy Plasma Laboratory (CGAPL) have set up spectral probes to verify plasma mode transitions to the W-mode. These optical probes utilize movable filters, and ccd cameras to gather data at selected spectral frequency bands. Raw data collected will be used to measure the plasma's relative density, temperature, structure, and behavior during experiments. Direct measurements of the plasma's properties can be determined through modeling and by comparison with the state transition tables, using Optical Emission Spectroscopy (OES). The spectral probes will take advantage of HPX's magnetic field structure to define and measure the plasma's radiation temp as a function of time and space. In addition, the Thomson Scattering (TS) device will measure internal temperature and density data as the HPX plasma transitions through capacitive and inductive modes while developing into helicon plasma. Currently CGAPL is focused on building its laser beam transport and scattered light collection optical systems. Recently, HPX has acquired an Andor ICCD spectrometer for the spectral analysis. Data collected by the TS system will be logged in real time by CGAPL's Data Acquisition (DAQ) system with LabView remote access. Further progress on HPX will be reported. Supported by U.S. DEPS Grant [HEL-JTO] PRWJFY13.

  4. [Research on the atomic emission spectroscopy of atmospheric pressure plasma process].

    PubMed

    Jin, Jiang; Li, Na; Xu, Lu; Wang, Bo; Jin, Hui-Liang

    2013-02-01

    In the reaction of the atmospheric pressure plasma process, the heat stable process of the atmospheric pressure plasma jet has a direct impact on the removal rate, CF4 is the provider of active F* atom, O2 is important auxiliary gas, and they play an important role in the process. In order to research the rule of the concentration of the 3 parameters upon the atmospheric pressure plasma processing, the atmospheric pressure plasma jet was used for processing and the spectrometer was used to monitor the changes in the process. The experiment indicates that: when the heat is stable, the concentration of the active F* atom essentially remains unchanged; with increasing the concentration of gas CF4, the spectrum of the active F* atom has self-absorption phenomena, so using the atomic emission spectroscopy method to monitor the changes in the concentration of active F* atom generated by CF4 is not completely exact; because O2 can easily react with the dissociation product of CF4, which inhibits the compound of the active F* atom, so in a certain range with increasing the concentration of gas O2, the concentration of the active F* atom becomes strong.

  5. Titanium density analysed by optical absorption and emission spectroscopy in a dc magnetron discharge

    NASA Astrophysics Data System (ADS)

    Gaillard, M.; Britun, N.; Kim, Yong M.; Han, Jeon G.

    2007-02-01

    This paper presents an optical diagnostic examination of dc planar magnetron discharge used for titanium deposition at 30 mTorr in argon bulk gas. The results were obtained by optical absorption (OAS) and emission (OES) spectroscopy for two distances from the target without substrate. The absolute density of titanium in the ground and metastable states at 4 cm from the target ranged, respectively, between 8 × 1010 cm-3 and 1012 cm-3 and between 6 × 1010 cm-3 and 3 × 1011 cm-3, in the range 0.2-1.0 A. OES results were used to prepare an assumed interpretation in terms of differences in loss mechanisms, mainly by either diffusion towards the walls for all particles at 8 cm from the target or collision losses for non-radiative species at 4 cm from the target, except for the titanium ground state. This was confirmed by our results of the argon metastable density measurement at 4 cm which was constant at around 7 × 1010 cm-3 with discharge current.

  6. Near-infrared spectroscopy of planetary nebulae: How strong is the H2 emission?

    NASA Technical Reports Server (NTRS)

    Dinerstein, H. L.; Carr, J.; Harvey, P. M.; Lester, D. F.

    1986-01-01

    In an effort to understand the systematics of the H2 emission from planetary nebulae, a program of near-infared spectroscopy using the University of Texas infrared reticon spectrometer was started. This instrument has a 1x32 element InSb photodiode array as a detector. All of the observations reported were made on the McDonald Observatory 2.7 m telescope, with spectra resolving power lambda/delta lambda = 600. The spectral coverage allows the measurement strengths of Brackett gamma He I 2.113 microns, HE II 2.189 microns and the v = 1=0 S(1) line of H2 at 2.122 microns. One of the most important advantages of this instrument is that we are able to resolve H2 from the adjacent He I line. Most previous observations of planetaries have been made at spectral resolving powers of about 100, which blend these lines. The contribution of the He I line has generally been dismissed as being unimportant, but we show that this may not be valid. Our higher resolving power also improves the line-to-continuum contrast; in some cases, the continuum is the limiting factor in detecting faint lines.

  7. Optical Emission Spectroscopy in PECVD Helps Modulate Key Features in Biofunctional Coatings for Medical Implants

    NASA Astrophysics Data System (ADS)

    Santos, Miguel; Michael, Praveesuda; Filipe, Elysse; Wise, Steven; Bilek, Marcela; University of Sydney Collaboration

    2015-09-01

    We explore the use of optical emission spectroscopy (OES) diagnostic tools as a process feedback control strategy in plasma-assisted deposition of biofunctional coatings. Hydrogenated carbon nitride coatings are deposited on medical-grade metallic substrates using radio-frequency (rf) discharges sustained in C2H2/N2/Ar gaseous mixtures. The discharge is generated by capacitively coupling the rf power (supplied at f = 13.56 MHz) to the plasma and the substrates are electrically biased using a pulse generator to provide microsecond square profiled pulses at voltages in the range |Vbias| = 250 V - 1000 V. Nitrogen content and CN bonding configurations in the coatings follow similar trends to those of CN radicals and nitrogen molecular ions in the discharge. OES is used as a non-intrusive diagnostic technique to identify a suitable window of process parameters and ultimately achieve biofunctional interfaces compatible with current clinical demands. Importantly, we demonstrate that key features of the coatings can be modulated and made suitable for blood and/or tissue contacting medical implants, such as coronary stents and orthopaedic implants. The coatings are mechanically robust, inherently non-thrombogenic and can be readily modified, enabling an easy functionalization through the immobilization of biological molecules in a bioactive conformation.

  8. Deep level study of Mg-doped GaN using deep level transient spectroscopy and minority carrier transient spectroscopy

    NASA Astrophysics Data System (ADS)

    Duc, Tran Thien; Pozina, Galia; Amano, Hiroshi; Monemar, Bo; Janzén, Erik; Hemmingsson, Carl

    2016-07-01

    Deep levels in Mg-doped GaN grown by metal organic chemical vapor deposition (MOCVD), undoped GaN grown by MOCVD, and halide vapor phase epitaxy (HVPE)-grown GaN have been studied using deep level transient spectroscopy and minority charge carrier transient spectroscopy on Schottky diodes. One hole trap, labeled HT1, was detected in the Mg-doped sample. It is observed that the hole emission rate of the trap is enhanced by increasing electric field. By fitting four different theoretical models for field-assisted carrier emission processes, the three-dimensional Coulombic Poole-Frenkel (PF) effect, three-dimensional square well PF effect, phonon-assisted tunneling, and one-dimensional Coulombic PF effect including phonon-assisted tunneling, it is found that the one-dimensional Coulombic PF model, including phonon-assisted tunneling, is consistent with the experimental data. Since the trap exhibits the PF effect, we suggest it is acceptorlike. From the theoretical model, the zero field ionization energy of the trap and an estimate of the hole capture cross section have been determined. Depending on whether the charge state is -1 or -2 after hole emission, the zero field activation energy Ei 0 is 0.57 eV or 0.60 eV, respectively, and the hole capture cross section σp is 1.3 ×10-15c m2 or 1.6 ×10-16c m2 , respectively. Since the level was not observed in undoped GaN, it is suggested that the trap is associated with an Mg related defect.

  9. VIMOS integral field spectroscopy of blue compact galaxies. I. Morphological properties, diagnostic emission-line ratios, and kinematics

    NASA Astrophysics Data System (ADS)

    Cairós, L. M.; Caon, N.; Weilbacher, P. M.

    2015-05-01

    Context. Blue compact galaxies (BCG) are gas-rich, low-luminosity, low-metallicity systems that undergo a violent burst of star formation. These galaxies offer us a unique opportunity to investigate collective star formation and its effects on galaxy evolution in a relatively simple environment. Spatially resolved spectrophotometric studies of BCGs are essential for a better understanding of the role of starburst-driven feedback processes on the kinematical and chemical evolution of low-mass galaxies near and far. Aims: We carry out an integral field spectroscopic study of a sample of BCGs, with the aim of probing the morphology, kinematics, dust extinction, and excitation mechanisms of their warm interstellar medium. Methods: Eight BCGs were observed with the VIMOS integral field unit at the Very Large Telescope using blue and orange grisms in high-resolution mode. At a spatial sampling of 0''&dotbelow;67 per spaxel, we covered about 30″ × 30″ on the sky, with a wavelength range of 4150...7400 Å. Emission lines were fitted with a single Gaussian profile to measure their wavelength, flux, and width. From these data we built two-dimensional maps of the continuum and the most prominent emission-lines, as well as diagnostic line ratios, extinction, and kinematic maps. Results: An atlas has been produced with the following: emission-line fluxes and continuum emission; ionization, interstellar extinction, and electron density maps from line ratios; velocity and velocity dispersion fields. From integrated spectroscopy, it includes tables of the extinction corrected line fluxes and equivalent widths, diagnostic-line ratios, physical parameters, and the abundances for the brightest star-forming knots and for the whole galaxy. Based on observations made with ESO Telescopes at the Paranal Observatory under program ID 079.B-0445.The reduced datacubes and their error maps (FITS files) are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp

  10. Tissue differentiation by means of high resolution optical emission spectroscopy during electrosurgical intervention

    NASA Astrophysics Data System (ADS)

    Bürger, Ines; Scharpf, Marcus; Hennenlotter, Jörg; Nüßle, Daniela; Spether, Dominik; Neugebauer, Alexander; Bibinov, Nikita; Stenzl, Arnulf; Fend, Falko; Enderle, Markus; Awakowicz, Peter

    2017-01-01

    Electrosurgery is the use of radio-frequency electric current for the cutting of biological tissue e.g. for resection of tumour tissue. In this work, the optical emission of plasma being generated during the electrosurgical procedure is investigated with a high resolution echelle spectrometer to find differences between tumour tissue and normal renal tissue in a pre-clinical ex vivo study. Trace elements like zinc, iron, copper and cadmium are present in the tissue spectra as well as the electrolytes magnesium, calcium, sodium and potassium and some diatomic molecules such as hydroxyl radical, cyano radical, dicarbon, nitrogen monohydride and molecular nitrogen which are mainly dissociated from polyatomic molecules. With the atomic emission line of cadmium at 228.8 nm the treated tissue can be differentiated in tumorous and healthy tissue with correct assignment of 95% for tumour tissue and 92% for normal renal tissue.

  11. Infrared spectroscopy study of irradiated PVDF

    SciTech Connect

    Chappa, Veronica; Grosso, Mariela del; Garcia Bermudez, Gerardo; Behar, Moni

    2007-10-26

    The effects induced by 1 MeV/amu ion irradiations were compared to those induced by 4-12 MeV/amu irradiations. Structural analysis with infrared spectroscopy (FTIR) was carried out on PVDF irradiated using C and He beams with different fluences. From these spectra it was observed, as a function of fluence, an overall destruction of the polymer, amorphization of the crystalline regions and the creation of in-chain unsaturations. The track dimensions were determined using a previously developed Monte Carlo simulation code and these results were compared to a semiempirical model.

  12. EUVE Spectroscopy of Comet Hyakutake: First Detection of Solar Wind Charge Transfer Emissions

    NASA Astrophysics Data System (ADS)

    Krasnopolsky, V. A.; Mumma, M. J.

    2000-10-01

    The ROSAT and EUVE observations of comet Hyakutake in 1996 revealed a puzzling X-ray emission. That comet appeared to be a more efficient emitter of X-rays than the Moon by a factor of 80,000. Currently our EUVE database includes eight observations of comets, and soft X-ray emissions have been detected in five of those observations. The measured soft X-ray luminosities are proportional to r3/2Qgas with the efficiency of (6.4+/- 0.9)10-5 AU3/2 and therefore favor a gas-related mechanism. The observed behavior of the brightness maxima and spatial distributions of soft X-ray emissions indicate charge transfer of solar wind heavy ions as the only viable excitation process. However, a final and crucial test for the X-ray excitation process should be made by spectroscopy. We extracted three spectra from our EUVE observations of comet Hyakutake. These spectra cover the ranges of 80-180, 170-360, and 300-700 Å. Due to the close flyby of the comet at 0.1 AU, (1-3)104 photons were collected in each spectrum, that is, more by two orders of magnitude than in the previously published spectra. Despite very good dispersion of the EUVE spectrometers, the great angular extent of the comet reduced the resolving power to 10 in our spectra. The spectra revealed for the first time emission lines of multiple charged ions which present a direct evidence for solar wind charge transfer excitation. The most prominent lines are O4+ 215 Å, C4+ 249 Å, He+ 304 Å, and Ne7+ 448 Å. Some other lines, which are of comparable strength, are blended. The photon luminosity of charge exchange at energy below 100 eV (124 Å) exceeds that above 100 eV by a factor of 2, and the mean total quantum yield is 4 photons per heavy ion. The detected O+ lines at 538/539, 617, and 430/442 Å are excited by photoionization of atomic oxygen similar to that in Earth's dayglow. The observed depletion of neon by more than a factor 2600 relative to the solar abundance confirm the current view that Oort cloud comets

  13. A Chemical Detector for Gas Chromatography Using Pulsed Discharge Emission Spectroscopy on a Microchip

    NASA Astrophysics Data System (ADS)

    Luo, X.; Zhu, W.; Mitra, B.; Liu, J.; Liu, T.; Fan, X.; Gianchandani, Y.

    2011-12-01

    There is increasing interest in miniaturized systems for chemical analysis in harsh environments. Chemical detection by emission spectroscopy of on-chip microdischarges [1-3] can be performed at >200°C [4], suggesting utility inspace exploration, volcanic monitoring, and oil well monitoring. This abstract describes the first use of pulsed microdischarge spectroscopy for gas chromatography (GC).This effort supports NASA interests in monitoring closed-loop life support systems for spacecraft. The microdischarge occurs on a 1cm2 glass chip (Fig. 1a), with thin-film Ni electrodes separated by 160μm. A glass lid with a grooved gas-flow channel, and inlet/outlet capillary tubes are epoxy-sealed to the chip. Located downstream of the 1.7m-long, RTX-1-coated, GC separation column, the microdischarge chip is read by a spectrometer. In a typical experiment (Fig. 1b), a mixture of acetone 3.6μg, 1-hexanol 2.8μg and nitrobenzene 3.0μg, is injected, with He carrier gas at 1.56sccm, through the GC. Acetone elutes quickly while nitrobenzene is slower. Microdischarges are triggered at 0.5Hz for 6 min., and 0.04Hz thereafter. Each microdischarge consumes ≈8mJ; the average power is ≈1.14mW. The spectrum (Fig. 1b, inset) shows that the 388nm peak, representing CN/CH fragments [5], is enhanced by carbon compounds. Its strength relative to the 588nm peak of He provides a chromatogram. Fig. 1b also shows a benchmark result from a commercial flame ionization detector (FID). The differences in elution time are attributed to differences in the gas flow paths for the two detectors [1]. REFERENCES [1] Eijkel et al, Anal. Chem, 2000 [2] Mitra et al, IEEE Trans Plasma Sci, 2008 [3] Mitra et al, IEEE Sensors, 2008 [4] Wright et al, APL, 2009 [5] Pearse et al, The Identification of Molecular Spectra, 1963

  14. Optical emission spectroscopy of microwave-plasmas at atmospheric pressure applied to the growth of organosilicon and organotitanium nanopowders

    NASA Astrophysics Data System (ADS)

    Kilicaslan, A.; Levasseur, O.; Roy-Garofano, V.; Profili, J.; Moisan, M.; Côté, C.; Sarkissian, A.; Stafford, L.

    2014-03-01

    An atmospheric-pressure plasma sustained by an electromagnetic surface wave (SW) in the microwave regime combined with a bubbler/flash evaporator for the injection of liquid precursors was used to produce organosilicon and organotitanium nanopowders. Following the addition of hexamethyldisiloxane (HMDSO) vapors in the nominally pure argon plasma, optical emission spectra revealed the apparition of strong C2 molecular bands along with Si and Balmer H emission lines. Such features were not observed in our atmospheric-pressure Ar/HMDSO discharges controlled by dielectric barriers, indicating that microwave plasmas are characterized by much higher fragmentation levels of the precursors due to much higher electron densities. Emission spectra from the Ar/HMDSO SW plasma further showed a high-intensity continuum, the intensity of which decreased with time as powders started to form on the discharge tube walls. In presence of titanium isopropoxide (TTIP) vapors in the nominally pure Ar plasma, the emission was dominated by Ar and Ti lines, with no trace of carbon and no continuum. Fourier-Transform Infrared (FTIR) Spectroscopy of the powders formed in Ar/HMDSO plasmas showed very strong Si-(CH3)x and O-Si-(CH3)x bands, which is consistent with the formation of silicon oxycarbide. Transmission Electron Microscopy (TEM) further showed tube and sheet-like nanofeatures as well as larger structures consisting of agglomerated primary clusters. On the other hand, introduction of O2 in Ar/HMDSO plasmas produced only round-like nanoparticles with strong Si-O-Si bands and no trace of carbon, consistent with the formation of SiOx. The average size of the silica nanoparticles was 50 nm. FTIR spectra of powders formed in Ar/TTIP plasmas showed strong Ti-O signals, even without the addition of O2 in the gas phase. Corresponding TEM analysis showed nano- and agglomerated features comparable to those obtained in Ar/HMDSO although the average size of the titanate nanoparticles was smaller

  15. Optical emission spectroscopy of microwave-plasmas at atmospheric pressure applied to the growth of organosilicon and organotitanium nanopowders

    SciTech Connect

    Kilicaslan, A.; Levasseur, O.; Roy-Garofano, V.; Profili, J.; Moisan, M.; Stafford, L.; Côté, C.; Sarkissian, A.

    2014-03-21

    An atmospheric-pressure plasma sustained by an electromagnetic surface wave (SW) in the microwave regime combined with a bubbler/flash evaporator for the injection of liquid precursors was used to produce organosilicon and organotitanium nanopowders. Following the addition of hexamethyldisiloxane (HMDSO) vapors in the nominally pure argon plasma, optical emission spectra revealed the apparition of strong C{sub 2} molecular bands along with Si and Balmer H emission lines. Such features were not observed in our atmospheric-pressure Ar/HMDSO discharges controlled by dielectric barriers, indicating that microwave plasmas are characterized by much higher fragmentation levels of the precursors due to much higher electron densities. Emission spectra from the Ar/HMDSO SW plasma further showed a high-intensity continuum, the intensity of which decreased with time as powders started to form on the discharge tube walls. In presence of titanium isopropoxide (TTIP) vapors in the nominally pure Ar plasma, the emission was dominated by Ar and Ti lines, with no trace of carbon and no continuum. Fourier-Transform Infrared (FTIR) Spectroscopy of the powders formed in Ar/HMDSO plasmas showed very strong Si-(CH{sub 3}){sub x} and O-Si-(CH{sub 3}){sub x} bands, which is consistent with the formation of silicon oxycarbide. Transmission Electron Microscopy (TEM) further showed tube and sheet-like nanofeatures as well as larger structures consisting of agglomerated primary clusters. On the other hand, introduction of O{sub 2} in Ar/HMDSO plasmas produced only round-like nanoparticles with strong Si-O-Si bands and no trace of carbon, consistent with the formation of SiO{sub x}. The average size of the silica nanoparticles was 50 nm. FTIR spectra of powders formed in Ar/TTIP plasmas showed strong Ti-O signals, even without the addition of O{sub 2} in the gas phase. Corresponding TEM analysis showed nano- and agglomerated features comparable to those obtained in Ar/HMDSO although the

  16. Bright emissive core-shell spherical microparticles for shock compression spectroscopy

    SciTech Connect

    Christensen, James M.; Banishev, Alexandr A.; Dlott, Dana D.

    2014-07-21

    Experiments were performed to study the response to shock compression of rhodamine 6G (R6G) dye encapsulated in 1.25 μm diameter silica microspheres. When R6G was encapsulated in microspheres, the emission intensity under steady-state irradiation (the brightness) was 3.4 times greater than the same dye in solution (the free dye). At least part of the brightness improvement was caused by an enhanced radiative rate. When the microspheres were embedded in poly-methylmethacrylate subjected to planar shocks in the 3–8.4 GPa range by laser-driven flyer plates, the dye emission redshifted and lost intensity. The dye emission redshift represents an instantaneous response to changes in the local density. In free dye samples, the shock-induced intensity loss had considerably slower rise times and fall times than the redshift. When dye was encapsulated in microspheres, the time dependence of the intensity loss matched the redshift almost exactly over a range of shock pressures and durations. The faster response to shock of dye in silica microspheres was explained by dye photophysics. The microsphere environment decreased the singlet state lifetime, which decreased the rise time, and it also decreased the triplet state lifetime, which decreased the fall time. Since it is much easier and more convenient to make measurements of intensity rather than spectral shift, these microspheres represent a substantial improvement in optical sensors to monitor shock compression of microstructured materials.

  17. Development of a polarization-modulation spectroscopy system for the temporally resolved measurement of linear polarization in plasma emission

    NASA Astrophysics Data System (ADS)

    Yasui, Kenji; Shikama, Taiichi; Higashi, Takanori; Hasuo, Masahiro

    2016-10-01

    A system to measure linear polarization in the HeI 21P-31D emission line (667.8 nm) was developed for application to plasma polarization spectroscopy. To verify the system performance, the normalized Stokes parameters were evaluated. A measurement error of less than 1% with a time resolution of 1 ms was achieved for monochromatic light in the state of complete linear polarization.

  18. High-resolution X-ray emission spectroscopy with transition-edge sensors: present performance and future potential.

    PubMed

    Uhlig, J; Doriese, W B; Fowler, J W; Swetz, D S; Jaye, C; Fischer, D A; Reintsema, C D; Bennett, D A; Vale, L R; Mandal, U; O'Neil, G C; Miaja-Avila, L; Joe, Y I; El Nahhas, A; Fullagar, W; Gustafsson, F Parnefjord; Sundström, V; Kurunthu, D; Hilton, G C; Schmidt, D R; Ullom, J N

    2015-05-01

    X-ray emission spectroscopy (XES) is a powerful element-selective tool to analyze the oxidation states of atoms in complex compounds, determine their electronic configuration, and identify unknown compounds in challenging environments. Until now the low efficiency of wavelength-dispersive X-ray spectrometer technology has limited the use of XES, especially in combination with weaker laboratory X-ray sources. More efficient energy-dispersive detectors have either insufficient energy resolution because of the statistical limits described by Fano or too low counting rates to be of practical use. This paper updates an approach to high-resolution X-ray emission spectroscopy that uses a microcalorimeter detector array of superconducting transition-edge sensors (TESs). TES arrays are discussed and compared with conventional methods, and shown under which circumstances they are superior. It is also shown that a TES array can be integrated into a table-top time-resolved X-ray source and a soft X-ray synchrotron beamline to perform emission spectroscopy with good chemical sensitivity over a very wide range of energies.

  19. Characterization of a high current pulsed arc using optical emission spectroscopy

    NASA Astrophysics Data System (ADS)

    Sousa Martins, R.; Zaepffel, C.; Chemartin, L.; Lalande, Ph; Soufiani, A.

    2016-10-01

    In this paper, we present the investigation realized on an experimental setup that simulates an arc column subjected to the transient phase of a lightning current waveform in laboratory conditions. Optical emission spectroscopy is employed to assess space- and time-resolved properties of this high current pulsed arc. Different current peak levels are utilised in this work, ranging from 10 kA to 100 kA, with a peak time around 15 µs. Ionic lines of nitrogen and oxygen are used to determine the radial profiles of temperature and electron density of the arc channel over time from 2 µs to 36 µs. A combination of 192 N II and O II lines is considered in the calculation of the bound-bound contribution of the absorption coefficient of the plasma channel. Calculations of the optical thickness showed that self-absorption of these ionic lines in the arc column is important. To obtain temperature and electron density profiles in the arc, we solved the radiative transfer equation across the channel under an axisymmetric assumption and considering the channel formed by uniform concentric layers. For the 100 kA current peak level, the temperature reaches more than 38 000 K and the electron density reaches 5  ×  1018 cm-3. The pressure inside the channel is calculated using the air plasma composition at local thermodynamic equilibrium, and reaches 45 bar. The results are discussed and utilised to estimate the electrical conductivity of the arc channel.

  20. The use of inductively coupled plasma-atomic emission spectroscopy (ICP-AES) in the determination of lithium in cleaning validation swabs.

    PubMed

    Lewen, Nancy; Nugent, Dennis

    2010-09-05

    The pharmaceutical industry is required to perform cleaning validation studies to verify that equipment used in the manufacture of pharmaceuticals is adequately cleaned from one product or process to the next. Typically, these cleaning validation studies require an analytical method that uses some form of chromatographic technique. In the case of products that may have an inorganic constituent, however, if can often be easier to verify the cleanliness of equipment by using a non-chromatographic technique. A method is described to certify the cleanliness of processing equipment by determining lithium in cleaning validation swabs using inductively coupled plasma-atomic emission spectroscopy (ICP-AES).

  1. Chamber study of polychlorinated biphenyl (PCB) emissions ...

    EPA Pesticide Factsheets

    The sorption of airborne polychlorinated biphenyls (PCBs) by twenty building materials and their subsequent re-emission (desorption) from concrete were investigated using two 53-L environmental chambers connected in series with a field-collected caulk in the source chamber serving as a stable source of PCBs and building materials in the test chamber. During the tests, the PCB concentrations in the outlet air of the test chamber were monitored and the building materials were removed from the test chamber at different times to determine their PCB content. Among the materials tested, a petroleum-based paint, a latex paint, and a certain type of carpet were among the strongest sinks. Solvent-free epoxy coating, certain types of flooring materials, and brick were among the weakest sinks. For a given sink material, PCB congeners with lower vapor pressures were sorbed in larger quantities. Rough estimates of the partition and diffusion coefficients were obtained by applying a sink model to the data acquired from the chamber studies. A desorption test with the concrete panels showed that re-emission is a slow process, suggesting that PCB sinks, e.g. concrete, can release PCBs into the air for a prolonged period of time (years or decades). This study could fill some of the data gaps associated with the characterization of PCB sinks in contaminated buildings. This paper summarizes the laboratory research results for PCB transport from primary sources to PCB sinks, includ

  2. Chamber study of polychlorinated biphenyl {PCB} emissions ...

    EPA Pesticide Factsheets

    The sorption of airborne polychlorinated biphenyls (PCBs) by twenty building materials and their subsequent re-emission (desorption) from concrete were investigated using two 53-L environmental chambers connected in series with a field-collected caulk in the source chamber serving as a stable source of PCBs and building materials in the test chamber. During the tests, the PCB concentrations in the outlet air of the test chamber were monitored and the building materials were removed from the test chamber at different times to determine their PCB content. Among the materials tested, a petroleum-based paint, a latex paint, and a certain type of carpet were among the strongest sinks. Solvent-free epoxy coating, certain types of flooring materials, and brick were among the weakest sinks. For a given sink material, PCB congeners with lower vapor pressures were sorbed in larger quantities. Rough estimates of the partition and diffusion coefficients were obtained by applying a sink model to the data acquired from the chamber studies. A desorption test with the concrete panels showed that re-emission is a slow process, suggesting that PCB sinks, e.g. concrete, can release PCBs into the air for a prolonged period of time (years or decades). This study could fill some of the data gaps associated with the characterization of PCB sinks in contaminated buildings. This paper summarizes the laboratory research results for PCB transport from primary sources to PCB sinks, includ

  3. Photoacoustic spectroscopy study of Blepharocalyx salicifolius (Kunt) O. Berg

    NASA Astrophysics Data System (ADS)

    Rodriguez, A. F. R.; Jacobson, T. K. B.; Moraes, J. S. F.; Faria, F. S. E. D. V.; Cunha, R. M.; Santos, J. G.; Oliveira, A. C.; Azevedo, R. B.; Morales, M. A.; Morais, P. C.

    Photoacoustic spectroscopy (PAS) has revolutionized the fields of biological, environmental, and agricultural sciences. It is a very simple, sensitive, and non-destructive technique that allows the determination of optical properties of bio-samples. The in vivo chlorophylls of the leaf have a recorded maximum absorption peak at 675 nm as against 665 nm of the in vitro chlorophylls. The intensity of purple pigmentation in leaves of Blepharocalyx salicifolius (Kunt) O. Berg, is inversely correlated to the soil moisture levels, leaf water content and leaf water potentials. The applicability of PAS to biological samples was discussed. It allows the validation of existing emission models which are important for atmospheric process. A portable device for photoacoustic spectroscopy of plants and other photosynthetic tissues, cells and organelles is provided. Further, there is provided a method to measure photosynthesis of such tissues, cells and organelles.

  4. Evaluation of cross-sections for particle induced gamma-ray emission (PIGE) spectroscopy

    NASA Astrophysics Data System (ADS)

    Gurbich, A. F.

