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Sample records for absorption esa band

  1. Atmospheric Solar Heating in Minor Absorption Bands

    NASA Technical Reports Server (NTRS)

    Chou, Ming-Dah

    1998-01-01

    Solar radiation is the primary source of energy driving atmospheric and oceanic circulations. Concerned with the huge computing time required for computing radiative transfer in weather and climate models, solar heating in minor absorption bands has often been neglected. The individual contributions of these minor bands to the atmospheric heating is small, but collectively they are not negligible. The solar heating in minor bands includes the absorption due to water vapor in the photosynthetically active radiation (PAR) spectral region from 14284/cm to 25000/cm, the ozone absorption and Rayleigh scattering in the near infrared, as well as the O2 and CO2 absorption in a number of weak bands. Detailed high spectral- and angular-resolution calculations show that the total effect of these minor absorption is to enhance the atmospheric solar heating by approximately 10%. Depending upon the strength of the absorption and the overlapping among gaseous absorption, different approaches are applied to parameterize these minor absorption. The parameterizations are accurate and require little extra time for computing radiative fluxes. They have been efficiently implemented in the various atmospheric models at NASA/Goddard Space Flight Center, including cloud ensemble, mesoscale, and climate models.

  2. Absorption band Q model for the Earth

    NASA Technical Reports Server (NTRS)

    Anderson, D. L.; Given, J. W.

    1981-01-01

    Attenuation in solids and liquids, as measured by the quality factor Q, is typically frequency dependent. In seismology, however, Q is usually assumed to be independent of frequency. Body wave, surface wave, and normal mode data are used to place constraints on the frequency dependence of Q in the mantle. Specific features of the absorption band model are: low-Q in the seismic band at both the top and the base of the mantle, low-Q for long-period body waves in the outer core, an inner core Q sub s that increases with period, and low Q sub p/Q sub s at short periods in the middle mantle.

  3. Triple-band metamaterial absorption utilizing single rectangular hole

    NASA Astrophysics Data System (ADS)

    Kim, Seung Jik; Yoo, Young Joon; Kim, Young Ju; Lee, YoungPak

    2017-01-01

    In the general metamaterial absorber, the single absorption band is made by the single meta-pattern. Here, we introduce the triple-band metamaterial absorber only utilizing single rectangular hole. We also demonstrate the absorption mechanism of the triple absorption. The first absorption peak was caused by the fundamental magnetic resonance in the metallic part between rectangular holes. The second absorption was generated by induced tornado magnetic field. The process of realizing the second band is also presented. The third absorption was induced by the third-harmonic magnetic resonance in the metallic region between rectangular holes. In addition, the visible-range triple-band absorber was also realized by using similar but smaller single rectangular-hole structure. These results render the simple metamaterials for high frequency in large scale, which can be useful in the fabrication of metamaterials operating in the optical range.

  4. Absorption enhancement of a dual-band metamaterial absorber

    NASA Astrophysics Data System (ADS)

    Zhong, Min; Han, Gui Ming; Liu, Shui Jie; Xu, Bang Li; Wang, Jie; Huang, Hua Qing

    2017-02-01

    In this paper, we propose and fabricate a dual-band metamaterial absorber in 6-24 THz region. Electric field distribution reveal that the first absorption band is obtained from localized surface plasmon (LSP) modes which are excited both on inside and outside edges of each circular-patterned metal-dielectric stack, while the second absorption band is excited by LSP modes on outside edges of each stack. Measured results indicate that the absorption band width can be tuned by increasing the radius of circular-patterned layers or reducing the thickness of dielectric spacing layers. Moreover, the designed dual-band metamaterial absorber is independent on circular-patterned dielectric layer combinations.

  5. Interpretation of absorption bands in airborne hyperspectral radiance data.

    PubMed

    Szekielda, Karl H; Bowles, Jeffrey H; Gillis, David B; Miller, W David

    2009-01-01

    It is demonstrated that hyperspectral imagery can be used, without atmospheric correction, to determine the presence of accessory phytoplankton pigments in coastal waters using derivative techniques. However, care must be taken not to confuse other absorptions for those caused by the presence of pigments. Atmospheric correction, usually the first step to making products from hyperspectral data, may not completely remove Fraunhofer lines and atmospheric absorption bands and these absorptions may interfere with identification of phytoplankton accessory pigments. Furthermore, the ability to resolve absorption bands depends on the spectral resolution of the spectrometer, which for a fixed spectral range also determines the number of observed bands. Based on this information, a study was undertaken to determine under what circumstances a hyperspectral sensor may determine the presence of pigments. As part of the study a hyperspectral imager was used to take high spectral resolution data over two different water masses. In order to avoid the problems associated with atmospheric correction this data was analyzed as radiance data without atmospheric correction. Here, the purpose was to identify spectral regions that might be diagnostic for photosynthetic pigments. Two well proven techniques were used to aid in absorption band recognition, the continuum removal of the spectra and the fourth derivative. The findings in this study suggest that interpretation of absorption bands in remote sensing data, whether atmospherically corrected or not, have to be carefully reviewed when they are interpreted in terms of photosynthetic pigments.

  6. Interpretation of Absorption Bands in Airborne Hyperspectral Radiance Data

    PubMed Central

    Szekielda, Karl H.; Bowles, Jeffrey H.; Gillis, David B.; Miller, W. David

    2009-01-01

    It is demonstrated that hyperspectral imagery can be used, without atmospheric correction, to determine the presence of accessory phytoplankton pigments in coastal waters using derivative techniques. However, care must be taken not to confuse other absorptions for those caused by the presence of pigments. Atmospheric correction, usually the first step to making products from hyperspectral data, may not completely remove Fraunhofer lines and atmospheric absorption bands and these absorptions may interfere with identification of phytoplankton accessory pigments. Furthermore, the ability to resolve absorption bands depends on the spectral resolution of the spectrometer, which for a fixed spectral range also determines the number of observed bands. Based on this information, a study was undertaken to determine under what circumstances a hyperspectral sensor may determine the presence of pigments. As part of the study a hyperspectral imager was used to take high spectral resolution data over two different water masses. In order to avoid the problems associated with atmospheric correction this data was analyzed as radiance data without atmospheric correction. Here, the purpose was to identify spectral regions that might be diagnostic for photosynthetic pigments. Two well proven techniques were used to aid in absorption band recognition, the continuum removal of the spectra and the fourth derivative. The findings in this study suggest that interpretation of absorption bands in remote sensing data, whether atmospherically corrected or not, have to be carefully reviewed when they are interpreted in terms of photosynthetic pigments. PMID:22574053

  7. Increasing efficiency in intermediate band solar cells with overlapping absorptions

    NASA Astrophysics Data System (ADS)

    Krishna, Akshay; Krich, Jacob J.

    2016-07-01

    Intermediate band (IB) materials are promising candidates for realizing high efficiency solar cells. In IB photovoltaics, photons are absorbed in one of three possible electronic transitions—valence to conduction band, valence to intermediate band, or intermediate to conduction band. With fully concentrated sunlight, when the band gaps have been chosen appropriately, the highest efficiency IB solar cells require that these three absorptions be non-overlapping, so absorbed photons of fixed energy contribute to only one transition. The realistic case of overlapping absorptions, where the transitions compete for photons, is generally considered to be a source of loss. We show that overlapping absorptions can in fact lead to significant improvements in IB solar cell efficiencies, especially for IB that are near the middle of the band gap. At low to moderate concentration, the highest efficiency requires overlapping absorptions. We use the detailed-balance method and indicate how much overlap of the absorptions is required to achieve efficiency improvements, comparing with some known cases. These results substantially broaden the set of materials that can be suitable for high-efficiency IB solar cells.

  8. Spectrophotometer spectral bandwidth calibration with absorption bands crystal standard.

    PubMed

    Soares, O D; Costa, J L

    1999-04-01

    A procedure for calibration of a spectral bandwidth standard for high-resolution spectrophotometers is described. Symmetrical absorption bands for a crystal standard are adopted. The method relies on spectral band shape fitting followed by a convolution with the slit function of the spectrophotometer. A reference spectrophotometer is used to calibrate the spectral bandwidth standard. Bandwidth calibration curves for a minimum spectral transmission factor relative to the spectral bandwidth of the reference spectrophotometer are derived for the absorption bands at the wavelength of the band absorption maximum. The family of these calibration curves characterizes the spectral bandwidth standard. We calibrate the spectral bandwidth of a spectrophotometer with respect to the reference spectrophotometer by determining the spectral transmission factor minimum at every calibrated absorption band of the bandwidth standard for the nominal instrument values of the spectral bandwidth. With reference to the standard spectral bandwidth calibration curves, the relation of the spectral bandwidth to the reference spectrophotometer is determined. We determine the discrepancy in the spectrophotometers' spectral bandwidths by averaging the spectral bandwidth discrepancies relative to the standard calibrated values found at the absorption bands considered. A weighted average of the uncertainties is taken.

  9. Photonic band-edge-induced enhancement in absorption and emission

    NASA Astrophysics Data System (ADS)

    Ummer, Karikkuzhi Variyath; Vijaya, Ramarao

    2015-01-01

    An enhancement in photonic band-edge-induced absorption and emission from rhodamine-B dye doped polystyrene pseudo gap photonic crystals is studied. The band-edge-induced enhancement in absorption is achieved by selecting the incident angle of the excitation beam so that the absorption spectrum of the emitter overlaps the photonic band edge. The band-edge-induced enhancement in emission, on the other hand, is possible with and without an enhancement in band-edge-induced absorption, depending on the collection angle of emission. Through a simple set of measurements with suitably chosen angles for excitation and emission, we achieve a maximum enhancement of 70% in emission intensity with band-edge-induced effects over and above the intrinsic emission in the case of self-assembled opals. This is a comprehensive effort to interpret tunable lasing in opals as well as to predict the wavelength of lasing arising as a result of band-edge-induced distributed feedback effects.

  10. Glucose Absorption by the Bacillary Band of Trichuris muris

    PubMed Central

    Hansen, Michael; Nejsum, Peter; Mejer, Helena; Denwood, Matthew; Thamsborg, Stig M.

    2016-01-01

    Background A common characteristic of Trichuris spp. infections in humans and animals is the variable but low efficacy of single-dose benzimidazoles currently used in mass drug administration programmes against human trichuriasis. The bacillary band, a specialised morphological structure of Trichuris spp., as well as the unique partly intracellular habitat of adult Trichuris spp. may affect drug absorption and perhaps contribute to the low drug accumulation in the worm. However, the exact function of the bacillary band is still unknown. Methodology We studied the dependency of adult Trichuris muris on glucose and/or amino acids for survival in vitro and the absorptive function of the bacillary band. The viability of the worms was evaluated using a motility scale from 0 to 3, and the colorimetric assay Alamar Blue was utilised to measure the metabolic activity. The absorptive function of the bacillary band in living worms was explored using a fluorescent glucose analogue (6-NBDG) and confocal microscopy. To study the absorptive function of the bacillary band in relation to 6-NBDG, the oral uptake was minimised or excluded by sealing the oral cavity with glue and agarose. Principal Findings Glucose had a positive effect on both the motility (p < 0.001) and metabolic activity (p < 0.001) of T. muris in vitro, whereas this was not the case for amino acids. The 6-NBDG was observed in the pores of the bacillary band and within the stichocytes of the living worms, independent of oral sealing. Conclusions/Significance Trichuris muris is dependent on glucose for viability in vitro, and the bacillary band has an absorptive function in relation to 6-NBDG, which accumulates within the stichocytes. The absorptive function of the bacillary band calls for an exploration of its possible role in the uptake of anthelmintics, and as a potential anthelmintic target relevant for future drug development. PMID:27588682

  11. Electronic Band Structure and Sub-band-gap Absorption of Nitrogen Hyperdoped Silicon.

    PubMed

    Zhu, Zhen; Shao, Hezhu; Dong, Xiao; Li, Ning; Ning, Bo-Yuan; Ning, Xi-Jing; Zhao, Li; Zhuang, Jun

    2015-05-27

    We investigated the atomic geometry, electronic band structure, and optical absorption of nitrogen hyperdoped silicon based on first-principles calculations. The results show that all the paired nitrogen defects we studied do not introduce intermediate band, while most of single nitrogen defects can introduce intermediate band in the gap. Considering the stability of the single defects and the rapid resolidification following the laser melting process in our sample preparation method, we conclude that the substitutional nitrogen defect, whose fraction was tiny and could be neglected before, should have considerable fraction in the hyperdoped silicon and results in the visible sub-band-gap absorption as observed in the experiment. Furthermore, our calculations show that the substitutional nitrogen defect has good stability, which could be one of the reasons why the sub-band-gap absorptance remains almost unchanged after annealing.

  12. Shape of impurity electronic absorption bands in nematic liquid crystal

    SciTech Connect

    Aver`yanov, E.M.

    1994-11-01

    The impurity-matrix anisotropic static intermolecular interactions, orientation-statistical properties, and electronic structure of uniaxial impurity molecules are shown to have a significant influence on spectral moments of the electronic absorption bands of impurities in the nematic liquid crystal. 14 refs., 3 figs.

  13. Constraints on the absorption band model of Q

    NASA Astrophysics Data System (ADS)

    Lundquist, Gary M.; Cormier, Vernon C.

    1980-10-01

    First order models for the combined depth and frequency dependence of Q are derived and tested using several independent constraints. (1) Using a microphysics approach, the adoption of an absorption band as a first-order model for the frequency dependence of Q is justified, and the expected depth behavior of relaxation times in the earth is derived. The significant new parameter in this model of Q is τ2, the period at the half-amplitude point of the high frequency end of the absorption band. (2) Using observed body-wave spectra, the existence of a frequency dependence in Q is proved, and the average location of that frequency dependence (i.e., τ2) is estimated to be in the range 1 to 2.5 Hz. (3) Under the constraints of Q model ratios, the depth dependence of τ2 is estimated by assuming that a free-oscillation and a body-wave Q model both measure Q from the same absorption band. The resulting τ2 is about 0.04 s in the upper 200 km and then increases exponentially with depth in the mantle to about 1.9 at the core mantle boundary. The Q model ratios are better satisfied if a second absorption band is hypothesized to operate in the depth range of the asthenosphere. In that case, τ2 for the mantle absorption band varies from about 0.09 s in the first 200 km to 4.0 s at 2886 km, and τ2 for the asthenosphere absorption band is about 0.005 s in the depth range 35-220 km. (4) Both classes of Q models are tested in the time domain using synthetic seismograms of Russian and American nuclear explosions. Although trade-offs between source and mantle transfer functions preclude further refinement of the models at this time, a compatibility is demonstrated between the double absorption band model and time domain constraints, including arrival time and pulse shape.

  14. Concerning the Optical Absorption Band of the Hydrated Electron,

    DTIC Science & Technology

    methylene blue ) showed marked nonlinear absorption due to saturation of optical transitions, no such change was observed for hydrated electrons even though the light intensity was varied by > 10 to the 7th power up to 200 photons per hydrated electron per sq cm. Consequently the photoexcited state lifetime is estimated to be than 6 x 10 to the -12th power sec. This finding is discussed briefly in terms of three possible origins for the absorption band, namely that involving excitation to a bound excited state, as a photoionization efficiency profile or as a distribution

  15. INTERACTION OF LASER RADIATION WITH MATTER: Individual induced absorption bands in MgF2

    NASA Astrophysics Data System (ADS)

    Sergeev, A. P.; Sergeev, P. B.

    2008-03-01

    The absorption spectra of MgF2 samples exposed to an electron beam and laser radiation at 248, 308, and 372 nm are investigated. Fourteen individual absorption bands are separated in the spectra. The parameters of the eight spectra of them are obtained for the first time. The separated bands are assigned to the intrinsic defects of the MgF2 crystal.

  16. e-beam irradiation effects on IR absorption bands in single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Ichida, Masao; Nagao, Katsunori; Ikemoto, Yuka; Okazaki, Toshiya; Miyata, Yasumitsu; Kawakami, Akira; Kataura, Hiromichi; Umezu, Ikurou; Ando, Hiroaki

    2017-01-01

    We have measured the absorption and Raman spectral change induced by the irradiation of e-beam. By the irradiation of e-beam on SWNTs thin films, the intensity of defect related Raman band increase, and the peak energy of IR absorption bands shift to the higher energy side. These results indicate that the origin of infrared band is due to the plasmon resonance of finite-length SWNT. We have estimated the effective tube length and defect density from IR absorption peak energy.

  17. Below-band-gap absorption in undoped GaAs at elevated temperatures

    NASA Astrophysics Data System (ADS)

    Wasiak, Michał; Walczak, Jarosław; Motyka, Marcin; Janiak, Filip; Trajnerowicz, Artur; Jasik, Agata

    2017-02-01

    This paper presents results of measurements of optical absorption in undoped epitaxial GaAs for photon energies below the band gap. Absorption spectra were determined from transmission spectra of a thin GaAs layer at several temperatures between 25 °C and 205 °C. We optimized our experiment to investigate the long-wavelength part of the spectrum, where the absorption is relatively low, but significant from the point of view of applications of GaAs in semiconductor lasers. Absorption of 100 cm-1 was observed over 30 nm below the band gap at high temperatures.

  18. Enhancement of broadband optical absorption in photovoltaic devices by band-edge effect of photonic crystals.

    PubMed

    Tanaka, Yoshinori; Kawamoto, Yosuke; Fujita, Masayuki; Noda, Susumu

    2013-08-26

    We numerically investigate broadband optical absorption enhancement in thin, 400-nm thick microcrystalline silicon (µc-Si) photovoltaic devices by photonic crystals (PCs). We realize absorption enhancement by coupling the light from the free space to the large area resonant modes at the photonic band-edge induced by the photonic crystals. We show that multiple photonic band-edge modes can be produced by higher order modes in the vertical direction of the Si photovoltaic layer, which can enhance the absorption on multiple wavelengths. Moreover, we reveal that the photonic superlattice structure can produce more photonic band-edge modes that lead to further optical absorption. The absorption average in wavelengths of 500-1000 nm weighted to the solar spectrum (AM 1.5) increases almost twice: from 33% without photonic crystal to 58% with a 4 × 4 period superlattice photonic crystal; our result outperforms the Lambertian textured structure.

  19. Conformational statistics of molecules with inner rotation and shapes of their electronic absorption bands

    SciTech Connect

    Aver`yanov, E.M.

    1994-10-01

    The effect of conformational statistics of molecules with inner rotation of {pi}-conjugated fragments on the position, intensity, and electronic absorption band shapes is studied in isotropic molecular media. It is shown that the conformational disorder of molecules with one inner rotation degree of freedom exerts an appreciable effect on the shift, inhomogeneous broadening, and asymmetry of the electronic absorption bands. An interpretation of the available experimental data is give. 19 refs., 1 fig.

  20. Ozone absorption cross section measurements in the Wulf bands

    NASA Technical Reports Server (NTRS)

    Anderson, Stuart M.; Hupalo, Peter; Mauersberger, Konrad

    1993-01-01

    A tandem dual-beam spectrometer has been developed to determine ozone absorption cross sections for 13 selected wavelengths between 750 and 975 nm at room temperature. The increasingly pronounced structure in this region may interfere with atmospheric trace gas transitions that are useful for remote sensing and complicate the measurement of aerosols. Ozone concentrations were determined by absorption at the common HeNe laser transition near 632.8 nm using the absolute cross section reported previously. The overall accuracy of these room temperature measurements is generally better than 2 percent. A synoptic near-IR spectrum scaled to these measurements is employed for comparison with results of previous studies.

  1. HAC: Band Gap, Photoluminescence, and Optical/Near-Infrared Absorption

    NASA Technical Reports Server (NTRS)

    Witt, Adolf N.; Ryutov, Dimitri; Furton, Douglas G.

    1996-01-01

    We report results of laboratory measurements which illustrate the wide range of physical properties found among hydrogenated amorphous carbon (HAC) solids. Within this range, HAC can match quantitatively the astronomical phenomena ascribed to carbonaceous coatings on interstellar grains. We find the optical band gap of HAC to be well correlated with other physical properties of HAC of astronomical interest, and conclude that interstellar HAC must be fairly hydrogen-rich with a band gap of E(sub g) is approx. greater than 2.0 eV.

  2. Temperature behavior of optical absorption bands in colored LiF crystals

    NASA Astrophysics Data System (ADS)

    Fastampa, Renato; Missori, Mauro; Braidotti, Maria Chiara; Conti, Claudio; Vincenti, Maria Aurora; Montereali, Rosa Maria

    We measured the optical absorption spectra of thermally treated, gamma irradiated LiF crystals, as a function of temperature in the range 16-300 K. The temperature dependence of intensity, peak position and bandwidth of F and M absorption bands were obtained.

  3. Atmospheric absorption of high frequency noise and application to fractional-octave bands

    NASA Technical Reports Server (NTRS)

    Shields, F. D.; Bass, H. E.

    1977-01-01

    Pure tone sound absorption coefficients were measured at 1/12 octave intervals from 4 to 100 KHz at 5.5K temperature intervals between 255.4 and 310.9 K and at 10 percent relative humidity increments between 0 percent and saturation in a large cylindrical tube (i.d., 25.4 cm; length, 4.8 m). Special solid-dielectric capacitance transducers, one to generate bursts of sound waves and one to terminate the sound path and detect the tone bursts, were constructed to fit inside the tube. The absorption was measured by varying the transmitter receiver separation from 1 to 4 m and observing the decay of multiple reflections or change in amplitude of the first received burst. The resulting absorption was compared with that from a proposed procedure for computing sound absorption in still air. Absorption of bands of noise was numerically computed by using the pure tone results. The results depended on spectrum shape, on filter type, and nonlinearly on propagation distance. For some of the cases considered, comparison with the extrapolation of ARP-866A showed a difference as large as a factor of 2. However, for many cases, the absorption for a finite band was nearly equal to the pure tone absorption at the center frequency of the band. A recommended prediction procedure is described for 1/3 octave band absorption coefficients.

  4. Nonequilibrium Green's function formulation of intersubband absorption for nonparabolic single-band effective mass Hamiltonian

    SciTech Connect

    Kolek, Andrzej

    2015-05-04

    The formulas are derived that enable calculations of intersubband absorption coefficient within nonequilibrium Green's function method applied to a single-band effective-mass Hamiltonian with the energy dependent effective mass. The derivation provides also the formulas for the virtual valence band components of the two-band Green's functions which can be used for more exact estimation of the density of states and electrons and more reliable treatment of electronic transport in unipolar n-type heterostructure semiconductor devices.

  5. Investigation of locally resonant absorption and factors affecting the absorption band of a phononic glass

    NASA Astrophysics Data System (ADS)

    Chen, Meng; Jiang, Heng; Feng, Yafei; Wang, Yuren

    2014-12-01

    We experimentally and theoretically investigated the mechanisms of acoustic absorption in phononic glass to optimize its properties. First, we experimentally studied its locally resonant absorption mechanism. From these results, we attributed its strong sound attenuation to its locally resonant units and its broadband absorption to its networked structure. These experiments also indicated that the porosity and thickness of the phononic glass must be tuned to achieve the best sound absorption at given frequencies. Then, using lumped-mass methods, we studied how the absorption bandgaps of the phononic glass were affected by various factors, including the porosity and the properties of the coating materials. These calculations gave optimal ranges for selecting the porosity, modulus of the coating material, and ratio of the compliant coating to the stiff matrix to achieve absorption bandgaps in the range of 6-30 kHz. This paper provides guidelines for designing phononic glasses with proper structures and component materials to work in specific frequency ranges.

  6. High resolution absorption cross-sections and band oscillator strengths of the Schumann-Runge absorption bands of isotopic oxygen, (O-18)2, at 79 K

    NASA Technical Reports Server (NTRS)

    Yoshino, K.; Freeman, D. E.; Esmond, J. R.; Friedman, R. S.; Parkinson, W. H.

    1988-01-01

    Cross-sections of (O-18)2 at 79 K have been obtained from photoabsorption measurements at various pressures throughout the wavelength region 177.8-197.8 nm with a 6.65 m photoelectric scanning spectrometer equipped with a 2400 lines/mm grating and having an instrumental width (FWHM) of 0.0013 nm. The measured absorption cross-sections of the Schumann-Runge bands (14,0) through (2,0) are, with the exception of the (12,0) band, independent of the instrumental width. The measured cross-sections are presented graphically here and are available at wavenumber intervals of about 0.1/cm as numerical compilations stored on magnetic tape. Band oscillator strengths of those bands have been determined by direct numerical integration of the measured absolute cross-sections and are in excellent agreement with these theoretically calculated values.

  7. Possible spinel absorption bands in S-asteroid visible reflectance spectra

    NASA Technical Reports Server (NTRS)

    Hiroi, T.; Vilas, F.; Sunshine, J. M.

    1994-01-01

    Minor absorption bands in the 0.55 to 0.7 micron wavelength range of reflectance spectra of 10 S asteroids have been found and compared with those of spinel-group minerals using the modified Gaussian model. Most of these S asteroids are consistently shown to have two absorption bands around 0.6 and 0.67 micron. Of the spinel-group minerals examined in this study, the 0.6 and 0.67 micron bands are most consistent with those seen in chromite. Recently, the existence of spinels has also been detected from the absorption-band features around 1 and 2 micron of two S-asteroid reflectance spectra, and chromite has been found in a primitive achondrite as its major phase. These new findings suggest a possible common existence of spinel-group minerals in the solar system.

  8. Hot Bands in Overtone Absorption Transitions: High Temperature Spectra

    DTIC Science & Technology

    1993-03-17

    the overtone transition. ൖ WWIŝST3" 3 24 002 15.NUMBER ,OF ,,A Overtone Spectroscopy, Hot Bands 16. PRKI CODE 17. SECURITY CLASSIFICATION 18...Rev 2-89) aWVPOO AfeD $10 139-18’q wAPI .’ N o, lgi OFFICE OF NAVAL RESEARCH GRANT or CONTRACT N00014-88-K-4130 R&T Code 4131063 Technical Report No...Unannounced fJ Justification ................ Prepared for Publication By ................ Di•.t. ibution I in Availability Codes Avail and /or Dist Special

  9. Varied absorption peaks of dual-band metamaterial absorber analysis by using reflection theory

    NASA Astrophysics Data System (ADS)

    Xiong, Han; Yu, Yan-Tao; Tang, Ming-Chun; Chen, Shi-Yong; Liu, Dan-Ping; Ou, Xiang; Zeng, Hao

    2016-03-01

    Cross-resonator metamaterial absorbers (MMA) have been widely investigated from microwave to optical frequencies. However, only part of the factors influencing the absorption properties were analyzed in previous works at the same time. In order to completely understand how the spacer thickness, dielectric parameter and incidence angle affect the absorption properties of the dual-band MMA, two sets of simulation were performed. It was found that with increasing incident angles, the low-frequency absorption peak showed a blue shift, while the high-frequency absorption peaks showed a red shift. However, with the increase in spacer thickness, both of the absorption peaks showed a red shift. By using the reflection theory expressions, the physical mechanism of the cross-resonator MMA was well explained. This method provides an effective way to analyze multi-band absorber in technology.

  10. Fe-substituted indium thiospinels: New intermediate band semiconductors with better absorption of solar energy

    NASA Astrophysics Data System (ADS)

    Chen, Ping; Chen, Haijie; Qin, Mingsheng; Yang, Chongyin; Zhao, Wei; Liu, Yufeng; Zhang, Wenqing; Huang, Fuqiang

    2013-06-01

    The indium thiospinels In2S3 and MgIn2S4 are promising host for the intermediated band (IB) photovoltaic materials due to their ideal band gap value. Here, the optical properties and electronic structure of Fe-doped In2S3 and MgIn2S4 have been investigated. All the Fe-substituted semiconductors exhibit two additional absorption bands at about 0.7 and 1.25 eV, respectively. The results of first-principles calculations revealed that the Fe substituted at the octahedral In site would introduce a partially filled IB into the band gap. Thanks to the formation of IB, the Fe-substituted semiconductors have the ability to absorb the photons with energies below the band gap. With the wide-spectrum absorption of solar energy, these materials possess potential applications in photovoltaic domain.

  11. The effective air absorption coefficient for predicting reverberation time in full octave bands.

    PubMed

    Wenmaekers, R H C; Hak, C C J M; Hornikx, M C J

    2014-12-01

    A substantial amount of research has been devoted to producing a calculation model for air absorption for pure tones. However, most statistical and geometrical room acoustic prediction models calculate the reverberation time in full octave bands in accordance with ISO 3382-1 (International Organization for Standardization, 2009). So far, the available methods that allow calculation of air absorption in octave bands have not been investigated for room acoustic applications. In this paper, the effect of air absorption on octave band reverberation time calculations is investigated based on calculations. It is found that the approximation method, as described in the standard ANSI S1.26 (American National Standards Institute, 1995), fails to estimate accurate decay curves for full octave bands. In this paper, a method is used to calculate the energy decay curve in rooms based on a summation of pure tones within the band. From this decay curve, which is found to be slightly concave upwards, T20 and T30 can be determined. For different conditions, an effective intensity attenuation coefficient mB ;eff for the full octave bands has been calculated. This mB ;eff can be used for reverberation time calculations, if results are to be compared with T20 or T30 measurements. Also, guidelines are given for the air absorption correction of decay curves, measured in a scale model.

  12. Measurement of the depolarization ratio of Rayleigh scattering at absorption bands

    NASA Astrophysics Data System (ADS)

    Anglister, J.; Steinberg, I. Z.

    1981-01-01

    Measurements of the depolarization ratio ρv of light scattered by the pigments lycopene and β-carotene at the red part of their absorption bands yielded values which are very close to the theoretical value 1/3 of a fully anisotropic molecular polarizability, i.e., that due to an electric dipole moment. Measurements of ρv at the blue edge of the visible absorption band of pinacyanol chloride yielded a value of 0.75 at 472.2 nm, which is the maximum value that a depolarization ratio can assume, and is attained if the average molecular polarizability is zero. This is possible only if the diagonalized polarizability tensor has at least one negative element to counterbalance the positive ones. A negative refractive index at the blue edge of the absorption band is thus experimentally demonstrated.

  13. AKARI observations of ice absorption bands towards edge-on YSOs

    NASA Astrophysics Data System (ADS)

    Aikawa, Y.; Kamuro, D.; Sakon, I.; Itoh, Y.; Noble, J. A.; Pontoppidan, K. M., Fraser, H. J.; Terada, H.; Tamura, M.; Kandori, R.; Kawamura, A.; Ueno, M.

    2011-05-01

    Circumstellar disks and envelopes of low-mass YSOs contain significant amounts of ice. Such icy material will evolve to volatile components of planetary systems, such as comets in our solar system. In order to investigate the composition and evolution of circumstellar ice around low-mass YSOs, we have observed ice absorption bands towards eight YSOs ranging from class 0 to class II, among which seven are associated with edge-on disks. Slit-less spectroscopic observations are performed using the grism mode of Infrared Camera (IRC) on board AKARI, which enables us to obtain full NIR spectra from 2.5 μm to 5 μm, including the CO_2 band and the blue wing of the H_2O band, which are not accessible from the ground. We developed procedures to reduce the spectra of targets with nebulosity. The spectra are fitted with polynomial baselines to derive the absorption spectra. Then we fit the molecular absorption bands with the laboratory spectra from the database, considering the instrumental line profile and the spectral resolution of the dispersion element. Towards the Class 0-I sources, absorption bands of H_2O, CO_2, CO and XCN (OCN^-) are clearly detected. Weak features of 13CO_2, HDO, the C-H band, and gaseous CO are detected as well. OCS ice absorption is tentatively detected towards IRC-L1041-2. The detected features would mostly originate in the cold envelope, while CO gas and OCN^- could originate in the region close to the protostar. Towards class II stars, H_2O ice band is detected. We also detected H_2O ice, CO_2 ice and tentative CO gas features of the foreground component of class II stars.

  14. Full band structure calculation of two-photon indirect absorption in bulk silicon

    SciTech Connect

    Cheng, J. L.; Rioux, J.; Sipe, J. E.

    2011-03-28

    Degenerate two-photon indirect absorption in silicon is an important limiting effect on the use of silicon structures for all-optical information processing at telecommunication wavelengths. We perform a full band structure calculation to investigate two-photon indirect absorption in bulk silicon, using a pseudopotential description of the energy bands and an adiabatic bond charge model to describe phonon dispersion and polarization. Our results agree well with some recent experimental results. The transverse acoustic/optical phonon-assisted processes dominate.

  15. Parallel LC circuit model for multi-band absorption and preliminary design of radiative cooling.

    PubMed

    Feng, Rui; Qiu, Jun; Liu, Linhua; Ding, Weiqiang; Chen, Lixue

    2014-12-15

    We perform a comprehensive analysis of multi-band absorption by exciting magnetic polaritons in the infrared region. According to the independent properties of the magnetic polaritons, we propose a parallel inductance and capacitance(PLC) circuit model to explain and predict the multi-band resonant absorption peaks, which is fully validated by using the multi-sized structure with identical dielectric spacing layer and the multilayer structure with the same strip width. More importantly, we present the application of the PLC circuit model to preliminarily design a radiative cooling structure realized by merging several close peaks together. This omnidirectional and polarization insensitive structure is a good candidate for radiative cooling application.

  16. Emergence of Very Broad Infrared Absorption Band By Hyperdoping of Silicon with Chalcogens

    DTIC Science & Technology

    2013-06-03

    measured by Hall effect in Ref. 9 (crosses) as functions of implanted sulfur dose. (c) Calculated reflectivity by Kramers- Kronig transformation of the...MIR band is small enough, this assumption is reasonable according to the Kramers- Kronig relationship between optical absorption and reflectivity...calculated by a Kramers- Kronig transformation of the absorption spectrum shown in Fig. 1(a) and the results are shown in Fig. 1(c). However, the a value

  17. A band model for melanin deducted from optical absorption and photoconductivity experiments.

    PubMed

    Crippa, P R; Cristofoletti, V; Romeo, N

    1978-01-03

    Natural and synthetic melanins have been studied by optical absorption and photoconductivity measurements in the range 200--700 nm. Both optical absorption and photoconductivity increase in the ultraviolet region, and a negative photoconductivity was observed with a maximum near 500 nm. This behaviour has been interpreted by the band model of amorphous materials and an "optical gap" of 3.4 eV has been determined.

  18. High sensitivity ultra-broad-band absorption spectroscopy of inductively coupled chlorine plasma

    NASA Astrophysics Data System (ADS)

    Marinov, Daniil; Foucher, Mickaël; Campbell, Ewen; Brouard, Mark; Chabert, Pascal; Booth, Jean-Paul

    2016-06-01

    We propose a method to measure the densities of vibrationally excited Cl2(v) molecules in levels up to v  =  3 in pure chlorine inductively coupled plasmas (ICPs). The absorption continuum of Cl2 in the 250-450 nm spectral range is deconvoluted into the individual components originating from the different vibrational levels of the ground state, using a set of ab initio absorption cross sections. It is shown that gas heating at constant pressure is the major depletion mechanism of the Cl2 feedstock in the plasma. In these line-integrated absorption measurements, the absorption by the hot (and therefore rarefied) Cl2 gas in the reactor centre is masked by the cooler (and therefore denser) Cl2 near the walls. These radial gradients in temperature and density make it difficult to assess the degree of vibrational excitation in the centre of the reactor. The observed line-averaged vibrational distributions, when analyzed taking into account the radial temperature gradient, suggest that vibrational and translational degrees of freedom in the plasma are close to local equilibrium. This can be explained by efficient vibrational-translational (VT) relaxation between Cl2 and Cl atoms. Besides the Cl2(v) absorption band, a weak continuum absorption is observed at shorter wavelengths, and is attributed to photodetachment of Cl- negative ions. Thus, line-integrated densities of negative ions in chlorine plasmas can be directly measured using broad-band absorption spectroscopy.

  19. Diversity in the Visible-NIR Absorption Band Characteristics of Lunar and Asteroidal Plagioclase

    NASA Technical Reports Server (NTRS)

    Hiroi, T.; Kaiden, H.; Misawa, K.; Kojima, H.; Uemoto, K.; Ohtake, M.; Arai, T.; Sasaki, S.; Takeda, H.; Nyquist, L. E.; Shih, C.-Y.

    2012-01-01

    Studying the visible and near-infrared (VNIR) spectral properties of plagioclase has been challenging because of the difficulty in obtaining good plagioclase separates from pristine planetary materials such as meteorites and returned lunar samples. After an early study indicated that the 1.25 m band position of plagioclase spectrum might be correlated with the molar percentage of anorthite (An#) [1], there have been few studies which dealt with the band center behavior. In this study, the VNIR absorption band parameters of plagioclase samples have been derived using the modified Gaussian model (MGM) [2] following a pioneering study by [3].

  20. Infrared band absorptance correlations and applications to nongray radiation. [mathematical models of absorption spectra for nongray atmospheres in order to study air pollution

    NASA Technical Reports Server (NTRS)

    Tiwari, S. N.; Manian, S. V. S.

    1976-01-01

    Various mathematical models for infrared radiation absorption spectra for atmospheric gases are reviewed, and continuous correlations for the total absorptance of a wide band are presented. Different band absorptance correlations were employed in two physically realistic problems (radiative transfer in gases with internal heat source, and heat transfer in laminar flow of absorbing-emitting gases between parallel plates) to study their influence on final radiative transfer results. This information will be applied to the study of atmospheric pollutants by infrared radiation measurement.

  1. Laboratory Measurements of the 940, 1130, and 1370 nm Water Vapor Absorption Band Profiles

    NASA Technical Reports Server (NTRS)

    Giver, Lawrence P.; Gore, Warren J.; Pilewskie, P.; Freedman, R. S.; Chackerian, C., Jr.; Varanasi, P.

    2001-01-01

    We have used the solar spectral flux radiometer (SSFR) flight instrument with the Ames 25 meter base-path White cell to obtain about 20 moderate resolution (8 nm) pure water vapor spectra from 650 to 1650 nm, with absorbing paths from 806 to 1506 meters and pressures up to 14 torr. We also obtained a set at 806 meters with several different air-broadening pressures. Model simulations were made for the 940, 1130, and 1370 nm absorption bands for some of these laboratory conditions using the Rothman, et al HITRAN-2000 linelist. This new compilation of HITRAN includes new intensity measurements for the 940 nm region. We compared simulations for our spectra of this band using HITRAN-2000 with simulations using the prior HITRAN-1996. The simulations of the 1130 nm band show about 10% less absorption than we measured. There is some evidence that the total intensity of this band is about 38% stronger than the sum of the HITRAN line intensities in this region. In our laboratory conditions the absorption depends approximately on the square root of the intensity. Thus, our measurements agree that the band is stronger than tabulated in HITRAN, but by about 20%, substantially less than the published value. Significant differences have been shown between Doppler-limited resolution spectra of the 1370 nm band obtained at the Pacific Northwest National Laboratory and HITRAN simulations. Additional new intensity measurements in this region are continuing to be made. We expect the simulations of our SSFR lab data of this band will show the relative importance of improving the HITRAN line intensities of this band for atmospheric measurements.

  2. Isothermal annealing of a 620 nm optical absorption band in Brazilian topaz crystals

    NASA Astrophysics Data System (ADS)

    Isotani, Sadao; Matsuoka, Masao; Albuquerque, Antonio Roberto Pereira Leite

    2013-04-01

    Isothermal decay behaviors, observed at 515, 523, 562, and 693 K, for an optical absorption band at 620 nm in gamma-irradiated Brazilian blue topaz were analyzed using a kinetic model consisting of O- bound small polarons adjacent to recombination centers (electron traps). The kinetic equations obtained on the basis of this model were solved using the method of Runge-Kutta and the fit parameters describing these defects were determined with a grid optimization method. Two activation energies of 0.52±0.08 and 0.88±0.13 eV, corresponding to two different structural configurations of the O- polarons, explained well the isothermal decay curves using first-order kinetics expected from the kinetic model. On the other hand, thermoluminescence (TL) emission spectra measured at various temperatures showed a single band at 400 nm in the temperature range of 373-553 K in which the 620 nm optical absorption band decreased in intensity. Monochromatic TL glow curve data at 400 nm extracted from the TL emission spectra observed were found to be explained reasonably by using the knowledge obtained from the isothermal decay analysis. This suggests that two different structural configurations of O- polarons are responsible for the 620 nm optical absorption band and that the thermal annealing of the polarons causes the 400 nm TL emission band.

  3. High resolution absorption cross-sections and band oscillator strengths of the Schumann-Runge absorption bands of isotopic oxygen, (0-16)(0-18), at 79 K

    NASA Technical Reports Server (NTRS)

    Yoshino, K.; Freeman, D. E.; Esmond, J. R.; Friedman, R. S.; Parkinson, W. H.

    1989-01-01

    Cross-sections of (0-16)(0-18) at 79 K have been obtained from photoabsorption measurements on mixtures of (0-16)2, (0-18)2, and (0-16)(0-18) at various pressures throughout the wavelength region 180.5-195.3 nm with a 6.65 m photoelectric scanning spectrometer equipped with a 2400 lines/mm grating and having an instrumental width (FWHM) of 0.0013 nm. The measured absorption cross-sections of the (0-16)(0-18) Schumann-Runge bands (11.0)-(3.0) are independent of the instrumental width. The measured cross-sections are presented graphically.

  4. Effect of Sn on the optical band gap determined using absorption spectrum fitting method

    SciTech Connect

    Heera, Pawan; Kumar, Anup; Sharma, Raman

    2015-05-15

    We report the preparation and the optical studies on tellurium rich glasses thin films. The thin films of Se{sub 30}Te{sub 70-x} Sn{sub x} system for x= 0, 1.5, 2.5 and 4.5 glassy alloys prepared by melt quenching technique are deposited on the glass substrate using vacuum thermal evaporation technique. The analysis of absorption spectra in the spectral range 400nm–4000 nm at room temperature obtained from UV-VIS-NIR spectrophotometer [Perkin Elmer Lamda-750] helps us in the optical characterization of the thin films under study. The absorption spectrum fitting method is applied by using the Tauc’s model for estimating the optical band gap and the width of the band tail of the thin films. The optical band gap is calculated and is found to decrease with the Sn content.

  5. Dual-Band Perfect Absorption by Breaking the Symmetry of Metamaterial Structure

    NASA Astrophysics Data System (ADS)

    Hai, Le Dinh; Qui, Vu Dinh; Dinh, Tiep Hong; Hai, Pham; Giang, Trinh Thị; Cuong, Tran Manh; Tung, Bui Son; Lam, Vu Dinh

    2017-02-01

    Since the first proposal of Landy et al. (Phys Rev Lett 100:207402, 2008), the metamaterial perfect absorber (MPA) has rapidly become one of the most crucial research trends. Recently, dual-band, multi-band and broadband MPA have been highly desirable in electronic applications. In this paper, we demonstrate and evaluate a MPA structure which can generate dual-band absorption operating at the microwave frequency by breaking the symmetry of structure. There is an agreement between simulation and experimental results. The results can be explained by using the equivalent LC circuit and the electric field distribution of this structure. In addition, various structures with different symmetry configurations were studied to gain greater insight into the absorption.

  6. Jet-cooled infrared absorption spectrum of the v4 fundamental band of HCOOH and HCOOD

    NASA Astrophysics Data System (ADS)

    Luo, Wei; Zhang, Yulan; Li, Wenguang; Duan, Chuanxi

    2017-04-01

    The jet-cooled absorption spectrum of the v4 fundamental band of normal formic acid (HCOOH) and deuterated formic acid (HCOOD) was recorded in the frequency range of 1370-1392 cm-1 with distributed-feedback quantum cascade lasers (DFB-QCLs) as the tunable infrared radiations. A segmented rapid-scan data acquisition scheme was developed for pulsed supersonic jet infrared laser absorption spectroscopy based on DFB-QCLs with a moderate vacuum pumping capacity. The unperturbed band-origin and rotational constants in the excited vibrational state were determined for both HCOOH and HCOOD. The unperturbed band-origin locates at 1379.05447(11) cm-1 for HCOOH, and 1366.48430(39) cm-1 for HCOOD, respectively.

  7. Understanding of sub-band gap absorption of femtosecond-laser sulfur hyperdoped silicon using synchrotron-based techniques

    NASA Astrophysics Data System (ADS)

    Limaye, Mukta V.; Chen, S. C.; Lee, C. Y.; Chen, L. Y.; Singh, Shashi B.; Shao, Y. C.; Wang, Y. F.; Hsieh, S. H.; Hsueh, H. C.; Chiou, J. W.; Chen, C. H.; Jang, L. Y.; Cheng, C. L.; Pong, W. F.; Hu, Y. F.

    2015-06-01

    The correlation between sub-band gap absorption and the chemical states and electronic and atomic structures of S-hyperdoped Si have been extensively studied, using synchrotron-based x-ray photoelectron spectroscopy (XPS), x-ray absorption near-edge spectroscopy (XANES), extended x-ray absorption fine structure (EXAFS), valence-band photoemission spectroscopy (VB-PES) and first-principles calculation. S 2p XPS spectra reveal that the S-hyperdoped Si with the greatest (~87%) sub-band gap absorption contains the highest concentration of S2- (monosulfide) species. Annealing S-hyperdoped Si reduces the sub-band gap absorptance and the concentration of S2- species, but significantly increases the concentration of larger S clusters [polysulfides (Sn2-, n > 2)]. The Si K-edge XANES spectra show that S hyperdoping in Si increases (decreased) the occupied (unoccupied) electronic density of states at/above the conduction-band-minimum. VB-PES spectra evidently reveal that the S-dopants not only form an impurity band deep within the band gap, giving rise to the sub-band gap absorption, but also cause the insulator-to-metal transition in S-hyperdoped Si samples. Based on the experimental results and the calculations by density functional theory, the chemical state of the S species and the formation of the S-dopant states in the band gap of Si are critical in determining the sub-band gap absorptance of hyperdoped Si samples.

  8. AKARI observations of ice absorption bands towards edge-on young stellar objects

    NASA Astrophysics Data System (ADS)

    Aikawa, Y.; Kamuro, D.; Sakon, I.; Itoh, Y.; Terada, H.; Noble, J. A.; Pontoppidan, K. M.; Fraser, H. J.; Tamura, M.; Kandori, R.; Kawamura, A.; Ueno, M.

    2012-02-01

    Context. Circumstellar disks and envelopes of low-mass young stellar objects (YSOs) contain significant amounts of ice. Such icy material will evolve to become volatile components of planetary systems, such as comets in our solar system. Aims: To investigate the composition and evolution of circumstellar ice around low-mass young stellar objects (YSOs), we observed ice absorption bands in the near infrared (NIR) towards eight YSOs ranging from class 0 to class II, among which seven are associated with edge-on disks. Methods: We performed slit-less spectroscopic observations using the grism mode of the InfraRed Camera (IRC) on board AKARI, which enables us to obtain full NIR spectra from 2.5 μm to 5 μm, including the CO2 band and the blue wing of the H2O band, which are inaccessible from the ground. We developed procedures to carefully process the spectra of targets with nebulosity. The spectra were fitted with polynomial baselines to derive the absorption spectra. The molecular absorption bands were then fitted with the laboratory database of ice absorption bands, considering the instrumental line profile and the spectral resolution of the grism dispersion element. Results: Towards the class 0-I sources (L1527, IRC-L1041-2, and IRAS 04302), absorption bands of H2O, CO2, CO, and XCN are clearly detected. Column density ratios of CO2 ice and CO ice relative to H2O ice are 21-28% and 13-46%, respectively. If XCN is OCN-, its column density is as high as 2-6% relative to H2O ice. The HDO ice feature at 4.1 μm is tentatively detected towards the class 0-I sources and HV Tau. Non-detections of the CH-stretching mode features around 3.5 μm provide upper limits to the CH3OH abundance of 26% (L1527) and 42% (IRAS 04302) relative to H2O. We tentatively detect OCS ice absorption towards IRC-L1041-2. Towards class 0-I sources, the detected features should mostly originate in the cold envelope, while CO gas and OCN- could originate in the region close to the protostar

  9. Analysis of wavelength-dependent photoisomerization quantum yields in bilirubins by fitting two exciton absorption bands

    NASA Astrophysics Data System (ADS)

    Mazzoni, M.; Agati, G.; Troup, G. J.; Pratesi, R.

    2003-09-01

    The absorption spectra of bilirubins were deconvoluted by two Gaussian curves of equal width representing the exciton bands of the non-degenerate molecular system. The two bands were used to study the wavelength dependence of the (4Z, 15Z) rightarrow (4Z, 15E) configurational photoisomerization quantum yield of the bichromophoric bilirubin-IXalpha (BR-IX), the intrinsically asymmetric bile pigment associated with jaundice and the symmetrically substituted bilirubins (bilirubin-IIIalpha and mesobilirubin-XIIIalpha), when they are irradiated in aqueous solution bound to human serum albumin (HSA). The same study was performed for BR-IX in ammoniacal methanol solution (NH4OH/MeOH). The quantum yields of the configurational photoprocesses were fitted with a combination function of the two Gaussian bands normalized to the total absorption, using the proportionality coefficients and a scaling factor as parameters. The decrease of the (4Z, 15Z) rightarrow (4Z, 15E) quantum yield with increasing wavelength, which occurs for wavelengths longer than the most probable Franck-Condon transition of the molecule, did not result in a unique function of the exciton absorptions. In particular we found two ranges corresponding to different exciton interactions with different proportionality coefficients and scaling factors. The wavelength-dependent photoisomerization of bilirubins was described as an abrupt change in quantum yield as soon as the resulting excitation was strongly localized in each chromophore. The change was correlated to a variation of the interaction between the two chromophores when the short-wavelength exciton absorption became vanishingly small. With the help of the circular dichroism (CD) spectrum of BR-IX in HSA, a small band was resolved in the bilirubin absorption spectrum, delivering part of the energy required for the (4Z, 15Z) rightarrow (4Z, 15E) photoisomerization of the molecule.

  10. Assignment and rotational analysis of new absorption bands of carbon dioxide isotopologues in Venus spectra

    NASA Astrophysics Data System (ADS)

    Robert, S.; Borkov, Yu. G.; Vander Auwera, J.; Drummond, R.; Mahieux, A.; Wilquet, V.; Vandaele, A. C.; Perevalov, V. I.; Tashkun, S. A.; Bertaux, J. L.

    2013-01-01

    We present absorption bands of carbon dioxide isotopologues, detected by the Solar Occultation for the Infrared Range (SOIR) instrument on board the Venus Express Satellite. The SOIR instrument combines an echelle spectrometer and an Acousto-Optical Tunable Filter (AOTF) for order selection. It performs solar occultation measurements in the Venus atmosphere in the IR region (2.2-4.3 μm), at a resolution of 0.12-0.18 cm-1. The wavelength range probed by SOIR allows a detailed chemical inventory of the Venus atmosphere above the cloud layer (65-150 km) to be made with emphasis on the vertical distributions of gases. Thanks to the SOIR spectral resolution, a new CO2 absorption band was identified: the 21101-01101 band of 16O12C18O with R branch up to J=31. Two other previously reported bands were observed dispelling any doubts about their identifications: the 20001-00001 band of 16O13C18O [Villanueva G, et al. J Quant Spectrosc Radiat Transfer 2008;109:883-894] and the 01111-00001 band of 16O12C18O [Villanueva G, et al. J Quant Spectrosc Radiat Transfer 2008;109:883-894 and Wilquet V, et al. J Quant Spectrosc Radiat Transfer 2008;109:895-905]. These bands were analyzed, and spectroscopic constants characterizing them were obtained. The rotational assignment of the 20001-00001 band was corrected. The present measurements are compared with data available in the HITRAN database.

  11. The Soret absorption band of isolated chlorophyll a and b tagged with quaternary ammonium ions.

    PubMed

    Stockett, Mark H; Musbat, Lihi; Kjær, Christina; Houmøller, Jørgen; Toker, Yoni; Rubio, Angel; Milne, Bruce F; Brøndsted Nielsen, Steen

    2015-10-21

    We have performed gas-phase absorption spectroscopy in the Soret-band region of chlorophyll (Chl) a and b tagged by quaternary ammonium ions together with time-dependent density functional theory (TD-DFT) calculations. This band is the strongest in the visible region of metalloporphyrins and an important reporter on the microenvironment. The cationic charge tags were tetramethylammonium, tetrabutylammonium, and acetylcholine, and the dominant dissociation channel in all cases was breakage of the complex to give neutral Chl and the charge tag as determined by photoinduced dissociation mass spectroscopy. Two photons were required to induce fragmentation on the time scale of the experiment (microseconds). Action spectra were recorded where the yield of the tag as a function of excitation wavelength was sampled. These spectra are taken to represent the corresponding absorption spectra. In the case of Chl a we find that the tag hardly influences the band maximum which for all three tags is at 403 ± 5 nm. A smaller band with maximum at 365 ± 10 nm was also measured for all three complexes. The spectral quality is worse in the case of Chl b due to lower ion beam currents; however, there is clear evidence for the absorption being to the red of that of Chl a (most intense peak at 409 ± 5 nm) and also a more split band. Our results demonstrate that the change in the Soret-band spectrum when one peripheral substituent (CH3) is replaced by another (CHO) is an intrinsic effect. First principles TD-DFT calculations agree with our experiments, supporting the intrinsic nature of the difference between Chl a and b and also displaying minimal spectral changes when different charge tags are employed. The deviations between theory and experiment have allowed us to estimate that the Soret-band absorption maxima in vacuo for the neutral Chl a and Chl b should occur at 405 nm and 413 nm, respectively. Importantly, the Soret bands of the isolated species are significantly blueshifted

  12. PRINCIPAL INFRARED ABSORPTION BANDS OF SOME DERIVATIVES OF 1,3-DINITROBENZENE AND 1,3,5TRINITROBENZENE,

    DTIC Science & Technology

    The frequencies of the strong infrared absorption bands of 46 derivatives of di- and tri-nitrobenzene were measured and tabulated. The vibrational ... modes producing these absorptions were assigned in most cases. The effect of structure on the frequency of the absorption due to each of the modes is discussed, with emphasis on identifying unknowns. (Author)

  13. Solvatochromic Shifts on Absorption and Fluorescence Bands of N,N-Dimethylaniline.

    PubMed

    Fdez Galván, Ignacio; Elena Martín, M; Muñoz-Losa, Aurora; Aguilar, Manuel A

    2009-02-10

    A theoretical study of the absorption and fluorescence UV/vis spectra of N,N-dimethylaniline in different solvents has been performed, using a method combining quantum mechanics, molecular mechanics, and the mean field approximation. The transitions between the three lowest-lying states have been calculated in vacuum as well as in cyclohexane, tetrahydrofuran, and water. The apparent anomalies experimentally found in water (a blue shift in the absorption bands with respect to the trend in other solvents, and an abnormally high red shift for the fluorescence band) are well reproduced and explained in view of the electronic structure of the solute and the solvent distribution around it. Additional calculations were done with a mixture of cyclohexane and tetrahydrofuran as solvent, which displays a nonlinear solvatochromic shift. Results, although not conclusive, are consistent with experiment and provide a possible explanation for the nonlinear behavior in the solvent mixture.

  14. An alternative model for photodynamic therapy of cancers: Hot-band absorption

    NASA Astrophysics Data System (ADS)

    Wang, Jing; Chen, Jiyao

    2013-12-01

    The sulfonated aluminum phthalocyanine (AlPcS), a photosensitizer for photodynamic cancer therapy (PDT), has an absorption tail in the near-infrared region (700-900 nm) which is so-called hot band absorption (HBA). With the HBA of 800 nm, the up-conversion excitation of AlPcS was achieved followed by the anti-Stocks emission (688 nm band) and singlet oxygen production. The HBA PDT of AlPcS seriously damaged the KB and HeLa cancer cells, with a typical light dose dependent mode. Particularly, the in vitro experiments with the AlPcS shielding solutions further showed that the HBA PDT can overcome a self-shielding effect benefiting the PDT applications.

  15. PHASE ANGLE EFFECTS ON 3 μm ABSORPTION BAND ON CERES: IMPLICATIONS FOR DAWN MISSION

    SciTech Connect

    Takir, D.; Reddy, V.; Sanchez, J. A.; Corre, L. Le; Hardersen, P. S.; Nathues, A.

    2015-05-01

    Phase angle-induced spectral effects are important to characterize since they affect spectral band parameters such as band depth and band center, and therefore skew mineralogical interpretations of planetary bodies via reflectance spectroscopy. Dwarf planet (1) Ceres is the next target of NASA’s Dawn mission, which is expected to arrive in 2015 March. The visible and near-infrared mapping spectrometer (VIR) on board Dawn has the spatial and spectral range to characterize the surface between 0.25–5.0 μm. Ceres has an absorption feature at 3.0 μm due to hydroxyl- and/or water-bearing minerals. We analyzed phase angle-induced spectral effects on the 3 μm absorption band on Ceres using spectra measured with the long-wavelength cross-dispersed (LXD: 1.9–4.2 μm) mode of the SpeX spectrograph/imager at the NASA Infrared Telescope Facility. Ceres LXD spectra were measured at different phase angles ranging from 0.°7 to 22°. We found that the band center slightly increases from 3.06 μm at lower phase angles (0.°7 and 6°) to 3.07 μm at higher phase angles (11° and 22°), the band depth decreases by ∼20% from lower phase angles to higher phase angles, and the band area decreases by ∼25% from lower phase angles to higher phase angles. Our results will have implications for constraining the abundance of OH on the surface of Ceres from VIR spectral data, which will be acquired by Dawn starting spring 2015.

  16. Collisional Induced Absorption (CIA) bands measured in the IR spectral range .

    NASA Astrophysics Data System (ADS)

    Stefani, S.; Piccioni, G.; Snels, M.; Adriani, A.; Grassi, D.

    In this work we present two experimental setup able to characterize the optical properties of gases, in particular CO_2 and H_2, at typically planetary conditions. The apparatus consists of a Fourier Transform InfraRed (FT-IT) interferometer able to work in a wide spectral range, from 350 to 25000 cm-1 (0.4 to 29 mu m ) with a relatively high spectral resolution, from 10 to 0.07 cm-1. Two dedicated gas cells have been integrated with the FT-IR. The first, called High Pressure High Temperature (HP-HT), can support pressures up to 300 bar, temperatures up to 300oC and is characterized by an optical path of 2 cm. The second one, a Multi Pass (MP) absorption gas cell, is designed to have a variable optical path, from 2.5 to 30 m, can be heated up to 200o and operate at pressures up to 10 bar. In this paper, measurements of Collision-Induced Absorption (CIA) bands in carbon dioxide and hydrogen recorded in the InfraRed spectral range will be presented. In principle, linear symmetric molecules such as CO_2 and H_2 possess no dipole moment, but, even when the pressure is only a few bar, we have observed the Collisional Induced Absorption (CIA) bands. This absorption results from a short-time collisional interaction between molecules. The band integrated intensity shows a quadratic dependence versus density opposed to the absorption by isolated molecules, which follows Beer's law \\citep{Beer's}. This behaviour suggests an absorption by pairs rather than by individual molecules. The bands integrated intensities show a linear dependence vs square density according to \\citep {CIA Shape} and \\citep{CIA posi}. For what concerns the H_2 CIA bands, a preliminary comparison between simulated data obtained with the model described in \\citep{CIA H2}and measured, shows a good agreement. These processes are very relevant in the dense atmospheres of planets, such as those of Venus and Jupiter and also in extrasolar planets. A detailed knowledge of these contributions is very

  17. Decomposing the First Absorption Band of OCS Using Photofragment Excitation Spectroscopy.

    PubMed

    Toulson, Benjamin W; Murray, Craig

    2016-09-01

    Photofragment excitation spectra of carbonyl sulfide (OCS) have been recorded from 212-260 nm by state-selectively probing either electronically excited S((1)D) or ground state S((3)P) photolysis products via 2 + 1 resonance-enhanced multiphoton ionization. Probing the major S((1)D) product results in a broad, unstructured action spectrum that reproduces the overall shape of the first absorption band. In contrast, spectra obtained probing S((3)P) products display prominent resonances superimposed on a broad continuum; the resonances correspond to the diffuse vibrational structure observed in the conventional absorption spectrum. The vibrational structure is assigned to four progressions, each dominated by the C-S stretch, ν1, following direct excitation to quasi-bound singlet and triplet states. The S((3)PJ) products are formed with a near-statistical population distribution over the J = 2, 1, and 0 spin-orbit levels across the wavelength range investigated. Although a minor contributor to the S atom yield near the peak of the absorption cross section, the relative yield of S((3)P) increases significantly at longer wavelengths. The experimental measurements validate recent theoretical work characterizing the electronic states responsible for the first absorption band by Schmidt and co-workers.

  18. Search for CO absorption bands in IUE far-ultraviolet spectra of cool stars

    NASA Technical Reports Server (NTRS)

    Gessner, Susan E.; Carpenter, Kenneth G.; Robinson, Richard D.

    1994-01-01

    Observations of the red supergiant (M2 Iab) alpha Ori with the Goddard High Resolution Spectrograph (GHRS) on board the Hubble Space Telescope (HST) have provided an unambiguous detection of a far-ultraviolet (far-UV) chromospheric continuum on which are superposed strong molecular absorption bands. The absorption bands have been identified by Carpenter et al. (1994) with the fourth-positive A-X system of CO and are likely formed in the circumstellar shell. Comparison of these GHRS data with archival International Ultraviolet Explorer (IUE) spectra of alpha Ori indicates that both the continuum and the CO absorption features can be seen with IUE, especially if multiple IUE spectra, reduced with the post-1981 IUESIPS extraction procedure (i.e., with an oversampling slit), are carefully coadded to increase the signal to noise over that obtainable with a single spectrum. We therefore initiated a program, utilizing both new and archival IUE Short Wavelength Prime (SWP) spectra, to survey 15 cool, low-gravity stars, including alpha Ori, for the presence of these two new chromospheric and circumstellar shell diagnostics. We establish positive detections of far-UV stellar continua, well above estimated IUE in-order scattered light levels, in spectra of all of the program stars. However, well-defined CO absorption features are seen only in the alpha Ori spectra, even though spectra of most of the program stars have sufficient signal to noise to allow the dectection of features of comparable magnitude to the absorptions seen in alpha Ori. Clearly if CO is present in the circumstellar environments of any of these stars, it is at much lower column densities.

  19. Understanding of sub-band gap absorption of femtosecond-laser sulfur hyperdoped silicon using synchrotron-based techniques

    PubMed Central

    Limaye, Mukta V.; Chen, S. C.; Lee, C. Y.; Chen, L. Y.; Singh, Shashi B.; Shao, Y. C.; Wang, Y. F.; Hsieh, S. H.; Hsueh, H. C.; Chiou, J. W.; Chen, C. H.; Jang, L. Y.; Cheng, C. L.; Pong, W. F.; Hu, Y. F.

    2015-01-01

    The correlation between sub-band gap absorption and the chemical states and electronic and atomic structures of S-hyperdoped Si have been extensively studied, using synchrotron-based x-ray photoelectron spectroscopy (XPS), x-ray absorption near-edge spectroscopy (XANES), extended x-ray absorption fine structure (EXAFS), valence-band photoemission spectroscopy (VB-PES) and first-principles calculation. S 2p XPS spectra reveal that the S-hyperdoped Si with the greatest (~87%) sub-band gap absorption contains the highest concentration of S2− (monosulfide) species. Annealing S-hyperdoped Si reduces the sub-band gap absorptance and the concentration of S2− species, but significantly increases the concentration of larger S clusters [polysulfides (Sn2−, n > 2)]. The Si K-edge XANES spectra show that S hyperdoping in Si increases (decreased) the occupied (unoccupied) electronic density of states at/above the conduction-band-minimum. VB-PES spectra evidently reveal that the S-dopants not only form an impurity band deep within the band gap, giving rise to the sub-band gap absorption, but also cause the insulator-to-metal transition in S-hyperdoped Si samples. Based on the experimental results and the calculations by density functional theory, the chemical state of the S species and the formation of the S-dopant states in the band gap of Si are critical in determining the sub-band gap absorptance of hyperdoped Si samples. PMID:26098075

  20. Infrared absorption band in deformed qtz crystals analyzed by combining different microstructural methods

    NASA Astrophysics Data System (ADS)

    Stunitz, Holger; Thust, Anja; Behrens, Harald; Heilbronner, Renee; Kilian, Ruediger

    2016-04-01

    Natural single crystals of quartz have been experimentally deformed in two orientations: (1) normal to one prism-plane, (2) In O+ orientation at temperatures of 900 and 1000°C, pressures of 1.0 and 1.5 GPa, and strain rates of ~1 x 10-6s-1. The starting material is milky quartz, consisting of dry quartz (H2O contents of <150 H/106Si) with fluid inclusions (FI). During pressurization many FÍs decrepitate. Cracks heal and small neonate FÍs form, increasing the number of FÍs drastically. During subsequent deformation, the size of FÍs is further reduced (down to ~10 nm). Sample deformation occurs by dominant dislocation glide on selected slip systems, accompanied by some dynamic recovery. Strongly deformed regions show FTIR spectra with a pointed broad absorption band in the ~3400 cm-1 region as a superposition of molecular H2O bands and three discrete absorption bands (at 3367, 3400, and 3434 cm-1). In addition, there is a discrete absorption band at 3585 cm-1, which only occurs in deformed regions. The 3585 cm-1 band is reduced or even disappears after annealing. This band is polarized and represents structurally bound H, its H-content is estimated to be 1-3% of the total H2O-content and appears to be associated with dislocations. The H2O weakening effect in our FI-bearing natural quartz crystals is assigned to the processes of dislocation generation and multiplication at small FÍs. The deformation processes in these crystals represent a recycling of H2O between FÍs, dislocation generation at very small fluid inclusions, incorporation of structurally bound H into dislocation cores, and release of H2O from dislocations back into FÍs during recovery. Cracking and crack healing play an important role in the recycling process and imply a close interrelationship between brittle and crystal plastic deformation. The H2O weakening by this process is of a disequilibrium nature and thus depends on the amount of H2O available.

  1. Reassignment of the Iron (3) Absorption Bands in the Spectra of Mars

    NASA Technical Reports Server (NTRS)

    Sherman, D. M.

    1985-01-01

    Absorption features in the near-infrared and visible region reflectance spectra of Mars have been assigned to specific Fe (3+) crystal-field and o(2-) yields Fe(3+) charge transfer transitions. Recently, near-ultraviolet absorption spectra of iron oxides were obtained and the energies of o(2-) yields Fe(3+) charge-transfer (LMCT) transitions were determined from accurate SCF-X # alpha-SW molecular orbital calculations on (FeO6)(9-) and (FeO4)(5-) clusters. Both the theoretical and experimental results, together with existing data in the literature, show that some of the previous Fe(3+) band assignments in the spectra of Mars need to be revised. The theory of Fe(3+) spectra in minerals is discussed and applied to the spectrum of Mars.

  2. Near-infrared broad-band cavity enhanced absorption spectroscopy using a superluminescent light emitting diode.

    PubMed

    Denzer, W; Hamilton, M L; Hancock, G; Islam, M; Langley, C E; Peverall, R; Ritchie, G A D

    2009-11-01

    A fibre coupled near-infrared superluminescent light emitting diode that emits approximately 10 mW of radiation between 1.62 and 1.7 microm is employed in combination with a broad-band cavity enhanced spectrometer consisting of a linear optical cavity with mirrors of reflectivity approximately 99.98% and either a dispersive near-infrared spectrometer or a Fourier transform interferometer. Results are presented on the absorption of 1,3-butadiene, and sensitivities are achieved of 6.1 x 10(-8) cm(-1) using the dispersive spectrometer in combination with phase-sensitive detection, and 1.5 x 10(-8) cm(-1) using the Fourier transform interferometer (expressed as a minimum detectable absorption coefficient) over several minutes of acquisition time.

  3. Doping-Induced Absorption Bands in P3HT: Polarons and Bipolarons.

    PubMed

    Enengl, Christina; Enengl, Sandra; Pluczyk, Sandra; Havlicek, Marek; Lapkowski, Mieczyslaw; Neugebauer, Helmut; Ehrenfreund, Eitan

    2016-12-05

    In this work, we focus on the formation of different kinds of charge carriers such as polarons and bipolarons upon p-type doping (oxidation) of the organic semiconductor poly(3- hexylthiophene-2,5-diyl) (P3HT). We elucidate the cyclic voltammogram during oxidation of this polymer and present spectroscopic changes upon doping in the UV/Vis/near-IR range as well as in the mid-IR range. In the low-oxidation regime, two absorption bands related to sub-gap transitions appear, one in the UV/Vis range and another one in the mid-IR range. The UV/Vis absorption gradually decreases upon further doping while the mid-IR absorption shifts to lower energy. Additionally, electron paramagnetic resonance (EPR) measurements are performed, showing an increase of the EPR signal up to a certain doping level, which significantly decreases upon further doping. Furthermore, the absorption spectra in the UV/Vis range are analyzed in relation to the morphology (crystalline vs. amorphous) by using theoretical models. Finally, the calculated charge carriers from cyclic voltammogram are linked together with optical transitions as well as with the EPR signals upon p-type doping. We stress that our results indicate the formation of polarons at low doping levels and the existence of bipolarons at high doping levels. The presented spectroscopic data are an experimental evidence of the formation of bipolarons in P3HT.

  4. Collisional Induced Absorption (CIA) bands of CO2 and H2 measured in the IR spectral range

    NASA Astrophysics Data System (ADS)

    Stefani, S.; Piccioni, G.; Snels, M.; Adriani, A.; Grassi, D.

    2015-10-01

    In this paper we present the results on the Collisional Induced Absorption (CIA) bands of CO2 and H2 measured employing two different experimental setup. Each of them allows us to reproduce typical planetary conditions, at a pressure and temperature from 1 up to 50 bar and from 298 up to 500 K respectively. A detailed study on the temperature dependence of the CO2 CIA absorption bands will be presented.

  5. Study of sub band gap absorption of Sn doped CdSe thin films

    NASA Astrophysics Data System (ADS)

    Kaur, Jagdish; Rani, Mamta; Tripathi, S. K.

    2014-04-01

    The nanocrystalline thin films of Sn doped CdSe at different dopants concentration are prepared by thermal evaporation technique on glass substrate at room temperature. The effect of Sn doping on the optical properties of CdSe has been studied. A decrease in band gap value is observed with increase in Sn concentration. Constant photocurrent method (CPM) is used to study the absorption coefficient in the sub band gap region. Urbach energy has been obtained from CPM spectra which are found to increase with amount of Sn dopants. The refractive index data calculated from transmittance is used for the identification of oscillator strength and oscillator energy using single oscillator model which is found to be 7.7 and 2.12 eV, 6.7 and 2.5 eV for CdSe:Sn 1% and CdSe:Sn 5% respectively.

  6. Femtosecond supercontinuum generation in water in the vicinity of absorption bands.

    PubMed

    Dharmadhikari, J A; Steinmeyer, G; Gopakumar, G; Mathur, D; Dharmadhikari, A K

    2016-08-01

    We show that it is possible to overcome the perceived limitations caused by absorption bands in water so as to generate supercontinuum (SC) spectra in the anomalous dispersion regime that extend well beyond 2000 nm wavelength. By choosing a pump wavelength within a few hundred nanometers above the zero-dispersion wavelength of 1048 nm, initial spectral broadening extends into the normal dispersion regime and, in turn, the SC process in the visible strongly benefits from phase-matching and matching group velocities between dispersive radiation and light in the anomalous dispersion regime. Some of the SC spectra are shown to encompass two and a half octaves.

  7. Theoretical Modeling of Low Energy Electronic Absorption Bands in Reduced Cobaloximes

    PubMed Central

    Bhattacharjee, Anirban; Chavarot-Kerlidou, Murielle; Dempsey, Jillian L.; Gray, Harry B.; Fujita, Etsuko; Muckerman, James T.; Fontecave, Marc; Artero, Vincent; Arantes, Guilherme M.; Field, Martin J.

    2015-01-01

    The reduced Co(I) states of cobaloximes are powerful nucleophiles that play an important role in the hydrogen-evolving catalytic activity of these species. In this work we have analyzed the low energy electronic absorption bands of two cobaloxime systems experimentally and using a variety of density functional theory and molecular orbital ab initio quantum chemical approaches. Overall we find a reasonable qualitative understanding of the electronic excitation spectra of these compounds but show that obtaining quantitative results remains a challenging task. PMID:25113847

  8. Theoretical modeling of low-energy electronic absorption bands in reduced cobaloximes.

    PubMed

    Bhattacharjee, Anirban; Chavarot-Kerlidou, Murielle; Dempsey, Jillian L; Gray, Harry B; Fujita, Etsuko; Muckerman, James T; Fontecave, Marc; Artero, Vincent; Arantes, Guilherme M; Field, Martin J

    2014-10-06

    The reduced Co(I) states of cobaloximes are powerful nucleophiles that play an important role in the hydrogen-evolving catalytic activity of these species. In this work we analyze the low-energy electronic absorption bands of two cobaloxime systems experimentally and use a variety of density functional theory and molecular orbital ab initio quantum chemical approaches. Overall we find a reasonable qualitative understanding of the electronic excitation spectra of these compounds but show that obtaining quantitative results remains a challenging task.

  9. Theoretical modeling of low-energy electronic absorption bands in reduced cobaloximes

    SciTech Connect

    Bhattacharjee, Anirban; Chavarot-Kerlidou, Murielle; Dempsey, Jillian L.; Gray, Harry B.; Fujita, Etsuko; Muckerman, James T.; Fontecave, Marc; Artero, Vincent; Arantes, Guilherme M.; Field, Martin J.

    2014-08-11

    Here, we report that the reduced Co(I) states of cobaloximes are powerful nucleophiles that play an important role in the hydrogen-evolving catalytic activity of these species. In this work we have analyzed the low energy electronic absorption bands of two cobaloxime systems experimentally and using a variety of density functional theory and molecular orbital ab initio quantum chemical approaches. Overall we find a reasonable qualitative understanding of the electronic excitation spectra of these compounds but show that obtaining quantitative results remains a challenging task.

  10. Theoretical modeling of low-energy electronic absorption bands in reduced cobaloximes

    DOE PAGES

    Bhattacharjee, Anirban; Chavarot-Kerlidou, Murielle; Dempsey, Jillian L.; ...

    2014-08-11

    Here, we report that the reduced Co(I) states of cobaloximes are powerful nucleophiles that play an important role in the hydrogen-evolving catalytic activity of these species. In this work we have analyzed the low energy electronic absorption bands of two cobaloxime systems experimentally and using a variety of density functional theory and molecular orbital ab initio quantum chemical approaches. Overall we find a reasonable qualitative understanding of the electronic excitation spectra of these compounds but show that obtaining quantitative results remains a challenging task.

  11. Optimal Reflectance, Transmittance, and Absorptance Wavebands and Band Ratios for the Estimation of Leaf Chlorophyll Concentration

    NASA Technical Reports Server (NTRS)

    Carter, Gregory A.; Spiering, Bruce A.

    2000-01-01

    The present study utilized regression analysis to identify: wavebands and band ratios within the 400-850 nm range that could be used to estimate total chlorophyll concentration with minimal error; and simple regression models that were most effective in estimating chlorophyll concentrations were measured for two broadleaved species, a broadleaved vine, a needle-leaved conifer, and a representative of the grass family.Overall, reflectance, transmittance, and absorptance corresponded most precisely with chlorophyll concentration at wavelengths near 700 nm, although regressions were strong as well in the 550-625 nm range.

  12. The nature of splitting of fullerene C{sub 70} polarized absorption bands in liquid-crystal matrices

    SciTech Connect

    Aver`yanov, E.M.

    1994-06-01

    The recently discovered splitting of polarized electronic absorption bands of fullerene C{sub 70} in uniaxial liquid-crystal matrices is shown to result from the spectral dependence of the polarization of these bands relative to the molecular coordinate system. 9 refs.

  13. Absorption coefficients for the 6190-A CH4 band between 290 and 100 K with application to Uranus' atmosphere

    NASA Technical Reports Server (NTRS)

    Smith, Wm. Hayden; Conner, Charles P.; Baines, Kevin H.

    1990-01-01

    A novel laser intracavity photoacoustic spectroscopy method allowing high sample control accuracy due to the small sample volume required has been used to obtain absorption coefficients for the CH4 6190 A band as a function of temperature, from 290 to 100 K. The peak absorption coefficient is found to increase from 0.6 to 1.0/cm, and to be accompanied by significant band shape changes. When used to further constrain the Baines and Bergstrahl (1986) standard model of the Uranus atmosphere, the low-temperature data yield an excellent fit to the bandshape near the 6190 A band's minimum.

