Search results for "Spectral"
showing 10 items of 3116 documents
Effect of water on glass transition in starch/sucrose matrices investigated through positron annihilation lifetime spectroscopy: a new approach
2011
Glass transition is studied through positron annihilation lifetime spectroscopy (PALS) in maize starch matrices containing 10 (batch STS10) and 20 (STS20) w/w% sucrose, as a function of temperature (T) and water content (c(w)). To circumvent important losses of water upon heating while recording the PALS spectra, a new method is developed: instead of a series of measurements of τ(3), the triplet positronium lifetime, at different T, the latter is kept constant and the series relates to c(w), which is left to decrease at a constant rate. Similarly to the changes in τ(3) with T, the τ(3)vs. c(w) plots obtained show a smooth linear increase until a break, denoting the occurrence of glass trans…
Diode laser spectroscopy of the nu(8) band of the SF(5)Cl molecule.
2003
Abstract Diode laser spectra of SF 5 Cl have been recorded in the ν 8 band region at a temperature of ca. 240 K, a pressure of 0.25 mbar and an instrumental bandwidth of ca. 0.001 cm −1 . Four regions have been studied: a first one in the P -branch (906.849–907.687 cm −1 ), a second one in the Q -branch (910.407–910.944 cm −1 ), and two other ones in the R -branch (913.957–914.556 and 917.853–918.705 cm −1 ). The whole ν 1 / ν 8 dyad of SF 5 35 Cl has been previously recorded in the group of Professor H. Burger in Wuppertal, thanks to a Fourier transform infrared spectrometer [J. Mol. Spectrosc. 208 (2001) 169]. These data have thus been combined with our diode laser ones in the aim of refi…
ANALYSIS OF SUNSPOT NUMBER FLUCTUATIONS
2004
Monthly averages of the sunspot number visible on the sun, observed from 1749, Zurich Observatory, and from 1848 other observatories, have been analyzed. This time signal presents a frequency power spectra with a clear 1/fα behavior with α≃0.8±0.2. The well-known cycle of approximately 11 years, clearly present in the spectrum, does not produce a sensible distortion of that behavior. The eventual characterization of the sunspot time series as a fractal is analyzed by means of the detrended fluctuation analysis (DFA). The jump-size distribution of the signal is also studied.
Near-Edge X-ray Absorption Fine Structure Investigation of the Quasi-One-Dimensional Organic Conductor (TMTSF)2PF6
2016
We present high-resolution near-edge X-ray absorption fine structure (NEXAFS) measurements at the P L2/3-edges, F K-edge, C K-edge and Se M2/3-edges of the quasi-one-dimensional (1D) conductor and superconductor (TMTSF)2PF6. NEXAFS allows probing the donor and acceptor moieties separately; spectra were recorded between room temperature (RT) and 30 K at normal incidence. Spectra taken around RT were also studied as a function of the angle (θ) between the electric field of the X-ray beam and the 1D conducting direction. In contrast with a previous study of the S L2/3-edges spectra in (TMTTF)2AsF6, the Se M2/3-edges of (TMTSF)2PF6 do not exhibit a well resolved spectrum. Surprisingly, the C K-…
Spectroscopy ofLiΛ9by electroproduction
2015
Background: In the absence of accurate data on the free two-body hyperon-nucleon interaction, the spectra of hypernuclei provides information on the details of the effective hyperon-nucleon interaction.Purpose: To obtain a high-resolution binding-energy spectrum for the ${}^{9}\mathrm{Be}(e,{e}^{\ensuremath{'}}{K}^{+})_{\ensuremath{\Lambda}}^{9}\mathrm{Li}$ reaction.Method: Electroproduction of the hypernucleus $_{\ensuremath{\Lambda}}^{9}\mathrm{Li}$ has been studied for the first time with sub-MeV energy resolution in Hall A at Jefferson Lab on a $^{9}\mathrm{Be}$ target. In order to increase the counting rate and to provide unambiguous kaon identification, two superconducting septum magn…
Structure of 106In nucleus
1990
Abstract Single-γ, γγ-coincidence, and γ-ray angular distribution spectra of the 106Cd(p, nγ)106In reaction were measured with Ge(HP), Ge(Li), and Ge(LEPS) detectors at various bombarding proton energies between 8 and 11 MeV. Altogether 141 (among them 117 new) transitions have been assigned to 106In. The conversion electrons were studied with an intermediate-image magnetic spectrometer plus Si(Li) detector, as well as with a superconducting magnetic lens combined with a Si(Li) detector. Internal conversion coefficients have been determined for 22 transitions. A more complete level scheme of 106In, containing 49 levels below 1650 keV excitation energy, has been proposed. On the basis of the…
Spectral broadening by spatial effects in X-ray microcalorimeters with superconducting absorber and NTD-Ge thermal sensor
2004
We discuss how the sensitivity to the position of absorption of the photons can affect the spectral resolution of X-ray microcalorimeters with superconducting Sn absorber and NTD-Ge thermal sensor. Data obtained through the computer simulations are reported for microcalorimeters with different geometries and phonon transmission probabilities at the interface between the absorber and thermistor.
Intercalation effect on hyperfine parameters of Fe in FeSe superconductor with Tc = 42 K
2015
57Fe-Mossbauer spectra of superconducting beta-FeSe, the Li/NH3 intercalate product and a subsequent sample of this intercalate treated with moist He gas have been measured in temperature range 4.7 - 290 K. A correlation is established between hyperfine parameters and critical temperature Tc in these phases. A strong increase of isomer shift upon intercalation is explained by a charge transfer from the Li/NH3 intercalate to the FeSe layers resulting in an increase of Tc up to 42 K. A significant decrease of the quadrupole splitting above 240 K has been attributed to diffusive motion of Li+ ions within the interlamellar space.
Time-domain analysis of electronic spectra in superfluid 4He
2004
Abstract Electronic absorption spectra of impurities in superfluid helium is developed in time domain, using time-dependent density functional theory to describe liquid 4 He and time-dependent perturbation theory to describe the electronic degrees of freedom of the impurity. Angularly isotropic potentials are used to describe the molecule–helium interactions in the ground and excited electronic states. The calculations rationalize experimentally observed phonon side-bands in 4 He droplets and in bulk helium, and allow assignments of spectral features to specific motions of the liquid.
Kernel-based retrieval of atmospheric profiles from IASI data
2011
This paper proposes the use of kernel ridge regression (KRR) to derive surface and atmospheric properties from hyperspectral infrared sounding spectra. We focus on the retrieval of temperature and humidity atmospheric profiles from Infrared Atmospheric Sounding Interferometer (MetOp-IASI) data, and provide confidence maps on the predictions. In addition, we propose a scheme for the identification of anomalies by supervised classification of discrepancies with the ECMWF estimates. For the retrieval, we observed that KRR clearly outperformed linear regression. Looking at the confidence maps, we observed that big discrepancies are mainly due to the presence of clouds and low emissivities in de…