    2014-07-01

    The extension of the cross-section evaluation procedure to PIGE data was investigated and the first results are reported. Two different cases were studied: the gamma emission accompanying inelastic scattering of protons, and the (p,γ)-reaction. The corresponding theoretical calculations were performed in the framework of R-matrix and DWBA for the (p,p‧γ) reaction on 23Na, and using statistical model for the proton radiative capture by 52Cr. The possibility of achieving a close fit to the experimental data is demonstrated.

  5. 1,1-dimethylhydrazine as a high purity nitrogen source for MOVPE-water reduction and quantification using nuclear magnetic resonance, gas chromatography-atomic emission detection spectroscopy and cryogenic-mass spectroscopy analytical techniques

    SciTech Connect

    Odedra, R.; Smith, L.M.; Rushworth, S.A.

    2000-01-01

    Hydrazine derivatives are attractive low temperature nitrogen sources for use in MOVPE due to their low thermal stability. However their purification and subsequent analysis has not previously been investigated in depth for this application. A detailed study on 1,1-dimethylhydrazine {l{underscore}brace}(CH{sub 3}){sub 2}N-NH{sub 2}{r{underscore}brace} purified by eight different methods and the subsequent quantitative measurements of water present in the samples obtained is reported here. A correlation between {sup 1}H nuclear magnetic resonance spectroscopy (NMR), gas chromatography-atomic emission detection (GC-AED) and cryogenic mass spectroscopy (Cryogenic-MS) has been performed. All three analysis techniques can be used to measure water in the samples and with the best purification the water content can be lowered well below 100 ppm. The high purity of this material has been demonstrated by growth results and the state-of-the-art performance of laser diodes.

  6. Interfacial Electron Transfer and Transient Photoconductivity Studied with Terahertz Spectroscopy

    NASA Astrophysics Data System (ADS)

    Milot, Rebecca Lee

    Terahertz spectroscopy is distinguished from other far infrared and millimeter wave spectroscopies by its inherent phase sensitivity and sub-picosecond time resolution making it a versatile technique to study a wide range of physical phenomena. As THz spectroscopy is still a relatively new field, many aspects of THz generation mechanisms have not been fully examined. Using terahertz emission spectroscopy (TES), THz emission from ZnTe(110) was analyzed and found to be limited by two-photon absorption and free-carrier generation at high excitation fluences. Due to concerns about the continued use of fossil fuels, solar energy has been widely investigated as a promising source of renewable energy. Dye-sensitized solar cells (DSSCs) have been developed as a low-cost alternative to conventional photovoltaic solar cells. To solve the issues of the intermittency and inefficient transport associated with solar energy, researchers are attempting to adapt DSSCs for water oxidation and chemical fuel production. Both device designs incorporate sensitizer molecules covalently bound to metal oxide nanoparticles. The sensitizer, which is comprised of a chromophore and anchoring group, absorbs light and transfers an electron from its excited state to the conduction band of the metal oxide, producing an electric current. Using time-resolved THz spectroscopy (TRTS), an optical pump/THz probe technique, the efficiency and dynamics of electron injection from sensitizers to metal oxides was evaluated as a function of the chromophore, its anchoring group, and the metal oxide identity. Experiments for studying fully functioning DSSCs and water oxidation devices are also described. Bio-inspired pentafluorophenyl porphyrin chromophores have been designed and synthesized for use in photoelectrochemical water oxidation cells. Influences on the efficiency and dynamics of electron injection from the chromophores into TiO2 and SnO2 nanoparticles due to changes in both the central substituent to

  7. Plasma emission spectroscopy for operating and developing the Spallation Neutron Source (SNS) H{sup −} ion sources

    SciTech Connect

    Han, B. X. Welton, R. F.; Murray, S. N.; Pennisi, T. R.; Santana, M.; Stockli, M. P.

    2014-02-15

    A RF-driven, Cs-enhanced H{sup −} ion source feeds the SNS accelerator with a high current (typically >50 mA), ∼1.0 ms pulsed beam at 60 Hz. To achieve the persistent high current beam for several weeks long service cycles, each newly installed ion source undergoes a rigorous conditioning and cesiation processes. Plasma conditioning outgases the system and sputter-cleans the ion conversion surfaces. A cesiation process immediately following the plasma conditioning releases Cs to provide coverage on the ion conversion surfaces. The effectiveness of the ion source conditioning and cesiation is monitored with plasma emission spectroscopy using a high-sensitivity optical spectrometer. Plasma emission spectroscopy is also used to provide a means for diagnosing and confirming a failure of the insulating coating of the ion source RF antenna which is immersed in the plasma. Emissions of composition elements of the antenna coating material, Na emission being the most significant, drastically elevate to signal a failure when it happens. Plasma spectra of the developmental ion source with an AlN (aluminum nitrite) chamber and an external RF antenna are also briefly discussed.

  8. Coal devolatilization and char combustion study using FTIR spectroscopy

    SciTech Connect

    Raines, T.S.; Brown, R.C.

    1995-12-31

    The goal of this research is to characterize coals during the normal operation of an industrial-scale circulating fluidized bed (CFB) boiler. The method determines coal properties based on the analysis of transient CO and CO{sub 2} emissions from the boiler. Fourier Transform Infrared (FTIR) spectroscopy is used to qualitatively and quantitatively analyze the gaseous products of combustion. The method is non-intrusive and is performed under realistic combustion conditions. Preliminary data suggest that coal devolatilization is complete before char combustion commences in a circulating fluidized bed boiler.

  9. The relationship between gasoline composition and vehicle hydrocarbon emissions: a review of current studies and future research needs.

    PubMed Central

    Schuetzle, D; Siegl, W O; Jensen, T E; Dearth, M A; Kaiser, E W; Gorse, R; Kreucher, W; Kulik, E

    1994-01-01

    The purpose of this paper is to review current studies concerning the relationship of fuel composition to vehicle engine-out and tail-pipe emissions and to outline future research needed in this area. A number of recent combustion experiments and vehicle studies demonstrated that reformulated gasoline can reduce vehicle engine-out, tail-pipe, running-loss, and evaporative emissions. Some of these studies were extended to understand the fundamental relationships between fuel composition and emissions. To further establish these relationships, it was necessary to develop advanced analytical methods for the qualitative and quantitative analysis of hydrocarbons in fuels and vehicle emissions. The development of real-time techniques such as Fourier transform infrared spectroscopy, laser diode spectroscopy, and atmospheric pressure ionization mass spectrometry were useful in studying the transient behavior of exhaust emissions under various engine operating conditions. Laboratory studies using specific fuels and fuel blends were carried out using pulse flame combustors, single- and multicylinder engines, and vehicle fleets. Chemometric statistical methods were used to analyze the large volumes of emissions data generated from these studies. Models were developed that were able to accurately predict tail-pipe emissions from fuel chemical and physical compositional data. Some of the primary fuel precursors for benzene, 1,3-butadiene, formaldehyde, acetaldehyde and C2-C4 alkene emissions are described. These studies demonstrated that there is a strong relationship between gasoline composition and tail-pipe emissions. PMID:7529705

  10. Diffusing Wave Spectroscopy Used to Study Foams

    NASA Technical Reports Server (NTRS)

    Zimmerli, Gregory A.; Durian, Douglas J.

    2000-01-01

    The white appearance of familiar objects such as clouds, snow, milk, or foam is due to the random scattering of light by the sample. As we all know, pure water is clear and easily passes a beam of light. However, tiny water droplets, such as those in a cloud, scatter light because the air and water droplet have different indexes of refraction. When many droplets, or scattering sites, are present, the incident light is scattered in random directions and the sample takes on a milky white appearance. In a glass of milk, the scattering is due to small colloidal particles. The white appearance of shaving cream, or foam, is due to the scattering of light at the water-bubble interface. Diffusing wave spectroscopy (DWS) is a laser light-scattering technique used to noninvasively probe the particle dynamics in systems that strongly scatter light. The technique takes advantage of the diffuse nature of light, which is reflected or transmitted from samples such as foams, dense colloidal suspensions (such as paint and milk), emulsions, liquid crystals, sandpiles, and even biological tissues.

  11. Feasibility study for positron emission mammography.

    PubMed

    Thompson, C J; Murthy, K; Weinberg, I N; Mako, F

    1994-04-01

    A feasibility study is presented for a small, low-cost, dedicated device for positron emission mammography. Two detector arrays above and below the breast would be placed in a conventional mammography unit. These detectors are sensitive to positron annihilation radiation, and are connected to a coincidence circuit and a multiplane image memory. Images of the distribution of positron-emitting isotope are obtained in real time by incrementing the memory location at the intersection of each line of response. Monte Carlo simulations of a breast phantom are compared with actual scans of this phantom in a conventional PET scanner. The simulations and experimental data are used to predict the performance of the proposed system. Spatial resolution experiments using very narrow bismuth germanate BGO crystals suggest that spatial resolutions of about 2 mm should be possible. The efficiency of the proposed device is about ten times that of a conventional brain scanner. The scatter fraction is greater, but the scattered radiation has a very flat distribution. By designing the device to fit in an existing mammography unit, conventional mammograms can be taken after the injection of the radio-pharmaceutical allowing exact registration of the emission and conventional mammographic images.

  12. Micro-Raman Spectroscopy to Complement Proton-Induced X-Ray Emission in the Analysis of Atmospheric Aerosols

    NASA Astrophysics Data System (ADS)

    Safiq, Alexandrea; Ali, Salina; Nadarski, Benjamin; Smith, Jeremy; Yoskowitz, Josh; Labrake, Scott; Vineyard, Michael; Union College Team

    2013-10-01

    There is an active research program in the Union College Ion-Beam Analysis Laboratory on proton-induced X-ray emission (PIXE) analysis of atmospheric aerosols. PIXE is a powerful tool for the study of airborne pollution because it provides information on a broad range of elements simultaneously, has low detection limits, is nondestructive, does not require large samples, and the analysis can be performed in a short amount of time. However, PIXE provides only elemental information. We are investigating the use of Micro-Raman spectroscopy (MRS) to complement PIXE analysis of aerosol samples by providing chemical information. In MRS, laser light is inelastically scattered from a sample and the vibrational spectrum of the scattered light is used to identify molecules and their functional groups. We are focusing on aerosol samples collected in the Adirondack Mountains that have considerable concentrations of sulfur that may contribute to acid rain. The MRS spectra collected on aerosol samples are being compared with a library of standards to try to determine the molecular structures in which the sulfur is bound. We will describe the analysis and present preliminary results. Union College Undergraduate Research Program.

  13. Positron emission tomography of fluorine-18-deoxyglucose and image-guided phosphorus-31 magnetic resonance spectroscopy in brain tumors

    SciTech Connect

    Heiss, W.D.; Heindel, W.; Herholz, K.; Rudolf, J.; Bunke, J.; Jeske, J.; Friedmann, G. )

    1990-03-01

    Positron emission tomography (PET) of 2(18F)-fluoro-2-deoxy-D-glucose (FDG) and volume-selective phosphorus-31 magnetic resonance spectroscopy (31P-MRS) are methods used to assess the energy metabolism of the brain. Both methods were studied with respect to their contribution to differential diagnosis in 23 patients with various brain tumors. The various neuroectodermal tumors differed with respect to their metabolic rate for glucose (MRGL). Benign and malignant tumors could be better differentiated by using tumor metabolism relative to contralateral brain and by evaluating heterogeneities in tumors. Low-grade gliomas usually showed normal 31P-MR spectra; high-grade gliomas were characterized by reduced and often split phosphodiester peaks and alkaline pH. Meningiomas, which had variable MRGL, typically showed extremely low phosphocreatine levels, reduced phosphodiesters, and alkaline pH. We concluded that FDG-PET and 31P-MRS examine different aspects of tumor metabolism. Therefore, both can contribute independently and complementarily to the differential diagnosis of brain tumors.

  14. High resolution soft x-ray spectroscopy of low Z K-shell emission from laser-produced plasmas

    SciTech Connect

    Dunn, J; Magee, E W; Shepherd, R; Chen, H; Hansen, S B; Moon, S J; Brown, G V; Gu, M; Beiersdorfer, P; Purvis, M A

    2008-05-21

    A large radius, R = 44.3 m, High Resolution Grating Spectrometer (HRGS) with 2400 line/mm variable line spacing has been designed for laser-produced plasma experiments conducted at the Lawrence Livermore National Laboratory Jupiter Laser Facility. The instrument has been run with a low-noise, charge-coupled device detector to record high signal-to-noise spectra in the 10-50 {angstrom} wavelength range. The instrument can be run with a 10-20 {micro}m wide slit to achieve the best spectral resolving power, approaching 1000 and similar to crystal spectrometers at 12-20 {angstrom}, or in slitless operation with a small symmetrical emission source. We describe preliminary spectra emitted from various H-like and He-like low Z ion plasmas heated by 100-500 ps (FWHM), 527 nm wavelength laser pulses. This instrument can be developed as a useful spectroscopy platform relevant to laboratory-based astrophysics as well as high energy density plasma studies.

  15. Optical emission spectroscopy of OH lines in N2 and Ar plasma during the treatments of cotton fabric

    NASA Astrophysics Data System (ADS)

    Skoro, Nikola; Puac, Nevena; Spasic, Kosta; Malovic, Gordana; Gorjanc, Marija; Petrovic, Zoran Lj

    2016-09-01

    Low pressure non-equilibrium plasmas are proven to be irreplaceable tool in material processing. Among other fields their applications in treatments of textiles are still diversifying, but the main role of plasma is activation of the surface of treated sample. After, or during, the treatments these surfaces can be covered with different materials or species (such as microcapsules) that enhance properties of the fabric. In order to investigate mechanisms how active species from plasma interact with the cotton surface, we studied both plasma and surface properties. Bleached cotton samples were treated in low-pressure nitrogen and argon plasma in a chamber with parallel-plate electrodes. The effect of the plasma treatment on the cotton samples was investigated with the colorimetric measurements on dyes absorption by a spectrophotometer. Optical emission spectroscopy was performed by using spectrometer with a sensitive CCD camera. We have recorded the evolution of the maximum of the intensity of OH and N2 second positive band lines. Measurement were done with and without samples in the chamber and comparison between the lines intensity was made. The parameters for optimal plasma treatment conditions were determined. Research supported by the MESTD, projects III41011 and ON171037.

  16. Characterization of low-pressure microwave and radio frequency discharges in oxygen applying optical emission spectroscopy and multipole resonance probe

    NASA Astrophysics Data System (ADS)

    Steves, Simon; Styrnoll, Tim; Mitschker, Felix; Bienholz, Stefan; Nikita, Bibinov; Awakowicz, Peter

    2013-11-01

    Optical emission spectroscopy (OES) and multipole resonance probe (MRP) are adopted to characterize low-pressure microwave (MW) and radio frequency (RF) discharges in oxygen. In this context, both discharges are usually applied for the deposition of permeation barrier SiOx films on plastic foils or the inner surface of plastic bottles. For technological reasons the MW excitation is modulated and a continuous wave (cw) RF bias is used. The RF voltage produces a stationary low-density plasma, whereas the high-density MW discharge is pulsed. For the optimization of deposition process and the quality of the deposited barrier films, plasma conditions are characterized using OES and MRP. To simplify the comparison of applied diagnostics, both MW and RF discharges are studied separately in cw mode. The OES and MRP diagnostic methods complement each other and provide reliable information about electron density and electron temperature. In the MW case, electron density amounts to ne = (1.25 ± 0.26) × 1017 m-3, and kTe to 1.93 ± 0.20 eV, in the RF case ne = (6.8 ± 1.8)×1015 m-3 and kTe = 2.6 ± 0.35 eV. The corresponding gas temperatures are 760±40 K and 440±20 K.

  17. High resolution soft x-ray spectroscopy of low Z K-shell emission from laser-produced plasmas.

    PubMed

    Dunn, J; Magee, E W; Shepherd, R; Chen, H; Hansen, S B; Moon, S J; Brown, G V; Gu, M-F; Beiersdorfer, P; Purvis, M A

    2008-10-01

    A large radius, R=44.3 m, high resolution grating spectrometer (HRGS) with 2400 lines/mm variable line spacing has been designed for laser-produced plasma experiments conducted at the Lawrence Livermore National Laboratory Jupiter Laser Facility. The instrument has been run with a low-noise, charge-coupled device detector to record high signal-to-noise spectra in the 10-50 A wavelength range. The instrument can be run with a 10-20 microm wide slit to achieve the best spectral resolving power, approaching 1000 and similar to crystal spectrometers at 12-20 A, or in slitless operation with a small symmetrical emission source. We describe preliminary spectra emitted from various H-like and He-like low Z ion plasmas heated by 100-500 ps (full width at half maximum), 527 nm wavelength laser pulses. This instrument can be developed as a useful spectroscopy platform relevant to laboratory-based astrophysics as well as high energy density plasma studies.

  18. Characterization of low temperature graphene synthesis in inductively coupled plasma chemical vapor deposition process with optical emission spectroscopy.

    PubMed

    Ma, Yifei; Kim, Daekyoung; Jang, Haegyu; Cho, Sung Min; Chae, Heeyeop

    2014-12-01

    Low-temperature graphene was synthesized at 400 degrees C with inductively coupled plasma chemical vapor deposition (PECVD) process. The effects of plasma power and flow rate of various carbon containing precursors and hydrogen on graphene properties were investigated with optical emission spectroscopy (OES). Various radicals monitored by OES were correlated with graphene film properties such as sheet resistance, I(D)/I(G) ratio of Raman spectra and transparency. C2H2 was used as a main precursor and the increase of plasma power enhanced intensity of carbon (C2) radical OES intensity in plasma, reduced sheet resistance and increased transparency of graphene films. The reduced flow rate of C2H2 decreased sheet resistance and increased transparency of graphene films in the range of this study. H2 addition was found to increase sheet resistance, transparency and attributed to reduction of graphene grain and etching graphene layers. OES analysis showed that C2 radicals contribute to graphite networking and sheet resistance reduction. TEM and AFM were applied to provide credible information that graphene had been successfully grown at low temperature.

  19. Spin states of FeOOH at high pressure using x-ray emission spectroscopy and DFT calculations

    NASA Astrophysics Data System (ADS)

    Mao, W. L.; Gleason, A. E.; Pentcheva, R.; Otte, K.; Suzuki, A.

    2011-12-01

    Electronic spin transitions in alpha-FeOOH (goethite) and high-pressure phase epsilon-FeOOH were monitored using high pressure x-ray emission spectroscopy. A high- to low-spin transition in trivalent iron was found in synthesized epsilon-FeOOH on compression at 56.8 GPa, which returned to high-spin on decompression at 20 GPa. This corroborates density-functional theory (DFT) calculations with an on-site Coulomb repulsion term (GGA+U) predict the transition to occur at 56.6 GPa. Compression of alpha-FeOOH to 60 GPa did not show any high- to low-spin transition consistent with the DFT results. Monitoring the spin states of iron-oxy-hydroxides as a function of pressure gives insight into the relationship between electronic spin transitions and structural transitions - which has previously been studied in other key mantle minerals, including iron-bearing perovskites and ferropericlase. Furthermore, this may help uncover a connection between water content (presence of hydroxyl) in a mineral and Fe3+ spin-transition pressure at mid- to lower-mantle conditions in the Earth.

  20. Photoelectron Spectroscopy of Hexachloroplatinate-Nucleobase Complexes: Nucleobase Excited State Decay Observed via Delayed Electron Emission

    SciTech Connect

    Sen, Ananya; Matthews, Edward M.; Hou, Gao-Lei; Wang, Xue B.; Dessent, Caroline

    2015-11-14

    We report low-temperature photoelectron spectra of isolated gas-phase complexes of the hexachloroplatinate dianion bound to the nucleobases uracil, thymine, cytosine and adenine. The spectra display well-resolved, distinct peaks that are consistent with complexes where the hexachloroplatinate dianion is largely intact. Adiabatic electron detachment energies for the hexachloroplatinate-nucleobase complexes are measured as 2.26-2.36 eV. The magnitudes of the repulsive Coulomb barriers (RCBs) of the complexes are all ~1.7 eV, values that are lower than the RCB of the uncomplexed PtCl6 2- dianion as a result of charge solvation by the nucleobases. In addition to the resolved spectral features, broad featureless bands indicative of delayed electron detachment are observed in the 193 nm photoelectron spectra of the four clusters. The 266 nm spectra of the PtCl6 2-∙thymine and PtCl6 2-∙adenine complexes also display very prominent delayed electron emission bands. These results mirror recent results on the related Pt(CN)4 2-∙nucleobase complexes [Sen et al, J. Phys. Chem. B, 119, 11626, 2015]. The observation of delayed electron emission bands in the PtCl6 2-∙nucleobase spectra obtained in this work, as for the previously studied Pt(CN)4 2-∙nucleobase complexes, is attributed to onephoton excitation of nucleobase-centred excited states that can effectively couple to the electron detachment continuum, producing strong electron detachment. Moreover, the selective, strong excitation of the delayed emission bands in the 266 nm spectra is linked to fundamental differences in the individual nucleobase photophysics at this excitation energy. This strongly supports our previous suggestion that the dianion within these clusters can be viewed as a “dynamic tag” which has the propensity to emit electrons when the attached nucleobase decays over a timescale long enough to allow autodetachment.

  1. Doppler spectroscopy and D-alpha emission diagnostics for the C-2 FRC plasma

    SciTech Connect

    Gupta, Deepak K.; Paganini, E.; Bonelli, L.; Deng, B. H.; Gornostaeva, O.; Hayashi, R.; Knapp, K.; McKenzie, M.; Pousa-Hijos, R.; Primavera, S.; Schroeder, J.; Tuszewski, M.; Balvis, A.; Giammanco, F.; Marsili, P.

    2010-10-15

    Two Doppler spectroscopy diagnostics with complementary capabilities are developed to measure the ion temperatures and velocities of FRC plasmas in the C-2 device. First, the multichord ion doppler diagnostic can simultaneously measure 15 chords of the plasma using an image intensified camera. Second, a single-chord fast-response ion Doppler diagnostic provides much higher faster time response by using a 16-channel photo-multiplier tube array. To study the neutral density of deuterium under different wall and plasma conditions, a highly sensitive eight-channel D-alpha diagnostic has been developed and calibrated for absolute radiance measurements. These spectroscopic diagnostics capabilities, combined with other plasma diagnostics, are helping to understand and improve the field reversed configuration plasmas in the C-2 device.

  2. Doppler spectroscopy and D-alpha emission diagnostics for the C-2 FRC plasma.

    PubMed

    Gupta, Deepak K; Paganini, E; Balvis, A; Bonelli, L; Deng, B H; Giammanco, F; Gornostaeva, O; Hayashi, R; Knapp, K; Marsili, P; McKenzie, M; Pousa-Hijos, R; Primavera, S; Schroeder, J; Tuszewski, M

    2010-10-01

    Two Doppler spectroscopy diagnostics with complementary capabilities are developed to measure the ion temperatures and velocities of FRC plasmas in the C-2 device. First, the multichord ion doppler diagnostic can simultaneously measure 15 chords of the plasma using an image intensified camera. Second, a single-chord fast-response ion Doppler diagnostic provides much higher faster time response by using a 16-channel photo-multiplier tube array. To study the neutral density of deuterium under different wall and plasma conditions, a highly sensitive eight-channel D-alpha diagnostic has been developed and calibrated for absolute radiance measurements. These spectroscopic diagnostics capabilities, combined with other plasma diagnostics, are helping to understand and improve the field reversed configuration plasmas in the C-2 device.

  3. Estimation of vehicular emissions using dynamic emission factors: A case study of Delhi, India

    NASA Astrophysics Data System (ADS)

    Mishra, Dhirendra; Goyal, P.

    2014-12-01

    The estimation of vehicular emissions depends mainly on the values of emission factors, which are used for the development of a comprehensive emission inventory of vehicles. In this study the variations of emission factors as well as the emission rates have been studied in Delhi. The implementation of compressed natural gas (CNG), in the diesel and petrol, public vehicles in the year 2001 has changed the complete air quality scenario of Delhi. The dynamic emission factors of criteria pollutants viz. carbon monoxide (CO), nitrogen oxide (NOx) and particulate matter (PM10) for all types of vehicles have been developed after, which are based on the several factors such as regulated emission limits, number of vehicle deterioration, vehicle increment, vehicle age etc. These emission factors are found to be decreased continuously throughout the study years 2003-2012. The International Vehicle Emissions (IVE) model is used to estimate the emissions of criteria pollutants by utilizing a dataset available from field observations at different traffic intersections in Delhi. Thus the vehicular emissions, based on dynamic emission factors have been estimated for the years 2003-2012, which are found to be comparable with the monitored concentrations at different locations in Delhi. It is noticed that the total emissions of CO, NOx, and PM10 are increased by 45.63%, 68.88% and 17.92%, respectively up to the year 2012 and the emissions of NOx and PM10 are grown continuously with an annual average growth rate of 5.4% and 1.7% respectively.

  4. Assessment of the maturity and biological parameters of compost produced from dairy manure and rice chaff by excitation-emission matrix fluorescence spectroscopy.

    PubMed

    Tian, Wei; Li, Lingzhi; Liu, Fang; Zhang, Zhenhua; Yu, Guanghui; Shen, Qirong; Shen, Biao

    2012-04-01

    The assessment of maturity and biological parameters is important in the composting process. In this study, excitation-emission matrix (EEM) fluorescence spectroscopy was applied to evaluate the maturity and biological parameters of compost produced from the co-composting of dairy and rice chaff. The results from a Pearson correlation analysis between traditional physico-chemical maturity indices and fluorescence regional integration (FRI) parameters showed that among the FRI parameters, P(V,n)/P(III,n) and P(V,n) were suitable for the assessment of compost maturity. Moreover, the FRI parameters could be used to evaluate biological parameters including the germination index (GI) and ribotype evolution which indicate the bacterial community structure and dynamics. P(IV,n) was the most suitable indicator for revealing the community structure and dynamics during the composting process. Fluorescence spectroscopy combined with the FRI analysis could be used as a sensitive and efficient tool for assessing compost maturity and biological parameters.

  5. Infrared heterodyne spectroscopy of astronomical and laboratory sources at 8.5 micron. [absorption line profiles of nitrogen oxide and black body emission from Moon and Mars

    NASA Technical Reports Server (NTRS)

    Mumma, M.; Kostiuk, T.; Cohen, S.; Buhl, D.; Vonthuna, P. C.

    1974-01-01

    The first infrared heterodyne spectrometer using tuneable semiconductor (PbSe) diode lasers has been constructed and was used near 8.5 micron to measure absorption line profiles of N2O in the laboratory and black body emission from the Moon and from Mars. Spectral information was recorded over a 200 MHz bandwidth using an 8-channel filter bank. The resolution was 25 MHz and the minimum detectable (black body) power was 1 x 10 to the minus 16th power watts for 8 minutes of integration. The results demonstrate the usefulness of heterodyne spectroscopy for the study of remote and local sources in the infrared.

  6. IFU Spectroscopy of 10 ETG nuclei: Properties of the circumnuclear gas emission

    NASA Astrophysics Data System (ADS)

    Ricci, T. V.

    2015-09-01

    LINERs are galactic nuclei containing spectra with prominence of low-ionization lines. Several ionization sources are able to produce a LINER-like spectra (e.g. shocks, low-luminosity AGNs, pAGB stars). In this work, we will present an analysis performed on a sample of 10 massive ETGs with distances up to 30 Mpc. This sample was observed with the GMOS-IFU installed on the Gemini-South Telescope. The data cubes of the galaxies have a FOV of 3.5 - 5 arcsec2 and a spatial resolution of about 0.6 -- 1.0 arcsec. After subtracting the stellar component of the galaxies by means of spectral synthesis, we studied the emission lines all over the FOV of the data cubes. In galaxies where an AGN was clearly detected, we found ionized gaseous discs and also a low-velocity extended emission perpendicular to the gas discs. We concluded that only ionizing photons emerging from the AGNs are not enough to photoionize the gaseous discs of the galaxies. On the other hand, it seems to be responsible for the photoionization of the low-velocity extended gas perpendicular to the discs. We propose a scheme where some collimating agent, somehow aligned to the gaseous discs, may be present in some LINER-like AGNs in the local universe.

  7. Inductively coupled plasma -- Atomic emission spectroscopy glove box assembly system at the West Valley Demonstration Project

    SciTech Connect

    Marlow, J.H.; McCarthy, K.M.; Tamul, N.R.

    1999-12-17

    The inductively coupled plasma/atomic emission spectroscopy [ICP/AES (ICP)] system for elemental analyses in support of vitrification processing was first installed in 1986. The initial instrument was a Jobin Yvon (JY) Model JY-70 ICP that consisted of sequential and simultaneous spectrometers for analysis of nonradioactive samples as radioactive surrogates. The JY-70 ICP continued supporting nonradioactive testing during the Functional and Checkout Testing of Systems (FACTS) using the full-scale melter with ``cold'' (nonradioactive) testing campaigns. As a result, the need for another system was identified to allow for the analysis of radioactive samples. The Mass Spec (Spectrometry) Lab was established for the installation of the modified ICP system for handling radioactive samples. The conceptual setup of another ICP was predicated on the use of a hood to allow ease of accessibility of the torch, nebulizer, and spray chamber, and the minimization of air flow paths. However, reconsideration of the radioactive sample dose rate and contamination levels led to the configuration of the glovebox system with a common transfer interface box for the ICP and the inductively coupled plasma-mass spectrometer (ICP-MS) glovebox assemblies. As a result, a simultaneous Model JY-50P ICP with glovebox was installed in 1990 as a first generation ICP glovebox system. This was one of the first ICP glovebox assemblies connected with an ICP-MS glovebox system. Since the economics of processing high-level radioactive waste (HLW) required the availability of an instrument to operate 24 hours a day throughout the year without any downtime, a second generation ICP glovebox assembly was designed, manufactured, and installed in 1995 using a Model JY-46P ICP. These two ICP glovebox systems continue to support vitrification of the HLW into canisters for storage. The ICP systems have been instrumental in monitoring vitrification batch processing. To date, remote sample preparation and

  8. Optical emission spectroscopy characterizations of micro-air plasma used for simulation of cell membrane poration

    NASA Astrophysics Data System (ADS)

    Zerrouki, A.; Motomura, H.; Ikeda, Y.; Jinno, M.; Yousfi, M.