  14. Absorption coefficients for the 6190-A CH sub 4 band between 290 and 100 K with application to Uranus' atmosphere

    SciTech Connect

    Smith, WM.H.; Conner, C.P.; Baines, K.H. JPL, Pasadena, CA )

    1990-05-01

    A novel laser intracavity photoacoustic spectroscopy method allowing high sample control accuracy due to the small sample volume required has been used to obtain absorption coefficients for the CH{sub 4} 6190 A band as a function of temperature, from 290 to 100 K. The peak absorption coefficient is found to increase from 0.6 to 1.0/cm, and to be accompanied by significant band shape changes. When used to further constrain the Baines and Bergstrahl (1986) standard model of the Uranus atmosphere, the low-temperature data yield an excellent fit to the bandshape near the 6190 A band's minimum. 18 refs.

  15. Band tail absorption saturation in CdWO4 with 100 fs laser pulses.

    PubMed

    Laasner, R; Fedorov, N; Grigonis, R; Guizard, S; Kirm, M; Makhov, V; Markov, S; Nagirnyi, V; Sirutkaitis, V; Vasil'ev, A; Vielhauer, S; Tupitsyna, I A

    2013-06-19

    The decay kinetics of the excitonic emission of CdWO4 scintillators was studied under excitation by powerful 100 fs laser pulses in the band tail (Urbach) absorption region. A special imaging technique possessing both spatial and temporal resolution provided a unique insight into the Förster dipole-dipole interaction of self-trapped excitons, which is the main cause of the nonlinear quenching of luminescence in this material. In addition, the saturation of phonon-assisted excitonic absorption due to extremely short excitation pulses was discovered. A model describing the evolution of electronic excitations in the conditions of absorption saturation was developed and an earlier model of decay kinetics based on the Förster interaction was extended to include the saturation effect. Compared to the previous studies, a more accurate calculation yields 3.7 nm as the Förster interaction radius. It was shown that exciton-exciton interaction is the main source of scintillation nonproportionality in CdWO4. A quantitative description using a new model of nonproportionality was presented, making use of the corrected value of the Förster radius.

  16. Ultra-wideband microwave absorber by connecting multiple absorption bands of two different-sized hyperbolic metamaterial waveguide arrays

    PubMed Central

    Yin, Xiang; Long, Chang; Li, Junhao; Zhu, Hua; Chen, Lin; Guan, Jianguo; Li, Xun

    2015-01-01

    Microwave absorbers have important applications in various areas including stealth, camouflage, and antenna. Here, we have designed an ultra-broadband light absorber by integrating two different-sized tapered hyperbolic metamaterial (HMM) waveguides, each of which has wide but different absorption bands due to broadband slow-light response, into a unit cell. Both the numerical and experimental results demonstrate that in such a design strategy, the low absorption bands between high absorption bands with a single-sized tapered HMM waveguide array can be effectively eliminated, resulting in a largely expanded absorption bandwidth ranging from 2.3 to 40 GHz. The presented ultra-broadband light absorber is also insensitive to polarization and robust against incident angle. Our results offer a further step in developing practical artificial electromagnetic absorbers, which will impact a broad range of applications at microwave frequencies. PMID:26477740

  17. Thermally induced effect on sub-band gap absorption in Ag doped CdSe thin films

    NASA Astrophysics Data System (ADS)

    Kaur, Jagdish; Sharma, Kriti; Bharti, Shivani; Tripathi, S. K.

    2015-05-01

    Thin films of Ag doped CdSe have been prepared by thermal evaporation using inert gas condensation (IGC) method taking Argon as inert gas. The prepared thin films are annealed at 363 K for one hour. The sub-band gap absorption spectra in the as deposited and annealed thin films have been studied using constant photocurrent method (CPM). The absorption coefficient in the sub-band gap region is described by an Urbach tail in both as deposited and annealed thin films. The value of Urbach energy and number density of trap states have been calculated from the absorption coefficient in the sub-band gap region which have been found to increase after annealing treatment indicating increase in disorderness in the lattice. The energy distribution of the occupied density of states below Fermi level has also been studied using derivative procedure of absorption coefficient.

  18. Ultra-wideband microwave absorber by connecting multiple absorption bands of two different-sized hyperbolic metamaterial waveguide arrays

    NASA Astrophysics Data System (ADS)

    Yin, Xiang; Long, Chang; Li, Junhao; Zhu, Hua; Chen, Lin; Guan, Jianguo; Li, Xun

    2015-10-01

    Microwave absorbers have important applications in various areas including stealth, camouflage, and antenna. Here, we have designed an ultra-broadband light absorber by integrating two different-sized tapered hyperbolic metamaterial (HMM) waveguides, each of which has wide but different absorption bands due to broadband slow-light response, into a unit cell. Both the numerical and experimental results demonstrate that in such a design strategy, the low absorption bands between high absorption bands with a single-sized tapered HMM waveguide array can be effectively eliminated, resulting in a largely expanded absorption bandwidth ranging from 2.3 to 40 GHz. The presented ultra-broadband light absorber is also insensitive to polarization and robust against incident angle. Our results offer a further step in developing practical artificial electromagnetic absorbers, which will impact a broad range of applications at microwave frequencies.

  19. Total ozone and aerosol optical depths inferred from radiometric measurements in the Chappuis absorption band

    SciTech Connect

    Flittner, D.E.; Herman, B.M.; Thome, K.J.; Simpson, J.M.; Reagan, J.A. )

    1993-04-15

    A second-derivative smoothing technique, commonly used in inversion work, is applied to the problem of inferring total columnar ozone amounts and aerosol optical depths. The application is unique in that the unknowns (i.e., total columnar ozone and aerosol optical depth) may be solved for directly without employing standard inversion methods. It is shown, however, that by employing inversion constraints, better solutions are normally obtained. The current method requires radiometric measurements of total optical depth through the Chappuis ozone band. It assumes no a priori shape for the aerosol optical depth versus wavelength profile and makes no assumptions about the ozone amount. Thus, the method is quite versatile and able to deal with varying total ozone and various aerosol size distributions. The technique is applied first in simulation, then to 119 days of measurements taken in Tucson, Arizona, that are compared to TOMS values for the same dates. The technique is also applied to two measurements taken at Mauna Loa, Hawaii, for which Dobson ozone values are available in addition to the TOMS values, and the results agree to within 15%. It is also shown through simulations that additional information can be obtained from measurements outside the Chappuis band. This approach reduces the bias and spread of the estimates total ozone and is unique in that it uses measurements from both the Chappuis and Huggins absorption bands. 12 refs., 6 figs., 2 tabs.

  20. [Gastric cancer detection using kubelka-Munk spectral function of DNA and protein absorption bands].

    PubMed

    Li, Lan-quan; Wei, Hua-jiang; Guo, Zhou-yi; Yang, Hong-qin; Xie, Shu-sen; Chen, Xue-mei; Li, Li-bo; He, Bol-hua; Wu, Guo-yong; Lu, Jian-jun

    2009-09-01

    Differential diagnosis for epithelial tissues of normal human gastric, undifferentiation gastric adenocarcinoma, gastric squamous cell carcinomas, and poorly differentiated gastric adenocarcinoma were studied using the Kubelka-Munk spectral function of the DNA and protein absorption bands at 260 and 280 nm in vitro. Diffuse reflectance spectra of tissue were measured using a spectrophotometer with an integrating sphere attachment. The results of measurement showed that for the spectral range from 250 to 650 nm, pathological changes of gastric epithelial tissues induced that there were significant differences in the averaged value of the Kubelka-Munk function f(r infinity) and logarithmic Kubelka-Munk function log[f(r infinity)] of the DNA absorption bands at 260 nm between epithelial tissues of normal human stomach and human undifferentiation gastric cancer, between epithelial tissues of normal human stomach and human gastric squamous cell carcinomas, and between epithelial tissues of normal human stomach and human poorly differentiated cancer. Their differences were 68.5% (p < 0.05), 146.5% (p < 0.05), 282.4% (p < 0.05), 32.4% (p < 0.05), 56.00 (p < 0.05) and 83.0% (p < 0.05) respectively. And pathological changes of gastric epithelial tissues induced that there were significant differences in the averaged value of the Kubelka-Munk function f(r infinity) and logarithmic Kubelka-Munk function log[f(r infinity)] of the protein absorption bands at 280 nm between epithelial tissues of normal human stomach and human undifferentiation gastric cancer, between epithelial tissues of normal human stomach and human gastric squamous cell carcinomas, and between epithelial tissues of normal human stomach and human poorly differentiated cancer. Their differences were 86.8% (p < 0.05), 262.9% (p < 0.05), 660.1% (p < 0.05) and 34% (p < 0.05), 72. 2% (p < 0.05), 113.5% (p < 0.05) respectively. And pathological changes of gastric epithelial tissues induced that there were

  1. VARIABILITY OF WATER AND OXYGEN ABSORPTION BANDS IN THE DISK-INTEGRATED SPECTRA OF EARTH

    SciTech Connect

    Fujii, Yuka; Suto, Yasushi; Turner, Edwin L.

    2013-03-10

    We study the variability of major atmospheric absorption features in the disk-integrated spectra of Earth with future application to Earth-analogs in mind, concentrating on the diurnal timescale. We first analyze observations of Earth provided by the EPOXI mission, and find 5%-20% fractional variation of the absorption depths of H{sub 2}O and O{sub 2} bands, two molecules that have major signatures in the observed range. From a correlation analysis with the cloud map data from the Earth Observing Satellite (EOS), we find that their variation pattern is primarily due to the uneven cloud cover distribution. In order to account for the observed variation quantitatively, we consider a simple opaque cloud model, which assumes that the clouds totally block the spectral influence of the atmosphere below the cloud layer, equivalent to assuming that the incident light is completely scattered at the cloud top level. The model is reasonably successful, and reproduces the EPOXI data from the pixel-level EOS cloud/water vapor data. A difference in the diurnal variability patterns of H{sub 2}O and O{sub 2} bands is ascribed to the differing vertical and horizontal distribution of those molecular species in the atmosphere. On Earth, the inhomogeneous distribution of atmospheric water vapor is due to the existence of its exchange with liquid and solid phases of H{sub 2}O on the planet's surface on a timescale short compared with atmospheric mixing times. If such differences in variability patterns were detected in spectra of Earth-analogs, it would provide the information on the inhomogeneous composition of their atmospheres.

  2. Geometrical attenuation, frequency dependence of Q, and the absorption band problem

    NASA Astrophysics Data System (ADS)

    Morozov, Igor B.

    2008-10-01

    A geometrical attenuation model is proposed as an alternative to the conventional frequency-dependent attenuation law Q(f) = Q0(f/f0)η. The new model provides a straightforward differentiation between the geometrical and effective attenuation (Qe) which incorporates the intrinsic attenuation and small-scale scattering. Unlike the (Q0, η) description, the inversion procedure uses only the spectral amplitude data and does not rely on elaborate theoretical models or restrictive assumptions. Data from over 40 reported studies were transformed to the new parametrization. The levels of geometrical attenuation strongly correlate with crustal tectonic types and decrease with tectonic age. The corrected values of Qe are frequency-independent and generally significantly higher than Q0 and show no significant correlation with tectonic age. Several case studies were revisited in detail, with significant changes in the interpretations. The absorption-band and the `10-Hz transition' are not found in the corrected Qe data, and therefore, these phenomena are interpreted as related to geometrical attenuation. The absorption band could correspond to changes in the dominant mode content of the wavefield as the frequency changes from about 0.1 to 100 Hz. Alternatively, it could also be a pure artefact related to the power-law Q(f) paradigm above. The explicit separation of the geometrical and intrinsic attenuation achieves three goals: (1) it provides an unambiguous, assumption- and model-free description of attenuation, (2) it allows relating the observations to the basic physics and geology and (3) it simplifies the interpretation because of reduced emphasis on the apparent Q(f) dependence. The model also agrees remarkably well with the initial attempts for finite-difference short-period coda waveform modelling. Because of its consistency and direct link to the observations, the approach should also help in building robust and transportable coda magnitudes and in seismic

  3. Investigation of band gap narrowing in nitrogen-doped La2Ti2O7 with transient absorption spectroscopy.

    PubMed

    Yost, Brandon T; Cushing, Scott K; Meng, Fanke; Bright, Joeseph; Bas, Derek A; Wu, Nianqiang; Bristow, Alan D

    2015-12-14

    Doping a semiconductor can extend the light absorption range, however, it usually introduces mid-gap states, reducing the charge carrier lifetime. This report shows that doping lanthanum dititinate (La2Ti2O7) with nitrogen extends the valence band edge by creating a continuum of dopant states, increasing the light absorption edge from 380 nm to 550 nm without adding mid-gap states. The dopant states are experimentally resolved in the excited state by correlating transient absorption spectroscopy with a supercontinuum probe and DFT prediction. The lack of mid-gap states is further confirmed by measuring the excited state lifetimes, which reveal the shifted band edge only increased carrier thermalization rates to the band edge and not interband charge recombination under both ultraviolet and visible excitation. Terahertz (time-domain) spectroscopy also reveals that the conduction mechanism remains unchanged after doping, suggesting the states are delocalized.

  4. Band gap reduction in InNxSb1-x alloys: Optical absorption, k . P modeling, and density functional theory

    NASA Astrophysics Data System (ADS)

    Linhart, W. M.; Rajpalke, M. K.; Buckeridge, J.; Murgatroyd, P. A. E.; Bomphrey, J. J.; Alaria, J.; Catlow, C. R. A.; Scanlon, D. O.; Ashwin, M. J.; Veal, T. D.

    2016-09-01

    Using infrared absorption, the room temperature band gap of InSb is found to reduce from 174 (7.1 μm) to 85 meV (14.6 μm) upon incorporation of up to 1.13% N, a reduction of ˜79 meV/%N. The experimentally observed band gap reduction in molecular-beam epitaxial InNSb thin films is reproduced by a five band k . P band anticrossing model incorporating a nitrogen level, EN, 0.75 eV above the valence band maximum of the host InSb and an interaction coupling matrix element between the host conduction band and the N level of β = 1.80 eV. This observation is consistent with the presented results from hybrid density functional theory.

  5. Self-absorption theory applied to rocket measurements of the nitric oxide (1, 0) gamma band in the daytime thermosphere

    NASA Technical Reports Server (NTRS)

    Eparvier, F. G.; Barth, C. A.

    1992-01-01

    Observations of the UV fluorescent emissions of the NO (1, 0) and (0, 1) gamma bands in the lower-thermospheric dayglow, made with a sounding rocket launched on March 7, 1989 from Poker Flat, Alaska, were analyzed. The resonant (1, 0) gamma band was found to be attenuated below an altitude of about 120 km. A self-absorption model based on Holstein transmission functions was developed for the resonant (1, 0) gamma band under varying conditions of slant column density and temperature and was applied for the conditions of the rocket flight. The results of the model agreed with the measured attenuation of the band, indicating the necessity of including self-absorption theory in the analysis of satellite and rocket limb data of NO.

  6. Absorption band oscillator strengths of N2 transitions between 95.8 and 99.4 nm

    NASA Technical Reports Server (NTRS)

    Stark, G.; Smith, Peter L.; Huber, K. P.; Yoshino, K.; Stevens, M. H.; Ito, K.

    1992-01-01

    Molecular nitrogen plays a central role in the energetics of the earth's upper atmosphere and is the major constituent of the atmospheres of the planetary satellites Titan and Triton. This paper reports a new set of absorption oscillator strengths measured at higher resolution for seven bands in the 95.8-99.4 nm region. The results are compared with earlier, lower resolution absorption measurements, electron scattering measurements, and calculations based on a deperturbation analysis of the excited states.

  7. Absorption band III kinetics probe the picosecond heme iron motion triggered by nitric oxide binding to hemoglobin and myoglobin.

    PubMed

    Yoo, Byung-Kuk; Kruglik, Sergei G; Lamarre, Isabelle; Martin, Jean-Louis; Negrerie, Michel

    2012-04-05

    To study the ultrafast movement of the heme iron induced by nitric oxide (NO) binding to hemoglobin (Hb) and myoglobin (Mb), we probed the picosecond spectral evolution of absorption band III (∼760 nm) and vibrational modes (iron-histidine stretching, ν(4) and ν(7) in-plane modes) in time-resolved resonance Raman spectra. The time constants of band III intensity kinetics induced by NO rebinding (25 ps for hemoglobin and 40 ps for myoglobin) are larger than in Soret bands and Q-bands. Band III intensity kinetics is retarded with respect to NO rebinding to Hb and to Mb. Similarly, the ν((Fe-His)) stretching intensity kinetics are retarded with respect to the ν(4) and ν(7) heme modes and to Soret absorption. In contrast, band III spectral shift kinetics do not coincide with band III intensity kinetics but follows Soret kinetics. We concluded that, namely, the band III intensity depends on the heme iron out-of-plane position, as theoretically predicted ( Stavrov , S. S. Biopolymers 2004 , 74 , 37 - 40 ).

  8. Dual-band microwave absorption properties of metamaterial absorber composed of split ring resonator on carbonyl iron powder composites

    NASA Astrophysics Data System (ADS)

    Lim, Jun-Hee; Ryu, Yo-Han; Kim, Sung-Soo

    2015-05-01

    This study investigated the dual-band absorption properties of metamaterial absorbers composed of a split ring resonator (SRR) on a grounded magnetic substrate. Polymer composites of carbonyl iron powders (CIP) of high permeability and magnetic loss were used as the substrate material. Computational tools were used to model the interaction between electromagnetic waves and materials with the SRR structure. For perpendicular polarization with an electric field (E) perpendicular to the SRR gap, dualband absorption peaks are predicted in the simulation result of reflection loss. Magnetic resonance resulting from antiparallel currents between the SRR and the ground plane is observed at the frequencies of two absorption peaks. The first strong absorption peak at the lower frequency (3.3 GHz) is due to magnetic resonance at the wire part of the SRR. The second absorption peak at the higher frequency (7.2 GHz) is due to magnetic resonance at the SRR split gap. The decreased capacitance with increased gap spacing moves the second absorption frequency to higher frequencies, while the first absorption peak is invariant with gap spacing. In the case of dual gaps at the opposite sides of the SRR, a single absorption peak is predicted due to the elimination of low-frequency resonance. For parallel polarization with the E-field parallel to the SRR gap, a single absorption peak is predicted, corresponding to magnetic resonance at the SRR wire.[Figure not available: see fulltext.

  9. ESA Gaia and GRBs

    SciTech Connect

    Hudec, Rene; Simon, Vojtech; Hudec, Lukas

    2008-05-22

    Albeit focusing on astrometry, the ESA Gaia space mission will also provide spectrophotometry for all objects down to mag 20 over 5 years operation period. Typically 50 to 200 measurements per object including optical counterparts of celestial high-energy sources can be expected during this time interval. Also optical afterglows and optical transients of GRBs can be detected and investigated this way.

  10. ESA safety requirements

    NASA Astrophysics Data System (ADS)

    Tedeman, L.

    1988-10-01

    The ESA safety policy, designed to protect human life, investments, and the environment is outlined. A risk assessment procedure which recognizes the lack of objective statistical data is discussed. It considers the consequences, frequency, and probability of an undesirable hazardous event. This risk assessment is applied as an iterative process during all project phases.

  11. Planetary Exploration in ESA

    NASA Technical Reports Server (NTRS)

    Schwehm, Gerhard H.

    2005-01-01

    A viewgraph presentation on planetary exploration in the European Space Agency is shown. The topics include: 1) History of the Solar System Material; 2) ROSETTA: The Comet Mission; 3) A New Name For The Lander: PHILAE; 4) The Rosetta Mission; 5) Lander: Design Characteristics; 6) SMART-1 Mission; 7) MARS Express VENUS Express; 8) Planetary Exploration in ESA The Future.

  12. Band gap shift and the optical nonlinear absorption of sputtered ZnO-TiO2 films.

    PubMed

    Han, Yi-Bo; Han, Jun-Bo; Hao, Zhong-Hua

    2011-06-01

    ZnO-TiO2 composite films with different Zn/Ti atomic ratios were prepared with radio frequency reactive sputtering method. The Zn percentage composition (f(Zn)) dependent optical band gap and optical nonlinear absorption were investigated using the transmittance spectrum and the Z-scan technique, respectively. The results showed that composite films with f(Zn) in the range of 23.5%-88.3% are poor crystallized and their optical properties are anomalous which exhibit adjustable optical band gap and large optical nonlinear absorption. The optical absorption edge shifted to the blue wavelength direction with the increasing of f(Zn) and reached the minimum value of 285 nm for the sample with f(Zn) = 70.5%, which has the largest direct band gap of 4.30 eV. Further increasing of f(Zn) resulted in the red-shift of the optical absorption edge. The maximum optical nonlinear absorption coefficient of 1.5 x 10(3) cm/GW was also obtained for the same sample with f(Zn) = 70.5%, which is more than 40 times larger than those of pure TiO2 and ZnO films.

  13. Stratospheric observations of the attenuated solar irradiance in the Schumann-Runge band absorption region of molecular oxygen

    NASA Technical Reports Server (NTRS)

    Frederick, J. E.; Hudson, R. D.; Mentall, J. E.

    1981-01-01

    A spectrometer flown on the first Solar Absorption Balloon Experiment (SABE-1) observed the attenuated solar irradiance between 184 and 202 nm from an altitude near 40 km. These measurements provide a check on the absorption cross sections of molecular oxygen in the spectral region of the Schumann-Runge bands. Comparison of the measurements with calculations based on cross sections derived from laboratory data shows a general agreement although the irradiance measurements have large error bars near the centers of the absorption bands. The results imply that the 184-200 nm solar irradiance that penetrates to the stratosphere can be computed to an accuracy of + or - 30% or better by using presently available cross sections.

  14. Synthesis and photocatalytic activity of perovskite niobium oxynitrides with wide visible-light absorption bands.

    PubMed

    Siritanaratkul, Bhavin; Maeda, Kazuhiko; Hisatomi, Takashi; Domen, Kazunari

    2011-01-17

    Photocatalytic activities of perovskite-type niobium oxynitrides (CaNbO₂N, SrNbO₂N, BaNbO₂N, and LaNbON₂) were examined for hydrogen and oxygen evolution from water under visible-light irradiation. These niobium oxynitrides were prepared by heating the corresponding oxide precursors, which were synthesized using the polymerized complex method, for 15 h under a flow of ammonia. They possess visible-light absorption bands between 600-750 nm, depending on the A-site cations in the structures. The oxynitride CaNbO₂N, was found to be active for hydrogen and oxygen evolution from methanol and aqueous AgNO₃, respectively, even under irradiation by light at long wavelengths (λ<560 nm). The nitridation temperature dependence of CaNbO₂N was investigated and 1023 K was found to be the optimal temperature. At lower temperatures, the oxynitride phase is not adequately produced, whereas higher temperatures produce more reduced niobium species (e. g., Nb³(+) and Nb⁴(+)), which can act as electron-hole recombination centers, resulting in a decrease in activity.

  15. Microwave absorption behavior of a polyaniline magnetic composite in the X-band

    NASA Astrophysics Data System (ADS)

    Aphesteguy, J. C.; Damiani, A.; DiGiovanni, D.; Jacobo, S. E.

    2012-08-01

    The development of nanosized materials is a subject of considerable interest both for understanding of the fundamental properties of magnetic materials for new technological applications. Polyaniline, composites Fe3O4/(PANI) with conducting, magnetic and electromagnetic properties with different amounts of Fe3O4 were successfully prepared. The samples were structurally characterized by scanning electron microscopy (SEM), X-ray diffraction and transmission electron microscopy (TEM) and magnetically, with a superconducting quantum interference device (SQUID) magnetometer. In order to explore microwave-absorbing properties in X-band, the composite nanoparticles were mixed with an epoxy resin to be converted into a microwave-absorbing composite. Microwave behavior with different Fe3O4/(PANI)-epoxy resin ratio was studied using a microwave vector network analyzer (VNA) in the range 7.5 to 13 GHz. For a constant thickness of 1.5 mm, absorption increases with the magnetite contents in the composites and in the oriented samples by the application of a magnetic field.

  16. High resolution absorption cross-sections and band oscillator strengths of the Schumann-Runge bands of oxygen at 79 K

    NASA Technical Reports Server (NTRS)

    Yoshino, K.; Freeman, D. E.; Esmond, J. R.; Parkinson, W. H.

    1987-01-01

    Cross sections of O2 at 79 K have been obtained from photoabsorption measurements at various pressures throughout the wavelength region 179.3-198.0 nm with a 6.65-m photoelectric scanning spectrometer equipped with a 2400-lines/mm grating and having an instrumental width (FWHM) of 0.0013 nm. The measured absorption cross sections of the Schumann-Runge bands (12,0) through (2,0) are independent of the instrumental width. The measured cross-sections are presented graphically here and are available at wavenumber intervals of about 0.1/cm as numerical compilations stored on magnetic tape from the National Space Science Data Center, NASA/Goddard. Band oscillator strengths of these bands have been determined by direct numerical integration of the measured cross sections.

  17. Structural diversity of the 3-micron absorption band in Enceladus’ plume from Cassini VIMS: Insights into subsurface environmental conditions

    NASA Astrophysics Data System (ADS)

    Dhingra, Deepak; Hedman, Matthew M.; Clark, Roger N.

    2015-11-01

    Water ice particles in Enceladus’ plume display their diagnostic 3-micron absorption band in Cassini VIMS data. These near infrared measurements of the plume also exhibit noticeable variations in the character of this band. Mie theory calculations reveal that the shape and location of the 3-micron band are controlled by a number of environmental and structural parameters. Hence, this band provides important insights into the properties of the water ice grains and about the subsurface environmental conditions under which they formed. For example, the position of the 3-micron absorption band minimum can be used to distinguish between crystalline and amorphous forms of water ice and to constrain the formation temperature of the ice grains. VIMS data indicates that the water ice grains in the plume are dominantly crystalline which could indicate formation temperatures above 113 K [e.g. 1, 2]. However, there are slight (but observable) variations in the band minimum position and band shape that may hint at the possibility of varying abundance of amorphous ice particles within the plume. The modeling results further indicate that there are systematic shifts in band minimum position with temperature for any given form of ice but the crystalline and amorphous forms of water ice are still distinguishable at VIMS spectral resolution. Analysis of the eruptions from individual source fissures (tiger stripes) using selected VIMS observations reveal differences in the 3-micron band shape that may reflect differences in the size distributions of the water ice particles along individual fissures. Mie theory models suggest that big ice particles (>3 micron) may be an important component of the plume.[1] Kouchi, A., T. Yamamoto, T. Kozasa, T. Kuroda, and J. M. Greenberg (1994) A&A, 290, 1009-1018 [2] Mastrapa, R. M. E., W. M. Grundy, and M. S. Gudipati (2013) in M. S. Gudipati and J. Castillo-Rogez (Eds.), The Science of Solar System Ices, pp. 371.

  18. ECOM - ESA's cost modelling

    NASA Astrophysics Data System (ADS)

    Fatelnig, Peter K.

    1996-01-01

    ESA, as an international procurement agency dealing with more than 1200 companies at the same time, must have the ability to assess the price for a product independently from other sources. Especially in the today's environment of flat or even declining budgets ESA has to ensure the value of the contributions coming from their member states. The paper presents a software tool developed by the Cost Analysis Division of ESTEC/ESA, which fits exactly the need for precise and retracable cost estimates for space business projects and components. As an introduction the driving needs and basic cost estimation techniques are presented. ECOM was conceived as a tool for independent price assessment and cost estimation. The gem within ECOM is the database, it contains historical data from ESA projects. The items are grouped in classes and the available data comprises the cost breakdown and the technical description, which are the main performance parameter, number of models, design status and beside the comments, also pictures are available. On the estimate part of ECOM it features all the well-known cost estimation techniques, like estimating using analogy, cost estimating relationship, parametric cost modelling, and includes links to commercial products (PCM, Price-H) as well. ECOM is capable of escalating for any given economical condition and any member state. To prepare reliable prize estimates, the cost analysts need the product tree, the work-package description, the technical description and the HW-matrix. The paper shows examples for the important steps of producing an estimate and is enhanced with authentical screen prints. ECOM is used by the Cost Analysis Division as an expert tool for professional cost estimation for space business projects.

  19. Airborne imaging spectrometer data of the Ruby Mountains, Montana: Mineral discrimination using relative absorption band-depth images

    USGS Publications Warehouse

    Crowley, J.K.; Brickey, D.W.; Rowan, L.C.

    1989-01-01

    Airborne imaging spectrometer data collected in the near-infrared (1.2-2.4 ??m) wavelength range were used to study the spectral expression of metamorphic minerals and rocks in the Ruby Mountains of southwestern Montana. The data were analyzed by using a new data enhancement procedure-the construction of relative absorption band-depth (RBD) images. RBD images, like bandratio images, are designed to detect diagnostic mineral absorption features, while minimizing reflectance variations related to topographic slope and albedo differences. To produce an RBD image, several data channels near an absorption band shoulder are summed and then divided by the sum of several channels located near the band minimum. RBD images are both highly specific and sensitive to the presence of particular mineral absorption features. Further, the technique does not distort or subdue spectral features as sometimes occurs when using other data normalization methods. By using RBD images, a number of rock and soil units were distinguished in the Ruby Mountains including weathered quartz - feldspar pegmatites, marbles of several compositions, and soils developed over poorly exposed mica schists. The RBD technique is especially well suited for detecting weak near-infrared spectral features produced by soils, which may permit improved mapping of subtle lithologic and structural details in semiarid terrains. The observation of soils rich in talc, an important industrial commodity in the study area, also indicates that RBD images may be useful for mineral exploration. ?? 1989.

  20. Absolute infrared vibrational band intensities of molecular ions determined by direct laser absorption spectroscopy in fast ion beams

    SciTech Connect

    Keim, E.R.; Polak, M.L.; Owrutsky, J.C.; Coe, J.V.; Saykally, R.J. )

    1990-09-01

    The technique of direct laser absorption spectroscopy in fast ion beams has been employed for the determination of absolute integrated band intensities ({ital S}{sup 0}{sub {ital v}}) for the {nu}{sub 3} fundamental bands of H{sub 3}O{sup +} and NH{sup +}{sub 4}. In addition, the absolute band intensities for the {nu}{sub 1} fundamental bands of HN{sup +}{sub 2} and HCO{sup +} have been remeasured. The values obtained in units of cm{sup {minus}2} atm{sup {minus}1} at STP are 1880(290) and 580(90) for the {nu}{sub 1} fundamentals of HN{sup +}{sub 2} and HCO{sup +}, respectively; and 4000(800) and 1220(190) for the {nu}{sub 3} fundamentals of H{sub 3}O{sup +} and NH{sup +}{sub 4}, respectively. Comparisons with {ital ab} {ital initio} results are presented.

  1. Mapping atomic and diffuse interstellar band absorption across the Magellanic Clouds and the Milky Way

    NASA Astrophysics Data System (ADS)

    Bailey, Mandy; van Loon, Jacco Th.; Sarre, Peter J.; Beckman, John E.

    2015-12-01

    Diffuse interstellar bands (DIBs) trace warm neutral and weakly ionized diffuse interstellar medium (ISM). Here we present a dedicated, high signal-to-noise spectroscopic survey of two of the strongest DIBs, at 5780 and 5797 Å, in optical spectra of 666 early-type stars in the Small and Large Magellanic Clouds, along with measurements of the atomic Na I D and Ca II K lines. The resulting maps show for the first time the distribution of DIB carriers across large swathes of galaxies, as well as the foreground Milky Way ISM. We confirm the association of the 5797 Å DIB with neutral gas, and the 5780 Å DIB with more translucent gas, generally tracing the star-forming regions within the Magellanic Clouds. Likewise, the Na I D line traces the denser ISM whereas the Ca II K line traces the more diffuse, warmer gas. The Ca II K line has an additional component at ˜200-220 km s-1 seen towards both Magellanic Clouds; this may be associated with a pan-Magellanic halo. Both the atomic lines and DIBs show sub-pc-scale structure in the Galactic foreground absorption; the 5780 and 5797 Å DIBs show very little correlation on these small scales, as do the Ca II K and Na I D lines. This suggests that good correlations between the 5780 and 5797 Å DIBs, or between Ca II K and Na I D, arise from the superposition of multiple interstellar structures. Similarity in behaviour between DIBs and Na I in the Small Magellanic Cloud (SMC), Large Magellanic Cloud (LMC) and Milky Way suggests the abundance of DIB carriers scales in proportion to metallicity.

  2. The absorption coefficient of the liquid N2 2.15-micron band and application to Triton

    NASA Technical Reports Server (NTRS)

    Grundy, William M.; Fink, Uwe

    1991-01-01

    The present measurements of the temperature dependence exhibited by the liquid N2 2.15-micron 2-0 collision-induced band's absorption coefficient and integrated absorption show the latter to be smaller than that of the N2 gas, and to decrease with decreasing temperature. Extrapolating this behavior to Triton's nominal surface temperature yields a new estimate of the N2-ice grain size on the Triton south polar cap; a mean N2 grain size of 0.7-3.0 cm is consistent with grain growth rate calculation results.

  3. X-ray absorption and reflection as probes of the GaN conduction bands: Theory and experiments

    SciTech Connect

    Lambrecht, W.R.L.; Rashkeev, S.N.; Segall, B.

    1997-04-01

    X-ray absorption measurements are a well-known probe of the unoccupied states in a material. The same information can be obtained by using glancing angle X-ray reflectivity. In spite of several existing band structure calculations of the group III nitrides and previous optical studies in UV range, a direct probe of their conduction band densities of states is of interest. The authors performed a joint experimental and theoretical investigation using both of these experimental techniques for wurtzite GaN.

  4. Detection of metal stress in boreal forest species using the 0.67-micron chlorophyll absorption band

    NASA Technical Reports Server (NTRS)

    Singhroy, Vernon H.; Kruse, Fred A.

    1991-01-01

    Several recent studies have shown that a shift of the red-edge inflection near 0.70 micron in vegetation reflectance spectra is an indicator of metal stress, partially attributable to changes in chlorophyll concentration. This 'red-edge shift', however, is difficult to detect and has been reported both toward longer (red) and shorter (blue) wavelengths. Our work demonstrates that direct measurement of the depth and width of the chlorophyll absorption band at 0.67 micron using digital feature extraction and absorption band characterization procedures developed for the analysis of mineral spectra is a more consistent indicator of metal stress. Additionally, the magnitude of these parameters is generally greater than that of the red edge shift and thus should be more amenable to detection and mapping using field and aircraft spectrometers.

  5. Theoretical study of electronic absorption spectroscopy of propadienylidene molecule vis-â-vis the observed diffuse interstellar bands

    NASA Astrophysics Data System (ADS)

    Reddy, Samala Nagaprasad; Mahapatra, S.

    2012-07-01

    Observation of broad and diffuse interstellar bands (DIBs) at 4881 Å and 5440 Å assigned to the optical absorption spectrum of Y-shaped propadienylidene (H2Cdbnd Cdbnd C:) molecule is theoretically examined in this paper. This molecule apparently absorbs in the same wavelength region as the observed DIBs and was suggested to be a potential carrier of these DIBs. This assignment mostly relied on the experimental data from radioastronomy and laboratory measurements. Motivated by these available experimental data we attempt here a theoretical study and investigate the detailed electronic structure and nuclear dynamics underlying the electronic absorption bands of propadienylidene molecule. Our results show that this molecule indeed absorbs in the wavelength region of the recorded DIBs. Strong nonadiabatic coupling between its energetically low-lying electronic states plays major role, initiates ultrafast internal conversion and contributes to the spectral broadening. Theoretical findings are finally compared with the available experimental and theoretical data and discussed in connection with the recorded DIBs.

  6. First detection of ionized helium absorption lines in infrared K band spectra of O-type stars

    NASA Technical Reports Server (NTRS)

    Conti, Peter S.; Block, David L.; Geballe, T. R.; Hanson, Margaret M.

    1993-01-01

    We have obtained high SNR, moderate-resolution K band spectra of two early O-type main sequence stars, HD 46150 O5 V, and HD 46223 O4 V, in the Rosette Nebula. We report the detection, for the first time, of the 2.189 micron He II line in O-type stars. Also detected is the 2.1661 micron Br-gamma line in absorption. The 2.058 micron He I line appears to be present in absorption in both stars, although its appearance at our resolution is complicated by atmospheric features. These three lines can form the basis for a spectral classification system for hot stars in the K band that may be used at infrared wavelengths to elucidate the nature of those luminous stars in otherwise obscured H II and giant H II regions.

  7. [Generation of reactive oxygen species in water under exposure of visible or infrared irradiation at absorption band of molecular oxygen].

    PubMed

    Gudkov, S V; Karp, O E; Garmash, S A; Ivanov, V E; Chernikov, A V; Manokhin, A A; Astashev, M E; Iaguzhinskiĭ, L S; Bruskov, V I

    2012-01-01

    It is found that in bidistilled water saturated with oxygen hydrogen peroxide and hydroxyl radicals are formed under the influence of visible and infrared radiation in the absorption bands of molecular oxygen. Formation of reactive oxygen species (ROS) occurs under the influence of both solar and artificial light sourses, including the coherent laser irradiation. The oxygen effect, i.e. the impact of dissolved oxygen concentration on production of hydrogen peroxide induced by light, is detected. It is shown that the visible and infrared radiation in the absorption bands of molecular oxygen leads to the formation of 8-oxoguanine in DNA in vitro. Physicochemical mechanisms of ROS formation in water when exposed to visible and infrared light are studied, and the involvement of singlet oxygen and superoxide anion radicals in this process is shown.

  8. a Theoretical Model for Wide-Band Infrared-Absorption Molecular Spectra at any Pressure: Fiction or Reality?

    NASA Astrophysics Data System (ADS)

    Buldyreva, Jeanna; Vander Auwera, Jean

    2014-06-01

    Various atmospheric applications require modeling of infrared absorption by the main atmospheric species in wide ranges of frequencies, pressures and temperatures. For different pressure regimes, different mechanisms are responsible for the observed intensities of vibration-rotation line manifolds, and the structure of the bands changes drastically when going from low to high densities. Therefore, no universal theoretical model exists presently to interpret simultaneously collapsed band-shapes observed at very high pressures and isolated-line shapes recorded in sub-atmospheric regimes. Using CO_2 absorption spectra as an example, we introduce some improvements in the non-Markovian Energy-Corrected Sudden model, developed for high-density spectra of arbitrary tensorial rank and generalized recently to parallel and perpendicular infrared absorption bands, and test the applicability of this approach for the case of nearly Doppler pressure regime via comparisons with recently recorded experimental intensities. J.V. Buldyreva and L. Bonamy, Phys. Rev. A 60(1), 370-376 (1999). J. Buldyreva and L. Daneshvar, J. Chem. Phys. 139, 164107 (2013). L. Daneshvar, T. Földes, J. Buldyreva, J. Vander Auwera, J. Quant. Spectrosc. Radiat. Transfer 2014 (to be submitted).

  9. Wideband enhancement of infrared absorption in a direct band-gap semiconductor by using nonabsorptive pyramids.

    PubMed

    Dai, Weitao; Yap, Daniel; Chen, Gang

    2012-07-02

    Efficient trapping of the light in a photon absorber or a photodetector can improve its performance and reduce its cost. In this paper we investigate two designs for light-trapping in application to infrared absorption. Our numerical simulations demonstrate that nonabsorptive pyramids either located on top of an absorbing film or having embedded absorbing rods can efficiently enhance the absorption in the absorbing material. A spectrally averaged absorptance of 83% is achieved compared to an average absorptance of 28% for the optimized multilayer structure that has the same amount of absorbing material. This enhancement is explained by the coupled-mode theory. Similar designs can also be applied to solar cells.

  10. ESA SnowLab project

    NASA Astrophysics Data System (ADS)

    Wiesmann, Andreas; Caduff, Rafael; Frey, Othmar; Werner, Charles

    2016-04-01

    Retrieval of the snow water equivalaent (SWE) from passive microwave observations dates back over three decades to initial studies made using the first operational radiometers in space. However, coarse spatial resolution (25 km) is an acknowledged limitation for the application of passive microwave measurements. The natural variability of snow cover itself is also notable; properties such as stratigraphy and snow microstructure change both spatially and over time, affecting the microwave signature. To overcome this deficit, the satellite mission COld REgions Hydrology High-resolution Observatory (CoReH2O) was proposed to the European Space Agency (ESA) in 2005 in response to the call for Earth Explorer 7 candidate missions. CoReH2O was a dual frequency (X- and Ku-band) SAR mission aimed to provide maps of SWE over land and snow accumulation on glaciers at a spatial resolution of 200 to 500 meters with an unprecedented accuracy. Within the frame of preparatory studies for CoReH2O Phase A, ESA undertook several research initiatives from 2009 to 2013 to study the mission concept and capabilities of the proposed sensor. These studies provided a wealth of information on emission and backscattering signatures of natural snow cover, which can be exploited to study new potential mission concepts for retrieval of snow cover properties and other elements of the cryosphere. Currently data related to multi-frequency, multi-polarisation, multitemporal of active and passive microwave measurements are still not available. In addition, new methods related to e.g. tomography are currently under development and need to be tested with real data. Also, the potential of interferometric and polarimetric measurements of the snow cover and its possible impact for novel mission/retrieval concepts must be assessed. . The objective of the SnowLab activity is to fill this gap and complement these datasets from earlier campaigns by acquiring a comprehensive multi-frequency, multi

  11. Wide angle and narrow-band asymmetric absorption in visible and near-infrared regime through lossy Bragg stacks

    PubMed Central

    Shu, Shiwei; Zhan, Yawen; Lee, Chris; Lu, Jian; Li, Yang Yang

    2016-01-01

    Absorber is an important component in various optical devices. Here we report a novel type of asymmetric absorber in the visible and near-infrared spectrum which is based on lossy Bragg stacks. The lossy Bragg stacks can achieve near-perfect absorption at one side and high reflection at the other within the narrow bands (several nm) of resonance wavelengths, whereas display almost identical absorption/reflection responses for the rest of the spectrum. Meanwhile, this interesting wavelength-selective asymmetric absorption behavior persists for wide angles, does not depend on polarization, and can be ascribed to the lossy characteristics of the Bragg stacks. Moreover, interesting Fano resonance with easily tailorable peak profiles can be realized using the lossy Bragg stacks. PMID:27251768

  12. Annealing-induced optical and sub-band-gap absorption parameters of Sn-doped CdSe thin films

    NASA Astrophysics Data System (ADS)

    Kaur, Jagdish; Tripathi, S. K.

    2016-01-01

    Thin films of Sn-doped CdSe were prepared by thermal evaporation onto glass substrates in an argon gas atmosphere and annealed at different temperatures. Structural evaluation of the films was carried out using X-ray diffraction and their stoichiometry studied by energy-dispersive X-ray analysis. The films exhibit a preferred orientation along the hexagonal direction of CdSe. The optical transmittance of the films shows a red shift of the absorption edge with annealing. The fundamental absorption edge corresponds to a direct energy gap with a temperature coefficient of 3.34 × 10-3 eV K-1. The refractive index, optical conductivity and real and imaginary parts of the dielectric constants were found to increase after annealing. The sub-band gap absorption coefficient was evaluated using the constant photocurrent method. It varies exponentially with photon energy. The Urbach energy, the density of defect states, and the steepness of the density of localized states were evaluated from the sub-band-gap absorption.

  13. The C2H, C2, and CN electronic absorption bands in the carbon star HD 19557

    NASA Technical Reports Server (NTRS)

    Goebel, J. H.; Bregman, J. D.; Cooper, D. M.; Goorvitch, D.; Langhoff, S. R.; Witteborn, F. C.

    1983-01-01

    Infrared spectrophotometry of the R-type carbon star HD 19557 is presented. Two unusual spectroscopic features are seen: a 3.1 micron band is lacking and a 2.8 micron band is present. Identifications are proposed for three previously unreported stellar absorption bands with electronic sequences of C2, CN, and C2H. The latter is proposed to be responsible for the 2.8 micron feature. The atmospheric structure of the star is studied with synthetic spectra, and an effective temperature between 2600 K and 3000 K is suggested. No SiC emission is seen at 11.3 microns, indicating that grain formation is not a viable process around the star. The lack of dust in R stars may suggest a salient difference between R and N types.

  14. Analysis of airborne imaging spectrometer data for the Ruby Mountains, Montana, by use of absorption-band-depth images

    NASA Technical Reports Server (NTRS)

    Brickey, David W.; Crowley, James K.; Rowan, Lawrence C.

    1987-01-01

    Airborne Imaging Spectrometer-1 (AIS-1) data were obtained for an area of amphibolite grade metamorphic rocks that have moderate rangeland vegetation cover. Although rock exposures are sparse and patchy at this site, soils are visible through the vegetation and typically comprise 20 to 30 percent of the surface area. Channel averaged low band depth images for diagnostic soil rock absorption bands. Sets of three such images were combined to produce color composite band depth images. This relative simple approach did not require extensive calibration efforts and was effective for discerning a number of spectrally distinctive rocks and soils, including soils having high talc concentrations. The results show that the high spectral and spatial resolution of AIS-1 and future sensors hold considerable promise for mapping mineral variations in soil, even in moderately vegetated areas.

  15. Time-Resolved IR-Absorption Spectroscopy of Hot-Electron Dynamics in Satellite and Upper Conduction Bands in GaP

    NASA Technical Reports Server (NTRS)

    Cavicchia, M. A.; Alfano, R. R.

    1995-01-01

    The relaxation dynamics of hot electrons in the X6 and X7 satellite and upper conduction bands in GaP was directly measured by femtosecond UV-pump-IR-probe absorption spectroscopy. From a fit to the induced IR-absorption spectra the dominant scattering mechanism giving rise to the absorption at early delay times was determined to be intervalley scattering of electrons out of the X7 upper conduction-band valley. For long delay times the dominant scattering mechanism is electron-hole scattering. Electron transport dynamics of the upper conduction band of GaP has been time resolved.

  16. ESA's satellite communications programme

    NASA Astrophysics Data System (ADS)

    Bartholome, P.

    1985-02-01

    The developmental history, current status, and future plans of the ESA satellite-communications programs are discussed in a general survey and illustrated with network diagrams and maps. Consideration is given to the parallel development of national and European direct-broadcast systems and telecommunications networks, the position of the European space and electronics industries in the growing world market, the impact of technological improvements (both in satellite systems and in ground-based networks), and the technological and commercial advantages of integrated space-terrestrial networks. The needs for a European definition of the precise national and international roles of satellite communications, for maximum speed in implementing such decisions (before the technology becomes obsolete), and for increased cooperation and standardization to assure European equipment manufacturers a reasonable share of the market are stressed.

  17. Sub-nanometer linewidth perfect absorption in visible band induced by Bloch surface wave

    NASA Astrophysics Data System (ADS)

    Cong, Jiawei; Liu, Wenxing; Zhou, Zhiqiang; Ren, Naifei; Ding, Guilin; Chen, Mingyang; Yao, Hongbing

    2016-12-01

    We demonstrate the unity absorption of visible light with an ultra-narrow 0.1 nm linewidth. It arises from the Bloch surface wave resonance in alternating TiO2/SiO2 multilayers. The total absorption and narrow linewidth are explained from the radiative and absorptive damping, which are quantitatively determined by the temporal coupled mode theory. When a silver film with proper thickness is added to the absorber, the perfect absorption is achieved with only 3 structural bilayers, in contrast with 8 bilayers required without Ag. Furthermore, significant field enhancement and an ultrahigh 2600/RIU sensing figure-of-merit are simultaneously obtained at resonance, which might facilitate applications in nonlinear optical devices and high resolution refractive index sensing.

  18. Real-time monitoring of reactive species in downstream etch reactor by VUV broad-band absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Soriano, R.; Vallier, L.; Cunge, G.; Sadeghi, N.

    2016-09-01

    Plasma etching of nanometric size, high aspect-ratio structures is more challenging at each new technological node. Remote plasmas are beginning to find use when damages on nanostructures by ion bombardment become critical or when etching with high selectivity on different materials present on the wafer is necessary (i . e . tungsten oxide etching with fluorine and hydrogen containing plasmas in remote reactor from AMAT). Furthermore, it is expected that downstream plasma will replace many wet chemical etching processes to alleviate the issue of pattern collapses caused by capillary forces when nanometer size high aspect ratio structures are immersed in liquids. In these downstream plasmas, radicals are the main active species and a control of their density is of prime importance. Most of gases used and radicals produced in etching plasmas (HBr, BrCl, Br2, NF3, CH2F2,...) have strong absorption bands in the vacuum UV spectral region and we have shown that very low concentration of these species can be detected by VUV absorption. We have recently improved the technique by using a VUV CCD camera, instead of the PMT, which render possible the Broad-Band absorption spectroscopy in the 120-200 nm range, with a deuterium lamp, or a laser produced xenon arc lamp as light source. The multi-spectral detection ability of the CCD reduces the acquisition time to less than 1 second and can permit the real time control of the process control.

  19. Ground-based Photon Path Measurements from Solar Absorption Spectra of the O2 A-band

    NASA Technical Reports Server (NTRS)

    Yang, Z.; Wennberg, P. O.; Cageao, R. P.; Pongetti, T. J.; Toon, G. C.; Sander, S. P.

    2005-01-01

    High-resolution solar absorption spectra obtained from Table Mountain Facility (TMF, 34.38degN, 117.68degW, 2286 m elevation) have been analyzed in the region of the O2 A-band. The photon paths of direct sunlight in clear sky cases are retrieved from the O2 absorption lines and compared with ray-tracing calculations based on the solar zenith angle and surface pressure. At a given zenith angle, the ratios of retrieved to geometrically derived photon paths are highly precise (approx.0.2%), but they vary as the zenith angle changes. This is because current models of the spectral lineshape in this band do not properly account for the significant absorption that exists far from the centers of saturated lines. For example, use of a Voigt function with Lorentzian far wings results in an error in the retrieved photon path of as much as 5%, highly correlated with solar zenith angle. Adopting a super-Lorentz function reduces, but does not completely eliminate this problem. New lab measurements of the lineshape are required to make further progress.

  20. Semi-Empirical Validation of the Cross-Band Relative Absorption Technique for the Measurement of Molecular Mixing Ratios

    NASA Technical Reports Server (NTRS)

    Pliutau, Denis; Prasad, Narasimha S

    2013-01-01

    Studies were performed to carry out semi-empirical validation of a new measurement approach we propose for molecular mixing ratios determination. The approach is based on relative measurements in bands of O2 and other molecules and as such may be best described as cross band relative absorption (CoBRA). . The current validation studies rely upon well verified and established theoretical and experimental databases, satellite data assimilations and modeling codes such as HITRAN, line-by-line radiative transfer model (LBLRTM), and the modern-era retrospective analysis for research and applications (MERRA). The approach holds promise for atmospheric mixing ratio measurements of CO2 and a variety of other molecules currently under investigation for several future satellite lidar missions. One of the advantages of the method is a significant reduction of the temperature sensitivity uncertainties which is illustrated with application to the ASCENDS mission for the measurement of CO2 mixing ratios (XCO2). Additional advantages of the method include the possibility to closely match cross-band weighting function combinations which is harder to achieve using conventional differential absorption techniques and the potential for additional corrections for water vapor and other interferences without using the data from numerical weather prediction (NWP) models.

  1. Method for improving terahertz band absorption spectrum measurement accuracy using noncontact sample thickness measurement.

    PubMed

    Li, Zhi; Zhang, Zhaohui; Zhao, Xiaoyan; Su, Haixia; Yan, Fang; Zhang, Han

    2012-07-10

    The terahertz absorption spectrum has a complex nonlinear relationship with sample thickness, which is normally measured mechanically with limited accuracy. As a result, the terahertz absorption spectrum is usually determined incorrectly. In this paper, an iterative algorithm is proposed to accurately determine sample thickness. This algorithm is independent of the initial value used and results in convergent calculations. Precision in sample thickness can be improved up to 0.1 μm. A more precise absorption spectrum can then be extracted. By comparing the proposed method with the traditional method based on mechanical thickness measurements, quantitative analysis experiments on a three-component amino acid mixture shows that the global error decreased from 0.0338 to 0.0301.

  2. Absorption and emission line shapes in the O2 atmospheric bands - Theoretical model and limb viewing simulations

    NASA Technical Reports Server (NTRS)

    Abreu, Vincent J.; Bucholtz, A.; Hays, P. B.; Ortland, D.; Skinner, W. R.

    1989-01-01

    A multiple scattering radiative transfer model has been developed to carry out a line-by-line calculation of the absorption and emission limb measurements that will be made by the High Resolution Doppler Imager to be flown on the Upper Atmosphere Research Satellite. The multiple scattering model uses the doubling and adding methods to solve the radiative transfer equation, modified to take into account a spherical inhomogeneous atmosphere. Representative absorption and emission line shapes in the O2 1Sigma(+)g - 3Sigma(-)g atmospheric bands (A,B, and gamma) and their variation with altitude are presented. The effects of solar zenith angle, aerosol loading, surface albedo, and cloud height on the line shapes are also discussed.

  3. Iron-absorption band analysis for the discrimination of iron-rich zones

    NASA Technical Reports Server (NTRS)

    Rowan, L. C. (Principal Investigator)

    1972-01-01

    The author has identified the following significant results. Analysis of ERTS-1 images of Nevada has followed two courses: comparative lineament mapping and spectral reflectance evaluation. The comparative lineament mapping was conducted by mapping lineaments on 9 x 9 inch prints of MSS bands 5 and 7, transferring the data to a base map, and comparing the results with existing geologic maps. The most significant results are that lineaments are more numerous on the band 7 images, and approximately 100 percent more were mapped than appear on existing maps. Geologic significance of these newly mapped lineaments will not be known until they are checked in the field: many are probably faults. Spectral analysis has been limited to visual comparison among the four MSS bands. In general, higher scene contrast is shown in the near infrared bands (6 and 7) than in the visible wavelength bands (4 and 5). The economic implications of these results derive chiefly from the greater efficiency that can be obtained by using near infrared as well as visible wavelength images.

  4. Signatures of a conical intersection in photofragment distributions and absorption spectra: Photodissociation in the Hartley band of ozone

    SciTech Connect

    Picconi, David; Grebenshchikov, Sergy Yu.

    2014-08-21

    Photodissociation of ozone in the near UV is studied quantum mechanically in two excited electronic states coupled at a conical intersection located outside the Franck-Condon zone. The calculations, performed using recent ab initio PESs, provide an accurate description of the photodissociation dynamics across the Hartley/Huggins absorption bands. The observed photofragment distributions are reproduced in the two electronic dissociation channels. The room temperature absorption spectrum, constructed as a Boltzmann average of many absorption spectra of rotationally excited parent ozone, agrees with experiment in terms of widths and intensities of diffuse structures. The exit channel conical intersection contributes to the coherent broadening of the absorption spectrum and directly affects the product vibrational and translational distributions. The photon energy dependences of these distributions are strikingly different for fragments created along the adiabatic and the diabatic paths through the intersection. They can be used to reverse engineer the most probable geometry of the non-adiabatic transition. The angular distributions, quantified in terms of the anisotropy parameter β, are substantially different in the two channels due to a strong anticorrelation between β and the rotational angular momentum of the fragment O{sub 2}.

  5. Non-uniform temperature and species concentration measurements in a laminar flame using multi-band infrared absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Ma, Liu Hao; Lau, Lok Yin; Ren, Wei

    2017-03-01

    We report in situ measurements of non-uniform temperature, H2O and CO2 concentration distributions in a premixed methane-air laminar flame using tunable diode laser absorption spectroscopy (TDLAS). A mid-infrared, continuous-wave, room-temperature interband cascade laser (ICL) at 4183 nm was used for the sensitive detection of CO2 at high temperature.The H2O absorption lines were exploited by one distributed feedback (DFB) diode laser at 1343 nm and one ICL at 2482 nm to achieve multi-band absorption measurements with high species concentration sensitivity, high temperature sensitivity, and immunity to variations in ambient conditions. A novel profile-fitting function was proposed to characterize the non-uniform temperature and species concentrations along the line-of-sight in the flame by detecting six absorption lines of CO2 and H2O simultaneously. The flame temperature distribution was measured at different heights above the burner (5-20 mm), and compared with the thermocouple measurement with heat-transfer correction. Our TDLAS measured temperature of the central flame was in excellent agreement (<1.5% difference) with the thermocouple data.The TDLAS results were also compared with the CFD simulations using a detailed chemical kinetics mechanism (GRI 3.0) and considering the heat loss to the surroundings.The current CFD simulation overpredicted the flame temperature in the gradient region, but was in excellent agreement with the measured temperature and species concentration in the core of the flame.

  6. Experimental demonstration of terahertz metamaterial absorbers with a broad and flat high absorption band.

    PubMed

    Huang, Li; Chowdhury, Dibakar Roy; Ramani, Suchitra; Reiten, Matthew T; Luo, Sheng-Nian; Taylor, Antoinette J; Chen, Hou-Tong

    2012-01-15

    We present the design, numerical simulations and experimental measurements of terahertz metamaterial absorbers with a broad and flat absorption top over a wide incidence angle range for either transverse electric or transverse magnetic polarization depending on the incident direction. The metamaterial absorber unit cell consists of two sets of structures resonating at different but close frequencies. The overall absorption spectrum is the superposition of individual components and becomes flat at the top over a significant bandwidth. The experimental results are in excellent agreement with numerical simulations.

  7. Theoretical study on the photofragment branching ratios and anisotropy parameters of ICl in the second absorption band

    NASA Astrophysics Data System (ADS)

    Matsuoka, Takahide; Yabushita, Satoshi

    2014-01-01

    Potential energy curves, transition dipole moments, and non-adiabatic coupling terms of the excited states of ICl molecule have been obtained by the spin-orbit configuration interaction method to examine the branching ratios and the anisotropy parameters of the photodissociation process in the second absorption band. The calculation of the branching ratios with the time-dependent coupled Schrödinger equations, including the quantum interference effect between the 0+(III) and 0+(IV) states, shows good agreement with recent experiments, thus resolves the long standing disagreement. The contribution of the quantum interference effect to the photodissociation process is discussed based on a time-dependent perturbation treatment.

  8. Higher-order mode absorption measurement of X-band choke-mode cavities in a radial line structure

    NASA Astrophysics Data System (ADS)

    Zha, Hao; Shi, Jiaru; Wu, Xiaowei; Chen, Huaibi

    2016-04-01

    An experiment is presented to study the higher-order mode (HOM) suppression of X-band choke-mode structures with a vector network analyzer (VNA). Specific radial line disks were built to test the reflection from the corresponding damping load and different choke geometries. The mismatch between the radial lines and the VNA was calibrated through a special multi-short-load calibration method. The measured reflections of different choke geometries showed good agreement with the theoretical calculations and verified the HOM absorption feature of each geometric design.

  9. Analysis of functional groups in atmospheric aerosols by infrared spectroscopy: sparse methods for statistical selection of relevant absorption bands

    NASA Astrophysics Data System (ADS)

    Takahama, Satoshi; Ruggeri, Giulia; Dillner, Ann M.

    2016-07-01

    Various vibrational modes present in molecular mixtures of laboratory and atmospheric aerosols give rise to complex Fourier transform infrared (FT-IR) absorption spectra. Such spectra can be chemically informative, but they often require sophisticated algorithms for quantitative characterization of aerosol composition. Naïve statistical calibration models developed for quantification employ the full suite of wavenumbers available from a set of spectra, leading to loss of mechanistic interpretation between chemical composition and the resulting changes in absorption patterns that underpin their predictive capability. Using sparse representations of the same set of spectra, alternative calibration models can be built in which only a select group of absorption bands are used to make quantitative prediction of various aerosol properties. Such models are desirable as they allow us to relate predicted properties to their underlying molecular structure. In this work, we present an evaluation of four algorithms for achieving sparsity in FT-IR spectroscopy calibration models. Sparse calibration models exclude unnecessary wavenumbers from infrared spectra during the model building process, permitting identification and evaluation of the most relevant vibrational modes of molecules in complex aerosol mixtures required to make quantitative predictions of various measures of aerosol composition. We study two types of models: one which predicts alcohol COH, carboxylic COH, alkane CH, and carbonyl CO functional group (FG) abundances in ambient samples based on laboratory calibration standards and another which predicts thermal optical reflectance (TOR) organic carbon (OC) and elemental carbon (EC) mass in new ambient samples by direct calibration of infrared spectra to a set of ambient samples reserved for calibration. We describe the development and selection of each calibration model and evaluate the effect of sparsity on prediction performance. Finally, we ascribe

  10. Iron absorption band analysis for the discrimination of iron rich zones

    NASA Technical Reports Server (NTRS)

    Rowan, L. C. (Principal Investigator)

    1973-01-01

    The author has identified the following significant results. A lineament study of the Nevada test site is near completion. Two base maps (1:500,000) have been prepared, one of band 7 lineaments and the other of band 5 lineaments. In general, more lineaments and more faults are seen on band 5. About 45% of the lineaments appear to be faults and contacts, the others being predominantly streams, roads, railway tracks, and mountain crests. About 25% of the lineaments are unidentified so far. Special attention is being given to unmapped extensions of faults, groups of unmapped lineaments, and known mineralized areas and alteration zones. Earthquake epicenters recorded from 1869 to 1963 have been plotted on the two base maps. Preliminary examination as yet indicates no basic correlation with the lineaments. Attempts are being made to subtract bands optically, using an I2S viewer, an enlarger, and a data color viewer. Success has been limited so far due to technical difficulties, mainly vignetting and poor light sources, within the machines. Some vegetation and rock type differences, however, have been discerned.

  11. Shape of impurity electronic absorption bands in a nematic liquid crystal

    SciTech Connect

    Aver`yanov, E.M.

    1995-02-01

    It is shown that the anisotropic intermolecular impurity-matrix interactions, statistical orientation properties, and the electronic structure of the uniaxial impurity molecules considerably affect the spectral moments of the impurity electronic adsorption bands in a nematic liquid crystal. 15 refs., 3 figs.

  12. Is a pyrene-like molecular ion the cause of the 4,430-angstroms diffuse interstellar absorption band?

    NASA Technical Reports Server (NTRS)

    Salama, F.; Allamandola, L. J.

    1992-01-01

    The diffuse interstellar bands (DIBs), ubiquitous absorption features in astronomical spectra, have been known since early this century and now number more than a hundred. Ranging from 4,400 angstroms to the near infrared, they differ markedly in depth, width and shape, making the concept of a single carrier unlikely. Whether they are due to gas or grains is not settled, but recent results suggest that the DIB carriers are quite separate from the grains that cause visual extinction. Among molecular candidates the polycyclic aromatic hydrocarbons (PAHs) have been proposed as the possible carriers of some of the DIBs, and we present here laboratory measurements of the optical spectrum of the pyrene cation C16H10+ in neon and argon matrices. The strongest absorption feature falls at 4,435 +/- 5 angstroms in the argon matrix and 4,395 +/- 5 angstroms in the neon matrix, both close to the strong 4,430-angstroms DIB. If this or a related pyrene-like species is responsible for this particular band, it must account for 0.2% of all cosmic carbon. The ion also shows an intense but puzzling broad continuum, extending from the ultraviolet to the visible, similar to what is seen in the naphthalene cation and perhaps therefore a common feature of all PAH cations. This may provide an explanation of how PAHs convert a large fraction of interstellar radiation from ultraviolet and visible wavelengths down to the infrared.

  13. THE 217.5 nm BAND, INFRARED ABSORPTION, AND INFRARED EMISSION FEATURES IN HYDROGENATED AMORPHOUS CARBON NANOPARTICLES

    SciTech Connect

    Duley, W. W.; Hu, Anming E-mail: a2hu@uwaterloo.ca

    2012-12-20

    We report on the preparation of hydrogenated amorphous carbon nanoparticles whose spectral characteristics include an absorption band at 217.5 nm with the profile and characteristics of the interstellar 217.5 nm feature. Vibrational spectra of these particles also contain the features commonly observed in absorption and emission from dust in the diffuse interstellar medium. These materials are produced under ''slow'' deposition conditions by minimizing the flux of incident carbon atoms and by reducing surface mobility. The initial chemistry leads to the formation of carbon chains, together with a limited range of small aromatic ring molecules, and eventually results in carbon nanoparticles having an sp {sup 2}/sp {sup 3} ratio Almost-Equal-To 0.4. Spectroscopic analysis of particle composition indicates that naphthalene and naphthalene derivatives are important constituents of this material. We suggest that carbon nanoparticles with similar composition are responsible for the appearance of the interstellar 217.5 nm band and outline how these particles can form in situ under diffuse cloud conditions by deposition of carbon on the surface of silicate grains. Spectral data from carbon nanoparticles formed under these conditions accurately reproduce IR emission spectra from a number of Galactic sources. We provide the first detailed fits to observational spectra of Type A and B emission sources based entirely on measured spectra of a carbonaceous material that can be produced in the laboratory.

  14. Spectroscopic determination of leaf biochemistry using band-depth analysis of absorption features and stepwise multiple linear regression

    USGS Publications Warehouse

    Kokaly, R.F.; Clark, R.N.

    1999-01-01

    We develop a new method for estimating the biochemistry of plant material using spectroscopy. Normalized band depths calculated from the continuum-removed reflectance spectra of dried and ground leaves were used to estimate their concentrations of nitrogen, lignin, and cellulose. Stepwise multiple linear regression was used to select wavelengths in the broad absorption features centered at 1.73 ??m, 2.10 ??m, and 2.30 ??m that were highly correlated with the chemistry of samples from eastern U.S. forests. Band depths of absorption features at these wavelengths were found to also be highly correlated with the chemistry of four other sites. A subset of data from the eastern U.S. forest sites was used to derive linear equations that were applied to the remaining data to successfully estimate their nitrogen, lignin, and cellulose concentrations. Correlations were highest for nitrogen (R2 from 0.75 to 0.94). The consistent results indicate the possibility of establishing a single equation capable of estimating the chemical concentrations in a wide variety of species from the reflectance spectra of dried leaves. The extension of this method to remote sensing was investigated. The effects of leaf water content, sensor signal-to-noise and bandpass, atmospheric effects, and background soil exposure were examined. Leaf water was found to be the greatest challenge to extending this empirical method to the analysis of fresh whole leaves and complete vegetation canopies. The influence of leaf water on reflectance spectra must be removed to within 10%. Other effects were reduced by continuum removal and normalization of band depths. If the effects of leaf water can be compensated for, it might be possible to extend this method to remote sensing data acquired by imaging spectrometers to give estimates of nitrogen, lignin, and cellulose concentrations over large areas for use in ecosystem studies.We develop a new method for estimating the biochemistry of plant material using

  15. Presence of terrestrial atmospheric gas absorption bands in standard extraterrestrial solar irradiance curves in the near-infrared spectral region.

    PubMed

    Gao, B C; Green, R O

    1995-09-20

    The solar irradiance curves compiled by Wehrli [Physikalisch-Meteorologisches Observatorium Publ. 615 (World Radiation Center, Davosdorf, Switzerland, 1985)] and by Neckel and Labs [Sol. Phys. 90, 205 (1984)] are widely used. These curves were obtained based on measurements of solar radiation from the ground and from aircraft platforms. Contaminations in these curves by atmospheric gaseous absorptions were inevitable. A technique for deriving the transmittance spectrum of the Sun's atmosphere from high-resolution (0.01 cm(-1)) solar occultation spectra measured above the Earth's atmosphere by the use of atmospheric trace molecule spectroscopy (ATMOS) aboard the space shuttle is described. The comparisons of the derived ATMOS solar transmittance spectrum with the two solar irradiance curves show that he curve derived by Wehrli contains many absorption features in the 2.0-2.5-µm region that are not of solar origin, whereas the curve obtained by Neckel and Labs is completely devoid of weak solar absorption features that should be there. An Earth atmospheric oxygen band at 1.268 µm and a water-vapor band near 0.94 µm are likely present in the curve obtained by Wehrli. It is shown that the solar irradiance measurement errors in some narrow spectral intervals can be as large as 20%. An improved solar irradiance spectrum is formed by the incorporation of the solar transmittance spectrum derived from the ATMOS data into the solar irradiance spectrum from Neckel and Labs. The availability of a new solar spectrum from 50 to 50 000 cm(-1) from the U.S. Air Force Phillips Laboratory is also discussed.

  16. Infrared, visible and ultraviolet absorptions of transition metal doped ZnS crystals with spin-polarized bands

    SciTech Connect

    Zhang, J.H.; Ding, J.W.; Cao, J.X.; Zhang, Y.L.

    2011-03-15

    The formation energies, electronic structures and optical properties of TM:ZnS systems (TM=Cr{sup 2+}, Mn{sup 2+}, Fe{sup 2+}, Co{sup 2+} and Ni{sup 2+}) are investigated by using the first principles method. It is found that the wurtzite and zinc-blende structures have about the same stability, and thus can coexist in the TM:ZnS system. From the wurtzite TM:ZnS, especially, a partially filled intermediate band (IB) is obtained at TM=Cr{sup 2+}, Ni{sup 2+} and Fe{sup 2+}, while it is absent at TM=Mn{sup 2+} and Co{sup 2+}. The additional absorptions are obtained in infrared, visible and ultraviolet (UV) regions, due to the completely spin-polarized IB at Fermi level. The results are very helpful for both the designs and applications of TM:ZnS opto-electronics devices, such as solar-cell prototype. -- Graphical abstract: Absorption coefficients of w-TM{sub x}Zn{sub 1-x}S crystals (TM=Cr{sup 2+}, Mn{sup 2+}, Fe{sup 2+}, Co{sup 2+} and Ni{sup 2+}) at x=0.028. The results may be helpful for the design and applications of TM:ZnS devices, especially for the new high efficiency solar-cell prototype, UV detector and UV LEDs. Display Omitted Research highlights: > It is found that the wurtzite and zinc-blende structures can coexist in TM:ZnS. > An intermediate band is obtained in TM:ZnS at TM=Cr{sup 2+}, Ni{sup 2+} and Fe{sup 2+}. > The absorption coefficients are obtained in infrared, visible and ultraviolet regions.

  17. On the sub-band gap optical absorption in heat treated cadmium sulphide thin film deposited on glass by chemical bath deposition technique

    SciTech Connect

    Chattopadhyay, P.; Karim, B.; Guha Roy, S.

    2013-12-28

    The sub-band gap optical absorption in chemical bath deposited cadmium sulphide thin films annealed at different temperatures has been critically analyzed with special reference to Urbach relation. It has been found that the absorption co-efficient of the material in the sub-band gap region is nearly constant up to a certain critical value of the photon energy. However, as the photon energy exceeds the critical value, the absorption coefficient increases exponentially indicating the dominance of Urbach rule. The absorption coefficients in the constant absorption region and the Urbach region have been found to be sensitive to annealing temperature. A critical examination of the temperature dependence of the absorption coefficient indicates two different kinds of optical transitions to be operative in the sub-band gap region. After a careful analyses of SEM images, energy dispersive x-ray spectra, and the dc current-voltage characteristics, we conclude that the absorption spectra in the sub-band gap domain is possibly associated with optical transition processes involving deep levels and the grain boundary states of the material.

  18. Broad Band Light Absorption and High Photocurrent of (In,Ga)N Nanowire Photoanodes Resulting from a Radial Stark Effect.

    PubMed

    Kamimura, Jumpei; Bogdanoff, Peter; Corfdir, Pierre; Brandt, Oliver; Riechert, Henning; Geelhaar, Lutz

    2016-12-21

    The photoelectrochemical properties of (In,Ga)N nanowire photoanodes are investigated using H2O2 as a hole scavenger to prevent photocorrosion. Under simulated solar illumination, In0.16Ga0.84N nanowires grown by plasma-assisted molecular beam epitaxy show a high photocurrent of 2.7 mA/cm(2) at 1.2 V vs reversible hydrogen electrode. This value is almost the theoretical maximum expected from the corresponding band gap (2.8 eV) for homogeneous bulk material without taking into account surface effects. These nanowires exhibit a higher incident photon-to-current conversion efficiency over a broader wavelength range and a higher photocurrent than a compact layer with higher In content of 28%. These results are explained by the combination of built-in electric fields at the nanowire sidewall surfaces and compositional fluctuations in (In,Ga)N, which gives rise to a radial Stark effect. This effect enables spatially indirect transitions at energies much lower than the band gap. The resulting broad band light absorption leads to high photocurrents. This benefit of the radial Stark effect in (In,Ga)N nanowires for solar harvesting applications opens up the perspective to break the theoretical limit for photocurrents.

  19. Fluorinated graphene oxide for enhanced S and X-band microwave absorption

    SciTech Connect

    Sudeep, P. M.; Vinayasree, S.; Mohanan, P.; Ajayan, P. M.; Narayanan, T. N.; Anantharaman, M. R.

    2015-06-01

    Here we report the microwave absorbing properties of three graphene derivatives, namely, graphene oxide (GO), fluorinated GO (FGO, containing 5.6 at. % Fluorine (F)), and highly FGO (HFGO, containing 23 at. % F). FGO is known to be exhibiting improved electrochemical and electronic properties when compared to GO. Fluorination modifies the dielectric properties of GO and hence thought of as a good microwave absorber. The dielectric permittivities of GO, FGO, and HFGO were estimated in the S (2 GHz to 4 GHz) and X (8 GHz to 12 GHz) bands by employing cavity perturbation technique. For this, suspensions containing GO/FGO/HFGO were made in N-Methyl Pyrrolidone (NMP) and were subjected to cavity perturbation. The reflection loss was then estimated and it was found that −37 dB (at 3.2 GHz with 6.5 mm thickness) and −31 dB (at 2.8 GHz with 6 mm thickness) in the S band and a reflection loss of −18 dB (at 8.4 GHz with 2.5 mm thickness) and −10 dB (at 11 GHz with 2 mm thickness) in the X band were achieved for 0.01 wt. % of FGO and HFGO in NMP, respectively, suggesting that these materials can serve as efficient microwave absorbers even at low concentrations.

  20. VUV Fourier-transform absorption study of the Lyman and Werner bands in D2.

    PubMed

    de Lange, Arno; Dickenson, Gareth D; Salumbides, Edcel J; Ubachs, Wim; de Oliveira, Nelson; Joyeux, Denis; Nahon, Laurent

    2012-06-21

    An extensive survey of the D(2) absorption spectrum has been performed with the high-resolution VUV Fourier-transform spectrometer employing synchrotron radiation. The frequency range of 90,000-119,000 cm(-1) covers the full depth of the potential wells of the B (1)Σ(u)(+), B' (1)Σ(u)(+), and C (1)Π(u) electronic states up to the D(1s) + D(2l) dissociation limit. Improved level energies of rovibrational levels have been determined up to respectively v = 51, v = 13, and v = 20. Highest resolution is achieved by probing absorption in a molecular gas jet with slit geometry, as well as in a liquid helium cooled static gas cell, resulting in line widths of ≈0.35 cm(-1). Extended calibration methods are employed to extract line positions of D(2) lines at absolute accuracies of 0.03 cm(-1). The D (1)Π(u) and B'' (1)Σ(u)(+) electronic states correlate with the D(1s) + D(3l]) dissociation limit, but support a few vibrational levels below the second dissociation limit, respectively, v = 0-3 and v = 0-1, and are also included in the presented study. The complete set of resulting level energies is the most comprehensive and accurate data set for D(2). The observations are compared with previous studies, both experimental and theoretical.

  1. Multilayer Cloud Detection with the MODIS Near-Infrared Water Vapor Absorption Band

    NASA Technical Reports Server (NTRS)

    Wind, Galina; Platnick, Steven; King, Michael D.; Hubanks, Paul A,; Pavolonis, Michael J.; Heidinger, Andrew K.; Yang, Ping; Baum, Bryan A.

