Search results for "Emission spectroscopy"
showing 10 items of 180 documents
Example of a technique for evaluation of interferences caused by complicated sample matrix elements in ICP-AES determination
2001
An example of a useful and rapid procedure for the evaluation of interferences caused by complicated sample matrices in inductively coupled plasma atomic emission spectrometry (ICP-AES) is described. Using simple acid-base standards, all the elements investigated were determined separately in complicated matrices with satisfactory results. Multiple linear regression was used to calculate the linear correction coefficients for each matrix element analyzed. Good analytical results improved still further when this correction method was used.
Photoelectron spectrum of poly(methyl-n-propylsilane): a valence band theoretical interpretation
1996
Abstract The results of a theoretical investigation of the photoelectron spectrum of poly(methyl-n-propylsilane) are reported. The simulation of the UPS spectrum has been obtained from band structure calculations performed using the valence effective Hamiltonian method (VEH). The theoretical spectrum is fully consistent with the experimental UPS spectrum, and an excellent quantitative agreement is observed when the energies of the main peaks of both spectra are compared. A complete analysis of the contributions to the main peaks, together with a detailed interpretation of all the photoemission bands observed in the experimental spectrum have also been performed.
Anomalous d-like surface resonances on Mo(110) analyzed by time-of-flight momentum microscopy.
2015
The electronic surface states on Mo(110) have been investigated using time-of-flight momentum microscopy with synchrotron radiation (hν=35 eV). This novel angle-resolved photoemission approach yields a simultaneous acquisition of the E-vs-k spectral function in the full surface Brillouin zone and several eV energy interval. (kx,ky,EB)-maps with 3.4 A(-1) diameter reveal a rich structure of d-like surface resonances in the spin-orbit induced partial band gap. Calculations using the one-step model in its density matrix formulation predict an anomalous state with Dirac-like signature and Rashba spin texture crossing the bandgap at Γ¯ and EB=1.2 eV. The experiment shows that the linear dispersi…
Simultaneous determination of hydride and non-hydride forming elements by inductively coupled plasma optical emission spectrometry
2011
e percentagens de recuperacao entre 97 e 103%. A aplicabilidade do sistema foi demonstrada na determinacao simultânea de Ca, Cd, Co, Cr, Cu, Fe, Mg, Mn, Mo, Ni, Zn, As, Bi, Sb, Se e Te em amostras certificadas para elementos tracos, NIST 1549 (leite em po desnatado), NIST 1570a (folhas de espinafre), DORM-2 (musculo de cacao) e TORT-2 (hepatopâncreas de lagosta). Os resultados obtidos foram concordantes com os teores certificados. The operating characteristics of a dual nebulization system were studied including instrumental and chemical conditions for the hydride generation and analytical figures of merit for both, hydride and non hydride forming elements. Analytical performance of the neb…
Development and Optimization of Pre-Concentration Procedure of Rare-Earth Elements (REEs) in Their Minerals, Using Microwave - Assisted Sample Dissol…
2015
Abstract The aim of this research was to develop and optimize a procedure for determination of REEs in xenotime and monazite samples collected from Bangka Island, which were compared to Standard Monazite (71 AG) of Bureau of Analyzed Samples, London. ICP-OES method was used for the determination. The samples were dried and sterilized by heating for a week at 110 °C, before digesting with nitric acid and hydrofluoric acid, using a microwave-assisted digestion system. After a careful line selection, at the detection limits for all REEs in the ng/mL the REEs were reliably obtained at the 0.09 – 38% level.
Real-space multiple scattering method for angle-resolved photoemission and valence-band photoelectron diffraction and its application to Cu(111)
2011
Abstract: A computational method is presented for angle-resolved photoemission spectra (ARPES) and photoelectron diffraction (PED) in the ultraviolet regime. The one-step model is employed and both initial valence and final continuum states are calculated using the finite-cluster, real-space multiple scattering method. Thereby the approach is versatile and provides a natural link to core-level PED. The method is applied to the Cu(111) valence band and good agreement with experiment is found for both ARPES spectra and PED patterns. When the PED patterns are integrated over a filled band of a single-orbital symmetry, such as Cu-3d, we show, both numerically and analytically, that the exact th…
DICHROISM IN ANGLE-RESOLVED PHOTOEMISSION FROM Pt(111)
2002
The angular dependence of the circular dichroism in photoemission from Pt(111) was investigated for excitation with VUV and soft X-ray radiation. VUV excitation was used to probe band structure and the circular dichroism for valence band emission. The measurements are compared to full relativistic single step photoemission calculations. XPS was used to investigate the circular dichroism in emission from the 4f core level. In this case, the dichroism is induced by photoelectron diffraction. First results from single step core level calculations are compared to the experimental observations.
Elektrónová a pásová štruktúra CuMnAs študovaná optickou a fotoemissinou spektroskopiou
2017
Tetragonal phase of CuMnAs progressively appears as one of the key materials for antiferromagnetic spintronics due to efficient current-induced spin-orbit torques whose existence can be directly inferred from crystal symmetry. Theoretical understanding of spintronic phenomena in this material, however, relies on the detailed knowledge of electronic structure (band structure and corresponding wave functions) which has so far been tested only to a limited extent. We show that AC permittivity (obtained from ellipsometry) and UV photoelectron spectra agree with density functional calculations. Together with the x-ray diffraction and precession electron diffraction tomography, our analysis confi…
Probing bulk electronic structure with hard X-ray angle-resolved photoemission.
2010
Traditional ultraviolet/soft X-ray angle-resolved photoemission spectroscopy (ARPES) may in some cases be too strongly influenced by surface effects to be a useful probe of bulk electronic structure. Going to hard X-ray photon energies and thus larger electron inelastic mean-free paths should provide a more accurate picture of bulk electronic structure. We present experimental data for hard X-ray ARPES (HARPES) at energies of 3.2 and 6.0 keV. The systems discussed are W, as a model transition-metal system to illustrate basic principles, and GaAs, as a technologically-relevant material to illustrate the potential broad applicability of this new technique. We have investigated the effects of …
Temperature and doping dependence of normal state spectral properties in a two-orbital model for ferropnictides
2016
Using a second-order perturbative Green's functions approach we determined the normal state single-particle spectral function $A(\vec{k},\omega)$ employing a minimal effective model for iron-based superconductors. The microscopic model, used before to study magnetic fluctuations and superconducting properties, includes the two effective tight-binding bands proposed by S.Raghu et al. [Phys. Rev. B 77, 220503 (R) (2008)], and intra- and inter-orbital local electronic correlations, related to the Fe-3d orbitals. Here, we focus on the study of normal state electronic properties, in particular the temperature and doping dependence of the total density of states, $A(\omega)$, and of $A(\vec{k},\o…