    2016-07-01

    A micro-air corona discharge, which is one of the plasmas successfully used for gene transfection in terms of high transfection and cell viability rates, is characterized by optical emission spectroscopy. This non-equilibrium low temperature plasma is generated from the tip of a pulsed high voltage micro-tube (0.2 mm inner diameter and 0.7 mm for outer diameter) placed 2 mm in front of a petri dish containing deionized water and set on a grounded copper plate. The electron temperature, equal to about 6.75 eV near the electrode tip and decreased down to 3.4 eV near the plate, has been estimated, with an error bar of about 30%, from an interesting approach based on the experimental ratio of the closest nitrogen emission spectra of \\text{N}2+ (FNS) at 391.4 nm and N2(SPS) at 394.3 nm. This is based on one hand on a balance equation between creations and losses of the excited upper levels of these two UV spectra and on the other hand on the electron impact rates of the creation of these upper levels calculated from solution of the multi-term Boltzmann equation. Then using the measured Hα spectrum, electron density n e has been estimated from Stark broadening versus the inter-electrode position with an average error bar of about 50%. n e  ≈  1  ×  1015 cm-3 is near the tip coherent with the usual magnitude of electron density in the streamer head developed near the tip of the corona discharges. Rotational temperatures, estimated from comparison of synthetic and experimental spectra of OH(A  -  X), \\text{N}2+ (FNS) at 391.4 nm, and N2(SPS) at 337 nm are respectively equal to 2350 K, 2000 K and 700 K in the gap space. This clearly underlines a thermal non-equilibrium of the corresponding excited species generated inside the thin streamer filaments. But, due to the high dilution of these species in the background gas, these high rotational temperatures do not affect the mean gas temperature that remains close to 300

  9. Water vapor concentration measurement in singlet oxygen generator by using emission spectroscopy method and absorption at 1392nm

    NASA Astrophysics Data System (ADS)

    Zhao, Weili; Wang, Zengqiang; Fang, Benjie; Li, Qingwei; Jin, Yuqi; Sang, Fengting

    2005-12-01

    By using emission spectroscopy method and absorption at 1392nm, partial water pressure at the exit of a square pipe-array jet-type singlet oxygen generator (SPJSOG) for chemical oxygen-iodine laser (COIL) was measured. The water vapor fraction was calculated from the partial water pressure in the diagnostic cell when we assumed the water vapor fraction in the diagnostic cell is the same as that in the generator. The results from the two methods showed that the water vapor concentration is less than 0.08 in this SPJSOG during normal operation. The water vapor fraction decreases with the increasing of the pressure in the generator and rises with the increasing of buffer gas flow rate and the basic hydrogen peroxide (BHP) temperature in the case of constant chlorine flow rate. Measurements showed that the change of water vapor fraction due to BHP temperature could be ignored during normal operation. It is indicated that the gas flow velocity is the main reason that affects on the water vapor fraction in COIL. It is proved that the emission spectroscopy method is one of the simple and convenient ways to measure the water vapor concentration in singlet oxygen generator (SOG), especially in real time measurements. But absorption spectroscopy method, as a direct measurement, can give the more factual results of the water concentration.

  10. Far-infrared emission line spectroscopy of planetary nebulae from the KAO

    NASA Technical Reports Server (NTRS)

    Dinerstein, Harriet L.

    1994-01-01

    The main focus of the overall project was to study the properties of planetary nebulae using far-infrared emission lines. The observations were conducted with the 'cooled grating spectrometer' or CGS, a moderate-resolution echelle spectrometer designed and built at the Ames Research Center. During the first few years of the program, the emphasis was on emission lines of doubly-ionized oxygen and nitrogen ((O III) 52 and 88 microns, (N III) 57 microns), which arise in the ionized regions of the nebulae. Starting around 1989, our emphasis shifted to observing fine-structure lines of neutral oxygen and singly-ionized carbon ((O I) 63 and 145 microns, (C II) 157 microns), which arise from predominantly neutral material outside the ionized regions. This program was typically assigned one or two observing flights per year. Because these studies required obtaining a substantial sample of objects in order to reach meaningful conclusions, publication of comprehensive papers summarizing all of the results is still pending. However, numerous interim reports based on the airborne results as well as on closely-related supporting observations have been published during the grant period. The bibliographic information for these reports is given in the publications section. An overall summary of the planetary nebula results was presented at the Airborne Astronomy Symposium (20th Anniversary of the KAO) on 8 July 1994; reprints will be provided when available. In parallel with the planetary nebula study, we also observed the (O III) and (N III) lines in several H II regions, and attempted (unsuccessfully) to detect these lines in several old nova remnants and the supernova remnant Cassiopeia A.

  11. Simulating Valence-to-Core X-ray Emission Spectroscopy of Transition Metal Complexes with Time-Dependent Density Functional Theory

    SciTech Connect

    Zhang, Yu; Mukamel, Shaul; Khalil, Munira; Govind, Niranjan

    2015-11-09

    Valence-to-core (VtC) X-ray emission spectroscopy (XES) has emerged as a power- ful technique for the structural characterization of complex organometallic compounds in realistic environments. Since the spectrum represents electronic transitions from the ligand molecular orbitals to the core holes of the metal centers, the approach is more chemically sensitive to the metal-ligand bonding character compared with con- ventional X-ray absorption techniques. In this paper we study how linear-response time-dependent density functional theory (LR-TDDFT) can be harnessed to simulate K-edge VtC X-ray emission spectra reliably. LR-TDDFT allows one to go beyond the single-particle picture that has been extensively used to simulate VtC-XES. We con- sider seven low- and high-spin model complexes involving chromium, manganese and iron transition metal centers. Our results are in good agreement with experiment.

  12. Determination of the electron temperature by optical emission spectroscopy in a 13.56 MHz dusty methane plasma: Influence of the power

    SciTech Connect

    Massereau-Guilbaud, Veronique; Geraud-Grenier, Isabelle; Plain, Andre

    2009-12-01

    Optical emission spectroscopy is applied to the study of a radiofrequency (13.56 MHz) discharge in methane used to obtain hydrogenated carbon films and particles. The methane dissociation allows the creation of species in the plasma bulk as H{sub 2}, H, and CH. The emission lines of these species are studied as a function of time and of incident rf power. The electron temperature is determined from the two line radiance ratio method and the corona balance model using the Balmer lines (H{sub alpha}, H{sub beta}, and H{sub gamma}). The incident rf power enhancement in the range 40-120 W leads to the increase in the emission line intensities as the electron temperature decreases. The temporal variations of CH and hydrogen emission lines, of the dc self-bias voltage, and of the electron temperature are correlated both with the particle behavior and growth in the plasma, and with the coating that grows onto the powered electrode.

  13. Determination of nitrous acid emission factors from a gasoline vehicle using a chassis dynamometer combined with incoherent broadband cavity-enhanced absorption spectroscopy.

    PubMed

    Nakashima, Yoshihiro; Kajii, Yoshizumi

    2017-01-01

    Nitrous acid (HONO) is a well-known source of hydroxyl radicals in the troposphere. Vehicle exhaust is considered to be one of the primary emission sources of HONO. In this study, measurements of HONO in gasoline vehicle exhaust were carried out using a chassis dynamometer combined with incoherent broadband cavity-enhanced absorption spectroscopy. When catalysts were warm, concentrations of HONO were higher than those prior to catalysts warming. Other species, such as CO, and total hydrocarbons (THCs), showed the opposite pattern. There were no correlations evident between HONO and other trace species concentrations immediately after emission. The HONO/NOx ratio, a good proxy for the formation of HONO in atmosphere, ranged from 1.1 to 6.8×10(-3), which was consistent with previous studies. HONO emission factors (EFs) were calculated to be 0.01-3.6mgkg(-1) fuel, which was different from the vehicle's specifications and those reported under different driving cycles. Annual HONO emissions in Japan were estimated using the calculated EFs and other statistical data.

  14. [Application study of IVE vehicle emission model].

    PubMed

    Yao, Zhi-liang; He, Ke-bin; Wang, Qi-dong; Huo, Hong; Liu, Huan; He, Chun-yu; James, Lents

    2006-10-01

    This paper introduced IVE model and presented the method to quantify the main parameters by taking Beijing city as a case. Emissions from different vehicle fleets of Beijing were calculated using IVE model. The results show that emissions factors of buses and trucks were much higher, especially for PM, which were 14 and 44 times those of passenger cars. The daily CO, VOC, NO, and PM emissions of vehicles in Beijing city were 2767.4, 182.5, 353.8 and 7.1 t respectively. Common light duty vehicles were the main emission source of CO and VOC, with the contribution of 42.0% and 34.7% respectively, Trucks were the largest contributor of NO, and PM emissions, with the contribution of 66.3% and 83.0% respectively. The methodology and calculating results of MOBILE6 and IVE model were compared, and advantages of IVE model's application in China were discussed.

  15. NIR emission studies and dielectric properties of Er3+-doped multicomponent tellurite glasses

    NASA Astrophysics Data System (ADS)

    Sajna, M. S.; Thomas, Sunil; Jayakrishnan, C.; Joseph, Cyriac; Biju, P. R.; Unnikrishnan, N. V.

    2016-05-01

    Multicomponent tellurite glasses containing altered concentrations of Er2O3 (ranging from 0 to 1 mol%) were prepared by the standard melt quenching technique. Investigations through energy dispersive X-ray spectroscopy (EDS), Raman scattering spectroscopy, Fourier transform infrared (FTIR) spectroscopy, near-infrared (NIR) emission studies and dielectric measurement techniques were done to probe their compositional, structural, spectroscopic and dielectric characteristics. The broad emission together with the high values of the effective linewidth (~ 63 nm), stimulated emission cross-section (9.67 × 10- 21 cm2) and lifetime (2.56 ms) of 4I13/2 level for 0.5 mol% of Er3+ makes these glasses attractive for broadband amplifiers. From the measured capacitance and dissipation factor, the relative permittivity, dielectric loss and the conductivity were computed; which furnish the dielectric nature of the multicomponent tellurite glasses that depend on the applied frequency. Assuming the ideal Debye behavior as substantiated by Cole-Cole plot, an examination of the real and imaginary parts of impedance was performed. The power-law and Cole-Cole parameters were resolved for all the glass samples. From the assessment of the emission analysis and dielectric properties of the glass samples, it was obvious that the Er3+ ion concentration had played a vital role in tuning the optical and dielectric properties and the 0.5 mol% of Er3+ -doped glass was confirmed as the optimum composition.

  16. NIR emission studies and dielectric properties of Er(3+)-doped multicomponent tellurite glasses.

    PubMed

    Sajna, M S; Thomas, Sunil; Jayakrishnan, C; Joseph, Cyriac; Biju, P R; Unnikrishnan, N V

    2016-05-15

    Multicomponent tellurite glasses containing altered concentrations of Er2O3 (ranging from 0 to 1 mol%) were prepared by the standard melt quenching technique. Investigations through energy dispersive X-ray spectroscopy (EDS), Raman scattering spectroscopy, Fourier transform infrared (FTIR) spectroscopy, near-infrared (NIR) emission studies and dielectric measurement techniques were done to probe their compositional, structural, spectroscopic and dielectric characteristics. The broad emission together with the high values of the effective linewidth (~63 nm), stimulated emission cross-section (9.67 × 10(-21) cm(2)) and lifetime (2.56 ms) of (4)I13/2 level for 0.5 mol% of Er(3+) makes these glasses attractive for broadband amplifiers. From the measured capacitance and dissipation factor, the relative permittivity, dielectric loss and the conductivity were computed; which furnish the dielectric nature of the multicomponent tellurite glasses that depend on the applied frequency. Assuming the ideal Debye behavior as substantiated by Cole-Cole plot, an examination of the real and imaginary parts of impedance was performed. The power-law and Cole-Cole parameters were resolved for all the glass samples. From the assessment of the emission analysis and dielectric properties of the glass samples, it was obvious that the Er(3+) ion concentration had played a vital role in tuning the optical and dielectric properties and the 0.5 mol% of Er(3+) -doped glass was confirmed as the optimum composition.

  17. Ion cyclotron emission studies: Retrospects and prospects

    DOE PAGES

    Gorelenkov, N. N.

    2016-06-05

    Ion cyclotron emission (ICE) studies emerged in part from the papers by A.B. Mikhailovskii published in the 1970s. Among the discussed subjects were electromagnetic compressional Alfv,nic cyclotron instabilities with the linear growth rate similar ~ √(nα/ne) driven by fusion products, -particles which draw a lot of attention to energetic particle physics. The theory of ICE excited by energetic particles was significantly advanced at the end of the 20th century motivated by first DT experiments on TFTR and subsequent JET experimental studies which we highlight. Recently ICE theory was advanced by detailed theoretical and experimental studies on spherical torus (ST) fusionmore » devices where the instability signals previously indistinguishable in high aspect ratio tokamaks due to high toroidal magnetic field became the subjects of experiments. Finally, we discuss prospects of ICE theory applications for future burning plasma (BP) experiments such as those to be conducted in ITER device in France, where neutron and gamma rays escaping the plasma create extremely challenging conditions fusion alpha particle diagnostics.« less

  18. Ion cyclotron emission studies: Retrospects and prospects

    SciTech Connect

    Gorelenkov, N. N.

    2016-06-05

    Ion cyclotron emission (ICE) studies emerged in part from the papers by A.B. Mikhailovskii published in the 1970s. Among the discussed subjects were electromagnetic compressional Alfv,nic cyclotron instabilities with the linear growth rate similar ~ √(nα/ne) driven by fusion products, -particles which draw a lot of attention to energetic particle physics. The theory of ICE excited by energetic particles was significantly advanced at the end of the 20th century motivated by first DT experiments on TFTR and subsequent JET experimental studies which we highlight. Recently ICE theory was advanced by detailed theoretical and experimental studies on spherical torus (ST) fusion devices where the instability signals previously indistinguishable in high aspect ratio tokamaks due to high toroidal magnetic field became the subjects of experiments. Finally, we discuss prospects of ICE theory applications for future burning plasma (BP) experiments such as those to be conducted in ITER device in France, where neutron and gamma rays escaping the plasma create extremely challenging conditions fusion alpha particle diagnostics.

  19. Ion cyclotron emission studies: Retrospects and prospects

    NASA Astrophysics Data System (ADS)

    Gorelenkov, N. N.

    2016-05-01

    Ion cyclotron emission (ICE) studies emerged in part from the papers by A.B. Mikhailovskii published in the 1970s. Among the discussed subjects were electromagnetic compressional Alfvénic cyclotron instabilities with the linear growth rate √ {n_α /n_e } driven by fusion products, -particles which draw a lot of attention to energetic particle physics. The theory of ICE excited by energetic particles was significantly advanced at the end of the 20th century motivated by first DT experiments on TFTR and subsequent JET experimental studies which we highlight. More recently ICE theory was advanced by detailed theoretical and experimental studies on spherical torus (ST) fusion devices where the instability signals previously indistinguishable in high aspect ratio tokamaks due to high toroidal magnetic field became the subjects of experiments. We discuss further prospects of ICE theory applications for future burning plasma (BP) experiments such as those to be conducted in ITER device in France, where neutron and gamma rays escaping the plasma create extremely challenging conditions fusion alpha particle diagnostics.

  20. Luminescence spectroscopy and microscopy applied to study gem materials: a case study of C centre containing diamonds

    NASA Astrophysics Data System (ADS)

    Hainschwang, Thomas; Karampelas, Stefanos; Fritsch, Emmanuel; Notari, Franck

    2013-06-01

    The methods of luminescence spectroscopy and microscopy are widely used for the analysis of gem materials. This paper gives an overview of the most important applications of the analysis of laser and UV excited luminescence by spectroscopy and visually by microscopy with emphasis on diamond, and specifically natural type Ib diamond, little studied so far. Luminescence based techniques are paramount to the gemmological analysis of diamond, in order to determine whether it is natural, treated or synthetic. The great sensitivity of luminescence helps detect some emitting centres that are undetectable by any other analytical method. Hence, especially for diamond, luminescence is an enabling technology, as illustrated by its pioneering use of imagery for the separation of natural and synthetic diamond, and of spectroscopy for the detection of High Pressure-High Temperature treatment. For all other gemstones the applications are at the moment less numerous, but nevertheless they remain highly important. They provide quickly information on the identification of a gem material, and its treatment. Besides the study of broad band emissions caused by various colour centres, the typical PL-causing trace elements (amongst others) are chromium, manganese, uranium and rare earth elements. In pearls the study of broad band luminescence can be useful, and particularly the study of pink to red porphyrin luminescence in pearls from certain species such as Pinctada and Pteria and others can help identify the pearl-producing mollusc, or if a pearl has been dyed or not. Type Ib diamonds are representative of the importance and complexity of the analysis of luminescence by microscopy and spectroscopy. They show a wide range of sometimes very complex emissions that result in luminescence colours from green to yellow to orange or red. These emissions show generally very inhomogeneous distribution. They are caused by a range of defects, however only a few of them are well characterized.

  1. X-Ray Spectroscopy of AS1101 with Chandra, XMM-Newton, and ROSAT: Bandpass Dependence of the Temperature Profile and Soft Excess Emission

    NASA Astrophysics Data System (ADS)

    Bonamente, Massimiliano; Nevalainen, Jukka

    2011-09-01

    We present spatially resolved spectroscopy of the galaxy cluster AS1101, also known as Sèrsic 159-03, with Chandra, XMM-Newton, and ROSAT, and investigate the presence of soft X-ray excess emission above the contribution from the hot intracluster medium. In earlier papers we reported an extremely bright soft excess component that reached 100% of the thermal radiation in the R2 ROSAT band (0.2-0.4 keV), using the H I column density measurement by Dickey and Lockman. In this paper we use the newer Leiden-Argentine-Bonn survey measurements of the H I column density toward AS1101, significantly lower than the previous value, and show that the soft excess emission in AS1101 is now at the level of 10%-20% of the hot gas emission, in line with those of a large sample of clusters analyzed by Bonamente et al. in 2002. The ROSAT soft excess emission is detected regardless of calibration uncertainties between Chandra and XMM-Newton. This new analysis of AS1101 indicates that the 1/4 keV band emission is compatible with the presence of warm-hot intergalactic medium (WHIM) filaments connected to the cluster and extending outward into the intergalactic medium; the temperatures we find in this study are typically lower than those of the WHIM probed in other X-ray studies. We also show that the soft excess emission is compatible with a non-thermal origin as the inverse Compton scattering of relativistic electrons off the cosmic microwave background, with pressure less than 1% of the thermal electrons.

  2. X-RAY SPECTROSCOPY OF AS1101 WITH CHANDRA, XMM-NEWTON, AND ROSAT: BANDPASS DEPENDENCE OF THE TEMPERATURE PROFILE AND SOFT EXCESS EMISSION

    SciTech Connect

    Bonamente, Massimiliano; Nevalainen, Jukka

    2011-09-10

    We present spatially resolved spectroscopy of the galaxy cluster AS1101, also known as Sersic 159-03, with Chandra, XMM-Newton, and ROSAT, and investigate the presence of soft X-ray excess emission above the contribution from the hot intracluster medium. In earlier papers we reported an extremely bright soft excess component that reached 100% of the thermal radiation in the R2 ROSAT band (0.2-0.4 keV), using the H I column density measurement by Dickey and Lockman. In this paper we use the newer Leiden-Argentine-Bonn survey measurements of the H I column density toward AS1101, significantly lower than the previous value, and show that the soft excess emission in AS1101 is now at the level of 10%-20% of the hot gas emission, in line with those of a large sample of clusters analyzed by Bonamente et al. in 2002. The ROSAT soft excess emission is detected regardless of calibration uncertainties between Chandra and XMM-Newton. This new analysis of AS1101 indicates that the 1/4 keV band emission is compatible with the presence of warm-hot intergalactic medium (WHIM) filaments connected to the cluster and extending outward into the intergalactic medium; the temperatures we find in this study are typically lower than those of the WHIM probed in other X-ray studies. We also show that the soft excess emission is compatible with a non-thermal origin as the inverse Compton scattering of relativistic electrons off the cosmic microwave background, with pressure less than 1% of the thermal electrons.

  3. Photoelectron spectroscopy of hexachloroplatinate-nucleobase complexes: Nucleobase excited state decay observed via delayed electron emission

    SciTech Connect

    Sen, Ananya; Matthews, Edward M.; Dessent, Caroline E. H. E-mail: xuebin.wang@pnnl.gov; Hou, Gao-Lei; Wang, Xue-Bin E-mail: xuebin.wang@pnnl.gov

    2015-11-14

    We report low-temperature photoelectron spectra of isolated gas-phase complexes of the hexachloroplatinate dianion bound to the nucleobases uracil, thymine, cytosine, and adenine. The spectra display well-resolved, distinct peaks that are consistent with complexes where the hexachloroplatinate dianion is largely intact. Adiabatic electron detachment energies for the hexachloroplatinate-nucleobase complexes are measured as 2.26-2.36 eV. The magnitudes of the repulsive Coulomb barriers (RCBs) of the complexes are all ∼1.7 eV, values that are lower than the RCB of the uncomplexed PtCl{sub 6}{sup 2−} dianion as a result of charge solvation by the nucleobases. In addition to the resolved spectral features, broad featureless bands indicative of delayed electron detachment are observed in the 193 nm photoelectron spectra of the four clusters. The 266 nm spectra of the PtCl{sub 6}{sup 2−} ⋅ thymine and PtCl{sub 6}{sup 2−} ⋅ adenine complexes also display very prominent delayed electron emission bands. These results mirror recent results on the related Pt(CN){sub 4}{sup 2−} ⋅ nucleobase complexes [A. Sen et al., J. Phys. Chem. B 119, 11626 (2015)]. The observation of delayed electron emission bands in the PtCl{sub 6}{sup 2−} ⋅ nucleobase spectra obtained in this work, as for the previously studied Pt(CN){sub 4}{sup 2−} ⋅ nucleobase complexes, is attributed to one-photon excitation of nucleobase-centred excited states that can effectively couple to the electron detachment continuum, producing strong electron detachment. Moreover, the selective, strong excitation of the delayed emission bands in the 266 nm spectra is linked to fundamental differences in the individual nucleobase photophysics at this excitation energy. This strongly supports our previous suggestion that the dianion within these clusters can be viewed as a “dynamic tag” which has the propensity to emit electrons when the attached nucleobase decays over a time scale long enough to

  4. The potential of passive-remote Fourier transform infrared (FTIR) spectroscopy to detect organic emissions under the Clean Air Act

    SciTech Connect

    Demirgian, J.C.; Hammer, C.L. ); Kroutil, R.T. )

    1992-01-01

    The Clean Air Act of 1990 regulates the emission of 198 air toxics. Currently, there is no existing technology by which a regulatory agency can independently determine if a facility is in compliance. We have successfully tested the ability of passive-remote Fourier transform infrared (FTIR) spectroscopy to detect chemical plumes released in the field. Additional laboratory releases demonstrated that FTIR spectroscopy can detect target analytes in mixtures containing components which have overlapping absorbances. The FTIR spectrometer was able to identify and quantify each component released with an average quantitative error of less than 20% using partial least squares (PLS) analysis and 40% using classical least squares analysis (CLS) when calibration files containing pure components and mixtures were used. Calibration files containing only pure analytes resulted in CLS outperforming PLS analyses.

  5. The potential of passive-remote Fourier transform infrared (FTIR) spectroscopy to detect organic emissions under the Clean Air Act

    SciTech Connect

    Demirgian, J.C.; Hammer, C.L.; Kroutil, R.T.

    1992-07-01

    The Clean Air Act of 1990 regulates the emission of 198 air toxics. Currently, there is no existing technology by which a regulatory agency can independently determine if a facility is in compliance. We have successfully tested the ability of passive-remote Fourier transform infrared (FTIR) spectroscopy to detect chemical plumes released in the field. Additional laboratory releases demonstrated that FTIR spectroscopy can detect target analytes in mixtures containing components which have overlapping absorbances. The FTIR spectrometer was able to identify and quantify each component released with an average quantitative error of less than 20% using partial least squares (PLS) analysis and 40% using classical least squares analysis (CLS) when calibration files containing pure components and mixtures were used. Calibration files containing only pure analytes resulted in CLS outperforming PLS analyses.

  6. Measuring reactive nitrogen emissions from point sources using visible spectroscopy from aircraft.

    PubMed

    Melamed, M L; Solomon, S; Daniel, J S; Langford, A O; Portmann, R W; Ryerson, T B; Nicks, D K; McKeen, S A

    2003-02-01

    Accurate measurements of nitrogen dioxide (NO2), a key trace gas in the formation and destruction of tropospheric ozone, are important in studies of urban pollution. Nitrogen dioxide column abundances were measured during the Texas Air Quality Study 2000 using visible absorption spectroscopy from an aircraft. The method allows for quantification of the integrated total number of nitrogen dioxide molecules in the polluted atmosphere and is hence a useful tool for measuring plumes of this key trace gas. Further, we show how such remote-sensing observations can be used to obtain information on the fluxes of nitrogen dioxide into the atmosphere with unique flexibility in terms of aircraft altitude, and the height and extent of mixing of the boundary layer. Observations of nitrogen dioxide plumes downwind of power plants were used to estimate the flux of nitrogen oxide emitted from several power plants in the Houston and Dallas metropolitan areas and in North Carolina. Measurements taken over the city of Houston were also employed to infer the total flux from the city as a whole.

  7. Measurements @ Sub-Mm Spectroscopy Laboratory of Bologna: Rotational Spectroscopy Applied to Atmospheric Studies

    NASA Astrophysics Data System (ADS)

    Puzzarini, Cristina

    2016-06-01

    The physico-chemistry of the Earth's atmosphere has been one of the main subjects of studies over last years. In particular, the composition of the atmosphere is indeed very important to understand chemical processes linked to depletion of stratospheric ozone and greenhouse effect. The vertical concentration profiles of atmospheric gases can be provided by remote sensing measurements, but they require the accurate knowledge of the parameters involved: line positions, transition intensities, pressure-broadened half-widths, pressure-induced frequency shifts and their temperature dependence. In particular, the collisional broadening parameters have a crucial influence on the accuracy of spectra calculations and on reduction of remote sensing data. Rotational spectroscopy, thanks to its intrinsic high resolution, is a powerful tool for providing most of the information mentioned above: accurate or even very accurate rotational transition frequencies, accurate spectroscopic as well as hyperfine parameters, accurate pressure-broadening coefficients and their temperature dependence. With respect to collisional phenomena and line shape analysis studies, by applying the source frequency modulation technique it has been found that rotational spectroscopy may provide very good results: not only this technique does not produce uncontrollable instrumental distortions or broadenings, but also, having an high sensitivity, it is particularly suitable for this kind of investigations. A number of examples will be presented to illustrate the work carried out at the Laboratory of Millimeter/submillimeter-wave Spectroscopy of Bologna in the field of atmospheric studies.

  8. Analytical study of spacecraft deposition contamination by internal reflection spectroscopy

    NASA Technical Reports Server (NTRS)

    Mookherji, T.

    1972-01-01

    Infrared absorption spectra of ten individual contaminant materials and four binary mixtures of these have been studied using the internal reflection spectroscopy technique. The effect of ultraviolet radiation on these contaminants has also been studied. It has been observed that all siloxanes, silanes, and esters are drastically affected by ultraviolet irradiation. In most cases polymerization and tar formation results.

  9. The nature of extreme emission line galaxies at z = 1-2: kinematics and metallicities from near-infrared spectroscopy

    SciTech Connect

    Maseda, Michael V.; Van der Wel, Arjen; Rix, Hans-Walter; Da Cunha, Elisabete; Meidt, Sharon E.; Pacifici, Camilla; Momcheva, Ivelina; Van Dokkum, Pieter; Nelson, Erica J.; Brammer, Gabriel B.; Ferguson, Henry C.; Koekemoer, Anton M.; Franx, Marijn; Fumagalli, Mattia; Bell, Eric F.; Förster-Schreiber, Natascha M.; Koo, David C.; Marchesini, Danilo; Patel, Shannon G.; and others

    2014-08-10

    We present near-infrared spectroscopy of a sample of 22 Extreme Emission Line Galaxies at redshifts 1.3 < z < 2.3, confirming that these are low-mass (M{sub *} = 10{sup 8}-10{sup 9} M{sub ☉}) galaxies undergoing intense starburst episodes (M{sub *}/SFR ∼ 10-100 Myr). The sample is selected by [O III] or Hα emission line flux and equivalent width using near-infrared grism spectroscopy from the 3D-HST survey. High-resolution NIR spectroscopy is obtained with LBT/LUCI and VLT/X-SHOOTER. The [O III]/Hβ line ratio is high (≳ 5) and [N II]/Hα is always significantly below unity, which suggests a low gas-phase metallicity. We are able to determine gas-phase metallicities for seven of our objects using various strong-line methods, with values in the range 0.05-0.30 Z{sub ☉} and with a median of 0.15 Z{sub ☉}; for three of these objects we detect [O III] λ4363, which allows for a direct constraint on the metallicity. The velocity dispersion, as measured from the nebular emission lines, is typically ∼50 km s{sup –1}. Combined with the observed star-forming activity, the Jeans and Toomre stability criteria imply that the gas fraction must be large (f{sub gas} ≳ 2/3), consistent with the difference between our dynamical and stellar mass estimates. The implied gas depletion timescale (several hundred Myr) is substantially longer than the inferred mass-weighted ages (∼50 Myr), which further supports the emerging picture that most stars in low-mass galaxies form in short, intense bursts of star formation.