    2009-01-01

    Data Collection 5 processing for the Moderate Resolution Imaging Spectroradiometer (MODIS) onboard the NASA Earth Observing System EOS Terra and Aqua spacecraft includes an algorithm for detecting multilayered clouds in daytime. The main objective of this algorithm is to detect multilayered cloud scenes, specifically optically thin ice cloud overlying a lower-level water cloud, that presents difficulties for retrieving cloud effective radius using single layer plane-parallel cloud models. The algorithm uses the MODIS 0.94 micron water vapor band along with CO2 bands to obtain two above-cloud precipitable water retrievals, the difference of which, in conjunction with additional tests, provides a map of where multilayered clouds might potentially exist. The presence of a multilayered cloud results in a large difference in retrievals of above-cloud properties between the CO2 and the 0.94 micron methods. In this paper the MODIS multilayered cloud algorithm is described, results of using the algorithm over example scenes are shown, and global statistics for multilayered clouds as observed by MODIS are discussed. A theoretical study of the algorithm behavior for simulated multilayered clouds is also given. Results are compared to two other comparable passive imager methods. A set of standard cloudy atmospheric profiles developed during the course of this investigation is also presented. The results lead to the conclusion that the MODIS multilayer cloud detection algorithm has some skill in identifying multilayered clouds with different thermodynamic phases

  2. Would the solvent effect be the main cause of band shift in the theoretical absorption spectrum of large lanthanide complexes?

    NASA Astrophysics Data System (ADS)

    Freire, Ricardo O.; Rodrigues, Nailton M.; Rocha, Gerd B.; Gimenez, Iara F.; da Costa Junior, Nivan B.

    2011-06-01

    As most reactions take place in solution, the study of solvent effects on relevant molecular properties - either by experimental or theoretical methods - is crucial for the design of new processes and prediction of technological properties. In spite of this, only few works focusing the influence of the solvent nature specifically on the spectroscopic properties of lanthanide complexes can be found in the literature. The present work describes a theoretical study of the solvent effect on the prediction of the absorption spectra for lanthanide complexes, but other possible relevant factors have been also considered such as the molecular geometry and the excitation window used for interaction configuration (CI) calculations. The [Eu(ETA) 2· nH 2O] +1 complex has been chosen as an ideal candidate for this type of study due to its small number of atoms (only 49) and also because the absorption spectrum exhibits a single band. Two Monte Carlo simulations were performed, the first one considering the [Eu(ETA) 2] +1 complex in 400 water molecules, evidencing that the complex presents four coordinated water molecules. The second simulation considered the [Eu(ETA) 2·4H 2O] +1 complex in 400 ethanol molecules, in order to evaluate the solvent effect on the shift of the maximum absorption in calculated spectra, compared to the experimental one. Quantum chemical studies were also performed in order to evaluate the effect of the accuracy of calculated ground state geometry on the prediction of absorption spectra. The influence of the excitation window used for CI calculations on the spectral shift was also evaluated. No significant solvent effect was found on the prediction of the absorption spectrum for [Eu(ETA) 2·4H 2O] +1 complex. A small but significant effect of the ground state geometry on the transition energy and oscillator strength was also observed. Finally it must be emphasized that the absorption spectra of lanthanide complexes can be predicted with great accuracy

  3. On the Use of Difference Bands for Modeling SF_6 Absorption in the 10μm Atmospheric Window

    NASA Astrophysics Data System (ADS)

    Faye, Mbaye; Manceron, Laurent; Roy, P.; Boudon, Vincent; Loete, Michel

    2016-06-01

    To model correctly the SF_6 atmospheric absorption requires the knowledge of the spectroscopic parameters of all states involved in the numerous hot bands in the 10,5μm atmospheric transparency window. However, due to their overlapping, a direct analysis of the hot bands near the 10,5μm absorption of SF_6 in the atmospheric window is not possible. It is necessary to use another strategy, gathering information in the far and mid infrared regions on initial and final states to compute the relevant total absorption. In this talk, we present new results from the analysis of spectra recorded at the AILES beamline at the SOLEIL Synchrotron facility. For these measurements, we used a IFS125HR interferometer combined with the synchrotron radiation in the 100-3200 wn range, coupled to a cryogenic multiple pass cell. The optical path length was varied from 45 to 141m with measuring temperatures between 223 and 153+/-5 K. The new information obtained on νb{2}+νb{4}-νb{5}, 2νb{5}-νb{6} and νb{3}+νb{6}-νb{4} allowed to derive improved parameters for νb{5}, 2νb{5} and νb{3}+νb{6}. In turn, they are used to model the more important νb{3}+νb{5}-νb{5} and νb{3}+νb{6}-νb{6} hot band contributions. By including these new parameters in the XTDS model, we substantially improved the SF_6 parameters used to model the atmosphere. F. Kwabia Tchana, F. Willaert, X. Landsheere, J. M. Flaud, L. Lago, M. Chapuis, P. Roy, L. Manceron. A new, low temperature long-pass cell for mid-IR to THz Spectroscopy and Synchrotron Radiation Use. Rev. Sci. Inst. 84, 093101, (2013) C. Wenger, V. Boudon, M. Rotger, M. Sanzharov, and J.-P. Champion,"XTDS and SPVIEW: Graphical tools for Analysis and Simulation of High Resolution Molecular Spectra", J. Mol. Spectrosc. 251, 102 (2008)

  4. A thermal broadening analysis of absorption spectra of the D1/D2/cytochrome b-559 complex in terms of Gaussian decomposition sub-bands.

    PubMed

    Cattaneo, R; Zucchelli, G; Garlaschi, F M; Finzi, L; Jennings, R C

    1995-11-21

    Absorption spectra of the isolated D1/D2/cytochrome b-559 complex have been measured in the temperature range 80-300 K. All spectra were analyzed in terms of a linear combination of Gaussian bands and the thermal broadening data interpreted in terms of a model in which the spectrum of each pigment site is broadened by (a) a homogeneous component due to linear electron-phonon coupling to a low-frequency protein vibration and (b) an inhomogeneous component associated with stochastic fluctuations at each pigment site. In order to obtain a numerically adequate description of the absorption spectra, a minimum number of five sub-bands is required. Further refinement of this sub-band description was achieved by taking into account published data from hole burning and absorption difference spectroscopy. In this way, both a six sub-band description and a seven sub-band description were generated. In arriving at the seven sub-band description, the original five sub-band wavelength positions were essentially unchanged. Thermal broadening analysis of the seven sub-band description yielded data which displayed the closest correspondence with the literature observations. The wavelength positions of the sub-bands were near 661, 667, 670, and 675 nm, with two bands near 680 and 684 nm. The two almost isoenergetic sub-bands near 680 nm, identified as P680 and pheophytin, have optical reorganization energies around 40 and 16 cm-1, respectively. All other sub-bands, identified as accessory pigments, have optical reorganization energies close to 16 cm-1.(ABSTRACT TRUNCATED AT 250 WORDS)

  5. Europa's ultraviolet absorption band (260 to 320 nm) - Temporal and spatial evidence from IUE

    NASA Technical Reports Server (NTRS)

    Ockert, Maureen E.; Nelson, Robert M.; Lane, Arthur L.; Matson, Dennis L.

    1987-01-01

    An analysis of 33 IUE UV spectra of Europa, obtained from 1978 to 1982 for orbital phase angles of 21 to 343 deg, confirms that the Lane et al. (1981) absorption feature, centered at 280 nm, is most clearly revealed when 223-333 deg orbital phase angle spectra are ratioed to those nearest 90 deg. The feature's strength is noted to have persisted over the 5-year period studied, suggesting that no large endogenically or exogenically generated changes in surface sulfur dioxide concentration have occurred. These results further substantiate the Lane et al. hypothesis that the feature is due to the implantation of Io plasma torus-derived sulfur ions on the Europa trailing side's water-ice surface.

  6. Optimizing organic photovoltaics using tailored heterojunctions: A photoinduced absorption study of oligothiophenes with low band gaps

    NASA Astrophysics Data System (ADS)

    Schueppel, R.; Schmidt, K.; Uhrich, C.; Schulze, K.; Wynands, D.; Brédas, J. L.; Brier, E.; Reinold, E.; Bu, H.-B.; Baeuerle, P.; Maennig, B.; Pfeiffer, M.; Leo, K.

    2008-02-01

    A power conversion efficiency of 3.4% with an open-circuit voltage of 1V was recently demonstrated in a thin film solar cell utilizing fullerene C60 as acceptor and a new acceptor-substituted oligothiophene with an optical gap of 1.77eV as donor [K. Schulze , Adv. Mater. (Weinheim, Ger.) 18, 2872 (2006)]. This prompted us to systematically study the energy- and electron transfer processes at the oligothiophene:fullerene heterojunction for a homologous series of these oligothiophenes. Cyclic voltammetry and ultraviolet photoelectron spectroscopy data show that the heterojunction is modified due to tuning of the highest occupied molecular orbital energy for different oligothiophene chain lengths, while the lowest unoccupied molecular orbital energy remains essentially fixed due to the presence of electron-withdrawing end groups (dicyanovinyl) attached to the oligothiophene. Use of photoinduced absorption (PA) allows the study of the electron transfer process at the heterojunction to C60 . Quantum-chemical calculations performed at the density functional theory and/or time-dependent density functional theory level and cation absorption spectra of diluted DCVnT provide an unambiguous identification of the transitions observed in the PA spectra. Upon increasing the effective energy gap of the donor-acceptor pair by increasing the ionization energy of the donor, photoinduced electron transfer is eventually replaced with energy transfer, which alters the photovoltaic operation conditions. The optimum open-circuit voltage of a solar cell is thus a trade-off between efficient charge separation at the interface and maximized effective gap. It appears that the open-circuit voltages of 1.0-1.1V in our solar cell devices have reached an optimum since higher voltages result in a loss in charge separation efficiency.

  7. Energy conversion within infrared plasmonic absorption metamaterials for multi-band resonance

    NASA Astrophysics Data System (ADS)

    Li, Yongqian; Su, Lei; Xu, Xiaolun; Zhang, Chenglin; Wang, Binbin

    2015-05-01

    The energy conversion within the cross-shaped plasmonic absorber metamaterials (PAM) was investigated theoretically and numerically in the infrared range based on the Poynting's theorem of electromagnetic energy. From the microscopic details, the heat generation owing to the electric current accounts for the majority of the energy conversion, while the magnetic resonance plays a negligible role. The PAMs possess three distinct resonant peaks standing independently, which are attributed to the polarization sensitive excitation of plasmonic resonance. Field redistribution and enhancement associated with multiplex resonant electromagnetic wave passing through the PAM medium provided insight into the energy conversion processes inside the nanostructure. The research results will assist the design of novel plasmon enhanced infrared detectors with multiple-band detection.

  8. Thermodynamic consequence of the new attribution of bands in the electronic absorption spectrum of electron donor-iodine-solvent systems

    NASA Astrophysics Data System (ADS)

    Abramov, Sergey P.

    1999-06-01

    The subject review pays attention to the peculiarities in behaviour of bands in the electronic absorption spectra of electron donor-iodine-solvent systems, the appearance of which is associated with the intermolecular interaction of molecular iodine with electron donor organic molecules. The new concept of the bands’ attribution to the isomeric equilibrium molecular charge-transfer complexes (CTCs) of CTC-I and CTC-II types is considered. The features of possible phase transitions in the solid state are discussed on the basis of the thermodynamic properties and electronic structures of the CTC-I and CTC-II in electron donor-iodine-solvent systems. The stabilisation of the CTC-II structure with the temperature lowering coincided in many cases with the electrons’ localisation in the solid state structures having charge-transfer bonds.

  9. Depolarisation of light scattered by disperse systems of low-dimensional potassium polytitanate nanoparticles in the fundamental absorption band

    SciTech Connect

    Zimnyakov, D A; Yuvchenko, S A; Pravdin, A B; Kochubey, V I; Gorokhovsky, A V; Tretyachenko, E V; Kunitsky, A I

    2014-07-31

    The results of experimental studies of depolarising properties of disperse systems on the basis of potassium polytitanate nanoplatelets and nanoribbons in the visible and near-UV spectral regions are presented. It is shown that in the fundamental absorption band of the nanoparticle material the increase in the depolarisation factor takes place for the radiation scattered perpendicularly to the direction of the probing beam. For nanoribbons a pronounced peak of depolarisation is observed, which is caused by the essential anisotropy of the particles shape and the peculiarities of the behaviour of the material dielectric function. The empirical data are compared with the theoretical results for 'nanodiscs' and 'nanoneedles' with the model dielectric function, corresponding to that obtained from optical constants of the titanium dioxide dielectric function. (laser biophotonics)

  10. Is a pyrene-like molecular ion the cause of the 4,430-A diffuse interstellar absorption band?

    NASA Technical Reports Server (NTRS)

    Salama, F.; Allamandola, L. J.

    1992-01-01

    The diffuse interstellar band (DIB) absorption features of astronomical spectra are suggested by recent results to be separable from the grains that cause visual extinction. Attention is presently given to laboratory measurements of the optical spectrum of the pyrene cation C16H10(+), which is one of the polycyclic aromatic hydrocarbon (PAH) molecular candidates proposed as carriers for DIBs. This ion exhibits an intense but strangely broad continuum similar to that of the naphthalene cation, so that this may be a common feature of all PAH cations and the basis of an explanation for PAHs' converting of an interstellar radiation fraction as large as that from the UV and visible range down to the IR.

  11. Comparison of line-by-line and band models of near-IR methane absorption applied to outer planet atmospheres

    NASA Astrophysics Data System (ADS)

    Sromovsky, L. A.; Fry, P. M.; Boudon, V.; Campargue, A.; Nikitin, A.

    2012-03-01

    Recent improvements in high spectral resolution measurements of methane absorption at wavenumbers between 4800 cm-1 and 7919 cm-1 have greatly increased the number of lines with known lower state energies, the number of weak lines, and the number of lines observed at low temperatures (Campargue, A., Wang, L., Kassi, S., Mašát, M., Votava, O. [2010]. J. Quant. Spectrosc. Radiat. Trans. 111, 1141-1151; Campargue, A., Wang, L., Liu, A.W., Hu, S.M., Kassi, S. [2010]. Chem. Phys. 373, 203-210; Mondelain, D., Kassi, S., Wang, L.C. [2011]. Phys. Chem. Chem. Phys. 13, 7985-7996; Nikitin, A.V. et al. [2011a]. J. Mol. Spectrosc. 268, 93-106; Nikitin, A.V. et al. [2010]. J. Quant. Spectrosc. Radiat. Trans. 111, 2211-2224; Wang, L., Kassi, S., Campargue, A. [2010]. J. Quant. Spectrosc. Radiat. Trans. 111, 1130-1140; Wang, L., Kassi, S., Liu, A.W., Hu, S.M., Campargue, A. [2011]. J. Quant. Spectrosc. Radiat. Trans. 112, 937-951), making it possible to fit near-IR spectra of Titan using line-by-line calculations instead of band models (Bailey, J., Ahlsved, L., Meadows, V.S. [2011]. Icarus 213, 218-232; de Bergh, C. et al. [2011]. Planet. Space Sci. doi:10.1016/j.pss.2011.05.003). Using these new results, we compiled an improved line list relative that used by Bailey et al. by updating several spectral regions with either calculated or more recently measured line parameters, revising lower state energy estimates for lines lacking them, and adding room temperature lines to make the list applicable over a wider range of temperatures. We compared current band models with line-by-line calculations using this new line list, both to assess the behavior of band models, and to identify remaining issues with line-by-line calculations when applied to outer planet atmospheres and over a wider range of wavelengths. Comparisons were made for a selection of uniform paths representing outer planet conditions and for representative non-uniform paths within the atmospheres of Uranus, Saturn

  12. Incoherent broad-band cavity-enhanced absorption spectroscopy of the marine boundary layer species I2, IO and OIO.

    PubMed

    Vaughan, Stewart; Gherman, Titus; Ruth, Albert A; Orphal, Johannes

    2008-08-14

    The novel combination of incoherent broad-band cavity-enhanced absorption spectroscopy (IBBCEAS) and a discharge-flow tube for the study of three key atmospheric trace species, I(2), IO and OIO, is reported. Absorption measurements of I(2) and OIO at lambda=525-555 nm and IO at lambda=420-460 nm were made using a compact cavity-enhanced spectrometer employing a 150 W short-arc Xenon lamp. The use of a flow system allowed the monitoring of the chemically short-lived radical species IO and OIO to be conducted over timescales of several seconds. We report detection limits of approximately 26 pmol mol(-1) for I(2) (L=81 cm, acquisition time 60 s), approximately 45 pmol mol(-1) for OIO (L=42.5 cm, acquisition time 5 s) and approximately 210 pmol mol(-1) for IO (L=70 cm, acquisition time 60 s), demonstrating the usefulness of this approach for monitoring these important species in both laboratory studies and field campaigns.

  13. Anomalous band gap behavior in mixed Sn and Pb perovskites enables broadening of absorption spectrum in solar cells.

    PubMed

    Hao, Feng; Stoumpos, Constantinos C; Chang, Robert P H; Kanatzidis, Mercouri G

    2014-06-04

    Perovskite-based solar cells have recently been catapulted to the cutting edge of thin-film photovoltaic research and development because of their promise for high-power conversion efficiencies and ease of fabrication. Two types of generic perovskites compounds have been used in cell fabrication: either Pb- or Sn-based. Here, we describe the performance of perovskite solar cells based on alloyed perovskite solid solutions of methylammonium tin iodide and its lead analogue (CH3NH3Sn(1-x)Pb(x)I3). We exploit the fact that, the energy band gaps of the mixed Pb/Sn compounds do not follow a linear trend (the Vegard's law) in between these two extremes of 1.55 and 1.35 eV, respectively, but have narrower bandgap (<1.3 eV), thus extending the light absorption into the near-infrared (~1,050 nm). A series of solution-processed solid-state photovoltaic devices using a mixture of organic spiro-OMeTAD/lithium bis(trifluoromethylsulfonyl)imide/pyridinium additives as hole transport layer were fabricated and studied as a function of Sn to Pb ratio. Our results show that CH3NH3Sn(0.5)Pb(0.5)I3 has the broadest light absorption and highest short-circuit photocurrent density ~20 mA cm(-2) (obtained under simulated full sunlight of 100 mW cm(-2)).

  14. The first UV absorption band for indole is not due to two simultaneous orthogonal electronic transitions differing in dipole moment.

    PubMed

    Catalán, Javier

    2015-05-21

    The currently accepted model for the photophysics of indole assumes that the first UV absorption band encompasses two orthogonal electronic transitions ((1)Lb and (1)La), leading to two electronic states with a markedly different dipole moment. However, there is a body of evidence not explained by this model, which led us to develop a new photophysical model for indole. Based on the new model, the polarity of the electronic ground state (S0) in indoles is very similar to that of the first electronic excited state (S1) producing this structured emission; however, this excited state can lead to a highly dipolar excited state (S1') with largely structureless emission under the influence of the polarity of the medium, and also, very likely, of its viscosity. The molecular structure of the new excited state can be reversibly converted into the normal structure of the compound. Previous observations were confirmed by the absorption, emission, and excitation spectra for indole, as well as by its polarized emission and excitation spectra in various media. Thus, the polarized emission spectra for indole in glycerol at 283 K and 223 K showed the transition dipole moments for the emission from the first two excited states in a polar medium, S1 and S1', to differ by less than 20°.

  15. Venus within ESA probe reach

    NASA Astrophysics Data System (ADS)

    2006-03-01

    Venus Express mission controllers at the ESA Space Operations Centre (ESOC) in Darmstadt, Germany are making intensive preparations for orbit insertion. This comprises a series of telecommands, engine burns and manoeuvres designed to slow the spacecraft down from a velocity of 29000 km per hour relative to Venus, just before the first burn, to an entry velocity some 15% slower, allowing the probe to be captured into orbit around the planet. The spacecraft will have to ignite its main engine for 50 minutes in order to achieve deceleration and place itself into a highly elliptical orbit around the planet. Most of its 570 kg of onboard propellant will be used for this manoeuvre. The spacecraft’s solar arrays will be positioned so as to reduce the possibility of excessive mechanical load during engine ignition. Over the subsequent days, a series of additional burns will be done to lower the orbit apocentre and to control the pericentre. The aim is to end up in a 24-hour orbit around Venus early in May. The Venus orbit injection operations can be followed live at ESA establishments, with ESOC acting as focal point of interest (see attached programme). In all establishments, ESA specialists will be on hand for interviews. ESA TV will cover this event live from ESOC in Darmstadt. The live transmission will be carried free-to-air. For broadcasters, complete details of the various satellite feeds are listed at http://television.esa.int. The event will be covered on the web at venus.esa.int. The website will feature regular updates, including video coverage of the press conference and podcast from the control room at ESA’s Operations Centre. Media representatives wishing to follow the event at one of the ESA establishments listed below are requested to fill in the attached registration form and fax it back to the place of their choice. For further information, please contact: ESA Media Relations Division Tel : +33(0)1.53.69.7155 Fax: +33(0)1.53.69.7690 Venus Express

  16. The Fundamental Quadrupole Band of (14)N2: Line Positions from High-Resolution Stratospheric Solar Absorption Spectra

    NASA Technical Reports Server (NTRS)

    Rinsland, C. P.; Zander, R.; Goldman, A.; Murcray, F. J.; Murcray, D. G.; Grunson, M. R.; Farmer, C. B.

    1991-01-01

    The purpose of this note is to report accurate measurements of the positions of O- and S-branch lines of the (1-0) vibration-rotation quadrupole band of molecular nitrogen ((14)N2) and improved Dunham coefficients derived from a simultaneous least-squares analysis of these measurements and selected infrared and far infrared data taken from the literature. The new measurements have been derived from stratospheric solar occultation spectra recorded with Fourier transform spectrometer (FTS) instruments operated at unapodized spectral resolutions of 0.002 and 0.01 /cm. The motivation for the present investigation is the need for improved N2 line parameters for use in IR atmospheric remote sensing investigations. The S branch of the N2 (1-0) quadrupole band is ideal for calibrating the line-of-sight airmasses of atmospheric spectra since the strongest lines are well placed in an atmospheric window, their absorption is relatively insensitive to temperature and is moderately strong (typical line center depths of 10 to 50% in high-resolution ground-based solar spectra and in lower stratospheric solar occultation spectra), and the volume mixing ratio of nitrogen is constant in the atmosphere and well known. However, a recent investigation has'shown the need to improve the accuracies of the N2 fine positions, intensities, air-broadened half-widths, and their temperature dependences to fully exploit this calibration capability (1). The present investigation addresses the problem of improving the accuracy of the N2 line positions.

  17. Visible-band (390-940nm) monitoring of the Pluto absorption spectrum during the New Horizons encounter

    NASA Astrophysics Data System (ADS)

    Smith, Robert J.; Marchant, Jonathan M.

    2015-11-01

    Whilst Earth-based observations obviously cannot compete with New Horizons’ on-board instrumentation in most regards, the New Horizons data set is essentially a snapshot of Pluto in July 2015. The New Horizons project team therefore coordinated a broad international observing campaign to provide temporal context and to take advantage of the once-in-a-lifetime opportunity to directly link our Earth-based view of Pluto with “ground truth” provided by in situ measurements. This both adds value to existing archival data sets and forms the basis of long term, monitoring as we watch Pluto recede from the Sun over the coming years. We present visible-band (390-940nm) monitoring of the Pluto absorption spectrum over the period July - October 2015 from the Liverpool Telescope (LT). In particular we wished to understand the well-known 6-day fluctuation in the methane ice absorption spectrum which is observable from Earth in relation to the never-before-available high resolution maps of the Pluto surface. The LT is a fully robotic 2.0m optical telescope that automatically and dynamically schedules observations across 30+ observing programmes with a broad instrument suite. It is ideal for both reactive response to dynamic events (such as the fly-by) and long term, stable monitoring with timing constraints individually optimised to the science requirements of each programme. For example past studies of the observed CH4 absorption variability have yielded ambiguity of whether they were caused by real physical changes or geometric observation constraints, in large part because of the uneven time sampling imposed by traditional telescope scheduling.

  18. 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

  19. Study of band inversion in the PbxSn1-xTe class of topological crystalline insulators using x-ray absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Mitrofanov, K. V.; Kolobov, A. V.; Fons, P.; Krbal, M.; Tominaga, J.; Uruga, T.

    2014-11-01

    PbxSn1-xTe and PbxSn1-xSe crystals belong to the class of topological crystalline insulators where topological protection is achieved due to crystal symmetry rather than time-reversal symmetry. In this work, we make use of selection rules in the x-ray absorption process to experimentally detect band inversion along the PbTe(Se)-SnTe(Se) tie-lines. The observed significant change in the ratio of intensities of L1 and L3 transitions along the tie-line demonstrates that x-ray absorption can be a useful tool to study band inversion in topological insulators.

  20. Three-pulse femtosecond spectroscopy of PbSe nanocrystals: 1S bleach nonlinearity and sub-band-edge excited-state absorption assignment.

    PubMed

    Gdor, Itay; Shapiro, Arthur; Yang, Chunfan; Yanover, Diana; Lifshitz, Efrat; Ruhman, Sanford

    2015-02-24

    Above band-edge photoexcitation of PbSe nanocrystals induces strong below band gap absorption as well as a multiphased buildup of bleaching in the 1Se1Sh transition. The amplitudes and kinetics of these features deviate from expectations based on biexciton shifts and state filling, which are the mechanisms usually evoked to explain them. To clarify these discrepancies, the same transitions are investigated here by double-pump-probe spectroscopy. Re-exciting in the below band gap induced absorption characteristic of hot excitons is shown to produce additional excitons with high probability. In addition, pump-probe experiments on a sample saturated with single relaxed excitons prove that the resulting 1Se1Sh bleach is not linear with the number of excitons per nanocrystal. This finding holds for two samples differing significantly in size, demonstrating its generality. Analysis of the results suggests that below band edge induced absorption in hot exciton states is due to excited-state absorption and not to shifted absorption of cold carriers and that 1Se1Sh bleach signals are not an accurate counter of sample excitons when their distribution includes multiexciton states.

  1. Future ESA missions in biology.

    PubMed

    Bonting, S L

    1984-01-01

    A survey is given of the life sciences research program sponsored by the European Space Agency (ESA). This program rests on a number of facilities originated by ESA: Spacelab, Space sled, Biorack, Anthrorack, Eureca and its Botany - and Protein Crystallization facilities. They are all to be brought into space and returned by one of the NASA Space Shuttles. With these facilities a wide range of space biology research will be covered: cell biology, developmental biology, botany, human physiology, radiobiology, exobiology and biotechnology. Information is given on how to prepare, submit and execute an experiment proposal.

  2. Future ESA Missions in Biology

    NASA Astrophysics Data System (ADS)

    Bonting, Sjoerd L.

    1984-12-01

    A survey is given of the life sciences research program sponsored by the European Space Agency (ESA). This program rests on a number of facilities originated by ESA: Spacelab, Space sled, Biorack, Anthrorack, Eureca and its Botany — and Protein Crystallization facilities. They are all to be brough into space and returned by one of the NASA Space Shuttles. With these facilities a wide range of space biology research will be covered: cell biology, developmental biology, botany, human physiology, radio-biology, exobiology and biotechnology. Information is given on how to prepare, submit and execute an experiment proposal.

  3. Improved Experimental Line Positions for the (1,1) Band of the b 1Σ+ - X 3Σ- Transition of O2 by Intracavity Laser Absorption Spectroscopy

    NASA Astrophysics Data System (ADS)

    O'Brien, Leah C.; O'Brien, Emily C.; O'Brien, James J.

    2012-06-01

    We report improved experimental line positions for the (1,1) band of the b 1Σ+ - X 3Σ- transition of O2. Results are comparised with previous experimental measurements and predicted values. Additionally, a new method of producing vibrationally hot molecules for use in absorption spectroscopy of stable gas phase molecules is described.

  4. Collision-Induced Absorption by H2 Pairs in the Second Overtone Band at 298 and 77.5 K: Comparison between Experimental and Theoretical Results

    NASA Technical Reports Server (NTRS)

    Brodbeck, C.; Bouanich, J.-P.; van-Thanh, Nguyen; Fu, Y.; Borysow, A.

    1999-01-01

    The collision-induced spectra of hydrogen in the region of the second overtone at 0.8 microns have been recorded at temperatures of 298 and 77.5 K and for gas densities ranging from 100 to 800 amagats. The spectral profile defined by the absorption coefficient per squared density varies significantly with the density, so that the binary absorption coefficient has been determined by extrapolations to zero density of the measured profiles. Our extrapolated measurements and our recent ab initio quantum calculation are in relatively good agreement with one another. Taking into account the very weak absorption of the second overtone band, the agreement is, however, not as good as it has become (our) standard for strong bands.

  5. Microwave-assisted synthesis of graphene-Ni composites with enhanced microwave absorption properties in Ku-band

    NASA Astrophysics Data System (ADS)

    Zhu, Zetao; Sun, Xin; Li, Guoxian; Xue, Hairong; Guo, Hu; Fan, Xiaoli; Pan, Xuchen; He, Jianping

    2015-03-01

    Recently, graphene has been applied as a new microwave absorber because of its high dielectric loss and low density. Nevertheless, the high dielectric constant of pristine graphene has caused unbalanced electromagnetic parameters and results in a bad impedance matching characteristic. In this study, we report a facile microwave-assisted heating approach to produce reduced graphene oxide-nickel (RGO-Ni) composites. The phase and morphology of as-synthesized RGO-Ni composites are characterized by XRD, Raman, FESEM and TEM. The results show that Ni nanoparticles with a diameter around 20 nm are grown densely and uniformly on the RGO sheets. In addition, enhanced microwave absorption properties in Ku-band of RGO-Ni composites is mainly due to the synergistic effect of dielectric loss and magnetic loss and the dramatically electron polarizations caused by the formation of large conductive network. The minimum reflection loss of RGO-Ni-2 composite with the thickness of 2 mm can reaches -42 dB at 17.6 GHz. The RGO-Ni composite is an attractive candidate for the new type of high performance microwave absorbing material.

  6. High resolution absorption cross sections in the transmission window region of the Schumann-Runge bands and Herzberg continuum of O2

    NASA Technical Reports Server (NTRS)

    Yoshino, K.; Esmond, J. R.; Cheung, A. S.-C.; Freeman, D. E.; Parkinson, W. H.

    1992-01-01

    Results are presented on measurements, conducted in the wavelength region 180-195 nm, and at different pressures of oxygen (between 2.5-760 torr) in order to separate the pressure-dependent absorption from the main cross sections, of the absorption cross sections of the Schumann-Runge bands in the window region between the rotational lines of S-R bands of O2. The present cross sections supersede the earlier published cross sections (Yoshino et al., 1983). The combined cross sections are presented graphically; they are available at wavenumber intervals of about 0.1/cm from the National Space Science Data Center. The Herzberg continuum cross sections are derived after subtracting calculated contributions from the Schumann-Runge bands. These are significantly smaller than any previous measurements.

  7. Effect of thickness on microwave absorptive behavior of La-Na doped Co-Zr barium hexaferrites in 18.0-26.5 GHz band

    NASA Astrophysics Data System (ADS)

    Arora, Amit; Narang, Sukhleen Bindra; Pubby, Kunal

    2017-02-01

    In this research, the microwave properties of Lanthanum-Sodium doped Cobalt-Zirconium barium hexaferrites, intended as microwave absorbers, are analyzed on Vector Network Analyzer in K-band. The results indicate that the doping has resulted in lowering of real permittivity and enhancement of dielectric losses. Real permeability has shown increase while magnetic losses have shown decrease in value with doping. All these four properties have shown very small variation with frequency in the scanned frequency range which indicates the relaxation type of behavior. Microwave absorption characteristics of these compositions are analyzed with change in sample thickness. The results demonstrate that the matching frequency of the microwave absorber shifts towards lower side of frequency band with increase in thickness. The complete analysis of the prepared microwave absorbers shows a striking achievement with very low reflection loss and wide absorption bandwidth for all the six compositions in 18-26.5 GHz frequency band.

  8. Towards monitoring of geohazards with ESA's Sentinel-1 C-band SAR data: nationwide feasibility mapping over Great Britain calibrated using ERS-1/2 and ENVISAT PSI data

    NASA Astrophysics Data System (ADS)

    Cigna, Francesca; Bateson, Luke; Dashwood, Claire; Jordan, Colm

    2013-04-01

    Following the success of its predecessors ERS-1/2 and ENVISAT, ESA's Sentinel-1 constellation will provide routine, free of charge and globally-available Synthetic Aperture Radar (SAR) observations of the Earth's surface starting in 2013, with 12day repeat cycle and up to 5m spatial resolution. The upcoming availability of this unprecedented and long-term radar-based observation capacity is stimulating new scientific and operational perspectives within the geohazards and land monitoring community, who initiated and is being working on target preparatory studies to exploit this attractive and rich reservoir of SAR data for, among others, interferometric applications. The Earth and Planetary Observation and Monitoring, and the Shallow Geohazards and Risks Teams of the British Geological Survey (BGS) are routinely assessing new technologies for geohazard mapping, and carrying out innovative research to improve the understanding of landslide processes and their dynamics. Building upon the successful achievements of recent applications of Persistent Scatterer Interferometry (PSI) to geohazards mapping and monitoring in Europe, and with the aim of enhancing further the research on radar EO for landslide management in Britain, since the beginning of 2012 the BGS has been carrying out a research project funded by internal NERC grants aimed at evaluating the potential of these techniques to better understand landslide processes over Great Britain. We mapped the PSI feasibility over the entire landmass, based on the combination of topographic and landuse effects which were modelled by using medium to high resolution DEMs, land cover information from the EEA CORINE Land Cover map 2006, and six PSI datasets over London, Stoke-on-Trent, Bristol/Bath, and the Northumberland-Durham region, made available to BGS through the projects ESA-GMES Terrafirma and EC-FP7 PanGeo. The feasibility maps for the ERS-1/2 and ENVISAT ascending and descending modes showed that topography is not

  9. Influence of the nature of the absorption band on the potential performance of high molar extinction coefficient ruthenium(II) polypyridinic complexes as dyes for sensitized solar cells.

    PubMed

    Gajardo, Francisco; Barrera, Mauricio; Vargas, Ricardo; Crivelli, Irma; Loeb, Barbara

    2011-07-04

    When tested in solar cells, ruthenium polypyridinic dyes with extended π systems show an enhanced light-harvesting capacity that is not necessarily reflected by a high (collected electrons)/(absorbed photons) ratio. Provided that metal-to-ligand charge transfer bands, MLCT, are more effective, due to their directionality, than intraligand (IL) π-π* bands for the electron injection process in the solar cell, it seems important to explore and clarify the nature of the absorption bands present in these types of dyes. This article aims to elucidate if all the absorbed photons of these dyes are potentially useful in the generation of electric current. In other words, their potentiality as dyes must also be analyzed from the point of view of their contribution to the generation of excited states potentially useful for direct injection. Focusing on the assignment of the absorption bands and the nature of the emitting state, a systematic study for a series of ruthenium complexes with 4,4'-distyryl-2,2'-dipyridine (LH) and 4,4'-bis[p-(dimethylamino)-α-styryl]-2,2'-bipyridine (LNMe(2)) "chromophoric" ligands was undertaken. The observed experimental results were complemented with TDDFT calculations to elucidate the nature of the absorption bands, and a theoretical model was proposed to predict the available energy that could be injected from a singlet or a triplet excited state. For the series studied, the results indicate that the percentage of MLCT character to the anchored ligand for the lower energy absorption band follows the order [Ru(deebpy)(2)(LNMe(2))](PF(6))(2) > [Ru(deebpy)(2)(LH)](PF(6))(2) > [Ru(deebpy)(LH)(2)](PF(6))(2), where deebpy is 4,4'-bis(ethoxycarbonyl)-2,2'-bipyridine, predicting that, at least from this point of view, their efficiency as dyes should follow the same trend.

  10. ESA innovation rescues Ultraviolet Observatory

    NASA Astrophysics Data System (ADS)

    1995-10-01

    Astrophysicist Freeman J. Dyson from the Institute for Advanced Studies in Princeton characterizes IUE as "A little half-meter mirror sitting in the sky, unnoticed by the public, pouring out results". By use of the IUE satellite, astronomers obtain access to the ultraviolet radiation of celestial bodies in unique ways not available by any other means, neither from the ground nor by any other spacecraft currently in orbit. IUE serves a wide community of astronomers all over Europe, the United States and many other parts of the world. It allows the acquisition of critical data for fundamental studies of comets and their evaporation when they approach the Sun, of the mechanisms driving the stellar winds which make many stars lose a significant fraction of their mass (before they die slowly as White Dwarfs or in sudden Supernova explosions), as well as in the search to understand the ways in which black holes possibly power the violent nuclei of Active galaxies. One year ago the project was threatened with termination and serious concern was expressed by astronomers about the potential loss of IUE's capabilities, as a result of NASA not continuing to operate the spacecraft. Under the leadership of ESA, the three Agencies involved in the operations of IUE (ESA, NASA and the United Kingdom's Particle Physics and Astronomy Research Council, PPARC), reviewed the operations agreements of the Project. A minor investment allowing the implementation of modern management and engineering techniques as well as a complete revision of the communication infrastructure of the project and continuous improvements in efficiency in the ESA management, also taking advantage of today's technologies, both in computing and communications, have made it possible to continue IUE operations within the financial means available, with ESA taking up most of NASA's share in the operations. According to Dr. Willem Wamsteker, ESA's Dutch IUE Project Scientist, "it was a extremely interesting

  11. Investigation of the optical-absorption bands of Nb4+ and Ti3+ in lithium niobate using magnetic circular dichroism and optically detected magnetic-resonance techniques

    NASA Astrophysics Data System (ADS)

    Reyher, H.-J.; Schulz, R.; Thiemann, O.

    1994-08-01

    The magnetic circular dichroism (MCD) of the absorption of Nb4+Li and Ti3+Li centers in LiNbO3 has been selectively measured by applying optically detected magnetic resonance. The attribution of a well-known broad and unstructured absorption band peaking at 1.6 eV to the Nb4+Li bound small polaron is now unambiguously confirmed. In the MCD spectrum of the isoelectronic Ti3+Li center, bands show up, which closely resemble the MCD bands at 1.6 eV of this bound small polaron. This striking similarity is explained by a cluster model, representing both defects. Either TiLi or NbLi is at the center of this cluster. In both cases, the small polaron is bound to the cluster, and its MCD bands correspond to intervalence transfer transitions within the constituents of the cluster. A study of the spin-orbit coupling of the molecular orbitals of the cluster allows one to analyze the structure of the MCD bands at 2.9 eV of Ti3+Li have no counterpart in the Nb4+Li spectrum. These bands are assigned to transitions to excited states, which are specific to the impurity and are related to the 10Dq transitions known for the crystal field states of a d1 ion.

  12. Self-absorption theory applied to rocket measurements of the nitric oxide (1,0)[gamma] band in the daytime thermosphere

    SciTech Connect

    Eparvier, F.G.; Barth, C.A. )

    1992-09-01

    Sounding rocket observations of the ultraviolet fluorescent emissions of the nitric oxide molecule in the lower thermospheric dayglow are described and analyzed. The rocket experiment was an ultraviolet spectrometer which took limb-viewing spectra of the dayglow between 90- and 185- km altitude in the spectral region from 2120 to 2505 [angstrom] with a resolution of 2.0 [angstrom]. The flight occurred at local noon on March 7, 1989, from Poker Flat, Alaska. Several NO[gamma] bands were visible at all altitudes of the flight, along with emission features of N[sub 2], O[sup +], and N[sup +]. The data for the NO (1,0) and (0,1)[gamma] bands were modeled with optically thin synthetic spectra and used as diagnostics of nitric oxide concentrations. The resonant NO (1,0)[gamma] band emissions were shown to be attenuated at low altitudes relative to the expected emission rates predicted from comparison with the nonresonant (0,1)[gamma] band. Inversion of the optically thin data resulted in a peak nitric oxide concentration of 3.1x10[sup 8] cm[sup [minus]3] at an altitude of 100km. A self-absorption model using Holstein transmission functions was developed and applied to the (1,0) [gamma] band observation. The model results agree with the measured attenuation of the band, indicating the necessity of including self-absorption theory in the analysis of satellite and rocket limb data of NO. The success of the model also confirms the value adopted for the absorption oscillator strength of the (1,0)[gamma] band transition and the instrument calibration.

  13. Critical laser technology developments and ESA space qualification approach in support of ESA's Earth observation missions

    NASA Astrophysics Data System (ADS)

    Zahir, Mustapha; Durand, Yannig

    2011-10-01

    In this paper, ESA's approach to lasers and detectors space evaluation and qualification will be explored. ESA has its own international qualification system, the ESCC system. This system guarantees reliability, assurance and quality of components, and hence a successful space mission. An overview of the ESCC (European Space Component Coordination) system, as well as the relevant ECSS (European Cooperation for Space Standards) related standards addressing components and hybrid qualification will be given. These standards are being constantly updated, through well structured working groups, constantly coming up with new ways of qualifying space components. These components are themselves constantly changing in terms of material, technology, and manufacturing processes. The development of advanced Lidar systems for space applications and their evaluation by airborne or ground based test campaigns is an important strategic element of the ESA Earth Observation Programme. These systems depend on robust and reliable lasers and detector at their core function. Since the early eighties, ESA has been supporting the development of the critical subsystems of any Lidar, i.e. lasers and detectors. Several missions, involving different kinds of lidars, provide the requirements to be addressed in the Lidar risk mitigation activities. They also present a challenge concerning their space qualification and reliability assurance. These missions are: ADM-Aeolus flying ALADIN a Doppler Wind Lidar; EarthCARE embarking ATLID an Atmospheric Backscatter Lidar; three missions studied for their feasibilities: WALES, A-SCOPE and ACCURATE, all using Differential Absorption Lidar in different ways to measure respectively profiles of water vapour, total column of CO2 and greenhouse gases in an occultation geometry.

  14. Euclid - an ESA Medium Class Mission

    NASA Astrophysics Data System (ADS)

    Joachimi, B.

    2016-10-01

    Euclid is an ESA Medium Class mission in the Cosmic Visions program to be launched in 2020. With its 1.2 m telescope, Euclid is going to survey 15,000 deg2 of extragalactic sky in a broad optical band with outstanding image quality fit for weak gravitational lensing measurements. It will also provide near-infrared slitless spectroscopy of more than 107 emission-line galaxies with the main goal of measuring galaxy clustering. Imaging in three near-infrared bands by Euclid will be complemented by ground-based follow-up in optical bands to supply high-quality photometric redshift estimates out to z=2. In combination, its primary cosmological science drivers, weak gravitational lensing and galaxy clustering, will yield unprecedented constraints on the properties of dark matter and dark energy, as well as the validity of Einstein gravity on large scales. Euclid's rich datasets will facilitate further cosmological probes such as statistics of galaxy clusters or the study of galactic dark matter haloes, and a vast array of legacy science. In the following a brief overview on the Euclid mission and its key science is provided.

  15. ESA extends solar observatory mission

    NASA Astrophysics Data System (ADS)

    Zielinski, Sarah

    2006-06-01

    The European Space Agency (ESA) announced on 24 May that it would extend the life of its Solar and Heliospheric Observatory (SOHO) from April 2007 to December 2009. Since it was launched in December 1995, SOHO has provided scientists with a view of the Sun's surface. ``This mission extension will allow SOHO to cement its position as the most important spacecraft in the history of solar physics,'' said SOHO project scientist Bernhard Fleck.

  16. Analysis of Mars surface hydration through the MEx/OMEGA observation of the 3 μm absorption band.

    NASA Astrophysics Data System (ADS)

    Jouglet, D.; Poulet, F.; Bibring, J. P.; Langevin, Y.; Gondet, B.; Milliken, R. E.; Mustard, J. F.

    The near infrared Mars surface global mapping done by OMEGA gives the first opportunity to study the global and detailed characteristics of the 3µm hydration absorption band on Mars surface. This feature is indistinctly due to bending and stretching vibrations of water bound in minerals or adsorbed at their surface, and of hydroxyl groups (for a review, see e.g. [1] or [2]). Its study may give new elements to determine the geologic and climatic past of Mars, and may put new constrain about the current water cycle of Mars. OMEGA data are processed in a pipeline that converts raw data to radiance, removes atmospheric effects and gets I/F. Specific data reduction scheme has been developed to assess temperature of OMEGA spectra at 5 µm and to remove their thermal part so as to get the albedo from 1.µm to 5.1µm ([2]). Two methods, the Integrated Band Depth and the water content based on comparison with laboratory measures of Yen et al. ([3]), have been used to assess the 3µm band depth. These two methods where applied to OMEGA spectra acquired at a nominal calibration level and not exhibiting water ice features. This corresponds to approximately 35 million spectra ([2]). The data processed show the presence of this absorption feature overall the Martian surface, which could be explained by the presence of adsorbed water up to 1% water mass percentage ([4]) and by rinds or coating resulting from weathering (see e.g. [5] or [6]). A possible increase of hydration with albedo is discussed so as to discriminate between the albedo-dependence of the method and hydration variations. Terrains enriched in phyllosilicates ([7]), sulfates ([8]) or hydroxides exhibit an increased hydration at 3 µm. This terrains show that the 3 µm band can bring additional information about composition, for example by observing a variation in the shape of the band. A decrease of hydration with elevation is observed on the processed data independently of the value of albedo. This correlation

  17. Highly vibrationally excited O2 molecules in low-pressure inductively-coupled plasmas detected by high sensitivity ultra-broad-band optical absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Foucher, Mickaël; Marinov, Daniil; Carbone, Emile; Chabert, Pascal; Booth, Jean-Paul

    2015-08-01

    Inductively-coupled plasmas in pure O2 (at pressures of 5-80 mTorr and radiofrequency power up to 500 W) were studied by optical absorption spectroscopy over the spectral range 200-450 nm, showing the presence of highly vibrationally excited O2 molecules (up to vʺ = 18) by Schumann-Runge band absorption. Analysis of the relative band intensities indicates a vibrational temperature up to 10,000 K, but these hot molecules only represent a fraction of the total O2 density. By analysing the (11-0) band at higher spectral resolution the O2 rotational temperature was also determined, and was found to increase with both pressure and power, reaching 900 K at 80 mTorr 500 W. These measurements were achieved using a new high-sensitivity ultra-broad-band absorption spectroscopy setup, based on a laser-plasma light source, achromatic optics and an aberration-corrected spectrograph. This setup allows the measurement of weak broadband absorbances due to a baseline variability lower than 2   ×   10-5 across a spectral range of 250 nm.

  18. Optimal frequency selection of multi-channel O2-band different absorption barometric radar for air pressure measurements

    NASA Astrophysics Data System (ADS)

    Lin, Bing; Min, Qilong

    2017-02-01

    Through theoretical analysis, optimal selection of frequencies for O2 differential absorption radar systems on air pressure field measurements is achieved. The required differential absorption optical depth between a radar frequency pair is 0.5. With this required value and other considerations on water vapor absorption and the contamination of radio wave transmission, frequency pairs of present considered radar system are obtained. Significant impacts on general design of differential absorption remote sensing systems are expected from current results.

  19. Radiative analysis of global mean temperature trends in the middle atmosphere: Effects of non-locality and secondary absorption bands

    NASA Astrophysics Data System (ADS)

    Fomichev, V. I.; Jonsson, A. I.; Ward, W. E.

    2016-02-01

    In this paper, we provide a refined and extended assignment of past and future temperature changes relative to previous analyses and describe and evaluate the relevance of vertical coupling and non-linear and secondary radiative mechanisms for the interpretation of climatic temperature variations in the middle atmosphere. Because of their nature, the latter mechanisms are not adequately accounted for in most regression analyses of temperature trends as a function of local constituent variations. These mechanisms are examined using (1) globally averaged profiles from transient simulations with the Canadian Middle Atmosphere Model (CMAM) forced by changes in greenhouse gases and ozone depleting substances and (2) a one-dimensional radiative-equilibrium model forced using the diagnosed global mean changes in radiatively active constituents as derived from the CMAM model runs. The conditions during the periods 1975 to 1995 and 2010 to 2040 (during which the rates of change in ozone and CO2 differ) provide a suitable contrast for the role of the non-linear and non-local mechanisms being evaluated in this paper to be clearly differentiated and evaluated. Vertical coupling of radiative transfer effects and the influence of secondary absorption bands are important enough to render the results of multiple linear regression analyses between the temperature response and constituent changes misleading. These effects are evaluated in detail using the 1D radiative-equilibrium model using profiles from the CMAM runs as inputs. In order to explain the differences in the CMAM temperature trends prior to and after 2000 these other radiative effects must be considered in addition to local changes in the radiatively active species. The middle atmosphere temperature cools in response to CO2 and water vapor increases, but past and future trends are modulated by ozone changes.

  20. Origin of absorption peaks in reflection loss spectrum in Ku- frequency band of Co-Zr substituted strontium hexaferrites prepared using sucrose precursor

    NASA Astrophysics Data System (ADS)

    Narang, Sukhleen Bindra; Pubby, Kunal; Chawla, S. K.; Kaur, Prabhjyot

    2017-03-01

    This study presents the detailed explanation of the factors, contributing towards the absorption peaks in reflection loss spectrum of hexaferrites. Cobalt-Zirconium substituted strontium hexaferrites, synthesized using sucrose precursor sol-gel technique, were analyzed in 12.4-18 GHz frequency range. The concepts of impedance matching through quarter wavelength condition, complex thickness, dielectric phase angle and attenuation constant have been used to determine the location as well as intensity of absorption peaks. This study also demonstrates the potential application of three compositions of this series with doping content (x)==0.0, 0.6 and 0.8 as an effective microwave absorbers in Ku-frequency band.

  1. Polarization and field dependent two-photon absorption in GaAs/AlGaAs multiquantum well waveguides in the half-band gap spectral region

    NASA Astrophysics Data System (ADS)

    Tsang, H. K.; Penty, R. V.; White, I. H.; Grant, R. S.; Sibbett, W.; Soole, J. B. D.; LeBlanc, H. P.; Andreadakis, N. C.; Colas, E.; Kim, M. S.

    1991-12-01

    We report the observation of two photon absorption which is strongly dependent on the applied electric field and the optical polarization. At 1.55 μm wavelength, the two-photon absorption coefficient of the GaAs/AlGaAs multiquantum well (MQW) waveguides for transverse-magnetic light is about seven times lower than for transverse-electric polarized light and changes by a factor of approximately 4 for a change in applied direct-current electric field of ˜140 kV/cm. Ultrafast nonlinear refraction causing phase changes of over π radians without appreciable excess loss is observed. These measurements demonstrate that GaAs/AlGaAs MQW waveguides could be successfully used for subpicosecond all-optical switching near half-band gap, at wavelengths corresponding to the 1.55 μm optical communications band.

  2. Effects of surface texture and measurement geometry on the near infrared water-of-hydration absorption bands. Implications for the Martian regolith water content.

    NASA Astrophysics Data System (ADS)

    Pommerol, A.; Schmitt, B.

    Near-IR reflectance spectroscopy is widely used to detect mineral hydration on Solar System surfaces by the observation of absorption bands at 1.9 and 3 µm. Recent studies established empirical relationships between the strength of the 3 µm band and the water content of the studied minerals (Milliken et al., 2005). These results have especially been applied to the OMEGA dataset to derive global maps of the Martian regolith water content (Jouglet et al., 2006 and Milliken et al., 2006). However, parameters such as surface texture and measurement geometry are known to have a strong effect on reflectance spectra but their influence on the hydration bands is poorly documented. The aim of this work is the determination of the quantitative effects of particle size, mixing between materials with different albedo and measurement geometry on the absorption bands at 1.9 and 3 µm. We used both an experimental and a modeling approach to study these effects. Bidirectional reflectance spectra were measured for series of well characterized samples (smectite, volcanic tuff and coals, pure and mixed) and modeled with optical constants of a smectite (Roush, 2005). Criteria commonly used to estimate the strength of the bands were then calculated on these spectra. We show that particle size has a strong effect on the 1.9 and 3 µm bands strength, especially for the finest particles (less than 200 µm). Mixing between a fine smectite powder and anthracite powders with various particle sizes (modeled by a synthetic neutral material) highlights the strong effect of the materials albedo on the hydration band estimation criteria. Measurement geometry has a significant effect on the bands strength for high phase angles. Furthermore, the relative variations of band strength with measurement geometry appear very dependent on the surface texture. We will present in details the relationships between these physical parameters and various criteria chosen to estimate the hydration bands

  3. ESA Venus Entry Probe Study

    NASA Technical Reports Server (NTRS)

    vandenBerg, M. L.; Falkner, P.; Phipps, A.; Underwood, J. C.; Lingard, J. S.; Moorhouse, J.; Kraft, S.; Peacock, A.

    2005-01-01

    The Venus Entry Probe is one of ESA s Technology Reference Studies (TRS). The purpose of the Technology Reference Studies is to provide a focus for the development of strategically important technologies that are of likely relevance for future scientific missions. The aim of the Venus Entry Probe TRS is to study approaches for low cost in-situ exploration of Venus and other planetary bodies with a significant atmosphere. In this paper, the mission objectives and an outline of the mission concept of the Venus Entry Probe TRS are presented.

  4. Enhanced Microwave Absorption Properties by Tuning Cation Deficiency of Perovskite Oxides of Two-Dimensional LaFeO3/C Composite in X-Band.

    PubMed

    Liu, Xiang; Wang, Lai-Sen; Ma, Yating; Zheng, Hongfei; Lin, Liang; Zhang, Qinfu; Chen, Yuanzhi; Qiu, Yulong; Peng, Dong-Liang

    2017-03-01

    Development of microwave absorption materials with tunable thickness and bandwidth is particularly urgent for practical applications but remains a great challenge. Here, two-dimensional nanocomposites consisting of perovskite oxides (LaFeO3) and amorphous carbon were successfully obtained through a one pot with heating treatment using sodium chloride as a hard template. The tunable absorption properties were realized by introducing A-site cation deficiency in LaFeO3 perovskite. Among the A-site cation-deficient perovskites, La0.62FeO3/C (L0.62FOC) has the best microwave absorption properties in which the maximum absorption is -26.6 dB at 9.8 GHz with a thickness of 2.94 mm and the bandwidth range almost covers all X-band. The main reason affecting the microwave absorption performance was derived from the A-site cation deficiency which induced more dipoles polarization loss. This work proposes a promising method to tune the microwave absorption performance via introducing deficiency in a crystal lattice.

  5. Quantitative photoluminescence of broad band absorbing melanins: a procedure to correct for inner filter and re-absorption effects

    NASA Astrophysics Data System (ADS)

    Riesz, Jennifer; Gilmore, Joel; Meredith, Paul

    2005-07-01

    We report methods for correcting the photoluminescence emission and excitation spectra of highly absorbing samples for re-absorption and inner filter effects. We derive the general form of the correction, and investigate various methods for determining the parameters. Additionally, the correction methods are tested with highly absorbing fluorescein and melanin (broadband absorption) solutions; the expected linear relationships between absorption and emission are recovered upon application of the correction, indicating that the methods are valid. These procedures allow accurate quantitative analysis of the emission of low quantum yield samples (such as melanin) at concentrations where absorption is significant.

  6. Strong interlayer coupling mediated giant two-photon absorption in MoS e2 /graphene oxide heterostructure: Quenching of exciton bands

    NASA Astrophysics Data System (ADS)

    Sharma, Rituraj; Aneesh, J.; Yadav, Rajesh Kumar; Sanda, Suresh; Barik, A. R.; Mishra, Ashish Kumar; Maji, Tuhin Kumar; Karmakar, Debjani; Adarsh, K. V.

    2016-04-01

    A complex few-layer MoS e2 /graphene oxide (GO) heterostructure with strong interlayer coupling was prepared by a facile hydrothermal method. In this strongly coupled heterostructure, we demonstrate a giant enhancement of two-photon absorption that is in stark contrast to the reverse saturable absorption of a weakly coupled MoS e2 /GO heterostructure and saturable absorption of isolated MoS e2 . Spectroscopic evidence of our study indicates that the optical signatures of isolated MoS e2 and GO domains are significantly modified in the heterostructure, displaying a direct coupling of both domains. Furthermore, our first-principles calculations indicate that strong interlayer coupling between the layers dramatically suppresses the MoS e2 excitonic bands. We envision that our findings provide a powerful tool to explore different optical functionalities as a function of interlayer coupling, which may be essential for the development of device technologies.

  7. Thickness and Composition Tailoring of K- and Ka-Band Microwave Absorption of BaCo x Ti x Fe(12-2 x)O19 Ferrites

    NASA Astrophysics Data System (ADS)

    Narang, Sukhleen Bindra; Pubby, Kunal; Singh, Charanjeet

    2017-02-01

    The goal of this research is to investigate the electromagnetic and microwave absorption properties of M-type barium hexaferrites with chemical formula BaCo x Ti x Fe(12-2 x)O19 ( x = 0.0, 0.2, 0.4, 0.6, 0.8, 1.0) in K and Ka band. Characterization techniques such as x-ray diffraction analysis and scanning electron microscopy were applied to confirm ferrite formation. The frequency dependence of the complex permittivity and complex permeability was studied for prepared ferrite samples in the frequency range from 18 GHz to 40 GHz. Factors such as the quarter-wavelength condition, impedance matching, high dielectric-magnetic losses, as well as ferromagnetic resonance were investigated to determine their contribution to the absorption characteristics. It was found that the quarter-wavelength ( λ/4) model could be successfully applied to predict and understand the position as well as number of reflection peaks in the microwave absorption spectrum. The origin of the reflection loss peaks is explained and verified based on calculations of input impedance, loss tangent, and ferromagnetic resonance. Reflection loss analysis revealed that all six compositions exhibited reflection loss peaks (absorption >90%) at their matching thicknesses and frequencies. Therefore, these ferrites are potential candidates for use in electromagnetic shielding applications requiring low reflectivity in K and Ka band.

  8. A study of the structure of the ν1(HF) absorption band of the СH3СN…HF complex

    NASA Astrophysics Data System (ADS)

    Gromova, E. I.; Glazachev, E. V.; Bulychev, V. P.; Koshevarnikov, A. M.; Tokhadze, K. G.

    2015-09-01

    The ν1(HF) absorption band shape of the CH3CN…HF complex is studied in the gas phase at a temperature of 293 K. The spectra of gas mixtures CH3CN/HF are recorded in the region of 4000-3400 cm-1 at a resolution from 0.1 to 0.005 cm-1 with a Bruker IFS-120 HR vacuum Fourier spectrometer in a cell 10 cm in length with wedge-shaped sapphire windows. The procedure used to separate the residual water absorption allows more than ten fine-structure bands to be recorded on the low-frequency wing of the ν1(HF) band. It is shown that the fine structure of the band is formed primarily due to hot transitions from excited states of the low-frequency ν7 librational vibration. Geometrical parameters of the equilibrium nuclear configuration, the binding energy, and the dipole moment of the complex are determined from a sufficiently accurate quantum-chemical calculation. The frequencies and intensities for a number of spectral transitions of this complex are obtained in the harmonic approximation and from variational solutions of anharmonic vibrational problems.

  9. Complexities in pyroxene compositions derived from absorption band centers: Examples from Apollo samples, HED meteorites, synthetic pure pyroxenes, and remote sensing data

    NASA Astrophysics Data System (ADS)

    Moriarty, D. P.; Pieters, C. M.

    2016-02-01

    We reexamine the relationship between pyroxene composition and near-infrared absorption bands, integrating measurements of diverse natural and synthetic samples. We test an algorithm (PLC) involving a two-part linear continuum removal and parabolic fits to the 1 and 2 μm bands—a computationally simple approach which can easily be automated and applied to remote sensing data. Employing a suite of synthetic pure pyroxenes, the PLC technique is shown to derive similar band centers to the modified Gaussian model. PLC analyses are extended to natural pyroxene-bearing materials, including (1) bulk lunar basalts and pyroxene separates, (2) diverse lunar soils, and (3) HED meteorites. For natural pyroxenes, the relationship between composition and absorption band center differs from that of synthetic pyroxenes. These differences arise from complexities inherent in natural materials such as exsolution, zoning, mixing, and space weathering. For these reasons, band center measurements of natural pyroxene-bearing materials are compositionally nonunique and could represent three distinct scenarios (1) pyroxene with a narrow compositional range, (2) complexly zoned pyroxene grains, or (3) a mixture of multiple pyroxene (or nonpyroxene) components. Therefore, a universal quantitative relationship between band centers and pyroxene composition cannot be uniquely derived for natural pyroxene-bearing materials without additional geologic context. Nevertheless, useful relative relationships between composition and band center persist in most cases. These relationships are used to interpret M3 data from the Humboldtianum Basin. Four distinct compositional units are identified (1) Mare Humboldtianum basalts, (2) distinct outer basalts, (3) low-Ca pyroxene-bearing materials, and (4) feldspathic materials.

  10. Ozone profile retrievals from the ESA GOME instrument

    NASA Technical Reports Server (NTRS)

    Munro, Rosemary; Kerridge, Brian J.; Burrows, John P.; Chance, Kelly

    1994-01-01

    The potential of the ESA Global Ozone Monitoring Experiment (GOME) to produce ozone profile information has been examined by carrying out two sample retrievals using simulated GOME data. The first retrieval examines the potential of the GOME instrument to produce stratospheric ozone profiles using the traditional back-scatter ultraviolet technique, while the second examines the possibility of obtaining tropospheric profile information, and improving the quality of the stratospheric profile retrievals, by exploiting the temperature dependence of the ozone Huggins bands.

  11. ESA's SMART-1 Mission: Status

    NASA Astrophysics Data System (ADS)

    Racca, G.; Foing, B. H.; SMART-1 Project Team

    SMART-1 is the first of Small Missions for Advanced Research and Technology as part of ESA science programme ``Cosmic Vision''. Its objective is to demonstrate Solar Electric Primary Propulsion (SEP) for future Cornerstones (such as Bepi-Colombo) and to test new technologies for spacecraft and instruments. The spacecraft has been launched on 27 sept. 2003, as an Ariane-5 auxiliary passenger. SMART-1 orbit pericenter is now outside the inner radiation belt. The current status of SMART-1 will be given at the symposium. After a 15 month cruise with primary SEP, the SMART-1 mission is to orbit the Moon for a nominal period of six months, with possible extension. The spacecraft will carry out a complete programme of scientific observations during the cruise and in lunar orbit.

  12. ESA announces its Future Science Missions

    NASA Astrophysics Data System (ADS)

    2000-10-01

    The announcement will be made at ESA's Head Office, 8-10 rue Mario Nikis in Paris, during a press breakfast starting at 08:30. Media representatives wishing to attend the event are kindly requested to fill out the attached accreditation from and fax it back to ESA Media Relations Office - Paris. Note to editors The announcement will follow a two-day meeting of ESA's Space Science Committee (SPC), composed of Delegates from all ESA's Member States, in Paris on 11 and 12 October. The SPC will decide - on the basis of the Space Science Advisory Committee's (SSAC) recommendations formulated earlier in September - about the next Cornerstone (CS) and Flexi (F) Missions that will be implemented in the framework of ESA's Horizons 2000 Programme. Further information about the Future Mission candidates and the ESA Science Programme can be found at: http://sci.esa.int. In particular the SSAC recommendations to SPC can be found at: http://sci.esa.int/structure/content/index.cfm?aid=1&cid=2304 Further information on ESA at : http//www.esa.int

  13. Conduction-band electronic states of YbInCu{sub 4} studied by photoemission and soft x-ray absorption spectroscopies

    SciTech Connect

    Utsumi, Yuki; Kurihara, Hidenao; Maso, Hiroyuki; Tobimatsu, Komei; Sato, Hitoshi; Shimada, Kenya; Namatame, Hirofumi; Hiraoka, Koichi; Kojima, Kenichi; Ohkochi, Takuo; Fujimori, Shin-ichi; Takeda, Yukiharu; Saitoh, Yuji; Mimura, Kojiro; Ueda, Shigenori; Yamashita, Yoshiyuki; Yoshikawa, Hideki; Kobayashi, Keisuke; Oguchi, Tamio; Taniguchi, Masaki

    2011-09-15

    We have studied conduction-band (CB) electronic states of a typical valence-transition compound YbInCu{sub 4} by means of temperature-dependent hard x-ray photoemission spectroscopy (HX-PES) of the Cu 2p{sub 3/2} and In 3d{sub 5/2} core states taken at h{nu}=5.95 keV, soft x-ray absorption spectroscopy (XAS) of the Cu 2p{sub 3/2} core absorption region around h{nu}{approx}935 eV, and soft x-ray photoemission spectroscopy (SX-PES) of the valence band at the Cu 2p{sub 3/2} absorption edge of h{nu}=933.0 eV. With decreasing temperature below the valence transition at T{sub V}=42 K, we have found that (1) the Cu 2p{sub 3/2} and In 3d{sub 5/2} peaks in the HX-PES spectra exhibit the energy shift toward the lower binding-energy side by {approx}40 and {approx}30 meV, respectively, (2) an energy position of the Cu 2p{sub 3/2} main absorption peak in the XAS spectrum is shifted toward higher photon-energy side by {approx}100 meV, with an appearance of a shoulder structure below the Cu 2p{sub 3/2} main absorption peak, and (3) an intensity of the Cu L{sub 3}VV Auger spectrum is abruptly enhanced. These experimental results suggest that the Fermi level of the CB-derived density of states is shifted toward the lower binding-energy side. We have described the valence transition in YbInCu{sub 4} in terms of the charge transfer from the CB to Yb 4f states.

  14. Contribution of the transition moments, form of the absorption band, exciton, and the correlation effects in the linear and nonlinear optical properties of conjugated polymers

    NASA Astrophysics Data System (ADS)

    Díaz-Ponce, Javier Alejandro

    2017-04-01

    This work compares the linear and nonlinear optical properties of polyenes and polyenynes. The simulation was made for finite and infinite conjugation of conjugated polymers, such as polyacetylene, β-carotene, bis (p-toluene sulfonate) (PTS) polyenyne, and a short conjugated polyenyne poly-2,6-decadyin-1,6-ylene azelate (PHDAz). The resonance energy and degree of conjugation are determined by fitting the linear absorption spectra. These parameters are then used for calculating the two photon and third-order nonlinear optical properties. The contribution of the transition moment, the form of the absorption band, the exciton, and phonons in the optical properties are determined. The difference of the experimental values is assigned to correlation effects. We found that the exciton, the correlation effects, and the conduction band are more important in the optical properties of polyenynes than of polyenes. In this way, the dependence of the optical properties of polyenynes on the conduction band makes it possible to increase their nonlinear optical properties by interaction with photons (θ ≈ 0). The dependence of the optical properties on the conduction band also produces that the finiteness of the conjugation strongly decreases the optical properties of polyenynes in relation to polyenes with similar conjugation. On the other hand, the phonons are more important in the optical properties of polyenes than of polyenynes. Consequently, the band is indirect for the studied polyenes and direct for the polyenynes. Therefore, the nonlinear optical properties in the resonance frequency of polyenyne PTS are higher than those for polyacetylene. We also found that asymmetric oscillations of χ(3) in the Brillouin zone increases the χ(3) final value in polyenynes. In addition, we found a change of sign of the wave function coefficients by the Peierls distortion of polyenes to become polyenynes, but this change of sign does not affect the optical properties. As a corollary

  15. The Rovibrational Intensities of Five Absorption Bands of (12)C(16)O2 Between 5218 and 5349/cm

    NASA Technical Reports Server (NTRS)

    Giver, Lawrence P.; Brown, Linda R.; Chackerian, Charles, Jr.; Freedman, Richard S.; Gore, Warren J. (Technical Monitor)

    2002-01-01

    Absolute line intensities, band intensities, and Herman-Wallis parameters were measured for the (01(sup 1)2)(sub I) from (00(sup 0)0)(sub I) perpendicular band of (12)C(16)O2 centered at 5315/cm, along with the three nearby associated hot bands: (10(sup 0)2)(sub II) from (01(sup 1)0)(sub I) at 5248/cm, (02(sup 2))(sub I) from (01(sup 1)0)(sub I) at 5291/cm, and (10(sup 0)2)(sub I) from (01(sup 1)0)(sub I) at 5349/cm. The nearby parallel hot band (30(sup 0))(sub I) from (10(sup 0)0)(sub II) at 5218/cm was also included in this study.

  16. ESA uncovers Geminga's `hot spot'

    NASA Astrophysics Data System (ADS)

    2004-07-01

    16 July 2004 Astronomers using ESA’s X-ray observatory XMM-Newton have detected a small, bright ‘hot spot’ on the surface of the neutron star called Geminga, 500 light-years away. The hot spot is the size of a football field and is caused by the same mechanism producing Geminga’s X-ray tails. This discovery identifies the missing link between the X-ray and gamma-ray emission from Geminga. hi-res Size hi-res: 1284 kb Credits: ESA, P. Caraveo (IASF, Milan) Geminga's hot spot This figure shows the effects of charged particles accelerated in the magnetosphere of Geminga. Panel (a) shows an image taken with the EPIC instrument on board the XMM-Newton observatory. The bright tails, made of particles kicked out by Geminga’s strong magnetic field, trail the neutron star as it moves about in space. Panel (b) shows how electrically charged particles interact with Geminga’s magnetic field. For example, if electrons (blue) are kicked out by the star, positrons (in red) hit the star’s magnetic poles like in an ‘own goal’. Panel (c) illustrates the size of Geminga’s magnetic field (blue) compared to that of the star itself at the centre (purple). The magnetic field is tilted with respect to Geminga’s rotation axis (red). Panel (d) shows the magnetic poles of Geminga, where charged particles hit the surface of the star, creating a two-million degrees hot spot, a region much hotter than the surroundings. As the star spins on its rotation axis, the hot spot comes into view and then disappears, causing the periodic colour change seen by XMM-Newton. An animated version of the entire sequence can be found at: Click here for animated GIF [low resolution, animated GIF, 5536 KB] Click here for AVI [high resolution, AVI with DIVX compression, 19128 KB] hi-res Size hi-res: 371 kb Credits: ESA, P. Caraveo (IASF, Milan) Geminga's hot spot, panel (a) Panel (a) shows an image taken with the EPIC instrument on board the XMM-Newton observatory. The bright tails, made of

  17. Safety risk management for ESA space systems

    NASA Astrophysics Data System (ADS)

    Wright, K. M.

    1991-08-01

    ESA's safety program as defined in ESA PSS-01-40, system safety requirements for ESA space systems, comprise the systematic identification and evaluation of space system hazardous characteristics and their associated risks, together with a process of safety optimization through hazard and risk reduction, and implementation verification. This safety optimization and verification process is termed safety risk management. The fundamental principles of safety risk management are discussed.

  18. Water-vapor absorption line measurements in the 940-nm band by using a Raman-shifted dye laser

    NASA Technical Reports Server (NTRS)

    Chu, Zhiping; Wilkerson, Thomas D.; Singh, Upendra N.

    1993-01-01

    We report water-vapor absorption line measurements that are made by using the first Stokes radiation (930-982 nm) with HWHM 0.015/cm generated by a narrow-linewidth, tunable dye laser. Forty-five absorption line strengths are measured with an uncertainty of 6 percent and among them are fourteen strong lines that are compared with previous measurements for the assessment of spectral purity of the light source. Thirty air-broadened linewidths are measured with 8 percent uncertainty at ambient atmospheric pressure with an average of 0.101/cm. The lines are selected for the purpose of temperature-sensitive or temperature-insensitive lidar measurements. Results for these line strengths and linewidths are corrected for broadband radiation and finite laser linewidth broadening effects and compared with the high-resolution transmission molecular absorption.

  19. Broad band nonlinear optical absorption measurements of the laser dye IR26 using white light continuum Z-scan

    NASA Astrophysics Data System (ADS)

    Dey, Soumyodeep; Bongu, Sudhakara Reddy; Bisht, Prem Ballabh

    2017-03-01

    We study the nonlinear optical response of a standard dye IR26 using the Z-scan technique, but with the white light continuum. The continuum source of wavelength from 450 nm to 1650 nm has been generated from the photonic crystal fiber on pumping with 772 nm of Ti:Sapphire oscillator. The use of broadband incident pulse enables us to probe saturable absorption (SA) and reverse saturable absorption (RSA) over the large spectral range with a single Z-scan measurement. The system shows SA in the resonant region while it turns to RSA in the non-resonant regions. The low saturation intensity of the dye can be explained based on the simultaneous excitation from ground states to various higher energy levels with the help of composite energy level diagram. The cumulative effects of excited state absorption and thermal induced nonlinear optical effects are responsible for the observed RSA.

  20. Symmetry-Breaking in Cationic Polymethine Dyes: Part 2. Shape of Electronic Absorption Bands Explained by the Thermal Fluctuations of the Solvent Reaction Field.

    PubMed

    Masunov, Artëm E; Anderson, Dane; Freidzon, Alexandra Ya; Bagaturyants, Alexander A

    2015-07-02

    The electronic absorption spectra of the symmetric cyanines exhibit dramatic dependence on the conjugated chain length: whereas short-chain homologues are characterized by the narrow and sharp absorption bands of high intensity, the long-chain homologues demonstrate very broad, structureless bands of low intensity. Spectra of the intermediate homologues combine both features. These broad bands are often explained using spontaneous symmetry-breaking and charge localization at one of the termini, and the combination of broad and sharp features was interpreted as coexistence of symmetric and asymmetric species in solution. These explanations were not supported by the first principle simulations until now. Here, we employ a combination of time-dependent density functional theory, a polarizable continuum model, and Franck-Condon (FC) approximation to predict the absorption line shapes for the series of 2-azaazulene and 1-methylpyridine-4-substituted polymethine dyes. To simulate inhomogeneous broadening by the solvent, the molecular structures are optimized in the presence of a finite electric field of various strengths. The calculated FC line shapes, averaged with the Boltzmann weights of different field strengths, reproduce the experimentally observed spectra closely. Although the polarizable continuum model accounts for the equilibrium solvent reaction field at absolute zero, the finite field accounts for the thermal fluctuations in the solvent, which break the symmetry of the solute molecule. This model of inhomogeneous broadening opens the possibility for computational studies of thermochromism. The choice of the global hybrid exchange-correlation functional SOGGA11-X, including 40% of the exact exchange, plays the critical role in the success of our model.

  1. Direct Observation of Two-Step Photon Absorption in an InAs/GaAs Single Quantum Dot for the Operation of Intermediate-Band Solar Cells.

    PubMed

    Nozawa, Tomohiro; Takagi, Hiroyuki; Watanabe, Katsuyuki; Arakawa, Yasuhiko

    2015-07-08

    We present the first direct observation of two-step photon absorption in an InAs/GaAs single quantum dot (QD) using photocurrent spectroscopy with two lasers. The sharp peaks of the photocurrent are shifted due to the quantum confined Stark effect, indicating that the photocurrent from a single QD is obtained. In addition, the intensity of the peaks depends on the power of the secondary laser. These results reveal the direct demonstration of the two-step photon absorption in a single QD. This is an essential result for both the fundamental operation and the realization of ultrahigh solar-electricity energy conversion in quantum dot intermediate-band solar cells.

  2. Role of charge separation on two-step two photon absorption in InAs/GaAs quantum dot intermediate band solar cells

    NASA Astrophysics Data System (ADS)

    Creti, A.; Tasco, V.; Cola, A.; Montagna, G.; Tarantini, I.; Salhi, A.; Al-Muhanna, A.; Passaseo, A.; Lomascolo, M.

    2016-02-01

    In this work, we report on the competition between two-step two photon absorption, carrier recombination, and escape in the photocurrent generation mechanisms of high quality InAs/GaAs quantum dot intermediate band solar cells. In particular, the different role of holes and electrons is highlighted. Experiments of external quantum efficiency dependent on temperature and electrical or optical bias (two-step two photon absorption) highlight a relative increase as high as 38% at 10 K under infrared excitation. We interpret these results on the base of charge separation by phonon assisted tunneling of holes from quantum dots. We propose the charge separation as an effective mechanism which, reducing the recombination rate and competing with the other escape processes, enhances the infrared absorption contribution. Meanwhile, this model explains why thermal escape is found to predominate over two-step two photon absorption starting from 200 K, whereas it was expected to prevail at lower temperatures (≥70 K), solely on the basis of the relatively low electron barrier height in such a system.

  3. Visible-light absorption and large band-gap bowing of GaN1-xSbx from first principles

    SciTech Connect

    Sheetz, R. Michael; Richter, Ernst; Andriotis, Antonis N.; Lisenkov, Sergey; Pendyala, Chandrashekhar; Sunkara, Mahendra K.; Menon, Madhu

    2011-08-01

    Applicability of the Ga(Sbx)N1-x alloys for practical realization of photoelectrochemical water splitting is investigated using first-principles density functional theory incorporating the local density approximation and generalized gradient approximation plus the Hubbard U parameter formalism. Our calculations reveal that a relatively small concentration of Sb impurities is sufficient to achieve a significant narrowing of the band gap, enabling absorption of visible light. Theoretical results predict that Ga(Sbx)N1-x alloys with 2-eV band gaps straddle the potential window at moderate to low pH values, thus indicating that dilute Ga(Sbx)N1-x alloys could be potential candidates for splitting water under visible light irradiation.

