Inner shell spectroscopy of (η5-C5H5)2TiCl2, (η5-C5H5)TiCl3, and TiCl4

1993 ◽  
Vol 71 (10) ◽  
pp. 1632-1644 ◽  
Author(s):  
A.T. Wen ◽  
A.P. Hitchcock
Keyword(s):  
Energy Loss ◽  
Gas Phase ◽  
Electric Dipole ◽  
Oscillator Strengths ◽  
Extended Hückel ◽  
Cyclopentadienyl Complexes ◽  
Dipole Scattering ◽  
Electron Energy Loss ◽  
Extended Hückel Calculations ◽  
Electron Energy Loss Spectra

Oscillator strengths for C 1s excitation of gas phase Cp2TiCl2 and CpTiCl3 (Cp = η5-C5H5), and Cl 2p and Ti 2p excitation of gas phase Cp2TiCl2, CpTiCl3, and TiCl4 have been derived from electron energy loss spectra recorded under electric dipole scattering conditions. The C 1s spectra are interpreted with the aid of semiempirical extended Hückel calculations and comparisons with the C 1s spectra of other cyclopentadienyl complexes. The Ti 2p spectra are interpreted using the extended Hückel results and comparisons with atomic multiplet–crystal field calculations for Ti4+ taken from the literature.

Electron energy-loss spectra of fullerene C60 in the gas phase

1993 ◽  
Vol 209 (5-6) ◽  
pp. 434-438 ◽  
Author(s):  
Christophe Bulliard ◽  
Michael Allan ◽  
Sydney Leach
Keyword(s):  
Energy Loss ◽  
Gas Phase ◽  
Electron Energy ◽  
Fullerene C60 ◽  
Electron Energy Loss ◽  
Electron Energy Loss Spectra

Inner shell electron-energy loss spectroscopy of some heterocyclic molecules

1986 ◽  
Vol 64 (6) ◽  
pp. 1145-1155 ◽  
Author(s):  
D C Newbury ◽  
I Ishii ◽  
A P Hitchcock
Keyword(s):  
Energy Loss ◽  
Electron Energy ◽  
Small Angle ◽  
Electric Dipole ◽  
Electron Energy Loss Spectroscopy ◽  
Bond Lengths ◽  
Heterocyclic Molecules ◽  
Valence States ◽  
Dipole Scattering ◽  
Electron Energy Loss

The carbon K-shell spectra of gaseous furan, pyrrole, tetrahydrofuran, pyrrolidine, tetrahydropyran, and piperidine have been recorded by electron energy loss spectroscopy (ISEELS) under electric dipole scattering conditions (2.5 keV impact, small angle.) The spectra are dominated by transitions to unoccupied valence states of π and σ symmetry. Features attributed to transitions to π*(CH2) levels are consistently observed below the ionization threshold in the spectra of the saturated species. the positions of continuum features are generally in agreement with a previously documented correlation with bond lengths. Additional weak continuum features are observed in the smaller saturated heterocyclic species which are ascribed to delocalized σ* states.

scholarly journals The σ* molecular orbitals of perfluoroalkanes as studied by inner-shell electron energy loss and electron transmission spectroscopies

1988 ◽  
Vol 66 (8) ◽  
pp. 2104-2121 ◽  
Author(s):  
I. Ishii ◽  
R. McLaren ◽  
A. P. Hitchcock ◽  
K. D. Jordan ◽  
Y. Choi ◽  
...  
Keyword(s):  
Energy Loss ◽  
Electron Energy ◽  
Inductive Effect ◽  
Oscillator Strengths ◽  
Negative Ion ◽  
Electron Transmission ◽  
Ultraviolet Excitation ◽  
Shell Electron ◽  
Electron Energy Loss ◽  
Electron Energy Loss Spectra

Absolute oscillator strength spectra in the C 1s (280–340 eV) and F 1s (680–740 eV) regions of the perfluoro-n-alkanes from C2 to C6 and perfluorocycloalkanes from C3 to C6 have been determined from inner-shell electron energy loss spectra recorded under electric-dipole scattering conditions. The spectral features are interpreted in terms of spatially localized transitions terminating at orbitals of predominantly σ*(C—F) and σ*(C—C) character. When compared to the spectra of the perfluoro-n-alkanes, both the C 1s and F 1s spectra of the perfluorocycloalkanes exhibit additional low-lying bands which are assigned to transitions terminating at σ*(C—C) orbitals which are shifted to low energy by the combination of the strain of cyclization and the inductive effect of the fluorination. The electron transmission spectra of selected perfluorocycloalkanes (which provide information on their anion states) show as well that the electron affinities of the cyclic systems are substantially lower than those of the corresponding perfluoro-n-alkanes, again as a result of a low-lying σ* orbital in the cyclic species. Quantum chemical calculations of the alkane and perfluoroalkane ground-state orbital structures support the experimental results. The localized character of the inner-shell excitations, indicated by the constancy of both term values and oscillator strengths with increasing chain length, contrasts with the more delocalized character of the states accessed in ultraviolet excitation or negative ion formation.