  10. Vibrational energy dynamics of water studied with ultrafast Stokes and anti-Stokes Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Wang, Zhaohui; Pang, Yoonsoo; Dlott, Dana D.

    2004-10-01

    The transient Stokes Raman spectroscopy method is introduced to study the dynamics of OH-stretching vibrations in water excited by ultrashort infrared pulses. The combination of Stokes and anti-Stokes Raman probing allows the the absorption and emission contributions to be measured separately. Experiments with 3400 cm -1 pumping of OH-stretching of HOD solute in D 2O solvent are reported. The Stokes Raman method is used to study the delay between the excited-state decay and the ground-state recovery, the vibrational Stokes shift, and the generation of weakened hydrogen bonding due to heat released by vibrational relaxation.

  11. OPEN PATH TUNABLE DIODE LASER ABSORPTION SPECTROSCOPY FOR ACQUISITION OF FUGITIVE EMISSION FLUX DATA

    EPA Science Inventory

    Air pollutant emission from unconfined sources is an increasingly important environmental issue. The U.S. EPA has developed a gorund-based optical remote sensing method that enables direct measurement of fugitive emission flux from large area sources. Open-path Fourier transfor...

  12. Fluorescence excitation-emission matrix (EEM) spectroscopy and cavity ring-down (CRD) absorption spectroscopy of oil-contaminated jet fuel using fiber-optic probes.

    PubMed

    Omrani, Hengameh; Barnes, Jack A; Dudelzak, Alexander E; Loock, Hans-Peter; Waechter, Helen

    2012-06-21

    Excitation emission matrix (EEM) and cavity ring-down (CRD) spectral signatures have been used to detect and quantitatively assess contamination of jet fuels with aero-turbine lubricating oil. The EEM spectrometer has been fiber-coupled to permit in situ measurements of jet turbine oil contamination of jet fuel. Parallel Factor (PARAFAC) analysis as well as Principal Component Analysis and Regression (PCA/PCR) were used to quantify oil contamination in a range from the limit of detection (10 ppm) to 1000 ppm. Fiber-loop cavity ring-down spectroscopy using a pulsed 355 nm laser was used to quantify the oil contamination in the range of 400 ppm to 100,000 ppm. Both methods in combination therefore permit the detection of oil contamination with a linear dynamic range of about 10,000.

  13. Development of advanced electrochemical emission spectroscopy for monitoring corrosion in simulated DOE liquid waste. 1998 annual progress report

    SciTech Connect

    MacDonald, D.D.

    1998-06-01

    'Objective of this project is to develop and use Electrochemical Emission Spectroscopy (EES) and other electrochemical techniques as in situ tools for exploring corrosion mechanisms of iron and carbon steel in highly alkaline solutions and for continuously monitoring corrosion on structural materials in DOE liquid waste storage system. In particular, the author will explore the fundamental aspects of the passive behavior of pure iron since breakdown of passivity leads to localized corrosion. This report summarizes work after 1 year of a 3 year project.'

  14. Emission enhancement of underwater collinear dual-pulse laser-induced breakdown spectroscopy with the second pulse defocused

    NASA Astrophysics Data System (ADS)

    Xue, Boyang; Li, Nan; Lu, Yuan; Li, Yuandong; Zheng, Ronger

    2017-03-01

    Axial focusing arrangement effects on collinear dual-pulse laser-induced breakdown spectroscopy (DP-LIBS) in a bulk solution were investigated by spectra and fast images. By properly defocusing the second laser pulse beyond the first laser formed bubble (LFB), brighter and larger plasmas could be produced due to higher breakdown efficiency and higher expansion efficiency. It is attributed to a distinct mechanism of underwater DP-LIBS that the plasma mostly forms at the bubble-water interface and then expands into the gaseous LFB. The results show that optimization of the axial focusing arrangement in underwater collinear DP-LIBS enables significant emission enhancements with relatively low laser energies.

  15. Remote sensing of temperature and concentration profiles of a gas jet by coupling infrared emission spectroscopy and LIDAR for characterization of aircraft engine exhaust

    NASA Astrophysics Data System (ADS)

    Offret, J.-P.; Lebedinsky, J.; Navello, L.; Pina, V.; Serio, B.; Bailly, Y.; Hervé, P.

    2015-05-01

    Temperature data play an important role in the combustion chamber since it determines both the efficiency and the rate of pollutants emission of engines. Air pollution problem concerns the emissions of gases such as CO, CO2, NO, NO2, SO2 and also aerosols, soot and volatile organic compounds. Flame combustion occurs in hostile environments where temperature and concentration profiles are often not easy to measure. In this study, a temperature and CO2 concentration profiles optical measurement method, suitable for combustion analysis, is discussed and presented. The proposed optical metrology method presents numerous advantages when compared to intrusive methods. The experimental setup comprises a passive radiative emission measurement method combined with an active laser-measurement method. The passive method is based on the use of gas emission spectroscopy. The experimental spectrometer device is coupled with an active method. The active method is used to investigate and correct complex flame profiles. This method similar to a LIDAR (Light Detection And Ranging) device is based on the measurement of Rayleigh scattering of a short laser pulse recorded using a high-speed streak camera. The whole experimental system of this new method is presented. Results obtained on a small-scale turbojet are shown and discussed in order to illustrate the potentials deliver by the sophisticated method. Both temperature and concentration profiles of the gas jet are presented and discussed.

  16. Optical emission spectroscopy of 50 Hz pulsed dc nitrogen-hydrogen plasma in the presence of active screen cage

    NASA Astrophysics Data System (ADS)

    Saeed, A.; Abrar, M.; Khan, A. W.; Jan, F.; Khan, B. S.; Shah, H. U.; Zaka-ul-Islam, M.; Zakaullah, M.

    2016-05-01

    The N2-H2 plasma gas mixture, generated in a 50 Hz pulsed dc discharge system with active screen cage, is characterized by optical emission spectroscopy (OES), as a function of gas pressure, the fractions of hydrogen and current density. The N2 dissociation degree and N atomic density was measured with actinometery where argon gas is used as actinometer. It was shown that the increase in hydrogen fraction enhances the dissociation of N2, until the maximum of 40%. The excitation temperature is determined from Ar-I emission line intensities by using the simple Boltzmann plot method. The dissociation fraction and excitation temperature is found to increase with hydrogen mixing in nitrogen plasma.

  17. Low temperature-grown GaAs carrier lifetime evaluation by double optical pump terahertz time-domain emission spectroscopy.

    PubMed

    Mag-Usara, Valynn Katrine; Funkner, Stefan; Niehues, Gudrun; Prieto, Elizabeth Ann; Balgos, Maria Herminia; Somintac, Armando; Estacio, Elmer; Salvador, Arnel; Yamamoto, Kohji; Hase, Muneaki; Tani, Masahiko

    2016-11-14

    We present the use of a "double optical pump" technique in terahertz time-domain emission spectroscopy as an alternative method to investigate the lifetime of photo-excited carriers in semiconductors. Compared to the commonly employed optical pump-probe transient photo-reflectance, this non-contact and room temperature characterization technique allows relative ease in achieving optical alignment. The technique was implemented to evaluate the carrier lifetime in low temperature-grown gallium arsenide (LT-GaAs). The carrier lifetime values deduced from "double optical pump" THz emission decay curves show good agreement with data obtained from standard transient photo-reflectance measurements on the same LT-GaAs samples grown at 250 °C and 310 °C.

  18. Radio imaging spectroscopy of synchrotron emission associated with a CME on the 14th of August 2010

    NASA Astrophysics Data System (ADS)

    Bain, Hazel; Krucker, S.; Saint-Hilaire, P.; Raftery, C.

    2013-07-01

    We present Nancay Radioheliograph observations of a moving type IV solar radio burst which occurred in association with a CME on the 14th of August 2010. The event was well observed at extreme ultraviolet wavelengths by the Atmospheric Imaging Assembly onboard the Solar Dynamics Observatory, the SWAP instrument onboard Proba2 and by the LASCO white light coronograph. The burst emission was found to be cospatial with the core of the CME. Using radio imaging spectroscopy we are able to characterize the underlying electron distribution and plasma parameters within the source. Fitted spectra reveal a clear power law component consistent with optically thin synchrotron emission from accelerated electrons trapped in the erupting flux rope. As is often observed in type IV bursts, polarization measurements show the source to be moderately polarized during the peak of the burst, before steadily increasing to around 70% as the brightness temperature of the burst decays.

  19. Addiction Studies with Positron Emission Tomography

    ScienceCinema

    Joanna Fowler

    2016-07-12

    Brookhaven scientist Joanna Fowler describes Positron Emission Technology (PET) research at BNL which for the past 30 years has focused in the integration of basic research in radiotracer chemistry with the tools of neuroscience to develop new scientific

  20. Addiction Studies with Positron Emission Tomography

    SciTech Connect

    Joanna Fowler

    2008-10-13

    Brookhaven scientist Joanna Fowler describes Positron Emission Technology (PET) research at BNL which for the past 30 years has focused in the integration of basic research in radiotracer chemistry with the tools of neuroscience to develop new scientific

  1. Ultra-Low Sulfur Gasoline Emissions Study

    EPA Pesticide Factsheets

    Understanding the effects of gasoline sulfur level on the in-use fleet is important for assessing emissions inventories and impacts of future policy decisions. Test fuels were two non-ethanol gasolines with properties typical of certification fuel.

  2. Investigation of the atomic emission spectroscopy of F atoms and CF2 molecules in CF4 plasma processing

    NASA Astrophysics Data System (ADS)

    Jin, Huiliang; Li, Jie; Tang, Caixue; Deng, Wenhui; Chen, Xianhua

    2016-10-01

    The surface chemistry reaction involved in the processing of Atmospheric Pressure Plasma Jet (APPJ) produced from CF4 precursor has been explored. The atomic emission spectroscopy of F atoms and CF2 molecules was investigated as they contribute to substrate etching and FC film formation during APPJ processing. Optical emission spectroscopy (OES) spectra were acquired for CF4 plasma, relative concentrations of excited state species of F atoms and CF2 molecules were also dependent upon plasma parameters. The densities of F atoms increased dramatically with increasing applied RF power, whereas CF2 molecules decreased monotonically over the same power range, the subsequent electron impacted decomposition of plasma species after CF4 precursor fragmentation. The spectrum of the F atoms and CF2 molecules fallowed the same tendency with the increasing concentration of gas CF4, reaching the maximum at the 20sccm and 15sccm respectively, and then the emission intensity of reactive atoms decreased with more CF4 molecules participating. Addition certain amount O2 into CF4 plasma resulted in promoting CF4 dissociation, O2 can easily react with the dissociation product of CF2 molecules, which inhibit the compound of the F atoms, so with the increasing concentration of O2, the concentration of the CF2 molecules decreased and the emission intensities of F atoms showed the maximum at the O2/CF4 ratio of 20%. These results have led to the development of a scheme that illustrates the mechanisms of surface chemistry reaction and the affection of plasma parameters in CF4 plasma systems with respect to F and CF2 gas-phase species.

  3. Resonance Raman spectroscopy study of protonated porphyrin

    NASA Astrophysics Data System (ADS)

    Gorski, A.; Starukhin, A.; Stavrov, S.; Gawinkowski, S.; Waluk, J.

    2017-02-01

    Resonance Raman microscopy was used to study the resonance Raman scattering of the diacid (diprotonated form) of free-base porphyrin (21H,23H-porphine) in a crystal powder and KBr pellets. Intensive lines in the spectral range between 100 ÷ 1000 cm- 1 have been detected and assigned as spectral manifestation of out-of-plane modes. The Raman spectra were simulated by means of DFT methods and compared with the experimental data. It is evident from experimental and theoretical results that the activation of out-of-plane modes arises from saddle distortion of the porphyrin macrocycle upon formation of its diprotonated form.

  4. Francium Spectroscopy for Weak Interaction Studies

    NASA Astrophysics Data System (ADS)

    Orozco, Luis

    2014-05-01

    Francium, a radioactive element, is the heaviest alkali. Its atomic and nuclear structure makes it an ideal laboratory to study the weak interaction. Laser trapping and cooling in-line with the superconducting LINAC accelerator at Stony Brook opened the precision study of its atomic structure. I will present our proposal and progress towards weak interaction measurements at TRIUMF, the National Canadian Accelerator in Vancouver. These include the commissioning run of the Francium Trapping Facility, hyperfine anomaly measurements on a chain of Fr isotopes, the nuclear anapole moment through parity non-conserving transitions in the ground state hyperfine manifold. These measurements should shed light on the nucleon-nucleon weak interaction. This work is done by the FrPNC collaboration: S. Aubin College of William and Mary, J. A. Behr TRIUMF, R. Collister U. Manitoba, E. Gomez UASLP, G. Gwinner U. Manitoba, M. R. Pearson TRIUMF, L. A. Orozco UMD, M. Tandecki TRIUMF, J. Zhang UMD Supported by NSF and DOE from the USA; TRIUMF, NRC and NSERC from Canada; and CONACYT from Mexico

  5. Study of Turbulence by Photon Correlation Spectroscopy

    DTIC Science & Technology

    1991-10-23

    U NCLASEi F D ED AD-A243 726 ’I October 23. 1991 |I Final Report 6/15/89 - 12/15/91 41. U. PAGE _I’: E .. Pg u ft -_-2_ Study of Turbulence by Photon...ZLI1oU NAuM6( Luo AooBSSS4S S. PIWO oGM ATom + Department of Physics and Astronomy R ++ Department of Mechanical Engineering University of...b(R) d (R)f P(V(R))cos(kV(R))dV(R) 1 + G(t), (1) -. . Al .. .. . . isC -, Ir ,,., _., !AVA I J where b(R) = (2/L)(I - RIL) is the number fraction of

  6. X-ray continuum emission spectroscopy from hot dense matter at Gbar pressures.

    PubMed

    Kraus, D; Döppner, T; Kritcher, A L; Bachmann, B; Chapman, D A; Collins, G W; Glenzer, S H; Hawreliak, J A; Landen, O L; Ma, T; Le Pape, S; Neumayer, P; Swift, D C; Falcone, R W

    2014-11-01

    We have measured the time-resolved x-ray continuum emission spectrum of ∼30 times compressed polystyrene created at stagnation of spherically convergent shock waves within the Gbar fundamental science campaign at the National Ignition Facility. From an exponential emission slope between 7.7 keV and 8.1 keV photon energy and using an emission model which accounts for reabsorption, we infer an average electron temperature of 375 ± 21 eV, which is in good agreement with HYDRA-1D simulations.

  7. X-ray continuum emission spectroscopy from hot dense matter at Gbar pressures

    SciTech Connect

    Kraus, D. Falcone, R. W.; Döppner, T.; Kritcher, A. L.; Bachmann, B.; Collins, G. W.; Hawreliak, J. A.; Landen, O. L.; Ma, T.; Le Pape, S.; Swift, D. C.; Chapman, D. A.; Glenzer, S. H.; Neumayer, P.

    2014-11-15

    We have measured the time-resolved x-ray continuum emission spectrum of ∼30 times compressed polystyrene created at stagnation of spherically convergent shock waves within the Gbar fundamental science campaign at the National Ignition Facility. From an exponential emission slope between 7.7 keV and 8.1 keV photon energy and using an emission model which accounts for reabsorption, we infer an average electron temperature of 375 ± 21 eV, which is in good agreement with HYDRA-1D simulations.

  8. Spectroscopy of Light Emission from a Scanning Tunneling Microscope in Air

    NASA Astrophysics Data System (ADS)

    Péchou, R.; Coratger, R.; Girardin, C.; Ajustron, F.; Beauvillain, J.

    1996-11-01

    Light emission has been detected at the tip-sample junction of a Scanning Tunneling Microscope (S.T.M.) in air on noble metallic surfaces. A spectroscopic study of emitted photons for Au-Au and PtIr-Au tunneling junctions is presented. The general aspect of the spectra depends on the materials used in the junctions; a study of the spectra as a function of tunneling current and surface bias voltage reveals similar and reproducible characteristics. Une émission de lumière a été détectée au niveau de la jonction pointe-surface d'un microscope à effet tunnel dans l'air sur des surfaces de métaux nobles. Une étude spectroscopique des photons émis par des jonctions tunnel Au-Au et PtIr-Au est présentée. L'aspect général des spectres dépend des matériaux utilisés ; une étude en fonction du courant tunnel et de la tension de polarisation de la jonction révéle des caractéristiques similaires et reproductibles.

  9. Optical spectroscopy study of Weyl Semimetal NbP

    NASA Astrophysics Data System (ADS)

    Yang, Jeremy; Jiang, Yuxuan; Dun, Zhiling; Zhou, Haidong; Smirnov, Dmitry; Jiang, Zhigang

    Weyl semimetals have attracted much interest lately because of its unique band structure, where conduction band and valence band touch at discrete points. Here, we report on optical spectroscopy study of Weyl semimetal NbP, seeking evidence for the existence of Weyl fermions. Specifically, using Raman spectroscopy we investigate the anisotropic response of Raman-active phonon modes in NbP and compare with Quantum Espresso simulations. Using magneto-infrared spectroscopy in a high magnetic field up to 17.5T, we observe several Landau level transitions and compare with the theoretical model of three-dimensional massless Dirac/Weyl fermions. By combining our data with low-temperature magneto-transport measurement, the magnetic field dispersion of Landau levels in NbP is obtained.

  10. Lasing dynamics study by femtosecond time-resolved fluorescence non-collinear optical parametric amplification spectroscopy

    NASA Astrophysics Data System (ADS)

    Wei, Dang; Qing, Liao; Peng-Cheng, Mao; Hong-Bing, Fu; Yu-Xiang, Weng

    2016-05-01

    Femtosecond time-resolved fluorescence non-collinear optical parametric amplification spectroscopy (FNOPAS) is a versatile technique with advantages of high sensitivity, broad detection bandwidth, and intrinsic spectrum correction function. These advantages should benefit the study of coherent emission, such as measurement of lasing dynamics. In this letter, the FNOPAS was used to trace the lasing process in Rhodamine 6G (R6G) solution and organic semiconductor nano-wires. High-quality transient emission spectra and lasing dynamic traces were acquired, which demonstrates the applicability of FNOPAS in the study of lasing dynamics. Our work extends the application scope of the FNOPAS technique. Project supported by the National Natural Science Foundation of China (Grant Nos. 20925313 and 21503066), the Innovation Program of Chinese Academy of Sciences (Grant No. KJCX2-YW-W25), the Postdoctoral Project of Hebei University, China, and the Project of Science and Technology Bureau of Baoding City, China (Grant No. 15ZG029).

  11. ZnO Luminescence and scintillation studied via photoexcitation, X-ray excitation, and gamma-induced positron spectroscopy

    NASA Astrophysics Data System (ADS)

    Ji, J.; Colosimo, A. M.; Anwand, W.; Boatner, L. A.; Wagner, A.; Stepanov, P. S.; Trinh, T. T.; Liedke, M. O.; Krause-Rehberg, R.; Cowan, T. E.; Selim, F. A.

    2016-08-01

    The luminescence and scintillation properties of ZnO single crystals were studied by photoluminescence and X-ray-induced luminescence (XRIL) techniques. XRIL allowed a direct comparison to be made between the near-band emission (NBE) and trap emissions providing insight into the carrier recombination efficiency in the ZnO crystals. It also provided bulk luminescence measurements that were not affected by surface states. The origin of a green emission, the dominant trap emission in ZnO, was then investigated by gamma-induced positron spectroscopy (GIPS) - a unique defect spectroscopy method that enables positron lifetime measurements to be made for a sample without contributions from positron annihilation in the source materials. The measurements showed a single positron decay curve with a 175 ps lifetime component that was attributed to Zn vacancies passivated by hydrogen. Both oxygen vacancies and hydrogen-decorated Zn vacancies were suggested to contribute to the green emission. By combining scintillation measurements with XRIL, the fast scintillation in ZnO crystals was found to be strongly correlated with the ratio between the defect luminescence and NBE. This study reports the first application of GIPS to semiconductors, and it reveals the great benefits of the XRIL technique for the study of emission and scintillation properties of materials.

  12. ZnO Luminescence and scintillation studied via photoexcitation, X-ray excitation, and gamma-induced positron spectroscopy

    PubMed Central

    Ji, J.; Colosimo, A. M.; Anwand, W.; Boatner, L. A.; Wagner, A.; Stepanov, P. S.; Trinh, T. T.; Liedke, M. O.; Krause-Rehberg, R.; Cowan, T. E.; Selim, F. A.

    2016-01-01

    The luminescence and scintillation properties of ZnO single crystals were studied by photoluminescence and X-ray-induced luminescence (XRIL) techniques. XRIL allowed a direct comparison to be made between the near-band emission (NBE) and trap emissions providing insight into the carrier recombination efficiency in the ZnO crystals. It also provided bulk luminescence measurements that were not affected by surface states. The origin of a green emission, the dominant trap emission in ZnO, was then investigated by gamma-induced positron spectroscopy (GIPS) - a unique defect spectroscopy method that enables positron lifetime measurements to be made for a sample without contributions from positron annihilation in the source materials. The measurements showed a single positron decay curve with a 175 ps lifetime component that was attributed to Zn vacancies passivated by hydrogen. Both oxygen vacancies and hydrogen-decorated Zn vacancies were suggested to contribute to the green emission. By combining scintillation measurements with XRIL, the fast scintillation in ZnO crystals was found to be strongly correlated with the ratio between the defect luminescence and NBE. This study reports the first application of GIPS to semiconductors, and it reveals the great benefits of the XRIL technique for the study of emission and scintillation properties of materials. PMID:27550235

  13. ZnO Luminescence and scintillation studied via photoexcitation, X-ray excitation, and gamma-induced positron spectroscopy.

    PubMed

    Ji, J; Colosimo, A M; Anwand, W; Boatner, L A; Wagner, A; Stepanov, P S; Trinh, T T; Liedke, M O; Krause-Rehberg, R; Cowan, T E; Selim, F A

    2016-08-23

    The luminescence and scintillation properties of ZnO single crystals were studied by photoluminescence and X-ray-induced luminescence (XRIL) techniques. XRIL allowed a direct comparison to be made between the near-band emission (NBE) and trap emissions providing insight into the carrier recombination efficiency in the ZnO crystals. It also provided bulk luminescence measurements that were not affected by surface states. The origin of a green emission, the dominant trap emission in ZnO, was then investigated by gamma-induced positron spectroscopy (GIPS) - a unique defect spectroscopy method that enables positron lifetime measurements to be made for a sample without contributions from positron annihilation in the source materials. The measurements showed a single positron decay curve with a 175 ps lifetime component that was attributed to Zn vacancies passivated by hydrogen. Both oxygen vacancies and hydrogen-decorated Zn vacancies were suggested to contribute to the green emission. By combining scintillation measurements with XRIL, the fast scintillation in ZnO crystals was found to be strongly correlated with the ratio between the defect luminescence and NBE. This study reports the first application of GIPS to semiconductors, and it reveals the great benefits of the XRIL technique for the study of emission and scintillation properties of materials.

  14. [Study on spectral emissivity of C/C composites].

    PubMed

    Zhu, Bo; Cao, Wei-Wei; Jing, Min; Dong, Xing-Guang; Wang, Cheng-Guo

    2009-11-01

    Different types of C/C composites were prepared by conventional molding, and the changes in normal spectral emissivity of samples were tested. The testing results show that spectral emissivity of C/C composite reinforced by short cut carbon fibers is generally higher than the sample reinforced by carbon cloth in the entire 2500-13000nm wavelength region. The structure of short cut carbon fibers is relatively loose and the number of material particles is less than other samples in unit volume, which increases the penetration depth of electromagnetic waves. This is the reason for higher normal spectral emissivity and better heat radiation property. Meanwhile, the test results of normal spectral emissivity for fiber perform and C/C composite samples show that the spectral emissivity of resin carbon is better than fiber carbon because of the difference in microstructure for the two kinds of carbon materials. Laser Raman spectroscopy was employed to analyze the microstructures of different carbon materials, and the results show that because sp3 and sp2 hybrid states of carbon atoms in resin carbon produced more vibration modes, the resin carbon also has higher normal spectral emissivity and better characteristics of heat radiation.

  15. Social Perception in Infancy: A Near Infrared Spectroscopy Study

    ERIC Educational Resources Information Center

    Lloyd-Fox, Sarah; Blasi, Anna; Volein, Agnes; Everdell, Nick; Elwell, Claire E.; Johnson, Mark H.

    2009-01-01

    The capacity to engage and communicate in a social world is one of the defining characteristics of the human species. While the network of regions that compose the social brain have been the subject of extensive research in adults, there are limited techniques available for monitoring young infants. This study used near infrared spectroscopy to…

  16. Positron annihilation spectroscopy study of materials for reactor vessels

    NASA Astrophysics Data System (ADS)

    Grafutin, V. I.; Prokop'ev, E. P.; Krsjak, V.; Burcl, R.; Hähner, P.; Zeman, A.; Ilyukhina, O. V.; Erak, D.; Mogilevskyi, M. A.; Myasischeva, G. G.; Funtikov, Yu. V.

    2011-02-01

    Steels used in the nuclear industry have been experimentally studied by positron annihilation spectroscopy. Analysis of the experimental results and their comparison with the existing data make it possible to reveal vacancy defects, in particular, those caused by neutron radiation, and to determine their size.

  17. Evidence of satellite valley position in GaN by photoexcited field emission spectroscopy

    NASA Astrophysics Data System (ADS)

    Yilmazoglu, O.; Pavlidis, D.; Hartnagel, H. L.; Evtukh, A.; Litovchenko, V.; Semenenko, N.

    2008-06-01

    GaN field emitter rods with nanometer diameter were fabricated by photoelectrochemical etching on a n+-GaN substrate. Their electron field emission properties were investigated under ultraviolet (UV) illumination. The Fowler-Nordheim plots of the emission current show different slopes for nonilluminated and UV illuminated devices. A model based on the electron emission from valleys having different specific electron affinities is proposed to explain the experimental results. In the absence of illumination, the GaN rods are almost fully depleted and emission takes place only from the lower valley. Upon UV illumination and presence of a high electric field at the emitter tip, the upper valley of the conduction band appears to be occupied by electrons generated at the valence band. The energy difference between the lower and upper valleys was determined to be 1.15eV and is in good agreement with formerly published theoretical and measured values.

  18. Optical Spectroscopy Study of Transparent Non-Carious Human Dentin and Dentin-Enamel Junction

    SciTech Connect

    Marshall, G.W.; Marshall, S.J.; Gallagher, R.R.; Demos, S.

    1999-12-14

    Improving our knowledge of the morphology, composition and properties of the dentin, enamel, and the dentin-enamel junction (DEJ) is vital for the development of improved restorative materials and clinical placement techniques. Most studies of dental tissues have used light microscopy for characterization. In our investigation, the spectroscopic properties of normal and non-carious transparent human root dentin, and the dentin-enamel junction were investigated using emission imaging microscopy, and micro-spectroscopy. Experimental results reveal new information on the structural and biochemical characteristics of these dental tissues.

  19. The Development of Cavity Ringdown Spectroscopy as a Toxic Metal Continuous Emission Monitor

    SciTech Connect

    Dr. Goeroge P. Miller; Dr. Christopher B. Winstead

    2001-12-04

    Innovative program to explore the viability of using Cavity Ringdown Spectroscopy (CRDS) for trace analysis and monitoring of remediation processes for hazardous and radioactive wastes. Cavity ringdown spectroscopy is a measurement of the rate of absorption of a sample within a closed optical cavity rather than the standard measurement of the avsorved signal strength over a given sample path. It is a technique capable of providing ultra-sensitive absorption measurements in hostile environments using commercially available easy-to-use pulsed lasers. The inherent high sensitivity stems from both the long effective sample pathlengths possible and the relaxed constraints on the accuracy of the measurement of the cavity decay time.

  20. Characterization of RF He-N2/Ar mixture plasma via Langmuir probe and optical emission spectroscopy techniques

    NASA Astrophysics Data System (ADS)

    Younus, Maria; Rehman, N. U.; Shafiq, M.; Hussain, S. S.; Zakaullah, M.; Zaka-ul-Islam, M.