  4. Visible-light absorption and large band-gap bowing of GaN1-xSbx from first principles

    DOE PAGES

    Sheetz, R. Michael; Richter, Ernst; Andriotis, Antonis N.; ...

    2011-08-01

    Applicability of the Ga(Sbx)N1-x alloys for practical realization of photoelectrochemical water splitting is investigated using first-principles density functional theory incorporating the local density approximation and generalized gradient approximation plus the Hubbard U parameter formalism. Our calculations reveal that a relatively small concentration of Sb impurities is sufficient to achieve a significant narrowing of the band gap, enabling absorption of visible light. Theoretical results predict that Ga(Sbx)N1-x alloys with 2-eV band gaps straddle the potential window at moderate to low pH values, thus indicating that dilute Ga(Sbx)N1-x alloys could be potential candidates for splitting water under visible light irradiation.

  5. Calculating Effect of Point Defects on Optical Absorption Spectra of III-V Semiconductor Superlattices Based on (8x8) k-dot-p Band Structures

    NASA Astrophysics Data System (ADS)

    Huang, Danhong; Iurov, Andrii; Gumbs, Godfrey; Cardimona, David; Krishna, Sanjay

    For a superlattice which is composed of layered zinc-blende structure III-V semiconductor materials, its realistic anisotropic band structures around the Gamma-point are calculated by using the (8x8)k-dot-p method with the inclusion of the self-consistent Hartree potential and the spin-orbit coupling. By including the many-body screening effect, the obtained band structures are further employed to calculate the optical absorption coefficient which is associated with the interband electron transitions. As a result of a reduced quasiparticle lifetime due to scattering with point defects in the system, the self-consistent vertex correction to the optical response function is also calculated with the help of the second-order Born approximation.

  6. Evolution of dielectric function of Al-doped ZnO thin films with thermal annealing: effect of band gap expansion and free-electron absorption.

    PubMed

    Li, X D; Chen, T P; Liu, Y; Leong, K C

    2014-09-22

    Evolution of dielectric function of Al-doped ZnO (AZO) thin films with annealing temperature is observed. It is shown that the evolution is due to the changes in both the band gap and the free-electron absorption as a result of the change of free-electron concentration of the AZO thin films. The change of the electron concentration could be attributed to the activation of Al dopant and the creation/annihilation of the donor-like defects like oxygen vacancy in the thin films caused by annealing.

  7. Predissociation linewidths of the (1,0)-(12,0) Schumann-Runge absorption bands of O2 in the wavelength region 179-202 nm

    NASA Technical Reports Server (NTRS)

    Cheung, A. S.-C.; Yoshino, K.; Esmond, J. R.; Chiu, S. S.-L.; Freeman, D. E.

    1990-01-01

    A nonlinear least-squares method of retrieving predissociation linewidths from the experimental absolute absorption cross sections of Yoshino et al. (1983) has been applied to the (1,0)-(12,0) Schumann-Runge bands of oxygen. The predissociation linewidths deduced are larger than the theoretical predictions of Julienne (1976) and the latest measurements of Lewis et al. (1986). The larger linewidths found will have an impact on calculations of solar flux penetration into the earth atmosphere and of the photodissociation rates of trace species in the upper atmosphere.

  8. ESA's Living Planet Programme: The Earth Explorers

    NASA Astrophysics Data System (ADS)

    Achache, J.

    2003-04-01

    hyperspectral imagers for land monitoring, and from the L-band through TeraHerz frequency range. The intent of the ESA Living Planet Programme is to acquire and apply Explorer mission data for solving fundamental problems in Earth system sciences, such that we can ultimately better preserve the Earth and its environment.

  9. ESA Sentinel-1 Mission and Products

    NASA Astrophysics Data System (ADS)

    Floury, Nicolas; Attema, Evert; Davidson, Malcolm; Levrini, Guido; Rommen, Björn; Rosich, Betlem; Snoeij, Paul

    The global Monitoring for Environment and Security (GMES) space component relies on existing and planned space assets by European States, the European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT), and the European Space Agency (ESA), as well as new complementary developments by ESA. The new developments are implemented in terms of five families of satellites called Sentinels. The Sentinel-1 mission is an imaging synthetic aperture radar (SAR) mission at C-band designed to supply all-weather day-and-night imagery to a number of operational Earth observation based services. Three priorities (fasttrack services) for the mission have been identified by user consultation working groups of the European Union: Marine Core Services, Land Monitoring and Emergency Services. These cover applications such as: - monitoring sea ice zones and the arctic environment, - surveillance of marine environment, - monitoring land surface motion risks, - mapping of land surfaces: forest, water and soil, agriculture, - mapping in support of humanitarian aid in crisis situations. Sentinel-1 has been designed to address medium resolution applications. It includes a main mode of operation that features a wide swath (250 km) and a medium resolution (5 m x 20 m). The two-satellite constellation offers six days exact repeat and the conflict-free operations based on the main operational mode allow exploiting every single data take. This paper describes the Sentinel-1 mission, provides an overview of the mission requirements, and presents some of the key user driven information products, the crucial requirements for operational sustainable services being continuity of data supply, frequent revisit, geographical coverage and timeliness. As data products from the Agency‘s successful ERS-1, ERS-2 and Envisat missions form the basis for many of the pilot GMES services, Sentinel-1 data products need to maintain and in some ways to improve data quality levels of the Agency

  10. Swarm: ESA's Magnetic Field Mission

    NASA Astrophysics Data System (ADS)

    Drinkwater, M. R.; Haagmans, R.; Floberghagen, R.; Plank, G.; Menard, Y.

    2011-12-01

    Swarm is the fifth Earth Explorer mission in ESA's Living Planet Programme, and is scheduled for launch in 2012. The objective of the Swarm mission is to provide the best-ever survey of the geomagnetic field and its temporal evolution using a constellation of 3 identical satellites. The Mission shall deliver data that allow access to new insights into the Earth system by improved scientific understanding of the Earth's interior and near-Earth electromagnetic environment. After launch and triple satellite release at an initial altitude of about 490 km, a pair of the satellites will fly side-by-side with slowly decaying altitude, while the third satellite will be lifted to 530 km to complete the Swarm constellation. High-precision and high-resolution measurements of the strength, direction and variation of the magnetic field, complemented by precise navigation, accelerometer and electric field measurements, will provide the observations required to separate and model various sources of the geomagnetic field and near-Earth current systems. The mission science goals are to provide a unique view into Earth core dynamics, mantle conductivity, crustal magnetisation, ionospheric and magnetospheric current systems and upper atmosphere dynamics - ranging from understanding the geodynamo to contributing to space weather. The scientific objectives and results from recent scientific studies will be presented. In addition the current status of the project, which is presently approaching the final stage of the development phase, will be addressed. A consortium of European scientific institutes is developing a distributed processing system to produce geophysical (Level 2) data products to the Swarm user community. The setup of Swarm ground segment and the contents of the data products will be addressed. More information on the Swarm mission can be found at the mission web site (see URL below).

  11. Golden legacy from ESA's observatory

    NASA Astrophysics Data System (ADS)

    2003-07-01

    'milestone number' of 1000 scientific papers was reached. Even now ISO's data archive remains a valuable source of new results. For example, some of the latest papers describe the detection of water in 'protostars', which are stars in the process of being born, and studies of numerous nearby galaxies. "Of course we were confident ISO was going to do very well, but its actual productivity has been far beyond our expectations. The publication rate does not even seem to have peaked yet! We expect many more results," Salama says. Note for editors ISO's data archive contains scientific data from about 30 000 observations. Astronomers from all over the world have downloaded almost eight times the equivalent of the entire scientific archive. As much as 35% of all ISO observations have already been published at least once in prestigious scientific journals. ESA is now preparing to continue its infrared investigation of the Universe. The next generation of infrared space observatories is already in the pipeline. ISO is to be followed by the NASA SIRTF observatory to be launched later this year. Then, in 2007, ESA will follow up the pioneering work of ISO with the Herschel Space Observatory, which will become the largest imaging telescope ever put into space. ISO The Infrared Space Observatory (ISO) was launched in 1995 and operated from November that year to May 1998, when it ran out of the coolant needed to keep its detectors working. At the time it was the most sensitive infrared satellite ever launched and made particularly important studies of the dusty regions of the Universe, where visible light telescopes can see nothing. ESA will reopen its examination of the infrared Universe when Herschel is launched in 2007. Herschel Herschel will be the largest space telescope when, in 2007, it is launched on an Ariane-5 rocket, together with ESA’s cosmology mission, Planck. Herschel’s 3.5-metre diameter mirror will collect longwave infrared radiation from some of the coolest and most

  12. Sub-Band Gap Absorption in As-Deposited and Annealed nc-CdSe Thin Films Using Constant Photocurrent Method (CPM)

    NASA Astrophysics Data System (ADS)

    Sharma, Kriti; Al-Kabbi, A. S.; Singh, Baljinder; Saini, G. S. S.; Tripathi, S. K.

    2011-12-01

    Nanocrystalline CdSe thin films have been prepared by thermal vaccum evaporation technique using Inert Gas Condensation method using Argon as inert gas. XRD confirms the crystalline cubic nature of nc-CdSe thin films. The optical band gap is calculated for as deposited nc-CdSe and it comes out to be 2.1 eV. CPM has been used to measure sub-band gap absorption in nanocrystalline CdSe thin films. The thin films of nc-CdSe have been annealed at 80 °C for one hour and sub-bandgap absorption in annealed samples has also been calculated. Slope of Urbach tail which is a measure of disorder in both as deposited and annealed samples has been calculated. In the case of as deposited nc-CdSe thin films, Urbach slope is 354 meV. It decreases to the value 198 meV after annealing which shows structural disorder decreases after annealing.

  13. High energy electron irradiation of interstellar carbonaceous dust analogs: Cosmic ray effects on the carriers of the 3.4 µm absorption band.

    PubMed

    Maté, Belén; Molpeceres, Germán; Jiménez-Redondo, Miguel; Tanarro, Isabel; Herrero, Víctor J

    2016-11-01

    The effects of cosmic rays on the carriers of the interstellar 3.4 μm absorption band have been investigated in the laboratory. This band is attributed to stretching vibrations of CH3 and CH2 in carbonaceous dust. It is widely observed in the diffuse interstellar medium (ISM), but disappears in dense clouds. Destruction of CH3 and CH2 by cosmic rays could become relevant in dense clouds, shielded from the external ultraviolet field. For the simulations, samples of hydrogenated amorphous carbon (a-C:H) have been irradiated with 5 keV electrons. The decay of the band intensity vs electron fluence reflects a-C:H dehydrogenation, which is well described by a model assuming that H2 molecules, formed by the recombination of H atoms liberated through CH bond breaking, diffuse out of the sample. The CH bond destruction rates derived from the present experiments are in good accordance with those from previous ion irradiation experiments of HAC. The experimental simplicity of electron bombardment has allowed the use of higher energy doses than in the ion experiments. The effects of cosmic rays on the aliphatic components of cosmic dust are found to be small. The estimated cosmic ray destruction times for the 3.4 μm band carriers lie in the 10(8) yr range and cannot account for the disappearance of this band in dense clouds, which have characteristic lifetimes of 3 × 10(7) yr. The results invite a more detailed investigation of the mechanisms of CH bond formation and breaking in the intermediate region between diffuse and dense clouds.

  14. High energy electron irradiation of interstellar carbonaceous dust analogs: Cosmic ray effects on the carriers of the 3.4 µm absorption band

    PubMed Central

    Maté, Belén; Molpeceres, Germán; Jiménez-Redondo, Miguel; Tanarro, Isabel; Herrero, Víctor J.

    2017-01-01

    The effects of cosmic rays on the carriers of the interstellar 3.4 μm absorption band have been investigated in the laboratory. This band is attributed to stretching vibrations of CH3 and CH2 in carbonaceous dust. It is widely observed in the diffuse interstellar medium (ISM), but disappears in dense clouds. Destruction of CH3 and CH2 by cosmic rays could become relevant in dense clouds, shielded from the external ultraviolet field. For the simulations, samples of hydrogenated amorphous carbon (a-C:H) have been irradiated with 5 keV electrons. The decay of the band intensity vs electron fluence reflects a-C:H dehydrogenation, which is well described by a model assuming that H2 molecules, formed by the recombination of H atoms liberated through CH bond breaking, diffuse out of the sample. The CH bond destruction rates derived from the present experiments are in good accordance with those from previous ion irradiation experiments of HAC. The experimental simplicity of electron bombardment has allowed the use of higher energy doses than in the ion experiments. The effects of cosmic rays on the aliphatic components of cosmic dust are found to be small. The estimated cosmic ray destruction times for the 3.4 μm band carriers lie in the 108 yr range and cannot account for the disappearance of this band in dense clouds, which have characteristic lifetimes of 3 × 107 yr. The results invite a more detailed investigation of the mechanisms of CH bond formation and breaking in the intermediate region between diffuse and dense clouds. PMID:28133388

  15. High-energy Electron Irradiation of Interstellar Carbonaceous Dust Analogs: Cosmic-ray Effects on the Carriers of the 3.4 μm Absorption Band

    NASA Astrophysics Data System (ADS)

    Maté, Belén; Molpeceres, Germán; Jiménez-Redondo, Miguel; Tanarro, Isabel; Herrero, Víctor J.

    2016-11-01

    The effects of cosmic rays on the carriers of the interstellar 3.4 μm absorption band have been investigated in the laboratory. This band is attributed to stretching vibrations of CH3 and CH2 in carbonaceous dust. It is widely observed in the diffuse interstellar medium, but disappears in dense clouds. Destruction of CH3 and CH2 by cosmic rays could become relevant in dense clouds, shielded from the external ultraviolet field. For the simulations, samples of hydrogenated amorphous carbon (a-C:H) have been irradiated with 5 keV electrons. The decay of the band intensity versus electron fluence reflects a-C:H dehydrogenation, which is well described by a model assuming that H2 molecules, formed by the recombination of H atoms liberated through CH bond breaking, diffuse out of the sample. The CH bond destruction rates derived from the present experiments are in good accordance with those from previous ion irradiation experiments of HAC. The experimental simplicity of electron bombardment has allowed the use of higher-energy doses than in the ion experiments. The effects of cosmic rays on the aliphatic components of cosmic dust are found to be small. The estimated cosmic-ray destruction times for the 3.4 μm band carriers lie in the 108 yr range and cannot account for the disappearance of this band in dense clouds, which have characteristic lifetimes of 3 × 107 yr. The results invite a more detailed investigation of the mechanisms of CH bond formation and breaking in the intermediate region between diffuse and dense clouds.

  16. Microwave absorption properties of LiNb3O8 in X-band prepared by combustion synthesis

    NASA Astrophysics Data System (ADS)

    Goud, J. Pundareekam; Sindam, Bashaiah; Tumuluri, Anil; Raju, K. C. James

    2015-08-01

    Single phase LiNb3O8 powders were prepared using combustion synthesis technique. The powders were prepared by heat treating Li2CO3+Nb2O5/urea mixture in 1:3 ratio. Structural and morphological details have been done to confirm the presence of LiNb3O8. The S-parameters were measured using rectangular waveguide method in the X-band frequency (8.2GHz to 12.4GHz) by Vector Network Analyzer. The dielectric characteristics like dielectric constant (ɛ') and dielectric loss (ɛ″) were calculated using Nicolson-Ross-Weir algorithm. Complex permittivity of 28-0.2j and 26-1.0j at 8.2GHz and 12.4GHz respectively are observed. Reflection loss was derived with permittivity and permeability as input parameters. Microwave absorber thickness is optimized and the RL< -20dB is obtained in the X-band frequency.

  17. Uniform Supersonic Expansion for FTIR Absorption Spectroscopy: The nu(5) Band of (NO)(2) at 26 K.

    PubMed

    Benidar; Georges; Le Doucen R; Boissoles; Hamon; Canosa; Rowe

    2000-01-01

    A high-resolution Fourier transform interferometer (Bruker IFS 120 HR) was combined with a uniform supersonic expansion produced by means of axisymmetric Laval nozzles. The geometry profile of the nozzle enabled us to work under precise thermodynamic and kinetic conditions. The effect of the cooling rate of different nozzles on cluster nucleation is illustrated. The experimental sensitivity was tested by recording the nu(5) band of (NO)(2) at 26 K. Copyright 2000 Academic Press.

  18. A Multi-Band Analytical Algorithm for Deriving Absorption and Backscattering Coefficients from Remote-Sensing Reflectance of Optically Deep Waters

    NASA Technical Reports Server (NTRS)

    Lee, Zhong-Ping; Carder, Kendall L.

    2001-01-01

    A multi-band analytical (MBA) algorithm is developed to retrieve absorption and backscattering coefficients for optically deep waters, which can be applied to data from past and current satellite sensors, as well as data from hyperspectral sensors. This MBA algorithm applies a remote-sensing reflectance model derived from the Radiative Transfer Equation, and values of absorption and backscattering coefficients are analytically calculated from values of remote-sensing reflectance. There are only limited empirical relationships involved in the algorithm, which implies that this MBA algorithm could be applied to a wide dynamic range of waters. Applying the algorithm to a simulated non-"Case 1" data set, which has no relation to the development of the algorithm, the percentage error for the total absorption coefficient at 440 nm a (sub 440) is approximately 12% for a range of 0.012 - 2.1 per meter (approximately 6% for a (sub 440) less than approximately 0.3 per meter), while a traditional band-ratio approach returns a percentage error of approximately 30%. Applying it to a field data set ranging from 0.025 to 2.0 per meter, the result for a (sub 440) is very close to that using a full spectrum optimization technique (9.6% difference). Compared to the optimization approach, the MBA algorithm cuts the computation time dramatically with only a small sacrifice in accuracy, making it suitable for processing large data sets such as satellite images. Significant improvements over empirical algorithms have also been achieved in retrieving the optical properties of optically deep waters.

  19. ESA Fire CCI product assessment

    NASA Astrophysics Data System (ADS)

    Heil, Angelika; Yue, Chao; Mouillot, Florent; Storm, Thomas; Chuvieco, Emilio; Kaiser, Johannes

    2016-04-01

    Vegetation fires are a major disturbance in the Earth System. Fires change the biophysical properties and dynamics of ecosystems and alter terrestrial carbon pools. By altering the atmosphere's composition, fire emissions exert a significant climate forcing. To realistically model past and future changes of the Earth System, fire disturbances must be taken into account. Related modelling efforts require consistent global burned area observations covering at least 10 to 20 years. Guided by the specific requirements of a wide range of end users, the ESA fire_cci project is currently computing a new global burned area dataset. It applies a newly developed spectral change detection algorithm upon the full ENVISAT-MERIS archive (2002 to 2012). The algorithm relies on MODIS active fire information as "seed". A first, formally validated version has been released for the period 2006 to 2008. It comprises a pixel burned area product (spatial resolution of 333 m) with date detection information and a biweekly grid product at 0.5 degree spatial resolution. We compare fire_cci burned area with other global burned area products (MCD64, GFED4(s), GEOLAND) and a set of active fires data (hotspots from MODIS, TRMM, AATSR and fire radiative power from GFAS). Output from the ongoing processing of the full MERIS timeseries will be incorporated into the study, as far as available. The analysis of patterns of agreement and disagreement between fire_cci and other products provides a better understanding of product characteristics and uncertainties. The intercomparison of the 2006-2008 fire_cci time series shows a close agreement with GFED4 data in terms of global burned area and the general spatial and temporal patterns. Pronounced differences, however, emerge for specific regions or fire events. Burned area mapped by fire_cci tends to be notably higher in regions where small agricultural fires predominate. The improved detection of small agricultural fires by fire_cci can be related to

  20. CarbonSat: ESA's Earth Explorer 8 Candidate Mission

    NASA Astrophysics Data System (ADS)

    Meijer, Y. J.; Ingmann, P.; Löscher, A.

    2012-04-01

    exploit a passive observing technique measuring scattered solar light with imaging spectrometers. It will perform measurements of CO2 and CH4 in combination with O2 to yield their dry column amounts. Spectral absorptions of CO2 in the 1.6 μm and 2 μm bands, O2 in the 760 nm and CH4 in the 1.65 μm spectral ranges measured with high spectral resolution of the order of between 0.03 and 0.3 nm and a high signal-to-noise ratio. The CarbonSat mission concept builds on the heritage and lessons learned from SCIAMACHY, GOSAT and OCO(-2) to make strategically important measurements of the amounts and distribution of CO2 and CH4 in the context of Climate Change.

  1. Efficient tissue ablation using a laser tunable in the water absorption band at 3 microns with little collateral damage

    NASA Astrophysics Data System (ADS)

    Nierlich, Alexandra; Chuchumishev, Danail; Nagel, Elizabeth; Marinova, Kristiana; Philipov, Stanislav; Fiebig, Torsten; Buchvarov, Ivan; Richter, Claus-Peter

    2014-03-01

    Lasers can significantly advance medical diagnostics and treatment. At high power, they are typically used as cutting tools during surgery. For lasers that are used as knifes, radiation wavelengths in the far ultraviolet and in the near infrared spectral regions are favored because tissue has high contents of collagen and water. Collagen has an absorption peak around 190 nm, while water is in the near infrared around 3,000 nm. Changing the wavelength across the absorption peak will result in significant differences in laser tissue interactions. Tunable lasers in the infrared that could optimize the laser tissue interaction for ablation and/or coagulation are not available until now besides the Free Electron Laser (FEL). Here we demonstrate efficient tissue ablation using a table-top mid-IR laser tunable between 3,000 to 3,500 nm. A detailed study of the ablation has been conducted in different tissues. Little collateral thermal damage has been found at a distance above 10-20 microns from the ablated surface. Furthermore, little mechanical damage could be seen in conventional histology and by examination of birefringent activity of the samples using a pair of cross polarizing filters.

  2. Absolute Absorption Intensities in the Fundamental nu2 and nu5 Bands of 12CH3F.

    PubMed

    Lepère; Blanquet; Walrand; Tarrago

    1998-06-01

    The absolute strengths of 93 lines belonging to the nu2 and nu5 bands of methyl fluoride were measured in the range of 1416-1503 cm-1 using a tunable diode-laser (TDL) spectrometer. These experimental line intensities were obtained from the equivalent width method. The intensities were analyzed within a dyad system, required to account properly for the strong Coriolis coupling between nu2 and nu5. The fit to the experimental data led to the determination of the dipole moment derivatives partial differentialµ/ partial differentialq2 and partial differentialµ/ partial differentialq5, as well as the first-order Herman-Wallis correction in K to partial differentialµ/ partial differentialq5. The intensities were reproduced with an overall standard deviation of 1.44%, to be compared with a mean experimental uncertainty equal to 1.58%. The values derived for the vibrational band strengths of nu2 and nu5 are 2.124 (18) cm-2.atm-1 and 36.96 cm-2.atm-1 at 296 K, respectively. Copyright 1998 Academic Press.

  3. Antenna pointing mechanism for ESA ENVISAT polar platform

    NASA Technical Reports Server (NTRS)

    Serrano, J.; SanMillan, J.; Santiago, R.

    1996-01-01

    INTA is currently developing a two-degree-of-freedom antenna pointing mechanism (APM) as part of the ESA ENVISAT POLAR PLATFORM (PPF) program. This mechanism will drive a Ka-band antenna within the Data-Relay Satellite System (DRS) on board the Polar Platform satellite. The first mission using PPF is ENVISAT, which is expected to be flown in 1998. This paper describes the main requirements, design, and test results of this pointing system, as well as the main technical problems from customer requirements and how those have been faced to achieve a final design.

  4. Ion irradiation of carbonaceous interstellar analogues. Effects of cosmic rays on the 3.4 μm interstellar absorption band

    NASA Astrophysics Data System (ADS)

    Godard, M.; Féraud, G.; Chabot, M.; Carpentier, Y.; Pino, T.; Brunetto, R.; Duprat, J.; Engrand, C.; Bréchignac, P.; D'Hendecourt, L.; Dartois, E.

    2011-05-01

    Context. A 3.4 μm absorption band (around 2900 cm-1), assigned to aliphatic C-H stretching modes of hydrogenated amorphous carbons (a-C:H), is widely observed in the diffuse interstellar medium, but disappears or is modified in dense clouds. This spectral difference between different phases of the interstellar medium reflects the processing of dust in different environments. Cosmic ray bombardment is one of the interstellar processes that make carbonaceous dust evolve. Aims: We investigate the effects of cosmic rays on the interstellar 3.4 μm absorption band carriers. Methods: Samples of carbonaceous interstellar analogues (a-C:H and soot) were irradiated at room temperature by swift ions with energy in the MeV range (from 0.2 to 160 MeV). The dehydrogenation and chemical bonding modifications that occurred during irradiation were studied with IR spectroscopy. Results: For all samples and all ions/energies used, we observed a decrease of the aliphatic C-H absorption bands intensity with the ion fluence. This evolution agrees with a model that describes the hydrogen loss as caused by the molecular recombination of two free H atoms created by the breaking of C-H bonds by the impinging ions. The corresponding destruction cross section and asymptotic hydrogen content are obtained for each experiment and their behaviour over a large range of ion stopping powers are inferred. Using elemental abundances and energy distributions of galactic cosmic rays, we investigated the implications of these results in different astrophysical environments. The results are compared to the processing by UV photons and H atoms in different regions of the interstellar medium. Conclusions: The destruction of aliphatic C-H bonds by cosmic rays occurs in characteristic times of a few 108 years, and it appears that even at longer time scales, cosmic rays alone cannot explain the observed disappearance of this spectral signature in dense regions. In diffuse interstellar medium, the formation

  5. Christmas on Mars: be there with ESA

    NASA Astrophysics Data System (ADS)

    2003-12-01

    The exciting event can be followed at ESA’s European Space Operations Centre (ESOC) in Darmstadt, Germany, on Thursday, 25 December, from 01:30 to 14:00, together with the mission managers, the operation teams, scientists and top ESA management, including ESA’s Director-General Jean-Jacques Dordain, ESA’s Director of Science David Southwood and ESA’s Director of Technical and Operational Support Gaele Winters. The highlights of the night will be also webcast over the internet http://mars.esa.int. As well as live streaming of key events, the Mars Express site will have daily news, features, images, videos and more. The ESA TV Service will provide live coverage of operations, from the Operations Control Centre at ESOC. All transmission and satellite details are published online at http://television.esa.int All live transmissions are also carried free-to-air on Astra 2 C at 19 degrees East, transponder 57, horizontal, (DVB-MPEG-2), frequency 10832 MHz, Symbol Rate 22000 MS/sec, FEC 5/6. The service name is ESA Media wishing to attend are asked to complete the attached reply form and fax it back to ESA Media Relations Service: +33 (0)1 53 69 76 90.

  6. First laboratory detection of an absorption line of the first overtone electric quadrupolar band of N2 by CRDS near 2.2 μm

    NASA Astrophysics Data System (ADS)

    Čermák, P.; Vasilchenko, S.; Mondelain, D.; Kassi, S.; Campargue, A.

    2017-01-01

    The extremely weak 2-0 O(14) electric quadrupole transition of N2 has been detected by very high sensitivity Cavity Ring Down spectroscopy near 4518 cm-1. It is the first N2 absorption line in the first overtone band reported so far from laboratory experiments. By combining a feedback narrowed Distributed Feedback laser diode with a passive cell tracking technique, a limit of detection of αmin ∼ 1.2 × 10-11 cm-1 was achieved after one day of spectra averaging. The N2 2-0 O(14) line position and line intensity (about 1.5 × 10-30 cm/molecule) agree with calculated values provided in the HITRAN2012 database.

  7. Confinement effect of laser ablation plume in liquids probed by self-absorption of C{sub 2} Swan band emission

    SciTech Connect

    Sakka, Tetsuo; Saito, Kotaro; Ogata, Yukio H.

    2005-01-01

    The (0,0) Swan band of the C{sub 2} molecules in a laser ablation plume produced on the surface of graphite target submerged in water was used as a probe to estimate the density of C{sub 2} molecules in the plume. Observed emission spectra were reproduced excellently by introducing a self-absorption parameter to the theoretical spectral profile expected by a rotational population distribution at a certain temperature. The optical density of the ablation plume as a function of time was determined as a best-fit parameter by the quantitative fitting of the whole spectral profile. The results show high optical densities for the laser ablation plume in water compared with that in air. It is related to the plume confinement or the expansion, which are the important phenomena influencing the characteristics of laser ablation plumes in liquids.

  8. Tentative identification of the 780/cm nu-4 band Q branch of chlorine nitrate in high-resolution solar absorption spectra of the stratosphere

    NASA Technical Reports Server (NTRS)

    Rinsland, C. P.; Goldman, A.; Murcray, D. G.; Murcray, F. J.; Malathy Devi, V.

    1985-01-01

    According to models of the photochemistry of the stratosphere, chlorine nitrate (ClONO2) is an important temporary reservoir of stratospheric chlorine. At night, ClO is believed to combine in a three-body reaction with NO2 to form chlorine nitrate. During daylight, chlorine nitrate is destroyed by photolysis to form free chlorine and NO3. Infrared spectroscopy has the potential to provide a technique for conducting important quantitative measurements of stratospheric chlorine nitrate. The present paper reports a detailed study of spectra in the 780/cm region. This study has led to the tentative identification of the nu-4 band Q branch of ClONO2 as a significant contributor to the observed stratospheric absorption near 780.21 per cm.

  9. ESA airborne campaigns in support of Earth Explorers

    NASA Astrophysics Data System (ADS)

    Casal, Tania; Davidson, Malcolm; Schuettemeyer, Dirk; Perrera, Andrea; Bianchi, Remo

    2013-04-01

    In the framework of its Earth Observation Programmes the European Space Agency (ESA) carries out ground based and airborne campaigns to support geophysical algorithm development, calibration/validation, simulation of future spaceborne earth observation missions, and applications development related to land, oceans and atmosphere. ESA has been conducting airborne and ground measurements campaigns since 1981 by deploying a broad range of active and passive instrumentation in both the optical and microwave regions of the electromagnetic spectrum such as lidars, limb/nadir sounding interferometers/spectrometers, high-resolution spectral imagers, advanced synthetic aperture radars, altimeters and radiometers. These campaigns take place inside and outside Europe in collaboration with national research organisations in the ESA member states as well as with international organisations harmonising European campaign activities. ESA campaigns address all phases of a spaceborne missions, from the very beginning of the design phase during which exploratory or proof-of-concept campaigns are carried out to the post-launch exploitation phase for calibration and validation. We present four recent campaigns illustrating the objectives and implementation of such campaigns. Wavemill Proof Of Concept, an exploratory campaign to demonstrate feasibility of a future Earth Explorer (EE) mission, took place in October 2011 in the Liverpool Bay area in the UK. The main objectives, successfully achieved, were to test Astrium UKs new airborne X-band SAR instrument capability to obtain high resolution ocean current and topology retrievals. Results showed that new airborne instrument is able to retrieve ocean currents to an accuracy of ± 10 cms-1. The IceSAR2012 campaign was set up to support of ESA's EE Candidate 7,BIOMASS. Its main objective was to document P-band radiometric signatures over ice-sheets, by upgrading ESA's airborne POLARIS P-band radar ice sounder with SAR capability. Campaign

  10. meso-meso linked porphyrin-[26]hexaphyrin-porphyrin hybrid arrays and their triply linked tapes exhibiting strong absorption bands in the NIR region.

    PubMed

    Mori, Hirotaka; Tanaka, Takayuki; Lee, Sangsu; Lim, Jong Min; Kim, Dongho; Osuka, Atsuhiro

    2015-02-11

    We describe the synthesis and characterization of directly meso-meso linked porphyrin-[26]hexaphyrin-porphyrin hybrid oligomers and their triply linked (completely fused) hybrid tapes. meso-meso Linked Ni(II) porphyrin-[26]hexaphyrin-Ni(II) porphyrin trimers were prepared by methanesulfonic acid-catalyzed cross-condensation of meso-formyl Ni(II) porphyrins with a 5,10-diaryltripyrrane followed by oxidation with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ). The Ni(II) porphyrin moieties were converted to Zn(II) porphyrins via an indirect route involving reduction of the [26]hexaphyrin to its 28π congener, acid-induced denickelation, oxidation of the [28]hexaphyrin, and finally Zn(II) ion insertion. Over the course of these transformations, porphyrin-[28]hexaphyrin-porphyrin trimers have been revealed to take on a Möbius aromatic twisted structure for the [28]hexaphyrin segment. Oxidation of meso-meso linked hybrid trimer bearing 5,15-diaryl Zn(II) porphyrins with DDQ/Sc(OTf)3 under mild conditions resulted in meso-meso coupling oligomerization, affording the corresponding dimeric (hexamer), trimeric (nonamer), and tetrameric (dodecamer) oligomers. On the other hand, oxidation of a meso-meso linked hybrid trimer bearing 5,10,15-triaryl Zn(II) porphyrin terminals with DDQ/Sc(OTf)3 under harsher conditions afforded a meso-meso, β-β, β-β triply linked hybrid porphyrin tape, which displays a sharp and intense absorption band at 1912 nm. Comparison of this extremely red-shifted absorption band with those of Zn(II) porphyrin tapes suggests that the bathochromic-shifting capability of a [26]hexaphyrin unit is large, almost equivalent to that of four individual Zn(II) porphyrin units. As demonstrated, the fusion of porphyrins to [26]hexaphyrin offers an efficient means to expand their conjugation networks, significantly expanding the capabilities attainable for these chromophores.

  11. Microwave absorption in X and Ku band frequency of cotton fabric coated with Ni-Zn ferrite and carbon formulation in polyurethane matrix

    NASA Astrophysics Data System (ADS)

    Gupta, K. K.; Abbas, S. M.; Goswami, T. H.; Abhyankar, A. C.

    2014-08-01

    The present study highlights various microwave properties, i.e. reflection, transmission, absorption and reflection loss, of the coated cotton fabric [formulation: Ni-Zn ferrite (Ni 0.5Zn0.5Fe2O4) and carbon black (acetylene black) at concentrations of 30, 40, 50, 60 and70 g of ferrite and 5 g carbon in each 100 ml polyurethane] evaluated at 8-18 GHz frequency. The uniform density of filling materials in coated fabrics (dotted marks in SEM micrograph) indicates homogeneous dispersion of conducting fillers in polyurethane and the density of filling material cluster increases with increase in ferrite concentration. SEM images also show uniform coating of conducting fillers/resin system over individual fibers and interweave spaces. The important parameters governing the microwave properties of coated fabrics i.e. permittivity and permeability, S-parameters, reflection loss, etc. were studied in a HVS free space microwave measurement system. The lossy character of coated fabric is found to increase with increase of ferrite content; the ferrite content decreases the impedance and increases the permittivity and permeability values. The 1.6-1.8 mm thick coated fabric sample (40 wt% ferrite, 3 wt% carbon and 57 wt% PU) has shown about 40% absorption, 20% transmission and 40% reflectance in X (8.2-12.4 GHz) and Ku (12-18 GHz) frequency bands. The reflection loss at 13.5 GHz has shown the highest peak value (22.5 dB) due to coated sample optical thickness equal to λ/4 and more than 7.5 dB in entire Ku band. Owing to its thin and flexible nature, the coated fabric can be used as apparel in protecting human being from hazardous microwaves and also as radar camouflage covering screen in defense.

  12. Optimization of absorption bands of dye-sensitized and perovskite tandem solar cells based on loss-in-potential values.

    PubMed

    Sobuś, Jan; Ziółek, Marcin

    2014-07-21

    A numerical study of optimal bandgaps of light absorbers in tandem solar cell configurations is presented with the main focus on dye-sensitized solar cells (DSSCs) and perovskite solar cells (PSCs). The limits in efficiency and the expected improvements of tandem structures are investigated as a function of total loss-in-potential (V(L)), incident photon to current efficiency (IPCE) and fill factor (FF) of individual components. It is shown that the optimal absorption onsets are significantly smaller than those derived for multi-junction devices. For example, for double-cell devices the onsets are at around 660 nm and 930 nm for DSSCs with iodide based electrolytes and at around 720 nm and 1100 nm for both DSSCs with cobalt based electrolytes and PSCs. Such configurations can increase the total sunlight conversion efficiency by about 35% in comparison to single-cell devices of the same VL, IPCE and FF. The relevance of such studies for tandem n-p DSSCs and for a proposed new configuration for PSCs is discussed. In particular, it is shown that maximum total losses of 1.7 V for DSSCs and 1.4 V for tandem PSCs are necessary to give any efficiency improvement with respect to the single bandgap device. This means, for example, a tandem n-p DSSC with TiO2 and NiO porous electrodes will hardly work better than the champion single DSSC. A source code of the program used for calculations is also provided.

  13. Optimal design and loss mechanism analysis of microwave absorbing unidirectional SiC fiber composites with broad absorption band and good polarization stability

    NASA Astrophysics Data System (ADS)

    Wan, Guangchao; Jiang, Jianjun; He, Yun; Bie, Shaowei

    2016-04-01

    A microwave-absorbing unidirectional SiC fiber composite with wide absorption and good polarization stability was designed by genetic algorithm. The anisotropic nature of unidirectional fiber composites was considered in the design by characterizing tensor permittivity. This special composite is composed of two kinds of SiC fibers that separately exhibit relatively high conductivity and low conductivity. The electromagnetic loss mechanism of this composite was examined for polarizations that differ in the electric field of the incident wave, applied either in the direction of the fiber or in the transverse direction, perpendicular to the fibers. For both polarizations, the absorption band of our composite can reach 6 GHz and the lowest microwave reflectivity was about -20 dB over a range of 8-18 GHz. When the electric field is polarized parallel to fibers, strong coupling among the high-conductivity fibers can induce a strong current and thus efficiently dissipate the electromagnetic energy. When the electric field is polarized perpendicular to fibers, the electromagnetic loss mechanism in the composite resembles the electric energy loss in capacitors and currents in the transverse direction are obstructed by the fibers resulting in attenuation of the electromagnetic energy in the matrix.

  14. Highly ordered monolayer/bilayer TiO2 hollow sphere films with widely tunable visible-light reflection and absorption bands.

    PubMed

    Li, Jie; Qin, Yao; Jin, Chao; Li, Ying; Shi, Donglu; Schmidt-Mende, Lukas; Gan, Lihua; Yang, Jinhu

    2013-06-07

    Monolayer and bilayer TiO2 hollow hemisphere/sphere (THH/THS) films consisting of highly ordered hexagonal-patterned THHs/THSs with thin shells of ~10 nm and different diameters of ~170 and ~470 nm have been prepared by templating of two-dimensional polystyrene sphere (PS) assembly films coupled with TiO2 sputtering/wet coating approaches. Owing to their precisely adjustable structural parameters, such as THH/THS shape and diameter as well as film layer thickness, the prepared THH/THS films exhibit widely tunable visible-light reflection and absorption bands, i.e. from 380 to 850 nm for reflection and 390 to 520 nm for absorption, respectively. The mechanism of the novel optical behaviors of the THH/THS films has been discussed in depth, combined with some calculations according to Bragg's law. In addition, photocatalytic experiments of RhB degradation employing the THH/THS films as recyclable catalysts have been conducted. The THH/THS films with controlled structures and precisely tunable optical properties are attractive for a wide range of applications, such as recyclable catalysts for photocatalysis, efficient oxide electrodes or scattering layers for solar cells, gas-permeable electrode materials for high-performance sensors and so on.

  15. Iron-absorption band analysis for the discrimination of iron-rich zones. [infrared spectral reflectance of Nevada iron deposits

    NASA Technical Reports Server (NTRS)

    Rowan, L. C. (Principal Investigator)

    1974-01-01

    The author has identified the following significant results. Most major rock units and unaltered and altered areas in the study area can be discriminated on the basis of visible and near-infrared spectral reflectivity differences recorded from satellite altitude. These subtle spectral differences are detectable by digital ratioing of the MSS bands and subsequent stretching to increase the contrast to enhance spectral differences. Hydrothermally altered areas appear as anomalous color patches within the volcanic-rock areas. A map has been prepared which can be regarded as an excellent reconnaissance exploration map, for use in targeting areas for more detailed geological, geochemical, and geophysical studies. Mafic and felsic rock types are easily discriminated on the color stretched-ratio composite. The ratioing process minimizes albedo effects, leaving only the recorded characteristic spectral response. The spectra of unaltered rocks appear different from those of altered rocks, which are typically dominated by limonite and clay minerals. It seems clear that differences in spectral shape can provide a basis for discrimination of geologic material, although the relations between visible and near-infrared spectral reflectivity and mineralogical composition are not yet entirely understood.

  16. Electromagnetic properties and microwave absorption properties of BaTiO 3-carbonyl iron composite in S and C bands

    NASA Astrophysics Data System (ADS)

    Rui-gang, Yang

    2011-07-01

    BaTiO3 powders are prepared by sol-gel method. The carbonyl iron powder is prepared via thermal decomposition of iron pentacarbonyl. Then BaTiO3-carbonyl iron composite with different mixture ratios was prepared using the as-prepared material. The structure, morphology, and properties of the composites are characterized using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction, scanning electron microscopy (SEM), and a network analyzer. The complex permittivity and reflection loss of the composites have been measured at different microwave frequencies in S- and C-bands employing vector network analyzer model PNA 3629D vector. The effect of the mass ratio of BaTiO3/carbonyl iron on the microwave loss properties of the composites is investigated. A possible microwave absorbing mechanism of BaTiO3-carbonyl iron composite has been proposed. The BaTiO3-carbonyl iron composite can find applications in suppression of electromagnetic interference, and reduction of radar signature.

  17. Cavity Ringdown Absorption Spectrum of the T_1(n,π*) ← S_0 Transition of Acrolein: Analysis of the 0^0_0 Band Rotational Contour

    NASA Astrophysics Data System (ADS)

    Hlavacek, Nikolaus C.; McAnally, Michael O.; Drucker, Stephen

    2012-06-01

    Acrolein (propenal, CH_2=CH---CH=O) is the simplest conjugated enal molecule and serves as a prototype for investigating the photochemical properties of larger enals and enones. Acrolein has a coplanar arrangement of heavy atoms in its ground electronic state. Much of the photochemistry is mediated by the T_1(π,π*) state, which has a CH_2--twisted equilibrium structure. In solution, the T_1(π,π*) state is typically accessed via intersystem crossing from an intially prepared planar S_1(n,π*) state. An intermediate in this photophysical transformation is the lowest ^3 (n,π*) state, a planar species with adiabatic excitation energy below S_1 and above T_1(π,π*). The present work focuses on this ^3 (n,π*) intermediate state; it is designated T_1(n,π*) as the lowest-energy triplet state of acrolein having a planar equilibrium structure. The T_1(n,π*) ← S_0 band system, with origin near 412 nm, was first recorded in the 1970s at medium (0.5 cm-1) resolution using a long-path absorption cell. Here we report the cavity ringdown spectrum of the 0^0_0 band, recorded using a pulsed dye laser with 0.1 cm-1 spectral bandwidth. The spectrum was measured under both bulk-gas (room-temperature) and jet-cooled conditions. The band contour in each spectrum was analyzed by using a computer program developed for simulating and fitting the rotational structure of singlet-triplet transitions. The assignment of several resolved sub-band heads in the room-temperature spectrum permitted approximate fitting of the inertial constants for the T_1(n,π*) state. The determined values (cm-1) are A=1.662, B=0.1485, C=0.1363. For the parameters A and (B+C)/2, estimated uncertainties of ± 0.003 cm-1 and ± 0.0004 cm-1, respectively, correspond to a range of values that produce qualitatively satisfactory global agreement with the observed room-temperature contour. The fitted inertial constants were used to simulate the rotational contour of the 0^0_0 band under jet-cooled conditions

  18. Strain and temperature dependent absorption spectra studies for identifying the phase structure and band gap of EuTiO3 perovskite films.

    PubMed

    Jiang, Kai; Zhao, Run; Zhang, Peng; Deng, Qinglin; Zhang, Jinzhong; Li, Wenwu; Hu, Zhigao; Yang, Hao; Chu, Junhao

    2015-12-21

    Post-annealing has been approved to effectively relax the out-of-plane strain in thin films. Epitaxial EuTiO3 (ETO) thin films, with and without strain, have been fabricated on (001) LaAlO3 substrates by pulsed laser deposition. The absorption and electronic transitions of the ETO thin films are investigated by means of temperature dependent transmittance spectra. The antiferrodistortive phase transition can be found at about 260-280 K. The first-principles calculations indicate there are two interband electronic transitions in ETO films. Remarkably, the direct optical band gap and higher interband transition for ETO films show variation in trends with different strains and temperatures. The strain leads to a band gap shrinkage of about 240 meV while the higher interband transition an expansion of about 140 meV. The hardening of the interband transition energies in ETO films with increasing temperature can be attributed to the Fröhlich electron-phonon interaction. The behavior can be linked to the strain and low temperature modified valence electronic structure, which is associated with rotations of the TiO6 octahedra.

  19. The Janus faces of ESAs: caveat Chimaera!

    PubMed

    Penny, Hugo; Leckström, Daniel; Goldsmith, David

    2013-06-01

    Patients with chronic kidney disease (CKD) have a Janus quality as they look back whence they came in developing CKD and, in some cases, also look forwards to a potential kidney transplant with the attendant promise of improvement in quality and often quantity of life. Making the most of this often unique opportunity is key-maximising the chance that the engraftment starts as a success, and then later, preserving good kidney transplant function for as long as possible. Two recently published, independently conceived and executed studies are relevant to both aspects of this quest and thus to all kidney transplant recipients (KTRs). Both trials also simultaneously stoke and quench the continuing, heated debates over target haemoglobin (Hb) levels, and the use of erythropoiesis-stimulating agents (ESAs), in CKD patients. One study--of acute, high-dose ESA administration--adds to the plethora of adverse safety signals swirling around the use of ESAs while surprisingly also showing renal function benefits at 12 months. The other study features chronic lower-dose ESA use in stable KTRs with anaemia and impaired renal function and not only purports to show a salutary effect on 2-year renal function outcomes (and thus reducing "return to dialysis" rates), but also rebuts the now widely accepted current notion that by chronic use of ESAs to target full Hb correction/higher Hb values in anaemic CKD patients, we are potentially causing harm.

  20. ESA strategic planning for space exploration

    NASA Astrophysics Data System (ADS)

    Hufenbach, B.; Reiter, T.; Sourgens, E.

    2014-08-01

    The European Space Agency (ESA) is pursuing an independent strategic planning process for consolidating a destination driven (LEO, Moon, Mars) space exploration strategy. ESA's space exploration strategy is driven by the goals to maximise knowledge gain and to contribute to economic growth. International cooperation is a key pillar of ESA's strategy as it is considered both, an enabler for achieving common goals and a benefit, opening new perspective for addressing future challenges. The achievement of ESA's space exploration strategy is enabled through international partnerships. The interagency coordination process conducted within the framework of the International Space Exploration Coordination Group (ISECG) plays an important role in laying the foundations for future partnerships. It has achieved so far the development of a common vision for space exploration, a common plan for implementing the vision in the form of the Global Exploration Roadmap, as well as a common approach for articulating the value of global space exploration. ESA has been a strong promoter and supporter of the interagency coordination process conducted within ISECG and thanks to its unique expertise in international cooperation the Agency has contributed to its success.

  1. ESA personal communications and digital audio broadcasting systems based on non-geostationary satellites

    NASA Technical Reports Server (NTRS)

    Logalbo, P.; Benedicto, J.; Viola, R.

    1993-01-01

    Personal Communications and Digital Audio Broadcasting are two new services that the European Space Agency (ESA) is investigating for future European and Global Mobile Satellite systems. ESA is active in promoting these services in their various mission options including non-geostationary and geostationary satellite systems. A Medium Altitude Global Satellite System (MAGSS) for global personal communications at L and S-band, and a Multiregional Highly inclined Elliptical Orbit (M-HEO) system for multiregional digital audio broadcasting at L-band are described. Both systems are being investigated by ESA in the context of future programs, such as Archimedes, which are intended to demonstrate the new services and to develop the technology for future non-geostationary mobile communication and broadcasting satellites.

  2. Modelling of Collision Induced Absorption Spectra Of H2-H2 Pairs for the Planetary Atmospheres Structure: The Second Overtone Band

    NASA Technical Reports Server (NTRS)

    Borysow, Aleksandra; Borysow, Jacek I.

    1998-01-01

    The main objective of the proposal was to model the collision induced, second overtone band of gaseous hydrogen at low temperatures. The aim of this work is to assist planetary scientists in their investigation of planetary atmospheres, mainly those of Uranus and Neptune. The recently completed extended database of collision induced dipole moments of hydrogen pairs allowed us, for the first time, to obtain dipole moment matrix elements responsible for the roto-vibrational collision induced absorption spectra of H2-H2 in the second overtone band. Despite our numerous attempts to publish those data, the enormous volume of the database did not allow us to do this. Instead, we deposited the data on a www site. The final part of this work has been partially supported by NASA, Division for Planetary Atmospheres. In order to use our new data for modelling purpose, we first needed to test how well we can reproduce the existing experimental data from theory, when using our new input data. Two papers resulted from this work. The obtained agreement between theoretical results and the measurements appeared to be within 10-30%. The obviously poorer agreement than observed for the first H2 overtone, the fundamental, and the rototranslational bands can be attributed to the fact that dipole moments responsible for the second overtone are much weaker, therefore susceptible to larger numerical uncertainties. At the same time, the intensity of the second overtone band is much weaker and therefore it is much harder to be measured accurately in the laboratory. We need to point out that until now, no dependable model of the 2nd overtone band was available for modelling of the planetary atmospheres. The only one, often referred to in previous works on Uranian and Neptune's atmospheres, uses only one lineshape, with one (or two) parameter(s) deduced at the effective temperature of Uranus (by fitting the planetary observation). After that, the parameter(s) was(were) made temperature

  3. ESA's Earth Observation in Support of Geoscience

    NASA Astrophysics Data System (ADS)

    Liebig, Volker

    2016-04-01

    The intervention will present ESA's Earth Observation Programme and its contribution to Geoscience. ESA's Earth observation missions are mainly grouped into three categories: The Sentinel satellites in the context of the European Copernicus Programme, the scientific Earth Explorers and the meteorological missions. Developments, applications and scientific results for the different mission types will be addressed, along with overall trends and strategies. A special focus will be put on the Earth Explorers, who form the science and research element of ESA's Living Planet Programme and focus on the atmosphere, biosphere, hydrosphere, cryosphere and Earth's interior. In addition the operational Sentinel satellites have a huge potential for Geoscience. Earth Explorers' emphasis is also on learning more about the interactions between these components and the impact that human activity is having on natural Earth processes. The process of Earth Explorer mission selection has given the Earth science community an efficient tool for advancing the understanding of Earth as a system.

  4. The New ESA Planetary Science Archive

    NASA Astrophysics Data System (ADS)

    Barbarisi, I.; Rios, C.; Macfarlane, A. J.; Docasal, R.; Gonzalez, J.; Arviset, C.; De Marchi, G.; Martinez, S.; Grotheer, E.; Lim, T.; Besse, S.; Heather, D.; Fraga, D.; Barthelemy, M.

    2015-12-01

    The ESA's Planetary Science Archive (PSA) is the central repository for all scientific and engineering data returned by ESA's planetary missions, making them accessible to the world-wide scientific community.With the advent of new ESA planetary missions, currently in development Bepi Colombo (Mercury) and ExoMars16 (Mars), and later on ExoMars18 (Mars Rover) and JUICE (Jupiter and moons), the PSA faces the need of supporting new functionalities and requirements.Within this scenario there is a need for a new concept of the PSA, supporting both the evolution of the PDS standard (PDS4), and the growing need for better interfaces and advanced applications toward a better science exploitation. We introduce the new PSA layout, conceived for better data discovery and retrieval, with special emphasis on GIS technology, interoperability and visualization capabilities.

  5. The Gravitational Universe - ESA's L3 mission

    NASA Astrophysics Data System (ADS)

    Mueller, Guido; Ando, Masaki; Binetruy, Pierre; Bouyer, Philippe; Cacciapuoti, Luigi; Cruise, Mike; Favata, Fabio; Gehler, Martin; Genzel, Reinhard; Jennrich, Oliver; Kasevich, Mark; Klipstein, Bill; Perryman, Michael; Safa, Frederic; Schutz, Bernard; Stebbins, Robin; Vitale, Stefano

    2015-04-01

    Following the advice of ESA's Senior Survey Committee (SSC) the Science Programme Committee (SPC) decided in November 2013 to select the science theme ``The Gravitational Universe'' for their L3 mission. The Director of Science and Robotic Exploration (D/SRE) has established a Gravitational Observatory Advisory Team (GOAT) to advise on the scientific and technological approaches for a gravitational wave observatory with a planned launch date in 2034. Our team is comprised of scientists from Europe and the US as well as scientists and engineers from ESA and observers from NASA and JAXA. We meet about every ten weeks, evaluate the technical readiness of all necessary technologies, study the science impact of different mission designs, and will advise ESA on the required future technology development. We will report on our progress and plans forward to a future space-based gravitational-wave observatory. For JAXA.

  6. A search for formic acid in the upper troposphere - A tentative identification of the 1105-per cm nu-6 band Q branch in high-resolution balloon-borne solar absorption spectra

    NASA Technical Reports Server (NTRS)

    Goldman, A.; Murcray, F. H.; Murcray, D. G.; Rinsland, C. P.

    1984-01-01

    Infrared solar absorption spectra recorded at 0.02-per cm resolution during a balloon flight from Alamogordo, NM (33 deg N), on March 23, 1981, have been analyzed for the possible presence of absorption by formic acid (HCOOH). An absorption feature at 1105 per cm has been tentatively identified in upper tropospheric spectra as due to the nu-6 band Q branch. A preliminary analysis indicates a concentration of about 0.6 ppbv and 0.4 ppbv near 8 and 10 km, respectively.

  7. The ESA Scientific Exploitation of Operational Missions element

    NASA Astrophysics Data System (ADS)

    Desnos, Yves-Louis; Benveniste, Jerome; Delwart, Steven; Engdahl, Marcus; Regner, Peter; Zehner, Claus; Mathieu, Pierre Philippe; Arino, Olivier; Bojkov, Bojan; Ferran, Gaston; Donlon, Craig; Kern, Michael; Scipal, Klaus

    2013-04-01

    The prime objective of the ESA Scientific Exploitation of Operational Missions (SEOM) programme element is to federate, support and expand the large international research community that the ERS, ENVISAT and the Envelope programmes have built up over the last 20 years. It aims to further strengthen the international leadership of European Earth Observation research community by enabling them to extensively exploit observations from future European operational EO missions. SEOM will enable the science community to address many new avenues of scientific research that will be opened by free and open access to data from operational EO missions. As a preparation for the SEOM element a series of international science users consultation has been organized by ESA in 2012 covering Sentinel 1 (FRINGE /SEASAR ), Sentinel 2 ( S2 symposium), Sentinel 3 (COAST-ALT workshop , 20 Years Progress in Radar Altimetry, Sentinel 3 OLCI/SLSTR 2012 workshop) and Sentinel 4-5 (Atmospheric Science Confrence). The science users recommendations have been gathered and form the basis for the work plan 2013 for the SEOM element. The SEOM element is organized along the following action lines: 1. Developing, validating and maintaining open-source, multi-mission, scientific software toolboxes capable to handle the Sentinels data products 2. Stimulating the development and validation of advanced EO methods and observation strategies in particular the new TOpS mode on Sentinel 1, the new band settings on Sentinel 2, the new geometry/bands of Sentinel 3 OLCI ,SLSTR intruments and the advanced delay-doppler (SAR) altimeter exploitation. 3. Continuing to federate, support and expand the multi-disciplinary expert EO research communities by organizing thematic workshops and ensuring high-quality scientific publications linked to these research domains. Promoting widespread scientific use of data. 4. Training the next generation of European EO scientists on the scientific exploitation of Sentinel s data

  8. Cloud top height retrieval using the imaging polarimeter (3MI) top-of-atmosphere reflectance measurements in the oxygen absorption band

    NASA Astrophysics Data System (ADS)

    Kokhanovsky, Alexander; Munro, Rose

    2016-04-01

    The determination of cloud top height from a satellite has a number of applications both for climate studies and aviation safety. A great variety of methods are applied using both active and passive observation systems in the optical and microwave spectral regions. One of the most popular methods with good spatial coverage is based on the measurement of outgoing radiation in the spectral range where oxygen strongly absorbs incoming solar light. Clouds shield tropospheric oxygen reducing the depth of the corresponding absorption line as detected by a satellite instrument. Radiative transfer models are used to connect the solar light reflectance, e.g., in the oxygen A-band located around 761nm, and the cloud top height. The inverse problem is then solved e.g. using look-up tables, to determine the cloud top height. In this paper we propose a new fast and robust oxygen A-band method for the retrieval of cloud altitude using the Multi-viewing Multi-channel Multi-polarization Imaging instrument (3MI) on board the EUMETSAT Polar System Second Generation (EPS-SG). The 3MI measures the intensity at the wavelengths of 410, 443, 490, 555, 670, 763, 765, 865, 910, 1370, 1650, and 2130nm, and (for selected channels) the second and third Stokes vector components which allows the degree of linear polarization and the polarization orientation angle of reflected solar light to be derived at up to 14 observation angles. The instrument response function (to a first approximation) can be modelled by a Gaussian distribution with the full width at half maximum (FWHM) equal to 20nm for all channels except 765nm, 865nm, 1370nm, 1650nm, and 2130nm, where it is equal to 40nm. The FWHM at 763nm (the oxygen A-band location) is equal to 10nm. The following 3MI channels are used in the retrieval procedure: 670, 763, and 865nm. The channels at 670 and 865 nm are not affected by the oxygen absorption. The channel at 763nm is affected by the oxygen concentration vertical profile. The higher

  9. Resonance Raman intensity analysis of the excited state proton transfer dynamics of 2-nitrophenol in the charge-transfer band absorption

    SciTech Connect

    Wang Yaqiong; Wang Huigang; Zhang Shuqiang; Pei Kemei; Zheng Xuming; Lee Phillips, David

    2006-12-07

    Resonance Raman spectra were obtained for 2-nitrophenol in cyclohexane solution with excitation wavelengths in resonance with the charge-transfer (CT) proton transfer band absorption. These spectra indicate that the Franck-Condon region photodissociation dynamics have multidimensional character with motion along more than 15 normal modes: the nominal CCH bend+CC stretch {nu}{sub 12} (1326 cm{sup -1}), the nominal CCC bend {nu}{sub 23} (564 cm{sup -1}), the nominal CO stretch+NO stretch+CC stretch {nu}{sub 14} (1250 cm{sup -1}), the nominal CCH bend+CC stretch+COH bend {nu}{sub 15} (1190 cm{sup -1}); the nominal CCH bend+CC stretch {nu}{sub 17} (1134 cm{sup -1}), the nominal CCC bend+CC stretch {nu}{sub 22} (669 cm{sup -1}), the nominal CCN bend {nu}{sub 27} (290 cm{sup -1}), the nominal NO{sub 2} bend+CC stretch {nu}{sub 21} (820 cm{sup -1}), the nominal CCO bend+CNO bend {nu}{sub 25} (428 cm{sup -1}), the nominal CC stretch {nu}{sub 7} (1590 cm{sup -1}), the nominal NO stretch {nu}{sub 8} (1538 cm{sup -1}), the nominal CCC bend+NO{sub 2} bend {nu}{sub 20} (870 cm{sup -1}), the nominal CC stretch {nu}{sub 6} (1617 cm{sup -1}), the nominal COH bend+CC stretch {nu}{sub 11} (1382 cm{sup -1}), nominal CCH bend+CC stretch {nu}{sub 9} (1472 cm{sup -1}). A preliminary resonance Raman intensity analysis was done and the results for 2-nitrophenol were compared to previously reported results for nitrobenzene, p-nitroaniline, and 2-hydroxyacetophenone. The authors briefly discuss the differences and similarities in the CT-band absorption excitation of 2-nitrophenol relative to those of nitrobenzene, p-nitroaniline, and 2-hydroxyacetophenone.

  10. Application of surface pressure measurements of O2-band differential absorption radar system in three-dimensional data assimilation on hurricane: Part II - A quasi-observational study

    NASA Astrophysics Data System (ADS)

    Min, Qilong; Gong, Wei; Lin, Bing; Hu, Yongxiang

    2015-01-01

    This is the second part on assessing the impacts of assimilating various distributions of sea-level pressure (SLP) on hurricane simulations, using the Weather and Research Forecast (WRF) three dimensional variational data assimilation system (3DVAR). One key purpose of this series of study is to explore the potential of using remotely sensed sea surface barometric data from O2-band differential absorption radar system currently under development for server weather including hurricane forecasts. In this part II we further validate the conclusions of observational system simulation experiments (OSSEs) in the part I using observed SLP for three hurricanes that passed over the Florida peninsula. Three SLP patterns are tested again, including all available data near the Florida peninsula, and a band of observations either through the center or tangent to the hurricane position. Before the assimilation, a vortex SLP reconstruction technique is employed for the use of observed SLP as discussed in the part I. In agreement with the results from OSSEs, the performance of assimilating SLP is enhanced for the two hurricanes with stronger initial minimum SLP, leading to a significant improvement in the track and position relative to the control where no data are assimilated. On the other hand, however, the improvement in the hurricane intensity is generally limited to the first 24-48 h of integration, while a high resolution nested domain simulation, along with assimilation of SLP in the coarse domain, shows more profound improvement in the intensity. A diagnostic analysis of the potential vorticity suggests that the improved track forecasts are attributed to the combined effects of adjusting the steering wind fields in a consistent manner with having a deeper vortex, and the associated changes in the convective activity.

  11. Aerothermodynamics in Europe: ESA Achievements and Challenges

    NASA Astrophysics Data System (ADS)

    Muylaert, J.-M.

    2005-02-01

    Europe is faced with challenging aerothermodynamic problems for several of ESA's human space flight and exploration, science, application and launcher programmes. The Aerothermodynamic section at ESA/ESTEC provided technical support to these programmes and implemented research and development programmes to improve industrial tools for design in a way to strengthen the co-operation between universities, research establishments and industry. The ESA programmes involving Aerothermodynamics are: • Human space flight and exploration: CARV, PARES, IRDT, EXPERT, EVD, ATV, COLUMBUS • Science programmes : Huygens, MARS, VEX • Launcher programmes: ARIANE, VEGA, Future Launchers Preparatory Programme (FLPP). • Satellite telecommunication and earth observation programmes: MSG, EOLUS, CRYOSAT, GOCE • Technological Research programmes: improvements of the tools for design and analysis of space vehicles (ground-based facilities, flight test and measurement techniques and numerical/physical modelling validation activities) The paper will review past ESA aerothermodynamic activities by highlighting achievements obtained on the occasion of the past 4 Aerothermodynamics symposia. Critical aerothermodynamic issues for the design of reentry space vehicles and launchers will be addressed. A number of analysis and test results will be presented, the need for advanced numerical tools will be addressed and the importance of flight-testing will be identified for the validation of the methods and procedures for flight extrapolation of results obtained from ground-based facilities.

  12. The ESA Space Debris Mitigation Handbook 2002

    NASA Astrophysics Data System (ADS)

    Klinkrad, H.; Beltrami, P.; Hauptmann, S.; Martin, C.; Sdunnus, H.; Stokes, H.; Walker, R.; Wilkinson, J.

    2004-01-01

    The ESA Space Debris Mitigation Handbook 2002 was jointly produced by an industrial consortium and ESA, under an ESA contract. The Handbook is a non-regulatory, self-standing document, providing technical information in support of European debris mitigation standards. The necessity of debris mitigation is illustrated in the context of historic launch activities and operational practices, which led to the current debris environment, with corresponding collision flux levels. Based on detailed population evolution models, this initial population is analyzed with respect to its growth and stability under different traffic assumptions. The implementation of debris mitigation measures, in particular the de-orbiting of spacecraft and upper stages, is shown to reduce the debris growth to an acceptable level within a few decades. The risk on ground due to re-entering space objects, its assessment, and its control is also analyzed. For on-orbit systems, collision risk reduction by avoidance manoeuvres, and passive protection by shielding is outlined. ESA's Handbook also compares recommended debris mitigation and risk reduction practices proposed by several other space agencies. The Handbook will be available at the begin of 2003.

  13. The ESA Space Debris Mitigation Handbook 2002

    NASA Astrophysics Data System (ADS)

    Klinkrad, H.; Beltrami, P.; Hauptmann, S.; Martin, C.; Sdunnus, H.; Stokes, H.; Walker, R.; Wilkinson, J.

    The ESA Space Debris Mitigation Handbook 2002 was jointly produced by an industrial consortium and ESA, under an ESA contract. The Handbook is a non-regulatory, self-standing document, providing technical information in support of European debris mitigation standards. The necessity of debris mitigation is illustrated in the context of historic launch activities and operational practices, which led to the current debris environment, with corresponding collision flux levels. Based on detailed population evolution models, this initial population is analysed with respect to its growth and stability under different traffic assumptions. The implementation of debris mitigation measures, in particular the de-orbiting of spacecraft and upper stages, is shown to reduce the debris growth to an acceptable level within a few decades. The risk on ground due to re-entering space objects, its assessment, and its control is also analysed. For on-orbit systems, collision risk reduction by avoidance manoeuvres, and passive protection by shielding is outlined. ESA's Handbook also compares recommended debris mitigation and risk reduction practices proposed by several other space agencies. The Handbook will be available by the end of 2002.

  14. Modeling of collision-induced infrared absorption spectra of H2 pairs in the first overtone band at temperatures from 20 to 500 K

    NASA Technical Reports Server (NTRS)

    Zheng, Chunguang; Borysow, Aleksandra

    1995-01-01

    A simple formalism is presented that permits quick computations of the low-resolution, rotovibrational collision-induced absorption (RV CIA) spectra of H2 pairs in the first overtone band of hydrogen, at temperatures from 20 to 500 K. These spectra account for the free-free transitions. The sharp dimer features, originating from the bound-free, free-bound, and bound-bound transitions are ignored, though their integrated intensities are properly accounted for. The method employs spectral model line- shapes with parameters computed from the three lowest spectral moments. The moments are obtained from first principles expressed as analytical functions of temperature. Except for the sharp dimer features, which are absent in this model, the computed spectra reproduce closely the results of exact quantum mechanical lineshape computations. Comparisons of the computed spectra with existing experimental data also show good agreement. The work interest for the modeling of the atmospheres of the outer planets in the near-infrared region of the spectrum. The user-friendly Fortran program developed here is available on request from the authors.

  15. Inhomogeneous broadening and peak shift of the 7.6 eV optical absorption band of oxygen vacancies in SiO2

    NASA Astrophysics Data System (ADS)

    Kajihara, Koichi; Skuja, Linards; Hosono, Hideo

    2014-10-01

    The peak parameters of radiation-induced 7.6 eV optical absorption band of oxygen vacancies (Si-Si bonds) were examined for high-purity synthetic α-quartz and amorphous SiO2 (a-SiO2) exposed to 60Co γ-rays. The peak shape is asymmetric with the steeper edge at the lower energy side both in α-quartz and a-SiO2, and the peak energy is larger for α-quartz than that for a-SiO2. The full width at half maximum for a-SiO2 is larger by ˜40-60% than that for α-quartz, and it increases with an increase in the disorder of the a-SiO2 network, which is enhanced by raising the temperature of preannealing before irradiation, i.e., fictive temperature. These data are interpreted from the viewpoint of the site-to-site distribution of the Si-Si bond length in a-SiO2.

  16. Ti3C2 MXenes with Modified Surface for High-Performance Electromagnetic Absorption and Shielding in the X-Band.

    PubMed

    Han, Meikang; Yin, Xiaowei; Wu, Heng; Hou, Zexin; Song, Changqing; Li, Xinliang; Zhang, Litong; Cheng, Laifei

    2016-08-17

    Electromagnetic (EM) absorbing and shielding composites with tunable absorbing behaviors based on Ti3C2 MXenes are fabricated via HF etching and annealing treatment. Localized sandwich structure without sacrificing the original layered morphology is realized, which is responsible for the enhancement of EM absorbing capability in the X-band. The composite with 50 wt % annealed MXenes exhibits a minimum reflection loss of -48.4 dB at 11.6 GHz, because of the formation of TiO2 nanocrystals and amorphous carbon. Moreover, superior shielding effectiveness with high absorption effectiveness is achieved. The total and absorbing shielding effectiveness of Ti3C2 MXenes in a wax matrix with a thickness of only 1 mm reach values of 76.1 and 67.3 dB, while those of annealed Ti3C2 MXenes/wax composites are 32 and 24.2 dB, respectively. Considering the promising performance of Ti3C2 MXenes with the modified surface, this work is expected to open the door for the expanded applications of MXenes family in EM absorbing and shielding fields.

  17. Inhomogeneous broadening and peak shift of the 7.6 eV optical absorption band of oxygen vacancies in SiO{sub 2}

    SciTech Connect

    Kajihara, Koichi; Skuja, Linards; Hosono, Hideo

    2014-10-21

    The peak parameters of radiation-induced 7.6 eV optical absorption band of oxygen vacancies (Si-Si bonds) were examined for high-purity synthetic α-quartz and amorphous SiO{sub 2} (a‐SiO{sub 2}) exposed to {sup 60}Co γ-rays. The peak shape is asymmetric with the steeper edge at the lower energy side both in α-quartz and a‐SiO{sub 2}, and the peak energy is larger for α-quartz than that for a‐SiO{sub 2}. The full width at half maximum for a‐SiO{sub 2} is larger by ∼40-60% than that for α-quartz, and it increases with an increase in the disorder of the a‐SiO{sub 2} network, which is enhanced by raising the temperature of preannealing before irradiation, i.e., fictive temperature. These data are interpreted from the viewpoint of the site-to-site distribution of the Si-Si bond length in a‐SiO{sub 2}.

  18. Temperature dependence of the intensity of the vibration-rotational absorption band ν2 of H2O trapped in an argon matrix

    NASA Astrophysics Data System (ADS)

    Pitsevich, G.; Doroshenko, I.; Malevich, A..; Shalamberidze, E.; Sapeshko, V.; Pogorelov, V.; Pettersson, L. G. M.

    2017-02-01

    Using two sets of effective rotational constants for the ground (000) and the excited bending (010) vibrational states the calculation of frequencies and intensities of vibration-rotational transitions for J″ = 0 - 2; and J‧ = 0 - 3; was carried out in frame of the model of a rigid asymmetric top for temperatures from 0 to 40 K. The calculation of the intensities of vibration-rotational absorption bands of H2O in an Ar matrix was carried out both for thermodynamic equilibrium and for the case of non-equilibrium population of para- and ortho-states. For the analysis of possible interaction of vibration-rotational and translational motions of a water molecule in an Ar matrix by 3D Schrödinger equation solving using discrete variable representation (DVR) method, calculations of translational frequencies of H2O in a cage formed after one argon atom deleting were carried out. The results of theoretical calculations were compared to experimental data taken from literature.

  19. Proposal of high efficiency solar cells with closely stacked InAs/In{sub 0.48}Ga{sub 0.52}P quantum dot superlattices: Analysis of polarized absorption characteristics via intermediate–band

    SciTech Connect

    Yoshikawa, H. Kotani, T.; Kuzumoto, Y.; Izumi, M.; Tomomura, Y.; Hamaguchi, C.

    2014-07-07

    We present a theoretical study of the electronic structures and polarized absorption properties of quantum dot superlattices (QDSLs) using wide–gap matrix material, InAs/In{sub 0.48}Ga{sub 0.52}P QDSLs, for realizing intermediate–band solar cells (IBSCs) with two–step photon–absorption. The plane–wave expanded Burt–Foreman operator ordered 8–band k·p theory is used for this calculation, where strain effect and piezoelectric effect are taken into account. We find that the absorption spectra of the second transitions of two–step photon–absorption can be shifted to higher energy region by using In{sub 0.48}Ga{sub 0.52}P, which is lattice–matched material to GaAs substrate, as a matrix material instead of GaAs. We also find that the transverse magnetic polarized absorption spectra in InAs/In{sub 0.48}Ga{sub 0.52}P QDSL with a separate IB from the rest of the conduction minibands can be shifted to higher energy region by decreasing the QD height. As a result, the second transitions of two–step photon–absorption by the sunlight occur efficiently. These results indicate that InAs/In{sub 0.48}Ga{sub 0.52}P QDSLs are suitable material combination of IBSCs toward the realization of ultrahigh efficiency solar cells.

  20. Proposal of high efficiency solar cells with closely stacked InAs/In0.48Ga0.52P quantum dot superlattices: Analysis of polarized absorption characteristics via intermediate-band

    NASA Astrophysics Data System (ADS)

    Yoshikawa, H.; Kotani, T.; Kuzumoto, Y.; Izumi, M.; Tomomura, Y.; Hamaguchi, C.

    2014-07-01

    We present a theoretical study of the electronic structures and polarized absorption properties of quantum dot superlattices (QDSLs) using wide-gap matrix material, InAs/In0.48Ga0.52P QDSLs, for realizing intermediate-band solar cells (IBSCs) with two-step photon-absorption. The plane-wave expanded Burt-Foreman operator ordered 8-band k . p theory is used for this calculation, where strain effect and piezoelectric effect are taken into account. We find that the absorption spectra of the second transitions of two-step photon-absorption can be shifted to higher energy region by using In0.48Ga0.52P, which is lattice-matched material to GaAs substrate, as a matrix material instead of GaAs. We also find that the transverse magnetic polarized absorption spectra in InAs/In0.48Ga0.52P QDSL with a separate IB from the rest of the conduction minibands can be shifted to higher energy region by decreasing the QD height. As a result, the second transitions of two-step photon-absorption by the sunlight occur efficiently. These results indicate that InAs/In0.48Ga0.52P QDSLs are suitable material combination of IBSCs toward the realization of ultrahigh efficiency solar cells.

  1. ESA's planning and coordination of the OLYMPUS propagation experiment

    NASA Technical Reports Server (NTRS)

    Arbesser-Rastburg, B.

    1992-01-01

    An overview of the organization of the OLYMPUS propagation experimenters group (OPEX) is given. Preparations, participation, and experiments are described. Some examples for first statistical results are also reported. OLYMPUS, a 3-axis stabilized communications satellite was launched in 1989 for providing experimental telecommunications payloads and a propagation beacon payload at 12, 20, and 30 GHz to the European Space Agency. From previous experience (OTS), the Agency undertook to carry out extensive preparations with an eye on obtaining the statistical results needed within the limited available lifetime of the spacecraft. The OLYMPUS propagation experiment was conceived as part of ESA's space telecommunications applications program (ESA/IPC/(79)83) with the emphasis on exploring the possibilities and limitations of Ka-band satellite communications. The objectives of the OLYMPUS propagation campaign were: (1) characterization of the slant-path propagation conditions at 20/30 GHz in the various climatic regions of Europe; (2) improvement of the understanding of the link between atmospheric observable (rain rate, cloud thickness, etc.) to propagation impairments such as attenuation, depolarization, scintillation, etc.; and (3) arrive at improved propagation prediction methods.

  2. ESA'S Biomass Mission System And Payload Overview

    NASA Astrophysics Data System (ADS)

    Arcioni, M.; Bensi, P.; Fois, F.; Gabriele, A.; Heliere, F.; Lin, C. C.; Massotti, L.; Scipal, K.

    2013-12-01

    Earth Explorers are the backbone of the science and research element of ESA's Living Planet Programme, providing an important contribution to the understanding of the Earth system. Following the User Consultation Meeting held in Graz, Austria on 5-6 March 2013, the Earth Science Advisory Committee (ESAC) has recommended implementing Biomass as the 7th Earth Explorer Mission within the frame of the ESA Earth Observation Envelope Programme. This paper will give an overview of the satellite system and its payload. The system technical description presented here is based on the results of the work performed during parallel Phase A system studies by two industrial consortia led by EADS Astrium Ltd. and Thales Alenia Space Italy. Two implementation concepts (respectively A and B) are described and provide viable options capable of meeting the mission requirements.

  3. Electronic structure of an [FeFe] hydrogenase model complex in solution revealed by X-ray absorption spectroscopy using narrow-band emission detection.

