Search results for "Emission spectroscopy"
showing 10 items of 180 documents
Electronic and magnetic properties of Mn 12 molecular magnets on sulfonate and carboxylic acid prefunctionalized gold surfaces
2012
Structural, electronic, and magnetic properties of [Mn 12O 12(bet) 16(EtOH) 4](PF 6) 14·4CH 3CN·H 2O (in short Mn 12bet, bet = betaine = +N(CH 3) 3-CH 2-COO -) single-molecule magnets (SMMs) deposited on previously functionalized gold surfaces have been investigated. Self-assembled monolayers (SAMs) either of sodium mercaptoethanesulfonate (MES) or mercaptopropionic acid (MPA) are used as functionalization to avoid the direct interaction between the Mn 12bet molecules and the Au surface with the aim of preserving the main functional properties of the molecules. Scanning tunneling microscopy (STM) and X-ray photoemission spectroscopy (XPS) analysis show deposited Mn 12bet SMMs well-isolated …
Plasma diagnostic tools for ECR ion sources : What can we learn from these experiments for the next generation sources
2019
International audience; The order-of-magnitude performance leaps of ECR ion sources over the past decades result from improvements to the magnetic plasma confinement, increases in the microwave heating frequency, and techniques to stabilize the plasma at high densities. Parallel to the technical development of the ion sources themselves, significant effort has been directed into the development of their plasma diagnostic tools. We review the recent results of Electron Cyclotron Resonance Ion Source (ECRIS) plasma diagnostics highlighting a number of selected examples of plasma density, electron energy distribution, and ion confinement time measurements, obtained mostly with the second-gener…
Effect of organic matrices on the determination of the trace element chemistry (Mg, Sr, Mg/Ca, Sr/Ca) of aragonitic bivalve shells (<i>Arctica …
2010
The element chemistry of biogenic carbonates can provide important data on past environments. However, the Sr/Ca and Mg/Ca ratios as well as the Mg and Sr concentrations of biological carbonates, especially aragonitic bivalves often depart from apparent thermodynamic equilibrium. When measured in situ by means of LA-ICP-MS, the Mg concentration is often substantially enriched (two- to threefold) near the organic-rich, annual growth lines. To test the hypothesis that some organic components exert a major influence on the skeletal metal content, the element chemistry of different shell components (insoluble organic matrix, IOM; dissolved CaCO3 and soluble organics, SOM) of Arctica islandica w…
Geometric and electronic structure of dithiapyranylidine: evolution upon oxidation
1993
Abstract We present a theoretical investigation of the modifications that successive oxidation induces on the geometric and electronic structures of the π-electron donor dithiapyranylidene. The lengthening of the double bonds and the shortening of the single bonds calculated as the molecular charge increases indicate a gain of aromaticity with oxidation. Both the geometricand the electronic structure of dithiapyranylidene show a clear evolution towards those of biphenyl as oxidation takes place.
Inductively coupled plasma atomic emission spectrometric determination of arsenic in mussel products
1993
A precise, accurate procedure is proposed for the determination of arsenic in mussel products by inductively coupled plasma atomic emission spectrometry. Organic matter is destroyed by dry ashing. Experimental conditions for the determination of arsenic were selected and an interference study was carried out. The methodology developed has a detection limit of 0.1 μg g−1, a relative standard deviation of 3%, and a recovery percentage of 98±2%. The accuracy of the method was checked by analysis of a certified sample of NIST oyster tissue (certified 14.0±1.2 μg g−1; found 14.1±1.1 μg g−1). The proposed procedure was used to analyze real samples of mussel products.
Amorphous Complexes MM (EDTA) (H2O)4 · 2H2O . LAXS and XPS Investigation of the Local Structure
1988
Abstract The amorphous MM (EDTA)(H2O)4·2 H2O (M = Ni,Co) substances are made up of infinite chains of alternating "hydrated" and "chelated" octahedra bridged by carboxylate groups: M(H2O)4 - M(EDTA)-M(H2O)4-... . XPS enables to ascertain that the coordination of the EDTA ligand in the amorphous phase is identical to that in the crystalline phase, i.e., hexacoordination toward the M atom and two bridging groups in the Ni -Ni, Co - Co compounds.
A study of VUV emission and the extracted electron-ion ratio in hydrogen and deuterium plasmas of a filament-driven H−/D− ion source
2019
Vacuum ultraviolet (VUV) emission diagnostics for studying differences of electron impact processes in hydrogen and deuterium plasmas are presented. The method is applied to study a filament driven multicusp arc discharge negative ion source by comparing the VUV-emission intensities of different emission bands and extracted currents of H−/D− ions and electrons. It was found that the ratio of coextracted electrons to extracted ions is four times higher for deuterium than for hydrogen. No significant differences of the VUV-spectra or volumetric rates of ionization, excitation, production of high vibrational states, and dissociation were found between the plasmas of the two isotopes. The volum…
Hartree-Fock calculations and photoelectron spectra of SSO and NSF
1974
Results from ab initio Hartree-Fock calculations on the ground states of SSO and NSF are reported. The calculations employ large basis sets of Gaussian functions of essentially double zeta quality. The photoelectron spectra of the bent triatomic molecules with 18 valence electrons, i.e. SSO, NSF, O3, SO2, NSCl are compared. Further experimental details of the photoelectron spectrum of SSO are presented and an assignment of the observed ionic states of SSO⊕ is attempted. The calculated dissociation energies, dipole moments and the population analyses are given. The correlation effect is qualitatively discussed in connection with the applicability of Koopmans' theorem for the bent tri-atomic …
Embedded-atom calculations of Auger and x-ray photoemission shifts for metallic elements
1982
Change in self-consistent-field energy density-functional calculations are reported for Auger and core-level binding-energy shifts in sp-bonded metals. The basic model, atom in jellium vacancy, gives good agreement with experiment, especially in the Auger case. The chemical and relaxation contributions to the shifts are discussed, and the extra-atomic response is analyzed in detail, both in position and energy space. The adequacy of the "excited-atom" approach to the energy shifts is discussed. Peer reviewed
An X-ray characterization of the central region of the supernova remnant G332.5-5.6
2015
Aims. We present an X-ray analysis of the central region of supernova remnant (SNR) G332.5-5.6 through an exhaustive analysis of XMM-Netwon observations with complementary infrared observations. We characterize and discuss the origin of the observed X-ray morphology, which presents a peculiar plane edge over the west side of the central region. Methods. The morphology and spectral properties of the X-ray SNR were studied using a single full frame XMM-Netwon observation in the 0.3 to 10.0 keV energy band. Archival infrared WISE observations at 8, 12 and 24 μm were also used to investigate the properties of the source and its surroundings at different wavelengths. Results. The results show th…