    2016-08-01

    A Magnetic Pole Enhanced inductively coupled RF H e - N 2 / A r plasma is characterized using a Langmuir probe and optical emission spectroscopy (OES) techniques. The effect of helium mixing on electron density ( n e ) and temperature ( T e ) , electron energy probability functions (EEPFs), [ N ] atomic density, and N 2 dissociation is investigated. A Langmuir probe and a zero slope method based on trace rare gas-optical emission spectroscopy (TRG-OES) are employed to measure the electron temperature. It is noted that the electron temperature shows an increasing trend for both methods. However, the temperature measured by a zero slope method T e ( Z . S ) approaches the temperature measured by a Langmuir probe; T e ( L . P ) at 56% and above helium concentration in the discharge. "Advance actinometry" is employed to monitor the variation in [ N ] atomic density with helium concentration and gas pressure. It is noted that [ N ] atomic density increases at 56% and above helium in the discharge, which is consistent with the trend of electron temperature and EEPFs. A drastic enhancement in N 2 dissociation fraction D 1 determined by "advance actinometry" is noted at 56% and above helium concentration in the mixture due to modifications in different population and depopulation mechanisms. However, it is also noted that the dissociation fraction D 2 determined by intensity ratio method increases linearly with helium addition.

  1. The London low emission zone baseline study.

    PubMed

    Kelly, Frank; Armstrong, Ben; Atkinson, Richard; Anderson, H Ross; Barratt, Ben; Beevers, Sean; Cook, Derek; Green, Dave; Derwent, Dick; Mudway, Ian; Wilkinson, Paul

    2011-11-01

    On February 4, 2008, the world's largest low emission zone (LEZ) was established. At 2644 km2, the zone encompasses most of Greater London. It restricts the entry of the oldest and most polluting diesel vehicles, including heavy-goods vehicles (haulage trucks), buses and coaches, larger vans, and minibuses. It does not apply to cars or motorcycles. The LEZ scheme will introduce increasingly stringent Euro emissions standards over time. The creation of this zone presented a unique opportunity to estimate the effects of a stepwise reduction in vehicle emissions on air quality and health. Before undertaking such an investigation, robust baseline data were gathered on air quality and the oxidative activity and metal content of particulate matter (PM) from air pollution monitors located in Greater London. In addition, methods were developed for using databases of electronic primary-care records in order to evaluate the zone's health effects. Our study began in 2007, using information about the planned restrictions in an agreed-upon LEZ scenario and year-on-year changes in the vehicle fleet in models to predict air pollution concentrations in London for the years 2005, 2008, and 2010. Based on this detailed emissions and air pollution modeling, the areas in London were then identified that were expected to show the greatest changes in air pollution concentrations and population exposures after the implementation of the LEZ. Using these predictions, the best placement of a pollution monitoring network was determined and the feasibility of evaluating the health effects using electronic primary-care records was assessed. To measure baseline pollutant concentrations before the implementation of the LEZ, a comprehensive monitoring network was established close to major roadways and intersections. Output-difference plots from statistical modeling for 2010 indicated seven key areas likely to experience the greatest change in concentrations of nitrogen dioxide (NO2) (at least 3

  2. Emission polarization study on quartz and calcite.

    NASA Technical Reports Server (NTRS)

    Vincent, R. K.

    1972-01-01

    Calculation of the spectral emission polarization of quartz and calcite polished plates for observation angles of 20 and 70 deg by the substitution of complex index of refraction values for each mineral into Fresnel's equations. The emission polarization is shown to be quite wavelength-dependent, demonstrating that selected narrow or medium-width spectral bands exhibit a significantly higher percentage of polarization than a broad spectral band for these two minerals. Field measurements with a broadband infrared radiometer yield polarizations on the order of 2% for a coarse-grained granite rock and beach sand (both quartz-rich). This implies that a more sensitive detector with a selected medium-width filter may be capable of measuring emission polarization accurately enough to make this parameter useful as a remote sensing tool for discrimination among rocks on the basis of texture.

  3. Time-resolved characterization of a filamentary argon discharge at atmospheric pressure in a capillary using emission and absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Schröter, Sandra; Pothiraja, Ramasamy; Awakowicz, Peter; Bibinov, Nikita; Böke, Marc; Niermann, Benedikt; Winter, Jörg

    2013-11-01

    An argon/nitrogen (0.999/0.001) filamentary pulsed discharge operated at atmospheric pressure in a quartz tube is characterized using voltage-current measurements, microphotography, optical emission spectroscopy (OES) and absorption spectroscopy. Nitrogen is applied as a sensor gas for the purpose of OES diagnostic. The density of argon metastable atoms Ar(3P2) is determined using tunable diode laser absorption spectroscopy (TDLAS). Using a plasma chemical model the measured OES data are applied for the characterization of the plasma conditions. Between intense positive pulses the discharge current oscillates with a damped amplitude. It is established that an electric current flows in this discharge not only through a thin plasma filament that is observed in the discharge image but also through the whole cross section of the quartz tube. A diffuse plasma fills the quartz tube during a time between intense current pulses. Ionization waves are propagating in this plasma between the spike and the grounded area of the tube producing thin plasma channels. The diameter of these channels increases during the pause between the propagation of ionization waves probably because of thermal expansion and diffusion. Inside the channels electron densities of ˜2 × 1013 cm-3, argon metastable densities ˜1014 cm-3 and a reduced electric field about 10 Td are determined.

  4. Determination of major combustion products in aircraft exhausts by FTIR emission spectroscopy

    NASA Astrophysics Data System (ADS)

    Heland, J.; Schäfer, K.

    The results of ground-based FTIR emission measurements of major combustion products such as CO 2, H 2O, CO, NO, and N 2O of in-service aircraft engines are reported and compared to values published in recent literature. About 25% differences in the NO and CO emission indices at several power settings were found for two military bypass engines of the same type. In addition the measured CO emission index of (51.8±4.6) g kg -1 at idle power of a CFM56-3 engine was about 27% lower than the value given by Spicer et al. (1984, 1994)for this engine type and about 27-48% higher than the ICAO data ( ICAO, 1995) for the whole span of CFM56-3 engines. The CO emission index measured at idle power of a CFM56-5C2 engine of AN Airbus A340 was (24±4) g kg -1 and can be compared to the ICAO value of 34 g kg -1. The N 2O mixing ratios measured at a higher power setting of this engine was found to be 4 ppm and is in the range of reported literature values. Since the NO and CO emissions are strongly connected to the combustion process/efficiency and thus to the state of engine maintainance and/or the engine age, it can be concluded that there are significant engine-to-engine (of the same type) and possibly day-to-day variations in the emission characteristics of aero engines which cannot be neglected for the estimation of the overall air-traffic emissions.

  5. Utilization of PARAFAC-Modeled Excitation-Emission Matrix (EEM) Fluorescence Spectroscopy to Identify Biogeochemical Processing of Dissolved Organic Matter in a Northern Peatland.

    PubMed

    Tfaily, Malak M; Corbett, Jane E; Wilson, Rachel; Chanton, Jeffrey P; Glaser, Paul H; Cawley, Kaelin M; Jaffé, Rudolf; Cooper, William T

    2015-01-01

    In this study, we contrast the fluorescent properties of dissolved organic matter (DOM) in fens and bogs in a Northern Minnesota peatland using excitation emission matrix fluorescence spectroscopy with parallel factor analysis (EEM-PARAFAC). EEM-PARAFAC identified four humic-like components and one protein-like component and the dynamics of each were evaluated based on their distribution with depth as well as across sites differing in hydrology and major biological species. The PARAFAC-EEM experiments were supported by dissolved organic carbon measurements (DOC), optical spectroscopy (UV-Vis), and compositional characterization by ultrahigh resolution Fourier transform ion cyclotron resonance mass spectroscopy (FT-ICR MS). The FT-ICR MS data indicate that metabolism in peatlands reduces the molecular weights of individual components of DOM, and oxygen-rich less aromatic molecules are selectively biodegraded. Our data suggest that different hydrologic and biological conditions within the larger peat ecosystem drive molecular changes in DOM, resulting in distinctly different chemical compositions and unique fluorescent fingerprints. PARAFAC modeling of EEM data coupled with ultrahigh resolution FT-ICR MS has the potential to provide significant molecular-based information on DOM composition that will support efforts to better understand the composition, sources, and diagenetic status of DOM from different terrestrial and aquatic systems.

  6. UVES and X-Shooter spectroscopy of the emission line AM CVn systems GP Com and V396 Hya

    NASA Astrophysics Data System (ADS)

    Kupfer, T.; Steeghs, D.; Groot, P. J.; Marsh, T. R.; Nelemans, G.; Roelofs, G. H. A.

    2016-04-01

    We present time-resolved spectroscopy of the AM CVn-type binaries GP Com and V396 Hya obtained with VLT/X-Shooter and VLT/UV-Visual Echelle Spectrograph (UVES). We fully resolve the narrow central components of the dominant helium lines and determine radial velocity semi-amplitudes of Kspike = 11.7 ± 0.3 km s-1 for GP Com and Kspike = 5.8 ± 0.3 km s-1 for V396 Hya. The mean velocities of the narrow central components show variations from line to line. Compared to calculated line profiles that include Stark broadening we are able to explain the displacements, and the appearance of forbidden helium lines, by additional Stark broadening of emission in a helium plasma with an electron density ne ≃ 5 × 1015 cm-3. More than 30 nitrogen and more than 10 neon lines emission lines were detected in both systems. Additionally, 20 nitrogen absorption lines are only seen in GP Com. The radial velocity variations of these lines show the same phase and velocity amplitude as the central helium emission components. The small semi-amplitude of the central helium emission component, the consistency of phase and amplitude with the absorption components in GP Com as well as the measured Stark effect shows that the central helium emission component, the so-called central-spike, is consistent with an origin on the accreting white dwarf. We use the dynamics of the bright spot and the central-spike to constrain the binary parameters for both systems and find a donor mass of 9.6-42.8 MJupiter for GP Com and 6.1-30.5 MJupiter for V396 Hya. We find an upper limit for the rotational velocity of the accretor of vrot < 46 km s-1 for GP Com and vrot < 59 km s-1 for V396 Hya which excludes a fast rotating accretor in both systems.

  7. Measurements of methane emissions from landfills using a time correlation tracer method based on FTIR absorption spectroscopy.

    PubMed

    Galle, B; Samuelsson, J; Svensson, B H; Borjesson, G

    2001-01-01

    Methane is an important climate gas contributing significantly to global warming. A large part of the anthropogenic emissions of methane comes from landfills. Due to the biogenic origin of these emissions and the inhomogeneous characteristics of landfills and their soil cover, these emissions show large spatial variation. Thus, development of reliable and cost-effective methods for measurements of these emissions is an important task and a challenge to the scientific community. Traditionally, field chamber methods have been used but also different area integrating methods based on downwind plume measurements. These measurements have been supported by meteorological data either directly from local measurements or by controlled release of tracer gas from the landfill providing the dispersion characteristics of the plume. In this paperwe describe a method,the Time Correlation Tracer method, combining controlled tracer gas release from the landfill with time-resolved concentration measurements downwind the landfill using FTIR absorption spectroscopy. The method has been tested and used on measurements at a landfill in southern Sweden over the past 1.5 years. The method has proven to be a usable method for measurements of total methane emission from landfills, and under favorable meteorological conditions we estimate an achievable accuracy of 15-30%. The real time analysis capability of the FTIR makes it possible to judge the success of the measurement already on site and to decide whether more measurements are necessary. The measurement strategy is relatively simple and straightforward, and one person can make a measurement from a medium sized landfill (1-4 ha) within a few days to a week depending on the meteorological situation.

  8. Spatially-Resolved HST GRISM Spectroscopy of a Lensed Emission Line Galaxy at Z to approximately 1

    NASA Technical Reports Server (NTRS)

    Frye, Brenda L.; Hurley, Mairead; Bowen, David V.; Meurer, Gerhardt; Sharon, Keren; Straughn, Amber; Coe, Dan; Broadhurst, Tom; Guhathakurta, Puragra

    2012-01-01

    We take advantage of gravitational lensing amplification by Abell 1689 (z=0.187) to undertake the first space-based census of emission line galaxies (ELGs) in the field of a massive lensing cluster. Forty-three ELGs are identified to a flux of i(sub 775)=27.3 via slitless grism spectroscopy. One ELG (at z=0.7895) is very bright owing to lensing magnification by a factor of approx = 4.5. Several Balmer emission lines detected from ground-based follow-up spectroscopy signal the onset of a major starburst for this low-mass galaxy (M(sub star) approx = 2 x 10(exp 9)Solar Mass) with a high specific star formation rate (approx = 20/ Gyr). From the blue emission lines we measure a gas-phase oxygen abundance consistent with solar (12+log(O /H)=8.8 +/- O.2). We break the continuous line-emitting region of this giant arc into seven approx 1 kpc bins (intrinsic size) and measure a variety of metallicity dependent line ratios. A weak trend of increasing metal fraction is seen toward the dynamical center of the galaxy. Interestingly, the metal line ratios in a region offset from the center by -lkpc have a placement on the blue HI! region excitation diagram with f([OIII]/ f(H-Beta) and f([NeIII/ f(H-Beta) that can be fit by an AGN. This asymmetrical AGN-like behavior is interpreted as a product of shocks in the direction of the galaxy's extended tail, possibly instigated by a recent galaxy interaction.

  9. Auger spectroscopy analysis in adhesion, friction and wear studies

    NASA Technical Reports Server (NTRS)

    Buckley, D. H.

    1977-01-01

    The paper reviews the current use of Auger electron spectroscopy in adhesion, friction, wear and lubrication studies. Conventional Auger spectroscopy is adopted to complement LEED studies of the adhesion of metal single crystals. In addition, Auger cylindrical mirror analysis is applied to the study of changes in surface chemistry during dynamic friction and wear experiments on polycrystalline metals and alloys. Important conclusions are that (1) segregation of alloying elements to the surface of metals can alter adhesion behavior; (2) hydrocarbons are adsorbed readily to clean iron surfaces at 23 C; (3) transfer from one surface to another for dissimilar materials in contact can be followed in sliding or rubbing friction studies; and (4) the friction process can enhance surface activity for metals with hydrocarbons.

  10. An integrated study of nutrient leaching and greenhouse gas emissions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Nutrient leaching and greenhouse gas emission are two of the primary environmental impacts of crop production. These processes have been studied at great length separately, but few integrated studies of leaching and greenhouse gas emission have been conducted. We measured nutrient leaching and green...

  11. Modeling study of natural emissions, source apportionment, and emission control of atmospheric mercury

    NASA Astrophysics Data System (ADS)

    Shetty, Suraj K.

    ) and CAMNet (Canadian Atmospheric Mercury Measurement Network). The model estimated a total deposition of 474 Mg yr-1 to the CONUS (Contiguous United States) domain, with two-thirds being dry deposited. Reactive gaseous mercury contributed the most to 60% of deposition. Emission speciation distribution is a key factor for local deposition as contribution from large point sources can be as high as 75% near (< 100 km) the emission sources, indicating that emission reduction may result in direct deposition decrease near the source locations. Among the sources, BC contributes to about 68% to 91% of total deposition. Excluding the BC's contribution, EGU contributes to nearly 50% of deposition caused by CONUS emissions in the Northeast, Southeast and East Central regions, while emissions from natural processes are more important in the Pacific and West Central regions (contributing up to 40% of deposition). The modeling results implies that implementation of the new emission standards proposed by USEPA (United States Environmental Protection Agency) would significantly benefit regions that have larger contributions from EGU sources. Control of mercury emissions from coal combustion processes has attracted great attention due to its toxicity and the emission-control regulations and has lead to advancement in state-of-the-art control technologies that alleviate the impact of mercury on ecosystem and human health. This part of the work applies a sorption model to simulate adsorption of mercury in flue gases, onto a confined-bed of activated carbon. The model's performances were studied at various flue gas flow rates, inlet mercury concentrations and adsorption bed temperatures. The process simulated a flue gas, with inlet mercury concentration of 300 ppb, entering at a velocity of 0.3 m s-1 from the bottom into a fixed bed (inside bed diameter of 1 m and 3 m bed height; bed temperature of 25 °C) of activated carbon (particle size of 0.004 m with density of 0.5 g cm-3 and

  12. Time-Resolved Emission Spectra Of Tryptophan And Proteins From Frequency-Domain Fluorescence Spectroscopy

    NASA Astrophysics Data System (ADS)

    Szmacineki, Henryk; Lakowicz, Joseph R.; Johnson, Michael L.

    1988-06-01

    We report measurements of time-resolved emission spectra of N-acetyl-L-tryptophanamide (NATA), adrenocorticotropic hormone (ACTH, residues 1-24), and of S. Nuclease. These spectra were calculated from the frequency-response of the emission, measured at several wavelengths across the emission spectra. Measurements were performed on samples not quenched and quenched by acrylamide, the latter providing additional information on the short time events. The time-resolved center-of-gravity does not decay as a single exponential. At least two spectral relaxation times are needed to account for the present data. NATA and ACTH each display relaxation times near 50 and 800 ps, which may be characteristic of exposed tryptophan residues. S. nuclease displayed slower relaxation times near 0.5 and 10 ns, which probably reflect the dynamic protein matrix which surrounds the residue.

  13. Two-dimensional correlation spectroscopy in polymer study

    PubMed Central

    Park, Yeonju; Noda, Isao; Jung, Young Mee

    2015-01-01

    This review outlines the recent works of two-dimensional correlation spectroscopy (2DCOS) in polymer study. 2DCOS is a powerful technique applicable to the in-depth analysis of various spectral data of polymers obtained under some type of perturbation. The powerful utility of 2DCOS combined with various analytical techniques in polymer studies and noteworthy developments of 2DCOS used in this field are also highlighted. PMID:25815286

  14. X-ray emission spectroscopy of cerium across the γ-α volume collapse transition.

    PubMed

    Lipp, M J; Sorini, A P; Bradley, J; Maddox, B; Moore, K T; Cynn, H; Devereaux, T P; Xiao, Y; Chow, P; Evans, W J

    2012-11-09

    High-pressure x-ray emission measurements are used to provide crucial evidence in the longstanding debate over the nature of the isostructural (α, γ) volume collapse in elemental cerium. Extended local atomic model calculations show that the satellite of the Lγ emission line offers direct access to the total angular momentum observable (J(2)). This satellite experiences a 30% steplike decrease across the volume collapse, validating the Kondo model in conjunction with previous measurements. Direct comparisons are made with previous predictions by dynamical mean field theory. A general experimental methodology is demonstrated for analogous work on a wide range of strongly correlated f-electron systems.

  15. Selective detection of carbon-13-labeled compounds by gas chromatography/emission spectroscopy

    SciTech Connect

    Quimby, B.D.; Dryden, P.C.; Sullivan, J.J. )

    1990-11-15

    This paper describes a technique which also provides selective GC detection of compounds with excess {sup 13}C content. Molecular emission from CO bands in the vacuum ultraviolet region is monitored with an atomic emission detector (AED) (4,5). Samples can also be analyzed for C, H, O, N, S, P, Cl, F, etc. by changing the reagent and makeup gas flows. This combination of {sup 13}C specificity with atomic information is useful in the identification of unknown compounds, especially when combined with mass spectral data, as shown by Hooker and DeZwaan (6).

  16. Photo field-emission spectroscopy of optical transitions in the band structure of rhenium

    NASA Astrophysics Data System (ADS)

    Radoń, T.; Kleint, Ch.

    1984-09-01

    Photo field-emission (PFE) current-voltage curves of clean and barium covered rhenium have been determined with an argon ion laser and phase sensitive detection. Field strength and work function were obtained from Fowler-Nordheim plots of the field emission currents. According to a two-step PFE model the knees of the PFE characteristics are ascribed to optical transitions in the Brillouin zone near the Fermi level. Most of the observed excitations could be correlated to direct transitions in the rhenium band structure as calculated by Mattheiss including spin-orbit coupling.

  17. Spin Transition of Iron and Crystal Structure in FeO from X-ray Emission Spectroscopy and Diffraction Measurements

    NASA Astrophysics Data System (ADS)

    Ozawa, H.; Hirose, K.; Ishii, H.; Hiraoka, N.; Ohishi, Y.

    2010-12-01

    FeO is definitely an important component in the Earth’s core because of high oxygen solubility into liquid iron at high pressure. High-pressure behavior of FeO is, therefore, of our great interest to geophysics. However, phase relationships in FeO at high pressure and high temperature still remain controversial, which is mainly due to lack of information on magnetic state of iron. The spin state of iron in FeO has been experimentally investigated by Mössbauer spectroscopy and X-ray emission spectroscopy (XES) to Mbar pressures [Pasternak et al., 1997 PRL; Badro et al., 1999 PRL]. However, there is a discrepancy between these studies probably because of sluggish structural transition at room temperature from rhombohedral to NiAs-type (B8) in FeO. Here we examined the spin state of iron and the crystal structure in FeO with combination of XES and X-ray diffraction (XRD) measurements at SPring-8. Starting material was commercially available Fe0.95O powder. The high-pressure phases of FeO were synthesized at high pressure and high temperature using a laser-heated diamond-anvil cell and examined by in-situ XRD measurements. XES spectra of the Fe Kβ fluorescence lines were collected up to 146 GPa. At 36 GPa, FeO with rhombohedral structure shows high-spin state, which is consistent with the previous studies. The satellite peak Kβ’ of iron in B8 phase completely disappeared at 146 GPa, indicating the loss of the 3d magnetic moment. We further collected XES spectra at 119 and 103 GPa with decreasing pressure. The presence of the Kβ’ peak of iron in B8 phase was clearly observed at 103 GPa whereas it was absent at 119 GPa, which suggests that the spin collapse occurred between these pressures. Furthermore, the volume measurements of B8 phase were conducted at P=77-132 GPa and 88-139 GPa at T=300 K and 1500-1700 K, respectively, using in-situ XRD. Sharp density discontinuity was observed at around 120 GPa at both 300 K and 1500-1700 K, which is most likely

  18. In situ calibration of inductively coupled plasma-atomic emission and mass spectroscopy

    DOEpatents

    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.

  19. Amateur Spectroscopy of Hot Stars. Long term tracking of circumstellar emission

    NASA Astrophysics Data System (ADS)

    Pollmann, E.

    2005-12-01

    The spectroscopic monitoring programs carried out by the Spectroscopy Group of the German ``Vereinigung der Sternfreunde'' are reviewed in light of current research. Potential benefits for the professional community in collaborating and obtain long-term monitoring data otherwise unaccessible due to telescope time restrictions are summarized. The contribution highlights results on specific objects of wide interest, such as the well investigated Be stars zeta Tauri or the S Doradus type variable P Cygni.

  20. In situ diagnosis of pulsed UV laser surface ablation of tungsten carbide hardmetal by using laser-induced optical emission spectroscopy

    NASA Astrophysics Data System (ADS)

    Li, Tiejun; Lou, Qihong; Wei, Yunrong; Huang, Feng; Dong, Jingxing; Liu, Jingru

    2001-12-01

    Surface ablation of cobalt cemented tungsten carbide hardmetal with pulsed UV laser has been in situ diagnosed by using the technique of laser-induced optical emission spectroscopy. The dependence of emission intensity of cobalt lines on number of laser shots was investigated at laser fluence of 2.5 J/cm 2. As a comparison, the reliance of emission intensity of cobalt lines as a function of laser pulse number by using pure cobalt as ablation sample was also studied at the same laser condition. It was found that for surface ablation of tungsten carbide hardmetal at laser fluence of 2.5 J/cm 2, the intensities of cobalt lines fell off dramatically in the first 300 consecutive laser shots and then slowed down to a low stable level with even more shots. For surface ablation of pure cobalt at the same laser condition, the intensities of cobalt lines remained constant more or less even after 500 laser shots and then reduced very slowly with even more shots. It was concluded that selective evaporation of cobalt at this laser fluence should be responsible for the dramatic fall-off of cobalt lines with laser shots accumulation for surface ablation of tungsten carbide hardmetal. In contrast, for surface ablation of pure cobalt, the slow reduction of cobalt lines with pulse number accumulation should be due to the formation of laser-induced crater effect.

  1. Potential radionuclide emissions from stacks on the Hanford site, Part 2: Dose assessment methodology using portable low-resolution gamma spectroscopy

    SciTech Connect

    Barnett, J.M.

    1995-02-01

    In September 1992, the Westinghouse Hanford Company began developing an in situ measurement method to assess gamma radiation emanating from high-efficiency particulate air filters using portable low-resolution gamma spectroscopy. The purpose of the new method was to assess radioactive exhaust stack air emissions from empirical data rather than from theoretical models and to determine the potential unabated dose to an offsite theoretical maximally exposed individual. In accordance with Title 40, Code of Federal Regulations, Part 61, Subpart H, {open_quotes}National Emission Standards for Hazardous Air Pollutants{close_quotes}, stacks that have the potential to emit {ge} 1 {mu}Sv y{sup {minus}1} (0.1 mrem y{sup {minus}1}) to the maximally exposed individual are considered {open_quotes}major{close_quotes} and must meet the continuous monitoring requirements. After the method was tested and verified, the U.S. Environmental Protection Agency, Region 10, approved its use in June 1993. Of the 125 stacks operated by the Westinghouse Hanford Company, 22 were targeted for evaluation by this method, and 15 were assessed. (The method could not be applied at seven stacks because of excessive background radiation or because no gamma emitting particles appear in the emission stream.) The most significant result from this study was the redesignation of the T Plant main stack. The stack was assessed as being {open_quotes}minor{close_quotes}, and it now only requires periodic confirmatory measurements and meets federally imposed sampling requirements.

  2. Tunable All Reflective Spatial Heterodyne Spectroscopy, A Technique For High Resolving Power Observation OI Defused Emission Line Sources

    NASA Astrophysics Data System (ADS)

    Hosseini, Seyedeh Sona

    The solar system presents a challenge to spectroscopic observers, because it is an astrophysically low energy environment populated with often angularly extended targets (e.g, interplanetary medium, comets, planetary upper atmospheres, and planet and satellite near space environments). Spectroscopy is a proven tool for determining compositional and other properties of remote objects. Narrow band imaging and low resolving spectroscopic measurements provide information about composition, photochemical evolution, energy distribution and density. The extension to high resolving power provides further access to temperature, velocity, isotopic ratios, separation of blended sources, and opacity effects. The drawback of high-resolution spectroscopy comes from the instrumental limitations of lower throughput, the necessity of small entrance apertures, sensitivity, field of view, and large physical instrumental size. These limitations quickly become definitive for faint and/or extended targets and for spacecraft encounters. An emerging technique with promise for the study of faint, extended sources at high resolving power is the all-reflective form of the Spatial Heterodyne Spectrometer (SHS). SHS instruments are compact and naturally possess both high etendue and high resolving power. To achieve similar spectral grasp, grating spectrometers require big telescopes. SHS is a common-path beam Fourier transform interferometer that produces Fizeau fringe pattern for all other wavelengths except the tuned wavelength. Compared to similar Fourier transform Spectrometers (FTS), SHS has considerably relaxed optical tolerances that make it easier to use in the visible and UV spectral ranges. The large etendue of SHS instruments makes them ideal for observations of extended, low surface brightness, isolated emission line sources, while their intrinsically high spectral resolution enables the study of the dynamical and spectral characteristics described above. SHS also combines very

  3. Optically active substituted polyacetylene@carbon nanotube hybrids: Preparation, characterization and infrared emissivity property study

    SciTech Connect

    Bu, Xiaohai; Zhou, Yuming Zhang, Tao; Wang, Yongjuan; Zhang, Zewu; He, Man

    2014-08-15

    Optically active substituted polyacetylene@multiwalled carbon nanotubes (SPA@MWCNTs) nanohybrids were fabricated by wrapping helical SPA copolymers onto the surface of modified nanotubes through ester bonding linkage. SPA copolymer based on chiral phenylalanine and serine was pre-polymerized by a rhodium zwitterion catalyst in THF, and evidently proved to possess strong optical activity and adopt a predominately one-handed helical conformation. Various characterizations including Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and transmission electron microscopy (TEM) demonstrated that the SPA had been covalently grafted onto the nanotubes without destroying their original graphite structure. The wrapped SPA was found to exhibit an enhancement in thermal stability and still maintained considerable optical activity after grafting. The infrared emissivity property of the nanohybrids at 8–14 μm was investigated in addition. The results indicated that the SPA@MWCNTs hybrid matrix could possess a much lower infrared emissivity value (ε=0.707) than raw MWCNTs, which might be due to synergistic effect of the unique helical conformation of optically active SPA and strengthened interfacial interaction between the organic polymers and inorganic nanoparticles. - Graphical abstract: Optically active SPA@MWCNTs nanohybrids with low infrared emissivity. - Highlights: • Synthesis of optically active SPA copolymer derived from serine and phenylalanine. • Preparation and characterization of optically active SPA@MWCNTs nanohybrids. • Application study of the SPA@MWCNTs nanohybrids (ε=0.707) in lowering the infrared emissivity.

  4. Optical emission spectroscopy of glow, Townsend-like and radiofrequency DBDs in an Ar/NH3 mixture

    NASA Astrophysics Data System (ADS)

    Bazinette, R.; Paillol, J.; Massines, F.