    PubMed

    Leidel, Nils; Chernev, Petko; Havelius, Kajsa G V; Schwartz, Lennart; Ott, Sascha; Haumann, Michael

    2012-08-29

    High-resolution X-ray absorption spectroscopy with narrow-band X-ray emission detection, supported by density functional theory calculations (XAES-DFT), was used to study a model complex, ([Fe(2)(μ-adt)(CO)(4)(PMe(3))(2)] (1, adt = S-CH(2)-(NCH(2)Ph)-CH(2)-S), of the [FeFe] hydrogenase active site. For 1 in powder material (1(powder)), in MeCN solution (1'), and in its three protonated states (1H, 1Hy, 1HHy; H denotes protonation at the adt-N and Hy protonation of the Fe-Fe bond to form a bridging metal hydride), relations between the molecular structures and the electronic configurations were determined. EXAFS analysis and DFT geometry optimization suggested prevailing rotational isomers in MeCN, which were similar to the crystal structure or exhibited rotation of the (CO) ligands at Fe1 (1(CO), 1Hy(CO)) and in addition of the phenyl ring (1H(CO,Ph), 1HHy(CO,Ph)), leading to an elongated solvent-exposed Fe-Fe bond. Isomer formation, adt-N protonation, and hydride binding caused spectral changes of core-to-valence (pre-edge of the Fe K-shell absorption) and of valence-to-core (Kß(2,5) emission) electronic transitions, and of Kα RIXS data, which were quantitatively reproduced by DFT. The study reveals (1) the composition of molecular orbitals, for example, with dominant Fe-d character, showing variations in symmetry and apparent oxidation state at the two Fe ions and a drop in MO energies by ~1 eV upon each protonation step, (2) the HOMO-LUMO energy gaps, of ~2.3 eV for 1(powder) and ~2.0 eV for 1', and (3) the splitting between iron d(z(2)) and d(x(2)-y(2)) levels of ~0.5 eV for the nonhydride and ~0.9 eV for the hydride states. Good correlations of reduction potentials to LUMO energies and oxidation potentials to HOMO energies were obtained. Two routes of facilitated bridging hydride binding thereby are suggested, involving ligand rotation at Fe1 for 1Hy(CO) or adt-N protonation for 1HHy(CO,Ph). XAES-DFT thus enables verification of the effects of ligand

  4. Lunar Exploration and Science in ESA

    NASA Astrophysics Data System (ADS)

    Carpenter, James; Houdou, Bérengère; Fisackerly, Richard; De Rosa, Diego; Patti, Bernardo; Schiemann, Jens; Hufenbach, Bernhard; Foing, Bernard

    2015-04-01

    ESA seeks to provide Europe with access to the lunar surface, and allow Europeans to benefit from the opening up of this new frontier, as part of a global endeavor. This will be best achieved through an exploration programme which combines the strengths and capabilities of both robotic and human explorers. ESA is preparing for future participation in lunar exploration through a combination of human and robotic activities, in cooperation with international partners. Future planned activities include the contribution of key technological capabilities to the Russian led robotic missions, Luna-Glob, Luna-Resurs orbiter and Luna-Resurs lander. For the Luna-Resurs lander ESA will provide analytical capabilities to compliment the Russian led science payload, focusing on developing an characterising the resource opportunities offered at the lunar surface. This should be followed by the contributions at the level of mission elements to a Lunar Polar Sample Return mission. These robotic activities are being performed with a view to enabling a future more comprehensive programme in which robotic and human activities are integrated to provide the maximum benefits from lunar surface access. Activities on the ISS and ESA participation to the US led Multi-Purpose Crew Vehicle, which is planned for a first unmanned lunar flight in 2017, are also important steps towards achieving this. In the frame of a broader future international programme under discussion through the International Space Exploration Coordination Group (ISECG) future missions are under investigation that would provide access to the lunar surface through international cooperation and human-robotic partnerships.

  5. Lunar Exploration and Science in ESA

    NASA Astrophysics Data System (ADS)

    Carpenter, James; Houdou, Bérengère; Fisackerly, Richard; De Rosa, Diego; Patti, Bernardo; Schiemann, Jens; Hufenbach, Bernhard; Foing, Bernard

    2014-05-01

    ESA seeks to provide Europe with access to the lunar surface, and allow Europeans to benefit from the opening up of this new frontier, as part of a global endeavor. This will be best achieved through an exploration programme which combines the strengths and capabilities of both robotic and human explorers. ESA is preparing for future participation in lunar exploration through a combination of human and robotic activities, in cooperation with international partners. Future planned activities include the contribution of key technological capabilities to the Russian led robotic missions, Luna-Glob, Luna-Resurs orbiter and Luna-Resurs lander. For the Luna-Resurs lander ESA will provide analytical capabilities to compliment the already selected Russian led payload, focusing on the composition and isotopic abundances of lunar volatiles in polar regions. This should be followed by the contributions at the level of mission elements to a Lunar Polar Sample Return mission. This partnership will provide access for European investigators to the opportunities offered by the Russian led instruments on the missions, as well as providing Europe with a unique opportunity to characterize and utilize polar volatile populations. Ultimately samples of high scientific value, from as of yet unexplored and unsampled locations shall be made available to the scientific community. These robotic activities are being performed with a view to enabling a future more comprehensive programme in which robotic and human activities are integrated to provide the maximum benefits from lunar surface access. Activities on the ISS and ESA participation to the US led Multi-Purpose Crew Vehicle, which is planned for a first unmanned lunar flight in 2017, are also important steps towards achieving this. All of these activities are performed with a view to generating the technologies, capabilities, knowledge and heritage that will make Europe an indispensable partner in the exploration missions of the future.

  6. Lunar Exploration and Science in ESA

    NASA Astrophysics Data System (ADS)

    Carpenter, James; Foing, Bernard H.; Fisackerly, Richard; Houdou, Berengere; De Rosa, Diego; Patti, Bernado; Schiemann, Jens

    ESA seeks to provide Europe with access to the lunar surface, and allow Europeans to benefit from the opening up of this new frontier, as part of a global endeavor. This will be best achieved through an exploration programme which combines the strengths and capabilities of both robotic and human explorers. ESA is preparing for future participation in lunar exploration through a combination of human and robotic activities, in cooperation with international partners. Future planned activities include the contribution of key technological capabilities to the Russian led robotic missions, Luna-Glob, Luna-Resurs orbiter and Luna-Resurs lander. For the Luna-Resurs lander ESA will provide analytical capabilities to compliment the already selected Russian led payload, focusing on the abundance, composition and isotopes of lunar volatiles in polar regions, and their associated chemistry. This should be followed by the contributions at the level of mission elements to a Lunar Polar Sample Return mission. This partnership will provide access for European investigators to the opportunities offered by the Russian led instruments on the missions, as well as providing Europe with a unique opportunity to characterise and utilise polar volatile populations. Ultimately samples of high scientific value, from as of yet unexplored and unsampled locations shall be made available to the scientific community. These robotic activities are being performed with a view to enabling a future more comprehensive programme in which robotic and human activities are integrated to provide the maximum benefits from lunar surface access. Activities on the ISS and ESA participation to the US Multi-Purpose Crew Vehicle, which is planned for a first unmanned lunar flight in 2017, are also important steps towards achieving this. All of these activities are performed with a view to generating the technologies, capabilities, knowledge and heritage that will make Europe an indispensable partner in the

  7. Absorption intensity changes and frequency shifts of fundamental and first overtone bands for OH stretching vibration of methanol upon methanol-pyridine complex formation in CCl4: analysis by NIR/IR spectroscopy and DFT calculations.

    PubMed

    Futami, Yoshisuke; Ozaki, Yasushi; Ozaki, Yukihiro

    2016-02-21

    Infrared (IR) and near infrared (NIR) spectra were measured for methanol and the methanol-pyridine complex in carbon tetrachloride. Upon the formation of the methanol-pyridine complex, the frequencies of both the fundamental and first overtone bands of the OH stretching vibration shifted to lower frequencies, and the absorption intensity of the fundamental increased significantly, while that of the first overtone decreased markedly. By using quantum chemical calculations, we estimated the absorption intensities and frequencies of the fundamental and first overtone bands for the OH stretching vibration based on the one-dimensional Schrödinger equation. The calculated results well reproduced the experimental results. The molecular vibration potentials and dipole moment functions of the OH stretching vibration modes were compared between methanol and the methanol-pyridine complex in terms of absorption intensity changes and frequency shifts. The large change in the dipole moment function was found to be the main cause for the variations in absorption intensity for the fundamental and first overtone bands.

  8. Lunar Exploration and Science in ESA

    NASA Astrophysics Data System (ADS)

    Carpenter, J.; Houdou, B.; Fisackerly, R.; De Rosa, D.; Espinasse, S.; Hufenbach, B.

    2013-09-01

    Lunar exploration continues to be a priority for the European Space Agency (ESA) and is recognized as the next step for human exploration beyond low Earth orbit. The Moon is also recognized as an important scientific target providing vital information on the history of the inner solar system; Earth and the emergence of life, and fundamental information on the formation and evolution of terrestrial planets. The Moon also provides a platform that can be utilized for fundamental science and to prepare the way for exploration deeper into space and towards a human Mars mission, the ultimate exploration goal. Lunar missions can also provide a means of preparing for a Mars sample return mission, which is an important long term robotic milestone. ESA is preparing for future participation in lunar exploration through a combination of human and robotic activities, in cooperation with international partners. These include activities on the ISS and participation with US led Multi-Purpose Crew Vehicle, which is planned for a first unmanned lunar flight in 2017. Future activities planned activities also include participation in international robotic missions. These activities are performed with a view to generating the technologies, capabilities, knowledge and heritage that will make Europe an indispensible partner in the exploration missions of the future. We present ESA's plans for Lunar exploration and the current status of activities. In particular we will show that this programme gives rise to unique scientific opportunities and prepares scientifically and technologically for future exploratory steps.

  9. ESA Technologies for Space Debris Remediation

    NASA Astrophysics Data System (ADS)

    Wormnes, K.; Le Letty, R.; Summerer, L.; Schonenborg, R.; Dubois-Matra, O.; Luraschi, E.; Cropp, A.; Krag, H.; Delaval, J.

    2013-08-01

    Space debris is an existing and growing problem for space operations. Studies show that for a continued use of LEO, 5 - 10 large and strategically chosen debris need to be removed every year. The European Space Agency (ESA) is actively pursuing technologies and systems for space debris removal under its Clean Space initiative. This overview paper describes the activities that are currently ongoing at ESA and that have already been completed. Additionally it outlines the plan for the near future. The technologies under study fall in two main categories corresponding to whether a pushing or a pulling manoeuvre is required for the de-orbitation. ESA is studying the option of using a tethered capture system for controlled de-orbitation through pulling where the capture is performed using throw-nets or alternatively a harpoon. The Agency is also studying rigid capture systems with a particular emphasis on tentacles (potentially combined with a robotic arm). Here the de-orbitation is achieved through a push-manoeuvre. Additionally, a number of activities will be discussed that are ongoing to develop supporting technologies for these scenarios, or to develop systems for de-orbiting debris that can be allowed to re-enter in an uncontrolled manner. The short term goal and main driver for the current technology developments is to achieve sufficient TRL on required technologies to support a potential de-orbitation mission to remove a large and strategically chosen piece of debris.

  10. Absorption Bands at 4300 and 6000-8000Å as Signs of Silicate and Organic Matter Separation and Formation of Hydrated Silicates in KBOs and Similar Bodies

    NASA Astrophysics Data System (ADS)

    Busarev, V. V.; Dorofeeva, V. A.; Makalkin, A. B.

    2004-12-01

    Recent spectral observations of some Kuiper Belt Objects (KBOs) (Boehnhardt et al.: 2002, Proc. of ACM 2002, 47-50; Fornasier S. et al., 2004, Astron. Astrophys. 421, 353-363) discovered characteristic absorption bands at 4300 and 6000-8000Å in reflectance spectra of the bodies. Spectral positions and other parameters of the features are similar to those found in reflectance spectra of terrestrial phyllosilicates (e. g., Clark et al., 1990, J. Geophys. Res. 95, 12653-12680; Busarev et al., 2004, The new ROSETTA targets (L. Colangeli et al., eds.), 79-83), CI- and CM-carbonaceous chondrites (e. g., Busarev and Taran, 2002, Proc. of ACM 2002, 933-936), primitive C-, P-, D-, F- and G-class asteroids (Vilas and Gaffey, 1989, Science 246, 790-792) and hydrated M-, S- and E-class asteroids (Busarev and Taran, 2002, Proc. of ACM 2002, 933-936). Hence, these absorption bands may be considered as universal indicators of hydrated silicates on celestial solid bodies including KBOs. However, before phyllosilicates were formed, an aqueous media should spring up and exist a considerable time in the bodies. One more important factor for the spectral features of hydrated silicates to be observed, it is probably an aqueous separation of silicate and darkening CHON (PAH plus more light organic compounds) components in the bodies. To check the assumptions we have performed some calculations (Busarev et al., 2003, Earth, Moon, and Planets 92, 345-357) applicable to KBOs and analogous silicate-icy bodies existed for the first time in the formation zones of neighbouring giant planets. According to the calculations, the decay of the short-lived 26Al at the early stage of the bodies' evolution and their mutual collisions (at velocities >1.5 km s-1) at the subsequent stage were probably the main sources of heating sufficient for melting water ice in their interiors. Because of these processes, an internal ocean of liquid water covered with ˜10-km crust of dirty ice could originate in

  11. Screened coulomb hybrid DFT investigation of band gap and optical absorption predictions of CuVO3, CuNbO3 and Cu5Ta11O30 materials.

    PubMed

    Harb, Moussab; Masih, Dilshad; Takanabe, Kazuhiro

    2014-09-14

    We present a joint theoretical and experimental investigation of the optoelectronic properties of CuVO3, CuNbO3 and Cu5Ta11O30 materials for potential photocatalytic and solar cell applications. In addition to the experimental results obtained by powder X-ray diffraction and UV-Vis spectroscopy of the materials synthesized under flowing N2 gas at atmospheric pressure via solid-state reactions, the electronic structure and the UV-Vis optical absorption coefficient of these compounds are predicted with high accuracy using advanced first-principles quantum methods based on DFT (including the perturbation theory approach DFPT) within the screened coulomb hybrid HSE06 exchange-correlation formalism. The calculated density of states are found to be in agreement with the UV-Vis diffuse reflectance spectra, predicting a small indirect band gap of 1.4 eV for CuVO3, a direct band gap of 2.6 eV for CuNbO3, and an indirect (direct) band gap of 2.1 (2.6) eV for Cu5Ta11O30. It is confirmed that the Cu(I)-based multi-metal oxides possess a strong contribution of filled Cu(I) states in the valence band and of empty d(0) metal states in the conduction band. Interestingly, CuVO3 with its predicted small indirect band gap of 1.4 eV shows the highest absorption coefficient in the visible range with a broad absorption edge extending to 886 nm. This novel result offers a great opportunity for this material to be an excellent candidate for solar cell applications.

  12. The ESA's Space Trajectory Analysis software suite

    NASA Astrophysics Data System (ADS)

    Ortega, Guillermo

    The European Space Agency (ESA) initiated in 2005 an internal activity to develop an open source software suite involving university science departments and research institutions all over the world. This project is called the "Space Trajectory Analysis" or STA. This article describes the birth of STA and its present configuration. One of the STA aims is to promote the exchange of technical ideas, and raise knowledge and competence in the areas of applied mathematics, space engineering, and informatics at University level. Conceived as a research and education tool to support the analysis phase of a space mission, STA is able to visualize a wide range of space trajectories. These include among others ascent, re-entry, descent and landing trajectories, orbits around planets and moons, interplanetary trajectories, rendezvous trajectories, etc. The article explains that STA project is an original idea of the Technical Directorate of ESA. It was born in August 2005 to provide a framework in astrodynamics research at University level. As research and education software applicable to Academia, a number of Universities support this development by joining ESA in leading the development. ESA and Universities partnership are expressed in the STA Steering Board. Together with ESA, each University has a chair in the board whose tasks are develop, control, promote, maintain, and expand the software suite. The article describes that STA provides calculations in the fields of spacecraft tracking, attitude analysis, coverage and visibility analysis, orbit determination, position and velocity of solar system bodies, etc. STA implements the concept of "space scenario" composed of Solar system bodies, spacecraft, ground stations, pads, etc. It is able to propagate the orbit of a spacecraft where orbital propagators are included. STA is able to compute communication links between objects of a scenario (coverage, line of sight), and to represent the trajectory computations and

  13. The ESA Space Situational Awareness Preparatory Programme

    NASA Astrophysics Data System (ADS)

    Bobrinsky, Nicolas

    A new ESA Programme on Space Situational Awareness (SSA) has been approved during the ESA Council at Ministerial level in November 2008. A preparatory phase is in progress, covering the timeframe 2009 -2012. It concentrates on the architectural design of the SSA System, its governance and data policy, as well as on the provision of precursor services based on the federation of existing National and European assets. A continuation of the SSA programme will be proposed at the next Ministerial Council for the years 2012 and onwards. The SSA Preparatory Programme covers three distinct segments, namely: -Space Surveillance and Tracking of artificial objects orbiting the Earth -Space Weather -Near Earth Objects Each of the above segments has a strong relation with Science and is supported by specific RD Programmes at National, EC and ESA levels. In this paper, the scientific aspects of the three SSA Segments are outlined and the following main topics developed: • Space Surveillance: statistical models of the evolution of the space debris population in Earth-bound orbits, study of active mitigation measures, impact analysis, tracking and char-acterisation principles based on radar and optical techniques. • Space Weather: awareness of the natural space environment, detection and forecasting of space weather effects and interferences, analysis of appropriate ground and space-based sensors for the monitoring of the Sun, the solar wind, the radiation belts, the magnetosphere and the ionosphere. • Near Earth Objects (NEOs): methods for determination of physical characteristics of newly discovered objects, study of appropriate sensors based on radar and optical techniques, iden-tification and ranking of collision risks of NEOs with the Earth, study of possible mitigation measures (e.g. Don Quichotes project). The research topics undertaken during the preparatory programme, as well as those foreseen during the next phase, possibly with a strong international cooperation

  14. EL2 deep level defects and above-band gap two-photon absorption in high gain lateral semi-insulating GaAs photoconductive switch

    NASA Astrophysics Data System (ADS)

    Shi, Wei; Wang, Wei; Niu, Hongjian; Zhang, Xianbin; Ji, Weili

    2005-01-01

    Experiments of a lateral semi-insulating GaAs photoconductive switch, both linear and nonlinear mode of the switch were observed when the switch was triggered by 1064 nm laser pulses, with energy of 1.9 mJ and the pulse width of 60 ns, and operated at biased electric field of 4.37 kV/cm. It"s wavelength is longer than 876nm, but the experiments indicate that the semi-insulating GaAs photoconductive switches can absorb 1064 nm laser obviously, which is out of the absorption range of the GaAs material. It is not possible to explain this behavior by using intrinsic absorption mechanism. We think that there are two mostly kinds of absorption mechanisms play a key part in absorption process, they are the two-steps-single-photon absorption that based on the EL2 energy level and two-photon absorption.

  15. The ESA earth observation polar platform programme

    NASA Astrophysics Data System (ADS)

    Rast, M.; Readings, C. J.

    1991-08-01

    The overall scenario of ESA earth observation polar platform program is reviewed with particular attention given to instruments currently being considered for flight on the first European polar platforms. The major objectives of the mission include monitoring the earth's environment on various scales; management and monitoring of the earth's resources; improvement of the service provided to the worldwide operational meteorological community, investigation of the structure and dynamics of the earth's crust and interior. The program encompasses four main elements: an ERS-1 follow-on mission (ERS-2), a solid earth gravity mission (Aristoteles), a Meteosat Second Generation, and a series of polar orbit earth observation missions.

  16. Lunar Exploration and Science Opportunities in ESA

    NASA Astrophysics Data System (ADS)

    Carpenter, J.; Houdou, B.; Fisackerly, R.; De Rosa, D.; Schiemann, J.; Patti, B.; Foing, B.

    2014-04-01

    ESA seeks to provide Europe with access to the lunar surface, and allow Europeans to benefit from the opening up of this new frontier, as part of a global endeavour. This will be best achieved through an exploration programme which combines the strengths and capabilities of both robotic and human explorers. ESA is preparing for future participation in lunar exploration through a combination of human and robotic activities, in cooperation with international partners. Future planned activities include the contribution of key technological capabilities to the Russian led robotic missions, Luna-Glob, Luna-Resurs orbiter and Luna-Resurs lander. For the Luna-Resurs lander ESA will provide analytical capabilities to compliment the already selected Russian led payload, focusing on the composition and isotopic abundances of lunar volatiles in polar regions. This should be followed by the contributions at the level of mission elements to a Lunar Polar Sample Return mission. This partnership will provide access for European investigators to the opportunities offered by the Russian led instruments on the missions, as well as providing Europe with a unique opportunity to characterize and utilize polar volatile populations. Ultimately samples of high scientific value, from as of yet unexplored and unsampled locations shall be made available to the scientific community. These robotic activities are being performed with a view to enabling a future more comprehensive programme in which robotic and human activities are integrated to provide the maximum benefits from lunar surface access. Activities on the ISS and ESA participation to the US led Multi-Purpose Crew Vehicle, which is planned for a first unmanned lunar flight in 2017, are also important steps towards achieving this. All of these activities are performed with a view to generating the technologies, capabilities, knowledge and heritage that will make Europe an indispensible partner in the exploration missions of the future

  17. Lunar Exploration and Science in ESA

    NASA Astrophysics Data System (ADS)

    Carpenter, J.; Houdou, B.; Fisackerly, R.; De Rosa, D.; Patti, B.; Schiemann, J.; Hufenbach, B.; Foing, B.

    2014-04-01

    ESA seeks to provide Europe with access to the lunar surface, and allow Europeans to benefit from the opening up of this new frontier, as part of a global endeavor. This will be best achieved through an exploration programme which combines the strengths and capabilities of both robotic and human explorers. ESA is preparing for future participation in lunar exploration through a combination of human and robotic activities, in cooperation with international partners. Future planned activities include the contribution of key technological capabilities to the Russian led robotic missions, Luna-Glob, Luna-Resurs orbiter and Luna-Resurs lander. For the Luna-Resurs lander ESA will provide analytical capabilities to compliment the already selected Russian led payload, focusing on the composition and isotopic abundances of lunar volatiles in polar regions. This should be followed by the contributions at the level of mission elements to a Lunar Polar Sample Return mission. This partnership will provide access for European investigators to the opportunities offered by the Russian led instruments on the missions, as well as providing Europe with a unique opportunity to characterize and utilize polar volatile populations. Ultimately samples of high scientific value, from as of yet unexplored and unsampled locations shall be made available to the scientific community. These robotic activities are being performed with a view to enabling a future more comprehensive programme in which robotic and human activities are integrated to provide the maximum benefits from lunar surface access. Activities on the ISS and ESA participation to the US led Multi-Purpose Crew Vehicle, which is planned for a first unmanned lunar flight in 2017, are also important steps towards achieving this. All of these activities are performed with a view to generating the technologies, capabilities, knowledge and heritage that will make Europe an indispensible partner in the exploration missions of the future

  18. Second space Christmas for ESA: Huygens to begin its final journey to Titan/ Media activities.

    NASA Astrophysics Data System (ADS)

    2004-12-01

    your mail box! Messages from earthlings and pop music heading to Titan Before the mission was launched, ESA offered Europeans a unique opportunity to send a message to the unknown. Over 80 000 people wanted to share the excitement of this mission and wrote or drew a message that was engraved on a CD-ROM put on board the Huygens probe. The messages can be seen on http://television.esa.int/Huygens/index.cfm The same CD ROM carries four pop songs, composed by French musicians Julien Civange and Louis Haéri. More about this project at http://www.music2titan.com Specific information for media representatives going to ESA/ESOC Getting there: The nearest airport is Frankfurt-am-Main and it takes about 20 minutes by taxi to get to ESA/ESOC. A shuttle bus is also available from the airport approximately every 30 minutes. There are also frequent trains (approx. every 40 minutes) from the airport to Darmstadt (one change). http://www.heag.de/verkehr/02_02.html http://www.bahn.de/pv/view/index.shtml Accommodation: Darmstadt has many hotels, ranging in price from € 68 to € 230 (the closest to ESA/ESOC is a 4-star Maritim Konferenz Hotel, in walking distance from the Control Centre). For further information about Darmstadt hotels go to http://www.proregio-darmstadt.de/uebernachten/hotel.asp. If you need help with accommodation, do not hesitate to contact the ESA/ESOC travel office on +49(0)6151.902.885. Laptops/ Internet/ Cell Phones: Power supply rating: 220-240 volts (adaptor plug available in most hardware stores or at most international airport shops). Most North American cell phones will not work in Europe unless they are tri-band phones. Internet via LAN: Standard network connector RJ45 required in laptop. Internet via analogue modem: Standard RJ11 connector in laptop, special German Telekom TAE connection to the socket. Internet via ISDN: PCMCIA Card inside Laptop, RJ45 in the wall. The ESA/ESOC Press Rooms are equipped with ISDN and standard network with RJ45 cable. No

  19. ESA situational awareness of space weather

    NASA Astrophysics Data System (ADS)

    Luntama, Juha-Pekka; Glover, Alexi; Keil, Ralf; Kraft, Stefan; Lupi, Adriano

    2016-07-01

    ESA SSA Period 2 started at the beginning of 2013 and will last until the end of 2016. For the Space Weather Segment, transition to Period 2 introduced an increasing amount of development of new space weather service capability in addition to networking existing European assets. This transition was started already towards the end of SSA Period 1 with the initiation of the SSA Space Weather Segment architecture definition studies and activities enhancing existing space weather assets. The objective of Period 2 has been to initiate SWE space segment developments in the form of hosted payload missions and further expand the federated service network. A strong focus has been placed on demonstration and testing of European capabilities in the range of SWE service domains with a view to establishing core products which can form the basis of SWE service provision during SSA Period 3. This focus has been particularly addressed in the SSA Expert Service Centre (ESC) Definition and Development activity that was started in September 2015. This presentation will cover the current status of the SSA SWE Segment and the achievements during SSA Programme Periods 1 and 2. Particular attention is given to the federated approach that allow building the end user services on the best European expertise. The presentation will also outline the plans for the Space Weather capability development in the framework of the ESA SSA Programme in 2017-2020.

  20. The ESA Space Weather Applications Pilot Project

    NASA Astrophysics Data System (ADS)

    Glover, A.; Hilgers, A.; Daly, E.

    Following the completion in 2001 of two parallel studies to consider the feasibility of a European Space Weather Programme ESA embarked upon a space weather pilot study with the goal of prototyping European space weather services and assessing the overall market for such within Europe This pilot project centred on a number of targeted service development activities supported by a common infrastructure and making use of only existing space weather assets Each service activity included clear participation from at least one identified service user who was requested to provide initial requirements and regular feedback during the operational phase of the service These service activities are now reaching the end of their 2-year development and testing phase and are now accessible each with an element of the service in the public domain see http www esa-spaceweathet net swenet An additional crucial element of the study was the inclusion of a comprehensive and independent analysis of the benefits both economic and strategic of embarking on a programme which would include the deployment of an infrastructure with space-based elements The results of this study will be reported together with their implication for future coordinated European activities in this field

  1. ATLID, ESA Atmospheric LIDAR Developement Status

    NASA Astrophysics Data System (ADS)

    Pereira do Carmo, João; Hélière, Arnaud; Le Hors, L.; Toulemont, Y.; Lefebvre, A.

    2016-06-01

    The ATmospheric LIDAR ATLID[1] is part of the payload of the Earth Cloud and Aerosol Explorer[2] (EarthCARE) satellite mission, the sixth Earth Explorer Mission of the European Space Agency (ESA) Living Planet Programme. EarthCARE is a joint collaborative satellite mission conducted between ESA and the National Space Development Agency of Japan (JAXA) that delivers the Cloud Profiling Radar (CPR) instrument. The payload consists of four instruments on the same platform with the common goal to provide a picture of the 3D-dimensional spatial and the temporal structure of the radiative flux field at the top of atmosphere, within the atmosphere and at the Earth's surface. This paper is presenting an updated status of the development of the ATLID instrument and its subsystem design. The instrument has recently completed its detailed design, and most of its subsystems are already under manufacturing of their Flight Model (FM) parts and running specific qualification activities. Clouds and aerosols are currently one of the biggest uncertainties in our understanding of the atmospheric conditions that drive the climate system. A better modelling of the relationship between clouds, aerosols and radiation is therefore amongst the highest priorities in climate research and weather prediction.

  2. Future lunar exploration activities in ESA

    NASA Astrophysics Data System (ADS)

    Houdou, B.; Carpenter, J. D.; Fisackerly, R.; Koschny, D.; Pradier, A.; di Pippo, S.; Gardini, B.

    2009-04-01

    Introduction Recent years have seen a resurgence of interest in the Moon and various recent and coming orbital missions including Smart-1, Kaguya, Chandrayaan-1and Lunar Reconnaissance Orbiter are advancing our understanding. In 2004 the US announced a new Vision for Space Exploration [1], whose objectives are focused towards human missions to the Moon and Mars. The European Space Agency has established similar objectives for Europe, described in [2] and approved at the ESA ministerial council (2009). There is considerable potential for international cooperation in these activities, as formulated in the recently agreed Global Exploration Strategy [3]. Present lunar exploration activities at ESA emphasise the development of European technologies and capabilities, to enable European participation in future international human exploration of the Moon. A major element in this contribution has been identified as a large lunar cargo lander, which would fulfill an ATV-like function, providing logistical support to human activities on the Moon, extending the duration of sorties and the capabilities of human explorers. To meet this ultimate goal, ESA is currently considering various possible development approaches, involving lunar landers of different sizes. Lunar Lander Mission Options A high capacity cargo lander able to deliver consumables, equipment and small infrastructure, in both sortie and outpost mission scenarios, would use a full Ariane 5 launch and is foreseen in the 2020-2025 timeframe. ESA is also considering an intermediate, smaller-scale mission beforehand, to mature the necessary landing technologies, to demonstrate human-related capabilities in preparation of human presence on the Moon and in general to gain experience in landing and operating on the lunar surface. Within this frame, ESA is currently leading several feasibility studies of a small lunar lander mission, also called "MoonNEXT". This mission is foreseen to be to be launched from Kourou with a

  3. Experimental and theoretical study of absorption spectrum of the (CH3)2CO···HF complex. Influence of anharmonic interactions on the frequency and intensity of the C=O and H-F stretching bands.

    PubMed

    Bulychev, V P; Svishcheva, E A; Tokhadze, K G

    2014-01-03

    IR absorption spectra of mixtures (CH3)2CO/HF and free (CH3)2CO molecules are recorded in the region of 4000-900 cm(-1) with a Bruker IFS-125 HR vacuum Fourier spectrometer at room temperature with a resolution up to 0.02 cm(-1). Spectral characteristics of the 2ν(C=O) overtone band of free acetone are reliably measured. The ν1(HF) and ν(C=O) absorption bands of the (CH3)2CO···HF complex are obtained by subtracting the absorption bands of free HF and acetone and absorption lines of atmospheric water from the experimental spectrum of mixtures. The experimental data are compared with theoretical results obtained from variational solutions of 1D-4D vibrational Schrödinger equations. The anharmonic potential energy and dipole moment surfaces used in the calculations were computed in the MP2/6-311++G(2d,2p) approximation with corrections for the basis set superposition error. Comparison of the data derived from solutions for different combinations of vibrational degrees of freedom shows that taking the inter-mode anharmonic interactions into account has different effects on the transition frequencies and intensities. Particular attention has been given to elucidation of the influence of anharmonic coupling of the H-F and C=O stretches with the low-frequency intermolecular modes on their frequencies and intensities and the strength of resonance between the fundamental H-F and the first overtone C=O transitions.

  4. NASA/ESA CV-990 spacelab simulation

    NASA Technical Reports Server (NTRS)

    1975-01-01

    Due to interest in the application of simplified techniques used to conduct airborne science missions at NASA's Ames Research Center, a joint NASA/ESA endeavor was established to conduct an extensive Spacelab simulation using the NASA CV-990 airborne laboratory. The scientific payload was selected to perform studies in upper atmospheric physics and infrared astronomy with principal investigators from France, the Netherlands, England, and several groups from the United States. Communication links between the 'Spacelab' and a ground based mission operations center were limited consistent with Spacelab plans. The mission was successful and provided extensive data relevant to Spacelab objectives on overall management of a complex international payload; experiment preparation, testing, and integration; training for proxy operation in space; data handling; multiexperimenter use of common experimenter facilities (telescopes); multiexperiment operation by experiment operators; selection criteria for Spacelab experiment operators; and schedule requirements to prepare for such a Spacelab mission.

  5. ESA's Planetary Science Archive: Status and Plans

    NASA Astrophysics Data System (ADS)

    Heather, David; Barthelemy, Maud; Manaud, Nicolas; Martinez, Santa; Szumlas, Marek; Vazquez, Jose Luis; Arviset, Christophe; Osuna, Pedro; PSA Development Team

    2013-04-01

    Scientific and engineering data from ESA's planetary missions are made accessible to the world-wide scientific community via the Planetary Science Archive (PSA). The PSA consists of online services incorporating search, preview, download, notification and delivery basket functionality. The PSA currently holds data from Mars Express, Venus Express, SMART-1, Huygens, Rosetta and Giotto, as well as several ground-based cometary observations. It will be used for archiving on ExoMars, BepiColombo and for the European contributions to Chandrayaan-1. The focus of the PSA activities is on the long-term preservation of data and knowledge from ESA's planetary missions. Scientific users can access the data online using several interfaces: - The Advanced Search Interface allows complex parameter based queries, providing the end user with a facility to complete very specific searches on meta-data and geometrical parameters. - The Map-based Interface is currently operational only for Mars Express HRSC and OMEGA data. This interface allows an end-user to specify a region-of-interest by dragging a box onto a base map of Mars. From this interface, it is possible to directly visualize query results. The Map-based and Advanced interfaces are linked and cross-compatible. If a user defines a region-of-interest in the Map-based interface, the results can be refined by entering more detailed search parameters in the Advanced interface. - The FTP Browser Interface is designed for more experienced users, and allows for direct browsing and access of the data set content through ftp-tree search. Each dataset contains documentation and calibration information in addition to the scientific or engineering data. All PSA data are prepared by the corresponding instrument teams, and are made to comply with the internationally recognized PDS standards. PSA supports the instrument teams in the full archiving process, from the definition of the data products, meta-data and product labels through to

  6. Aspects of ESA s public outreach programme

    NASA Astrophysics Data System (ADS)

    Maree, H.

    The Science Programme Communication Service is currently implementing a new policy to increase the overall public interest in ESA Science Programme by adopting new ways of promoting its activities, accordingly to the simple principle that "different target audiences have different needs". It is clear that the general public (i.e. "the man in the street" / "the average tax- payer") rarely has the knowledge and the background to understand what exactly a space mission is, what it does and why it does it ("Mission oriented approach"). The experience has shown that a space mission becomes "popular" amongst this target audience when the relevant communication is done by passing generic/bas ic/simple messages ("Thematic oriented approach"). The careful selection of adequate supports together with efficient distribution and promotion networks are also key parameters for success of the latter approach. One should also note that the overall objective of this new policy, is to raise people's interest in space in general. By presenting the information under the ESA brand, the public will start more and more to associate this brand and Europe to space exploration. Within the next twelve months, four scientific missions will be launched. Interestingly, tree of them (SMART-1, ROSETTA and MARS EXPRESS) offer a unique opportunity to implement the new communication policy under the single thematic : Europe is exploring the Solar System. Nevertheless, the study of the various mission profiles and their potential communication impact lead us to choose to reach out the general public primarily via the sub-thematic : Europe goes to Mars.

  7. ESA unveils Spanish antenna for unique space mission

    NASA Astrophysics Data System (ADS)

    2000-05-01

    The newly refurbished antenna, which is located at the Villafranca del Castillo Satellite Tracking Station site (VILSPA) near Madrid, has been selected as the prime communication link with the Cluster II spacecraft. The VIL-1 antenna will play a vital role in ESA's Cluster mission by monitoring and controlling the four spacecraft and by receiving the vast amounts of data that will be returned to Earth during two years of operations. Scheduled for launch in summer 2000, the Cluster quartet will complete the most detailed investigation ever made into the interaction between our pl0anet's magnetosphere - the region of space dominated by Earth's magnetic field - and the continuous stream of charged particles emitted by the Sun - the solar wind. This exciting venture is now well under way, following completion of the satellite assembly and test programme and two successful verification flights by the newly developed Soyuz-Fregat launch vehicle. The ESA Flight Acceptance Review Board has accordingly given the go-ahead for final launch preparations at the Baikonur Cosmodrome in Kazakhstan. VILSPA, ESA and Cluster II Built in 1975, after an international agreement between the European Space Agency and the Spanish government, VILSPA is part of the European Space Operations Centre (ESOC) Tracking Station Network (ESTRACK). In the last 25 years, VILSPA has supported many ESA and international satellite programmes, including the International Ultraviolet Explorer (IUE), EXOSAT and the Infrared Space Observatory (ISO). In addition to supporting the Cluster II mission, it has been designated as the Science Operations Centre for ESA's XMM Newton mission and for the Far-Infrared Space Telescope (FIRST), which is due to launch in 2007. There are now more than half a dozen large dish antennae installed at VILSPA. One of these is the VIL-1 antenna, a 15 metre diameter dish which operates in the S-band radio frequency (1.8 - 2.7 GHz). This antenna has been modernised recently in order

  8. NASA's Preparations for ESA's L3 Gravitational Wave Mission

    NASA Astrophysics Data System (ADS)

    Stebbins, Robin

    2016-03-01

    The European Space Agency (ESA) selected gravitational-wave astrophysics as the science theme for its third large mission opportunity, known as `L3,' under its Cosmic Vision Programme. NASA is seeking a role as an international partner in L3. NASA is: (1) participating in ESA's early mission activities, (2) developing potential US technology contributions, (3) participating in ESA's LISA Pathfinder mission, (4) and conducting a study of how NASA might participate. This talk will survey the status of these activities.

  9. Status of ESA's EarthCARE mission, passive instruments payload

    NASA Astrophysics Data System (ADS)

    Wallace, Kotska; Hélière, Arnaud; Lefebvre, Alain; Eisinger, Michael; Wehr, Tobias

    2016-09-01

    EarthCARE is ESA's third Earth Explorer Core Mission, with JAXA providing one instrument. The mission allows unique data product synergies to improve understanding of atmospheric cloud-aerosol interactions and Earth's radiation balance. Retrieved data will be used to improve climate and numerical weather prediction models. EarthCARE accommodates two active instruments: an ATmospheric LIDar (ATLID) and a Cloud Profiling Radar (CPR), and two passive instruments: a Multi Spectral Imager (MSI) and a BroadBand Radiometer (BBR). The instruments will provide simultaneous, collocated imagery, allowing both individual and common data products. The active instruments provide data on microscopic levels, measured through the atmospheric depth. 3-D models of the atmospheric interactions are constructed from the data, which can be used to calculate radiation balance. The large footprint of the MSI provides contextual information for the smaller footprints of the active instruments. Data from the BBR allows the loop to be closed by providing a macroscopic measurement of the radiation balance. This paper will describe the passive instruments development status. MSI is a compact instrument with a 150 km swath providing 500 m pixel data in seven channels, whose retrieved data will give context to the active instrument measurements, as well as providing cloud and aerosol information. BBR measures reflected solar and emitted thermal radiation from the scene. To reduce uncertainty in the radiance to flux conversion, three independent view angles are observed for each scene. The combined data allows more accurate flux calculations, which can be further improved using MSI data.

  10. The Dark UNiverse Explorer (DUNE): proposal to ESA's cosmic vision

    NASA Astrophysics Data System (ADS)

    Refregier, A.

    2009-03-01

    The Dark UNiverse Explorer (DUNE) is a wide-field space imager whose primary goal is the study of dark energy and dark matter with unprecedented precision. For this purpose, DUNE is optimised for the measurement of weak gravitational lensing but will also provide complementary measurements of baryonic accoustic oscillations, cluster counts and the Integrated Sachs Wolfe effect. Immediate auxiliary goals concern the evolution of galaxies, to be studied with unequalled statistical power, the detailed structure of the Milky Way and nearby galaxies, and the demographics of Earth-mass planets. DUNE is an Medium-class mission which makes use of readily available components, heritage from other missions, and synergy with ground based facilities to minimise cost and risks. The payload consists of a 1.2 m telescope with a combined visible/NIR field-of-view of 1 deg2. DUNE will carry out an all-sky survey, ranging from 550 to 1600 nm, in one visible and three NIR bands which will form a unique legacy for astronomy. DUNE will yield major advances in a broad range of fields in astrophysics including fundamental cosmology, galaxy evolution, and extrasolar planet search. DUNE was recently selected by ESA as one of the mission concepts to be studied in its Cosmic Vision programme.

  11. The two-photon absorptivity of rotational transitions in the A2 Sigma hyperon + (v prime = O) - X-2 pion (v prime prime = O) gamma band of nitric oxide

    NASA Technical Reports Server (NTRS)

    Gross, K. P.; Mckenzie, R. L.

    1982-01-01

    A predominantly single-mode pulsed dye laser system giving a well characterized spatial and temporal output suitable for absolute two-photon absorptivity measurements was used to study the NO gamma(0,0) S11 + R21 (J double prime = 7-1/2) transition. Using a calibrated induced-fluorescence technique, an absorptivity parameter of 2.8 + or - 1.4 x 10 to the minus 51st power cm to the 6th power was obtained. Relative strengths of other rotational transitions in the gamma(0,0) band were also measured and shown to compare well with predicted values in all cases except the O12 (J double prime = 10-1/2) transition.

  12. Radar sounder performances for ESA JUICE mission

    NASA Astrophysics Data System (ADS)

    Berquin, Y. P.; Kofman, W. W.; Heggy, E.; Hérique, A.

    2012-12-01

    The Jupiter Icy moons Explorer (JUICE) is the first Large-class mission chosen as part of ESA's Cosmic Vision 2015-2025 program. The mission will study Jovian icy moons Ganymede and Europa as potential habitats for life, addressing two key themes of Cosmic Vision namely the conditions for planet formation and the emergence of life, and the Solar System interactions. The radar sounder instrument on this mission will have great potential to address specific science questions such as the presence of subsurface liquid water and ice shell geophysical structures. One major constraint for radar sounding is the roughness of the planetary surface. The work presented will focus on the characterization of Ganymede's surface topography to better understand its surface properties from a radar point of view. These results should help to put constraints on the design of JUICE's radar sounder. We use topographic data derived from the Voyager and Galileo missions images to try to characterize the surface structure and to quantify its geometry (in terms of slopes and RMS heights mainly). This study will help us evaluating the radar budget in a statistical approach. In addition, deterministic simulations of surface radar echoes conducted on synthetic surfaces -extrapolated from Digital Elevation Models- will be presented to better assess radar sounding performances.

  13. APEX - the Hyperspectral ESA Airborne Prism Experiment

    PubMed Central

    Itten, Klaus I.; Dell'Endice, Francesco; Hueni, Andreas; Kneubühler, Mathias; Schläpfer, Daniel; Odermatt, Daniel; Seidel, Felix; Huber, Silvia; Schopfer, Jürg; Kellenberger, Tobias; Bühler, Yves; D'Odorico, Petra; Nieke, Jens; Alberti, Edoardo; Meuleman, Koen

    2008-01-01

    The airborne ESA-APEX (Airborne Prism Experiment) hyperspectral mission simulator is described with its distinct specifications to provide high quality remote sensing data. The concept of an automatic calibration, performed in the Calibration Home Base (CHB) by using the Control Test Master (CTM), the In-Flight Calibration facility (IFC), quality flagging (QF) and specific processing in a dedicated Processing and Archiving Facility (PAF), and vicarious calibration experiments are presented. A preview on major applications and the corresponding development efforts to provide scientific data products up to level 2/3 to the user is presented for limnology, vegetation, aerosols, general classification routines and rapid mapping tasks. BRDF (Bidirectional Reflectance Distribution Function) issues are discussed and the spectral database SPECCHIO (Spectral Input/Output) introduced. The optical performance as well as the dedicated software utilities make APEX a state-of-the-art hyperspectral sensor, capable of (a) satisfying the needs of several research communities and (b) helping the understanding of the Earth's complex mechanisms. PMID:27873868

  14. Indirect optical absorption and origin of the emission from β-FeSi2 nanoparticles: Bound exciton (0.809 eV) and band to acceptor impurity (0.795 eV) transitions

    NASA Astrophysics Data System (ADS)

    Lang, R.; Amaral, L.; Meneses, E. A.

    2010-05-01

    We investigated the optical absorption of the fundamental band edge and the origin of the emission from β-FeSi2 nanoparticles synthesized by ion-beam-induced epitaxial crystallization of Fe+ implanted SiO2/Si(100) followed by thermal annealing. From micro-Raman scattering and transmission electron microscopy measurements it was possible to attest the formation of strained β-FeSi2 nanoparticles and its structural quality. The optical absorption near the fundamental gap edge of β-FeSi2 nanoparticles evaluated by spectroscopic ellipsometry showed a step structure characteristic of an indirect fundamental gap material. Photoluminescence spectroscopy measurements at each synthesis stage revealed complex emissions in the 0.7-0.9 eV spectral region, with different intensities and morphologies strongly dependent on thermal treatment temperature. Spectral deconvolution into four transition lines at 0.795, 0.809, 0.851, and 0.873 eV was performed. We concluded that the emission at 0.795 eV may be related to a radiative direct transition from the direct conduction band to an acceptor level and that the emission at 0.809 eV derives from a recombination of an indirect bound exciton to this acceptor level of β-FeSi2. Emissions 0.851 and 0.873 eV were confirmed to be typical dislocation-related photoluminescence centers in Si. From the energy balance we determined the fundamental indirect and direct band gap energies to be 0.856 and 0.867 eV, respectively. An illustrative energy band diagram derived from a proposed model to explain the possible transition processes involved is presented.

  15. ESA's Hipparcos finds rebels with a cause

    NASA Astrophysics Data System (ADS)

    2004-10-01

    hi-res Size hi-res: 20Kb Credits: S. Kerroudj, B. Famaey & A. Jorissen (Université Libre de Bruxelles) Artist's impression of the Milky Way Artist's impression of our galaxy, the Milky Way, an aggregate of thousands of millions of stars. The spiral arms are clearly visible. They are regions of enhanced density of stars and gas. The Sun is located near the edge of one arm, about half-way from the galactic centre. Spiral arms can impart a kick on stars orbiting close to them. These stars are then forced unto streams running inwards or outwards, whereas the bulk of stars in the Milky Way move in circular orbits around the galactic centre. Using data from ESA’s Hipparcos satellite, astronomers have now identified three such streams, reaching into the solar neighbourhood. High-resolution version (TIFF) Low-resolution version (JPG) The Sun and most stars near it follow an orderly, almost circular orbit around the centre of our galaxy, the Milky Way. Using data from ESA's Hipparcos satellite, a team of European astronomers has now discovered several groups of 'rebel' stars that move in peculiar directions, mostly towards the galactic centre or away from it, running like the spokes of a wheel. These rebels account for about 20% of the stars within 1000 light-years of the Sun, itself located about 25 000 light-years away from the centre of the Milky Way. The data show that rebels in the same group have little to do with each other. They have different ages so, according to scientists, they cannot have formed at the same time nor in the same place. Instead, they must have been forced together. "They resemble casual travel companions more than family members," said Dr Benoit Famaey, Université Libre de Bruxelles, Belgium. Famaey and his colleagues believe that the cause forcing the rebel stars together on their unusual trajectory is a 'kick' received from one of the Milky Way's spiral arms. The spiral arms are not solid structures but rather regions of higher density of

  16. Electronic transitions and heterogeneity of the bacteriophytochrome Pr absorption band: An angle balanced polarization resolved femtosecond VIS pump-IR probe study.

    PubMed

    Linke, Martin; Yang, Yang; Zienicke, Benjamin; Hammam, Mostafa A S; von Haimberger, Theodore; Zacarias, Angelica; Inomata, Katsuhiko; Lamparter, Tilman; Heyne, Karsten

    2013-10-15

    Photoisomerization of biliverdin (BV) chromophore triggers the photoresponse in native Agp1 bacteriophytochrome. We discuss heterogeneity in phytochrome Pr form to account for the shape of the absorption profile. We investigated different regions of the absorption profile by angle balanced polarization resolved femtosecond VIS pump-IR probe spectroscopy. We studied the Pr form of Agp1 with its natural chromophore and with a sterically locked 18Et-BV (locked Agp1). We followed the dynamics and orientations of the carbonyl stretching vibrations of ring D and ring A in their ground and electronically excited states. Photoisomerization of ring D is reflected by strong signals of the ring D carbonyl vibration. In contrast, orientational data on ring A show no rotation of ring A upon photoexcitation. Orientational data allow excluding a ZZZasa geometry and corroborates a nontwisted ZZZssa geometry of the chromophore. We found no proof for heterogeneity but identified a new, to our knowledge, electronic transition in the absorption profile at 644 nm (S0→S2). Excitation of the S0→S2 transition will introduce a more complex photodynamics compared with S0→S1 transition. Our approach provides fundamental information on disentanglement of absorption profiles, identification of chromophore structures, and determination of molecular groups involved in the photoisomerization process of photoreceptors.

  17. ESA activities in the use of microwaves for the remote sensing of the Earth

    NASA Technical Reports Server (NTRS)

    Maccoll, D.

    1984-01-01

    The program of activities under way in the European Space Agency (ESA) directed towards Remote Sensing of the oceans and troposphere is discussed. The initial project is the launch of a satellite named ERS-1 with a primary payload of microwave values in theee C- and Ku-bands. This payload is discussed in depth. The secondary payload includes precision location experiments and an instrument to measure sea surface temperature, which are described. The important topic of calibration is extensively discussed, and a review of activities directed towards improvements to the instruments for future satellites is presented. Some discussion of the impact of the instrument payload on the spacecraft design follows and the commitment of ESA to the provision of a service of value to the ultimate user is emphasized.

  18. From ESAS to Ares: A Chronology

    NASA Technical Reports Server (NTRS)

    Cook, Stephen A.

    2007-01-01

    Throughout my career, I have observed many launch vehicle efforts come and go. Although it may appear on the surface that those were dead-end streets, the knowledge we gained through them actually informs the work in progress. Following the tragic loss of the Space Shuttle Columbia's crew, the administration took the Columbia Accident Investigation Board's findings to heart and united the Agency behind the Vision for Space Exploration, with clear goals and objectives, including fielding a new generation of safe, reliable, and affordable space transportation. The genesis of the Ares I Crew Launch Vehicle and Ares V Cargo Launch Vehicle activities now under way by a nationwide Government and industry team was the confirmation of the current NASA Administrator in April 2005. Shortly thereafter, he commissioned a team of aerospace experts to conduct the Exploration Systems Architecture Study (ESAS), which gave shape to launch vehicles that will empower America's resurgence in scientific discovery through human and robotic space exploration. In October 2005, I was asked to lead this effort, building the team and forming the partnerships that will, in turn, build America's next human-rated space transportation system. In November 2006, the Ares I team began conducting the System Requirements Review milestone, just 1 year after its formation. We are gaining momentum toward the first test flight of the integrated vehicle system in 2009, just a few short years away. The Agency is now poised to deliver on the commitment this nation has made to advance our interests in space. In its inaugural year, the Ares team has conducted the first human-rated launch vehicle major milestone in over 30 years. Using the Exploration Systems Architecture Study recommendations as a starting point, the vehicle designs have been evolved to best meet customer and stakeholder requirements to fulfill the strategic goals outlined in the Vision for Space Exploration.

  19. ARIEL: an ESA M4 mission candidate

    NASA Astrophysics Data System (ADS)

    Puig, L.; Pilbratt, G. L.; Heske, A.; Escudero Sanz, I.; Crouzet, P.-E.

    2016-07-01

    The Atmospheric Remote sensing Infrared Exoplanet Large survey (ARIEL) mission is an M-class mission candidate within the science program Cosmic Vision of the European Space Agency (ESA). It was selected in June 2015 as one of three candidates to enter an assessment phase (phase 0/A). This process involves the definition of science and mission requirements as well as a preliminary model payload, and an internal Concurrent Design Facility (CDF) study providing the input to parallel industrial studies (in progress since 2016). After this process, the three candidates will be reviewed and in mid-2017 one of them will be selected as the M4 mission for launch in 2026. ARIEL is a survey-type mission dedicated to the characterisation of exoplanetary atmospheres. Using the differential technique of transit spectroscopy, ARIEL will obtain transmission and/or emission spectra of the atmospheres of a large and diverse sample of known exoplanets (~500) covering a wide range of masses, densities, equilibrium temperatures, orbital properties and host-star characteristics. This will include hot Jupiters to warm Super-Earths, orbiting M5 to F0 stars. This paper describes critical requirements, and reports on the results of the Concurrent Design Facility (CDF) study that was conducted in June / July 2015, providing a description of the resulting spacecraft design. It will employ a 0.7 m x 1.1 m off-axis three mirror telescope, feeding four photometric channels in the VNIR range (0.5-1.95 μm) and an IR spectrometer covering 1.95-7.8 μm.

  20. "Cosmic Vision": the new ESA Science Programme

    NASA Astrophysics Data System (ADS)

    2002-05-01

    The outcome of the ESA Council at Ministerial level held in Edinburgh in November 2001 was not as positive as expected for the Agency's Science Programme. It appeared that the money made available would not be sufficient to carry out the Long Term Programme approved by the Science Programme Committee in October 2000, based on financial assumptions approved by the same Committee in Bern in May 1999. The resources granted in Edinburgh taken at their face value meant the cancellation of a mission (e.g. GAIA). At the conclusion of the exercise, following extensive consultations with all its partners, the Executive could propose a revised plan, which not only maintained the missions approved in October 2000, but added the Eddington mission in addition. The new plan, strongly endorsed by the Science Programme Committee on the occasion of its 99th meeting, contains the following missions, listed by production groups: Astrophysics Group 1: XMM-Newton (1999), INTEGRAL (2002). X and Gamma Ray Observatories (studying the 'violent' universe) Group 2: Herschel, exploring the infrared and microwave universe; Planck, to study the cosmic microwave background; Eddington, searching for extra-solar planets and studying the stellar seismology. (The three missions will be launched in the 2007-2008 timeframe.) Group 3: GAIA, the ultimate galaxy mapper (to be launched no later than 2012). Missions will follow in the same group after 2012. Solar System Science: Group 1:Rosetta, a trip to a comet (2003); Mars Express, a Mars orbiter carrying the Beagle2 lander (2003); (Venus Express, a Venus orbiter, would have been in this group.) Group 2: SMART-1, which will demonstrate solar propulsion technology while on its way to the Moon (2003); BepiColombo, a mission to Mercury, Solar Orbiter, a mission to take a closer look at the Sun (missions to be launched in 2011-2012). Fundamental Physics missions: (one group only) STEP (2005) the 'equivalence principle' test, SMART2, a technology

  1. ESA unveils its big XMM spacecraft

    NASA Astrophysics Data System (ADS)

    1998-02-01

    have to imagine the big tube of XMM filled with focused X-rays en route to the detectors », says Robert Lainé, ESA's project manager for XMM. « That is the whole purpose of the mission, and our chief preoccupation has been with the three multi-mirror modules that accomplish it. Critics thought we were too ambitious, trying to nest 58 precisely formed mirrors together in each module. No one had ever attempted such a feat before. It was not easy, but thanks to excellent innovative work by European industry, XMM's telescopes are even better than we hoped ». X-rays are focused by glancing them off a carefully shaped mirror, like a bucket without a bottom. In a single-mirror telescope, most of the incoming X-rays miss the mirror. To catch more of them, designers nest multiple mirrors inside one another. Before XMM, astronomers had to choose between many mirrors with relatively poor focusing, or a very few mirrors with a sharp focus. With 58 precision-made mirrors in each of its three X-ray telescopes, XMM combines enormous gathering power with accurate focusing. Carl Zeiss in Germany made shaped and polished mandrels (moulds) for mirrors of 58 different diameters, up to 70 cm for the widest. Media Lario in Italy made the mirrors by electrodeposition of nickel on the mandrels, coated their inner surfaces with gold, and carefully assembled them in their nested configuration, in a framework fabricated by APCO in Switzerland. The performance of each XMM mirror module has been verified in special facilities of the Centre Spatial de Liège in Belgium and the Max-Planck Institut für extraterrestriche Physik in Germany. The first flight model conformed with the specification, and the second and third were even better. Some facts about XMM The total surface area of the extremely thin mirror that gathers X-rays in XMM's three multi-mirror telescopes (taken together) is larger than 200 m2. Two of the three X-ray telescopes are fitted with reflection grating spectrometers for the

  2. Atmospheric absorption cell characterization

    NASA Astrophysics Data System (ADS)

    1982-06-01

    The measurement capability of the Avionics Laboratory IR Facility was used to evaluate an absorption cell that will be used to simulate atmospheric absorption over horizontal paths of 1 - 10 km in length. Band models were used to characterize the transmittance of carbon dioxide (CO2), nitrogen (N2), and nitrous oxide (N2O) in the cell. The measured transmittance was compared to the calculated values. Nitrous oxide is important in the 4 - 4.5 micron range in shaping the weak line absorption of carbon dioxide. The absorption cell is adequate for simulating atmospheric absorption over these paths.

  3. On the state of the emitter of the 3.3 micron unidentified infrared band - Absorption spectroscopy of polycyclic aromatic hydrocarbon species

    NASA Technical Reports Server (NTRS)

    Flickinger, Gregory C.; Wdowiak, Thomas J.; Gomez, Percy L.

    1991-01-01

    Results of absorption measurements indicate that the PAH species responsible for the UIR (unidentified infrared) emission probably exist in a condensed form rather than as isolated molecules. It is shown that the peak absorption of the C-H stretch feature of vapor-phase PAHs occurs at a higher frequency than that of the condensed-phase PAHs and does not match the 3.289-micron interstellar feature. The vapor-phase experiments duplicate the phenomenon of the 3.3-micron profile simplification of PAH in KBr at elevated temperature. This confirms that the change of the profile with temperature is an intrinsic molecular effect, and is not a consequence of matrix (KBr) or condensed state interactions.

  4. ESA's Integral satellite ready for lift-off from Baikonur

    NASA Astrophysics Data System (ADS)

    2002-10-01

    ESA's INTEGRAL (International Gamma Ray Astrophysics Laboratory) satellite, will be launched by a Proton launcher from Baikonur, Kazakhstan on 17 October at 06:41 CEST (Central European Summer Time). The most sensitive gamma-ray observatory ever launched, INTEGRAL is a truly international mission involving all ESA member states plus the USA and Russia. It carries four instruments from teams led by scientists in Italy, France, Germany, Denmark and Spain to gather and analyse gamma-rays, X-rays and visible light from celestial objects. INTEGRAL will give astronomers across the world their clearest views yet of the most extreme environments in the Universe. It will detect radiation from the most violent events far away and from processes that made the Universe inhabitable. Media representatives in Europe can follow the videotransmission of the launch at ESA/Darmstadt (ESOC) in Germany, which will be acting as the main European press centre, ESA/Noordwijk (ESTEC) in the Netherlands, ESA/Frascati (ESRIN) in Italy or ESA/Villafranca (VILSPA) in Spain. At each site ESA specialists will be available for interviews. Media representatives wishing to attend are requested to complete the attached reply form and fax it to the Communication Office at the establishment of their choice. The ESA TV Service will provide video news releases and live coverage of the launch between 06:15-07:00 and 08:00-08:30 CEST. Details of the transmission schedule for the various Video News Releases can be found on http://television.esa.int The launch can also be followed live on the internet at www.esa.int/integrallaunch starting at 06:15 hrs.

  5. Band engineering of amorphous silicon ruthenium thin film and its near-infrared absorption enhancement combined with nano-holes pattern on back surface of silicon substrate

    NASA Astrophysics Data System (ADS)

    Guo, Anran; Zhong, Hao; Li, Wei; Gu, Deen; Jiang, Xiangdong; Jiang, Yadong

    2016-10-01

    Silicon is widely used in semiconductor industry but has poor performance in near-infrared photoelectronic devices because of its bandgap limit. In this study, a narrow bandgap silicon rich semiconductor is achieved by introducing ruthenium (Ru) into amorphous silicon (a-Si) to form amorphous silicon ruthenium (a-Si1-xRux) thin films through co-sputtering. The increase of Ru concentration leads to an enhancement of light absorption and a narrower bandgap. Meanwhile, a specific light trapping technique is employed to realize high absorption of a-Si1-xRux thin film in a finite thickness to avoid unnecessary carrier recombination. A double-layer absorber comprising of a-Si1-xRux thin film and silicon random nano-holes layer is formed on the back surface of silicon substrates, and significantly improves near-infrared absorption while the leaky light intensity is less than 5%. This novel absorber, combining narrow bandgap thin film with light trapping structure, may have a potential application in near-infrared photoelectronic devices.

  6. Application of surface pressure measurements from O2-band differential absorption radar system in three-dimensional data assimilation on hurricane: Part I - An observing system simulation experiments study

    NASA Astrophysics Data System (ADS)

    Min, Qilong; Gong, Wei; Lin, Bing; Hu, Yongxiang

    2015-01-01

    Sea level pressure (SLP) is an important variable in regulating hurricane motion. However, SLP generally cannot be measured in open oceans due to limited buoys. Because of the potential availability of an O2-band differential absorption radar for sea surface barometry, we investigate the value of assimilating various patterns of SLP from such a system on hurricane prediction using the Weather Research and Forecasting (WRF) three-dimensional variational data assimilation system (3DVAR) based on Observing System Simulation Experiments (OSSEs). An important objective of this series of study is to explore the potential to use space and airborne sea surface air pressure measurements from an O2-band differential absorption radar currently under development for server weather including hurricane forecasts. The surface pressure patterns include an area of SLP, and a band of SLP either through the center or tangent to the hurricane position; the latter two distributions are similar to what could be obtained from the differential absorption radar system, which could be installed on spaceborne satellites and/or mounted on reconnaissance aircraft. In the banded pressure cases, we propose a vortex reconstruction technique based on surface pressure field. Assimilating observations from the reconstructed surface pressure leads to a better representation of initial SLP and vertical cross-section of wind, relative to the control where no data is assimilated and to the assimilation without vortex reconstruction. In eight of the nine OSSEs simulations on three hurricanes with three leading times of integration, which cover a wide range of initial minimum SLP from 951 to 1011 hPa, substantial improvements are found not only in the hurricane track and position, but also in the hurricane intensity, in terms of the SLP and maximum surface wind. The only case without significant improvement is resulted from the very weak initial condition (SLP 1011 hPa), which had no clear indication of

  7. Relation of molecular structure to Franck-Condon bands in the visible-light absorption spectra of symmetric cationic cyanine dyes.

    PubMed

    Lin, Katrina Tao Hua; Silzel, John W

    2015-05-05

    A Franck-Condon (FC) model is used to study the solution-phase absorbance spectra of a series of seven symmetric cyanine dyes having between 22 and 77 atoms. Electronic transition energies were obtained from routine visible-light absorbance and fluorescence emission spectra. Harmonic normal modes were computed using density functional theory (DFT) and a polarizable continuum solvent model (PCM), with frequencies corrected using measured mid-infrared spectra. The model predicts the relative energies of the two major vibronic bands to within 5% and 11%, respectively, and also reproduces structure-specific differences in vibronic band shapes. The bands themselves result from excitation of two distinct subsets of normal modes, one with frequencies between 150 and 625cm(-1), and the other between 850 and 1480cm(-1). Vibronic transitions excite symmetric in-plane bending of the polymethine chain, in-plane bends of the polymethine and aromatic C-H bonds, torsions and deformations of N-alkyl substituents, and in the case of the indocyanines, in-plane deformations of the indole rings. For two dyes, the model predicts vibronic coupling into symmetry-breaking torsions associated with trans-cis photoisomerization.

  8. Excited-state absorption of Tm3 + -doped single crystals at photon-avalanche wavelengths

    NASA Astrophysics Data System (ADS)

    Garnier, N.; Moncorgé, R.; Manaa, H.; Descroix, E.; Laporte, P.; Guyot, Y.

    1996-04-01

    Excited-state absorption (ESA) spectra calibrated in units of cross sections are reported in the case of Tm3+-doped YAG, YAP, and Y2O3 single crystals around wavelengths at which photon-avalanche absorptions were observed recently. The peak ESA cross sections are compared with those obtained theoretically by using the Judd-Ofelt approach.

  9. Cirrus cloud optical and microphysical property retrievals from eMAS during SEAC4RS using bi-spectral reflectance measurements within the 1.88 µm water vapor absorption band

    NASA Astrophysics Data System (ADS)

    Meyer, Kerry; Platnick, Steven; Arnold, G. Thomas; Holz, Robert E.; Veglio, Paolo; Yorks, John; Wang, Chenxi

    2016-04-01

    Previous bi-spectral imager retrievals of cloud optical thickness (COT) and effective particle radius (CER) based on the Nakajima and King (1990) approach, such as those of the operational MODIS cloud optical property retrieval product (MOD06), have typically paired a non-absorbing visible or near-infrared wavelength, sensitive to COT, with an absorbing shortwave or mid-wave infrared wavelength sensitive to CER. However, in practice it is only necessary to select two spectral channels that exhibit a strong contrast in cloud particle absorption. Here it is shown, using eMAS observations obtained during NASA's SEAC4RS field campaign, that selecting two absorbing wavelength channels within the broader 1.88 µm water vapor absorption band, namely the 1.83 and 1.93 µm channels that have sufficient differences in ice crystal single scattering albedo, can yield COT and CER retrievals for thin to moderately thick single-layer cirrus that are reasonably consistent with other solar and IR imager-based and lidar-based retrievals. A distinct advantage of this channel selection for cirrus cloud retrievals is that the below-cloud water vapor absorption minimizes the surface contribution to measured cloudy top-of-atmosphere reflectance, in particular compared to the solar window channels used in heritage retrievals such as MOD06. This reduces retrieval uncertainty resulting from errors in the surface reflectance assumption and reduces the frequency of retrieval failures for thin cirrus clouds.

  10. Modeling of collision-induced infrared absorption spectra of H2-H2 pairs in the fundamental band at temperatures from 20 to 300 K. [Planetary atmospheres

    SciTech Connect

    Borysow, A. )

    1991-08-01

    The 20-300 K free-free rotovibrational collision-induced absorption (RV CIA) spectra of H2-H2 pairs are presently obtained by a numerical method which, in addition to closely matching known CIA spectra of H2-H2, can reproduce the results of the quantum-mechanical computations to within a few percent. Since the spectral lineshape parameters are derivable by these means from the lowest three quantum-mechanical spectral moments, these outer-planet atmosphere-pertinent model spectra may be computed on even small computers. 35 refs.

  11. Aerosol Climate Time Series Evaluation In ESA Aerosol_cci

    NASA Astrophysics Data System (ADS)

    Popp, T.; de Leeuw, G.; Pinnock, S.

    2015-12-01

    Within the ESA Climate Change Initiative (CCI) Aerosol_cci (2010 - 2017) conducts intensive work to improve algorithms for the retrieval of aerosol information from European sensors. By the end of 2015 full mission time series of 2 GCOS-required aerosol parameters are completely validated and released: Aerosol Optical Depth (AOD) from dual view ATSR-2 / AATSR radiometers (3 algorithms, 1995 - 2012), and stratospheric extinction profiles from star occultation GOMOS spectrometer (2002 - 2012). Additionally, a 35-year multi-sensor time series of the qualitative Absorbing Aerosol Index (AAI) together with sensitivity information and an AAI model simulator is available. Complementary aerosol properties requested by GCOS are in a "round robin" phase, where various algorithms are inter-compared: fine mode AOD, mineral dust AOD (from the thermal IASI spectrometer), absorption information and aerosol layer height. As a quasi-reference for validation in few selected regions with sparse ground-based observations the multi-pixel GRASP algorithm for the POLDER instrument is used. Validation of first dataset versions (vs. AERONET, MAN) and inter-comparison to other satellite datasets (MODIS, MISR, SeaWIFS) proved the high quality of the available datasets comparable to other satellite retrievals and revealed needs for algorithm improvement (for example for higher AOD values) which were taken into account for a reprocessing. The datasets contain pixel level uncertainty estimates which are also validated. The paper will summarize and discuss the results of major reprocessing and validation conducted in 2015. The focus will be on the ATSR, GOMOS and IASI datasets. Pixel level uncertainties validation will be summarized and discussed including unknown components and their potential usefulness and limitations. Opportunities for time series extension with successor instruments of the Sentinel family will be described and the complementarity of the different satellite aerosol products

  12. Follow the Mars Express launch from one of ESA's establishments

    NASA Astrophysics Data System (ADS)

    2003-05-01

    Europe’s first mission to the Red Planet will reach its target in December, after a six-month journey. Mars Express will help scientists answer questions about the Martian landscape, atmosphere and the origin of life that remain open, although a wealth of information is already available. Media representatives in Europe can follow the launch and initial orbital operations at ESA/Darmstadt (ESOC) in Germany, which will be acting as the main European press centre, or ESA/Noordwijk (ESTEC) in the Netherlands. ESA/Frascati (ESRIN) in Italy and the Italian Space Agency, ASI, are organising a joint event at the University of Rome. ESA/Villafranca (VILSPA) and the CDTI, the Spanish institution in charge of space issues, are organising a joint event in Spain at the Museo Principe Felipe de la Ciudad de las Artes y las Ciencias in Valencia. At each site ESA specialists will be available for interviews. Media representatives wishing to attend are requested to complete the attached reply form and fax it to the Communication Office at the establishment of their choice. The ESA TV Service will provide live televised coverage of the launch and initial orbital operations with English commentary, between 19:15 and 22:00 CEST. Satellite: Astra 2C at 19 degrees East Reception frequency: 10832 MHz Polarisation: Horizontal Symbol rate: 22 Msymb/s FEC: 5/6 Service ID: 61950 Service name: ESA TXT: none Details of the transmission schedule and satellite details for the various pre-launch Video News Releases can be found on http://television.esa.int. The launch can also be followed live on the internet at www.esa.int/marsexpresslaunch starting at 19:15 hrs. Here you can also find the launch diary, news, press releases, videos, images and more.

  13. ESA's SMART-1 satellite ready for lift-off

    NASA Astrophysics Data System (ADS)

    2003-09-01

    During the night of Saturday 27/Sunday 28 September, ESA’s SMART-1 satellite will be launched by an Ariane 5 rocket from Europe’s spaceport at Kourou at 20:02 hrs local time (01:02 hrs Central European Summer Time, 23:02 hrs GMT). SMART-1 is the first of a series of ‘Small Missions for Advanced Research in Technology’ designed to test key technologies for future spacecraft. It is Europe’s first mission to the Moon. Among the new technologies to be tested is the solar-electric propulsion which will power the spacecraft to its target. SMART-1 will help solve such questions as how the Moon came into being and whether there is water there. Media representatives in Europe can follow the launch and initial orbital operations at ESA/Darmstadt (ESOC) in Germany, which will be acting as the main European press centre, ESA/Noordwijk (ESTEC) in the Netherlands or ESA/Frascati (ESRIN) in Italy. At each site ESA specialists will be available for interviews. Media representatives wishing to attend are asked to complete the attached reply form and fax it to the Communication Office at the establishment of their choice. The ESA TV Service will provide live televised coverage of the launch and initial orbital operations with English commentary, between 00:40 and 02:00 CEST. Satellite: Astra 2C at 19 degrees East Transponder 57, horizontal, MPEG-2, MCPC Reception frequency: 10832 MHz Polarisation: Horizontal Symbol rate: 22000 MS/sec FEC: 5/6 Service name: ESA Details of the transmission schedule and the various pre-launch Video News Releases can be found on http://television.esa.int. On the ESA SMART-1 special website at: http://www.esa.int/smart1 you can also find news, press releases, videos, images and more about the mission.

  14. ESA to launch six scientific satellites

    NASA Astrophysics Data System (ADS)

    1995-09-01

    ship to Europe's spaceport in Kourou, French Guiana. Since then, all the satellite subsystems and scientific instruments have been thoroughly tested and found to be in order. ISO is now waiting its turn to be mated with the Ariane 44P launcher. The launch campaign will resume in early October for a launch on 3 November. Preparations for flight operations by ESA's space operation centre, ESOC in Darmstadt, Germany and the flight control centre at Villafranca, near Madrid, Spain are also in the final stages. Most of the work in the last two months before a launch involves training and performing simulations to prove flight readiness. The scientific community is eagerly awaiting the preliminary results of ISO's first look into space in November. SOHO SOHO arrived at Kennedy Space Centre on 1 August. It was given a welcome by hurricane ERIN, which forced an immediate transfer to its reserved NASA facility just after its transport plane had safely landed. Spacecraft preparation for launch has started with a thorough check of all the systems and instruments onboard SOHO and will proceed with an end-to-end test with the NASA control station at Goddard Spaceflight Centre. Parallel activities are proceeding in Europe on the final testing and inspection of the four reaction wheels which the spacecraft control system uses to keep all its instruments pointed very precisely at the sun. At the end of its preparation, the spacecraft will be mated to its Atlas IIAS launcher, which is due to lift off in the first week of December. CLUSTER All four Cluster spacecraft, together with all ancillary equipment, have now arrived at Europe's spaceport in Kourou, French Guiana. The spacecraft have been set up for final electrical testing in the Final Assembly Building , a new Ariane 5 facility. Major milestones in the campaign are the start of spacecraft fuelling operations at the beginning of November and the start of integration of the spacecraft with the launch vehicle in mid- December. The

  15. mkESA: enhanced suffix array construction tool.

    PubMed

    Homann, Robert; Fleer, David; Giegerich, Robert; Rehmsmeier, Marc

    2009-04-15

    We introduce the tool mkESA, an open source program for constructing enhanced suffix arrays (ESAs), striving for low memory consumption, yet high practical speed. mkESA is a user-friendly program written in portable C99, based on a parallelized version of the Deep-Shallow suffix array construction algorithm, which is known for its high speed and small memory usage. The tool handles large FASTA files with multiple sequences, and computes suffix arrays and various additional tables, such as the LCP table (longest common prefix) or the inverse suffix array, from given sequence data.

  16. Status of esa smart-1 mission to the moon

    NASA Astrophysics Data System (ADS)

    Foing, B. H.; Racca, G. R.; Marini, A.; SMART-1 Technology Working Team

    2003-04-01

    SMART-1 is the first in the programme of ESA’s Small Missions for Advanced Research and Technology . Its objective is to demonstrate Solar Electric Primary Propulsion (SEP) for future Cornerstones (such as Bepi-Colombo) and to test new technologies for spacecraft and instruments. The spacecraft has been readied for launch in spring 2003 as an Ariane-5 auxiliary passenger. After a cruise with primary SEP, the SMART-1 mission is to orbit the Moon for a nominal period of six months, with possible extension. The spacecraft will carry out a complete programme of scientific observations during the cruise and in lunar orbit. SMART-1's science payload, with a total mass of some 19 kg, features many innovative instruments and advanced technologies. A miniaturised high-resolution camera (AMIE) for lunar surface imaging, a near-infrared point-spectrometer (SIR) for lunar mineralogy investigation, and a very compact X-ray spectrometer (D-CIXS) with a new type of detector and micro-collimator which will provide fluorescence spectroscopy and imagery of the Moon's surface elemental composition. The payload also includes an experiment (KaTE) aimed at demonstrating deep-space telemetry and telecommand communications in the X and Ka-bands, a radio-science experiment (RSIS), a deep space optical link (Laser-Link Experiment), using the ESA Optical Ground station in Tenerife, and the validation of a system of autonomous navigation SMART-1 lunar science investigations include studies of the chemical (OBAN) based on image processing. SMART-1 lunar science investigations include studies of the chemical composition and evolution of the Moon, of geophysical processes (volcanism, tectonics, cratering, erosion, deposition of ices and volatiles) for comparative planetology, and high resolution studies in preparation for future steps of lunar exploration. The mission could address several topics such as the accretional processes that led to the formation of planets, and the origin of the

  17. Coloration and oxygen vacancies in wide band gap oxide semiconductors: Absorption at metallic nanoparticles induced by vacancy clustering—A case study on indium oxide

    SciTech Connect

    Albrecht, M. Schewski, R.; Irmscher, K.; Galazka, Z.; Markurt, T.; Naumann, M.; Schulz, T.; Uecker, R.; Fornari, R.; Meuret, S.; Kociak, M.

