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Articles you may be interested inNitrogen K-edge X-ray absorption near edge structure (XANES) spectra of purine-containing nucleotides in aqueous solution Thioethanol on Cu(111) at room temperature: A near edge x-ray absorption fine structure and x-ray photoelectron spectroscopy study Influence of ligands on the xray absorption nearedge structure of palladium(II) complex compounds J. Chem. Phys. 85, 5269 (1986); 10.1063/1.451668 Xray absorption near edge structure (XANES) of PtCl2− 4 in solid and solution environmentsWe have studied the Cu binding site in Cu(II)-ATP, Cu(II)-tripolyphosphate, and Cu(II)-D-ribose complexes in aqueous solution at several pH values ranging froni 3 to 12 by means of high-resolution x-ray spectroscopy. We have measured the spectra in the x-ray absorption near edge structure (XANES) region to probe the tetragonal distortion of the Cu site in these compounds, as indicated by optical d-d spectroscopy. The spectrophotometric studies proposed that Cu(II) bind to the oxygen atoms of the phosphate groups of ATP with a distorted octahedral symmetry at low pH, while at high pH, the metal atom would be bound to the hydroxyl groups of the ribose moiety with an almost planar symmetry. We have compared the measured XANES spectra with multiple scattering calculations, by using as a structural model a simple tetragonal Cu06 cluster with fixed equatorial distance (1.95 A) and variable axial distance (1.95-2.7 A). The multiple scattering calculations fit well the experimental data of Cu-A TP in solution, and allow us to solve the different contribution in the XANES spectrum from axial and equatorial distances. The best agreement is obtained with values of the axial distance of 2.2 A at low pH, and 2.7 A at high pH. Our result indicates that an increasing percentage of highly distorted (square-plane) Cu site is present at high pH, and confirm the d-d spectroscopic model.

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Ultrashort-pulse, laser-produced plasmas have become very interesting laboratory sources to study spectroscopically due to their very high densities and temperatures, and the high laser-induced electromagnetic fields present. Typically, these plasmas are of very small volume and very low emissivity. Thus, studying these near point source plasmas requires advanced experimental techniques. We present a new spectrometer design called the focusing spectrometer with spatial resolution (FSSR-2D) based on a spherically bent crystal which provides simultaneous high spectral (λ/Δλ≈104) and spatial resolution (≈10 μm) as well as high luminosity (high collection efficiency). We described in detail the FSSR-2D case in which a small, near point source plasma is investigated. An estimate for the spectral and spatial resolution for the spectrometer is outlined based on geometric considerations. Using the FSSR-2D instrument, experimental data measured from both a 100 fs and a nanosecond pulse laser-produced plasma are presented.

We have investigated the evolution in the heteroepitaxy of InP on InGaP/GaAs (0 0 1) layers from the initial formation of a strained wetting layer (WL) up to the development of quantum dots. Atomic force microscopy and RHEED as well as continuous and time-resolved photoluminescence measurements provide evidence of four main stages for InP growth evolution. Our results indicate that the InP dot formation occurs according to the Stranski-Krastanov growth mode coupled to a WL erosion mechanism driven by the spatially variable strain field present in the WL. Moreover, the correlation of morphological and optical data indicates the stability of dot shapes and interfaces in this system.