Search results for "Absorption"
showing 10 items of 2701 documents
X-ray absorption spectroscopy studies of the off-center Ni2+ions in Ni c Mg 1-c O solid solutions
1996
In this work we present the x-ray absorption spectroscopy study of NicMg1-cO (0.01 <EQ c <EQ 1) solid solutions. The extended x-ray absorption fine structure (EXAFS) above the Ni K-edge was analyzed using the multi-shell fitting procedure. It was found that nickel ions are located in a distorted environment and shift upon dilution to the off- center positions. This fact follows from two main results: (1) in the first shell, the average Ni- O distance increases linearly upon dilution; (2) in the second shell, the average Ni-Ni distance remains unchanged and decreases slightly at low nickel concentration while the dependence of the Ni-Mg distance has a break at c approximately equals 0.6 and …
A tetranuclear organorhenium(i) complex of the 2,3,5,6-tetrafluoro-7,7,8,8-tetracyano-p-quinodimethane radical anion, TCNQF4˙−
2008
The radical complex {(mu(4)-TCNQF4)[Re(CO)(3)(bpy)](4)}(PF(6))(3), as prepared and isolated from the reaction between TCNQF4 and [Re(CO)(3)(bpy)(MeOH)](PF(6)), was studied electrochemically and by IR vibrational spectroscopy, UV-Vis-NIR absorption spectroscopy, and by EPR at 9.5, 190 and 285 GHz. The isotropic g factor of 2.0058, the detectable g anisotropy, and the (185,187)Re EPR hyperfine coupling of 0.95 mT for four equivalent metal nuclei support predominant, but not exclusive, spin localisation at the bridging ligand. Nitrile and metal carbonyl stretching frequencies as well as the typically structured near infrared absorption band lend further support to (TCNQF4 (-))(Re(I))(4) as the…
Mn, Fe, Zn and As speciation in a fast-growing ferromanganese marine nodule
2004
The speciation of Mn, Fe, As and Zn in a fast-growing (0.02mm/yr), shallow-marine ferromanganese nodule has been examined by micro X-ray fluorescence, micro X-ray diffraction, and micro X-ray absorption spectroscopy. This nodule exhibits alternating Fe-rich and Mn-rich layers reflecting redox variations in water chemistry. Fe occurs as two-line ferrihydrite. The As is strictly associated with Fe and is mostly pentavalent, with an environment similar to that of As sorbed on or coprecipitated with synthetic ferrihydrite. The Mn is in the form of turbostratic birnessite with ~;10 percent trivalent manganese in the layers and probably ~;8 percent corner-sharing metal octahedra in the interlayer…
Moisture absorption, thermal conductivity and noise mitigation of clay based plasters: The influence of mineralogical and textural characteristics
2016
Abstract Three pre-mixed clay based plasters successfully employed in green building practices in several European countries (Spain, France, Germany, and United Kingdom), mainly used for interior wall coating and finishing, were tested in this paper. Their compositional and textural characteristics as well as plastic behaviour were investigated through a multi-analytical approach in a previous paper. A natural earth (Terra Rossa red soil sampled in north-western Sicily), theoretically appropriate for the production of earthen plaster, was also subjected to the same analytical routine and compared with the three commercially available products. Humidity control capacity by the determination …
2D+1 spatial solitons in heavy metal oxide glass
2007
Two-dimensional self-confinement of near-infrared picosecond pulsed beams is demonstrated in a novel heavy metal-oxide glass, three-photon absorption being the stabilization mechanism to prevent catastrophic collapse.
Determination of third-order nonlinear optical properties of ABI derivatives
2019
This material is based upon work supported by the ERDF 1.1.1.1 activity project Nr. 1.1.1.1/16/A/046 “Application assessment of novel organic materials by prototyping of photonic devices”.
Determination of Kerr and two-photon absorption coefficients of ABI thin films
2018
This material is based upon work supported by the ERDF 1.1.1.1 activity project Nr. 1.1.1.1/16/A/046 “Application assessment of novel organic materials by prototyping of photonic devices”
Stabilization of solutions of the filtration equation with absorption and non-linear flux
1995
This paper is primarily concerned with the large time behaviour of solutions of the initial boundary value problem $$\begin{gathered} u_t = \Delta \phi (u) - \varphi (x,u)in\Omega \times (0,\infty ) \hfill \\ - \frac{{\partial \phi (u)}}{{\partial \eta }} \in \beta (u)on\partial \Omega \times (0,\infty ) \hfill \\ u(x,0) = u_0 (x)in\Omega . \hfill \\ \end{gathered} $$ Problems of this sort arise in a number of areas of science; for instance, in models for gas or fluid flows in porous media and for the spread of certain biological populations.
Radiation effects in Li2B4O7 oxide crystals
2000
Abstract The lithium tetraborate single crystal has been irradiated by neutrons and the optical properties of these crystals are studied. Irradiation induces optical absorption bands at 42 000, 33 000, and 20 000 cm −1 . The intensities of these bands depend on the energy of the neutrons, on the irradiation temperature, and on the presence of an external electric field. An applied electric field induces the displacement of charged particles, creating the micrononhomogeneous regions in the crystal leading to a decrease of the intensities of the absorption bands. It has been established that the irradiation damages not only the surface of the crystal but also the deeper layers.
Thorium partitioning in Greek industrial bauxite investigated by synchrotron radiation and laser-ablation techniques
2011
Abstract Typical red–brown (Fe-rich) and high-quality white–grey (Fe-depleted) bauxite samples from active mines of the Parnassos-Ghiona area, central Greece, were investigated. According to XRF and ICP-MS analyses their actinide content, and particularly of Th, is relatively increased. Fe-depleted samples contain up to 62.75 ppm Th corresponding to 220 Bq/kg due to 228Ac (232Th-series), whereas Fe-rich samples are less Th-radioactive (up to 58.25 ppm Th, 180 Bq/kg due to 228Ac). Powder-XRD patterns showed that Th-enriched (Fe-depleted) bauxite consists mostly of diaspore (AlOOH polymorph), anatase and rutile (TiO2 polymorphs). SEM-EDS indicated the presence of Ti–Fe–containing phases (e.g.…