    2014-02-07

    In this paper, we show by optical and electron microscopy based investigations that vacancies in oxides may cluster and form metallic nanoparticles that induce coloration by extinction of visible light. Optical extinction in this case is caused by generation of localized surface plasmon resonances at metallic particles embedded in the dielectric matrix. Based on Mie's approach, we are able to fit the absorption due to indium nanoparticles in In{sub 2}O{sub 3} to our absorption measurements. The experimentally found particle distribution is in excellent agreement with the one obtained from fitting by Mie theory. Indium particles are formed by precipitation of oxygen vacancies. From basic thermodynamic consideration and assuming theoretically calculated activation energies for vacancy formation and migration, we find that the majority of oxygen vacancies form just below the melting point. Since they are ionized at this temperature they are Coulomb repulsive. Upon cooling, a high supersaturation of oxygen vacancies forms in the crystal that precipitates once the Fermi level crosses the transition energy level from the charged to the neutral charge state. From our considerations we find that the ionization energy of the oxygen vacancy must be higher than 200 meV.

  18. Resonance-Enhanced Raman Scattering of Ring-Involved Vibrational Modes in the (1)B(2u) Absorption Band of Benzene, Including the Kekule Vibrational Modes ν(9) and ν(10).

    PubMed

    Willitsford, Adam H; Chadwick, C Todd; Kurtz, Stewart; Philbrick, C Russell; Hallen, Hans

    2016-02-04

    Resonance Raman spectroscopy provides much stronger Raman signal levels than its off-resonant counterpart and adds selectivity by excitation tuning. Raman preresonance of benzene has been well studied. On-resonance studies, especially at phonon-allowed absorptions, have received less attention. In this case, we observe resonance of many of the vibration modes associated motion of the carbons in the ring while tuning over the (1)B2u absorption, including the related ν9 (CC stretch Herzberg notation, ν14 Wilson notation) and ν10 (CH-parallel bend Herzberg notation, ν15 Wilson notation) vibrational modes along with the ν2 (CC-stretch or ring-breathing Herzberg notation, ν1 Wilson notation) mode and multiples of the ν18 (CCC-parallel bend Herzberg notation, ν6 Wilson notation) vibrational mode. The ring-breathing mode is found to mix with the b2u modes creating higher frequency composites. Through the use of an optical parametric oscillator (OPO) to tune through the (1)B2u absorption band of liquid benzene, a stiffening (increase in energy) of the vibrational modes is observed as the excitation wavelength nears the (1)B2u absorption peak of the isolated molecule (vapor) phase. The strongest resonance amplitude observed is in the 2 × ν18 (e2g) mode, with nearly twice the intensity of the ring-breathing mode, ν2. Several overtones and combination modes, especially with ν2 (a1g), are also observed to resonate. Raman resonances on phonon-allowed excitations are narrow and permit the measurement of vibrations not Raman-active in the ground state.

  19. Microwave absorption properties of planar-anisotropy Ce2Fe17N3-δ powders/Silicone composite in X-band

    NASA Astrophysics Data System (ADS)

    Gu, Xisheng; Tan, Guoguo; Chen, Shuwen; Man, Qikui; Chang, Chuntao; Wang, Xinmin; Li, Run-Wei; Che, Shenglei; Jiang, Liqiang

    2017-02-01

    The soft-magnetic properties of planar-anisotropy Ce2Fe17N3-δ powders were reported, and reflection loss (RL) of the powders/Silicone composites with various volume concentrations have been studied in 0.1-18 GHz frequency range. It was found that the optimal RL of this composite absorber with a thickness of 1.72 mm is -60.5 dB at 9.97 GHz and the RL is less than -10 dB in the whole X-band (8-12 GHz). The bandwidth with RL exceeding -10 dB and -20 dB are 5.24 GHz and 1.32 GHz, respectively. Furthermore, all the optimal RL value of the composite with the thickness less than 2.13 mm can reach -20 dB in the range of 8-17 GHz, which indicates that the Ce2Fe17N3-δ/Silicone composite absorber will be a promising candidate in higher gigahertz frequency especially in X-band.

  20. ESA Unveils Its New Comet Chaser.

    NASA Astrophysics Data System (ADS)

    1999-07-01

    The objective is to study one of these primordial objects at close quarters by placing a lander on its surface and chasing, with an orbiter, the comet for millions of kilometres through space. Comets - among the oldest (4.6 billion years!) and last altered objects in the solar system - are regarded as the building blocks from which the planets formed. Thus the Rosetta's discoveries will allow the scientists to learn more about birth and evolution of the planets and about the origin of life on the Earth. The final design of the Rosetta orbiter will be revealed for the first time at the Royal Society in London on 1 July when a 1:4 scale model will be unveiled by ESA's Director of Science, Prof.. Roger Bonnet. (The full size version of the spacecraft is 32 metres across, so large that it would stretch the entire width of a football pitch. Almost 90 of this is accounted for by the giant solar panels which are needed to provide electrical power in the dark depths of the Solar System). "Rosetta is a mission of major scientific importance," said Prof. Bonnet. "It will build on the discoveries made by Giotto and confirm ESA's leading role in the exploration of the Solar System and the Universe as a whole." The timing of this event has been chosen to coincide with the London meeting of the Rosetta Science Working Team and the second Earth flyby of the now non-operational Giotto spacecraft. In addition, the opening of the British Museum's 'Cracking Codes' Exhibition, for which the Rosetta Stone is the centrepiece, is set to take place on 10 July. The Rosetta mission. Rosetta is the third Cornerstone in ESA's 'Horizon 2000' long-term scientific programme. It will be launched by Ariane 5 rocket from Kourou spaceport in French Guiana in January 2003. In order to gain sufficient speed to reach the distant comet, Rosetta will require gravity assists from the Earth (twice) and Mars. After swinging around Mars in May 2005, Rosetta will return to Earth's vicinity in October 2005 and

  1. Operation IceBridge/ESA Collaboration Benefits All

    NASA Video Gallery

    For the second straight year, NASA's Operation IceBridge is collaborating with the European Space Agency's CryoVEx program, flying aircraft low over Arctic sea ice while ESA's CryoSat satellite orb...

  2. Induced changes in refractive index, optical band gap, and absorption edge of polycarbonate-SiO2 thin films by Vis-IR lasers

    NASA Astrophysics Data System (ADS)

    Ehsani, Hassan; Akhoondi, Somaieh

    2016-09-01

    In this experimental work, we have studied induced changes in refractive index, extinction coefficient, and optical band-gap of Bisphenol-A-polycarbonate (BPA-PC) coated with a uniform and thin, anti-scratch SiO2 film irradiated by visible to near-infrared lasers at 532 nm (green),650 nm(red), and 980 nm (IR)wavelength lasers with different energy densities. Our lasers sources are indium-gallium-aluminum-phosphide, second harmonic of neodymium-YAG-solid state lasers and gallium-aluminum-arsenide-semiconductor laser. The energy densities of our sources have been changed by changing the spot size of incident laser. samples transmission spectra were monitored by carry500 spectrophotometer and induced changes in optical properties are evaluated by using, extrapolation of the transmission spectrum through Swanepoel method and computer application

  3. Evaluation of SCIAMACHY Oxygen A band cloud heights using Cloudnet measurements

    NASA Astrophysics Data System (ADS)

    Wang, P.; Stammes, P.

    2014-05-01

    Two SCIAMACHY (SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY) O2 A band cloud height products are evaluated using ground-based radar/lidar measurements between January 2003 and December 2011. The products are the ESA (European Space Agency) Level 2 (L2) version 5.02 cloud top height and the FRESCO (Fast Retrieval Scheme for Clouds from the Oxygen A band) version 6 cloud height. The radar/lidar profiles are obtained at the Cloudnet sites of Cabauw and Lindenberg, and are averaged for 1 h centered at the SCIAMACHY overpass time. In total we have 217 cases of single-layer clouds and 204 cases of multilayer clouds. We find that the ESA L2 cloud top height has a better agreement with the Cloudnet cloud top height than the Cloudnet cloud middle height. The ESA L2 cloud top height is on average 0.4 km higher than the Cloudnet cloud top height, with a standard deviation of 3.1 km. The FRESCO cloud height is closer to the Cloudnet cloud middle height than the Cloudnet cloud top height. The mean difference between the FRESCO cloud height and the Cloudnet cloud middle height is -0.1 km with a standard deviation of 1.9 km. The ESA L2 cloud top height is higher than the FRESCO cloud height. The differences between the SCIAMACHY cloud (top) height and the Cloudnet cloud top height are linked to cloud optical thickness. The SCIAMACHY cloud height products are further compared to the Cloudnet cloud top height and the Cloudnet cloud middle height in 1 km bins. For single-layer clouds, the difference between the ESA L2 cloud top height and the Cloudnet cloud top height is less than 1 km for each cloud bin at 3-7 km. The difference between the FRESCO cloud height and the Cloudnet cloud middle height is less than 1 km for each cloud bin at 0-6 km. The results are similar for multilayer clouds, but the percentage of cases having a bias within 1 km is smaller than for single-layer clouds. We may conclude that the FRESCO cloud height is accurate for low and middle

  4. ESA Experiments with the European Modular Cultivation System (EMCS)

    NASA Astrophysics Data System (ADS)

    Brillouet, Claude; Briganti, Luca; Schwarzwalder, Achim

    2008-06-01

    The European Modular Cultivation System (EMCS) is an ESA developed facility dedicated to gravitational biology and especially to plant research. However, experiments using small animals, like insects and small invertebrates are also possible. EMCS is onboard the International Space Station (ISS) since July 2006 and four experiments, including two from ESA, have been already performed. Several others are in their final development phase and shall be flown within the next following years.

  5. The ESA Planetary Science Archive User Group (PSA-UG)

    NASA Astrophysics Data System (ADS)

    Pio Rossi, Angelo; Cecconi, Baptiste; Fraenz, Markus; Hagermann, Axel; Heather, David; Rosenblatt, Pascal; Svedhem, Hakan; Widemann, Thomas

    2014-05-01

    ESA has established a Planetary Science Archive User Group (PSA-UG), with the task of offering independent advice to ESA's Planetary Science Archive (e.g. Heather et al., 2013). The PSA-UG is an official and independent body that continuously evaluates services and tools provided by the PSA to the community of planetary data scientific users. The group has been tasked with the following top level objectives: a) Advise ESA on future development of the PSA. b) Act as a focus for the interests of the scientific community. c) Act as an advocate for the PSA. d) Monitor the PSA activities. Based on this, the PSA-UG will report through the official ESA channels. Disciplines and subjects represented by PSA-UG members include: Remote Sensing of both Atmosphere and Solid Surfaces, Magnetospheres, Plasmas, Radio Science and Auxilliary data. The composition of the group covers ESA missions populating the PSA both now and in the near future. The first members of the PSA-UG were selected in 2013 and will serve for 3 years, until 2016. The PSA-UG will address the community through workshops, conferences and the internet. Written recommendations will be made to the PSA coordinator, and an annual report on PSA and the PSA-UG activities will be sent to the Solar System Exploration Working Group (SSEWG). Any member of the community and planetary data user can get in touch with individual members of the PSA-UG or with the group as a whole via the contacts provided on the official PSA-UG web-page: http://archives.esac.esa.int/psa/psa-ug. The PSA is accessible via: http://archives.esac.esa.int/psa References: Heather, D., Barthelemy, M., Manaud, N., Martinez, S., Szumlas, M., Vazquez, J. L., Osuna, P. and the PSA Development Team (2013) ESA's Planetary Science Archive: Status, Activities and Plans. EuroPlanet Sci. Congr. #EPSC2013-626

  6. Low-temperature high-resolution absorption spectrum of 14NH3 in the ν1+ν3 band region (1.51 μm)

    NASA Astrophysics Data System (ADS)

    Földes, T.; Golebiowski, D.; Herman, M.; Softley, T. P.; Di Lonardo, G.; Fusina, L.

    2014-09-01

    Jet-cooled spectra of 14NH3 and 15NH3 in natural abundance were recorded using cavity ring-down (CRDS, 6584-6670 cm-1) and cavity enhanced absorption (CEAS, 6530-6700 cm-1) spectroscopy. Line broadening effects in the CRDS spectrum allowed lines with J″-values between 0 and 3 to be identified. Intensity ratios in 14NH3 between the jet-cooled CRDS and literature room-temperature data from Sung et al. (J. Quant. Spectrosc. Radiat. Transfer, 113 (2012), 1066) further assisted the line assignments. Ground state combination differences were extensively used to support the assignments, providing reliable values for J, K and inversion symmetry of the ground state vibrational levels. CEAS data helped in this respect for the lowest J lines, some of which are saturated in the CRDS spectrum. Further information on a/s doublets arose from the observed spectral structures. Thirty-two transitions of 14NH3 were assigned in this way and a limited but significant number (19) of changes in the assignments results, compared to Sung et al. or to Cacciani et al. (J. Quant. Spectrosc. Radiat. Transfer, 113 (2012), 1084). Sixteen known and 25 new low-J transitions were identified for 15NH3 in the CRDS spectrum but the much scarcer literature information did not allow for any more refined assignment. The present line position measurements improve on literature values published for 15NH3 and on some line positions for 14NH3.

  7. Effect of Substitution of Mn, Cu, and Zr on the Structural, Magnetic, and Ku-Band Microwave-Absorption Properties of Strontium Hexaferrite Nanoparticles

    NASA Astrophysics Data System (ADS)

    Rostami, Mohammad; Moradi, Mahmood; Alam, Reza Shams; Mardani, Reza

    2016-08-01

    The ferrites with the compositions of SrMn x Cu x Zr2 x Fe(12-4 x)O19 ( x = 0.0, 0.2, 0.3, 0.4, and 0.5) are synthesized by the coprecipitation method. The formation of M-type hexaferrite is confirmed by x-ray diffraction (XRD) and Fourier transform infrared (FTIR) analyses. The morphology of the samples is shown by field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) microscopy. Vibrating sample magnetometer (VSM) analysis has been used for the investigation of the magnetic properties, and the reason for the changes in the magnetic properties as a result of doping, are expressed. The values of coercivity decrease by increasing the amount of substitution, which could be related to the modification of anisotropy form the c-axis toward the c-plane. Finally, we have used vector network analysis to investigate the microwave absorption properties. We find that the samples with the composition of SrMn0.4Cu0.4Zr0.8Fe10.4O19 have the largest reflection loss and the widest bandwidth among these samples.

  8. 13C(16)O(2): Global Treatment of Vibrational-Rotational Spectra and First Observation of the 2nu(1) + 5nu(3) and nu(1) + 2nu(2) + 5nu(3) Absorption Bands.

    PubMed

    Tashkun; Perevalov; Teffo; Lecoutre; Huet; Campargue; Bailly; Esplin

    2000-04-01

    The effective operator approach is applied to the calculation of both line positions and line intensities of the (13)C(16)O(2) molecule. About 11 000 observed line positions of (13)C(16)O(2) selected from the literature have been used to derive 84 parameters of a reduced effective Hamiltonian globally describing all known vibrational-rotational energy levels in the ground electronic state. The standard deviation of the fit is 0.0015 cm(-1). The eigenfunctions of this effective Hamiltonian have then been used in fittings of parameters of an effective dipole-moment operator to more than 600 observed line intensities of the cold and hot bands covering the nu(2) and 3nu(2) regions. The standard deviations of the fits are 3.2 and 12.0% for these regions, respectively. The quality of the fittings and the extrapolation properties of the fitted parameters are discussed. A comparison of calculated line parameters with those provided by the HITRAN database is given. Finally, the first observations of the 2nu(1) + 5nu(3) and nu(1) + 2nu(2) + 5nu(3) absorption bands by means of photoacoustic spectroscopy (PAS) is presented. The deviations of predicted line positions from observed ones is found to be less than 0.1 cm(-1), and most of them lie within the experimental accuracy (0.007 cm(-1)) once the observed line positions are included in the global fit. Copyright 2000 Academic Press.

  9. ANOMALOUS DIFFUSE INTERSTELLAR BANDS IN THE SPECTRUM OF HERSCHEL 36. I. OBSERVATIONS OF ROTATIONALLY EXCITED CH AND CH{sup +} ABSORPTION AND STRONG, EXTENDED REDWARD WINGS ON SEVERAL DIBs

    SciTech Connect

    Dahlstrom, Julie; York, Donald G.; Welty, Daniel E.; Oka, Takeshi; Johnson, Sean; Jiang Zihao; Sherman, Reid; Hobbs, L. M.; Friedman, Scott D.; Sonnentrucker, Paule; Rachford, Brian L.; Snow, Theodore P.

    2013-08-10

    Anomalously broad diffuse interstellar bands (DIBs) at 5780.5, 5797.1, 6196.0, and 6613.6 A are found in absorption along the line of sight to Herschel 36, the star illuminating the bright Hourglass region of the H II region Messier 8. Interstellar absorption from excited CH{sup +} in the J = 1 level and from excited CH in the J = 3/2 level is also seen. To our knowledge, neither those excited molecular lines nor such strongly extended DIBs have previously been seen in absorption from interstellar gas. These unusual features appear to arise in a small region near Herschel 36 which contains most of the neutral interstellar material in the sight line. The CH{sup +} and CH in that region are radiatively excited by strong far-IR radiation from the adjacent infrared source Her 36 SE. Similarly, the broadening of the DIBs toward Herschel 36 may be due to radiative pumping of closely spaced high-J rotational levels of relatively small, polar carrier molecules. If this picture of excited rotational states for the DIB carriers is correct and applicable to most DIBs, the 2.7 K cosmic microwave background may set the minimum widths (about 0.35 A) of known DIBs, with molecular processes and/or local radiation fields producing the larger widths found for the broader DIBs. Despite the intense local UV radiation field within the cluster NGC 6530, no previously undetected DIBs stronger than 10 mA in equivalent width are found in the optical spectrum of Herschel 36, suggesting that neither dissociation nor ionization of the carriers of the known DIBs by this intense field creates new carriers with easily detectable DIB-like features. Possibly related profile anomalies for several other DIBs are noted.

  10. LINE ABSORPTION OSCILLATOR STRENGTHS FOR THE c'{sub 4}{sup 1}{Sigma}{sup +}{sub u}(3)-X{sup 1}{Sigma}{sup +}{sub g}(0-5) BANDS IN N{sub 2}

    SciTech Connect

    Lavin, C.; Velasco, A. M.

    2011-09-20

    Theoretical absorption oscillator strengths and emission branching ratios for rotational lines of the c'{sub 4}{sup 1}{Sigma}{sup +}{sub u}(3)-X{sup 1}{Sigma}{sup +}{sub g}(0-5) bands of molecular nitrogen are reported. The calculations have been performed with the molecular quantum defect orbital method, which has proved to be reliable in previous studies of rovibronic transitions in diatomic molecules. The strong interaction between c'{sub 4}{sup 1}{Sigma}{sup +}{sub u}(3) and b' {sup 1}{Sigma}{sup +}{sub u}(10) states has been analyzed through an interaction matrix that includes rotational terms. Owing to the perturbation, the c'{sub 4}{sup 1}{Sigma}{sup +}{sub u}(3)-X{sup 1}{Sigma}{sup +}{sub g}(0), c'{sub 4}{sup 1}{Sigma}{sup +}{sub u}(3)-X{sup 1}{Sigma}{sup +}{sub g}(1), and c'{sub 4}{sup 1}{Sigma}{sup +}{sub u}(3)-X{sup 1}{Sigma}{sup +}{sub g}(5) bands are not weak, in contrast to what would be expected on the basis of the Franck-Condon principle. Moreover, the intensity distribution of the rotational lines within each of the vibronic bands deviates from considerations based on Hoenl-London factors. In this work, we provide data that may be useful to interpret spectra from atmospheres of the Earth, Titan, and Triton, in which transitions from the c'{sub 4}{sup 1}{Sigma}{sup +}{sub u}(3) level have been detected.

  11. The ESA Planetary Science Archive User Group (PSA-UG)

    NASA Astrophysics Data System (ADS)

    Rossi, A. P.; Cecconi, B.; Fraenz, M.; Hagermann, A.; Heather, D.; Rosenblatt, P.; Svedhem, H.; Widemann, T.

    2014-04-01

    ESA has established a Planetary Science Archive User Group (PSA-UG), with the task of offering independent advice to ESA's Planetary Science Archive (e.g. Heather et al., 2013). The PSA-UG is an official and independent body that continuously evaluates services and tools provided by the PSA to the community of planetary data scientific users. The group has been tasked with the following top level objectives: a) Advise ESA on future development of the PSA. b) Act as a focus for the interests of the scientific community. c) Act as an advocate for the PSA. d) Monitor the PSA activities. Based on this, the PSA-UG will report through the official ESA channels. Disciplines and subjects represented by PSA-UG members include: Remote Sensing of both Atmosphere and Solid Surfaces, Magnetospheres, Plasmas, Radio Science and Auxilliary data. The composition of the group covers ESA missions populating the PSA both now and in the near future. The first members of the PSA-UG were selected in 2013 and will serve for 3 years, until 2016. The PSA-UG will address the community through workshops, conferences and the internet. Written recommendations will be made to the PSA coordinator, and an annual report on PSA and the PSA-UG activities will be sent to the Solar System Exploration Working Group (SSEWG). Any member of the community and planetary data user can get in touch with individual members of the PSA-UG or with the group as a whole via the contacts provided on the official PSA-UG web-page: http://archives.esac.esa.int/psa/psa-ug The PSA is accessible via: http://archives.esac.esa.int/psa

  12. Lidar instruments for ESA Earth observation missions

    NASA Astrophysics Data System (ADS)

    Hélière, Arnaud; Armandillo, Errico; Durand, Yannig; Culoma, Alain; Meynart, Roland

    2004-06-01

    The idea of deploying a lidar system on an Earth-orbiting satellite stems from the need for continuously providing profiles of our atmospheric structure with high accuracy and resolution and global coverage. Interest in this information for climatology, meteorology and the atmospheric sciences in general is huge. Areas of application range from the determination of global warming and greenhouse effects, to monitoring the transport and accumulation of pollutants in the different atmospheric regions (such as the recent fires in Southeast Asia), to the assessment of the largely unknown microphysical properties and the structural dynamics of the atmosphere itself. Spaceborne lidar systems have been the subject of extensive investigations by the European Space Agency since mid 1970's, resulting in mission and instrument concepts, such as ATLID, the cloud backscatter lidar payload of the EarthCARE mission, ALADIN, the Doppler wind lidar of the Atmospheric Dynamics Mission (ADM) and more recently a water vapour Differential Absorption Lidar considered for the WALES mission. These studies have shown the basic scientific and technical feasibility of spaceborne lidars, but they have also demonstrated their complexity from the instrument viewpoint. As a result, the Agency undertook technology development in order to strengthen the instrument maturity. This is the case for ATLID, which benefited from a decade of technology development and supporting studies and is now studied in the frame of the EarthCARE mission. ALADIN, a Direct Detection Doppler Wind Lidar operating in the Ultra-Violet, will be the 1st European lidar to fly in 2007 as payload of the Earth Explorer Core Mission ADM. WALES currently studied at the level of a phase A, is based upon a lidar operating at 4 wavelengths in near infrared and aims to profile the water vapour in the lower part of the atmosphere with high accuracy and low bias. Lastly, the European Space Agency is extending the lidar instrument field

  13. Coronal sounding with three ESA spacecraft during solar conjunction: Radial dependence of radio signal fluctuation spectra

    NASA Astrophysics Data System (ADS)

    Efimov, Anatoli; Lukinina, L. A.; Samoznaev, L. N.; Rudash, V. K.; Chashei, I. V.; Bird, Michael; Paetzold, Martin

    Coronal radio sounding experiments were carried out using the coherent dual-frequency carrier signals of the three ESA spacecraft Mars Express (MEX), Venus Express (VEX) and Rosetta (ROS) during their solar conjunctions in 2004, 2006 and 2008/2009. The measurements ana-lyzed in this work are the signal frequency and amplitude recorded at both the NASA and ESA ground tracking stations (sample rate: 1 Hz). The solar activity was quite low during these measurement opportunities, particularly for the conjunction in 2008/2009 (average sunspot number = 2.3). Spectral analysis of the frequency records provides two quantities used to characterize coronal turbulence: the intensity of the differential frequency fluctuations σf and the spectral index of the temporal frequency fluctuation spectra αf . The mean frequency fluctuation can be described by a radial power-law σf ∝ R-a . The spectral index, roughly constant at αf ≈ 0.67 for heliocentric distances beyond a certain solar offset distance RKOL , decreases gradually toward smaller solar offset distances. An unexplained discrepancy is found between the observed difference in amplitude fluctuations from S-Band to X-Band and the difference expected from theory.

  14. Aerosol Climate Time Series in ESA Aerosol_cci

    NASA Astrophysics Data System (ADS)

    Popp, Thomas; de Leeuw, Gerrit; Pinnock, Simon

    2016-04-01

    Within the ESA Climate Change Initiative (CCI) Aerosol_cci (2010 - 2017) conducts intensive work to improve algorithms for the retrieval of aerosol information from European sensors. Meanwhile, full mission time series of 2 GCOS-required aerosol parameters are completely validated and released: Aerosol Optical Depth (AOD) from dual view ATSR-2 / AATSR radiometers (3 algorithms, 1995 - 2012), and stratospheric extinction profiles from star occultation GOMOS spectrometer (2002 - 2012). Additionally, a 35-year multi-sensor time series of the qualitative Absorbing Aerosol Index (AAI) together with sensitivity information and an AAI model simulator is available. Complementary aerosol properties requested by GCOS are in a "round robin" phase, where various algorithms are inter-compared: fine mode AOD, mineral dust AOD (from the thermal IASI spectrometer, but also from ATSR instruments and the POLDER sensor), absorption information and aerosol layer height. As a quasi-reference for validation in few selected regions with sparse ground-based observations the multi-pixel GRASP algorithm for the POLDER instrument is used. Validation of first dataset versions (vs. AERONET, MAN) and inter-comparison to other satellite datasets (MODIS, MISR, SeaWIFS) proved the high quality of the available datasets comparable to other satellite retrievals and revealed needs for algorithm improvement (for example for higher AOD values) which were taken into account for a reprocessing. The datasets contain pixel level uncertainty estimates which were also validated and improved in the reprocessing. For the three ATSR algorithms the use of an ensemble method was tested. The paper will summarize and discuss the status of dataset reprocessing and validation. The focus will be on the ATSR, GOMOS and IASI datasets. Pixel level uncertainties validation will be summarized and discussed including unknown components and their potential usefulness and limitations. Opportunities for time series extension

  15. Band models and correlations for infrared radiation

    NASA Technical Reports Server (NTRS)

    Tiwari, S. N.

    1975-01-01

    Absorption of infrared radiation by various line and band models are briefly reviewed. Narrow band model relations for absorptance are used to develop 'exact' formulations for total absorption by four wide band models. Application of a wide band model to a particular gas largely depends upon the spectroscopic characteristic of the absorbing-emitting molecule. Seven continuous correlations for the absorption of a wide band model are presented and each one of these is compared with the exact (numerical) solutions of the wide band models. Comparison of these results indicate the validity of a correlation for a particular radiative transfer application. In radiative transfer analyses, use of continuous correlations for total band absorptance provides flexibilities in various mathematical operations.

  16. Packet utilisation definitions for the ESA XMM mission

    NASA Technical Reports Server (NTRS)

    Nye, H. R.

    1994-01-01

    XMM, ESA's X-Ray Multi-Mirror satellite, due for launch at the end of 1999 will be the first ESA scientific spacecraft to implement the ESA packet telecommand and telemetry standards and will be the first ESOC-controlled science mission to take advantage of the new flight control system infrastructure development (based on object-oriented design and distributed-system architecture) due for deployment in 1995. The implementation of the packet standards is well defined at packet transport level. However, the standard relevant to the application level (the ESA Packet Utilization Standard) covers a wide range of on-board 'services' applicable in varying degrees to the needs of XMM. In defining which parts of the ESA PUS to implement, the XMM project first considered the mission objectives and the derived operations concept and went on to identify a minimum set of packet definitions compatible with these aspects. This paper sets the scene as above and then describes the services needed for XMM and the telecommand and telemetry packet types necessary to support each service.

  17. ESA's Drop Tower Utilisation Activities 2000 to 2011

    NASA Astrophysics Data System (ADS)

    Kufner, Ewald; Blum, J.; Callens, N.; Eigenbrod, Ch.; Koudelka, O.; Orr, A.; Rosa, C. C.; Vedernikov, A.; Will, S.; Reimann, J.; Wurm, G.

    2011-11-01

    The European Space Research and Technology Center ESTEC, ESA's premises in Noordwijk, The Netherlands, has a long lasting cooperation with the ZARM-FAB (Centre of Applied Space Technology and Microgravity—Drop Tower Operation and Service Company) in Bremen on the utilization of the Drop Tower for ground-based microgravity research and space hardware development studies. During the period January 2000 to December 2011 ESA will have procured in total some 840 drops addressing a variety of scientific and technological disciplines. The experiments are usually carried out in campaigns of 15 to 20 drops each, with an annual average of about 5 campaigns. The cooperation agreement between ESA and the ZARM-FAB includes experiment preparation advice by ZARM's experts, the integration of the hardware into the drop capsule, dedicated safety reviews, the execution of the drop or catapult experiments, the post-flight payload de-integration as well as the handover of acquired data to the experimenters. The experiment hardware itself is provided by the scientists or has to be procured from sources outside of ESA's drop tower utilization contract. ESA appreciates the cooperation of the ZARM-FAB in Bremen whose drop- and catapult facility provides excellent microgravity quality, is operated by a highly competent, flexible and extremely supportive expert team, allows campaign integration at relatively short notice throughout the entire year, offers real-time experiment operations and immediately after each drop delivers experiment results and provides on-site hardware modification possibilities.

  18. A vista of new knowledge from ESA's Hipparcos astronomy mission

    NASA Astrophysics Data System (ADS)

    1997-05-01

    Hipparcos is a milestone in the history of astronomy. In 1985 the American physicist Freeman J. Dyson hailed Hipparcos as the first major new development in space science to come from outside the United States. The spacecraft operated in orbit 1989-93, measuring the angles between stars in the sky. Over a further three years, computing teams across Europe generated a consistent, high-precision plot of 118,000 stars in the Hipparcos Catalogue and somewhat less accurate (but still unprecedented) data on a million stars in the Tycho Catalogue. The distances, motions, pairings and variability of stars are now known far more accurately than ever before. Hipparcos will make an impact on every branch of astronomy, from the Solar System to the history of the Universe, and especially on theories of stars and their evolution. For almost a year, astronomers most closely associated with the mission have had an early view of the completed catalogues and in Venice they will summarize their initial results. The Hipparcos data will be published in June, as an extraordinary contribution from Europe to astronomy all around the world. The success of Hipparcos has created problems for the organizers of Venice symposium. Altogether 190 scientific papers were offered for presentation by various groups of astronomers. With three mornings and three afternoons available for the main scientific sessions, 67 oral presentations are accommodated, by restricting speakers to 10-15 minutes each. For the rest, there will a generous display of results in the form of posters. Thus Hipparcos will be celebrated by a vista of new knowledge. The stars are looking younger Already Hipparcos seems to cure a headache concerning the ages of stars. As recently as last year, astronomers were perplexed by a contradiction between their estimates of the age of the Universe, and stars that seemed to be older. An early Hipparcos result announced in February 1997 (ESA Information Note 04/97) concerned the winking

  19. ESA is now a major player in global space science

    NASA Astrophysics Data System (ADS)

    1997-07-01

    * Results from the star-fixing satellite Hipparcos, released this summer to the world's astronomers, give the positions and motions of 118,000 stars a hundred times more accurately than ever before. * Every day the Infrared Space Observatory, ISO, examines 45 cosmic objects on average at many different wavelengths never observable before, giving fresh insights into cosmic history and chemistry. * Invaluable new knowledge of the Sun comes from SOHO, the Solar and Heliospheric Observatory, which is the first spacecraft able to observe the Sun's deep interior as well as its stormy surface and atmosphere. Besides these missions making present headlines, several other spacecraft are helping to fulfil ESA's scientific objectives. * 2 - * The launch in October 1997 of ESA's probe Huygens, aboard the Cassini spacecraft bound for Saturn, foreshadows a breakthrough in planetary science in 2004. That is when Huygens will carry its scientific instruments into the unique and puzzling atmosphere of Saturn's moon Titan. * Ulysses, also built in Europe, is exploring hitherto unknown regions of space, after making the first-ever visit to the Sun's polar regions in 1994-95. It will return to the Sun in 2000-2001, to observe the effects of the climax of solar activity due at that time. * The Cluster 2 mission, announced in April 1997 and to be launched in 2000, will explore the Earth's space environment far more throughly than ever before. ESA's decision to replace the four Cluster satellites lost in a launch accident in 1996 ensures that Europe will continue as the leader in solar-terrestrial research in space. * An example of the three unique 58-mirror X-ray telescopes for the XMM mission was unveiled for the press in May 1997. When it goes into orbit in 1999 XMM will make, in seconds, observations of cosmic objects that took hours with previous X-ray astronomy missions. * The Hubble Space Telescope, in which ESA is a partner, continues to deliver the sharpest pictures of the

  20. ESA's Earth Observation Programmes in the Changing Anthropocene

    NASA Astrophysics Data System (ADS)

    Liebig, Volker

    2016-07-01

    The intervention will present ESA's Earth Observation programmes and their relevance to studying the anthropocene. ESA's Earth observation missions are mainly grouped into three categories: The Sentinel satellites in the context of the European Copernicus Programme, the scientific Earth Explorers and the meteorological missions. Developments, applications and scientific results for the different mission types will be addressed, along with overall trends and strategies. The Earth Explorers, who form the science and research element of ESA's Living Planet Programme, focus on the atmosphere, biosphere, hydrosphere, cryosphere and Earth's interior. The Earth Explorers also aim at learning more about the interactions between these components and the impact that human activity is having on natural Earth processes. The Sentinel missions provide accurate, timely, long term and uninterrupted data to provide key information services, improving the way the environment is managed, and helping to mitigate the effects of climate change. The operational Sentinel satellites can also be exploited for scientific studies of the anthropocene. In the anthropocene human activities affect the whole planet and space is a very efficient means to measure their impact, but for relevant endeavours to be successful they can only be carried out in international cooperation. ESA maintains long-standing partnerships with other space agencies and institutions worldwide. In running its Earth observation programmes, ESA responds to societal needs and challenges and to requirements resulting from political priorities set by decision makers. Activities related to Climate Change are a prime example. Within ESA's Climate Change Initiative, 13 Essential Climate Variables are constantly monitored to create a long-term record of key geophysical parameters.

  1. ESA on RAINEWS24: A Case Study of Television Communication

    NASA Astrophysics Data System (ADS)

    Sandrelli, S.

    2005-12-01

    In May 2000, ESRIN, the Italian establishment of the European Space Agency (ESA), started a collaboration with the television channel Rainews24. Rainews24 is the "allnews" channel of Italian public television (RAI) and is now about 10 years old. It transmits 24 hours a day and is the most watched all-news satellite channel in Italy. Each Thursday an ESA representative (Stefano Sandrelli) is interviewed by a professional RAI journalist in a 5-6 minute long slot that follows the 5 pm news bulletin. The broadcast is repeated late at night or in the early hours of Thursday and Friday. Interviews are strictly linked to the weekly news and are prepared on the morning of the same day by the ESA representative in collaboration with a RAI journalist. The subject is chosen from the most topical news items of the week: video, images and animations are provided by the ESA television service and by press agencies (Reuters etc.). The interviews are largely informal and resemble a dialogue rather than an academic discussion "from space". Even though they focus on ESA activities, they are not advertisements: space science and research is dealt with as a human activity, so both the positive and negative aspects of space exploration and exploitation may emerge. Although this outreach activity began as an experiment, the ESA interviews have become a fixed feature. As a result of five years of uninterrupted collaboration, over 200 interviews have been recorded, with about 30% of the interviews dedicated to pure astronomy. A welcome positive feature is that the interviews are seen by Rainews24 as an open source of daily news.

  2. Technology validation of the PLATO CCD at ESA

    NASA Astrophysics Data System (ADS)

    Prod'homme, Thibaut; Verhoeve, Peter; Beaufort, Thierry; Duvet, Ludovic; Lemmel, Frederic; Smit, Hans; Blommaert, Sander; Oosterbroek, Tim; van der Luijt, Cornelis; Visser, Ivo; Heijnen, Jerko; Butler, Bart

    2016-07-01

    PLATO { PLAnetary Transits and Oscillations of stars { is the third medium-class mission to be selected in the European Space Agency (ESA) Science and Robotic Exploration Cosmic Vision programme. Due for launch in 2025, the payload makes use of a large format (8 cm x 8 cm) Charge-Coupled Devices (CCDs) the e2v CCD270 operated at 4 MHz. The manufacture of such large device in large quantity constitutes an unprecedented effort. To de-risk the PLATO CCD procurement and aid the mission definition process, ESA's Payload Technology Validation team is characterizing the electro-optical performance of a number of PLATO devices before and after proton irradiation.

  3. ESA-SSA Review of Space Weather Measurement Requirements

    NASA Astrophysics Data System (ADS)

    Luntama, Juha-Pekka; Glover, Alexi; Hilgers, Alain

    2012-07-01

    The ESA Space Situational Awareness (SSA) Preparatory Programme was started in 2009. The objective of the programme is to support the European independent utilisation of and access to space. The first phase of the ESA SSA system development will be finished in 2012 and the next phase is foreseen to be started after the ESA Ministerial Council meeting in November 2012. The definition of measurement requirements for the Space Weather Segment (SWE) of the ESA SSA system has been based on the space weather service requirements defined the by expected users of the system. This document, SSA SWE Customer Requirements Document (CRD), has been defined in a iterative process together with the members of the SSA User Representative Group (URG) and the delegates representing the European states participating the programme. Based on the SWE CRD, ESA with the support of the European industry has produced two documents: SSA SWE System Requirements Document (SRD) and SSA SWE Product Specification (PS). SWE PS contains the requirements for the measurements data required by the SSA SWE system. The SWE PS document has been recently rigorously reviewed by the SSA URG in the framework of the SSA System Requirements Review (SRR). The support provided by the Steering Board of the ESA Space Weather Working Team (SWWT) in this review was extremely useful. The members of the SWWT SB representing the scientific community and the provisional service providers were able to give very detailed comments regarding the measurement requirements for accuracy, cadence, timeliness, etc. As these parameters will be provisional design and cost drivers for the ESA SSA system, definition of the appropriate values at this point in the programme is crucial. This paper provides an overview of the measurement requirements for the SWE Segment of the ESA SSA Programme. The paper discusses the requirement definition process, the customer and service provider inputs, and the critical requirements as they have

  4. ESA's CCD test bench for the PLATO mission

    NASA Astrophysics Data System (ADS)

    Beaufort, Thierry; Duvet, Ludovic; Bloemmaert, Sander; Lemmel, Frederic; Prod'homme, Thibaut; Verhoeve, Peter; Smit, Hans; Butler, Bart; van der Luijt, Cornelis; Heijnen, Jerko; Visser, Ivo

    2016-08-01

    PLATO { PLAnetary Transits and Oscillations of stars { is the third medium-class mission to be selected in the European Space Agency (ESA) Science and Robotic Exploration Cosmic Vision programme. Due for launch in 2025, the payload makes use of a large format (8 cm x 8 cm) Charge-Coupled Devices (CCDs), the e2v CCD270 operated at 4 MHz and at -70 C. To de-risk the PLATO CCD qualification programme initiated in 2014 and support the mission definition process, ESA's Payload Technology Validation section from the Future Missions Office has developed a dedicated test bench.

  5. NASA's Preparations for ESA's L3 Gravitational Wave Mission

    NASA Astrophysics Data System (ADS)

    Stebbins, Robin T.

    2016-01-01

    In November 2013, the European Space Agency (ESA) selected the science theme, the "Gravitational Universe," for its third large mission opportunity, known as 'L3,' under its Cosmic Vision Programme. The planned launch date is 2034. NASA is seeking a role as an international partner in L3. NASA is supporting: (1) US participation in early mission studies, (2) US technology development, (3) pre-decadal preparations, (4) ESA's LISA Pathfinder mission and (5) the ST7 Disturbance Reduction System project. This talk summarizes NASA's preparations for a future gravitational-wave mission.

  6. ESA's Venus Express to reach final destination

    NASA Astrophysics Data System (ADS)

    2006-04-01

    atmospheric bands in the infrared part of the spectrum. Through these, precious information about the lower layers of the atmosphere and even the surface can be gathered. The Venus Express mission will help find answers to several unsolved questions. How does the complex atmospheric dynamics and cloud system work? What causes the fast “super-rotation” of the atmosphere at the cloud top? And what is the origin of the double vortex at the north pole? Venus Express will also investigate the processes that determine the chemistry of the noxious Venusian atmosphere, which can be as hot as 500°C at the surface and is mainly composed of carbon dioxide, with clouds of sulphuric acid drops. It will study what role the greatest greenhouse effect in the solar system plays in the overall evolution of the Venusian climate. It will also help us to ascertain whether Venus provides a possible preview of a future Earth. Lastly, through combined analysis of the dense atmosphere and surface, Venus Express will help us to understand the planet’s geology and ascertain there are signs of present volcanic or seismic activity. “Venus Express to ground control” During the course of the nominal mission, Venus Express will communicate with Earth via ESA’s Cebreros ground station near Madrid. ESA’s New Norcia station in Australia will be used to support the VeRA radio science experiment.

  7. Full Spectral Resolution Data Generation from the Cross-track Infrared Sounder on S-NPP at NOAA and its Use to Investigate Uncertainty in Methane Absorption Band Near 7.66 µm

    NASA Astrophysics Data System (ADS)

    Xiong, X.; Peischl, J.; Ryerson, T. B.; Sasakawa, M.; Han, Y.; Chen, Y.; Wang, L.; Tremblay, D.; Jin, X.; Zhou, L.; Liu, Q.; Weng, F.; Machida, T.

    2015-12-01

    The Cross-track Infrared Sounder (CrIS) on Suomi National Polar-orbiting Partnership Satellite (S-NPP) is a Fourier transform spectrometer for atmospheric sounding. CrIS on S-NPP started to provide measurements in 1305 channels in its normal mode since its launch on November 2011 to December 4, 2014, and after that it was switched to the full spectral resolution (FSR) mode, in which the spectral resolutions are 0.625 cm-1 in all the MWIR (1210-1750 cm-1), SWIR (2155-2550 cm-1) and the LWIR bands (650-1095 cm-1) with a total of 2211 channels. While the NOAA operational Sensor Data Record (SDR) processing (IDPS) continues to produce the normal resolution SDRs by truncating full spectrum RDR data, NOAA STAR started to process the FSR SDRs data since December 4, 2014 to present, and the data is being delivered through NOAA STAR website (ftp://ftp2.star.nesdis.noaa.gov/smcd/xxiong/). The current FSR processing algorithm was developed on basis of the CrIS Algorithm Development Library (ADL), and is the baseline of J-1 CrIS SDR algorithm. One major benefit to use the FSR data is to improve the retrieval of atmospheric trace gases, such as CH4, CO and CO2 . From our previous studies to retrieve CH4 using Atmospheric Infrared Sounder (AIRS) and Infrared Atmospheric Sounding Interferometer (IASI), it was found the uncertainty in the CH4 absorption band is up to 1-2%. So, in this study we computed the radiance using the community radiative transfer model (CRTM) and line-by-line model, with the inputs of "truth" of atmospheric temperature and moisture profiles from ECMWF model (and/or RAOB sounding) and CH4 profiles from in-situ aircraft measurements, then convoluted with the response function of CrIS. The difference between the simultaed radiance and the collocated CrIS FSR data is used to exam the uncertainty in these strong absorption channels.Through the improved fitting to the transmittance in these channels, it is expected to improve the retrieval of CH4 using CrIS on S

  8. The efficacy of L. (L.) chagasi excreted-secreted antigens (ESAs) for visceral leishmaniasis diagnosis is due to low levels of cross-reactivity.

    PubMed

    Pinedo-Cancino, Viviana; Kesper, Norival; Barbiéri, Clara Lúcia; Lindoso, José Angelo Lauletta; Umezawa, Eufrosina Setsu

    2013-03-01

    The analysis of promastigote excreted-secreted antigen (ESA) reactivity with 53 visceral leishmaniasis (VL) cases showed that each sample reacted regardless of the antigen or the Leishmania species used in enzyme-linked immunosorbent assay (ELISA) displayed 100% positivity with the L. (L.) chagasi ESA-blot recognizing bands of molecular weight ranging from 26.5 to 31.5 kDa. The analysis of 160 non-visceral cases showed that 5% of the samples cross-reacted with the L. (L.) chagasi ESA-ELISA and 9.4% reacted with the ESA isolated from L. (L.) amazonensis and L. (V.) braziliensis, whereas a high cross-reaction ranging from 24.4% to 25% was observed with total crude promastigote antigens (PRO-ELISA). The ESA-blot of L. (L.) chagasi tested with non-visceral sera samples showed a cross-reaction with 8.8% of cases; most of these cases represented tegumentary leishmaniasis and only one acute chagasic case. These data lead us to recommend the use of ESA as an alternative antigen in VL diagnosis.

  9. http://www.esa.int/esaSC/Pr_21_2004_s_en.html

    NASA Astrophysics Data System (ADS)

    2004-09-01

    X-ray brightness map hi-res Size hi-res: 38 Kb Credits: ESA/ XMM-Newton/ Patrick Henry et al. X-ray brightness map This map shows "surface brightness" or how luminous the region is. The larger of the two galaxy clusters is brighter, shown here as a white and red spot. A second cluster resides about "2 o'clock" from this, shown by a batch of yellow surrounded by green. Luminosity is related to density, so the densest regions (cluster cores) are the brightest regions. The white color corresponds to regions of the highest surface brightness, followed by red, orange, yellow, green, blue and purple. High resolution version (JPG format) 38 Kb High resolution version (TIFF format) 525 Kb Temperature map Credits: NASA Artist’s impression of cosmic head on collision The event details what the scientists are calling the perfect cosmic storm: galaxy clusters that collided like two high-pressure weather fronts and created hurricane-like conditions, tossing galaxies far from their paths and churning shock waves of 100-million-degree gas through intergalactic space. The tiny dots in this artist's concept are galaxies containing thousand million of stars. Animated GIF version Temperature map hi-res Size hi-res: 57 Kb Credits: ESA/ XMM-Newton/ Patrick Henry et al. Temperature map This image shows the temperature of gas in and around the two merging galaxy clusters, based directly on X-ray data. The galaxies themselves are difficult to identify; the image highlights the hot ‘invisible’ gas between the clusters heated by shock waves. The white colour corresponds to regions of the highest temperature - million of degrees, hotter than the surface of the Sun - followed by red, orange, yellow and blue. High resolution version (JPG format) 57 Kb High resolution version (TIFF format) 819 Kb The event details what the scientists are calling the ‘perfect cosmic storm’: galaxy clusters that collided like two high-pressure weather fronts and created hurricane-like conditions

  10. Observation of confinement effects through liner and nonlinear absorption spectroscopy in cuprous oxide

    NASA Astrophysics Data System (ADS)

    Sekhar, H.; Rakesh Kumar, Y.; Narayana Rao, D.

    2015-02-01

    Cuprous oxide nano clusters, micro cubes and micro particles were successfully synthesized by reducing copper (II) salt with ascorbic acid in the presence of sodium hydroxide via a co-precipitation method. The X-ray diffraction studies revealed the formation of pure single phase cubic. Raman spectrum shows the inevitable presence of CuO on the surface of the Cu2O powders which may have an impact on the stability of the phase. Transmission electron microscopy (TEM) data revealed that the morphology evolves from nanoclusters to micro cubes and micro particles by increasing the concentration of NaOH. Linear optical measurements show that the absorption peak maximum shifts towards red with changing morphology from nano clusters to micro cubes and micro particles. The nonlinear optical properties were studied using open aperture Z-scan technique with 532 nm, 6 ns laser pulses. Samples exhibited saturable as well as reverse saturable absorption. The results show that the transition from SA to RSA is ascribed to excited-state absorption (ESA) induced by two-photon absorption (TPA) process. Due to confinement effects (enhanced band gap) we observed enhanced nonlinear absorption coefficient (βeff) in the case of nano-clusters compared to their micro-cubes and micro-particles.

  11. L(alpha)-induced two-photon absorption of visible light emitted from an O-type star by H2(+) ions located near the surface of the Stromgren sphere surrounding the star: A possible explanation for the diffuse interstellar absorption bands (DIDs)

    NASA Technical Reports Server (NTRS)

    Glownia, James H.; Sorokin, Peter P.

    1994-01-01

    In this paper, a new model is proposed to account for the DIB's (Diffuse Interstellar Bands). In this model, the DIB's result from a non-linear effect: resonantly-enhanced two-photon absorption of H(2+) ions located near the surface of the Stromgren sphere that surrounds an O- or B- type star. The strong light that is required to 'drive' the two-photon transition is provided by L(alpha) light emerging from the Stromgren sphere that bounds the H II region surrounding the star. A value of approximately 100 micro W/sq cm is estimated for the L(alpha) flux at the Stromgren radius, R(s), of a strong (O5) star. It is shown that a c.w. L(alpha) flux of this intensity should be sufficient to induce a few percent absorption for visible light radiated by the same star at a frequency (omega2) that completes an allowed two-photon transition, provided (1) the L(alpha) radiation happens to be nearly resonant with the frequency of a fully-allowed absorber transition that effectively represents the first step in the two-photon transition, and (2) an effective column density approximately 10(sup18)/sq cm of the absorber is present near the Stromgren sphere radius, R(sub s).

  12. A Comparison of ESA and NASA Space Debris Models

    NASA Astrophysics Data System (ADS)

    Hauptmann, S.

    1996-12-01

    NASA recently developed a new orbital debris environment model for spacecraft design and observations in low earth orbit. This model has been implemented at ESA/ESTEC in an application which is able to assess debris flux distributions according to target and impactor orbital parameters as well as the directional dependencies of the impactor fluxes. In this paper, the following three models are compared: the above mentioned NASA model, the ESA MASTER Analyst Application, developed under ESA/ESOC contract in 1995 and the current NASA space debris reference model, which was developed in 1989. The conceptual designs of the three models are discussed and their quantitative predictions are compared for various target orbit characteristics, including more detailed analysis of the orbits of ERS-1, LDEF and ISSA (International Space Station Alpha). It is shown in particular that considerable discrepancies of more than one order of magnitude exist between the predictions of the different models in the region of sub-mm sized particles as well as for diameters greater than 1cm. Refined predictions of the debris flux given by the different models taking into account the orientation of the surface are investigated in the case of LDEF and ISSA. For further information on ESA and NASA space debris modelling activities have a look at the following sites:

    • Space Debris Activities at ESOC
    • Modelling the Space Environment at ESTEC
    • UNO Office of Outer Space Affairs
    • NASA-JSC Space Science Branch

  13. Broadband transient absorption spectroscopy with 1- and 2-photon excitations: Relaxation paths and cross sections of a triphenylamine dye in solution

    SciTech Connect

    Moreno, J.; Dobryakov, A. L.; Hecht, S. E-mail: skovale@chemie.hu-berlin.de; Kovalenko, S. A. E-mail: skovale@chemie.hu-berlin.de; Ioffe, I. N.; Granovsky, A. A.

    2015-07-14

    1-photon (382 nm) and 2-photon (752 nm) excitations to the S{sub 1} state are applied to record and compare transient absorption spectra of a push-pull triphenylamine (TrP) dye in solution. After 1-photon excitation, ultrafast vibrational and structural molecular relaxations are detected on a 0.1 ps time scale in nonpolar hexane, while in polar acetonitrile, the spectral evolution is dominated by dipolar solvation. Upon 2-photon excitation, transient spectra in hexane reveal an unexpected growth of stimulated emission (SE) and excited-state absorption (ESA) bands. The behavior is explained by strong population transfer S{sub 1} → S{sub n} due to resonant absorption of a third pump photon. Subsequent S{sub n} → S{sub 1} internal conversion (with τ{sub 1} = 1 ps) prepares a very hot S{sub 1} state which cools down with τ{sub 2} = 13 ps. The pump pulse energy dependence proves the 2-photon origin of the bleach signal. At the same time, SE and ESA are strongly affected by higher-order pump absorptions that should be taken into account in nonlinear fluorescence applications. The 2-photon excitation cross sections σ{sup (2)} = 32 ⋅ 10{sup −50} cm{sup 4} s at 752 nm are evaluated from the bleach signal.

  14. Broadband transient absorption spectroscopy with 1- and 2-photon excitations: Relaxation paths and cross sections of a triphenylamine dye in solution.

    PubMed

    Moreno, J; Dobryakov, A L; Ioffe, I N; Granovsky, A A; Hecht, S; Kovalenko, S A

    2015-07-14

    1-photon (382 nm) and 2-photon (752 nm) excitations to the S1 state are applied to record and compare transient absorption spectra of a push-pull triphenylamine (TrP) dye in solution. After 1-photon excitation, ultrafast vibrational and structural molecular relaxations are detected on a 0.1 ps time scale in nonpolar hexane, while in polar acetonitrile, the spectral evolution is dominated by dipolar solvation. Upon 2-photon excitation, transient spectra in hexane reveal an unexpected growth of stimulated emission (SE) and excited-state absorption (ESA) bands. The behavior is explained by strong population transfer S1 → Sn due to resonant absorption of a third pump photon. Subsequent Sn → S1 internal conversion (with τ1 = 1 ps) prepares a very hot S1 state which cools down with τ2 = 13 ps. The pump pulse energy dependence proves the 2-photon origin of the bleach signal. At the same time, SE and ESA are strongly affected by higher-order pump absorptions that should be taken into account in nonlinear fluorescence applications. The 2-photon excitation cross sections σ(2) = 32 ⋅ 10(-50) cm(4) s at 752 nm are evaluated from the bleach signal.

  15. Aerosol retrieval experiments in the ESA Aerosol_cci project

    NASA Astrophysics Data System (ADS)

    Holzer-Popp, T.; de Leeuw, G.; Griesfeller, J.; Martynenko, D.; Klüser, L.; Bevan, S.; Davies, W.; Ducos, F.; Deuzé, J. L.; Graigner, R. G.; Heckel, A.; von Hoyningen-Hüne, W.; Kolmonen, P.; Litvinov, P.; North, P.; Poulsen, C. A.; Ramon, D.; Siddans, R.; Sogacheva, L.; Tanre, D.; Thomas, G. E.; Vountas, M.; Descloitres, J.; Griesfeller, J.; Kinne, S.; Schulz, M.; Pinnock, S.

    2013-08-01

    Within the ESA Climate Change Initiative (CCI) project Aerosol_cci (2010-2013), algorithms for the production of long-term total column aerosol optical depth (AOD) datasets from European Earth Observation sensors are developed. Starting with eight existing pre-cursor algorithms three analysis steps are conducted to improve and qualify the algorithms: (1) a series of experiments applied to one month of global data to understand several major sensitivities to assumptions needed due to the ill-posed nature of the underlying inversion problem, (2) a round robin exercise of "best" versions of each of these algorithms (defined using the step 1 outcome) applied to four months of global data to identify mature algorithms, and (3) a comprehensive validation exercise applied to one complete year of global data produced by the algorithms selected as mature based on the round robin exercise. The algorithms tested included four using AATSR, three using MERIS and one using PARASOL. This paper summarizes the first step. Three experiments were conducted to assess the potential impact of major assumptions in the various aerosol retrieval algorithms. In the first experiment a common set of four aerosol components was used to provide all algorithms with the same assumptions. The second experiment introduced an aerosol property climatology, derived from a combination of model and sun photometer observations, as a priori information in the retrievals on the occurrence of the common aerosol components. The third experiment assessed the impact of using a common nadir cloud mask for AATSR and MERIS algorithms in order to characterize the sensitivity to remaining cloud contamination in the retrievals against the baseline dataset versions. The impact of the algorithm changes was assessed for one month (September 2008) of data: qualitatively by inspection of monthly mean AOD maps and quantitatively by comparing daily gridded satellite data against daily averaged AERONET sun photometer

  16. Dual band metamaterial perfect absorber based on artificial dielectric "molecules".

    PubMed

    Liu, Xiaoming; Lan, Chuwen; Li, Bo; Zhao, Qian; Zhou, Ji

    2016-07-13

    Dual band metamaterial perfect absorbers with two absorption bands are highly desirable because of their potential application areas such as detectors, transceiver system, and spectroscopic imagers. However, most of these dual band metamaterial absorbers proposed were based on resonances of metal patterns. Here, we numerically and experimentally demonstrate a dual band metamaterial perfect absorber composed of artificial dielectric "molecules" with high symmetry. The artificial dielectric "molecule" consists of four "atoms" of two different sizes corresponding to two absorption bands with near unity absorptivity. Numerical and experimental absorptivity verify that the dual-band metamaterial absorber is polarization insensitive and can operate in wide-angle incidence.

  17. http://www.esa.int/esaSC/Pr_11_2004_s_en.html

    NASA Astrophysics Data System (ADS)

    2004-06-01

    surface of the moon and, most importantly, the presence of layers of dark material at the top of crater walls. "The imaging team is in hot debate at the moment on the interpretations of our findings," said Dr Carolyn Porco, Cassini imaging team leader at the Space Science Institute in Boulder, USA. "Based on our images, some of us are leaning towards the view that has been promoted recently, that Phoebe is probably ice-rich and may be an object originating in the outer solar system, more related to comets and Kuiper Belt objects than to asteroids." The high-resolution images of Phoebe show a world of dramatic landforms, with landslides and linear structures such as grooves, ridges and chains of pits. Craters are ubiquitous, with many smaller than one kilometre. "This means, besides the big ones, lots of projectiles smaller than 100 metres must have hit Phoebe," said Prof. Gerhard Neukum, Freie Universitaet Berlin, Germany, and a member of the imaging team. Whether these projectiles came from outside or within the Saturn system is debatable. There is a suspicion that Phoebe, the largest of Saturn's outer moons, might be parent to the other, much smaller retrograde outer moons that orbit Saturn. They could have resulted from the impact ejecta that formed the many craters on Phoebe. Besides these stunning images, the instruments on board Cassini collected a wealth of other data, which will allow scientists to study the surface structures, determine the mass and composition of Phoebe and create a global map of it. "If these additional data confirm that Phoebe is mostly ice, covered by layers of dust, this may well mean that we are looking at a 'leftover' from the formation of the Solar System about 4600 million years ago," said Dr Jean-Pierre Lebreton, ESA Huygens Project Scientist. Phoebe might indeed be an icy wanderer from the distant outer reaches of the Solar System, which, like a comet, was dislodged from the Kuiper Belt and captured by Saturn when the planet was

  18. Demonstrating xLuna on ESA EXOMADER Rover

    NASA Astrophysics Data System (ADS)

    Braga, P.

    2012-01-01

    In this article we present xLuna [1] and its successful demonstration on the ESA EXOMArs DEmonstration Rover (EXOMADER) [2]. xLuna is a Linux-specific hypervisor extension for RTEMS, a Real-time Executive already used on ESA missions. On xLuna, RTEMS runs natively and directly on top of the hardware providing all its native services to real- time control applications. On top of the hypervisor runs a Linux kernel para-virtualised specifically for the system that provides all the well known POSIX based services and an endless set of software libraries to payload applications. On the demonstration, the complete navigation software of the rover (with stereo image processing and path processing) that was being tested ran on xLuna's Linux subsystem, while the RTEMS components were running control tasks. Due to impossibilities of integration, the RTEMS tasks running were simulated. The control was performed by existing HW.

  19. Joint NASA-ESA Outer Planet Mission study overview

    NASA Astrophysics Data System (ADS)

    Lebreton, J.-P.; Niebur, C.; Cutts, J.; Falkner, P.; Greeley, R.; Lunine, J.; Blanc, M.; Coustenis, A.; Pappalardo, R.; Matson, D.; Clark, K.; Reh, K.; Stankov, A.; Erd, C.; Beauchamp, P.

    2009-04-01

    In 2008, ESA and NASA performed joint studies of two highly capable scientific missions to the outer planets: the Europa Jupiter System Mission (EJSM) and the Titan Saturn System Mission (TSSM). Joint Science Definition Teams (JSDTs) were formed with U.S. and European membership to guide study activities that were conducted collaboratively by engineering teams working on both sides of the Atlantic. EJSM comprises the Jupiter Europa Orbiter (JEO) that would be provided by NASA and the Jupiter Ganymede Orbiter (JGO) that would be provided by ESA. Both spacecraft would be launched independently in 2020, and arrive 6 years later for a 3-4 year mission within the Jupiter System. Both orbiters would explore Jupiter's system on trajectories that include flybys of Io (JEO only), Europa (JEO only), Ganymede and Callisto. The operation of JEO would culminate in orbit around Europa while that of JGO would culminate in orbit around Ganymede. Synergistic and coordinated observations would be planned. The Titan Saturn System Mission (TSSM) comprises a Titan Orbiter provided by NASA that would carry two Titan in situ elements provided by ESA: the montgolfière and the lake lander. The mission would launch in 2020 and arrive 9 years later for a 4-year duration in the Saturn system. Following delivery of the ESA in situ elements to Titan, the Titan Orbiter would explore the Saturn system via a 2-year tour that includes Enceladus and Titan flybys. The montgolfière would last at least 6-12 months at Titan and the lake lander 8-10 hours. Following the Saturn system tour, the Titan Orbiter would culminate in a ~2-year orbit around Titan. Synergistic and coordinated observations would be planned between the orbiter and in situ elements. The ESA contribution to this joint endeavor will be implemented as the first Cosmic Vision Large-class (L1) mission; the NASA contribution will be implemented as the Outer Planet Flagship Mission. The contribution to each mission is being reviewed and

  20. ESA's X-ray space observatory XMM takes first pictures

    NASA Astrophysics Data System (ADS)

    2000-02-01

    Under the aegis of Prof. Roger Bonnet, ESA Director of Science, the mission's Principal Investigators will be presenting these spectacular first images at a press conference to be held on 9 February at the ESA Vilspa facility at Villafranca/Madrid in Spain, where the XMM Science Operations Centre is located. The event will also be the occasion for several major announcements concerning the XMM mission. In particular Professor Bonnet will launch the third XMM competition "Stargazing" - previously announced in September 1999. This will address European youngsters, 16 to 18 years old, who will be offered the unique opportunity of winning observing time using the X-ray telescope. Commissioning phase starts After a successful launch from Kourou on Ariane 504 on 10 December 1999, XMM was brought to its final operational orbit in the following week. The telescope doors on the X-ray Mirror Modules and on the Optical Monitor telescope were opened on 17/18 December. The Radiation Monitor was activated on 19 December and the spacecraft was put into a quiet mode over the Christmas and New Year period. The mission's scientific data is being received, processed and dispatched to astronomers by the XMM Science Operations Centre in Villafranca. Operations with the spacecraft restarted there on 4 January when, as part of the commissioning phase, all the science payloads were switched on one after the other for initial verifications. By the week of 17 January functional tests had begun on the Optical Monitor, the EPIC pn, the two EPIC MOS and the two RGS instruments. The internal doors of the EPIC cameras were opened whilst keeping the camera filter wheels closed. Astounding first images After a series of engineering exposures, all three EPIC cameras were used in turn, between 19-24 January, to take several views of two different extragalactic regions of the Universe. These views, featuring a variety of extended and X-ray point sources, were chosen to demonstrate the full

  1. ESA SMART-1 mission: review of results and legacy 10 years after launch

    NASA Astrophysics Data System (ADS)

    Foing, Bernard

    2014-05-01

    We review ESA's SMART-1 highlights and legacy 10 years after launch. The SMART-1 mission to the Moon achieved record firsts such as: 1) first Small Mission for Advanced Research and Technology; with spacecraft built and integrated in 2.5 years and launched 3.5 years after mission approval; 2) first mission leaving the Earth orbit using solar power alone with demonstration for future deep space missions such as BepiColombo; 3) most fuel effective mission (60 litres of Xenon) and longest travel (13 month) to the Moon!; 4) first ESA mission reaching the Moon and first European views of lunar poles; 5) first European demonstration of a wide range of new technologies: Li-Ion modular battery, deep-space communications in X- and Ka-bands, and autonomous positioning for navigation; 6) first lunar demonstration of an infrared spectrometer and of a Swept Charge Detector Lunar X-ray fluorescence spectrometer ; 7) first ESA mission with opportunity for lunar science, elemental geochemistry, surface mineralogy mapping, surface geology and precursor studies for exploration; 8) first controlled impact landing on the Moon with real time observations campaign; 9) first mission supporting goals of the ILEWG/COSPAR International Lunar Exploration Working Group in technical and scientific exchange, international collaboration, public and youth engagement; 10) first mission preparing the ground for ESA collaboration in Chandrayaan-1, Chang'E1-2-3 and near-future landers, sample return and human lunar missions. The SMART-1 technology legacy is applicable to geostationary satellites and deep space missions using solar electric propulsion. The SMART-1 archive observations have been used to support scientific research and prepare subsequent lunar missions and exploration. Most recent SMART-1 results are relevant to topics on: 1) the study of properties of the lunar dust, 2) impact craters and ejecta, 3) the study of illumination, 4) observations and science from the Moon, 5) support to

  2. ESA SMART-1 mission: results and lessons for future lunar exploration

    NASA Astrophysics Data System (ADS)

    Foing, Bernard H.

    We review ESA’s SMART-1 highlights and legacy 10 years after launch. We discuss lessons for future lunar exploration and upcoming missions. The SMART-1 mission to the Moon achieved record firsts such as: 1) first Small Mission for Advanced Research and Technology; with spacecraft built and integrated in 2.5 years and launched 3.5 years after mission approval; 2) first mission leaving the Earth orbit using solar power alone with demonstration for future deep space missions such as BepiColombo; 3) most fuel effective mission (60 litres of Xenon) and longest travel (13 month) to the Moon!; 4) first ESA mission reaching the Moon and first European views of lunar poles; 5) first European demonstration of a wide range of new technologies: Li-Ion modular battery, deep-space communications in X- and Ka-bands, and autonomous positioning for navigation; 6) first lunar demonstration of an infrared spectrometer and of a Swept Charge Detector Lunar X-ray fluorescence spectrometer ; 7) first ESA mission with opportunity for lunar science, elemental geochemistry, surface mineralogy mapping, surface geology and precursor studies for exploration; 8) first controlled impact landing on the Moon with real time observations campaign; 9) first mission supporting goals of the ILEWG/COSPAR International Lunar Exploration Working Group in technical and scientific exchange, international collaboration, public and youth engagement; 10) first mission preparing the ground for ESA collaboration in Chandrayaan-1, Chang’ E1-2-3 and near-future landers, sample return and human lunar missions. The SMART-1 technology legacy is applicable to application geostationary missions and deep space missions using solar electric propulsion. The SMART-1 archive observations have been used to support scientific research and prepare subsequent lunar missions. Most recent SMART-1 results are relevant to topics on: 1) the study of properties of the lunar dust, 2) impact craters and ejecta, 3) the study of

  3. ESA space spin-offs benefits for the health sector

    NASA Astrophysics Data System (ADS)

    Szalai, Bianca; Detsis, Emmanouil; Peeters, Walter

    2012-11-01

    Humanity will be faced with an important number of future challenges, including an expansion of the lifespan, a considerable increase of the population (estimated 9 billion by 2050) and a depletion of resources. These factors could trigger an increase of chronic diseases and various other health concerns that would bear a heavy weight on finances worldwide. Scientific advances can play an important role in solving a number of these problems, space technology; in general, can propose a panoply of possible solutions and applications that can make life on Earth easier and better for everyone. Satellites, Earth Observation, the International Space Station (ISS) and the European Space Agency (ESA) may not be the first tools that come to mind when thinking of improving health, yet there are many ways in which ESA and its programmes contribute to the health care arena. The research focuses on quantifying two ESA spin-offs to provide an initial view on how space can contribute to worldwide health. This quantification is part of the present strategy not only to show macroeconomic return factors for space in general, but also to identify and describe samples of 'best practice' type of examples close to the general public's interest. For each of the 'best practices' the methodology takes into account the cost of the space hardware/software, a number of tangible and intangible benefits, as well as some logical assumptions in order to determine the potential overall returns. Some of the hindering factors for a precise quantification are also highlighted. In conclusion, the study recommends a way in which ESA's spin-offs can be taken into account early on in the development process of space programmes in order to generate higher awareness with the general public and also to provide measurable returns.

  4. NASA/ESA CV-990 Spacelab Simulation (ASSESS 2)

    NASA Technical Reports Server (NTRS)

    Mulholland, D. R.; Androes, G. M.; Reeves, J. F.

    1978-01-01

    To test the validity of the ARC approach to Spacelab, several missions simulating aspects of Spacelab operations have been conducted as part of the ASSESS Program. Each mission was designed to evaluate potential Shuttle/Spacelab concepts in increasing detail. For this mission, emphasis was placed on development and exercise of management techniques planned for Spacelab using management participants from NASA and ESA who have responsibilities for Spacelab 1 which will be launched in 1980.

  5. ESRO/ESA and Denmark. Participation by research and industry

    NASA Astrophysics Data System (ADS)

    Gudmandsen, Preben

    2003-09-01

    These notes are prepared to give an impression of considerations and activities in Denmark related to ESRO and ESA, roughly in the period 1964 to 1990. In a number of chapters we consider early space-related research in Denmark, the initial phase of the ESRO era and the following period, including the phase of transition from ESRO to ESA when Denmark seriously considered leaving the space co-operation. A chapter gives examples of activities in the ESA era within space science and astronomy, Earth Observation and microgravity, followed by a final one dealing with the national management of optional programmes and the involvement by industry. In drafting the notes we have taken advantage of the work carried out in the Introductory Studies carried out to secure and place in order the archives of the Danish Space Research Advisory Committee. In this connection excerpts of individual documents (mostly minutes of meetings, letters and reports) were taken. To a great extent they form the basis for many of the points made in the notes.

  6. SNAP (Sentinel Application Platform) and the ESA Sentinel 3 Toolbox

    NASA Astrophysics Data System (ADS)

    Zuhlke, Marco; Fomferra, Norman; Brockmann, Carsten; Peters, Marco; Veci, Luis; Malik, Julien; Regner, Peter

    2015-12-01

    ESA is developing three new free open source Toolboxes for the scientific exploitation of the Sentinel-1, Sentinel-2 and Sentinel-3 missions. The Toolboxes are based on a common software platform, namely the Sentinel Application Platform (SNAP). SNAP is an evolution of the proven ESA BEAM/NEST architecture inheriting all current BEAM and NEST functionality including multi-mission support for SAR and optical missions to support ESA and third party missions for years to come. The Sentinel-3 Toolbox includes generic function for visualisation and analysis of Sentinel-3 OLCI and SLSTR Level 1 and Level 2 data, as well as specific processing tools such as cloud screening, water constituent retrieval and SST retrieval. The Toolbox will put emphasis on access to remote in-situ databases such as Felyx or MERMAID, and exploitation of the data-uncertainty information which is included in the Sentinel-3 data products. New image classification, segmentation and filtering methods, as well as interoperability with the ORFEO Toolbox and the GDAL libraries will be additional new tools. New challenges stemming from Sentinel-3 sensors, such as raster data in different resolutions within a single dataset, will be supported gracefully. The development of SNAP and the Sentinel Toolboxes is funded through the “Scientific Exploitation of Operational Missions (SEOM)” programme, a new programme element of ESA’s fourth period of the Earth Observation Envelope Programme (2013-2017).

  7. ESA and the arts: A programme in the making

    NASA Astrophysics Data System (ADS)

    Raitt, David

    2007-01-01

    Space exploration is arguably the greatest voyage of discovery ever undertaken and just as artists have traditionally accompanied the great ocean and land voyages of the past, so artists have been and are at the forefront of space voyages of the future. Increasingly, the European Space Agency (ESA) is being asked to support or participate in artistic and cultural events, largely as a result of its study into science fiction literature and artwork. The paper first gives an overview of the relationship between space and art by discussing art that has been sent into space, orbital sculptures, art on Earth seen from space, and performance art and dance in zero gravity. The paper then provides an update on ESA's involvement in some activities in this domain including the organization of science fiction and space art exhibitions, workshops and competitions, and a recently launched study into how ESA might use the European components of the International Space Station for artistic and cultural events to enable the public to better share the human experience of space missions and interact with the sights and sounds of space.

  8. The ESA/NASA ExoMars Trace Gas Orbiter

    NASA Astrophysics Data System (ADS)

    Witasse, O.; Allen, M.

    2011-10-01

    The European Space Agency (ESA), in close cooperation with NASA, has established the ExoMars Programme to investigate the Martian environment and habitability, and to demonstrate new technologies paving the way for a future sample return mission. Within this programme, the first proposed mission consists of an ESA spacecraft that will carry an Entry, Descent and Landing Demonstrator. It will be launched in January 2016 with a NASA supplied Atlas V rocket. The scientific goals of the mission are to study Martian atmospheric trace gases, with a focus on chemical species that could reflect the existence of extant active processes (geological or biological). More specifically, the mission will detect the chemical compounds, characterise their spatial and temporal variability and localise their sources on the surface. Five instruments (see table) will be accommodated on the orbiter to achieve these objectives. Following an aerobraking phase, the scientific mission is expected to begin in spring 2017 for a period of at least one Martian year. The presentation will focus primarily on the description of the mission, responsibilities between ESA and NASA, payload, timelines and milestones.

  9. ESA Intermediate Experimental Vehicle. Independent Aerothermodynamic Characterization And Aerodatabase Development

    NASA Astrophysics Data System (ADS)

    Rufolo, Giuseppe C.; Di Benedetto, Sara; Walpot, Louis; Roncioni, Pietro; Marini, Marco

    2011-05-01

    In the frame of the Intermediate eXperimental Vehicle (IXV) project, the European Space Agency (ESA) is coordinating a series of technical assistance activities aimed at verifying and supporting the IXV industrial design and development process. The technical assistance is operated with the support of the Italian Space Agency (ASI), by means of the Italian Aerospace Research Center (CIRA), and the European Space Research and Technology Centre (ESTEC) under the super visioning and coordination of ESA IXV team. One of the purposes of the activity is to develop an independent capability for the assessment and verification of the industrial results with respect to the aerothermodynamic characterization of the IXV vehicle. To this aim CIRA is developing and independent AeroThermodynamics DataBase (ATDB), intended as a tool generating in output the time histories of local quantities (heat flux, pressure, skin friction) for each point of the IXV vehicle and for each trajectory (in a pre-defined envelope), together with an uncertainties model. The reference Computational Fluid Dynamics (CFD) solutions needed for the development of the tool have been provided by ESA-ESTEC (with the CFD code LORE) and CIRA (with the CFD code H3NS).