    2015-10-01

    Three homogeneous DBD modes have been observed in argon ammonia Penning mixture. The transition from glow to Townsend-like to radiofrequency modes happens when the frequency increases from 50 kHz and 9.6 MHz. The aim of this paper is to characterize these modes based on the study of optical emission spectra. The transition from glow mode to Townsend-like mode is characterized by stronger argon emissions associated to higher energetic electrons. The radio-frequency mode is characterized by a continuum in the UV-vis range. This continuum is attributed to bremsstrahlung emission. Its presence is explained by a high density of less energetic electrons which is consistent with a decrease of argon emissions and an increase of the NH 336 nm system associated with electrons of low energy.

  5. Environmental Affects on Surfactin Studied Using Multidimensional Infrared Spectroscopy

    NASA Astrophysics Data System (ADS)

    Nite, Jacob; Krummel, Amber

    2014-03-01

    Surfactin, a cyclic lipopeptide produced by Bacillus subtilis, is a pore forming toxin that has been studied in the literature extensively. It is known to exist in two different conformations, S1 and S2, which are thought to relate to surfactin's pore forming ability. The vibrational characteristics of surfactin have been studied using linear infrared spectroscopy as well as two-dimensional infrared spectroscopy in different environments. The environments probed were specifically chosen to mimic surfactin in an aqueous environment as well as a lipid membrane environment. The vibrational spectra were interpreted using transitional dipole coupling to relate the coupling evident in the data to the structural conformers obtained from NMR data. These measurements have been used to link the structural characteristics of surfactin to different solvent environments to gain insight into surfactin's pore forming ability mechanisms. Colorado State University. Maciel Fellowship.

  6. Setup for in situ investigation of gases and gas/solid interfaces by soft x-ray emission and absorption spectroscopy

    SciTech Connect

    Benkert, A. E-mail: l.weinhardt@kit.edu; Blum, M.; Meyer, F.; Wilks, R. G.; Yang, W.; Bär, M.; and others

    2014-01-15

    We present a novel gas cell designed to study the electronic structure of gases and gas/solid interfaces using soft x-ray emission and absorption spectroscopies. In this cell, the sample gas is separated from the vacuum of the analysis chamber by a thin window membrane, allowing in situ measurements under atmospheric pressure. The temperature of the gas can be regulated from room temperature up to approximately 600 °C. To avoid beam damage, a constant mass flow can be maintained to continuously refresh the gaseous sample. Furthermore, the gas cell provides space for solid-state samples, allowing to study the gas/solid interface for surface catalytic reactions at elevated temperatures. To demonstrate the capabilities of the cell, we have investigated a TiO{sub 2} sample behind a mixture of N{sub 2} and He gas at atmospheric pressure.

  7. Studies of cartilaginous tissue using Raman spectroscopy method

    NASA Astrophysics Data System (ADS)

    Timchenko, Pavel E.; Timchenko, Elena V.; Volova, Larisa T.; Dolgyshkin, Dmitry A.; Markova, Maria D.; Kylabyhova, A. Y.; Kornilin, Dmitriy V.

    2016-10-01

    The work presents the results of studies of samples of human articular surface of the knee joint, obtained by Raman spectroscopy implementedduring endoprosthesis replacement surgery . The main spectral characteristics of articular surface areas with varying degrees of cartilage damage were detected at 956 cm-1, 1066 cm-1 wavenumbers, corresponding to phosphate and carbonate, and at 1660 cm-1, 1271 cm-1 wavenumbers, corresponding to amide I and amide III. Criteria allowing to identify the degree of articular hyaline cartilage damage were introduced.

  8. Atomic photoelectron-spectroscopy studies using synchrotron radiation

    SciTech Connect

    Kobrin, P.H.

    1983-02-01

    Photoelectron spectroscopy combined with tunable synchrotron radiation has been used to study the photoionization process in several atomic systems. The time structure of the synchrotron radiation source at the Stanford Synchrotron Radiation Laboratory (SSRL) was used to record time-of-flight (TOF) photoelectron spectra of gaseous Cd, Hg, Ne, Ar, Ba, and Mn. The use of two TOF analyzers made possible the measurement of photoelectron angular distributions as well as branching ratios and partial cross sections.

  9. Spectroscopy of emission-line nebulae in powerful radio galaxies - Interpretation

    NASA Astrophysics Data System (ADS)

    Baum, S. A.; Heckman, T. M.; van Breugel, W.

    1992-04-01

    Long-slit optical spectra of the emission-line nebulae associated with 21 low-redshift (less than 0.2) radio galaxies are analyzed. Nebulae are classified kinematically into three types: rotators, calm nonrotators, and violent nonrotators; these types are characterized. It is proposed that the rotators have dynamically young disks of gas recently acquired by the radio galaxy in an interaction or merger with a gas-rich galaxy. This is consistent with the data on the morphologies, colors, and stellar dynamics of radio galaxies with strong emission lines. It is inferred from the association of the large-scale gas kinematics with the radio and optical properties of an active galaxy that the angular momentum of the gas which fuels the AGN may be an important parameter in the determinant of how activity is manifest in an AGN.

  10. In situ calibration of inductively coupled plasma-atomic emission and mass spectroscopy

    DOEpatents

    Braymen, S.D.

    1996-06-11

    A method and apparatus are disclosed 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 in situ calibration technique is suitable for various remote, on-site sampling systems such as laser ablation or nebulization. 5 figs.

  11. Emission Spectroscopy of the Interior of Optically Dense Post-Detonation Fireballs

    DTIC Science & Technology

    2013-03-01

    the dynamics occurring in the interior of the fireball. Emission spectra are collected following detonation of 20 g aluminized Hexahydro-1,3,5...detonation of 20 g aluminized Hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) charges using fiber optics located behind the flame front and then compared with...function of space and time for aluminized explosives, with characteristic attenua- tion depths on the order of millimeters for its early evolution and

  12. Comparative measurements of mineral elements in milk powders with laser-induced breakdown spectroscopy and inductively coupled plasma atomic emission spectroscopy.

    PubMed

    Lei, W Q; El Haddad, J; Motto-Ros, V; Gilon-Delepine, N; Stankova, A; Ma, Q L; Bai, X S; Zheng, L J; Zeng, H P; Yu, J

    2011-07-01

    Mineral elements contained in commercially available milk powders, including seven infant formulae and one adult milk, were analyzed with inductively coupled plasma atomic emission spectrometry (ICP-AES) and laser-induced breakdown spectroscopy (LIBS). The purpose of this work was, through a direct comparison of the analytical results, to provide an assessment of the performance of LIBS, and especially of the procedure of calibration-free LIBS (CF-LIBS), to deal with organic compounds such as milk powders. In our experiments, the matrix effect was clearly observed affecting the analytical results each time laser ablation was employed for sampling. Such effect was in addition directly observed by determining the physical parameters of the plasmas induced on the different samples. The CF-LIBS procedure was implemented to deduce the concentrations of Mg and K with Ca as the internal reference element. Quantitative analytical results with CF-LIBS were validated with ICP-AES measurements and nominal concentrations specified for commercial milks. The obtained good results with the CF-LIBS procedure demonstrate its capacity to take into account the difference in physical parameters of the plasma in the calculation of the concentrations of mineral elements, which allows a significant reduction of the matrix effect related to laser ablation. We finally discuss the way to optimize the implementation of the CF-LIBS procedure for the analysis of mineral elements in organic materials.

  13. Measurements of fluoride emissions in aluminum smelters by tunable diode laser spectroscopy

    SciTech Connect

    Schiff, H.; Pisano, J.; Chanda, A.; Karecki, D.; Mackay, G.

    1999-07-01

    Tunable Diode Laser Absorption Spectrometry (TDLAS) is an effective method for measuring the emissions of fluoride compounds from primary aluminum production. Hydrogen fluoride is a highly toxic substance, harmful to both human health and the environment. The perfluorocarbons, CF{sub 4} and C{sub 2}F{sub 6}, are strong greenhouse gases with atmospheric lifetimes of more than 5,000 years. The LasIR systems based on near infrared tunable diode lasers have been used to measure HF in stacks, on both sides of scrubbers and in the pot-rooms of the smelter. Examples of these measurements are presented. The perfluorocarbons have been measured with a mid infrared TDLAS system by continuous extraction into a multipath White cell. Earlier measurements by this method clearly revealed the factors, which govern perfluorocarbon emissions and have led to improvement in aluminum production technology. Recent measurements have shown that the use of these technologies does, in fact, result in appreciable reduction in the emissions of the perfluorocarbons. The examples given in this paper demonstrate the ability and versatility of TDLAS systems for providing reliable, interference-free measurements of important gases in a complex mixture and in hostile environments.

  14. Diagnostics and Monitoring of a Plasma Beam Source based on Optical Emission Spectroscopy

    NASA Astrophysics Data System (ADS)

    Harhausen, Jens; Foest, Rüdiger; Loffhagen, Detlef; Ohl, Andreas; Schäfer, Jan

    2013-09-01

    Plasma ion assisted deposition (PIAD) is employed for the production of high performance optical coatings. Here, the assist-source is a hot cathode DC discharge (Advanced Plasma Source APS) which generates an ion beam (ion energy Ei ~ 50 - 150eV) based on an expansion process at a chamber pressure of p ~ 20mPa . Efforts in plasma characterization have been made to improve the PIAD concept in terms of quality and reproducibility. In this contribution results on the electron energy distribution function (EEDF) and local emission of argon neutral and ion species in the plasma plume are presented. The interpretation of emission is supported by collisional radiative modeling. Main findings are the occurrence of a nonlocal EEDF and an inhomogeneous distribution of emission which is sensitive to the conditioning of the APS, like the cathode temperature. This detailed view allows a novel approach to monitor the plasma state in this particular deposition environment along with employing a control scheme for PIAD. First results obtained for oxide layers (TiO2, Al2O3) are discussed. Funded by the German Ministry for Education and Research (BMBF, Fkz. 13N10462).

  15. Characteristics of TiNi Thin Films Deposited by Magnetron Sputtering System with Optical Emission Spectroscopy Monitor

    NASA Astrophysics Data System (ADS)

    Liu, Erqiang; Bao, Mingdong; Yuan, Guozheng; Xiao, Gesheng; Jin, Tao; Li, Zhigang; Shu, Xuefeng

    2015-07-01

    TiNi composite thin films were fabricated using a closed-field unbalanced magnetron sputtering system equipped with optical emission spectroscopy monitor (OEM). The thin films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and nanoindentation. Results show that the TiNi films are amorphous, and their composition varies approximately linearly with the OEM value. Thus, the film composition could be controlled by in situ real-time OEM. The structure of the single B2 parent phase was observed in the annealed TiNi film. The hardness and elastic modulus of the films increased because of the precipitation of the Ti3Ni4 phase in the single B2 parent phase.

  16. Laser interferometry and emission spectroscopy measurements of cold-sprayed copper thermite shocked to 35 GPa

    NASA Astrophysics Data System (ADS)

    Neel, Christopher; Lacina, David; Johnson, Stephanie

    2017-01-01

    Plate impact experiments were conducted on a cold-sprayed Al-CuO thermite at peak stresses between 5-35 GPa to determine the Hugoniot curve and characterize any shock induced energetic reaction. Photon Doppler Velocimetry (PDV) measurements were used to obtain particle velocity histories and shock speed information for both the shock loading and unloading behavior of the material. A jump in shock velocity was observed in the Hugoniot curve when the material was shocked beyond 20 GPa, suggesting a volume-increasing reaction occurs in this shocked Al-CuO thermite near 20 GPa. To better characterize any shock-induced thermite reactions, emission spectroscopy measurements were obtained at stresses above 20 GPa. The best time-resolved spectra obtained thus far, at 25 GPa, does not support the fast thermite reaction hypothesis.

  17. Resonant soft X-ray emission spectroscopy of vanadium oxides andrelated compounds

    SciTech Connect

    Schmitt, Thorsten

    2004-01-01

    In today's information world, bits of data are processed by semiconductor chips, and stored in the magnetic disk drives. But tomorrow's information technology may see magnetism (spin) and semiconductivity (charge) combined in one ''spintronic'' device that exploits both charge and ''spin'' to carry data (the best of two worlds). Spintronic devices such as spin valve transistors, spin light emitting diodes, non-volatile memory, logic devices, optical isolators and ultra-fast optical switches are some of the areas of interest for introducing the ferromagnetic properties at room temperature in a semiconductor to make it multifunctional. The potential advantages of such spintronic devices will be higher speed, greater efficiency, and better stability at a reduced power consumption. This Thesis contains two main topics: In-depth understanding of magnetism in Mn doped ZnO, and our search and identification of at least six new above room temperature ferromagnetic semiconductors. Both complex doped ZnO based new materials, as well as a number of nonoxides like phosphides, and sulfides suitably doped with Mn or Cu are shown to give rise to ferromagnetism above room temperature. Some of the highlights of this work are discovery of room temperature ferromagnetism in: (1) ZnO:Mn (paper in Nature Materials, Oct issue, 2003); (2) ZnO doped with Cu (containing no magnetic elements in it); (3) GaP doped with Cu (again containing no magnetic elements in it); (4) Enhancement of Magnetization by Cu co-doping in ZnO:Mn; and (5) CdS doped with Mn, and a few others not reported in this thesis. We discuss in detail the first observation of ferromagnetism above room temperature in the form of powder, bulk pellets, in 2-3 μm thick transparent pulsed laser deposited films of the Mn (< 4 at.%) doped ZnO. High-resolution transmission electron microscopy (HRTEM) and electron energy loss spectroscopy (EELS) spectra recorded from 2 to 200nm areas showed homogeneous distribution of Mn

  18. Low-energy d-d excitations in MnO studied by resonant x-ray fluorescence spectroscopy

    SciTech Connect

    Butorin, S.M.; Guo, J.; Magnuson, M.

    1997-04-01

    Resonant soft X-ray emission spectroscopy has been demonstrated to possess interesting abilities for studies of electronic structure in various systems, such as symmetry probing, alignment and polarization dependence, sensitivity to channel interference, etc. In the present abstract the authors focus on the feasibility of resonant soft X-ray emission to probe low energy excitations by means of resonant electronic X-ray Raman scattering. Resonant X-ray emission can be regarded as an inelastic scattering process where a system in the ground state is transferred to a low excited state via a virtual core excitation. The energy closeness to a core excitation of the exciting radiation enhances the (generally) low probability for inelastic scattering at these wavelengths. Therefore soft X-ray emission spectroscopy (in resonant electronic Raman mode) can be used to study low energy d-d excitations in transition metal systems. The involvement of the intermediate core state allows one to use the selection rules of X-ray emission, and the appearance of the elastically scattered line in the spectra provides the reference to the ground state.

  19. Flash Spectroscopy: Emission Lines from the Ionized Circumstellar Material Around <10-Day-Old Type II Supernovae

    DOE PAGES

    Khazov, Daniel; Yaron, O.; Gal-Yam, A.; ...

    2016-02-02

    Supernovae (SNe) embedded in dense circumstellar material (CSM) may show prominent emission lines in their early-time spectra (≤10 days after the explosion), owing to recombination of the CSM ionized by the shock-breakout flash. From such spectra ("flash spectroscopy"), we can measure various physical properties of the CSM, as well as the mass-loss rate of the progenitor during the year prior to its explosion. In this paper, by searching through the Palomar Transient Factory (PTF and iPTF) SN spectroscopy databases from 2009 through 2014, we found 12 SNe II showing flash-ionized (FI) signatures in their first spectra. All are younger thanmore » 10 days. These events constitute 14% of all 84 SNe in our sample having a spectrum within 10 days from explosion, and 18% of SNe II observed at ages <5 days, thereby setting lower limits on the fraction of FI events. We classified as "blue/featureless" (BF) those events having a first spectrum that is similar to that of a blackbody, without any emission or absorption signatures. It is possible that some BF events had FI signatures at an earlier phase than observed, or that they lack dense CSM around the progenitor. Within 2 days after explosion, 8 out of 11 SNe in our sample are either BF events or show FI signatures. Finally and interestingly, we found that 19 out of 21 SNe brighter than an absolute magnitude MR = -18.2 belong to the FI or BF groups, and that all FI events peaked above MR = -17.6 mag, significantly brighter than average SNe II.« less

  20. Flash Spectroscopy: Emission Lines from the Ionized Circumstellar Material Around <10-Day-Old Type II Supernovae

    SciTech Connect

    Khazov, Daniel; Yaron, O.; Gal-Yam, A.; Manulis, I.; Rubin, A.; Kulkarni, S. R.; Arcavi, I.; Kasliwal, M. M.; Ofek, E. O.; Cao, Y.; Perley, D.; Sollerman, J.; Horesh, A.; Sullivan, M.; Filippenko, A. V.; Nugent, P. E.; Howell, D. A.; Cenko, S. B.; Silverman, J. M.; Ebeling, H.; Taddia, F.; Johansson, J.; Laher, R. R.; Surace, J.; Rebbapragada, U. D.; Wozniak, Przemyslaw R.; Matheson, T.

    2016-02-02

    Supernovae (SNe) embedded in dense circumstellar material (CSM) may show prominent emission lines in their early-time spectra (≤10 days after the explosion), owing to recombination of the CSM ionized by the shock-breakout flash. From such spectra ("flash spectroscopy"), we can measure various physical properties of the CSM, as well as the mass-loss rate of the progenitor during the year prior to its explosion. In this paper, by searching through the Palomar Transient Factory (PTF and iPTF) SN spectroscopy databases from 2009 through 2014, we found 12 SNe II showing flash-ionized (FI) signatures in their first spectra. All are younger than 10 days. These events constitute 14% of all 84 SNe in our sample having a spectrum within 10 days from explosion, and 18% of SNe II observed at ages <5 days, thereby setting lower limits on the fraction of FI events. We classified as "blue/featureless" (BF) those events having a first spectrum that is similar to that of a blackbody, without any emission or absorption signatures. It is possible that some BF events had FI signatures at an earlier phase than observed, or that they lack dense CSM around the progenitor. Within 2 days after explosion, 8 out of 11 SNe in our sample are either BF events or show FI signatures. Finally and interestingly, we found that 19 out of 21 SNe brighter than an absolute magnitude MR = -18.2 belong to the FI or BF groups, and that all FI events peaked above MR = -17.6 mag, significantly brighter than average SNe II.

  1. Raman spectroscopy and immunohistochemistry for schwannoma characterization: a case study

    NASA Astrophysics Data System (ADS)

    Neto, Lazaro P. M.; das Chagas, Maurilio J.; Carvalho, Luis Felipe C. S.; Ferreira, Isabelle; dos Santos, Laurita; Haddad, Marcelo; Loddi, Vinicius; Martin, Airton A.

    2016-03-01

    The schwannomas is a tumour of the tissue that covers nerves, called the nerve sheath. Schwannomas are often benign tumors of the Schwan cells, which are the principal glia of the peripheral nervous system (PNS). Preoperative diagnosis of this lesion usually is difficult, therefore, new techniques are being studied as pre surgical evaluation. Among these, Raman spectroscopy, that enables the biochemical identification of the tissue analyzed by their optical properties, may be used as a tool for schwannomas diagnosis. The aim of this study was to discriminate between normal nervous tissue and schwannoma through the confocal Raman spectroscopy and Raman optical fiber-based techniques combined with immunohistochemical analysis. Twenty spectra were analyzed from a normal nerve tissue sample (10) and schwannoma (10) by Holospec f / 1.8 (Kayser Optical Systems) coupled to an optical fiber with a 785nm laser line source. The data were pre-processed and vector normalized. The average analysis and standard deviation was performed associated with cluster analysis. AML, 1A4, CD34, Desmin and S-100 protein markers were used for immunohistochemical analysis. Immunohistochemical analysis was positive only for protein S-100 marker which confirmed the neural schwanomma originality. The immunohistochemistry analysis were important to determine the source of the injury, whereas Raman spectroscopy were able to differentiated tissues types indicating important biochemical changes between normal and benign neoplasia.

  2. Authentication of the botanical origin of honey by front-face fluorescence spectroscopy. A preliminary study.

    PubMed

    Ruoff, Kaspar; Karoui, Romdhane; Dufour, Eric; Luginbühl, Werner; Bosset, Jacques-Olivier; Bogdanov, Stefan; Amado, Renato

    2005-03-09

    The potential of front-face fluorescence spectroscopy for the authentication of unifloral and polyfloral honey types (n = 57 samples) previously classified using traditional methods such as chemical, pollen, and sensory analysis was evaluated. Emission spectra were recorded between 280 and 480 nm (excit: 250 nm), 305 and 500 nm (excit: 290 nm), and 380 and 600 nm (excit: 373 nm) directly on honey samples. In addition, excitation spectra (290-440 nm) were recorded with the emission measured at 450 nm. A total of four different spectral data sets were considered for data analysis. After normalization of the spectra, chemometric evaluation of the spectral data was carried out using principal component analysis (PCA) and linear discriminant analysis (LDA). The rate of correct classification ranged from 36% to 100% by using single spectral data sets (250, 290, 373, 450 nm) and from 73% to 100% by combining these four data sets. For alpine polyfloral honey and the unifloral varieties investigated (acacia, alpine rose, honeydew, chestnut, and rape), correct classification ranged from 96% to 100%. This preliminary study indicates that front-face fluorescence spectroscopy is a promising technique for the authentication of the botanical origin of honey. It is nondestructive, rapid, easy to use, and inexpensive. The use of additional excitation wavelengths between 320 and 440 nm could increase the correct classification of the less characteristic fluorescent varieties.

  3. Time-and-state resolved spectroscopy, diffraction, and circular dichroism in core photoelectron emission from clean and oxygen-covered W(110)

    SciTech Connect

    Ynzunza, Ramon Xavier

    1998-10-01

    Several aspects of core-level photoelectron emission fi-om solid surfaces as excited by high-brightness variable-polarization synchrotrons radiation have been studied with a new beamline and experimental station at the Advanced Light Source in Berkeley. These include: resolution of different chemical states and site types via high-resolution photoelectron spectroscopy (PS), the use of state-resolved photoelectron difllaction (PD) to determine local atomic geometries, and the observation and analysis of circular dichroism (CD) effects in photoelectron diffraction. These methods have been applied to clean and oxygen-exposed surfaces of W(110). Full-solid-angle photoelectron diffraction from clean W(110) was measured, with the surface and bulk atoms being clearly resolved.

  4. Analysis of the absorption spectra of gas emission of patients with lung cancer and chronic obstructive pulmonary disease by laser optoacoustic spectroscopy

    NASA Astrophysics Data System (ADS)

    Bukreeva, Ekaterina B.; Bulanova, Anna A.; Kistenev, Yurii V.; Kuzmin, Dmitry A.; Tuzikov, Sergei A.; Yumov, Evgenii L.

    2013-02-01

    It is important to identify patients with chronic obstructive pulmonary disease (COPD) and lung cancer in the early stages of the disease. The method of laser opto-acoustic gas analysis, in this case, can act as a promising tool for diagnostics. The material for this study were the gas emission samples collected from patients and healthy volunteers - samples of exhaled air, swabs from teeth and cheeks. A set of material was formed three groups: healthy volunteers, patients with COPD, lung cancer patients. The resulting samples were analyzed by means of laser opto-acoustic gas analyzers: with intracavity location detector (ILPA-1), with extracavity location detector (LGA-2). Presentation of the results in an easy to visual form was performed using the method of elastic maps, based on the principal component analysis. The results of analysis show potentialities of usage of laser optoacoustic spectroscopy application to assess the status of patients with chronic obstructive pulmonary disease and lung cancer.

  5. Energy-dispersive x-ray fluorescence spectroscopy and inductively coupled plasma emission spectrometry evaluated for multielement analysis in complex biological matrices.

    PubMed

    Irons, R D; Schenk, E A; Giauque, R D

    1976-12-01

    Energy-dispersive x-ray spectroscopy and inductively coupled plasma emission spectrometry were evaluated as methods for routine multielement analysis of biological material. Standard samples included Standard Reference Materials (National Bureau of Standards), compounded mixtures, and supplements that provided a wide range of elemental concentrations for analysis. Elements included in this study were Zn, Pb, Ni, Mn, Fe, Mg, Cu, Ca, As, Se, Br, Rb, and Sr. Standards were analyzed as unknowns by participating laboratories. The two methods were evaluated for sensitivity, precision, and accuracy, and the results compared to those obtained for atomic absorption spectrometric analysis of identical standard unknowns. Both methods compared favorably and both were determined to be highly reliable for such an application. Advantages and disadvantages of each method are compared and discussed.

  6. Observation of Coriolis Coupling between nu(2) + 4nu(4) and 7nu(4) in Acetylene &Xtilde;(1)Sigma(+)(g) by Stimulated Emission Pumping Spectroscopy.

    PubMed

    Moss; Duan; Jacobson; O'Brien; Field

    2000-02-01

    Stimulated emission pumping (SEP) spectroscopy has been used to examine a low energy region (E(vib) approximately 4400 cm(-1)) of &Xtilde;(1)Sigma(+)(g) acetylene at higher resolution than was possible in previous dispersed fluorescence studies. The expected bright state, nu(2) + 4nu(4), is observed to be coupled to the nearly degenerate 7nu(4) state by a Coriolis mechanism. A least-squares analysis yields values for zero-order vibrational energies, rotational constants, and a Coriolis-coupling coefficient that are all consistent with expectations. Calculated relative intensities of SEP transitions, accounting for interference due to axis-switching effects, are also consistent with observations. Implications of the observed Coriolis resonance with regard to global acetylene vibrational dynamics are also discussed. Copyright 2000 Academic Press.

  7. A top-down approach to determine carbon monoxide (CO) emissions in the Mexico Megacity using ground based FTIR solar and lunar absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Stremme, Wolfgang; Ortega, Ivan; Garcia, Agustin; Grutter, Michel

    2010-05-01

    The carbon monoxide (CO) total column has been measured by ground based solar and lunar FTIR absorption spectroscopy with 0.5 cm-1 resolution since October 2007 at the UNAM Campus in Mexico City (19,33°N, 99.18°W). The CO column density is retrieved using the SFIT2 retrieval code based on the optimal estimation theory (Rodgers 1976). The time series of the CO-column retrievals show different diurnal behaviours compared to the surface CO concentration. This is explained by the change in the vertical distribution which is dominated by the evolution of the mixing layer height (MLH). The CO column shows a diurnal and weekly pattern depending on the wind speed and traffic, but is not directly dependent on the mixing layer height. A comparison of the measured CO-column, CO-surface concentration and the reconstructed MLH with results from regional MCCM (Grell et al , 2000) model will be presented. Based on the information of the vertical structure, the surface wind fields and surface CO concentrations that are provided by LIDAR measurements, the meteorological and air quality networks, it is possible to estimate the horizontal CO-transport. The CO surface emissions can therefore be calculated from the CO column growth rate. For horizontal homogeneous conditions, the CO column density growth-rate directly gives the surface emission. A first top-down CO emission estimation is presented and compared with the official inventory (bottom-up approach) and other estimations used in recent studies on Mexico City. Monitoring of CO columns in megacities provides new information of the anthropogenic emissions on a regional scale and helps to link the understanding of the CO budget from local to the global scale.

  8. Emissions from smoldering combustion of biomass measured by open-path Fourier transform infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Yokelson, Robert J.; Susott, Ronald; Ward, Darold E.; Reardon, James; Griffith, David W. T.

    1997-08-01

    Biomass samples from a diverse range of ecosystems were burned in the Intermountain Fire Sciences Laboratory open combustion facility. Midinfrared spectra of the nascent emissions were acquired at several heights above the fires with a Fourier transform infrared spectrometer (FTIR) coupled to an open multipass cell. In this report, the results from smoldering combustion during 24 fires are presented including production of carbon dioxide, carbon monoxide, methane, ethene, ethyne, propene, formaldehyde, 2-hydroxyethanal, methanol, phenol, acetic acid, formic acid, ammonia, hydrogen cyanide, and carbonyl sulfide. These were the dominant products observed, and many have significant influence on atmospheric chemistry at the local, regional, and global scale. Included in these results are the first optical, in situ measurements of smoke composition from fires in grasses, hardwoods, and organic soils. About one half of the detected organic emissions arose from fuel pyrolysis which produces white smoke rich in oxygenated organic compounds. These compounds deserve more attention in the assessment of fire impacts on the atmosphere. The compound 2-hydroxyethanal is a significant component of the smoke, and it is reported here for the first time as a product of fires. Most of the observed alkane and ammonia production accompanied visible glowing combustion. NH3 is normally the major nitrogen-containing emission detected from smoldering combustion of biomass, but from some smoldering organic soils, HCN was dominant. Tar condensed on cool surfaces below the fires accounting for ˜1% of the biomass burned, but it was enriched in N by a factor of 6-7 over the parent material, and its possible role in postfire nutrient cycling should be further investigated.

  9. Galactic Soft X-ray Emission Revealed with Spectroscopic Study of Absorption and Emission Spectra

    NASA Astrophysics Data System (ADS)

    Yamasaki, Noriko Y.; Mitsuda, K.; Takei, Y.; Hagihara, T.; Yoshino, T.; Wang, Q. D.; Yao, Y.; McCammon, D.