Background Fitting in the Low-Loss Region of Electron Energy Loss Spectra

1990 ◽  
Vol 48 (2) ◽  
pp. 56-57
Author(s):  
C P Scott ◽  
A J Craven ◽  
C J Gilmore ◽  
A W Bowen
Keyword(s):  
Energy Loss ◽  
Multiple Scattering ◽  
Simple Form ◽  
Single Scattering ◽  
Low Loss ◽  
Characteristic Energy ◽  
Normal Method ◽  
Fitting In ◽  
Electron Energy Loss ◽  
Electron Energy Loss Spectra

The normal method of background subtraction in quantitative EELS analysis involves fitting an expression of the form I=AE-r to an energy window preceding the edge of interest; E is energy loss, A and r are fitting parameters. The calculated fit is then extrapolated under the edge, allowing the required signal to be extracted. In the case where the characteristic energy loss is small (E < 100eV), the background does not approximate to this simple form. One cause of this is multiple scattering. Even if the effects of multiple scattering are removed by deconvolution, it is not clear that the background from the recovered single scattering distribution follows this simple form, and, in any case, deconvolution can introduce artefacts.The above difficulties are particularly severe in the case of Al-Li alloys, where the Li K edge at ~52eV overlaps the Al L2,3 edge at ~72eV, and sharp plasmon peaks occur at intervals of ~15eV in the low loss region. An alternative background fitting technique, based on the work of Zanchi et al, has been tested on spectra taken from pure Al films, with a view to extending the analysis to Al-Li alloys.

ELNES of Iron Compounds

1990 ◽  
Vol 48 (2) ◽  
pp. 28-29
Author(s):  
Hiroki Kurata ◽  
Kazuhiro Nagai ◽  
Seiji Isoda ◽  
Takashi Kobayashi
Keyword(s):  
Energy Loss ◽  
Metal Ions ◽  
Energy Resolution ◽  
Transition Metal Oxides ◽  
Local Symmetry ◽  
Iron Compounds ◽  
Fine Structures ◽  
Electron Energy Loss ◽  
Fe Ions ◽  
Electron Energy Loss Spectra

Electron energy loss spectra of transition metal oxides, which show various fine structures in inner shell edges, have been extensively studied. These structures and their positions are related to the oxidation state of metal ions. In this sence an influence of anions coordinated with the metal ions is very interesting. In the present work, we have investigated the energy loss near-edge structures (ELNES) of some iron compounds, i.e. oxides, chlorides, fluorides and potassium cyanides. In these compounds, Fe ions (Fe2+ or Fe3+) are octahedrally surrounded by six ligand anions and this means that the local symmetry around each iron is almost isotropic.EELS spectra were obtained using a JEM-2000FX with a Gatan Model-666 PEELS. The energy resolution was about leV which was mainly due to the energy spread of LaB6 -filament. The threshole energies of each edges were measured using a voltage scan module which was calibrated by setting the Ni L3 peak in NiO to an energy value of 853 eV.

Parallel Detection of Electron Energy Loss Spectra in Direct Mode

1990 ◽  
Vol 48 (2) ◽  
pp. 82-83
Author(s):  
Eckhard Quandt ◽  
Stephan laBarré ◽  
Andreas Hartmann ◽  
Heinz Niedrig
Keyword(s):  
Energy Loss ◽  
Electron Energy ◽  
Energy Resolution ◽  
Large Angle ◽  
Maximum Energy ◽  
Semiconductor Detectors ◽  
Parallel Detection ◽  
Photodiode Arrays ◽  
Electron Energy Loss ◽  
Electron Energy Loss Spectra

Due to the development of semiconductor detectors with high spatial resolution -- e.g. charge coupled devices (CCDs) or photodiode arrays (PDAs) -- the parallel detection of electron energy loss spectra (EELS) has become an important alternative to serial registration. Using parallel detection for recording of energy spectroscopic large angle convergent beam patterns (LACBPs) special selected scattering vectors and small detection apertures lead to very low intensities. Therefore the very sensitive direct irradiation of a cooled linear PDA instead of the common combination of scintillator, fibre optic, and semiconductor has been investigated. In order to obtain a sufficient energy resolution the spectra are optionally magnified by a quadrupole-lens system.The detector used is a Hamamatsu S2304-512Q linear PDA with 512 diodes and removed quartz-glas window. The sensor size is 13 μm ∗ 2.5 mm with an element spacing of 25 μm. Along with the dispersion of 3.5 μm/eV at 40 keV the maximum energy resolution is limited to about 7 eV, so that a magnification system should be attached for experiments requiring a better resolution.

Apparent oscillator strengths for molecular oxygen derived from electron energy‐loss measurements

1975 ◽  
Vol 63 (1) ◽  
pp. 241-248 ◽  
Author(s):  
Russell H. Huebner ◽  
R. J. Celotta ◽  
S. R. Mielczarek ◽  
C. E. Kuyatt
Keyword(s):  
Energy Loss ◽  
Molecular Oxygen ◽  
Electron Energy ◽  
Oscillator Strengths ◽  
Electron Energy Loss
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