  10. SMART-1 Technology and Science Experiments in Preparation of Future Missions and ESA Cornerstones

    NASA Astrophysics Data System (ADS)

    Marini, A. E.; Racca, G. D.; Foing, B. H.; SMART-1 Project

    1999-12-01

    SMART-1 is the first ESA Small Mission for Advanced Research in Technology, aimed at the demonstration of enabling technologies for future scientific missions. SMART-1's prime technology objective is the demonstration of the solar primary electric propulsion, a key for future interplanetary missions. SMART-1 will use a Stationary Plasma Thruster engine, cruising 15 months to capture a Moon polar orbit. A gallery of images of the spacecraft is available at the web site: http://www.estec.esa.nl/spdwww/smart1/html/11742.html SMART-1 payload aims at monitoring the electric propulsion and its spacecraft environment and to test novel instrument technologies. The Diagnostic Instruments include SPEDE, a spacecraft potential plasma and charged particles detector, to characterise both spacecraft and planetary environment, together with EPDP, a suite of sensors monitoring secondary thrust-ions, charging and deposition effects. Innovative spacecraft technologies will be tested on SMART-1 : Lithium batteries and KATE, an experimental X/Ka-band deep-space transponder, to support radio-science, to monitor the accelerations of the electric propulsion and to test turbo-code technique, enhancing the return of scientific data. The scientific instruments for imaging and spectrometry are: \\begin{itemize} D-CIXS, a compact X-ray spectrometer based on novel SCD detectors and micro-structure optics, to observe X-ray celectial objects and to perform lunar chemistry measurements. SIR, a miniaturised quasi-monolithic point-spectrometer, operating in the Near-IR (0.9 ÷ 2.4 micron), to survey the lunar crust in previously uncovered optical regions. AMIE, a miniature camera based on 3-D integrated electronics, imaging the Moon, and other bodies and supporting LASER-LINK and RSIS. RSIS and LASER-LINK are investigations performed with the SMART-1 Payload: \\begin{itemize} RSIS: A radio-science Experiment to validate in-orbit determination of the libration of the celestial target, based on high

  11. ESA astronauts assigned to Tethered Satellite System mission - STS-75

    NASA Astrophysics Data System (ADS)

    1995-01-01

    The TSS project is a joint NASA/ASI (Italian Space Agency) effort. On STS-75, the five-foot diameter (1.6 metre) Italia built satellite is scheduled to be deployed on the end of a 1 mile long (20 kilometre) conductive tether to study the electrodynamic effects of moving such a tether through the Earth's magnetic field. The experiment will also test techniques for managing the tethered spacecraft at great distances. Throughout the 13-day flight, additional experiments housed in the orbiter's payload bay will give scientists access to s for microgravity and fundamental science investigations. The USMP is designed to provide the foundation for advanced scientific investigations similar to those planned aboard the International Space Station. Claude Nicollier, who is Swiss, was selected by ESA in 1978 as one of three European payload specialists to train for the SPACELAB-1 mission. He was a mission specialist on STS- 46 (31 July-8 August 1992), during which the crew members deployed ESA's retrievable science platform (EURECA) and conducted the first TSS test flight. A few months after his return from this mission Claude Nicollier was selected as mission specialist for STS-61 (2-13 December 1993). He contributed considerably to the complete success of the Hubble Space Telescope repair and refurbishment mission and in particular the replacement of the ESA-provided solar arrays. Maurizio Cheli, an Italian, was selected by ESA in May 1992 along with five other young candidates to expand the corps of ESA astronauts. He has been in Houston since mid-1992 and has qualified as mission specialist at NASA's Johnson Space Center there. STS-75 will be his first Shuttle flight. Marine Corps Lt. Col. Andrew M. Allen will command Space Shuttle Columbia's STS-75 mission. Joining Allen are Air Force Major Scott J. Horowitz, pilot; payload commander Franklin R. Chang-Diaz, Ph. D; Italian Space Agency (ASI) TSS payload specialist Umberto Guidoni, Ph.D; mission specialist Jeffrey A

  12. The ESA Scientific Exploitation of Operational Missions element, first results

    NASA Astrophysics Data System (ADS)

    Desnos, Yves-Louis; Regner, Peter; Delwart, Steven; Benveniste, Jerome; Engdahl, Marcus; Mathieu, Pierre-Philippe; Gascon, Ferran; Donlon, Craig; Davidson, Malcolm; Pinnock, Simon; Foumelis, Michael; Ramoino, Fabrizio

    2016-04-01

    SEOM is a program element within the fourth period (2013-2017) of ESA's Earth Observation Envelope Programme (http://seom.esa.int/). The prime objective is to federate, support and expand the international research community that the ERS, ENVISAT and the Envelope programmes have built up over the last 25 years. It aims to further strengthen the leadership of the European Earth Observation research community by enabling them to extensively exploit future European operational EO missions. SEOM will enable the science community to address new scientific research that are opened by free and open access to data from operational EO missions. Based on community-wide recommendations for actions on key research issues, gathered through a series of international thematic workshops and scientific user consultation meetings, a work plan is established and is approved every year by ESA Members States. During 2015 SEOM, Science users consultation workshops have been organized for Sentinel1/3/5P ( Fringe, S3 Symposium and Atmospheric science respectively) , new R&D studies for scientific exploitation of the Sentinels have been launched ( S3 for Science SAR Altimetry and Ocean Color , S2 for Science,) , open-source multi-mission scientific toolboxes have been launched (in particular the SNAP/S1-2-3 Toolbox). In addition two advanced international training courses have been organized in Europe to exploit the new S1-A and S2-A data for Land and Ocean remote sensing (over 120 participants from 25 countries) as well as activities for promoting the first scientific results ( e.g. Chili Earthquake) . In addition the First EO Open Science 2.0 was organised at ESA in October 2015 with 225 participants from 31 countries bringing together young EO scientists and data scientists. During the conference precursor activities in EO Open Science and Innovation were presented, while developing a Roadmap preparing for future ESA scientific exploitation activities. Within the conference, the first

  13. The Software Architecture of the Upgraded ESA DRAMA Software Suite

    NASA Astrophysics Data System (ADS)

    Kebschull, Christopher; Flegel, Sven; Gelhaus, Johannes; Mockel, Marek; Braun, Vitali; Radtke, Jonas; Wiedemann, Carsten; Vorsmann, Peter; Sanchez-Ortiz, Noelia; Krag, Holger

    2013-08-01

    In the beginnings of man's space flight activities there was the belief that space is so big that everybody could use it without any repercussions. However during the last six decades the increasing use of Earth's orbits has lead to a rapid growth in the space debris environment, which has a big influence on current and future space missions. For this reason ESA issued the "Requirements on Space Debris Mitigation for ESA Projects" [1] in 2008, which apply to all ESA missions henceforth. The DRAMA (Debris Risk Assessment and Mitigation Analysis) software suite had been developed to support the planning of space missions to comply with these requirements. During the last year the DRAMA software suite has been upgraded under ESA contract by TUBS and DEIMOS to include additional tools and increase the performance of existing ones. This paper describes the overall software architecture of the ESA DRAMA software suite. Specifically the new graphical user interface, which manages the five main tools ARES (Assessment of Risk Event Statistics), MIDAS (MASTER-based Impact Flux and Damage Assessment Software), OSCAR (Orbital Spacecraft Active Removal), CROC (Cross Section of Complex Bodies) and SARA (Re-entry Survival and Risk Analysis) is being discussed. The advancements are highlighted as well as the challenges that arise from the integration of the five tool interfaces. A framework had been developed at the ILR and was used for MASTER-2009 and PROOF-2009. The Java based GUI framework, enables the cross-platform deployment, and its underlying model-view-presenter (MVP) software pattern, meet strict design requirements necessary to ensure a robust and reliable method of operation in an environment where the GUI is separated from the processing back-end. While the GUI framework evolved with each project, allowing an increasing degree of integration of services like validators for input fields, it has also increased in complexity. The paper will conclude with an outlook on

  14. 78 FR 18585 - FIFRA Pesticide Registration Review and ESA Consultation Processes; Stakeholder Input; Notice of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-27

    ... AGENCY FIFRA Pesticide Registration Review and ESA Consultation Processes; Stakeholder Input; Notice of... pesticide registrations under the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) and associated... facilitate ESA pesticide consultations and coordination across these Federal agencies, and calls for...

  15. EsaD, a secretion factor for the Ess pathway in Staphylococcus aureus.

    PubMed

    Anderson, Mark; Chen, Yi-Hsing; Butler, Emily K; Missiakas, Dominique M

    2011-04-01

    Staphylococcus aureus encodes the Sec-independent Ess secretion pathway, an ortholog of mycobacterial T7 secretion systems which is required for the virulence of this Gram-positive microbe. The Ess (ESX secretion) pathway was previously defined as a genomic cluster of eight genes, esxA, esaA, essA, essB, esaB, essC, esaC, and esxB. essABC encode membrane proteins involved in the stable expression of esxA, esxB, and esaC, genes specifying three secreted polypeptide substrates. esaB, which encodes a small cytoplasmic protein, represses the synthesis of EsaC but not that of EsxA and EsxB. Here we investigated a hitherto uncharacterized gene, esaD, located downstream of esxB. Expression of esaD is activated by mutations in esaB and essB. EsaD, the 617-amino-acid product of esaD, is positioned in the membrane and is also accessible to EsaD-specific antibodies on the bacterial surface. S. aureus mutants lacking esaD are defective in the secretion of EsxA. Following intravenous inoculation of mice, S. aureus esaD mutants generate fewer abscesses with a reduced bacterial load compared to wild-type parent strain Newman. The chromosomes of Listeria and Bacillus species with Ess pathways also harbor esaD homologues downstream of esxB, suggesting that the contributory role of EsaD in Ess secretion may be shared among Gram-positive pathogens.

  16. Band heterotopia.

    PubMed

    Alam, M S; Naila, N

    2010-01-01

    Band heterotopias are one of the rarest groups of congenital disorder that result in variable degree of structural abnormality of brain parenchyma. Band of heterotopic neurons result from a congenital or acquired deficiency of the neuronal migration. MRI is the examination of choice for demonstrating these abnormalities because of the superb gray vs. white matter differentiation, detail of cortical anatomy and ease of multiplanar imaging. We report a case of band heterotopia that showed a bilateral band of gray matter in deep white matter best demonstrated on T2 Wt. and FLAIR images.

  17. ESA research and development activity on SSA-NEO preliminary definition

    NASA Astrophysics Data System (ADS)

    Franco, R.

    2010-10-01

    The paper gives an account of goals, prospects, and planning of the first ESA research associated with definition of the SSA-NEO segment and puts it in the context of ESA system engineering practices of ESA (as defined in ESA’s ECSS standards).

  18. Green light for deployment of ESA's Mars Express radar

    NASA Astrophysics Data System (ADS)

    2005-02-01

    ESA's decision to deploy MARSIS follows eight months of intensive computer simulations and technical investigations on both sides of the Atlantic. These were to assess possible harmful boom configurations during deployment and to determine any effects on the spacecraft and its scientific instruments. The three radar booms of MARSIS were initially to have been deployed in April 2004, towards the end of the Mars Express instrument commissioning phase. They consist of a pair of 20-metre hollow cylinders, each 2.5 centimetres in diameter, and a 7-metre boom. No satisfactory ground test of deployment in flight conditions was possible, so that verification of the booms' performance had to rely on computer simulation. Just prior to their scheduled release, improved computer simulations carried out by the manufacturer, Astro Aerospace (California), revealed the possibility of a whiplash effect before they locked in their final outstretched positions, so that they might hit the spacecraft. Following advice from NASA’s Jet Propulsion Laboratory (JPL), which contributed the boom system to the Italian-led MARSIS radar instrument, and the Mars Express science team, ESA put an immediate hold on deployment until a complete understanding of the dynamics was obtained. JPL led a comprehensive investigation, including simulations, theoretical studies and tests on representative booms, the latter to assess potential aging of the boom material. European experts, from ESA and the former spacecraft prime contractor, Astrium SAS, France, worked closely with JPL throughout the entire investigation. An independent engineering review board, composed of ESA and industry experts, met in January to evaluate the findings and advise on ‘if and when’ to proceed with deployment. The ESA review board, at its final meeting on 25 January, recommended deployment of the MARSIS booms. The rationale for the decision was based on the results of the analyses, which showed the possible impact scenarios

  19. The ESA Scientific Exploitation of Operational Missions element

    NASA Astrophysics Data System (ADS)

    Desnos, Yves-Louis; Regner, Peter; Delwart, Steven; Benveniste, Jerome; Engdahl, Marcus; Zehner, Claus; Mathieu, Pierre-Philippe; Bojkov, Bojan; Gascon, Ferran; Donlon, Craig; Davidson, Malcolm; Goryl, Philippe; Pinnock, Simon

    2015-04-01

    SEOM is a program element within the fourth period (2013-2017) of ESA's Earth Observation Envelope Programme (http://seom.esa.int/). The prime objective is to federate, support and expand the international research community that the ERS,ENVISAT and the Envelope programmes have built up over the last 25 years. It aims to further strengthen the leadership of the European Earth Observation research community by enabling them to extensively exploit future European operational EO missions. SEOM will enable the science community to address new scientific research that are opened by free and open access to data from operational EO missions. Based on community-wide recommendations for actions on key research issues, gathered through a series of international thematic workshops and scientific user consultation meetings, a work plan has been established and is approved every year by ESA Members States. The 2015 SEOM work plan is covering the organisation of three Science users consultation workshops for Sentinel1/3/5P , the launch of new R&D studies for scientific exploitation of the Sentinels, the development of open-source multi-mission scientific toolboxes, the organisation of advanced international training courses, summer schools and educational materials, as well as activities for promoting the scientific use of EO data. The first SEOM projects have been tendered since 2013 including the development of Sentinel toolboxes, advanced INSAR algorithms for Sentinel-1 TOPS data exploitation, Improved Atmospheric Spectroscopic data-base (IAS), as well as grouped studies for Sentinel-1, -2, and -3 land and ocean applications and studies for exploiting the synergy between the Sentinels. The status and first results from these SEOM projects will be presented and an outlook for upcoming SEOM studies will be given.

  20. ESA SSA Space Weather Services Supporting Space Surveillance and Tracking

    NASA Astrophysics Data System (ADS)

    Luntama, Juha-Pekka; Glover, Alexi; Hilgers, Alain; Fletcher, Emmet

    2012-07-01

    ESA Space Situational Awareness (SSA) Preparatory Programme was started in 2009. The objective of the programme is to support the European independent utilisation of and access to space research or services. This will be performed through providing timely and quality data, information, services and knowledge regarding the environment, the threats and the sustainable exploitation of the outer space surrounding the planet Earth. SSA serves the implementation of the strategic missions of the European Space Policy based on the peaceful uses of the outer space by all states, by supporting the autonomous capacity to securely and safely operate the critical European space infrastructures. The Space Weather (SWE) Segment of the SSA will provide user services related to the monitoring of the Sun, the solar wind, the radiation belts, the magnetosphere and the ionosphere. These services will include near real time information and forecasts about the characteristics of the space environment and predictions of space weather impacts on sensitive spaceborne and ground based infrastructure. The SSA SWE system will also include establishment of a permanent database for analysis, model development and scientific research. These services are will support a wide variety of user domains including spacecraft designers, spacecraft operators, human space flights, users and operators of transionospheric radio links, and space weather research community. The precursor SWE services to be established starting in 2010. This presentation provides an overview of the ESA SSA SWE services focused on supporting the Space Surveillance and Tracking users. This services include estimates of the atmospheric drag and archive and forecasts of the geomagnetic and solar indices. In addition, the SSA SWE system will provide nowcasts of the ionospheric group delay to support mitigation of the ionospheric impact on radar signals. The paper will discuss the user requirements for the services, the data

  1. ESA takes part in Earth observation and space science experiments on board the Space Shuttle

    NASA Astrophysics Data System (ADS)

    1993-03-01

    interesting phenomena show up. The third European instrument, called MAS (Millimeter Wave Atmospheric Sounder) will be measuring the absorption spectra of water vapour and trace gases in the upper atmosphere. The measurement programme includes most notably ozone and chlorine monoxide, which plays an important role in the ozone cycle. MAS was developed under the responsibility of Dr. Gerd Hartmann of the Max-Planck- Institute fuer Aeronomy, Lindau, Germany. The complex space-to-ground communications links and the tools to control the instruments from the laboratories in Europe have been designed to be as flexible and user-friendly as possible. The series of Atlas missions is enabling ESA to gain valuable experience for the future utilisation of its Columbus Attached Laboratory; its science results are at the same time a contribution to today's advances in space science and environmental research, complementing a number of dedicated ESA satellites currently under development, such as SOHO, ERS-2 and ENVISAT-1. Note to Editors : At the invitation of the Belgian Minister for Science Policy a press conference will be held on 22 March 1993 at 16.00 hours at the Belgian Royal Meteorological Institute in Brussels (IRMB). The press conference will be followed by the inauguration of the Space Remote Operations Centre, from where the telescience operations for the ATLAS-2 mission will be carried out. Apart from the Minister, those participating will include: Dirk Frimout, Belgian astronaut and ESA staff member Dominique Crommelynck, IRMB, Principal Investigator for SOLCON Gerard Thuillier, CNRS France, Principal Investigator for SOLSPEC Further information can be obtained from the Belgian Science Policy Office, Mrs. M.C. Limbourg or Mr. J. Bernard : Tel : +32.2.238.34.11 - Fax : +32.2.230.59.12

  2. Happy families - cutting the cost of ESA Mission Ground Software

    NASA Astrophysics Data System (ADS)

    Merri, Mario; Ercolani, Alessandro; Guerrucci, Damiano; Reggestad, Vemund; Verrier, David; Emanuelli, Pier Paolo; Ferri, Paolo

    2007-05-01

    In recent years, ESA has adopted a new approach to reduce cost and risk in the development and operation of ground software. The "mission family" concept is the basis for cost-effective mission control systems for monitoring and controlling spacecraft, and operational simulators for testing and training. This concept is complemented by exploiting reusable software using a "delta" approach. Since families of missions have lifetimes much longer than the individual projects, the challenges of evolving ground software and hardware platforms over ten or more years must be met.

  3. Aristoteles - An ESA mission to study the earth's gravity field

    NASA Astrophysics Data System (ADS)

    Lambeck, K.

    In preparing for its first Solid-Earth Program, ESA has studied a satellite concept for a mission dedicated to the precise determination of the earth's geopotential (gravitational and magnetic) fields. Data from such a mission are expected to make substantial contributions to a number of research and applications fields in solid-earth geophysics, oceanography and global-change monitoring. The impact of a high-resolution gravity-field mission on studies of the various earth-science problems is assessed. The current state of our knowledge in this area is discussed and the ability of low-orbit satellite gradiometry to contribute to their solution is demonstrated.

  4. The first Spacelab payload - A joint NASA/ESA venture

    NASA Technical Reports Server (NTRS)

    Kennedy, R.; Pace, R.; Collet, J.; Sanfourche, J. P.

    1977-01-01

    Planning for the 1980 qualification flight of Spacelab, which will involve a long module and one pallet, is discussed. The mission will employ two payload specialists, one sponsored by NASA and the other by ESA. Management of the Spacelab mission functions, including definition and execution of the on-board experiments, development of the experimental hardware and training of the payload specialists, is considered; studies proposed in the areas of atmospheric physics, space plasma physics, solar physics, earth observations, astronomy, astrophysics, life sciences and material sciences are reviewed. Analyses of the Spacelab environment and the Spacelab-to-orbiter and Spacelab-to-experiment interactions are also planned.

  5. "Europe lands on Mars" - Media event at ESA/ESOC

    NASA Astrophysics Data System (ADS)

    2003-11-01

    Launched on 2 June 2003 from Baikonur (Kazakhstan) on board a Russian Soyuz operated by Starsem, the European probe - built for ESA by a European team of industrial companies led by Astrium - carries seven scientific instruments that will perform a series of remote-sensing experiments designed to shed new light on the Martian atmosphere, the planet's structure and its geology. In particular, the British-made Beagle 2 lander will contribute to the search for traces of life on Mars through exobiology experiments and geochemistry research. On board Mars Express tests have been run to check that the instruments are functioning correctly. Mars Express has successfully come through its first power test on the whole spacecraft after the gigantic solar flare on 28 October. Since 17 November the onboard software has been 'frozen' after several updates and the spacecraft is now quietly proceeding to its destination. Before even entering into Martian orbit to perform its mission, Mars Express has to face another challenge: safely delivering the Beagle 2 lander to its destination. This task, starting on 19 December, will not be without risk. First of all, to deliver the lander where planned, Mars Express has been put on a collision course with Mars, since Beagle 2 does not have a propulsion system of its own and must therefore be 'carried' precisely to its destination. This means that after separation, Mars Express has to veer away quickly to avoid crashing onto the planet. During the cruise Beagle 2 will take its power from the mother spacecraft, Mars Express. After separation and until its solar arrays are fully deployed on the surface, Beagle 2 must rely on its own battery, which cannot last beyond 6 days. So, like a caring parent, Mars Express must release Beagle 2 at the last possible moment to ensure that the lander has enough power for the rest of its journey to the surface. Only then can Mars Express change its orientation and rapidly fire the thrusters to get away

  6. Mission to the Moon: An ESA study on future exploration

    NASA Technical Reports Server (NTRS)

    Chicarro, A. F.

    1993-01-01

    The increasing worldwide interest in the continuation of lunar exploration has convinced ESA to carry out an investigation of the motivations to return to the Moon to establish a permanent or a semi-permanent manned lunar base. This study also considers the possible role Europe could play in the future exploration and possible utilization of the Moon. The study concentrated in this first phase mainly on scientific questions, leaving technological issues such as transportation, the role of humans, infrastructure, and policy matters to a later phase. It only partially considered questions relating to the exploitation of lunar resources and the impact of human activities on science.

  7. NASA/ESA CV-990 Spacelab Simulation (ASSESS 2)

    NASA Technical Reports Server (NTRS)

    1977-01-01

    Cost effective techniques for addressing management and operational activities on Spacelab were identified and analyzed during a ten day NASA-ESA cooperative mission with payload and flight responsibilities handled by the organization assigned for early Spacelabs. Topics discussed include: (1) management concepts and interface relationships; (2) experiment selection; (3) hardware development; (4) payload integration and checkout; (5) selection and training of mission specialists and payload specialists; (6) mission control center/payload operations control center interactions with ground and flight problems; (7) real time interaction during flight between principal investigators and the mission specialist/payload specialist flight crew; and (8) retrieval of scientific data and its analysis.

  8. Overview on calibration and validation activities for ESA's Soil Moisture and Ocean Salinity mission

    NASA Astrophysics Data System (ADS)

    Mecklenburg, S.; Bouzinac, C.; Delwart, S.

    2009-04-01

    performances. Other activities include the deployment of the ground-based ESA funded ELBARA radiometers. Also, in collaboration with the Portuguese Meteorological Institute in Lisbon (Portugal), currently hosting the EUMETSAT Land-SAF, ESA funds the establishment of a soil moisture network data hosting facility in support to the SMOS calibration and validation activities. The validation of sea surface salinity data products will be a challenging task requiring a highly accurate and stable instrument calibration. At local scales, the foreseen validation activities are focused on a better understanding of the emission of L-band radiation from the sea surface through dedicated airborne campaigns, whereas validation at global scales will rely on buoy networks and basin scale ocean models. Close collaboration with the NASA Aquarius Team will further contribute to the validation of sea surface salinity data products. A variety of campaigns, such as DOMEX, CoSMOS, WISE, LOSAC, EUROSTARRS, FROG, SMOSREX have been (and will be) performed to investigate uncertainties in the soil moisture and ocean salinity retrieval. The major aspects to investigate with regard to soil moisture are the influence of the various types of vegetation and their seasonal variability, as well as the influence of surface roughness. Over oceans, the impact of sea-surface state on the polarimetric radiometric signal is the main issue. The DOMEX campaigns will provide information for vicarious calibration over Antarctica. The presentation will provide an overview on the calibration and validation activities presently planned in preparation for the SMOS mission.

  9. Overview on calibration and validation activities for ESA's Soil Moisture and Ocean Salinity Mission

    NASA Astrophysics Data System (ADS)

    Mecklenburg, Susanne; Bouzinac, Catherine; Delwart, Steven

    2010-05-01

    exercise to verify that the methodology proposed actually meets the foreseen performances. Other activities include the deployment of the ground-based ESA funded ELBARA radiometers. Also, in collaboration with the Technical University Vienna, ESA funds the establishment of a soil moisture network data hosting facility in support to the SMOS calibration and validation activities. The validation of sea surface salinity data products will be a challenging task requiring a highly accurate and stable instrument calibration. At local scales, the foreseen validation activities are focused on a better understanding of the emission of L-band radiation from the sea surface through dedicated airborne campaigns, whereas validation at global scales will rely on buoy networks and basin scale ocean models. Close collaboration with the NASA Aquarius Team will further contribute to the validation of sea surface salinity data products. A variety of campaigns, such as DOMEX, CoSMOS, WISE, LOSAC, EUROSTARRS, FROG, SMOSREX have been (and will be) performed to investigate uncertainties in the soil moisture and ocean salinity retrieval. The major aspects to investigate with regard to soil moisture are the influence of the various types of vegetation and their seasonal variability, as well as the influence of surface roughness. Over oceans, the impact of sea-surface state on the polarimetric radiometric signal is the main issue. The DOMEX campaigns will provide information for vicarious calibration over Antarctica. The presentation will provide an overview on the calibration and validation activities carried out in the SMOS commissioning phase.

  10. Collisional Line-Shape and Line-Mixing Parameters for CO(2) Absorption near 3340 cm(-1): Measurements and Modeling

    NASA Astrophysics Data System (ADS)

    Buldyreva, Jeanna; Auwera, Jean Vander

    2014-06-01

    class="MsoNormal">The present work is focused on the determination of line-shape parameters for one of the 12C16O2 bands detectable by the SOIR (Solar Occultation in the InfraRed) instrument onboard the ESA Venus Express spacecraft, namely the 21102 - 00001 band located near 3340 cm-1. High-resolution Fourier transform spectra of this band have been recorded at sub-atmospheric pressures and analyzed to extract isolated-line intensities and collisional parameters as well as first-order line-mixing coefficients. Voigt, hard-collision Rautian and Sobel'man, and quadratic-speed-dependent Voigt profiles have been used. The retrieved parameters are compared with previous data available in the literature and with theoretical estimates obtained by an Energy-Corrected Sudden approach (generally, non-Markovian) employing a symmetric metric in the Liouville space. The same approach, supplied with additional hypotheses for basic transition rates for the hot bands, has also been used to model the complete band shapes. The need for accounting of line-narrowing effects at sub-atmospheric pressures has been evidenced from comparison with the recorded spectra, and some improvements have been introduced in the relaxation matrix model, leading to a good agreement of calculated and measured absorptions from nearly Doppler pressure regime to nearly atmospheric pressure.

  11. The Science Operations of the ESA JUICE mission

    NASA Astrophysics Data System (ADS)

    Altobelli, Nicolas; Cardesin, Alejandro; Costa, Marc; Frew, David; Lorente, Rosario; Vallat, Claire; Witasse, Olivier; Christian, Erd

    2016-10-01

    The JUpiter ICy moons Explorer (JUICE) mission was selected by ESA as the first L-Class Mission in the Cosmic Vision Programme. JUICE is an ESA-led mission to investigate Jupiter, the Jovian system with particular focus on habitability of Ganymede and Europa.JUICE will characterise Ganymede and Europa as planetary objects and potential habitats, study Ganymede, Europa, Callisto and Io in the broader context of the system of Jovian moons, and focus on Jupiter science including the planet, its atmosphere and the magnetosphere as a coupled system.The Science Operation Centre (SOC) is in charge of implementing the science operations of the JUICE mission. The SOC aims at supporting the Science Working Team (SWT) and the Science Working Groups (WGs) performing studies of science operation feasibility and coverage analysis during the mission development phase, high level science planning during the cruise phase, and routine consolidation of instrument pointing and commanding timeline during the nominal science phase.We will present the current status of the SOC science planning activities with an overview of the tools and methods in place in this early phase of the mission.

  12. The ESA-ESTEC New Large EMC Facility

    NASA Astrophysics Data System (ADS)

    Suchail, J.; de Groot, H.

    2004-08-01

    This paper presents the new ESA -ESTEC large EMC facility, called Maxwell. The net dimensions between the absorber tips of this EMC chamber (14.5m x 10.7m x 11m) make it compatible with Ariane-5 single passenger launch configuration satellites, in line with the other Environmental Test Facilities already existing at ESA - ESTEC, complementing the mechanical vibration (HYDRA), acoustic (LEAF), thermal vacuum (LSS) and antenna/payload radio-frequency test facilities (CPTR). Access for the specimen to the EMC chamber is made possible through a large dimension door (6m wide x 11m high), using a non-conductive 5m x 5m air cushion pallet sliding on an anti-static epoxy coated floor. A specially designed air cooled high power dissipation wall provides the possibility of testing high power telecommunication satellites with a dissipation capability for RF spots up to densities of 3W/cm2. High cleanliness absorbers lining the ceiling, the floor and the man doors have been installed as well as state of the art fire detection and suppression systems in order to ensure a safe testing of Flight Model satellites.

  13. Status of the ESA L1 mission candidate ATHENA

    NASA Astrophysics Data System (ADS)

    Rando, N.; Martin, D.; Lumb, D.; Verhoeve, P.; Oosterbroek, T.; Bavdaz, M.; Fransen, S.; Linder, M.; Peyrou-Lauga, R.; Voirin, T.; Braghin, M.; Mangunsong, S.; van Pelt, M.; Wille, E.

    2012-09-01

    ATHENA (Advanced Telescope for High Energy Astrophysics) was an L class mission candidate within the science programme Cosmic Vision 2015-2025 of the European Space Agency, with a planned launch by 2022. ATHENA was conceived as an ESA-led project, open to the possibility of focused contributions from JAXA and NASA. By allowing astrophysical observations between 100 eV and 10 keV, it would represent the new generation X-ray observatory, following the XMM-Newton, Astro-H and Chandra heritage. The main scientific objectives of ATHENA include the study of large scale structures, the evolution of black holes, strong gravity effects, neutron star structure as well as investigations into dark matter. The ATHENA mission concept would be based on focal length of 12m achieved via a rigid metering tube and a twoaperture, x-ray telescope. Two identical x-ray mirrors would illuminate fixed focal plane instruments: a cryogenic imaging spectrometer (XMS) and a wide field imager (WFI). The S/C is designed to be fully compatible with Ariane 5 ECA. The observatory would operate at SE-L2, with a nominal lifetime of 5 yr. This paper provides a summary of the reformulation activities, completed in December 2011. An overview of the spacecraft design and of the payload is provided, including both telescope and instruments. Following the ESA Science Programme Committee decision on the L1 mission in May 2012, ATHENA was not selected to enter Definition Phase.

  14. The ESA TTP and Recent Spin-off Successes

    NASA Astrophysics Data System (ADS)

    Raitt, D.; Brisson, P.

    2002-01-01

    In the framework of its research and development activities, the European Space Agency (ESA) spends some 250m each year and, recognizing the enormous potential of the know-how developed within its R&D activities, set up a Technology Transfer Programme (TTP) some twelve years ago. Over the years, the Programme has achieved some remarkable results with 120 successful transfers of space technologies to the non-space sector; over 120m received by companies making the technologies available; some 15 new companies established as a direct result of exploiting technologies; nearly 2500 jobs created or saved in Europe; and a portfolio of some 300 (out of over 600) active space technologies available for transfer and licencing. Some of the more recent technologies which have been successfully transferred to the non-space sector include the Mamagoose baby safety pyjamas; a spectrographic system being used to compare colours in fabrics and textiles; Earth observation technology employed to assess remotely how much agrochemicals are being used by farmers; and the Dutch solar car, Nuna, which, using European space technologies, finished first in the 2001 World Solar Challenge breaking all records. The paper will give a brief overview of the ESA Technology Transfer Programme and describe some of its recent successful technology transfers.

  15. Evaluating ESA CCI soil moisture in East Africa

    NASA Astrophysics Data System (ADS)

    McNally, Amy; Shukla, Shraddhanand; Arsenault, Kristi R.; Wang, Shugong; Peters-Lidard, Christa D.; Verdin, James P.

    2016-06-01

    To assess growing season conditions where ground based observations are limited or unavailable, food security and agricultural drought monitoring analysts rely on publicly available remotely sensed rainfall and vegetation greenness. There are also remotely sensed soil moisture observations from missions like the European Space Agency (ESA), Soil Moisture and Ocean Salinity (SMOS) and NASA's Soil Moisture Active Passive (SMAP); however, these time series are still too short to conduct studies that demonstrate the utility of these data for operational applications, or to provide historical context for extreme wet or dry events. To promote the use of remotely sensed soil moisture in agricultural drought and food security monitoring, we evaluate the quality of a 30+ year time series of merged active-passive microwave soil moisture from the ESA Climate Change Initiative (CCI-SM) over East Africa. Compared to the Normalized Difference Vegetation index (NDVI) and modeled soil moisture products, we find substantial spatial and temporal gaps in the early part of the CCI-SM record, with adequate data coverage beginning in 1992. From this point forward, growing season CCI-SM anomalies are well correlated (R > 0.5) with modeled soil moisture, and in some regions, NDVI. We use pixel-wise correlation analysis and qualitative comparisons of seasonal maps and time series to show that remotely sensed soil moisture can inform remote drought monitoring that has traditionally relied on rainfall and NDVI in moderately vegetated regions.

  16. The ESA SMART-1 Mission to the Moon: Goals and Science

    NASA Astrophysics Data System (ADS)

    Foing, B. H.; Racca, G. R.; SMART-1 Science and Technology Working Team

    2000-10-01

    SMART-1 is the first in the programme of ESA's Small Missions for Advanced Research and Technology . Its objective is to demonstrate Solar Electric Primary Propulsion (SEP) for future Cornerstones (such as Bepi-Colombo) and to test new technologies for spacecraft and instruments. The project aims to have the spacecraft ready in October 2002 for launch as an Ariane-5 auxiliary payload. After a cruise with primary SEP, the SMART-1 mission is to orbit the Moon for a nominal period of six months, with possible extension. The spacecraft will carry out a complete programme of scientific observations during the cruise and in lunar orbit. SMART-1's science payload, with a total mass of some 15 kg, features many innovative instruments and advanced technologies. A miniaturised high-resolution camera (AMIE) for lunar surface imaging, a near-infrared point-spectrometer (SIR) for lunar mineralogy investigation, and a very compact X-ray spectrometer (D-CIXS) with a new type of detector and micro-collimator which will provide fluorescence spectroscopy and imagery of the Moon's surface elemental composition. The payload also includes an experiment (KaTE) aimed at demonstrating deep-space telemetry and telecommand communications in the X and Ka-bands, a radio-science experiment (RSIS), a deep space optical link (Laser-Link Experiment), using the ESA Optical Ground station in Tenerife, and the validation of a system of autonomous navigation SMART-1 lunar science investigations include studies of the chemical (OBAN) based on image processing. SMART-1 lunar science investigations include studies of the chemica composition and evolution of the Moon, of geophysical processes (volcanism, tectonics, cratering, erosion, deposition of ices and volatiles) for comparative planetology, and high resolution studies in preparation for future steps of lunar exploration. The mission could address several topics such as the accretional processes that led to the formation of planets, and the origin

  17. NASA's Deep Space Network and ESA's Tracking Network Collaboration to Enable Solar System Exploration

    NASA Astrophysics Data System (ADS)

    Asmar, Sami; Accomazzo, Andrea; Firre, Daniel; Ferri, Paolo; Liebrecht, Phil; Mann, Greg; Morse, Gary; Costrell, Jim; Kurtik, Susan; Hell, Wolfgang; Warhaut, Manfred

    2016-07-01

    Planetary missions travel vast distances in the solar system to explore and answer important scientific questions. To return the data containing their discoveries, communications challenges have to be overcome, namely the relatively low transmitter power, typically 20 Watts at X-band, and the one-over-the-square of the distance loss of the received power, among other factors. These missions were enabled only when leading space agencies developed very large communications antennas to communicate with them as well as provide radio-metric navigation tools. NASA's Deep Space Network (DSN) and ESA's ESTRACK network are distributed geographically in order to provide global coverage and utilize stations ranging in size from 34 m to 70 m in diameter. With the increasing number of missions and significant loading on networks' capacity, unique requirements during critical events, and long-baseline interferometry navigation techniques, it became obvious that collaboration between the networks was necessary and in the interest of both agencies and the advancement of planetary and space sciences. NASA and ESA established methods for collaboration that include a generic cross-support agreement as well as mission-specific memoranda of understanding. This collaboration also led to the development of international inter-operability standards. As a result of its success, the DSN-ESTRACK cross support approach is serving as a model for other agencies with similar stations and an interest in collaboration. Over recent years, many critical events were supported and some scientific breakthroughs in planetary science were enabled. This paper will review selected examples of the science resulting from this work and the overall benefits for deep space exploration, including lessons learned, from inter-agency collaboration with communications networks.

  18. Harmonisation and diagnostics of MIPAS ESA CH4 and N2O profiles using data assimilation

    NASA Astrophysics Data System (ADS)

    Errera, Quentin; Ceccherini, Simone; Christophe, Yves; Chabrillat, Simon; Hegglin, Michaela I.; Lambert, Alyn; Ménard, Richard; Raspollini, Piera; Skachko, Sergey; van Weele, Michiel; Walker, Kaley A.

    2016-12-01

    This paper discusses assimilation experiments of methane (CH4) and nitrous oxide (N2O) profiles retrieved from the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS). Here we focus on data versions 6 and 7 provided by the ESA processor. These data sets have been assimilated by the Belgian Assimilation System for Chemical ObsErvations (BASCOE). The CH4 and N2O retrieved profiles can oscillate, especially in the tropical lower stratosphere. Using the averaging kernels of the observations and a background error covariance matrix, which has previously been calibrated, allows the system to partly remedy this issue and provide assimilated fields that are more regular vertically. In general, there is a good agreement between the BASCOE analyses and independent observations from ACE-FTS (CH4 and N2O) and MLS (N2O), demonstrating the general good quality of CH4 and N2O retrievals provided by MIPAS ESA. Nevertheless, this study also identifies two issues in these data sets. First, time series of the observations show unexpected discontinuities due to an abrupt change in the gain of MIPAS band B, generally occurring after the instrument decontamination. Since the calibration is performed weekly, the abrupt change in the gain affects the measurements until the subsequent calibration is performed. Second, the correlations between BASCOE analyses and independent observations are poor in the lower stratosphere, especially in the tropics, probably due to the presence of outliers in the assimilated data. In this region, we recommend using MIPAS CH4 and N2O retrievals with caution.

  19. CERN, ESA and ESO Launch "Physics On Stage"

    NASA Astrophysics Data System (ADS)

    2000-03-01

    Physics is everywhere . The laws of physics govern the Universe, the Sun, the Earth and even our own lives. In today's rapidly developing society, we are becoming increasingly dependent on high technology - computers, transport, and communication are just some of the key areas that are the result of discoveries by scientists working in physics. But how much do the citizens of Europe really know about physics? Here is a unique opportunity to learn more about this elusive subject! [Go to Physics On Stage Website] Beginning in February 2000, three major European research organisations are organising a unique Europe-wide programme to raise the public awareness of physics and related sciences. "Physics on Stage" is launched by the European Laboratory for Particle Physics (CERN) , the European Space Agency (ESA) and the European Southern Observatory (ESO) , with support from the European Union. Other partners are the European Physical Society (EPS) and the European Association for Astronomy Education (EAAE). This exciting programme is part of the European Week for Science and Technology and will culminate in a Science Festival during November 6-11, 2000, on the CERN premises at the French-Swiss border near Geneva. Why "Physics on Stage"? The primary goal of "Physics on Stage" is to counteract the current decline in interest and knowledge about physics among Europe's citizens by means of a series of highly visible promotional activities. It will bring together leading scientists and educators, government bodies and the media, to confront the diminishing attraction of physics to young people and to develop strategies to reverse this trend. The objective in the short term is to infuse excitement and to provide new educational materials. In the longer term, "Physics on Stage" will generate new developments by enabling experts throughout Europe to meet, exchange and innovate. "Physics on Stage" in 22 European Countries "Physics on Stage" has been initiated in 22 European

  20. ESA `Huygens and Mars Express' science highlights - call to press

    NASA Astrophysics Data System (ADS)

    2005-11-01

    Almost one year has passed since ESA’s Huygens probe landed on Saturn’s largest moon, Titan. Today, a set of new wide-ranging results from the probe’s two-and-a-half hour descent and landing, part of the extraordinary NASA/ESA/ASI Cassini-Huygens mission to Saturn and its moons, is ready for release. At the same time, ESA’s Mars Express mission is continuing its investigations of Mars, painting a new picture of the 'red planet'. This includes the first ever probing below the surface of Mars, new geological clues with implications for the climate, newly-discovered surface and atmospheric features and, above all, traces of the presence of water on this world. These and other exciting findings from just one year of observations and data analysis - in the context of ESA’s overall scientific achievements - will be the focus of a press conference to be held at ESA Headquarters in Paris at 16:00 on 30 November 2005. Media interested in attending are invited to complete the following registration form. Press conference programme Space Science Highlights 2005 From Huygens to Mars Express 30 November 2005, 16:00 hrs Room 137, European Space Agency Headquarters 8-10 Rue Mario-Nikis, F-75738 Paris Cedex, France 15:30 - Registration 16:00 - A Year of European Space Science Successes Prof. David Southwood, ESA Director of Science Programme 16:10 - Highlights of the Huygens Mission Results Jean-Pierre Lebreton, ESA Huygens Project Scientist 16:15 - Robin Duttaroy, Co-Investigator, Doppler Wind Experiment, University of Bonn, Germany 16:20 - Marcello Fulchignoni , Principal Investigator, Huygens Atmospheric Structure Instrument, Université de Paris 7, France 16:25 - John Zarnecki, Principal Investigator, Surface Science Package, Open University, UK 16:30 - François Raulin, Co-Investigator, Gas Chromatograph Mass Spectrometer, Université de Paris 12 - Créteil, France 16:35 - Guy Israel, Principal Investigator, Aerosol Collector and Pyrolyser, Service d

  1. Understanding the features in the ultrafast transient absorption spectra of CdSe quantum dots

    NASA Astrophysics Data System (ADS)

    Zhang, Cheng; Do, Thanh Nhut; Ong, Xuanwei; Chan, Yinthai; Tan, Howe-Siang

    2016-12-01

    We describe a model to explain the features of the ultrafast transient absorption (TA) spectra of CdSe core type quantum dots (QDs). The measured TA spectrum consists of contributions by the ground state bleach (GSB), stimulated emission (SE) and excited state absorption (ESA) processes associated with the three lowest energy transition of the QDs. We model the shapes of the GSB, SE and ESA spectral components after fits to the linear absorption. The spectral positions of the ESA components take into account the biexcitonic binding energy. In order to obtain the correct weightage of the GSB, SE and ESA components to the TA spectrum, we enumerate the set of coherence transfer pathways associated with these processes. From our fits of the experimental TA spectra of 65 Å diameter QDs, biexcitonic binding energies for the three lowest energy transitions are obtained.

  2. Bold ideas shortlisted for future ESA science projects

    NASA Astrophysics Data System (ADS)

    2000-03-01

    ESA's science programme introduced flexi-missions in 1997, to achieve greater flexibility. They replace the medium-scale projects, of which Huygens (Titan lander) and Integral (gamma-ray astronomy) are current examples. The aim is to have two flexi-missions for the price of one medium mission. Mars Express, already under construction for launch in 2003, is the first flexi-mission, or F1. Now under consideration are F2 and F3, each with a cost to ESA of no more than 176 million euros at 1999 prices. The frontrunner in the astronomy field for one of these slots is European participation with NASA in the Next Generation Space Telescope, successor to the NASA-ESA Hubble Space Telescope. Although a formal decision will not be taken until later this year, much European effort has already gone into preparing for this NGST project, due for launch in 2008. That intensifies the competition for the other slot. An embarrassment of riches - of ideas Multinational teams of scientists from Europe's universities and research institutes are backing each of the proposals selected for assessment, half of which concern the Solar System and the Earth's space environment. STORMS is a scheme to use three spacecraft to investigate a source of big trouble for technological systems, after solar eruptions. The "ring current" of energetic charged particles circulates around the equator at altitudes of several times the Earth's radius, and when its intensity varies during solar storms it causes magnetic perturbations at the Earth's surface. Three identical spacecraft, orbiting out to 50,000 kilometres and equally spaced around the equator, could clear up several remaining mysteries of the ring current -- and also provide real-time monitoring of magnetic storms. SOLAR ORBITER would fly on an extended orbit taking it at intervals to within about 30 million kilometres of the Sun -- much closer than the innermost planet, Mercury. At its closest approach the spacecraft would round the Sun at

  3. Optical and dark characterization of the PLATO CCD at ESA

    NASA Astrophysics Data System (ADS)

    Verhoeve, Peter; Prod'homme, Thibaut; Oosterbroek, Tim; Duvet, Ludovic; Beaufort, Thierry; Blommaert, Sander; Butler, Bart; Heijnen, Jerko; Lemmel, Frederic; van der Luijt, Cornelis; Smit, Hans; Visser, Ivo

    2016-07-01

    PLATO - PLAnetary Transits and Oscillations of stars - is the third medium-class mission (M3) to be selected in the European Space Agency (ESA) Science and Robotic Exploration Cosmic Vision programme. It is due for launch in 2025 with the main objective to find and study terrestrial planets in the habitable zone around solar-like stars. The payload consists of >20 cameras; with each camera comprising 4 Charge-Coupled Devices (CCDs), a large number of flight model devices procured by ESA shall ultimately be integrated on the spacecraft. The CCD270 - specially designed and manufactured by e2v for the PLATO mission - is a large format (8 cm x 8 cm) back-illuminated device operating at 4 MHz pixel rate and coming in two variants: full frame and frame transfer. In order to de-risk the PLATO CCD procurement and aid the mission definition process, ESA's Payload Technology Validation section is currently validating the PLATO CCD270. This validation consists in demonstrating that the device achieves its specified electrooptical performance in the relevant environment: operated at 4 MHz, at cold and before and after proton irradiation. As part of this validation, CCD270 devices have been characterized in the dark as well as optically with respect to performance parameters directly relevant for the photometric application of the CCDs. Dark tests comprise the measurement of gain sensitivity to bias voltages, charge injection tests, and measurement of hot and variable pixels after irradiation. In addition, the results of measurements of Quantum Efficiency for a range of angles of incidence, intra- pixel response (non-)uniformity, and response to spot illumination, before and after proton irradiation. In particular, the effect of radiation induced degradation of the charge transfer efficiency on the measured charge in a star-like spot has been studied as a function of signal level and of position on the pixel grid, Also, the effect of various levels of background light on the

  4. Analysis and Optimization of the Recovered ESA Huygens Mission

    NASA Astrophysics Data System (ADS)

    Kazeminejad, Bobby

    2002-06-01

    The Huygens Probe is the ESA-provided element of the joint NASA/ESA Cassini - Huygens mission to Saturn and Titan. A recently discovered design flaw in the Huygens radio receiver onboard Cassini led to a significantly different mission geometry, redesigned and implemented by both the ESA Huygens and NASA Cassini project teams. A numerical integration of the Orbiter trajectory and the Huygens descent profile with simplified assumptions for Probe attitude and correlated aerodynamic aspects offered the opportunity to re-calculate key mission parameters, which depend on the relative geometry and motion of the bodies. This was a crucial step to assess whether science-imposed constraints were not violated. A review of existing Titan wind and atmosphere models and their physical background led to a subsequent parametric study of their impact on the supersonic entry phase, the parachute descent and finally the bodyfixed landing coordinates of the Probe. In addition to the deterministic (nominal) Probe trajectory, it is important to quantify the influence of various uncertainties that enter into the equations of motion on the results (e.g., state vectors, physical parameters of the environment and the Probe itself). This was done by propagating the system covariance matrix together with the nominal state vectors. A sophisticated Monte Carlo technique developed to save up computation time was then used to determine statistical percentiles of the key parameters. The Probe Orbiter link geometry was characterized by evaluating the link budget and received frequency at receiver level. In this calculation the spin of the Probe and the asymmetric gain pattern of the transmitting antennas was taken into account. The results were then used in a mathematical model that describes the tracking capability of the receiver symbol synchronizer. This allowed the loss of data during the mission to be quantified. A subsequent parametric study of different sets of mission parameters with the

  5. The X/Ka Celestial Reference Frame: Results from combined NASA-ESA baselines including Malargüe, Argentina

    NASA Astrophysics Data System (ADS)

    Jacobs, Christopher S.; Clark, J. E.; Garcí-Miró, C.; Goodhart, C. E.; Horiuchi, S.; Madde, R.; Mercolino, M.; Naudet, C. J.; Snedeker, L. G.; Sotuela, I.; White, L. A.

    2014-03-01

    An X/Ka-band (8.4/32 GHz) celestial reference frame has been constructed using a combined NASA and ESA Deep Space Network. Observations at X/Ka-band are motivated by their ability to access more compact source morphology and reduced core shift relative to observations at the historically standard S/X-band. In 86 observing sessions we detected 631 sources covering the full 24 hours of right ascension and the full range of declinations. The collaboration between NASA and ESA's deep space antenna in Malargüe, Argentina was created with an emphasis on addressing weaknesses in the southern hemisphere. The accuracy of the resulting CRF was quantified by comparison of 520 X/Ka sources in common with the S/X-band (2.3/8.4 GHz) ICRF2 producing wRMS agreement of 175 μas in RA cos(dec) and 220 μas in Declination. There is evidence for systematic errors at the ~100 μas level. Known errors include limited SNR, lack of phase calibration, troposphere mismodelling, and terrestrial frame distortions. Actions are underway to reduce all of these errors. The recent successful launch of the Gaia optical astrometric satellite motivates work to tie the radio and optical frames. Existing X/Ka data and simulated Gaia data predict a frame tie precision of ~10 μas (1-sigma, per 3-D rotation component) with anticipated improvements having the potential to produce a tie of 5 μas per component. If XKa precision can be pushed below 100 µas, the XKa frame has potential to produce a tie to Gaia that is superior to S/X due to reduced astrophysical systematics at X/Ka relative to S/X.

  6. The ESA Meteoroid Model 2010: Enhanced Physical Model

    NASA Astrophysics Data System (ADS)

    Dikarev, Valeri; Mints, Alexey; Drolshagen, Gerhard

    The orbital distributions of meteoroids in interplanetary space are revised in the ESA meteoroid model. In the present update, the chemical composition of the meteoroids is simulated in more detail than in the previous meteoroid models. Silicate and carbonaceous fractions are introduced for all meteoroid populations, and in addition to asteroids and Jupiter-crossing comets, comet 2P/Encke is added as a source. The orbital evolution under planetary gravity, Poynting-Robertson effect and mutual collisions is simulated using analytical approximations. Infrared observations of the zodiacal cloud by the COBE DIRBE instrument, in situ flux measurements by the dust detectors on board Galileo, Ulysses, Pioneer 11 and Helios-1 spacecraft, and the crater size distributions on lunar rock samples retrieved by the Apollo missions are incorporated in the model.

  7. THOR - a mission candidate for ESA M4

    NASA Astrophysics Data System (ADS)

    Vaivads, Andris

    2015-04-01

    We present a mission concept THOR (http://thor.irfu.se) that was proposed in the response to the ESA M4 Call. The scientific theme of the THOR mission is turbulent energy dissipation and particle energization. The main focus is on turbulence and shock processes, however areas where the different fundamental processes interact, such as reconnection in turbulence or shock generated turbulence, is also of high importance. The THOR mission aims to address such fundamental questions as how energy is dissipated at kinetic scales, how energy is partitioned among different plasma components, what is the relative importance of waves and coherent structures in the dissipation processes. To reach the goal a careful design work of the THOR mission and its payload has been done and it is based on the earlier mission concepts of Tor, EIDOSCOPE and Cross-Scale. We present the basic concepts of the THOR mission, THOR's payload and the major science questions to be addressed.

  8. Science Operations For Esa's Smart-1 Mission To The Moon

    NASA Astrophysics Data System (ADS)

    Almeida, M.; Foing, B.; Heather, D.; Marini, A.; Lumb, R.; Racca, G.

    The primary objective of the European Space Agency's SMART-1 mission to the Moon is to test and validate a new electric propulsion engine for potential use on other larger ESA Cornerstone missions. However, the SMART-1 spacecraft will also carry a number of scientific instruments and experiments for use en-route to and in orbit about the Moon. SMART-1's major operational constraint is that it will be only contacted twice per week. As a result, there will be a stronger emphasis on mid-term planning, and the spacecraft will be operated using a large list of telecommands sent during the communication windows. This approach leads to a higher probability of there being resource and/or instruments conflicts. To eliminate these, two software tools were developed: the Experiment Planning System (EPS), and the Project Test Bed (PTB). These tools will also allow us to predict the lunar coverage of the scien- tific instruments, and to simulate target selections.

  9. Reference payload of the ESA L1 mission candidate ATHENA

    NASA Astrophysics Data System (ADS)

    Martin, Didier; Rando, Nicola; Lumb, David; Verhoeve, Peter; Oosterbroek, Tim; Bavdaz, Marcos

    2012-09-01

    The Advanced Telescope for High ENergy Astrophysics (ATHENA) is one of the three candidates that competed for the first large-class mission (L1) in ESA’s Cosmic Vision 2015-2025 programme, with a launch planned by 2022 and is the result of the IXO reformulation activities. ATHENA is an ESA-led project and is conceived as the next generation X-ray observatory. It is meant to address fundamental questions about accretion around black-holes, reveal the physics underpinning cosmic feedback, trace the large scale structure of baryons in galaxy clusters and the cosmic as well as a large number of astrophysics and fundamental physics phenomena. The observatory consists of two identical mirrors each illuminating a fixed focal plane instrument, providing collectively 1 m2 effective area at 1 keV. The reference payload consists of a medium resolution wide field imager (WFI) and a high resolution X-ray micro-calorimeter spectrometer (XMS). The WFI is based on a monolithic Si DepFET array providing imaging over a 24 × 24 arcmin2 field of view and a good PSF oversampling. The sensor will measure X-rays in the range 0.1-15 keV and provides near Fano limited energy resolution (150eV at 6keV). The XMS is based on a micro-calorimeter array operating at its transition temperature of ~100mK and provides <3eV resolution. The detector array consists of 32 × 32 pixels covering a 2.3 × 2.3 arcmin2 field of view, co-aligned with the WFI. This paper summarizes the results of the reformulation exercise and provides details on the payload complement and its accommodation on the spacecraft. Following the ESA Science Programme Committee decision on the L1 mission in May 2012, ATHENA was not selected to enter Definition Phase.

  10. SOHO Mission Interruption Joint NASA/ESA Investigation Board

    NASA Technical Reports Server (NTRS)

    1998-01-01

    Contact with the SOlar Heliospheric Observatory (SOHO) spacecraft was lost in the early morning hours of June 25, 1998, Eastern Daylight Time (EDT), during a planned period of calibrations, maneuvers, and spacecraft reconfigurations. Prior to this the SOHO operations team had concluded two years of extremely successful science operations. A joint European Space Agency (ESA)/National Aeronautics and Space Administration (NASA) engineering team has been planning and executing recovery efforts since loss of contact with some success to date. ESA and NASA management established the SOHO Mission Interruption Joint Investigation Board to determine the actual or probable cause(s) of the SOHO spacecraft mishap. The Board has concluded that there were no anomalies on-board the SOHO spacecraft but that a number of ground errors led to the major loss of attitude experienced by the spacecraft. The Board finds that the loss of the SOHO spacecraft was a direct result of operational errors, a failure to adequately monitor spacecraft status, and an erroneous decision which disabled part of the on-board autonomous failure detection. Further, following the occurrence of the emergency situation, the Board finds that insufficient time was taken by the operations team to fully assess the spacecraft status prior to initiating recovery operations. The Board discovered that a number of factors contributed to the circumstances that allowed the direct causes to occur. The Board strongly recommends that the two Agencies proceed immediately with a comprehensive review of SOHO operations addressing issues in the ground procedures, procedure implementation, management structure and process, and ground systems. This review process should be completed and process improvements initiated prior to the resumption of SOHO normal operations.

  11. ESA's Planetary Science Archive: International collaborations towards transparent data access

    NASA Astrophysics Data System (ADS)

    Heather, David

    The European Space Agency's (ESA) Planetary Science Archive (PSA) is the central repository for science data returned by all ESA planetary missions. Current holdings include data from Giotto, SMART-1, Cassini-Huygens, Mars Express, Venus Express, and Rosetta. In addition to the basic management and distribution of these data to the community through our own interfaces, ESA has been working very closely with international partners to globalize the archiving standards used and the access to our data. Part of this ongoing effort is channelled through our participation in the International Planetary Data Alliance (IPDA), whose focus is on allowing transparent and interoperable access to data holdings from participating Agencies around the globe. One major focus of this work has been the development of the Planetary Data Access Protocol (PDAP) that will allow for the interoperability of archives and sharing of data. This is already used for transparent access to data from Venus Express, and ESA are currently working with ISRO and NASA to provide interoperable access to ISRO's Chandrayaan-1 data through our systems using this protocol. Close interactions are ongoing with NASA's Planetary Data System as the standards used for planetary data archiving evolve, and two of our upcoming missions are to be the first to implement the new 'PDS4' standards in ESA: BepiColombo and ExoMars. Projects have been established within the IPDA framework to guide these implementations to try and ensure interoperability and maximise the usability of the data by the community. BepiColombo and ExoMars are both international missions, in collaboration with JAXA and IKI respectively, and a strong focus has been placed on close interaction and collaboration throughout the development of each archive. For both of these missions there is a requirement to share data between the Agencies prior to public access, as well as providing complete open access globally once the proprietary periods have

  12. ESA joins forces with Japan on new infrared sky surveyor

    NASA Astrophysics Data System (ADS)

    2006-02-01

    analysis. This second phase will end with the depletion of the liquid helium needed to cool down the spacecraft telescope and its instruments to only a few degrees above absolute zero. ASTRO-F will then start its third operations phase and continue to make observations of selected celestial targets with its infrared camera only, in a few specific infrared wavelengths. ESA’s involvement: Only two decades have passed since the birth of space-based infrared astronomy; since then, each decade has been marked by the launch of innovative infrared satellites that have revolutionised our very perception of the cosmos. In fact, infrared satellites make possible the detection of cool objects, including planetary systems, interstellar dust and gas, or distant galaxies, all of which are most difficult to study in the visible part of the light spectrum. With infrared astronomy, it is also possible to study the birth of stars and galaxies, the ‘creation’ energy of which peaks in the infrared range. The European Space Agency and Europe have a strong tradition in infrared astronomy, which is now being continued by the participation of the UK, the Netherlands and ESA in ASTRO-F. ESA is providing network support through its ground station in Kiruna (Sweden) for a few passes per day. ESA is also providing expertise and support for the sky-survey data processing. This includes ‘pointing reconstruction’ - which means measuring exactly where the observed objects are in the sky, to help accelerate the production of sky catalogues and ultimately produce a census of the infrared universe. In return, ESA has obtained ten percent of the observing opportunities during the second and third operational phases of the ASTRO-F mission, which is being allocated to European astronomers to perform their proposed observations. “The cooperation offered to ESA by Japan in ASTRO-F will help keep up momentum for European astronomers as they build on their past work with ISO, and look forward to the

  13. ESA and iron therapy in chronic kidney disease: a balance between patient safety and hemoglobin target.

    PubMed

    Hung, Szu-Chun; Tarng, Der-Cherng

    2014-10-01

    Optimal treatment algorithms for erythropoiesis-stimulating agent (ESA) and iron therapy in anemic CKD patients are lacking. Kuragano et al. evaluated hemodialysis patients over two years and report increased mortality risk and/or adverse events in those with high serum ferritin levels and high ferritin fluctuations, and an increase in adverse events in iron users. Clinical practice should avoid disproportionately high ESA or iron doses to achieve hemoglobin targets, particularly in those with significant comorbidity or ESA resistance.

  14. Hubble gets new ESA-supplied solar arrays

    NASA Astrophysics Data System (ADS)

    1993-12-01

    Derek Eaton, ESA project manager, was overjoyed with the success of the day's spacewalk. "To build two such massive arrays some years apart to such tight tolerances and have one replace the other with so few problems is a tribute to the design and manufacturing skills of ESA and British Aerospace, the prime contractor for the arrays", he said. "The skill of Kathy and Tom contributed greatly to this success". The astronauts began their spacewalk at 09h30 p.m. CST (04h30 a.m. CET, Monday). Their first task was to jettison the troublesome solar array that failed to retract yesterday. Perched on the end of the shuttle's robot arm, 7.5 metres above the cargo bay, Thornton carefully released the array. ESA astronaut Claude Nicollier then pulled the arm away from the free-floating panel and mission commander Dick Covey fired the shuttle's thrusters to back away. Endeavour and the discarded array are moving apart at a rate of 18.5 kilometres each 90-minute orbit of the Earth. The array is expected to burn up in the Earth's atmosphere harmlessly within a year or so. The astronauts had no problems installing the new arrays and stowing the left-hand wing in the cargo bay for the return to Earth. The new arrays will remain rolled-up against the side of the telescope until the fifth spacewalk on Wednesday/Thursday. The telescope itself will be deployed on Saturday. The telescope's first set of arrays flexed in orbit because of the sudden swing in temperature as the craft moved in and out of sunlight. The movement, or "jitter", affected the telescope's pointing system and disrupted observations at times. The Space Telescope Operations Control Centre largely compensated for the problem with special software but this occupied a large amount of computer memory. The new arrays incorporate three major changes to eliminate the problem. The metal bi-stem booms, which support the solar blankets, is protected from extreme temperature changes by a concertina-style sleeve made up of one

  15. Earth Observation Training and Education with ESA LearnEO!

    NASA Astrophysics Data System (ADS)

    Byfield, Valborg; Mathieu, Pierre-Philippe; Dobson, Malcolm; Rosmorduc, Vinca; Del Frate, Fabio; Banks, Chris; Picchiani, Matteo

    2013-04-01

    For society to benefit fully from its investment in Earth observation, EO data must be accessible and familiar to a global community of users who have the skills, knowledge and understanding to use the observations appropriately in their work. Achieving this requires considerable education effort. LearnEO! (www.learn-eo.org) is a new ESA education project that contributes towards making this a reality. LearnEO! has two main aims: to develop new training resources that use data from sensors on ESA satellites to explore a variety of environmental topics, and to stimulate and support members of the EO and education communities who may be willing to develop and share new education resources in the future. The project builds on the UNESCO Bilko project, which currently supplies free software, tutorials, and example data to users in 175 countries. Most of these users are in academic education or research, but the training resources are also of interest to a growing number of professionals in government, NGOs and private enterprise. Typical users are not remote sensing experts, but see satellite data as one of many observational tools. They want an easy, low-cost means to process, display and analyse data from different satellite sensors as part of their work in environmental research, monitoring and policy development. Many of the software improvements and training materials developed in LearnEO! are in response to requests from this user community. The LearnEO! tutorial and peer-reviewed lessons are designed to teach satellite data processing and analysis skills at different levels, from beginner to advanced - where advanced lessons requires some previous experience with Earth observation techniques. The materials are aimed at students and professionals in various branches of Earth sciences who have not yet specialised in specific EO technologies. The lessons are suitable for self-study, university courses at undergraduate to MSc level, or for continued professional

  16. In-situ Observations of Space Debris at ESA

    NASA Astrophysics Data System (ADS)

    Drolshagen, G.

    Information on the small size (millimetre or smaller) space debris and meteoroid population in space can only be obtained by in-situ detectors or the analysis of retrieved hardware. Past, ongoing and planned ESA activities in this field are presented. In 1996 the GORID impact detector was launched into a geostationary orbit on-board the Russian Express-2 telecommunication satellite. This impact ionisation detector had a sensor surface of 0.1 m2. Until July 2002 when the spacecraft was shut down it recorded more than 3000 impacts in the micrometre size range. Inter alia, GORID measured numerous clusters of events, believed to result from debris clouds, and indicated that debris fluxes in GEO are larger than predicted by present models. Another in-situ detector, DEBIE-1, was launched in October 2001 and is operating on-board the small technology satellite PROBA in a low polar orbit. It has two sensors, each of 0.01m2 size, pointing in different directions. A second detector of this type, DEBIE-2 with 3 sensors, is ready for flight on the EuTEF carrier (external payload to ISS). The data from GORID and DEBIE-1 are stored on-line in EDID (European Detector Impact Database). Post-flight impact analyses of retrieved hardware provide detailed information on the encountered meteoroid and debris fluxes over a large range of sizes. ESA initiated several analyses in the past ((EURECA, Hubble Space Telescope (HST) solar arrays). The most recent impact analysis was performed for the HST solar arrays retrieved in March 2002. Measured crater sizes in solar cells ranged from about 1 micron to 7 mm. A total of 175 complete penetrations of the 0.7 mm thick arrays were observed. A chemical analysis of impact residues allowed the distinction between space debris and natural meteoroids. Space debris was found to dominate for sizes smaller than 10 microns and larger than about 1 mm. For intermediate sizes impacts are mainly from meteoroids. Results of the analysis and comparisons with

  17. ESA's Integral detects closest cosmic gamma-ray burst

    NASA Astrophysics Data System (ADS)

    2004-08-01

    5 August 2004 A gamma-ray burst detected by ESA's Integral gamma-ray observatory on 3 December 2003 has been thoroughly studied for months by an armada of space and ground-based observatories. Astronomers have now concluded that this event, called GRB 031203, is the closest cosmic gamma-ray burst on record, but also the faintest. This also suggests that an entire population of sub-energetic gamma-ray bursts has so far gone unnoticed... Gamma ray burst model hi-res Size hi-res: 22 KB Credits: CXC/M. Weiss Artist impression of a low-energy gamma-ray burst This illustration describes a model for a gamma-ray burst, like the one detected by Integral on 3 December 2003 (GRB 031203). A jet of high-energy particles from a rapidly rotating black hole interacts with surrounding matter. Observations with Integral on 3 December 2003 and data on its afterglow, collected afterwards with XMM-Newton, Chandra and the Very Large Array telescope, show that GRB 031203 radiated only a fraction of the energy of normal gamma-ray bursts. Like supernovae, gamma-ray bursts are thought to be produced by the collapse of the core of a massive star. However, while the process leading to supernovae is relatively well understood, astronomers still do not know what happens when a core collapses to form a black hole. The discovery of 'under-energetic' gamma-ray bursts, like GRB 031203, should provide valuable clues as to links between supernovae, black holes and gamma-ray bursts. Lo-res JPG (22 Kb) Hi-res TIFF (5800 Kb) Cosmic gamma-ray bursts (GRBs) are flashes of gamma rays that can last from less than a second to a few minutes and occur at random positions in the sky. A large fraction of them is thought to result when a black hole is created from a dying star in a distant galaxy. Astronomers believe that a hot disc surrounding the black hole, made of gas and matter falling onto it, somehow emits an energetic beam parallel to the axis of rotation. According to the simplest picture, all GRBs

  18. THE JOINT ESA-NASA EUROPA JUPITER SYSTEM MISSION (EJSM)

    NASA Astrophysics Data System (ADS)

    Lebreton, J.; Pappalardo, R. T.; Blanc, M.; Bunce, E. J.; Dougherty, M. K.; Erd, C.; Grasset, O.; Greeley, R.; Johnson, T. V.; Clark, K. B.; Prockter, L. M.; Senske, D. A.

    2009-12-01

    The joint "Europa Jupiter System Mission" (EJSM) is an international mission under study in collaboration between NASA and ESA. Its goal is to study Jupiter and its magnetosphere, the diversity of the Galilean satellites, the physical characteristics, composition and geology of their surfaces. Europa and Ganymede are two primary targets of the mission. The reference mission architecture consists of the NASA-led Jupiter Europa Orbiter (JEO) and the ESA-led Jupiter Ganymede Orbiter (JGO). The two primary goals of the mission are i) to determine whether the Jupiter system harbors habitable worlds and ii) to characterize the processes within the Jupiter system. The science objectives addressing the first goal are to: i) characterize and determine the extent of subsurface oceans and their relations to the deeper interior, ii) characterize the ice shells and any subsurface water, including the heterogeneity of the ice, and the nature of surface-ice-ocean exchange; iii) characterize the deep internal structure, differentiation history, and (for Ganymede) the intrinsic magnetic field; iv) compare the exospheres, plasma environments, and magnetospheric interactions; v) determine global surface composition and chemistry, especially as related to habitability; vi) understand the formation of surface features, including sites of recent or current activity, and identify and characterize candidate sites for future in situ exploration. The science objectives for addressing the second goal are to: i) understand the Jovian satellite system, especially as context for Europa and Ganymede; ii) evaluate the structure and dynamics of the Jovian atmosphere; iii) characterize processes of the Jovian magnetodisk/magnetosphere; iv) determine the interactions occurring in the Jovian system; and v) constrain models for the origin of the Jupiter system. Both spacecraft would carry a complement of 11-12 instruments launch separately in 2020 and use a Venus-Earth-Earth Gravity Assist (VEEGA

  19. Status of the ESA Meteosat Second Generation (MSG) Programme

    NASA Astrophysics Data System (ADS)

    Stark, H. R.; Schumann, W.

    2004-11-01

    Following on from the first generation of Meteosat, the Meteosat Second Generation (MSG) programme promises to provide advanced and more frequent data for short-range and medium-range weather forecasting and climate monitoring for at least the next 12 years. The MSG programme is a cooperation between ESA and EUMETSAT, the European Organisation for the Exploitation of Meteorological Satellites organisation. ESA has been responsible for designing and developing the first of the four satellites in the MSG programme, whilst EUMETSAT has overall responsibility for defining the end-user requirements, developing the ground segment and operating the system. The first MSG satellite, called MSG-1 (METEOSAT 8), was successfully launched on 28August 2002 by an Ariane 5 launcher together with its co-passenger Atlantic Bird. ESOC took over control of the satellite after separation and placed the satellite from the Ariane injection orbit to a quasi-geostationary orbit drifting slowly towards the commissioning longitude at 10.5 deg West. Subsequently EUMETSAT started the satellite commissioning testing. Except the in-orbit failure of an on-board amplifier, with its consequences for the dissemination service, the achieved results show a high degree of compliance with respect to the satellite specification and show very good overall performance of the satellite, in particular for the Spinning Enhanced Visible and Infrared Imager (SEVIRI) instrument to be outstanding. METEOSAT-8 entered routine operations on 29 January 2004. In parallel with the MSG-1 commissioning activities, the integration and test phases on the other MSG satellites has well progressed. Begin March 2004, EUMETSAT took the decision to take the MSG-2 satellite out of storage, resuming testing and work on it towards its final preparation for launch with a launch period now defined between February and April 2005. MSG-3 is entered into storage in summer this year. It is an intermediate storage configuration, after the

  20. TROPOMI on ESA's Sentinel 5p ready for launch and use

    NASA Astrophysics Data System (ADS)

    de Vries, Johan; Voors, Robert; Ording, Barend; Dingjan, Jos; Veefkind, Pepijn; Ludewig, Antje; Kleipool, Quintus; Hoogeveen, Ruud; Aben, Ilse

    2016-08-01

    TROPOMI is the single instrument on ESA's Sentinel 5 precursor satellite to be launched in October 2016. TROPOMI will measure the atmospheric constituents absorbing in the UV-SWIR wavelength range, being O3, NO2, SO2, CH4, CO, CH2O, and aerosol properties. TROPOMI is a sun back-scatter instrument in the line of SCIAMACHY and OMI with 4 spectrometer bands and a spectral resolution of 0.25 - 0.5 nm. Following the earlier sensors, firstly the spatial resolution is improved by a factor 6 (OMI) to 7 x 7 km2 and at the same time the sensitivity by an order of magnitude. The paper discusses the instrument performances as acquired from on-ground performance / calibration measurements. For the calibration an extremely condensed measurement campaign of 4 months 24/7 measurements was performed with virtually no slack and still gathering all of the data necessary from on-ground measurements. Given the fact that the trace gas signals and their variation in the measured spectra can be quite small, calibration is crucial to get accurate results and this illustrates that TROPOMI is a highly success driven and efficient programme. TROPOMI / Sentinel-5p bridges the data streams from on one hand OMI and SCIAMACHY and on the other hand the future Sentinel-5. It is the first of a series of satellites from the Copernicus programme devoted to air quality and will soon be ready for use.

  1. Ultraviolet absorption spectrum of HOCl

    NASA Technical Reports Server (NTRS)

    Burkholder, James B.

    1993-01-01

    The room temperature UV absorption spectrum of HOCl was measured over the wavelength range 200 to 380 nm with a diode array spectrometer. The absorption spectrum was identified from UV absorption spectra recorded following UV photolysis of equilibrium mixtures of Cl2O/H2O/HOCl. The HOCl spectrum is continuous with a maximum at 242 nm and a secondary peak at 304 nm. The measured absorption cross section at 242 nm was (2.1 +/- 0.3) x 10 exp -19/sq cm (2 sigma error limits). These results are in excellent agreement with the work of Knauth et al. (1979) but in poor agreement with the more recent measurements of Mishalanie et al. (1986) and Permien et al. (1988). An HOCl nu2 infrared band intensity of 230 +/- 35/sq cm atm was determined based on this UV absorption cross section. The present results are compared with these previous measurements and the discrepancies are discussed.

  2. Transition Energies and Absorption Oscillator Strengths for {{c}_{4}}^{\\prime 1}{{{\\rm{\\Sigma }}}_{u}}^{+}-{{\\rm{X}}}^{1}{{{\\rm{\\Sigma }}}_{g}}^{+}, {b}^{\\prime 1}{{{\\rm{\\Sigma }}}_{u}}^{+}-{{\\rm{X}}}^{1}{{{\\rm{\\Sigma }}}_{g}}^{+}, and {{c}_{5}}^{\\prime 1}{{{\\rm{\\Sigma }}}_{u}}^{+}-{{\\rm{X}}}^{1}{{{\\rm{\\Sigma }}}_{g}}^{+} Band Systems in N2

    NASA Astrophysics Data System (ADS)

    Lavín, C.; Velasco, A. M.

    2017-04-01

    Theoretical transition energies and absorption oscillator strengths for the {{c}4}\\prime 1{{{{Σ }}}u}+ (v‧ = 0–2, 5, 7, 8) ‑ {{{X}}}1{{{{Σ }}}g}+(v\\prime\\prime =0{--}14) and {{c}5}\\prime 1{{{{Σ }}}u}+ (v‧ = 0, 2) ‑ {{{X}}}1{{{{Σ }}}g}+ (v″ = 0–14) Rydberg bands, and {b}\\prime 1{{{{Σ }}}u}+ (v‧ = 0–9, 11, 12, 14–19, 21, 22) ‑ {{{X}}}1{{{{Σ }}}g}+ (v″ = 0–14) valence bands of molecular nitrogen are reported. The strong interaction between {}1{{{{Σ }}}u}+ states has been dealt with through a vibronic interaction matrix. As a consequence of the Rydberg-valence interaction, irregularities in the vibrational structure of the above band systems are observed. Good agreement is found with the scarce high-resolution data that are available for oscillator strengths. The new band oscillator strengths reported here may be useful for a reliable interpretation of the spectra from atmospheres of the Earth, Titan, and Triton, where {{{N}}}2 is the mayor constituent.

  3. M⁴ - a mission candidate for ESA M4

    NASA Astrophysics Data System (ADS)

    Retino, A.; Vaivads, A.

    2014-12-01

    We present a mission concept that will be proposed in the response to the upcoming ESA M4 Call. The working name of the mission is M⁴. The scientific theme of the M⁴ mission is turbulent energy dissipation and particle energization. The main focus is on turbulence and shock processes, however areas where the different fundamental processes interact, such as reconnection in turbulence or shock generated turbulence, is also of high importance. The M⁴ mission aims to address such fundamental questions as how energy is dissipated at kinetic scales, how energy is partitioned among different plasma components, what is the relative importance of waves and coherent structures in the dissipation processes. To reach the goal a careful design work of the M⁴ mission and its payload has been done and it is based on the earlier mission concepts of Tor, EIDOSCOPE and Cross-Scale. We present the basic concepts of the M⁴ mission and its payload as well as illustrate how it will help to address the science questions posed.

  4. Research recommendations of the ESA Topical Team on Artificial Gravity

    NASA Astrophysics Data System (ADS)

    Clément, Gilles; Bukley, Angie

    Many experts believe that artificial gravity will be required for an interplanetary mission. However, despite its attractiveness as an efficient, multi-system countermeasure and its potential for simplifying operational activities, much still needs to be learned regarding the human response to rotating environments before artificial gravity can be successfully implemented. The European Space Agency (ESA) Topical Team on Artificial Gravity recommended a comprehensive program to determine the gravity threshold required to reverse or prevent the detrimental effects of microgravity and to evaluate the effects of centrifugation on various physiological functions. Part of the required research can be accomplished using animal models on a dedicated centrifuge in low Earth orbit. Studies of human responses to centrifugation could be performed during ambulatory, short- and long-duration bed rest, and in-flight studies. Artificial-gravity scenarios should not be a priori discarded in Moon and Mars mission designs. One major step is to determine the relationship between the artificial gravity dose level, duration, and frequency and the physiological responses of the major body functions affected by spaceflight. Once its regime characteristics are defined and a dose-response curve is established, artificial gravity should serve as the standard against which all other countermeasure candidates are evaluated, first on Earth and then in space.