    2010-03-01

    Spectroscopic study of Oxygen emission/absorption lines is a new tool to investigate the nature of the soft X-ray background. We investigated the emission spectra of 14 fields obtained by Suzaku, and detected OVII and OVIII lines separately. There is an almost isotropic OVII line emission with 2 LU intensity. As the attenuation length in the Galactic plane for that energy is short, that OVII emission should arise within 300 pc of our neighborhood. In comparison with the estimated emission measure for the local bubble, the most plausible origin of this component is the solar wind charge exchange with local interstellar materials. Another component presented from the correlation between the OVII and OVIII line intensity is a thermal emission with an apparent temperature of 0.2 keV with a field-to-field fluctuation of 10% in temperature, while the intensity varies about a factor of 4. By the combination analysis of the emission and the absorption spectra, we can investigate the density and the scale length of intervening plasma separately. We analyzed the Chanrdra grating spectra of LMC X-3 and PKS 2155-304, and emission spectra toward the line of sight by Suzaku. In both cases, the combined analysis showed that the hot plasma is not iso-thermal nor uniform. Assuming an exponential disk distribution, the thickness of the disk is as large as a few kpc. It suggests that there is a thick hot disk or hot halo surrounding our Galaxy, which is similar to X-ray hot haloes around several spiral galaxies.

  10. Determination of phosphorus in lubricating oils by cool-flame emission spectroscopy.

    PubMed

    Elliott, W N; Heathcote, C; Mostyn, R A

    1972-03-01

    The phosphorus content of lubricating oils is determined by measurement of the emission from the HPO molecular species at 528 nm in a cool hydrogen-nitrogen diffusion flame. The oil is ashed in the presence of potassium hydroxide and an aqueous extract of the melt is treated with ion-exchange resin to remove interferents, before aspiration into the flame. Analytical results are presented on samples containing phosphorus in the range 0.009-0.2%. The precision of the method is +/- 5% at the 0.04% phosphorus level.

  11. Comparison Between X-rays Absorption and Emission Spectroscopy Measurements on a Ceramic Envelop Lamp

    NASA Astrophysics Data System (ADS)

    Lafitte, Bruno; Aubes, Michel; Zissis, Georges

    2007-12-01

    Burners of metal halide lamps used for illumination are generally made of polycrystalline alumina ceramic (PCA) which is translucent to visible light. We show that the difficulty of selecting a line of sight through the lamp prevents the use of optical emission diagnostic. X-rays photons are mainly absorbed and not scattered by PCA. Absorption by mercury atoms contributing to the discharge allowed us to determine the density of mercury in the lamp. By comparing diagnostic methods, we put in evidence the difficulty of taking into account the scattering of light mathematically.

  12. Monitoring of carbon dioxide exhaust emissions using mid-infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Mulrooney, Jim; Clifford, John; Fitzpatrick, Colin; Chambers, Paul; Lewis, Elfed

    2007-06-01

    An optical fibre sensor for monitoring carbon dioxide emissions from modern road vehicles and operating in the mid-infrared spectral region is reported. The wavelength range of operation is centred at 4.23 µm and has required a novel implementation of this sensor using low cost and robust components. The sensor is shown to be capable of detecting CO2 to a minimum level of 350 ppm, to be stable over several hours of continuous operation and insensitive to the presence of other species present in the exhaust.

  13. Study Pinpoints Sources of Polluting Vehicle Emissions (Fact Sheet)

    SciTech Connect

    Not Available

    2012-03-01

    Unburned lubricant produces 60%-90% of organic carbon emissions. While diesel fuel is often viewed as the most polluting of conventional petroleum-based fuels, emissions from gasoline engines can more significantly degrade air quality. Gasoline exhaust is at least as toxic on a per-unit-mass basis as diesel exhaust, and contributes up to 10 times more particulate matter (PM) to the emission inventory. Because emissions from both fuels can gravely impact health and the environment, researchers at the National Renewable Energy Laboratory (NREL) launched a study to understand how these pollutants relate to fuels, lubricants, and engine operating conditions. NREL's Collaborative Lubricating Oil Study on Emissions (CLOSE) project tested a variety of vehicles over different drive cycles at moderate (72 F) and cold (20 F) temperatures. Testing included: (1) Normal and high-emitting light-, medium-, and heavy-duty vehicles; (2) Gasoline, diesel, and compressed natural gas (CNG)-powered vehicles; (3) New and aged lubricants representative of those currently on the market; and (4) Gasoline containing no ethanol, E10, Texas-mandated low-emission diesel fuel, biodiesel, and CNG. The study confirmed that normally functioning emission control systems for gasoline light-duty vehicles are very effective at controlling organic carbon (OC) emissions. Diesel vehicles without aftertreatment emission control systems exhibited OC emissions approximately one order of magnitude higher than gasoline vehicles. High-emitter gasoline vehicles produced OC emissions similar to diesel vehicles without exhaust aftertreatment emission control. Exhaust catalysts combusted or converted more than 75% of lubricating oil components in the exhaust gases. Unburned crankcase lubricant made up 60%-90% of OC emissions. This OC represented 20%-50% of emitted PM in all but two of the vehicles. Three-way catalysts proved effective at reducing most of the OC. With high PM emitters or vehicles with deteriorated

  14. Optimally enhanced optical emission in laser-induced breakdown spectroscopy by combining spatial confinement and dual-pulse irradiation.

    PubMed

    Guo, L B; Zhang, B Y; He, X N; Li, C M; Zhou, Y S; Wu, T; Park, J B; Zeng, X Y; Lu, Y F

    2012-01-16

    In laser-induced breakdown spectroscopy (LIBS), a pair of aluminum-plate walls were used to spatially confine the plasmas produced in air by a first laser pulse (KrF excimer laser) from chromium (Cr) targets with a second laser pulse (Nd:YAG laser at 532 nm, 360 mJ/pulse) introduced parallel to the sample surface to re-excite the plasmas. Optical emission enhancement was achieved by combing the spatial confinement and dual-pulse LIBS (DP-LIBS), and then optimized by adjusting the distance between the two walls and the interpulse delay time between both laser pulses. A significant enhancement factor of 168.6 for the emission intensity of the Cr lines was obtained at an excimer laser fluence of 5.6 J/cm(2) using the combined spatial confinement and DP-LIBS, as compared with an enhancement factor of 106.1 was obtained with DP-LIBS only. The enhancement mechanisms based on shock wave theory and reheating in DP-LIBS are discussed.

  15. [Near infrared spectroscopy study on water content in turbine oil].

    PubMed

    Chen, Bin; Liu, Ge; Zhang, Xian-Ming

    2013-11-01

    Near infrared (NIR) spectroscopy combined with successive projections algorithm (SPA) was investigated for determination of water content in turbine oil. Through the 57 samples of different water content in turbine oil scanned applying near infrared (NIR) spectroscopy, with the water content in the turbine oil of 0-0.156%, different pretreatment methods such as the original spectra, first derivative spectra and differential polynomial least squares fitting algorithm Savitzky-Golay (SG), and successive projections algorithm (SPA) were applied for the extraction of effective wavelengths, the correlation coefficient (R) and root mean square error (RMSE) were used as the model evaluation indices, accordingly water content in turbine oil was investigated. The results indicated that the original spectra with different water content in turbine oil were pretreated by the performance of first derivative + SG pretreatments, then the selected effective wavelengths were used as the inputs of least square support vector machine (LS-SVM). A total of 16 variables selected by SPA were employed to construct the model of SPA and least square support vector machine (SPA-LS-SVM). There is 9 as The correlation coefficient was 0.975 9 and the root of mean square error of validation set was 2.655 8 x 10(-3) using the model, and it is feasible to determine the water content in oil using near infrared spectroscopy and SPA-LS-SVM, and an excellent prediction precision was obtained. This study supplied a new and alternative approach to the further application of near infrared spectroscopy in on-line monitoring of contamination such as water content in oil.

  16. Fluorescence spectroscopy to discriminate neoplastic human brain lesions: a study using the spectral intensity ratio and multivariate linear discriminant analysis

    NASA Astrophysics Data System (ADS)

    Nazeer, Shaiju S.; Saraswathy, Ariya; Gupta, Arun Kumar; Jayasree, Ramapurath S.

    2014-02-01

    Fluorescence spectroscopy is an emerging tool used to differentiate normal and malignant tissue based on the emission spectral profile from endogenous fluorophores. The goal of this study is to estimate the concentration of fluorophores using autofluorescence spectroscopy and try to utilize its diagnostic potential on samples of clinical importance. Brain tumor tissues from patients who received craniotomy for the removal of astrocytoma, glioma, meningioma and schwannoma were utilized in this study. Fluorescence emissions of the formalin fixed samples were recorded at excitation wavelengths of 320 and 410 nm. The emission characteristics of fluorophores such as collagen, nicotinamide adenine dinucleotide (NADH), flavin adenine dinucleotide (FAD), phospholipids and porphyrins of tumor tissue and adjacent normal tissue were elicited. Exact tissue classification was carried out using the spectral intensity ratio (SIR) and multivariate principal component analysis-linear discriminant analysis (PCA-LDA). The diagnostic algorithm based on PCA-LDA provided better classification efficiency than SIR. Moreover, the spectral data based on an excitation wavelength of 410 nm are found to be more efficient in the classification than 320 nm excitation, using PCA-LDA. Better efficacy of PCA-LDA in tissue classification was further confirmed by the receiver operator characteristic (ROC) curve method. The results of this study establish the feasibility of using fluorescence spectroscopy based real time tools for the discrimination of brain tumors from the adjacent normal tissue during craniotomies, which at present faces a huge challenge.

  17. Absorption Spectroscopy, Emissive Properties, and Ultrafast Intersystem Crossing Processes in Transition Metal Complexes: TD-DFT and Spin-Orbit Coupling.

    PubMed

    Daniel, Chantal

    2016-01-01

    Absorption spectroscopy, emissive properties, and ultrafast intersystem crossing processes in transition metal complexes are discussed in the light of recent developments in time-dependent density functional theory (TD-DFT), spin-orbit coupling (SOC) effects, and non-adiabatic excited states dynamics. Methodological highlights focus on spin-orbit and vibronic couplings and on the recent strategies available for simulating ultra-fast intersystem crossings (ISC).The role of SOC in the absorption spectroscopy of third-row transition metal complexes is illustrated by two cases studies, namely Ir(III) phenyl pyridine and Re(I) carbonyl bipyridine complexes.The problem of luminescence decay in third-row transition metal complexes handled by TD-DFT linear and quadratic response theories including SOC is exemplified by three studies: (1) the phosphorescence of Ir(III) complexes from the lowest triplet state; (2) the emissive properties of square planar Pt(II) complexes with bidentate and terdentate ligands characterized by low-lying metal-to-ligand-charge-transfer (MLCT) and metal-centered (MC) states; and (3) the ultra-fast luminescence decay of Re(I) carbonyl bipyridine halides via low-lying singlet and triplet charge transfer states delocalized over the bipyridine and the halide ligands.Ultrafast ISC occurring in spin crossover [Fe (bpy)3]2+, in [Ru (bpy)3]2+, and [Re (Br)(CO)3(bpy] complexes are deciphered thanks to recent developments based on various approaches, namely non-radiative rate theory within the Condon approximation, non-adiabatic surface hopping molecular dynamics, and quantum wave packet dynamics propagation.

  18. Ballistic electron emission microscopy and spectroscopy of Au/GaAs interfaces

    NASA Technical Reports Server (NTRS)

    Kaiser, W. J.; Bell, L. D.; Hecht, M. H.; Grunthaner, F. J.

    1989-01-01

    This paper presents the first Schottky barrier results for the Au/GaAs(100) interface prepared completely in situ on GaAs grown by molecular-beam epitaxy. The resulting interface displays unexpected properties which can be interpreted in terms of enhanced electrode interdiffusion. In addition, the capability of molecular-beam epitaxy for in situ processing enables the stabilization of this interface against diffusion and allows the formation of a Au/GaAs system with nearly ideal properties. Newly developed ballistic electron spectroscopy and imaging techniques demonstrate that the heterogeneity present at the interface of Au/GaAs(100) fabricated on chemically treated GaAs substrates is removed.

  19. Terahertz spectroscopy of low-dimensional nanomaterials: nonlinear emission and ultrafast electrodynamics

    NASA Astrophysics Data System (ADS)

    Luo, Liang; Wang, Jigang

    2015-08-01

    Nonlinear and non-equilibrium properties of low-dimensional quantum materials are fundamental in nanoscale science yet transformative in nonlinear imaging/photonic technology today. These have been poorly addressed in many nano-materials despite of their well-established equilibrium optical and transport properties. The development of ultrafast terahertz (THz) sources and nonlinear spectroscopy tools facilitates understanding these issues and reveals a wide range of novel nonlinear and quantum phenomena that are not expected in bulk solids or atoms. In this paper, we discuss our recent discoveries in two model photonic and electronic nanostructures to solve two outstanding questions: (1) how to create nonlinear broadband terahertz emitters using deeply subwavelength nanoscale meta-atom resonators? (2) How to access one-dimensional (1D) dark excitons and their non-equilibrium correlated states in single-walled carbon nanotubes (SWMTs)?

  20. Terahertz Spectroscopy of Low-Dimensional Nanomaterials: Nonlinear Emission and Ultrafast Electrodynamics

    DOE PAGES

    Luo, Liang; Wang, Jigang

    2016-01-01

    Nonlinear and non-equilibrium properties of low-dimensional quantum materials are fundamental in nanoscale science yet transformative in nonlinear imaging/photonic technology today. These have been poorly addressed in many nano-materials despite of their well-established equilibrium optical and transport properties. The development of ultrafast terahertz (THz) sources and nonlinear spectroscopy tools facilitates understanding these issues and reveals a wide range of novel nonlinear and quantum phenomena that are not expected in bulk solids or atoms. In this paper, we discuss our recent discoveries in two model photonic and electronic nanostructures to solve two outstanding questions: (1) how to create nonlinear broadband terahertz emittersmore » using deeply subwavelength nanoscale meta-atom resonators? (2) How to access one-dimensional (1D) dark excitons and their non-equilibrium correlated states in single-walled carbon nanotubes (SWMTs)?« less

  1. Terahertz Spectroscopy of Low-Dimensional Nanomaterials: Nonlinear Emission and Ultrafast Electrodynamics

    SciTech Connect

    Luo, Liang; Wang, Jigang

    2016-01-01

    Nonlinear and non-equilibrium properties of low-dimensional quantum materials are fundamental in nanoscale science yet transformative in nonlinear imaging/photonic technology today. These have been poorly addressed in many nano-materials despite of their well-established equilibrium optical and transport properties. The development of ultrafast terahertz (THz) sources and nonlinear spectroscopy tools facilitates understanding these issues and reveals a wide range of novel nonlinear and quantum phenomena that are not expected in bulk solids or atoms. In this paper, we discuss our recent discoveries in two model photonic and electronic nanostructures to solve two outstanding questions: (1) how to create nonlinear broadband terahertz emitters using deeply subwavelength nanoscale meta-atom resonators? (2) How to access one-dimensional (1D) dark excitons and their non-equilibrium correlated states in single-walled carbon nanotubes (SWMTs)?

  2. Polarization Studies in Fast-Ion Beam Spectroscopy

    SciTech Connect

    Trabert, E

    2001-12-20

    In a historical review, the observations and the insight gained from polarization studies of fast ions interacting with solid targets are presented. These began with J. Macek's recognition of zero-field quantum beats in beam-foil spectroscopy as indicating alignment, and D.G. Ellis' density operator analysis that suggested the observability of orientation when using tilted foils. Lastly H. Winter's studies of the ion-beam surface interaction at grazing incidence yielded the means to produce a high degree of nuclear orientation in ion beams.

  3. Local structural study of doped-ceria by EXAFS spectroscopy

    NASA Astrophysics Data System (ADS)

    Shirbhate, S. C.; Yadav, A. K.; Acharya, S. A.; Sagdeo, A. P.; Jha, S. N.

    2016-05-01

    In the present work, Structural and Local structural study of Sm, Gd doped and Sm-Gd co-doped ceria system has been studied by Extended X-ray Absorption Fine Structure Spectroscopy (EXAFS). These ceria based systems are synthesized by hydrothermal synthesis route. Fluorite structure is confirmed by X-ray diffraction (XRD) and data is well fitted using Rietveld refinement by Full-Prof suite. Local structural changes in terms of coordination with surrounding, inter atomic distances and Debye Waller factor of nearest neighbor and next nearest neighbor has been discussed.

  4. Study of Chemical Carcinogens by Positron Annihilation Lifetime Spectroscopy

    NASA Astrophysics Data System (ADS)

    Pivtsaev, A. A.; Razov, V. I.; Karasev, A. O.

    2013-11-01

    We have used positron annihilation lifetime spectroscopy to study the carcinogens C21H20BrN3, C4H7Cl2O4P, CCl4, CHCl3, AlF3, C8H12N4O, C6H4Cl2 and the non-carcinogens H2O, AlCl3, CH2Cl2, C2H6OS. We have established a correlation between the annihilation characteristics of the studied compounds and their degree of carcinogenicity.

  5. Wavelength-resolved emission spectroscopy of the alkoxy and alkylthio radicals in a supersonic jet

    NASA Technical Reports Server (NTRS)

    Misra, Prabhakar; Zhu, Xinming; Hsueh, Ching-Yu; Kamal, Mohammed M.

    1993-01-01

    Wavelength-resolved emission spectra of methoxy (CH3O) and methylthio (CH3S) radicals have been obtained in a supersonic jet environment with a resolution of 0.3 nm by dispersing the total laser-induced fluorescence with a 0.6 m monochromator. A detailed analysis of the single vibronic level dispersed fluorescence spectra yields the following vibrational frequencies for CH3O in the X(2)E state; nu(sub 1 double prime) = 2953/cm, nu(sub 2 double prime) = 1375/cm, nu(sub 3 double prime) = 1062/cm, nu(sub 4 double prime) = 2869/cm, nu(sub 5 double prime) = 1528/cm and nu(sub 6 double prime) = 688/cm. A similar analysis of the wavelength-resolved emission spectra of CH3S provides the following ground state vibrational frequencies: nu(sub 2 double prime) = 1329/cm, nu(sub 3 double prime) = 739/cm and nu(sub 6 double prime) = 601/cm. An experimental uncertainty of 20/cm is estimated for the assigned frequencies.

  6. Field emission spectroscopy evidence for dual-barrier electron tunnelling in nanographite

    SciTech Connect

    Bandurin, D. A.; Kleshch, V. I.; Mingels, S.; Lützenkirchen-Hecht, D.; Müller, G.; Obraztsov, A. N.

    2015-06-08

    Nanocarbon films with upstanding flake-like graphite crystallites of nanometre thickness were fabricated by carbon condensation from a methane–hydrogen gas mixture activated by a direct-current discharge. The nanographite (NG) crystallites are composed of a few graphene layers. The adjacent atomic layers are connected partially at the edges of the crystallites to form strongly curved graphene structures. The extraordinary field emission (FE) properties were revealed for the NG films with an average current density of a few mA/cm{sup 2}, reproducibly obtained at a macroscopic applied field of about 1 V/μm. The integral FE current–voltage curves and electron spectra (FEES) of NG cathodes with multiple emitters were measured in a triode configuration. Most remarkably, above a threshold field, two peaks were revealed in FEES with different field-dependent shifts to lower energies. This behaviour evidences electron emission through a dual potential barrier, corresponding to carbon–carbon heterostructure formed as a result of the graphene bending.

  7. Investigation of PTFE transfer films by infrared emission spectroscopy and phase-locked ellipsometry

    NASA Technical Reports Server (NTRS)

    Lauer, James L.; Bunting, Bruce G.; Jones, William R., Jr.

    1987-01-01

    When a PTFE sheet was rubbed unidirectionally over a smooth surface of stainless steel an essentially monomolecular transfer film was formed. By ellipsometric and emission infrared spectroscopic techniques it was shown that the film was 10 to 15 A thick and birefringent. From the intensity differences of infrared bands obtained with a polarizer passing radiation polarized in mutually perpendicular planes, it was possible to deduce transfer film orientation with the direction of rubbing. After standing in air for several weeks the transfer films apparently increased in thickness by as much as threefold. At the same time both the index of refraction and the absorption index decreased. Examination of the surfaces by optical and electron microscopies showed that the films had become porous and flaky. These observations were consistent with previous tribological measurements. The coefficients of friction decreased with the formation of the transfer film but increased again as the film developed breaks. The applicability of the ellipsometric and polarized infrared emission techniques to the identification of monomolecular tribological transfer films of polymers such as PTFE has been demonstrated.

  8. Investigation of PTFE transfer films by infrared emission spectroscopy and phase-locked ellipsometry

    NASA Technical Reports Server (NTRS)

    Lauer, James L.; Bunting, Bruce G.; Jones, William R., Jr.

    1988-01-01

    When a PTFE sheet was rubbed unidirectionally over a smooth surface of stainless steel an essentially monomolecular transfer film was formed. by ellipsometric and emission infrared spectroscopic techniques it was shown that the film was 10 to 15 A thick and birefringent. From the intensity differences of infrared bands obtained with a polarizer passing radiation polarized in mutually perpendicular planes, it was possible to deduce transfer film orientation with the direction of rubbing. After standing in air for several weeks the transfer films apparently increased in thickness by as much as threefold. At the same time both the index of refraction and the absorption index decreased. Examination of the surfaces by optical and electron microscopies showed that the films had become porous and flaky. These observations were consistent with previous tribological measurements. The coefficients of friction decreased with the formation of the transfer film but increased again as the film developed breaks. The applicability of the ellipsometric and polarized infrared emission techniques to the identification of monomolecular tribological transfer films of polymers such as PTFE has been demonstrated.

  9. VUV emission spectroscopy diagnostics of a 14 GHz ECR negative hydrogen ion source

    SciTech Connect

    Tamura, R. Ichikawa, T.; Kasuya, T.; Wada, M.; Nishiura, M.; Shimozuma, T.

    2015-04-08

    Vacuum Ultra Violet(VUV) emission from a 4 cm diameter 2 cm long compact ion source excited by 14 GHz microwave has been investigated. Intensity ratio of band spectrum emission near Ly-α to Ly-α line spectrum is determined from the measured spectrum. which shows preferential excitation of molecules near the entrance of microwave input power. The ratio does not depend strongly upon pressure nor the input microwave power when the intensity is integrated over the volume of the plasma. The spatial distribution of the spectrum intensity ratio exhibits concentrations near microwave inlet and the opposite side where the microwave matching structure is located. The ratio at these peripheral regions is about two times as high as that of the central region. The ratio increased in proportion to the ion source pressure up to about 3.0 Pa, indicating efficient production of high energy electrons by ECR up to this pressure.

  10. A novel field emission microscopy method to study field emission characteristics of freestanding carbon nanotube array.

    PubMed

    Li, Yunhan; Sun, Yonghai; Jaffray, David; Yeow, John T W

    2017-02-17

    Field emission (FE) uniformity and mechanism of emitter failure of freestanding carbon nanotube (CNT) arrays have not been well studied due to the difficulty of observing and quantifying FE performance of each emitter in CNT arrays. Herein a field emission microscopy (FEM) method based on Poly(methyl methacrylate) (PMMA) thin film is proposed to study the FE uniformity and CNT emitter failure of freestanding CNT arrays. FE uniformity of freestanding CNT arrays and different levels of FE current contributions from each emitter in the arrays are recorded and visualized. FEM patterns on the PMMA thin film contain the details of the CNT emitter tip shape and whether multiple CNT emitters occurring at an emission site. Observation of real-time FE performance and CNT emitter failure process in freestanding CNT arrays are successfully achieved using a microscopic camera. High emission currents through CNT emitters causes joule heating and light emission followed by an explosion of the CNTs. The proposed approach is capable of resolving the major challenge of building the relationship between FE performances and CNT morphologies, which can significantly facilitate the study of FE non-uniformity and emitter failure mechanism and the development of stable and reliable FE devices in practical applications.

  11. A novel field emission microscopy method to study field emission characteristics of freestanding carbon nanotube arrays

    NASA Astrophysics Data System (ADS)

    Li, Yunhan; Sun, Yonghai; Jaffray, David A.; Yeow, John T. W.

    2017-04-01

    Field emission (FE) uniformity and the mechanism of emitter failure of freestanding carbon nanotube (CNT) arrays have not been well studied due to the difficulty of observing and quantifying FE performance of each emitter in CNT arrays. Herein a field emission microscopy (FEM) method based on poly(methyl methacrylate) (PMMA) thin film is proposed to study the FE uniformity and CNT emitter failure of freestanding CNT arrays. FE uniformity of freestanding CNT arrays and different levels of FE current contributions from each emitter in the arrays are recorded and visualized. FEM patterns on the PMMA thin film contain the details of the CNT emitter tip shape and whether multiple CNT emitters occur at an emission site. Observation of real-time FE performance and the CNT emitter failure process in freestanding CNT arrays are successfully achieved using a microscopic camera. High emission currents through CNT emitters causes Joule heating and light emission followed by an explosion of the CNTs. The proposed approach is capable of resolving the major challenge of building the relationship between FE performance and CNT morphologies, which can significantly facilitate the study of FE non-uniformity, the emitter failure mechanism and the development of stable and reliable FE devices in practical applications.

  12. Investigation of local thermodynamic equilibrium of laser induced Al2O3-TiC plasma in argon by spatially resolved optical emission spectroscopy

    NASA Astrophysics Data System (ADS)

    Alnama, K.; Alkhawwam, A.; Jazmati, A. K.

    2016-06-01

    Plasma plume of Al2O3-TiC is generated by third harmonic Q-switched Nd:YAG nanosecond laser. It is characterized using Optical Emission Spectroscopy (OES) at different argon background gas pressures 10, 102, 103, 104 and 105 Pa. Spatial evolution of excitation and ionic temperatures is deduced from spectral data analysis. Temporal evolution of Ti I emission originated from different energy states is probed. The correlation between the temporal behavior and the spatial temperature evolution are investigated under LTE condition for the possibility to use the temporal profile of Ti I emission as an indicator for LTE validity in the plasma.

  13. Resonant X-ray emission spectroscopy reveals d-d ligand-field states involved in the self-assembly of a square-planar platinum complex.

    PubMed

    Garino, Claudio; Gallo, Erik; Smolentsev, Nikolay; Glatzel, Pieter; Gobetto, Roberto; Lamberti, Carlo; Sadler, Peter J; Salassa, Luca

    2012-11-28

    Resonant X-ray Emission Spectroscopy (RXES) is used to characterize the ligand field states of the prototypic self-assembled square-planar complex, [Pt(tpy)Cl]Cl (tpy=2,2':6',2''-terpyridine), and determine the effect of weak metal-metal and π-π interactions on their energy.

  14. Optically Detected Magnetic Resonance and Thermal Activation Spectroscopy Study of Organic Semiconductors

    SciTech Connect

    Kim, Chang-Hwan

    2003-01-01

    Organic electronic materials are a new class of emerging materials. Organic light emitting devices (OLEDs) are the most promising candidates for future flat panel display technologies. The photophysical characterization is the basic research step one must follow to understand this new class of materials and devices. The light emission properties are closely related to the transport properties of these materials. The objective of this dissertation is to probe the relation between transport and photophysical properties of organic semiconductors. The transport characteristics were evaluated by using thermally stimulated current and thermally stimulated luminescence techniques. The photoluminescence detected magnetic resonance and photoluminescence quantum yield studies provide valuable photophysical information on this class of materials. OLEDs are already in the market. However, detailed studies on the degradation mechanisms are still lacking. Since both optically detected magnetic resonance and thermal activation spectroscopy probe long-lived defect-related states in organic semiconductors, the combined study generates new insight on the OLED operation and degradation mechanisms.

  15. Chemical analysis of impurity boron atoms in diamond using soft X-ray emission spectroscopy.

    PubMed

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

    2008-07-01

    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.

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

    SciTech Connect

    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.

  17. Exoplanet atmosphere. Thermal structure of an exoplanet atmosphere from phase-resolved emission spectroscopy.

    PubMed

    Stevenson, Kevin B; Désert, Jean-Michel; Line, Michael R; Bean, Jacob L; Fortney, Jonathan J; Showman, Adam P; Kataria, Tiffany; Kreidberg, Laura; McCullough, Peter R; Henry, Gregory W; Charbonneau, David; Burrows, Adam; Seager, Sara; Madhusudhan, Nikku; Williamson, Michael H; Homeier, Derek

    2014-11-14

    Exoplanets that orbit close to their host stars are much more highly irradiated than their solar system counterparts. Understanding the thermal structures and appearances of these planets requires investigating how their atmospheres respond to such extreme stellar forcing. We present spectroscopic thermal emission measurements as a function of orbital phase ("phase-curve observations") for the highly irradiated exoplanet WASP-43b spanning three full planet rotations using the Hubble Space Telescope. With these data, we construct a map of the planet's atmospheric thermal structure, from which we find large day-night temperature variations at all measured altitudes and a monotonically decreasing temperature with pressure at all longitudes. We also derive a Bond albedo of 0.18(-0.12)(+0.07) and an altitude dependence in the hot-spot offset relative to the substellar point.

  18. Development of Advanced Electrochemical Emission Spectroscopy for Monitoring Corrosion in Simulated DOE Liquid Waste

    SciTech Connect

    Macdonald, Digby; Liu, Jun; Liu, Sue; Al-Rifaie, Mohammed; Sikora; Elzbieta

    2000-06-01

    The principal goals of this project are to develop advanced electrochemical emission spectroscopic (EES) methods for monitoring the corrosion of carbon steel in simulated DOE liquid waste and to develop a better understanding of the mechanisms of the corrosion of metals (e.g. iron, nickel, and chromium) and alloys (carbon steel, low alloy steels, stainless steels) in thes e environments. During the first two years of this project, significant advances have been made in developing a better understanding of the corrosion of iron in aqueous solutions as a function of pH, on developing a better understanding of the growth of passive films on metal surfaces, and on developing EES techniques for corrosion monitoring. This report summarizes work on beginning the third year of the 3-year project.

