Electron Energy Loss Near Edge Structure Spectra Research Articles

RETRACTED: The post-peak spectra in electron energy loss near edge structure

The origin of post-peak spectra in electron energy loss near edge structure (ELNES) spectra of pure Ni and NiO is investigated through ab initio calculation. Contrary to the general view that post-peak spectra in ELNES are generated by transitions to continuum states, it is found that orbit hybridization is the main cause of post-peak spectra in the low energy range above the Fermi level based on the calculation of electronic structure and ELNES. Reasons for the intensity differences of the simulated and experimental spectra are discussed. This work contributes to the understanding of ELNES and to the quantification of ELNES spectra.

Theoretical ELNES spectra of Si-K, Si-L, N-K, and O-K edges of an intergranular glassy film model in β-Si3N4

A realistic atomic model of an intergranular glassy film (IGF) between the prismatic faces of crystalline β-Si3N4 has been used for ab initio exploration of variations in electron energy loss near edge structure (ELNES) spectral response from each of the component elements and available edges. The computed ELNES spectra within the IGF region show substantial variability that sometimes defy expectation. Upon careful analysis, we have devised guidelines for comparison and interpretation of the spectra in terms of the local coordination and bonding environment. The bond lengths, bond angles, coordination number, and elemental types of the bonded atoms cannot be relied upon to systematically explain the computed variations. It is anticipated that the rise of ELNES spectral measurements with enhanced spatial and energy resolution that are performed in conjunction with atomic scale imaging techniques will require new methods to interpret observed results. The intent of this work is to make progress and stimulate others in that direction.

Spectroscopic imaging of electron energy loss spectra using ab initio data and function field visualization

We have devised a technique for spectral imaging using accurate ab initio electron energy loss near edge structure (ELNES) data and function field visualization. The technique is initially applied to a planar defect model in Si with different ring structures and no broken bonds where experimental probes are severely limited. The same model with B doping is also considered. It is shown that specific deviations in different energy ranges of the ELNES spectra are correlated with different structural components of the models.

Manifestation of incommensurate structural modulations in the Ti- L 2,3 electron energy-loss near-edge structure of Sr2TiSi2O8

Structural modulations hosted by complex oxides are–beyond relative orientation changes of ‘rigid units’–accompanied by characteristic distortions of coordination polyhedra. Electronic structure calculations in the local density approximation, performed at model clusters derived from positionally modulated structures, proved that the molecular–orbital structure also sensitively reflects such distortions. The latter crystal-field splitting of unoccupied states is accessible by high-resolution electron energy-loss near-edge structure (ELNES) spectroscopy. However, since ELNES spectra average over many different individual target-ion environments, the resulting ELNES possesses significantly broadened spectral features. In this contribution, such broadening is shown to dramatically influence the spectral shape of the Ti-L 2,3 ELNES acquired at the strongly modulated fresnoite framework compound Sr2TiSi2O8.

ELNES analysis for silicon, silicon oxide and their interface

We have measured and analyzed Si L23-edge electron energy loss near edge structure (ELNES) spectra for silicon, silicon oxide and their interface. ELNES spectra have been recorded by a combination of high resolution electron energy loss spectroscopy and an installed slit built in a 300 keV transmission electron microscope. The projected slit allows us to have signals about each 0.7 nm width area of the specimen. These spectra change site by site from Si to SiO2. With the aid of multiple scattering calculations, we have discussed the local structure near the interface.

Chemical bonding state at grain boundaries in BaTiO3 doped with a small amount of cation

The chemical bonding state at grain boundaries was examined with electronenergy-loss spectroscopy in BaTiO3 doped with a small amount of cations at a level of 0.001. In contrast with A-site excess compounds, the oxygen K-edge electron energy-loss near-edge structure spectra were different for grain interiors and for grain boundaries in B-site excess compounds. The difference is explained in terms of the linkage of TiO6 octahedra at grain boundaries in the B-site excess BaTiO3.