  5. Operational Experience with Autonomous Star Trackers on ESA Interplanetary Spacecraft

    NASA Technical Reports Server (NTRS)

    Lauer, Mathias; Jauregui, Libe; Kielbassa, Sabine

    2007-01-01

    Mars Express (MEX), Rosetta and Venus Express (VEX) are ESA interplanetary spacecrafts (S/C) launched in June 2003, March 2004 and November 2005, respectively. Mars Express was injected into Mars orbit end of 2003 with routine operations starting in spring 2004. Rosetta is since launch on its way to rendezvous comet Churyumov-Gerasimenko in 2014. It has completed several test and commissioning activities and is performing several planetary swingbys (Earth in spring 2005, Mars in spring 2007, Earth in autumn 2007 and again two years later). Venus Express has also started routine operations since the completion of the Venus orbit insertion maneuver sequence beginning of May 2006. All three S/C are three axes stabilized with a similar attitude and orbit control system (AOCS). The attitude is estimated on board using star and rate sensors and controlled using four reaction wheels. A bipropellant reaction control system with 10N thrusters serves for wheel off loadings and attitude control in safe mode. Mars Express and Venus Express have an additional 400N engine for the planetary orbit insertion. Nominal Earth communication is accomplished through a high gain antenna. All three S/C are equipped with a redundant set of autonomous star trackers (STR) which are based on almost the same hardware. The STR software is especially adapted for the respective mission. This paper addresses several topics related to the experience gained with the STR operations on board the three S/C so far.

  6. ESA's new European Hubble Science Archive at ESAC

    NASA Astrophysics Data System (ADS)

    Baines, Deborah

    2015-12-01

    ESA's European Space Astronomy Centre (ESAC) has recently launched a new version of the European Hubble Space Telescope science archive. The new and enhanced archive offers several new features, some of which are not available anywhere else. The new web-based archive has been completely re-engineered and is now faster, more accurate and more robust than ever. Several of its unique features will be presented: the possibility of seeing the exact footprint of each observations on top of an optical all-sky image, the online visualization and inspection of FITS headers, imaging and spectral observation previews without downloading files or the possibility to search for data that has not yet been published in refereed journals. This state-of-the-art science data archive will be the new main access point to HST data for the European astronomical community and will be enhanced in the near-future to include the Hubble Source Catalogue or other high-level data products as required.

  7. ESA hardware for plant research on the International Space Station

    NASA Astrophysics Data System (ADS)

    Brinckmann, E.

    The long awaited launch of the European Modular Cultivation System (EMCS) will provide a platform on which long-term and shorter experiments with plants will be performed on the International Space Station (ISS). EMCS is equipped with two centrifuge rotors (600 mm diameter), which can be used for in-flight 1 g controls and for studies with acceleration levels from 0.001 g to 2.0 g. Several experiments are in preparation investigating gravity relating to gene expression, gravisensing and phototropism of Arabidopsis thaliana and lentil roots. The experiment-specific hardware provides growth chambers for seedlings and whole A. thaliana plants and is connected to the EMCS Life Support System. Besides in-flight video observation, the experiments will be evaluated post-flight by means of fixed or frozen material. EMCS will have for the first time the possibility to fix samples on the rotating centrifuge, allowing a detailed analysis of the process of gravisensing. About two years after the EMCS launch, ESA's Biolab will be launched in the European "Columbus" Module. In a similar way as in EMCS, Biolab will accommodate experiments with plant seedlings and automatic fixation processes on the centrifuge. The hardware concepts for these experiments are presented in this communication.

  8. ESA sees stardust storms heading for Solar System

    NASA Astrophysics Data System (ADS)

    2003-08-01

    The Sun's galactic environment Credits: P.C. Frisch, University of Chicago The Sun's galactic environment The Sun and the nearest stars move through filaments of galactic clouds. Ulysses and the heliosphere hi-res Size hi-res: 1337 kb Credits: ESA (image by D. Hardy) Ulysses and the heliosphere Over more than 17 years of observations above and below the poles of the Sun, the ESA/NASA Ulysses mission has made fundamental contributions to our understanding of the Sun itself, its sphere of influence (the heliosphere), and our local interstellar neighbourhood. The mission provided the first-ever map of the heliosphere in the four dimensions of space and time. Ulysses was launched by Space Shuttle Discovery in October 1990. It headed out to Jupiter, arriving in February 1992 for the gravity-assist manoeuvre that swung the craft into its unique solar orbit. It orbited the Sun three times and performed six polar passes. The mission concludes on 1 July 2008. Since its launch in 1990, Ulysses has constantly monitored how much stardust enters the Solar System from the interstellar space around it. Using an on-board instrument called DUST, scientists have discovered that stardust can actually approach the Earth and other planets, but its flow is governed by the Sun's magnetic field, which behaves as a powerful gate-keeper bouncing most of it back. However, during solar maximum - a phase of intense activity inside the Sun that marks the end of each 11-year solar cycle - the magnetic field becomes disordered as its polarity reverses. As a result, the Sun's shielding power weakens and more stardust can sneak in. What is surprising in this new Ulysses discovery is that the amount of stardust has continued to increase even after the solar activity calmed down and the magnetic field resumed its ordered shape in 2001. Scientists believe that this is due to the way in which the polarity changed during solar maximum. Instead of reversing completely, flipping north to south, the Sun

  9. ESA scientist discovers a way to shortlist stars that might have planets

    NASA Astrophysics Data System (ADS)

    2002-02-01

    Traces of the disc surrounding our Solar System Credits: Michael Hauser (Space Telescope Science Institute), the COBE/DIRBE Science Team, and NASA Traces of the disc surrounding our Solar System Traces of the disc surrounding our Solar System. The blue band curving across this image is created by the dust disc surrounding our Solar System. Viewed from afar this would show up as a bright ring surrounding the Sun. The bright band running across the centre of the image is from dust in our Galaxy. This image, taken by the COBE satellite, is a composite of three far-infrared wavelengths (60, 100, and 240 microns). (Photo: Michael Hauser (Space Telescope Science Institute), the COBE/DIRBE Science Team, and NASA) Disc surrounding the Sun Credits: Brad Smith (University of Hawaii), Glenn Schneider (University of Arizona), and NASA Viewed from afar our Solar System would have a bright disc surrounding the Sun Viewed from afar our Solar System would have a bright dust disc surrounding the Sun similar to the disc surrounding this star. This image, taken with Hubble's Near Infrared Camera and Multi-Object Spectrometer (NICMOS), shows a dust ring around a star called HR 4796A. The image was taken on March 15, 1998. (Photo: Brad Smith (University of Hawaii), Glenn Schneider (University of Arizona), and NASA) Ulysses in flight configuration hi-res Size hi-res: 117 Kb Credits: ESA/Dave Hardy Ulysses at Jupiter encounter Ulysses in flight configuration passing by Jupiter. Remarkably, their discovery gives astronomers a way to determine which other stars in the Galaxy are most likely to harbour planets and allows mission planners to draw up a 'short-list' of stars to be observed by ESA's future planet-search missions, Eddington and Darwin. The discovery of the Solar System's dust ring strengthens the idea that such features around mature stars are signposts to planetary systems. The reason for this is that planetary systems are thought to condense from a cloud of gas and dust

  10. Absorption of CO laser radiation by NO

    NASA Technical Reports Server (NTRS)

    Hanson, R. K.; Monat, J. P.; Kruger, C. H.

    1976-01-01

    The paper describes absorption calculations and measurements at selected infrared CO laser wavelengths which are nearly coincident with absorption lines in the fundamental vibration-rotation band of NO near 5.3 microns. Initial work was directed towards establishing the optimal CO laser-NO absorption line coincidence for high temperature applications. Measurements of the absorption coefficient at this optimal laser wavelength were carried out, first using a room-temperature absorption cell for high-temperature calculations and then using a shock tube, for the temperature range 630-4000 K, to validate the high temperature calculations.

  11. The ESA Lunar Lander and the search for Lunar Volatiles

    NASA Astrophysics Data System (ADS)

    Morse, A. D.; Barber, S. J.; Pillinger, J. M.; Sheridan, S.; Wright, I. P.; Gibson, E. K.; Merrifield, J. A.; Waltham, N. R.; Waugh, L. J.; Pillinger, C. T.

    2011-10-01

    Following the Apollo era the moon was considered a volatile poor body. Samples collected from the Apollo missions contained only ppm levels of water formed by the interaction of the solar wind with the lunar regolith [1]. However more recent orbiter observations have indicated that water may exist as water ice in cold polar regions buried within craters at concentrations of a few wt. % [2]. Infrared images from M3 on Chandrayaan-1 have been interpreted as showing the presence of hydrated surface minerals with the ongoing hydroxyl/water process feeding cold polar traps. This has been supported by observation of ephemeral features termed "space dew" [3]. Meanwhile laboratory studies indicate that water could be present in appreciable quantities in lunar rocks [4] and could also have a cometary source [5]. The presence of sufficient quantities of volatiles could provide a resource which would simplify logistics for long term lunar missions. The European Space Agency (ESA's Directorate of Human Spaceflight and Operations) have provisionally scheduled a robotic mission to demonstrate key technologies to enable later human exploration. Planned for launch in 2018, the primary aim is for precise automated landing, with hazard avoidance, in zones which are almost constantly illuminated (e.g. at the edge of the Shackleton crater at the lunar south pole). These regions would enable the solar powered Lander to survive for long periods > 6 months, but require accurate navigation to within 200m. Although landing in an illuminated area, these regions are close to permanently shadowed volatile rich regions and the analysis of volatiles is a major science objective of the mission. The straw man payload includes provision for a Lunar Volatile and Resources Analysis Package (LVRAP). The authors have been commissioned by ESA to conduct an evaluation of possible technologies to be included in L-VRAP which can be included within the Lander payload. Scientific aims are to demonstrate the

  12. ESA chairs the International Living With a Star programme

    NASA Astrophysics Data System (ADS)

    2003-02-01

    The Sun is a variable star. The amount of radiation it releases changes constantly, especially at wavelengths that we cannot see, such as ultraviolet. It also releases a stormy ‘wind’ of particles known as the solar wind that buffets the Earth’s magnetic field. Sudden changes in the solar wind can disable communications satellites, disrupt power stations on Earth, and affect passengers in high-flying aircraft. Slow variation in the solar output and even in the solar wind could contribute to climatic changes. Knowing more about these phenomena is therefore very important in different and sometimes unexpected ways. There will be various ILWS mission launches over an approximately ten-year period, starting in 2003. Pooling the resources of the largest fleet of spacecraft in history, the ILWS programme will provide a first global view of the Sun-Earth interaction and lead to a real understanding of it. It will look at the Sun’s effects on other planets also. ESA’s missions form a vital part of ILWS. SOHO and Cluster are leading the way. In 2003, in collaboration with China, a space mission called Double Star will be launched to complement Cluster. In a decade’s time, ESA’s Solar Orbiter will be the centre of interest. It will go closer to the Sun than any solar mission ever before. In between, ESA will assist in exploiting other agency’s missions to the full; it is also currently negotiating to provide ground stations for Japan’s Solar-B mission (launch 2005), and is considering the part it may play in NASA’s STEREO (launch 2005) and Solar Dynamics Orbiter (launch 2007) missions. In addition, ESA’s missions to the other terrestrial planets, Mars Express (launching 2003), Venus Express (launching 2005), and the mission to Mercury, BepiColombo (launching 2011/2012), will carry experiments that look at solar-wind interactions with their respective planets. Hermann Opgenoorth, ESA’s newly appointed Head of Solar and Solar-Terrestrial Missions, is

  13. The 2009 ESA/Danish Mars Simulation Wind Tunnel Facility

    NASA Astrophysics Data System (ADS)

    Nornberg, P.; Merrison, J. P.; Gunnlaugsson, H. P.

    2009-04-01

    Simulation of the dynamic environment in immediate proximity to the surface of Mars requires access to simulation facilities which can reproduce the atmospheric properties (pressure, temperature, gas composition, UV-VIS light conditions, wind flow etc.). It also requires access to analogue Martian surface material (soil and dust). Simulations can be carried out in a wind tunnel placed in a tank which can be pumped out, like the 400 mm Ø, 1500 mm long wind tunnel that has operated in the Mars Simulation Laboratory at University of Aarhus, Denmark since 2000 (1). A wide range of applications have taken place, from development, test and calibration of instruments, over tests of solar panels, and aerodynamic studies of granular transport to studies of physical properties of dust materials such as grain electrification, aggregation and magnetic properties (2,3). The Salten Skov I analogue (4) and other Martian regolits and dust analogues have been used in the wind tunnel experiments. With the view to future instrument development, solar panel optimization and future research on Martian surface processes a new ESA supported wind tunnel has been constructed at University of Aarhus, Denmark and is now under building. This wind tunnel will have a cross section of close to 1 x 2 m and be able to reach a wind speed of close to 30 m/s under Martian pressure conditions and with samples cooled down to Martian temperatures. The facility is planned to be finally tested and ready for use in July 2009. ESA, ExoMars use of this facility will have priority. However, research projects in collaboration with external users will also be welcome in the future. Later this year information on access possibilities will be announced at the Mars Simulation Laboratory home page: www.marslab.dk. References: (1) Merrison, J., Bertelsen, P., Frandsen, C., Gunnlaugsson, H.P., Knudsen, J.M., Madsen, M.B., Mossin, L., Nielsen, J., Nørnberg, P., Rasmussen, K.R., Uggerhøj, E. and Weyer, G. 2002

  14. Rosetta performs ESA's closest-ever Earth fly-by

    NASA Astrophysics Data System (ADS)

    2005-03-01

    Rosetta’s unique instruments, such as its ultraviolet light instrument ALICE, should be able to make critical contributions to the American mission. About Rosetta Rosetta is the first mission designed to both orbit and land on a comet, and consists of an orbiter and a lander. The spacecraft carries 11 scientific experiments and will be the first mission to undertake long-term exploration of a comet at close quarters. After entering orbit around Comet 67P/Churyumov-Gerasimenko in 2014, the spacecraft will release a small lander onto the icy nucleus. Rosetta will orbit the comet for about a year as it heads towards the Sun, remaining in orbit for another half-year past perihelion (closest approach to the Sun). Comets hold essential information about the origin of our Solar System because they are the most primitive objects in the Solar System and their chemical composition has changed little since their formation. By orbiting and landing on Comet 67P/Churyumov-Gerasimenko, Rosetta will help us reconstruct the history of our own neighbourhood in space. Note for broadcasters: The ESA TV Service will transmit a TV exchange with images of the fly-by, together with science results/images from observations as far as available on 11 March. For further details : http://television.esa.int

  15. Laparoscopic gastric banding

    MedlinePlus

    ... adjustable gastric banding; Bariatric surgery - laparoscopic gastric banding; Obesity - gastric banding; Weight loss - gastric banding ... gastric banding is not a "quick fix" for obesity. It will greatly change your lifestyle. You must ...

  16. The ESA Virtual Space Weather Modelling Centre - Phase 1

    NASA Astrophysics Data System (ADS)

    Poedts, Stefaan

    The ESA ITT project (AO/1-6738/11/NL/AT) to develop Phase 1 of a Virtual Space Weather Modelling Centre has the following objectives and scope: 1. The construction of a long term (~10 yrs) plan for the future development of a European virtual space weather modelling centre consisting of a new ‘open’ and distributed framework for the coupling of physics based models for space weather phenomena; 2. The assessment of model capabilities and the amount of work required to make them operational by integrating them in this framework and the identification of computing and networking requirements to do so. 3. The design of a system to enable models and other components to be installed locally or geographically distributed and the creation of a validation plan including a system of metrics for testing results. The consortium that took up this challenge involves: 1)the Katholieke Universiteit Leuven (Prime Contractor, coordinator: Prof. S. Poedts); 2) the Belgian Institute for Space Aeronomy (BIRA-IASB); 3) the Royal Observatory of Belgium (ROB); 4) the Von Karman Institute (VKI); 5) DH Consultancy (DHC); 6) Space Applications Services (SAS). The project started on May 14 2012, and will finish in May 2014. Thus, by the time of the meeting, both Phase 1A and Phase 1B (the development of the prototype) will be finished. The final report will be presented incl. the architecture decisions made, the framework, the current models integrated already as well as the model couplers installed. The prototype VSWMC will be demonstrated.

  17. An ESA roadmap for geobiology in space exploration

    NASA Astrophysics Data System (ADS)

    Cousins, Claire R.; Cockell, Charles S.

    2016-01-01

    Geobiology, and in particular mineral-microbe interactions, has a significant role to play in current and future space exploration. This includes the search for biosignatures in extraterrestrial environments, and the human exploration of space. Microorganisms can be exploited to advance such exploration, such as through biomining, maintenance of life-support systems, and testing of life-detection instrumentation. In view of these potential applications, a European Space Agency (ESA) Topical Team "Geobiology in Space Exploration" was developed to explore these applications, and identify research avenues to be investigated to support this endeavour. Through community workshops, a roadmap was produced, with which to define future research directions via a set of 15 recommendations spanning three key areas: Science, Technology, and Community. These roadmap recommendations identify the need for research into: (1) new terrestrial space-analogue environments; (2) community level microbial-mineral interactions; (3) response of biofilms to the space environment; (4) enzymatic and biochemical mineral interaction; (5) technical refinement of instrumentation for space-based microbiology experiments, including precursor flight tests; (6) integration of existing ground-based planetary simulation facilities; (7) integration of fieldsite biogeography with laboratory- and field-based research; (8) modification of existing planetary instruments for new geobiological investigations; (9) development of in situ sample preparation techniques; (10) miniaturisation of existing analytical methods, such as DNA sequencing technology; (11) new sensor technology to analyse chemical interaction in small volume samples; (12) development of reusable Lunar and Near Earth Object experimental platforms; (13) utility of Earth-based research to enable the realistic pursuit of extraterrestrial biosignatures; (14) terrestrial benefits and technological spin-off from existing and future space

  18. ESA' s novel gravitational modeling of irregular planetary bodies

    NASA Astrophysics Data System (ADS)

    Ortega, Guillermo

    A detailed understanding and modeling of the gravitational modeling is required for realistic investigation of the dynamics of orbits close to irregularly shaped bodies. Gravity field modelling up to a certain maximum spherical harmonic degree N involves N2 unkown spherical harmonic coefficients or complex harmonics. The corresponding number of matrix entries reaches till N4 . For missions like CHAMP, GRACE or GOCE, the maximum degree of resolution is 75, 150 and 300 respectively. Therefore, the number of unknowns for a satellite like GOCE will be around 100.000. Since these missions usually fly for a period of time of several years, the number of observations is huge. Hence, gravity field recovery from these missions is a high demanding task. The classical approaches like spherical expansion of the potential lead generally to a high number of coefficients, which reduce the software computational efficiency of the orbit propagation and which have mostly a limited physical meaning. One of the main targets of the activity is the modelling of asteroids, small moons, and cometary bodies. All celestial bodies are irregular by definition. However, the scope of the activity is broad enough as to be able to use the models and the software in quasy-regular bodies as well. Therefore the models and tools could be used for bodies such as the Moon, Mars, Venus, Deimos, Europa, Eros, Mathilda, and Churyumov-Gerasimenko, etc., being these applications relevant for scientific (Rosetta, Bepi Colombo), exploration (Exo-Mars), NEO mitigation (Don Quijote) and Earth observation (GOCE) missions of ESA.

  19. ESA's new view of the Milky Way - in gamma rays!

    NASA Astrophysics Data System (ADS)

    2003-11-01

    Integral's gamma-ray map of the galaxy hi-res Size hi-res: 430 kb Credits: ESA/SPI team A portion of Integral's gamma-ray map of the galaxy A portion of Integral's gamma-ray map of the galaxy. This false colour picture was taken by the spectrometer on board Integral (SPI) between December 2002 and March 2003. The yellow dots correspond to bright known gamma-rays sources, whilst blue areas indicate regions of low emission. Data similar to these, but in a higher energy range, have been used to study where aluminium and iron are produced in the Galaxy. Since its formation from a cloud of hydrogen and helium gas, around 12 000 million years ago, the Milky Way has gradually been enriched with heavier chemical elements. This has allowed planets and, indeed, life on Earth to form. Today, one of those heavier elements - radioactive aluminium - is spread throughout the Galaxy and, as it decays into magnesium, gives out gamma rays with a wavelength known as the '1809 keV line'. Integral has been mapping this emission with the aim of understanding exactly what is producing all this aluminium. In particular, Integral is looking at the aluminium 'hot spots' that dot the Galaxy to determine whether these are caused by individual celestial objects or the chance alignment of many objects. Astronomers believe that the most likely sources of the aluminium are supernovae (exploding high-mass stars) and, since the decay time of the aluminium is around one million years, Integral's map shows how many stars have died in recent celestial history. Other possible sources of the aluminium include 'red giant' stars or hot blue stars that give out the element naturally. To decide between these options, Integral is also mapping radioactive iron, which is only produced in supernovae. Theories suggest that, during a supernova blast, aluminium and iron should be produced together in the same region of the exploding star. Thus, if the iron's distribution coincides with that of the aluminium, it

  20. ESA NEOCC effort to eliminate high Palermo Scale virtual impactors

    NASA Astrophysics Data System (ADS)

    Micheli, M.; Koschny, D.; Hainaut, O.; Bernardi, F.

    2014-07-01

    At the moment of this writing about 4 % of the known near-Earth objects are known to have at least one future close approach scenario with a non-negligible collision probability within the next century, as routinely computed by the NEODyS and Sentry systems. The most straightforward way to improve the knowledge of the future dynamics of an NEO in order to exclude (or possibly confirm) some of these possible future impact is to obtain additional astrometric observations of the object as soon as it becomes observable again. In particular, since a large fraction (>98 %) of the known objects currently recognized as possible future impactors have been observed during a single opposition, this usually corresponds to obtaining a new set of observations during a second opposition, a so called ''recovery''. However, in some cases the future observability windows for the target after the discovery apparition may be very limited, either because the object is intrinsically small (and therefore requires a very close and consequently rare approach to become observable) or because its orbital dynamic prevents the observability from the ground for a long timespan (as in the case of quasi-resonant objects with a long synodic period). When this happens, the only short-term way to clarify an impact scenario is to look toward the past, and investigate the possibility that unrecognized detections of the object are already present in the databases of old astronomical images, which are often archived by professional telescopes and made available to the community a few months to years after they are exposed. We will here present an effort lead by the newly formed ESA NEO Coordination Centre (NEOCC) in Frascati to pursue both these avenues with the intent of improving the orbital knowledge of the highest-rated possible impactors, as defined by the Palermo Technical Impact Hazard Scale (PS in the following). As an example of our ongoing observational activities, we will first present our

  1. PERITONEAL ABSORPTION

    PubMed Central

    Hahn, P. F.; Miller, L. L.; Robscheit-Robbins, F. S.; Bale, W. F.; Whipple, G. H.

    1944-01-01

    The absorption of red cells from the normal peritoneum of the dog can be demonstrated by means of red cells labeled with radio-iron incorporated in the hemoglobin of these red cells. Absorption in normal dogs runs from 20 to 100 per cent of the amount given within 24 hours. Dogs rendered anemic by bleeding absorb red cells a little less rapidly—ranging from 5 to 80 per cent of the injected red cells. Doubly depleted dogs (anemic and hypoproteinemic) absorb even less in the three experiments recorded. This peritoneal absorption varies widely in different dogs and even in the same dog at different times. We do not know the factors responsible for these variations but there is no question about active peritoneal absorption. The intact red cells pass readily from the peritoneal cavity into lymph spaces in diaphragm and other areas of the peritoneum. The red cells move along the lymphatics and through the lymph glands with little or no phagocytosis and eventually into the large veins through the thoracic ducts. PMID:19871404

  2. Nutrient absorption.

    PubMed

    Rubin, Deborah C

    2004-03-01

    Our understanding of nutrient absorption continues to grow, from the development of unique animal models and from studies in which cutting-edge molecular and cellular biologic approaches have been used to analyze the structure and function of relevant molecules. Studies of the molecular genetics of inherited disorders have also provided many new insights into these processes. A major advance in lipid absorption has been the cloning and characterization of several intestinal acyl CoA:monoacylglycerol acyltransferases; these may provide new targets for antiobesity drug therapy. Studies of intestinal cholesterol absorption and reverse cholesterol transport have encouraged the development of novel potential treatments for hyperlipidemia. Observations in genetically modified mice and in humans with mutations in glucose transporter 2 suggest the importance of a separate microsomal membrane transport pathway for glucose transport. The study of iron metabolism has advanced greatly with the identification of the hemochromatosis gene and the continued examination of the genetic regulation of iron absorptive pathways. Several human thiamine transporters have been identified, and their specific roles in different tissues are being explored.

  3. Infrared laser absorption spectroscopy of the nu4 (sigma u) fundamental and associated nu11(pi u) hot band of C7 - Evidence for alternating rigidity in linear carbon clusters

    NASA Technical Reports Server (NTRS)

    Heath, J. R.; Saykally, R. J.

    1991-01-01

    The first characterization of the bending potential of the C7 cluster is reported via the observation of the v = 1(1) and v = 2 deg levels of the nu11 (pi u) bend as hot bands associated with the nu4 (sigma u) antisymmetric stretch fundamental. The lower state hot band rotational constants are measured to be 1004.4(1.3) and 1123.6(9.0) MHz, constituting a 9.3 and 22 percent increase over the ground state rotational constant, 918.89 (41) MHz. These large increases are strong quartic and sextic centrifugal distortion constants determined for the ground and nu 4 = 1 states are found to be anomalously large and negative, evidencing strong perturbations between stretching and bending modes.

  4. Full load of ESA experiments on Maxus-2 sounding rocket

    NASA Astrophysics Data System (ADS)

    1995-11-01

    Maxus sounding rockets are built and commercialised by an industrial joint venture, a team comprising of the Swedish Space Corporation (SSC) and DASA of Germany. ESA is fully funding the scientific payload for this mission. The payload comprises 8 experiments spanning the fields of fluid physics, electrophoresis and cell biology. Scientists from Belgium, France, Germany and Switzerland designed these experiments and the hardware was built by Swedish, German and Italian firms. The experiments are accommodated in 5 autonomous experiment modules and account for an overall mass of about 500 kg out of a total payload of about 800 kg. The first module contains an experiment which aims to check the static and dynamic behaviour of liquids at corners and edges. The second contains a biological experiment on two unicellular organisms (loxodes and paramecium). In their natural habitat (lakes), these organisms make use of the gravity vector for their orientation. Their swimming behaviour in microgravity will be observed on Earth in real time. The third module houses two other biology experiments. One examines the effect of microgravity on particle ingestion of gold beads by human macrophage cells (a type of white blood cell). Macrophage cells digest foreign particles, such as bacteria and viruses, thereby performing an important function in our immune system. The other experiment investigates the influence of weightlessness on the structure of lymphocytes (white blood cells). The fourth module accommodates three different experiments all dealing with convection phenomena due to surface-tension instabilities (Marangoni convection). Surface tension is that property of liquids which makes raindrops nearly spherical and allows insects to move on water surfaces. These phenomena, which are masked by the effect of gravity on Earth, can be easily studied in microgravity conditions. The fifth module contains an experiment that deals with electrophoresis, i.e. a process which is used to

  5. Selective coherent perfect absorption in metamaterials

    SciTech Connect

    Nie, Guangyu; Shi, Quanchao; Zhu, Zheng; Shi, Jinhui

    2014-11-17

    We show multi-band coherent perfect absorption (CPA) in simple bilayered asymmetrically split ring metamaterials. The selectivity of absorption can be accomplished by separately excited electric and magnetic modes in a standing wave formed by two coherent counterpropagating beams. In particular, each CPA can be completely switched on/off by the phase of a second coherent wave. We propose a practical scheme for realizing multi-band coherent perfect absorption of 100% that is allowed to work from microwave to optical frequency.

  6. Predissociation linewidths of the (3,0)-(11,0) Schumann-Runge absorption bands of (O-18)2 and O-16O-18 in the wavelength region 180-196 nm

    NASA Technical Reports Server (NTRS)

    Chiu, S. S.-L.; Cheung, A. S.-C.; Yoshino, K.; Esmond, J. R.; Freeman, D. E.

    1990-01-01

    The Yoshino et al. (1988) measurements of absolute cross sections and those of Cheung et al. (1988) for spectroscopic constants are presently used to derive the predissociation linewidths of the (3,0)-(11,0) Schumman-Runge bands of (O-18)2 and O-16O-18, in the 180-196 nm wavelength region. Linewidths are determined as parameters in the nonlinear, least-squares fitting of calculated cross-sections to measured ones. The predissociation linewidths obtained are noted to often be greater than previously obtained experimental values for both isotopic molecules.

  7. ESA's Hipparcos satellite revises the scale of the cosmos

    NASA Astrophysics Data System (ADS)

    1997-02-01

    Sun, called parallaxes, give the first direct measurements of the distances of large numbers of stars. With the overall calculations completed, the harvest of scientific discoveries has begun. Among those delighted with the immediate irruption into cosmology, from this spacecraft made in Europe, is ESA's director of science, Roger Bonnet. "When supporters of the Hipparcos project argued their case," Bonnet recalls, "they were competing with astrophysical missions with more obvious glamour. But they promised remarkable consequences for all branches of astronomy. And already we see that even the teams using the Hubble Space Telescope will benefit from a verdict from Hipparcos on the distance scale that underpins all their reckonings of the expansion of the Universe." The pulse-rates of the stars Cepheid stars alternately squeeze themselves and relax, like a beating heart. They wax and wane rhythmically in brightness, every few days or weeks, at a rate that depends on their luminosity. Henrietta Leavitt at the Harvard College Observatory discovered in the early years of this century that bigger and more brilliant Cepheids vary with a longer period, according to a strict rule. It allows astronomers to gauge relative distances simply by taking the pulse-rates of the Cepheids and measuring their apparent brightnesses. Nearby Cepheids are typically 1000-2000 light-years away. They are too far for even Hipparcos to obtain very exact distance measurements, but by taking twenty-six examples and comparing them, Michael Feast and his colleague Robin Catchpole of RGO Cambridge arrive at consistent statistics. These define the relationship between the period and the luminosity, needed to judge the distances of Cepheids. The zero point is for an imaginary Cepheid pulsating once a day. This would be a star 300 times more luminous than the Sun, according to the Hipparcos data. The slowest Cepheid in the sample, l Carinae, has a period of 36 days and is equivalent to 18,000 suns

  8. Aerosol climate time series from ESA Aerosol_cci (Invited)

    NASA Astrophysics Data System (ADS)

    Holzer-Popp, T.

    2013-12-01

    Within the ESA Climate Change Initiative (CCI) the Aerosol_cci project (mid 2010 - mid 2013, phase 2 proposed 2014-2016) has conducted intensive work to improve algorithms for the retrieval of aerosol information from European sensors AATSR (3 algorithms), PARASOL, MERIS (3 algorithms), synergetic AATSR/SCIAMACHY, OMI and GOMOS. Whereas OMI and GOMOS were used to derive absorbing aerosol index and stratospheric extinction profiles, respectively, Aerosol Optical Depth (AOD) and Angstrom coefficient were retrieved from the other sensors. Global datasets for 2008 were produced and validated versus independent ground-based data and other satellite data sets (MODIS, MISR). An additional 17-year dataset is currently generated using ATSR-2/AATSR data. During the three years of the project, intensive collaborative efforts were made to improve the retrieval algorithms focusing on the most critical modules. The team agreed on the use of a common definition for the aerosol optical properties. Cloud masking was evaluated, but a rigorous analysis with a pre-scribed cloud mask did not lead to improvement for all algorithms. Better results were obtained using a post-processing step in which sudden transitions, indicative of possible occurrence of cloud contamination, were removed. Surface parameterization, which is most critical for the nadir only algorithms (MERIS and synergetic AATSR / SCIAMACHY) was studied to a limited extent. The retrieval results for AOD, Ångström exponent (AE) and uncertainties were evaluated by comparison with data from AERONET (and a limited amount of MAN) sun photometer and with satellite data available from MODIS and MISR. Both level2 and level3 (gridded daily) datasets were validated. Several validation metrics were used (standard statistical quantities such as bias, rmse, Pearson correlation, linear regression, as well as scoring approaches to quantitatively evaluate the spatial and temporal correlations against AERONET), and in some cases

  9. Suppression of thermal carrier escape and efficient photo-carrier generation by two-step photon absorption in InAs quantum dot intermediate-band solar cells using a dot-in-well structure

    NASA Astrophysics Data System (ADS)

    Asahi, S.; Teranishi, H.; Kasamatsu, N.; Kada, T.; Kaizu, T.; Kita, T.

    2014-08-01

    We investigated the effects of an increase in the barrier height on the enhancement of the efficiency of two-step photo-excitation in InAs quantum dot (QD) solar cells with a dot-in-well structure. Thermal carrier escape of electrons pumped in QD states was drastically reduced by sandwiching InAs/GaAs QDs with a high potential barrier of Al0.3Ga0.7As. The thermal activation energy increased with the introduction of the barrier. The high potential barrier caused suppression of thermal carrier escape and helped realize a high electron density in the QD states. We observed efficient two-step photon absorption as a result of the high occupancy of the QD states at room temperature.

  10. Demonstration That Calibration of the Instrument Response to Polarizations Parallel and Perpendicular to the Object Space Projected Slit of an Imaging Spectrometer Enable Measurement of the Atmospheric Absorption Spectrum in Region of the Weak CO2 Band for the Case of Arbitrary Polarization: Implication for the Geocarb Mission

    NASA Astrophysics Data System (ADS)

    Kumer, J. B.; Rairden, R. L.; Polonsky, I. N.; O'Brien, D. M.

    2014-12-01

    The Tropospheric Infrared Mapping Spectrometer (TIMS) unit rebuilt to operate in a narrow spectral region, approximately 1603 to 1615 nm, of the weak CO2 band as described by Kumer et al. (2013, Proc. SPIE 8867, doi:10.1117/12.2022668) was used to conduct the demonstration. An integrating sphere (IS), linear polarizers and quarter wave plate were used to confirm that the instrument's spectral response to unpolarized light, to 45° linearly polarized light and to circular polarized light are identical. In all these cases the intensity components Ip = Is where Ip is the component parallel to the object space projected slit and Is is perpendicular to the slit. In the circular polarized case Ip = Is in the time averaged sense. The polarizer and IS were used to characterize the ratio Rθ of the instrument response to linearly polarized light at the angle θ relative to parallel from the slit, for increments of θ from 0 to 90°, to that of the unpolarized case. Spectra of diffusely reflected sunlight passed through the polarizer in increments of θ, and divided by the respective Rθ showed identical results, within the noise limit, for solar spectrum multiplied by the atmospheric transmission and convolved by the Instrument Line Shape (ILS). These measurements demonstrate that unknown polarization in the diffusely reflected sunlight on this small spectral range affect only the slow change across the narrow band in spectral response relative to that of unpolarized light and NOT the finely structured / high contrast spectral structure of the CO2 atmospheric absorption that is used to retrieve the atmospheric content of CO2. The latter is one of the geoCARB mission objectives (Kumer et al, 2013). The situation is similar for the other three narrow geoCARB bands; O2 A band 757.9 to 768.6 nm; strong CO2 band 2045.0 to 2085.0 nm; CH4 and CO region 2300.6 to 2345.6 nm. Polonsky et al have repeated the mission simulation study doi:10.5194/amt-7-959-2014 assuming no use of a geo

  11. Near-infrared absorptions of monomethylhydrazine

    NASA Technical Reports Server (NTRS)

    Murray, Mark; Kurtz, Joe

    1993-01-01

    The peak absorption coefficients for two near-infrared absorptions of monomethylhydrazine, CH3-N2H3, (MMH) were measured. Absorption bands located at 1.524 micrometers (6560/cm), 1.557 micrometers (6423/cm), and 1.583 micrometers (6316/cm) are assigned to the Delta upsilon = 2 overtones of the infared N-H stretching fundamentals at 3317, 3245 and 3177/cm. An absorption band located at 1.04 micrometers (9620 +/- 100/cm) is assigned to the Delta upsilon = 3 overtone of one of these fundamentals. The peak absorption coefficients (alpha(sub 10)) at 1.524 micrometers (6560 +/- 20/cm) and 1.04 micrometers (9620 +/- 100/cm) are 31 x 10(exp -3) and 0.97 x 10(exp -3)/(cm atm), respectively. Uncertainties in these coefficients were estimated to be less than +/- 20% due primarily to uncertainties in the partial vapor pressure of MMH.

  12. NASA AND ESA Partnership on the Multi-Purpose Crew Vehicle Service Module

    NASA Technical Reports Server (NTRS)

    Free, James M.; Schubert, Kathleen; Grantier, Julie

    2012-01-01

    In March 2011, NASA and ESA made a decision to partially offset the European obligations deriving from the extension of the ISS Program until the end of 2020 with different means than ATVs, following the ATV-5 mission foreseen in mid-2014. NASA and ESA considered a number of barter options, and concluded that the provision by ESA of the Service Module and Spacecraft Adaptor for the NASA Multi-Purpose Crew Vehicle (MPCV) was the barter element with the most interest. A joint ESA - NASA working group was established to assess the feasibility of Europe developing this Module based on ATV heritage. The working group was supported by European and US industry namely Astrium, TAS-I and Lockheed-Martin. This paper gives an overview of the results of the on-going study as well as its projected utilization for the global space exploration endeavour.

  13. ANALYTICAL METHOD DEVELOPMENT FOR ALACHLOR ESA AND OTHER ACETANILIDE HERBICIDE DEGRADATION PRODUCTS

    EPA Science Inventory

    In 1998, USEPA published a Drinking Water Contaminant Candidate List (CCL) of 50 chemicals and 10 microorganisms. "Alachlor ESA and other acetanilide herbicide degradation products" is listed on the the 1998 CCL. Acetanilide degradation products are generally more water soluble...

  14. NASA and ESA Collaboration on Hexavalent Chrome Alternatives Pretreatments Only Interim Test Report

    NASA Technical Reports Server (NTRS)

    Kessel, Kurt R.

    2015-01-01

    NASA and ESA continue to search for an alternative to hexavalent chromium in coatings applications that meet their performance requirements in corrosion protection, cost, operability, and health and safety, while typically specifying that performance must be equal to or greater than existing systems. The overall objective of the collaborative effort between NASA TEERM and ESA is to test and evaluate coating systems (pretreatments, pretreatments with primer, and pretreatments with primer and topcoat) as replacements for hexavalent chrome coatings in aerospace applications. This objective will be accomplished by testing promising coatings identified from previous NASA, ESA, Department of Defense (DOD), and other project experience. Additionally, several new materials will be analyzed according to ESA-identified specifications.

  15. Band Structures of Plasmonic Polarons

    NASA Astrophysics Data System (ADS)

    Caruso, Fabio; Lambert, Henry; Giustino, Feliciano

    2015-03-01

    In angle-resolved photoemission spectroscopy (ARPES), the acceleration of a photo-electron upon photon absorption may trigger shake-up excitations in the sample, leading to the emission of phonons, electron-hole pairs, and plasmons, the latter being collective charge-density fluctuations. Using state-of-the-art many-body calculations based on the `GW plus cumulant' approach, we show that electron-plasmon interactions induce plasmonic polaron bands in group IV transition metal dichalcogenide monolayers (MoS2, MoSe2, WS2, WSe2). We find that the energy vs. momentum dispersion relations of these plasmonic structures closely follow the standard valence bands, although they appear broadened and blueshifted by the plasmon energy. Based on our results we identify general criteria for observing plasmonic polaron bands in the angle-resolved photoelectron spectra of solids.

  16. A simplified method to detect epididymal sperm aneuploidy (ESA) in mice using three-chromosome fish

    SciTech Connect

    Lowe, X.; O`Hogan, S.; Wyrobek, A.

    1995-11-01

    We developed a new method (ESA) to detect aneuploidy and polyploidy in epididymal sperm of mice using three-chromosome FISH. In comparison to a previous method (TSA-testicular spermatid aneuploidy), which required late-step spermatids, the ESA method utilizes epididymal sperm, which are easier to collect than testicular cells. The ESA method also provides a homogenous population of cells, which significantly speeds up the scoring procedure. A total of 6 mice were investigated by the ESA method and results compared with those obtained by the TSA method: 2 mice each of Robertsonian (8.14) heterozygotes, Rb(8.14) homozygotes and B6C3F1. About 10,000 sperm were scored per mouse. For the ESA method, epididimides were cut into small pieces and filtered. Sperm were prepared for hybridization by sonication and a modification of the DTT/LIS method previously described. Sperm aneuploidy was detected by multi-color FISH using three DNA probes specific for mouse chromosomes X, Y and 8. The sex ratio of X8(49.7%) and Y8(49.6%) did not differ from the expected 1:1. The efficiency of ESA was very high; -0.3% of the cells showed no hybridization domain. Hyperhaploidy frequencies for chromosomes X, Y and 8 compared well between the ESA and TSA methods for Rb(8.14) heterozygous (p=0.79) and B6C3F1 mice (p>0.05). The data obtained from Rb(8.14) homozygotes were similar to those from B6C3F1, as predicted (p=0.3). This highly efficient ESA assay is therefore, recommended for future studies of the mechanism of induction of aneuploidy in male germ cells. It also lays a solid foundation for automated scoring.

  17. The Oxygen a Band

    NASA Astrophysics Data System (ADS)

    Benner, D. Chris; Devi, V. Malathy; Hoo, Jiajun; Hodges, Joseph; Long, David A.; Sung, Keeyoon; Drouin, Brian; Okumura, Mitchio; Bui, Thinh Quoc; Rupasinghe, Priyanka

    2014-06-01

    The oxygen A band is used for numerous atmospheric experiments, but spectral line parameters that sufficiently describe the spectrum to the level required by OCO2 and other high precision/accuracy experiments are lacking. Fourier transform spectra from the Jet Propulsion Laboratory and cavity ring down spectra from the National Institute of Standards and Technology were fitted simultaneously using the William and Mary multispectrum nonlinear least squares fitting technique into a single solution including the entire band. In addition, photoacoustic spectra already available from the California Institute of Technology will be added to the solution. The three types of spectrometers are complementary allowing the strengths of each to fill in the weaknesses of the others. With this technique line positions, intensities, widths, shifts, line mixing, Dicke narrowing, temperature dependences and collision induced absorption have been obtained in a single physically consistent fit. D. Chris Benner, C. P. Rinsland, V. M. Devi, M. A. H. Smith, and D. Atkins, JQSRT 1995;53:705-21. Part of the research described in this paper was performed at The College of William and Mary, the, Jet Propulsion Laboratory, California Institute of Technology, under contracts and cooperative agreements with the National Aeronautics and Space Administration and the Jet Propulsion Laboratory. Support for the National Institute of Standards and Technology was provided by the NIST Greenhouse Gas Measurements and Climate Research Program and a NIST Innovations in Measurement Science (IMS) award.

  18. Study of Evanescence Wave Absorption in Lindane

    NASA Astrophysics Data System (ADS)

    Marzuki, A.; Prasetyo, E.; Gitrin, M. P.; Suryanti, V.

    2017-02-01

    Evanescent wave field has been studied for the purpose of tailoring fiber sensor capable of detecting lindane concentration in a solution. The mounted fiber was optically polished such that part of the fiber clad is stripped off. To study the evanescent wave field absorption in lindane solution, the unclad fiber was immersed in the solution. Light coming out of the fiber was studied at different wavelength each for different lindane concentration. It was shown that evanescent wave field absorption is stronger at wavelength corresponding to lindane absorption band as has been shown from absorption studies lindane in UV-VIS-NIR spectrophotometer.

  19. NASA and ESA Partnership on the Multi-Purpose Crew Vehicle Service Module

    NASA Technical Reports Server (NTRS)

    Schubert, Kathleen E.; Grantier, Julie A.

    2012-01-01

    (1) ESA decided in its Council Meeting in March 2011 to partially offset the European ISS obligations after 2015 with different means than ATVs; (2) The envisioned approach is based on a barter element(s) that would generate cost avoidance on the NASA side; (3) NASA and ESA considered a number of Barter options, NASA concluded that the provision by ESA of the Service Module for the NASA Multi-Purpose Crew Vehicle (MPCV) was the barter with the most interest;. (4) A joint ESA - NASA working group was established in May 2011 to assess the feasibility of Europe developing this Module based on ATV heritage; (5)The working group was supported by European and US industry namely Astrium, TAS-I and Lockheed-Martin; and (6) The project is currently in phase B1 with the objective to prepare a technical and programmatic proposal for an ESA MPCV-SM development. This proposal will be one element of the package that ESA plans submit to go forward for approval by European Ministers in November 2012.

  20. Overview on calibration and validation activities and first results for ESA's Soil Moisture and Ocean Salinity Mission

    NASA Astrophysics Data System (ADS)

    Mecklenburg, Susanne; Bouzinac, Catherine; Delwart, Steven; Lopez-Baeza, Ernesto

    exercise to verify that the methodology proposed actually meets the foreseen performances. Other activities include the deployment of the ground-based ESA funded ELBARA radiometers. Also, in collaboration with the Technical University Vienna, ESA funds the establishment of a soil moisture network data hosting facility in support to the SMOS calibration and validation activities. The validation of sea surface salinity data products will be a challenging task requiring a highly accurate and stable instrument calibration. At local scales, the foreseen validation activities are focused on a better understanding of the emission of L-band radiation from the sea surface through dedicated airborne campaigns, whereas validation at global scales will rely on buoy networks and basin scale ocean models. Close collaboration with the NASA Aquarius Team will further contribute to the validation of sea surface salinity data products. A variety of campaigns, such as DOMEX, CoSMOS, WISE, LOSAC, EUROSTARRS, FROG, SMOSREX have been (and will be) performed to investigate uncertainties in the soil moisture and ocean salinity retrieval. The major aspects to investigate with regard to soil moisture are the influence of the various types of vegetation and their seasonal variability, as well as the influence of surface roughness. Over oceans, the impact of sea-surface state on the polarimetric radiometric signal is the main issue. The DOMEX campaigns will provide information for vicarious calibration over Antarctica. The presentation will provide an overview on the calibration and validation activities carried out in the SMOS commissioning phase as well as first results.

  1. [Decomposition of hemoglobin UV absorption spectrum into absorption spectra of prosthetic group and apoprotein by means of an additive model].

    PubMed

    Lavrinenko, I A; Vashanov, G A; Artyukhov, V G

    2015-01-01

    The decomposition pathways of hemoglobin UV absorption spectrum into the absorption spectra of the protein and non-protein components are proposed and substantiated by means of an additive model. We have established that the heme component has an absorption band with a maximum at λ(max) = 269.2 nm (ε = 97163) and the apoprotein component has an absorption band with a maximum at λ(max) = 278.4 nm (ε = 48669) for the wavelength range from 240.0 to 320.0 nm. An integral relative proportion of absorption for the heme fraction (78.8%) and apoprotein (21.2%) in the investigating wavelength range is defined.

  2. Foton 11: ESA investigates further the space environment and its impact on organisms

    NASA Astrophysics Data System (ADS)

    1997-10-01

    Scientific research conducted under space conditions can provide new insight into how processes occur on Earth and organisms function. The unmanned Foton spacecraft has been used since 1988 to conduct such investigations. Now on its 11th mission and the fifth in which ESA has taken part, Foton is carrying some 80 kg of ESA payload: two ESA research facilities (an incubator and an experiment holder on the outside of the spacecraft) are on board along with 12 scientific experiments. The French space agency (CNES) and the German space agency (DARA) also have payload on the spacecraft. ESA's space-qualified incubator, called Biobox, keeps organisms at predefined conditions. During this mission, the three Biobox experiments are looking at the reaction of bone cells in microgravity. The second ESA facility, a pan-shaped container called Biopan attached to the outside of Foton, is used to expose experiment samples directly to the space environment in order to study the impact of space's extreme temperatures, ultraviolet and cosmic radiation, and near-perfect vacuum. On this mission, the six Biopan experiments are concentrating on exobiology, radiation biology and material science. Biopan has a motor-driven, hinged lid and is equipped with devices and sensors that measure the various aspects of the environment to which the experiments are subjected. Once Foton is in orbit, a telecommand is sent from ground and the lid opens to expose the samples to the environment. At the end of the mission, another command is sent and the lid closes. Since Biopan is on the outside of Foton, it also has its own ablative heat shield to protect the facility and samples during the spacecraft's re-entry and landing. Other ESA experiments on board Foton are looking into the effects of weightlessness on bacteria, the biological clocks of beetles and the aging of fruitflies. The scientific investigators responsible for the ESA experiments are from research institutes and universities in Belgium

  3. ESA is hot on the trail of Geminga

    NASA Astrophysics Data System (ADS)

    XMM-Newton image of Geminga showing the discovery of the twi hi-res Size hi-res: 68 kb Credits: ESA XMM-Newton image of Geminga showing the discovery of the twin tails This image was captured by the EPIC camera on board the satellite. The motion of Geminga across the sky is indicated, showing that the tails are trailing the neutron star. The scale bar corresponds to a distance of 1.5 million million kilometres at the distance of Geminga. Computer models of the shock wave created by Geminga hi-res Size hi-res: 522 kb Credits: Patrizia Caraveo Computer models of the shockwave created by Geminga Computer models of the shockwave created by Geminga show that the best matches to the data occur if the neutron star is travelling virtually across our line of sight. These correspond to the inclinations of less than 30 degrees. A neutron star measures only 20-30 kilometres across and is the dense remnant of an exploded star. Geminga is one of the closest to Earth, at a distance of about 500 light-years. Most neutron stars emit radio emissions, appearing to pulsate like a lighthouse, but Geminga is 'radio-quiet'. It does, however, emit huge quantities of pulsating gamma rays making it one of the brightest gamma-ray sources in the sky. Geminga is the only example of a successfully identified gamma-ray source from which astronomers have gained significant knowledge. It is 350 000 years old and ploughs through space at 120 kilometres per second. Its route creates a shockwave that compresses the gas of the interstellar medium and its naturally embedded magnetic field by a factor of four. Patrizia Caraveo, Instituto di Astrofisica Spaziale e Fisica Cosmica, Milano, Italy, and her colleagues (at CESR, France, ESO and MPE, Germany) have calculated that the tails are produced because highly energetic electrons become trapped in this enhanced magnetic field. As the electrons spiral inside the magnetic field, they emit the X-rays seen by XMM-Newton. The electrons themselves are created

  4. Multi-band slow light metamaterial.

    PubMed

    Zhu, Lei; Meng, Fan-Yi; Fu, Jia-Hui; Wu, Qun; Hua, Jun

    2012-02-13

    In this paper, a multi-band slow light metamaterial is presented and investigated. The metamaterial unit cell is composed of three cut wires of different sizes and parallel to each other. Two transparency windows induced by two-two overlaps of absorption bands of three cut wires are observed. The multi-band transmission characteristics and the slow light properties of metamaterial are verified by numerical simulation, which is in a good agreement with theoretical predictions. The impacts of structure parameters on transparency windows are also investigated. Simulation results show the spectral properties can be tuned by adjusting structure parameters of metamaterial. The equivalent circuit model and the synthesis method of the multi-band slow light metamaterial are presented. It is seen from simulation results that the synthesis method accurately predicts the center frequency of the multi-band metamaterial, which opens a door to a quick and accurate construction for multi-band slow light metamaterial.

  5. Physical Properties of White Dwarfs from Multi-Band Photometry

    NASA Astrophysics Data System (ADS)

    Raddi, R.

    2017-03-01

    We describe a hierarchical Bayesian model to measure the physical parameters (mass, cooling age, distance, interstellar extinction) of single white dwarfs using only multi-band UV to IR photometry. We test our model on a set of known white dwarfs with well-assessed atmospheric parameters, determined via optical spectroscopy. Looking forward to the results of the ESA Gaia mission, we derive the posterior distributions of white dwarf parameters in two different scenarios with known or unknown parallaxes.

  6. ABSORPTION ANALYZER

    DOEpatents

    Brooksbank, W.A. Jr.; Leddicotte, G.W.; Strain, J.E.; Hendon, H.H. Jr.

    1961-11-14

    A means was developed for continuously computing and indicating the isotopic assay of a process solution and for automatically controlling the process output of isotope separation equipment to provide a continuous output of the desired isotopic ratio. A counter tube is surrounded with a sample to be analyzed so that the tube is exactly in the center of the sample. A source of fast neutrons is provided and is spaced from the sample. The neutrons from the source are thermalized by causing them to pass through a neutron moderator, and the neutrons are allowed to diffuse radially through the sample to actuate the counter. A reference counter in a known sample of pure solvent is also actuated by the thermal neutrons from the neutron source. The number of neutrons which actuate the detectors is a function of a concentration of the elements in solution and their neutron absorption cross sections. The pulses produced by the detectors responsive to each neu tron passing therethrough are amplified and counted. The respective times required to accumulate a selected number of counts are measured by associated timing devices. The concentration of a particular element in solution may be determined by utilizing the following relation: T2/Ti = BCR, where B is a constant proportional to the absorption cross sections, T2 is the time of count collection for the unknown solution, Ti is the time of count collection for the pure solvent, R is the isotopic ratlo, and C is the molar concentration of the element to be determined. Knowing the slope constant B for any element and when the chemical concentration is known, the isotopic concentration may be readily determined, and conversely when the isotopic ratio is known, the chemical concentrations may be determined. (AEC)

  7. Reflective-tube absorption meter

    NASA Astrophysics Data System (ADS)

    Zaneveld, J. Ronald V.; Bartz, Robert; Kitchen, James C.

    1990-09-01

    The design and calibration of a proposed in situ spectral absorption meter is evaluated using a laboratory prototype. The design includes a silver coated (second-surface) glass tube, a tungsten light source (stabilized by means of optical feedback), a monochromator, and a solid state detector. The device measures the absorption coefficient plus a portion of the volume scattering function. Theoretical analyses and laboratory experiments which explore the magnitude and variation of the errors due to scattering and internal reflections are described. Similar analyses are performed on the Cary 1 18 Spectrophotometer to allow cross calibration. Algorithms to yield the abscrption coefficient and the zenith-sun diffuse attenuation coefficient are presented and evaluated. Simultaneous measurement of the beam attenuation or backscattering coefficient allows use of algoriThms with much narrower error bands. The various methods of obtaining absorption and diffuse attenuation values are compared. Procedures for using reverse osmosis filtration to produce a clean water calibration standard are described. An absorption spectrum for pure water is obtained. Development of the absorption meter is proceeding along two lines: 1) a two-wavelength side-by-side LED is being fabricated to allow an in situ chlorophyll a absorption meter to be constructed, and 2) scientific projects using a shipboard or laboratory flow.-through pumping system are being planned.

  8. Excited-state absorption measurements of Tm3+-doped crystals

    NASA Astrophysics Data System (ADS)

    Szela, J. W.; Mackenzie, J. I.

    2012-06-01

    High resolution, absolute excited-state absorption (ESA) spectra, at room temperature, from the long-lived 3F4 energy level of several crystals doped with trivalent thulium (Tm3+) ions have been measured employing high-brightness narrowband (FWHM <30 nm) light emitting diodes (LEDs) as a probe wavelength. The aim of this investigation was to determine the strength of ESA channels at wavelengths addressable by commercially available semiconductor laser diodes operating around 630-680 nm. The favourable lifetime of the 3F4 manifold and negligible ground-state absorption (GSA) for the red-wavelength second-step excitation, ensures a direct and efficient route for a dual-wavelength pumping scheme of the thulium ion, which will enable blue-green laser emission from its 1G4 upper-laser level.

  9. Come to Noyon (France) and follow the solar eclipse with ESA

    NASA Astrophysics Data System (ADS)

    1999-08-01

    ESA will feature a special exhibition stand where the public, amateurs and press can obtain information. During the partial eclipse phases, the latest images from ESA's solar observatory SOHO and from other European eclipse sites, coming via the Internet or traditional broadcast, will be shown on a large video screen. The magic of the total eclipse in Noyon will last 2 minutes and 11 seconds. ESA has set up a multi-site eclipse imaging campaign over Europe to capture a long eclipse sequence from the Atlantic, the UK, France (Noyon and Strasbourg), Germany, Austria/ Hungary (at an international camp of young astronomers) and Romania. High-definition still and video images of the eclipse will be available live on the Internet. Check our site http://sci.esa.int/eclipse99/ Noyon will also host a press briefing at the eclipse site Media Centre at 9h30-10h30, and again at 13h15-14h15, after the eclipse shadow has left Europe. Opportunities for interviews with ESA multi-language staff and other specialists will be possible after the eclipse. Over the week leading up to the eclipse, ESA representatives are also participating in press and public conferences. Daily press conferences are scheduled in Strasbourg at the France 3 Auditorium from 4 to 11 August at 16:00-18:00 hrs, in Paris at the Museum d'Histoire Naturelle from 5 -12 August (except 11 August) at 10:00-12:00 hrs, and in Stuttgart at the Science Fair, where an ESA/Max Plank Institute stand has also been set up.

  10. First observation of 628 CO 2 isotopologue band at 3.3 μm in the atmosphere of Venus by solar occultation from Venus Express

    NASA Astrophysics Data System (ADS)

    Bertaux, Jean-Loup; Vandaele, Ann Carine; Wilquet, Valérie; Montmessin, F.; Dahoo, R.; Villard, E.; Korablev, O.; Fedorova, A.

    2008-05-01

    The new ESA Venus Express orbiter is the first mission applying the probing technique of solar and stellar occultation to the atmosphere of Venus, with the SPICAV/SOIR instrument. SOIR is a new type of spectrometer used for solar occultations in the range 2.2-4.3 μm. Thanks to a high spectral resolving power R˜15,000-20,000 (unprecedented in planetary space exploration), a new gaseous absorption band was soon detected in the atmospheric transmission spectra around 2982 cm -1, showing a structure resembling an unresolved Q branch and a number of isolated lines with a regular wave number pattern. This absorption could not be matched to any species contained in HITRAN or GEISA databases, but was found very similar to an absorption pattern observed by a US team in the spectrum of solar light reflected by the ground of Mars [Villanueva, G.L., Mumma, M.J., Novak, R.E., Hewagama, T., 2008. Icarus 195 (1), 34-44]. This team then suggested to us that the absorption was due to an uncatalogued transition of the 16O 12C 18O molecule. The possible existence of this band was soon confirmed from theoretical considerations by Perevalov and Tashkun. Some SOIR observations of the atmospheric transmission are presented around 2982 cm -1, and rough calculations of line strengths of the Q branch are produced, based on the isotopic ratio measured earlier in the lower atmosphere of Venus. This discovery emphasizes the role of isotopologues of CO 2 (as well as H 2O and HDO) as important greenhouse gases in the atmosphere of Venus.

  11. Cloud Information Content Analysis for EPIC's Oxygen A- and B-band Channels

    NASA Astrophysics Data System (ADS)

    Davis, A. B.; Sanghavi, S.

    2011-12-01

    The Earth Polychromatic Imaging Camera (EPIC) instrument on the Deep Space Climate Observatory (DSCOVR) will have two molecular oxygen channels: one for the well-known ``A'' band at~764 nm and one for the weaker ``B'' band at 688~nm. In both cases, a channel-integrated relative measurement of absorption is possible using an ``in-band'' channel and a nearby ``reference'' channel. Together, these four observations enable a rudimentary differential optical absorption spectroscopy (DOAS) of O2 in the characteristic retro-reflection geometry of the L1 vantage point. A priori, we thus have at best two new pieces of cloud information to access. EPIC's pixels have 10x10 km2 footprints at nadir (center of the illuminated disk), more as the viewing angle increases away from local zenith. What new information can be learned about clouds from these data on a pixel-by-pixel basis? O2 A-band observations from space have been pioneered with CNES's POLDER, ESA's SCIAMACHY, and JAXA's GOSat. NASA's OCO-2, to be launched in early 2013, will also have A-band capability. POLDER has low spectral and spatial resolutions, but offers multiple viewing directions for every pixel; SCIAMACHY has higher spectral but worse spatial resolution and just one viewing angle. GOSat has very high spectral but rather low spatial resolutions, again with the possibility of dense angular sampling, but no imaging (just one pixel at a time). OCO-2, a narrow swath imager, will have similarly high spectral resolution and reasonably high ( ˜2~km) spatial resolution. Of these four LEO missions, two are focused on CO2 DOAS, with O2 being assayed operationally only to deliver it in ppm's. POLDER and SCIAMACHY however have official cloud products based on A-band measurements. They contain, at the least, an estimate of cloud top height and, at the most, that plus an estimate of cloud pressure thickness. Cloud optical depth and effective particle size are derived from other spectral data, including continuum values

  12. Computer programs for absorption spectrophotometry.

    PubMed

    Jones, R N

    1969-03-01

    Brief descriptions are given of twenty-two modular computer programs for performing the basic numerical computations of absorption spectrophotometry. The programs, written in Fortran IV for card input and output, are available from the National Research Council of Canada. The input and output formats are standardized to permit easy interfacing to yield more complex data processing systems. Though these programs were developed for ir spectrophotometry, they are readily modified for use with digitized visual and uv spectrophotometers. The operations covered include ordinate and abscissal unit and scale interconversions, ordinate addition and subtraction, location of band maxima and minima, smoothing and differentiation, slit function convolution and deconvolution, band profile analysis and asymmetry quantification, Fourier transformation to time correlation curves, multiple overlapping band separation in terms of Cauchy (Lorentz), Gauss, Cauchy-Gauss product, and Cauchy-Gauss sum functions and cell path length determination from fringe spacing analysis.

  13. Metamaterial with electromagnetic transparency under multiband absorptions

    NASA Astrophysics Data System (ADS)

    Zhang, Xu; Qi, Limei

    2017-02-01

    We propose a metal-dielectric-metal (MDM) metamaterial that has an electromagnetic (EM) transparency spectrum under multiband absorptions in the C and the X bands. The ground continuous metal film used in the conventional metamaterial absorber (MA) is replaced by a structured ground plane (SGP) in our design. The band-pass properties of the front patterned metal film and the SGP determine the EM transparency spectrum, while the magnetic and the electric resonances in the MDM structure contribute to the multiband absorptions. Due to the symmetric structure of the unit cell, the absorption bands and the EM transparency spectrum of the metamaterial have the property of polarization independency. Despite the normal incidence, the metamaterial can also be used for non-normal incidence.

  14. The European space exploration programme: current status of ESA's plans for Moon and Mars exploration.

    PubMed

    Messina, Piero; Vennemann, Dietrich

    2005-01-01

    After a large consultation with the scientific and industrial communities in Europe, the Aurora Space Exploration Programme was unanimously approved at the European Space Agency (ESA) Council at ministerial level in Edinburgh in 2001. This marked the start of the programme's preparation phase that was due to finish by the end of 2004. Aurora features technology development robotic and crewed rehearsal missions aimed at preparing a human mission to Mars by 2033. Due to the evolving context, both international and European, ESA has undertaken a review of the goals and approach of its exploration programme. While maintaining the main robotic missions that had been conceived during Aurora, the European Space Exploration Programme that is currently being proposed to the Aurora participating states and other ESA Member States has a reviewed approach and will feature a greater synergy with other ESA programmes. The paper will present the process that led to the revision of ESA's plans in the field of exploration and will give the current status of the programme.

  15. Transitioning research to application in the area of space weather at ESA

    NASA Astrophysics Data System (ADS)

    Hilgers, Alain; Glover, Alexi; Daly, Eamonn; Luntama, Juha-Pekka

    This presentation gives an overview of the past and current ESA space weather research ac-tivities and discusses the approaches used or foreseen for transitioning research products into application. Since its establishment ESA has supported and coordinated space weather re-search through its various programmes. The scientific programme has especially contributed to the investigation of key scientific aspects of space weather phenomena while the technology and research programmes targeted the effects of space environments on space systems. In 1998 ESA has started consultations among member states and performed studies to identify the requirements for a future European wide space weather application programme encompassing monitoring and forecasting services to support and protect the operation of space and ground based systems. As a by-product, structural developments were made including the establish-ment of a network of space weather service prototypes (SWENET). In 2008 the council of ESA decided to initiate a Space Situational Awareness (SSA) programme including space weather as one of the pillars together with space surveillance and near-Earth objects elements. Since the Space Weather element is planned to primarily rely on relevant existing assets it will provide a framework for transitioning several research assets of ESA and its member states to operational components of the overall system. Other paths will be considered for other assets which are not directly relevant to the SSA programme or which are still in a early research stage.

  16. High-Absorption-Efficiency Superlattice Solar Cells by Excitons

    NASA Astrophysics Data System (ADS)

    Nishinaga, Jiro; Kawaharazuka, Atsushi; Onomitsu, Koji; Horikoshi, Yoshiji

    2013-11-01

    The effect of excitonic absorption on solar cell efficiency has been investigated using solar cells with AlGaAs/GaAs superlattice structures. Numerical calculations reveal that excitonic absorption considerably enhances the overall absorption of bulk GaAs. Excitonic absorption shows strong and sharp peaks at the absorption edge and in the energy region above the band gap. Absorption enhancement is also achieved in the AlGaAs/GaAs superlattice. The measured quantum efficiency spectra of the superlattice solar cells are quite similar to the calculated absorption spectra considering the excitonic effect. The superlattice solar cells are confirmed to have high absorption coefficient compared with the GaAs and AlGaAs bulk solar cells. These results suggest that the enhanced absorption by excitons can increase the quantum efficiency of solar cells. This effect is more prominent for the solar cells with small absorption layer thicknesses.

  17. Interpretation of the Minkowski bands in Grw + 70 deg 8247.

    NASA Technical Reports Server (NTRS)

    Angel, J. R. P.

    1972-01-01

    Demonstration on the basis of the spectral structure of circular polarization in Grw + 70 deg 8247, that the absorption bands are at least in part molecular in origin. The spectrum of molecular helium has strong bands coincident with several of the Minkowski bands and, in particular, at high temperature shows a strong band head at about 4125 A. Helium molecules could be formed in sufficient density to give the absorption features in the star if it has a pure helium atmosphere. The Zeeman effect in molecular helium can explain in general the observed spectral features in the polarization and also may be responsible for the continuum polarization.

  18. Atmospheric Absorption Parameters for Laser Propagation

    DTIC Science & Technology

    2007-11-02

    high-resolution, good photometric accuracy data for numerous bands in the 3-5 Am region, using the facility at Kitt Peak National Solar Observatory. The...L49-L52 (2001). 44. A. Castrillo, G. Gagliardi, G. Casa , and L. Gianfrani, "Combined interferometric and absorption-spectroscopic technique for...from FT visible solar absorption spectra and evaluation of spectroscopic databases," JQRST 82, 133-150 (2003). 53. D. Jacquemart, R.R. Gamache, and L.S

  19. Cost considerations in database selection - A comparison of DIALOG and ESA/IRS

    NASA Technical Reports Server (NTRS)

    Jack, R. F.

    1984-01-01

    It is pointed out that there are many factors which affect the decision-making process in determining which databases should be selected for conducting the online search on a given topic. In many cases, however, the major consideration will be related to cost. The present investigation is concerned with a comparison of the costs involved in making use of DIALOG and the European Space Agency's Information Retrieval Service (ESA/IRS). The two services are very comparable in many respects. Attention is given to pricing structure, telecommunications, the number of databases, prints, time requirements, a table listing online costs for DIALOG and ESA/IRS, and differences in mounting databases. It is found that ESA/IRS is competitively priced when compared to DIALOG, and, despite occasionally higher telecommunications costs, may be even more economical to use in some cases.

  20. Large format array controller (aLFA-C): tests and characterisation at ESA

    NASA Astrophysics Data System (ADS)

    Lemmel, Frédéric; ter Haar, Jörg; van der Biezen, John; Duvet, Ludovic; Nelms, Nick; Blommaert, Sander; Butler, Bart; van der Luijt, Cornelis; Heijnen, Jerko; Smit, Hans; Visser, Ivo

    2016-08-01

    For future near infrared astronomy missions, ESA is developing a complete detection and conversion chain (photon to SpaceWire chain system): Large Format Array (aLFA-N) based on MCT type detectors. aLFA-C (Astronomy Large Format Array Controller): a versatile cryogenic detector controller. An aLFA-C prototype was developed by Caeleste (Belgium) under ESA contract (400106260400). To validate independently the performances of the aLFA-C prototype and consolidate the definition of the follow-on activity, a dedicated test bench has been designed and developed in ESTEC/ESA within the Payload Technology Validation group. This paper presents the test setup and the performance validation of the first prototype of this controller at room and cryogenic temperature. Test setup and software needed to test the HAWAII-2RG and aLFA-N detectors with the aLFA-C prototype at cryogenic temperature will be also presented.

  1. A new ESA educational initiative: Euro Space Center class teachers in microgravity during parabolic flights

    NASA Astrophysics Data System (ADS)

    Pletser, Vladimir; Paulis, Pierre Emmanuel; Loosveldt, Edwin; Gering, Dominique; Body, Mireille; Schewijck, Robert

    2005-12-01

    Since 1984, the European Space Agency (ESA) has organized 30 aircraft parabolic flight campaigns in the frame of its Microgravity Programme to perform short duration scientific and technological experiments. On each campaign, ESA invites journalists to report to the general public on the research work conducted in weightlessness. A new initiative was launched in 2000 with the introduction of pedagogical experiments aiming at educating youngsters and the general public on weightlessness effects. In November 2000, four secondary school teachers detached to the Euro Space Center (ESC) participated in the 29th ESA campaign. The ESC in Belgium provides recreational and educational activities for the general public and organizes space classes targeted at primary and secondary school pupils. The four teachers performed simple experiments with gyroscopes, yo-yos, magnetic balls, pendulum and food to explain their different behaviour in weightlessness, to show characteristics and possibilities of the microgravity environment and the difficulties that astronauts encounter in their daily life in orbit.

  2. ESA Press Event: See Mars Express before its departure to the Red Planet

    NASA Astrophysics Data System (ADS)

    2002-09-01

    Media representatives are invited to INTESPACE on Wednesday 18 September to learn about the mission and attend a ceremony at which a container filled with Ferrari's distinctive 'Rosso Corsa' red paint will be integrated with the spacecraft. Mr Antonio Rodotà (ESA Director General), Professor David Southwood (ESA Director of Science), senior representatives of the space industry and a representative from Ferrari will be giving presentations. Together with the ESA Mars Express project manager and project scientist, they will be available for interviews. Representatives of the media wishing to attend this media day at INTESPACE on Wednesday 18 September are kindly requested to complete the accreditation form and fax it to: Franco Bonacina, Head of Media Relations ESA/HQ, Paris, France Tel. +33 (0) 1 53697155 Fax. +33 (0) 1 53697690 Notes for Editors: 1. On 18 September at INTESPACE, Toulouse, ESA will integrate a sample of Ferrari's 'Rosso Corsa' red paint with the Mars Express spacecraft. This event is part of a new ESA communication policy aimed mainly at the general public. Ferrari have much to celebrate: the outstanding success of the Scuderia Ferrari, winning their fourth consecutive Formula One constructors' championship and Michael Schumacher his fifth Formula One drivers' championship. Responding to an ESA proposal, Ferrari have agreed to send the symbol of their winning formula on the ESA mission to the Red Planet. When Mars Express blasts into orbit next summer at 10 800 kilometres per hour, it will be the fastest that Ferrari's distinctive red paint has ever travelled. Following successful completion of a series of rigorous tests, the Ferrari red paint sample will be officially certified 'space qualified' at a ceremony at INTESPACE. Housed in a specially constructed glass globe known as FRED, it will then be formally integrated with the Mars Express craft. 2. The main objective of the Mars Express mission is to detect the presence of water below the

  3. The europa initiative for esa's cosmic vision: a potential european contribution to nasa's Europa mission

    NASA Astrophysics Data System (ADS)

    Blanc, Michel; Jones, Geraint H.; Prieto-Ballesteros, Olga; Sterken, Veerle J.

    2016-04-01

    The assessment of the habitability of Jupiter's icy moons is considered of high priority in the roadmaps of the main space agencies, including the decadal survey and esa's cosmic vision plan. the voyager and galileo missions indicated that europa and ganymede may meet the requirements of habitability, including deep liquid aqueous reservoirs in their interiors. indeed, they constitute different end-terms of ocean worlds, which deserve further characterization in the next decade. esa and nasa are now both planning to explore these ice moons through exciting and ambitious missions. esa selected in 2012 the juice mission mainly focused on ganymede and the jupiter system, while nasa is currently studying and implementing the europa mission. in 2015, nasa invited esa to provide a junior spacecraft to be carried on board its europa mission, opening a collaboration scheme similar to the very successful cassini-huygens approach. in order to define the best contribution that can be made to nasa's europa mission, a europa initiative has emerged in europe. its objective is to elaborate a community-based strategy for the proposition of the best possible esa contribution(s) to nasa's europa mission, as a candidate for the upcoming selection of esa's 5th medium-class mission . the science returns of the different potential contributions are analysed by six international working groups covering complementary science themes: a) magnetospheric interactions; b) exosphere, including neutrals, dust and plumes; c) geochemistry; d) geology, including expressions of exchanges between layers; e) geophysics, including characterization of liquid water distribution; f) astrobiology. each group is considering different spacecraft options in the contexts of their main scientific merits and limitations, their technical feasibility, and of their interest for the development of esa-nasa collaborations. there are five options under consideration: (1) an augmented payload to the europa mission main

  4. Upgrade of DRAMA-ESA's Space Debris Mitigation Analysis Tool Suite

    NASA Astrophysics Data System (ADS)

    Gelhaus, Johannes; Sanchez-Ortiz, Noelia; Braun, Vitali; Kebschull, Christopher; de Oliveira, Joaquim Correia; Dominguez-Gonzalez, Raul; Wiedemann, Carsten; Krag, Holger; Vorsmann, Peter

    2013-08-01

    One decade ago ESA started the dev elopment of the first version of the software tool called DRAMA (Debris Risk Assessment and Mitigation Analysis) to enable ESA space programs to assess their compliance with the recommendations in the European Code of Conduct for Space Debris Mitigation. This tool was maintained, upgraded and extended during the last year and is now a combination of five individual tools, each addressing a different aspect of debris mitigation. This paper gives an overview of the new DRAMA software in general. Both, the main tools ARES, OSCAR, MIDAS, CROC and SARA will be discussed and the environment used by DRAMA will be explained shortly.

  5. The Colour and Stereo Surface Imaging System for ESA's Trace Gas Orbiter

    NASA Astrophysics Data System (ADS)

    Thomas, Nicolas; Cremonese, Gabriele

    2016-04-01

    The Colour and Stereo Surface Imaging System (CaSSIS) is an 11 μrad/px imaging system ready to launch on the European Space Agency's (ESA) ExoMars Trace Gas Orbiter (TGO) on 14 March 2016 from Baikonur. CaSSIS is based around an 880 mm focal length carbon-fibre reinforced polymer (CFRP) telescope with a 135 mm primary mirror and a 2k x 2k CMOS hybrid detector with 10 micron pixel pitch providing 4.6 m/px imaging from the nominal 400 km circular orbit. The telescope is a slightly modified three mirror anastigmat optical configuration with no central obscuration. The instrument is designed to operate in "push-frame" mode where 2048 x 256 images are acquired at a repetition rate which matches the ground-track velocity (~3 km/s) allowing sufficient overlap for co-registration thereby building image strips along the surface. A filter strip assembly (FSA) is mounted directly above the detector providing images in 4 wavelength bands. Two of these (480.5nm and 676.5nm prior to convolution with the rest of the instrument) correspond closely to bands used by the HiRISE instrument on the Mars Reconnaissance Orbiter [4]. Two other filters split the NIR wavelengths with centres at 838 nm and close to 985 nm. Analyses show that the filters provide good differentiation between expected surface minerals, particularly Fe-bearing phases (Tornabene et al. LPSC, 2016). CaSSIS is designed to produce stereo from images acquired ~30 s apart by using a rotation drive. The telescope points 10 degrees off-nadir. The drive aligns the telescope with the ground-track direction so that the telescope is pointing forward. After image acquisition, the telescope is rapidly rotated by 180 degrees to point in the opposite direction and the second image of the stereo pair is acquired. CaSSIS will extend the monitoring of past missions to future years allowing the tracking of longer-term changes. It will also provide contemporaneous imaging of regions that may produce unique signatures detected by

  6. The design of Janus, the visible camera for the ESA JUICE mission

    NASA Astrophysics Data System (ADS)

    Della Corte, Vincenzo; Schmitz, Nicole; Castro, José Maria; Leese, Mark; Debei, Stefano; Magrin, Demetrio; Michalik, Harald

    2014-05-01

    The JUICE (JUpiter ICy moons Explorer) mission was selected in May 2012 as the first Large mission in the frame of the ESA Cosmic Vision 2015-2025 program. The mission is aimed at an in-depth characterization of the Jovian system, with an operational phase of about 3.5 years. During the whole operational phase, JANUS (Jovis, Amorum ac Natorum Undique Scrutator) will acquire panchromatic and narrow-band images in the visible - NIR range of many targets within