  19. Development of a Reference Database for Particle-Induced Gamma-ray Emission spectroscopy

    NASA Astrophysics Data System (ADS)

    Dimitriou, P.; Becker, H.-W.; Bogdanović-Radović, I.; Chiari, M.; Goncharov, A.; Jesus, A. P.; Kakuee, O.; Kiss, A. Z.; Lagoyannis, A.; Räisänen, J.; Strivay, D.; Zucchiatti, A.

    2016-03-01

    Particle-Induced Gamma-ray Emission (PIGE) is a powerful analytical technique that exploits the interactions of rapid charged particles with nuclei located near a sample surface to determine the composition and structure of the surface regions of solids by measurement of characteristic prompt γ rays. The potential for depth profiling of this technique has long been recognized, however, the implementation has been limited owing to insufficient knowledge of the physical data and lack of suitable user-friendly computer codes for the applications. Although a considerable body of published data exists in the nuclear physics literature for nuclear reaction cross sections with γ rays in the exit channel, there is no up-to-date, comprehensive compilation specifically dedicated to IBA applications. A number of PIGE cross-section data had already been uploaded to the Ion Beam Analysis Nuclear Data Library (IBANDL)

  20. Vibronic emission spectroscopy of benzyl-type radicals: Jet-cooled 2-fluoro-5-chlorobenzyl radical

    NASA Astrophysics Data System (ADS)

    Yoon, Young Wook; Chae, Sang Youl; Lee, Sang Kuk

    2014-07-01

    We produced the vibronically excited but jet-cooled 2-fluoro-5-chlorobenzyl radical by corona discharge of precursor 2-fluoro-5-chlorotoluene with a large amount of carrier gas He using a pinhole-type glass nozzle in a technique of corona excited supersonic jet expansion. The vibronic emission spectrum was recorded using a long-path double monochromator in the visible region. From an analysis of the spectrum, we determined the electronic energy of the D1 → D0 transition and vibrational mode frequencies in the ground electronic state of the 2-fluoro-5-chlorobenzyl radical for the first time. In addition, substituent effect on electronic transition energy was discussed for substituents on the benzene ring.

  1. [Investigation of a jet operated in atmospheric pressure argon by optical emission spectroscopy].

    PubMed

    Li, Xue-chen; Bao, Wen-ting; Jia, Peng-ying; Di, Cong; Yuan, Ning

    2014-06-01

    A uniform plasma plume was generated in a coaxial dielectric barrier discharge jet through blowing argon into the ambient air at atmospheric pressure. The plasma plume was uniform along the direction of the gas flow. The length of the plasma plume was investigated as a function of the peak voltage, the driving frequency and the gas flow rate. It was found that with increasing the gas flow rate, the plume length increases when the flow rate is lower than 4 L x min(-1), and decreases when it is higher than 4 L x mic(-1). Under constant gas flow rate, the length of the plasma plume increases with the increase in the peak value of the applied voltage and the driving frequency. According to the discharge theory and based on the analysis of the turbulence and the advection, a qualitative explanation was given for the variance of plume length as functions of the experimental parameters. Results also show that there is a discharge pulse for the plasma plume in every positive half cycle, while there is no pulse in negative half cycle. The coaxial dielectric barrier discharge shows two pulses in every positive half cycle and a pulse in every negative half cycle. Analyzing these experimental phenomena mentioned above, a formation mechanism of the plasma plume was proposed. The optical emission spectra were obtained for both the coaxial dielectric barrier discharge and the plasma plume. There was no apparent difference except that some emission lines from reactive species such as OH and N2 were found in the plasma plume. Using the first negative band of, the rational temperature of the plasma plume was measured. Results show that the rational temperature of the plasma plume decreases away from the jet nozzle, and increases with increasing the peak value of the applied voltage.

  2. Parametric Study of Variable Emissivity Radiator Surfaces

    NASA Technical Reports Server (NTRS)

    Grob, Lisa M.; Swanson, Theodore D.

    2000-01-01

    The goal of spacecraft thermal design is to accommodate a high function satellite in a low weight and real estate package. The extreme environments that the satellite is exposed during its orbit are handled using passive and active control techniques. Heritage passive heat rejection designs are sized for the hot conditions and augmented for the cold end with heaters. The active heat rejection designs to date are heavy, expensive and/or complex. Incorporating an active radiator into the design that is lighter, cheaper and more simplistic will allow designers to meet the previously stated goal of thermal spacecraft design Varying the radiator's surface properties without changing the radiating area (as with VCHP), or changing the radiators' views (traditional louvers) is the objective of the variable emissivity (vary-e) radiator technologies. A parametric evaluation of the thermal performance of three such technologies is documented in this paper. Comparisons of the Micro-Electromechanical Systems (MEMS), Electrochromics, and Electrophoretics radiators to conventional radiators, both passive and active are quantified herein. With some noted limitations, the vary-e radiator surfaces provide significant advantages over traditional radiators and a promising alternative design technique for future spacecraft thermal systems.

  3. Study of air emissions related to aircraft deicing

    SciTech Connect

    Zarubiak, D.C.Z.; DeToro, J.A.; Menon, R.P.

    1997-12-31

    This paper outlines the results of a study that was conducted by Trinity Consultants Incorporated (Trinity) to estimate the airborne emissions of glycol from Type 1 Deicer fluid and potential exposure of ground personnel during routine deicing of aircraft. The study involved the experimental measurement of Type 1 Deicer fluid vapor emissions by Southern Research Institute (SRI, Research Triangle Park, NC). An open path Fourier Transform Infrared (FTIR) spectroscopic technique developed by SRI was used during a simulated airplane deicing event. The emissions measurement data are analyzed to obtain appropriate emission rates for an atmospheric dispersion modeling analysis. The modeled gaseous Type 1 Deicer fluid concentrations are determined from calculated emission rates and selected meteorological conditions. A propylene glycol (PG)-based Type 1 Deicer fluid was used. In order to examine the effects of the assumptions that are made for the development of the emission quantification and dispersion modeling methodologies, various scenarios are evaluated. A parametric analysis evaluates the effect of variations in the following parameters on the results of the study: glycol concentrations in deicing fluids, error limits of emission measurements, emission source heights, evaporation rate for various wind speeds, wind directions over typical physical layouts, and background (ambient) Type 1 Deicer fluid concentrations. The emissions for an EG based Type 1 Deicing fluid are expected to be between 80 and 85% of the reported data. In general, the model shows the region of maximum concentrations is located between 20 and 50 meters downwind from the trailing edge of the wing. This range is consistent with experimental findings. Depending on the specific modeled scenarios, maximum glycol concentrations are found to generally range between 50 and 500 milligrams per cubic meter.

  4. Quantifying aflatoxins in peanuts using fluorescence spectroscopy coupled with multi-way methods: Resurrecting second-order advantage in excitation-emission matrices with rank overlap problem.

    PubMed

    Sajjadi, S Maryam; Abdollahi, Hamid; Rahmanian, Reza; Bagheri, Leila

    2016-03-05

    A rapid, simple and inexpensive method using fluorescence spectroscopy coupled with multi-way methods for the determination of aflatoxins B1 and B2 in peanuts has been developed. In this method, aflatoxins are extracted with a mixture of water and methanol (90:10), and then monitored by fluorescence spectroscopy producing EEMs. Although the combination of EEMs and multi-way methods is commonly used to determine analytes in complex chemical systems with unknown interference(s), rank overlap problem in excitation and emission profiles may restrain the application of this strategy. If there is rank overlap in one mode, there are several three-way algorithms such as PARAFAC under some constraints that can resolve this kind of data successfully. However, the analysis of EEM data is impossible when some species have rank overlap in both modes because the information of the data matrix is equivalent to a zero-order data for that species, which is the case in our study. Aflatoxins B1 and B2 have the same shape of spectral profiles in both excitation and emission modes and we propose creating a third order data for each sample using solvent as a new additional selectivity mode. This third order data, in turn, converted to the second order data by augmentation, a fact which resurrects the second order advantage in original EEMs. The three-way data is constructed by stacking augmented data in the third way, and then analyzed by two powerful second order calibration methods (BLLS-RBL and PARAFAC) to quantify the analytes in four kinds of peanut samples. The results of both methods are in good agreement and reasonable recoveries are obtained.

  5. Quantifying aflatoxins in peanuts using fluorescence spectroscopy coupled with multi-way methods: Resurrecting second-order advantage in excitation-emission matrices with rank overlap problem

    NASA Astrophysics Data System (ADS)

    Sajjadi, S. Maryam; Abdollahi, Hamid; Rahmanian, Reza; Bagheri, Leila

    2016-03-01

    A rapid, simple and inexpensive method using fluorescence spectroscopy coupled with multi-way methods for the determination of aflatoxins B1 and B2 in peanuts has been developed. In this method, aflatoxins are extracted with a mixture of water and methanol (90:10), and then monitored by fluorescence spectroscopy producing EEMs. Although the combination of EEMs and multi-way methods is commonly used to determine analytes in complex chemical systems with unknown interference(s), rank overlap problem in excitation and emission profiles may restrain the application of this strategy. If there is rank overlap in one mode, there are several three-way algorithms such as PARAFAC under some constraints that can resolve this kind of data successfully. However, the analysis of EEM data is impossible when some species have rank overlap in both modes because the information of the data matrix is equivalent to a zero-order data for that species, which is the case in our study. Aflatoxins B1 and B2 have the same shape of spectral profiles in both excitation and emission modes and we propose creating a third order data for each sample using solvent as a new additional selectivity mode. This third order data, in turn, converted to the second order data by augmentation, a fact which resurrects the second order advantage in original EEMs. The three-way data is constructed by stacking augmented data in the third way, and then analyzed by two powerful second order calibration methods (BLLS-RBL and PARAFAC) to quantify the analytes in four kinds of peanut samples. The results of both methods are in good agreement and reasonable recoveries are obtained.

  6. Looking for the broad emission lines in AGN2 with deep NIR spectroscopy and the measure of the mass of Intermediate Mass BH

    NASA Astrophysics Data System (ADS)

    Onori, Francesca; La Franca, Fabio; Ricci, Federica

    According to the current models of galaxy evolution, in a hierarchical cosmology low mass Black Holes (10 (4) - 10 (7) M_⊙) at low redshift contain clues about the formation of the first Black Holes and Galaxies. Moreover, as they extend the dynamic range of the BH-mass/galaxy scaling relations to extreme values, they could be very useful in constraining the AGN/Galaxy co-evolutionary models. In the past years, in the framework of the verification of the AGN unified model, there have been several attempts to detect faint broad emission lines in type 2 AGN with both NIR and polarised spectroscopy. We here present the new results from a systematic study, performed using deep NIR (VLT and LBT) spectroscopy, of about 50 AGN2, drawn from the complete SWIFT/BAT 22-month had X-ray selected sample. A new virial relation able to measure the BH mass using the broad component of the Paschenbeta line will be also presented. Thanks to the above relation we have been able to directly measure, when the BLR has been detected, the BH mass of type 2 AGNs, finding that AGN2 show on average lower masses than the AGN1 population. The implications to the AGN unified model and AGN/galaxy co-evolution scenarios will be discussed.

  7. Infrared and infrared emission spectroscopic study of typical Chinese kaolinite and halloysite.

    PubMed

    Cheng, Hongfei; Frost, Ray L; Yang, Jing; Liu, Qinfu; He, Junkai

    2010-12-01

    The structure and thermal stability between typical Chinese kaolinite and halloysite were analysed by X-ray diffraction (XRD), infrared spectroscopy, infrared emission spectroscopy (IES) and Raman spectroscopy. Infrared emission spectroscopy over the temperature range of 300-700°C has been used to characterise the thermal decomposition of both kaolinite and halloysite. Halloysite is characterised by two bands in the water bending region at 1629 and 1648 cm(-1), attributed to structural water and coordinated water in the interlayer. Well defined hydroxyl stretching bands at around 3695, 3679, 3652 and 3625 cm(-1) are observed for both kaolinite and halloysite. The 550°C infrared emission spectrum of halloysite is similar to that of kaolinite in 650-1350 cm(-1) spectral region. The infrared emission spectra of halloysite were found to be considerably different to that of kaolinite at lower temperatures. These differences are attributed to the fundamental difference in the structure of the two minerals.

  8. Using neural networks to predict incinerator emissions: A case study

    SciTech Connect

    Heitz, M.W.; George, B.; Welp, J.E.

    1997-12-31

    This paper presents a case study applying a neural network to predict incinerator emissions. A neural network is a program which is used to develop relationships between process operating variables (input data) and emissions (output data). Recent Federal 503 Regulations for Sewage Sludge Incinerators have required the installation of total hydrocarbon (THC) or carbon monoxide (CO) continuous emission monitoring systems (CEMS) to assure emission compliance. These systems are expensive to install, operate, and maintain. An investigation was performed to develop a simulation model using an artificial intelligence program with the goal of improved operations and reduced air emissions. This paper presents methods used for data collection, data preprocessing, and network training, as well as the architecture and weights of the final network. The network application has improved incinerator operations and limited emissions by determining acceptable ranges of operating variables. Neural networks have been found to accurately predict incinerator emissions. Their use would reduce the burden of high monitoring and compliance costs associated with CEMS. Neural networks may be applied to other environmental monitoring and control processes.

  9. Global warming and global dioxide emission: An empirical study

    SciTech Connect

    Linyan Sun; Wang, M.

    1996-04-01

    In this paper, the dynamic relationship between global surface temperature (global warming) and global carbon dioxide emission (CO{sub 2}) is modelled and analyzed by causality and spectral analysis in the time domain and frequency domain, respectively. Historical data of global CO{sub 2} emission and global surface temperature anomalies over 129 years from 1860-1988 are used in this study. The causal relationship between the two phenomena is first examined using the Sim and Granger causality test in the time domain after the data series are filtered by ARIMA models. The Granger causal relationship is further scrutinized and confirmed by cross-spectral and multichannel spectral analysis in the frequency domain. The evidence found from both analyses proves that there is a positive causal relationship between the two variables. The time domain analysis suggests that Granger causality exists between global surface temperature and global CO{sub 2} emission. Further, CO{sub 2} emission causes the change in temperature. The conclusions are further confirmed by the frequency domain analysis, which indicates that the increase in CO{sub 2} emission causes climate warming because a high coherence exists between the two variables. Furthermore, it is proved that climate changes happen after an increase in CO{sub 2} emission, which confirms that the increase in CO{sub 2} emission does cause global warming. 27 refs., 10 figs., 5 tabs.

  10. Determining the Products and Mechanism of the C2Cl3+O2 Reaction by Time-Resolved FTIR Emission Spectroscopy

    NASA Astrophysics Data System (ADS)

    Su, Hongmei; Xiang, Tiancheng; Zhao, Shaolei; Shi, Congyun

    2006-03-01

    The reaction products and mechanism of the C2Cl3 radical with O2 have been studied by time-resolved FTIR emission spectroscopy. The chlorinated vinyl radical, C2Cl3, was generated by 248 nm photolysis of a C2Cl4 precursor. Vibrationally excited CO, CO2 and ClCO products were observed. The time evolution of the emission intensity shows that CO2 and ClCO are primary reaction products. In contrast, CO emission does not decay until ms time scale indicating that CO products are due to secondary reactions, most likely, the further dissociation of ClCO. Two primary reaction channels are identified: C2Cl3 + O2 ♢ CO2 + CCl3 ♢ ClCO + COCl2 When reacting with O2, the observed products and channels of the chlorinated vinyl radical, C2Cl3, turned out to be very similar to its counterpart, vinyl radical C2H3. Morokuma's DFT study^[1] of the reaction C2H3+O2 shows that the main reaction path proceeds through a three-membered CCO ring adduct. The question is, does C2Cl3 go through the same reaction path as C2H3? Does the substitution of H atom by heavier Cl atom make any difference in regard to the reaction mechanism? Further investigation combining ab initio calculation is under way. [1] A.M.Mabel, E.W.G.Diau, M.C.Lin, and K.Morokuma, J.Am.Chem.Soc. 118, 9759 (1996)

  11. Infrared (1-12 μm) atomic and molecular emission signatures from energetic materials using laser-induced breakdown spectroscopy

    NASA Astrophysics Data System (ADS)

    Kumi Barimah, E.; Hömmerich, U.; Brown, E.; Yang, C. S.-C.; Trivedi, S. B.; Jin, F.; Wijewarnasuriya, P. S.; Samuels, A. C.; Snyder, A. P.

    2013-05-01

    Laser-induced breakdown spectroscopy (LIBS) is a powerful analytical technique to detect the elemental composition of solids, liquids, and gases in real time. For example, recent advances in UV-VIS LIBS have shown great promise for applications in chemical, biological, and explosive sensing. The extension of conventional UVVIS LIBS to the near-IR (NIR), mid-IR (MIR) and long wave infrared (LWIR) regions (~1-12 μm) offers the potential to provide additional information due to IR atomic and molecular signatures. In this work, a Q-switched Nd: YAG laser operating at 1064 nm was employed as the excitation source and focused onto several chlorate and nitrate compounds including KClO3, NaClO3, KNO3, and NaNO3 to produce intense plasma at the target surface. IR LIBS studies on background air, KCl , and NaCl were also included for comparison. All potassium and sodium containing samples revealed narrow-band, atomic-like emissions assigned to transitions of neutral alkali-metal atoms in accordance with the NIST atomic spectra database. In addition, first evidence of broad-band molecular LIBS signatures from chlorate and nitrate compounds were observed at ~10 μm and ~7.3 μm, respectively. The observed molecular emissions showed strong correlation with FTIR absorption spectra of the investigated materials.

  12. Time-resolved Fourier-transform infrared emission spectroscopy of Ag in the (1300-3600)-cm-1 region: Transitions involving f and g states and oscillator strengths

    NASA Astrophysics Data System (ADS)

    Civiš, S.; Matulková, I.; Cihelka, J.; Kubelik, P.; Kawaguchi, K.; Chernov, V. E.

    2010-08-01

    We report on a study of the emission spectra of Ag vapor in a vacuum (10-2 Torr) formed in ablation of an Ag metal target by a high-repetition rate (1.0 kHz) pulsed nanosecond ArF laser (λ=193 nm, output energy of 15 mJ). The time-resolved infrared emission spectrum of Ag was recorded in the 1300- to 3600-cm-1 spectral region using the Fourier transform infrared spectroscopy technique with a resolution of 0.02 cm-1. The time profiles of the measured lines have maxima at 5-6 μs after a laser shot and display nonexponential decay with a decay time of 3-7 μs. The lines reported here are given with an uncertainty of 0.0005-0.016 cm-1. The line classification is performed using relative line strengths expressed in terms of transition dipole matrix elements calculated with the help of the Fues model potential; these calculations show agreement with the large experimental and calculated data sets available in the literature. In addition to these data we also calculate transition probabilities and line and oscillator strengths for a number of transitions in the 1300- to 5000-cm-1 range between (4d10)nlj states of Ag.

  13. Fluorescence spectroscopy to study dissolved organic matter interactions with agrochemicals applied in Swiss vineyards.

    PubMed

    Daouk, Silwan; Frege, Carla; Blanc, Nicolas; Mounier, Stéphane; Redon, Roland; Merdy, Patricia; Lucas, Yves; Pfeifer, Hans-Rudolf

    2015-06-01

    UV/Vis fluorescence spectroscopy was used to study the possible interactions of dissolved organic matter (DOM) with the herbicide glyphosate and copper-based fungicide used in vineyards. The study focused on the role of DOM in the transport of these micropollutants from parcels to surface waters (river, lake). Soil solution and river water samples were collected in the Lavaux vineyard area, western Switzerland. Their fluorescence excitation emission matrices (EEM) were decomposed using parallel factor (PARAFAC) analysis, and compared to their content in glyphosate and copper. PARAFAC analysis of EEM of both types of samples showed the contribution of protein-like and humic-like fluorophores. In soil water samples, complexes between fulvic-like and humic-like fluorophores of DOM, copper, and glyphosate were likely formed. In surface water, DOM-copper and glyphosate-copper interactions were observed, but not between glyphosate and DOM.

  14. Source fingerprint monitoring of air pollutants from petrochemical industry and the determination of their annual emission flux using open path Fourier transform infrared spectroscopy

    SciTech Connect

    Yih-Shiaw Huang; Shih-Yi Chang; Tai-Ly Tso

    1996-12-31

    Toxic air pollutants were investigated in several petrochemical industrial park in Taiwan using a movable open-path Fourier-transform infrared spectroscopy (FTIR). The results show the qualitative and quantitative analysis of emission gases from plants, and also provide the emission rates of various compounds. More than twenty compounds under usual operation were found from these industrial park. The concentration variation with time could be correlated exactly with the distances from the emission source along the wind direction. This means that by changing the measuring points the source of emission could be unambiguously identified. The point, area and line source (PAL) plume dispersion model has been applied to estimate the emission rate of either a point or an area source. The local atmospheric stability was determined by releasing an SF{sub 6} tracer. The origin of errors came mainly from the uncertainty of the source configuration and the variation of the meteorological condition. Through continuous measurement using a portable open-path Fourier transform infrared (POP-FTIR) spectrometer, the maximum value of the emission rate and the annual amount of emission could be derived. The emission rate of the measured toxic gases was derived by the model technique, and the results show that the emission amount is on the order of ten to hundred tons per year.

  15. Fourier transform emission spectroscopy of the near infrared transitions of CeS

    NASA Astrophysics Data System (ADS)

    Ram, R. S.; Bernath, P. F.

    2014-05-01

    The emission spectra of CeS have been investigated at high resolution with a Fourier transform spectrometer. Several bands observed in the 4000-9000 cm-1 region have been classified into nine transitions having five different lower states, X1(3), X2(⩾ 2), X3(⩾ 2), X4(⩾ 3) and X5(0) based on Ω doubling and relative branch intensities. Out of these, the [7.54] (4) → X1(3) transition consisting of 0-1, 1-2, 0-0, 1-1, 1-0 and 2-1 bands is strongest in intensity. A rotational analysis of these bands provides equilibrium spectroscopic constants: ωe = 461.3947(14) cm-1, ωexe = 1.00095(65) cm-1, Be = 0.118782207(15) cm-1, αe = 0.000341453(14) cm-1 and re = 2.33522875(15) Å for the lower X1(Ω = 3) state. The [8.78] (⩾3) → X2(⩾2) transition, for which 0-0 and 0-1 bands were rotationally analyzed, provides ΔG½ = 458.87411(88) cm-1, Be = 0.1187649(31) cm-1, αe = 0.0003401(37) cm-1 and re = 2.335399(31) Å for the X2(Ω ⩾ 2) lower state.

  16. On the Automated and Objective Detection of Emission Lines in Faint-Object Spectroscopy

    NASA Astrophysics Data System (ADS)

    Hong, Sungryong; Dey, Arjun; Prescott, Moire K. M.

    2014-11-01

    Modern spectroscopic surveys produce large spectroscopic databases, generally with sizes well beyond the scope of manual investigation. The need arises, therefore, for an automated line detection method with objective indicators for detection significance. In this paper, we present an automated and objective method for emission line detection in spectroscopic surveys and apply this technique to 1574 spectra, obtained with the Hectospec spectrograph on the MMT Observatory (MMTO), to detect Lyman alpha emitters near z ~ 2.7. The basic idea is to generate on-source (signal plus noise) and off-source (noise only) mock observations using Monte Carlo simulations, and calculate completeness and reliability values, (C, R), for each simulated signal. By comparing the detections from real data with the Monte Carlo results, we assign the completeness and reliability values to each real detection. From 1574 spectra, we obtain 881 raw detections and, by removing low reliability detections, we finalize 649 detections from an automated pipeline. Most of high completeness and reliability detections, (C, R) ~ (1.0, 1.0), are robust detections when visually inspected; the low C and R detections are also marginal on visual inspection. This method at detecting faint sources is dependent on the accuracy of the sky subtraction.

  17. Balloon measurements of stratospheric HCl and HF by far infrared emission spectroscopy

    NASA Technical Reports Server (NTRS)

    Shibasaki, Kazuo; Chance, Kelly V.; Johnson, David G.; Jucks, Kenneth W.; Traub, Wesley A.

    1994-01-01

    We have analyzed atmospheric thermal emission spectra obtained with the balloon-borne FIRS-2 far infrared Fourier transform spectrometer during balloon flights from Palestine, Texas on May 12-13, 1988 and from Fort Sumner, New Mexico on September 26-27, 1989 and on July 4-5, 1990. Seven and two pure rotational transition lines in 100-205 cm(exp -1) range are analyzed for deriving vertical profiles of stratospheric HCl and HF, respectively. We obtain both the daytime and nighttime average vertical profiles from 15 to 50 km. We compare these profiles with the ones obtained in June, 1983 with the first version of FIRS spectrometer during the Balloon Intercomparison Campaign (BIC-2). BIC-2 results were revised to be consistent with the present analysis which uses the latest spectral parameters. According to our comparison results no increase is recognized for HCl but about 3 percent per year increase for HF from 1983 to 1990, assuming a linear trend. These annual increase rates are smaller than those reported by other groups. Recently Rinsland et al. (1991) and Wallace and Livingston (1991) reported long term behavior of total HCl and HF observed on Kit Peak between 1977 and 1990. As Kit Peak is located near both balloon launching sites, Palestine and Fort Sumner, we think our results are favorably comparable with theirs. Comparison results with ours and ground-based measurements will be presented and discussed.

  18. Emission spectroscopy of an atmospheric pressure plasma jet operated with air at low frequency

    NASA Astrophysics Data System (ADS)

    Giuliani, L.; Gallego, J. L.; Minotti, F.; Kelly, H.; Grondona, D.

    2015-03-01

    Low-temperature, high-pressure plasma jets have an extensive use in plasma biology and plasma medicine, such as pathogen deactivation, wound disinfection, stopping of bleeding without damage of healthy tissue, acceleration of wound healing, control of bio-film proliferation, etc. In this work, a spectroscopic characterization of a typical plasma jet, operated in air at atmospheric pressure, is reported. Within the spectrum of wavelengths from 200 to 450 nm all remarkable emissions of N2 were monitored. Spectra of the N2 2nd positive system (C3Πu-B3Πg) emitted in air are the most convenient for plasma diagnostics, since they enable to determine electronic Te, rotational Tr and vibrational Tv temperatures by fitting the experimental spectra with the simulated ones. We used SPECAIR software for spectral simulation and obtained the best fit with all these temperatures about 3500K. The conclusion that all temperatures are equal, and its relatively high value, is consistent with the results of a previous work, where it was found that the experimentally determined electrical characteristic was consistent with the model of a thermal arc discharge, together with a highly collisional cathode sheet.

  19. Theoretical Study of the Vibrational Spectroscopy of the Ethyl Radical

    NASA Astrophysics Data System (ADS)

    Tabor, Daniel P.; Sibert, Edwin. L. Sibert, Iii

    2013-06-01

    The rich spectroscopy of the ethyl radical has attracted the attention of several experimental and theoretical investigations. The purpose of these studies was to elucidate the signatures of hyperconjugation, torsion, inversion, and Fermi coupling in the molecular spectra. Due to the number of degrees of freedom in the system, previous theoretical studies have implemented reduced-dimensional models. Our ultimate goal is a full-dimensional theoretical treatment of the vibrations using both Van Vleck and variational approaches. The methods will be combined with the potential that we have calculated using the CCSD(T) method on the cc-pVTZ basis set. In this talk we will discuss our initial work, which builds up from these reduced-dimensional models. Our calculations use coordinates that exploit the system's G_{12} PI symmetry in a simple fashion. By systematically adding more degrees of freedom to our model, we can determine the effects of specific couplings on the spectroscopy. T. Häber, A. C. Blair, D. J. Nesbitt and M. D. Schuder J. Chem. Phys. {124}, 054316, (2006). G .E. Douberly, unpublished. R. S. Bhatta, A. Gao and D. S. Perry J. Mol. Struct.: THEOCHEM {941}, 22, (2010).

  20. [Study on the treatment turquoise using Raman spectroscopy].

    PubMed

    Chen, Quan-li; Yuan, Xin-qiang; Chen, Jing-zhong; Qi, Li-jian

    2010-07-01

    Due to a variety of the enhancement and treatment turquoises discovered in gem markets, the identification of turquoise is becoming more and more difficult. By using laser Raman spectroscopy analysis, the characteristics of Raman spectra of the pressed and filled turquoises were studied. The results show that laser Raman spectroscopy is an effective technique to identify the enhancement and treatment turquoises and the natural ones, moreover, it's a non-destructive testing method. The Raman spectra of the enhancement and treatment turquoises are resulted mainly from the vibrational mode and frequency of water, hydroxyl units, PO4 tetrahedron and CH2 units. Besides, they have the characteristic Raman spectra peaks at 2,937, 2,883 and 1,451 cm(-1) which are attributed to the stretching vibration and the bending vibration of CH2, respectively. These characteristic Raman vibration bands, it will help to distinguish the natural turquoises and the treatment ones. The study provides a new train of thought on the rapid, accurate, and non-destructive identification of turquoise.