Le spectre des états électroniques de Kr I mesuré par spectrométrie électronique

1975 ◽  
Vol 53 (19) ◽  
pp. 2079-2084 ◽  
Author(s):  
A. Delage ◽  
J.-D. Carette
Keyword(s):  
Experimental Data ◽  
Energy Loss ◽  
Inelastic Scattering ◽  
Electronic States ◽  
Resolving Power ◽  
Electron Spectrometer ◽  
Energy Incident ◽  
First Time ◽  
Electron Energy Loss ◽  
Electron Energy Loss Spectra

The spectrum of electronic states of krypton I has been measured by inelastic scattering of monoenergetic electrons with the aid of an electron spectrometer which has a high resolving power, ΔE/E = 0.02. Electron energy loss spectra have allowed us to detect and identify numerous electronic states of krypton I for the first time by the means of this experimental method. The relative heights of the peaks corresponding to an energy loss, which are related to the probability of excitation of the atom by electron impact to a given state, have been measured from experimental data as a function of the energy incident electrons and as a function of the scattering angle.

scholarly journals Deconvolution of Overlapping Features in Electron Energy-loss Spectra: Determination of Absolute Differential Cross Sections for Electron-impact Excitation of Electronic States of Molecules

1997 ◽  
Vol 50 (3) ◽  
pp. 525 ◽  
Author(s):  
L. Campbell ◽  
P. J. O. Teubner ◽  
M. J. Brunger ◽  
B. Mojarrabi ◽  
D. C. Cartwright
Keyword(s):  
Energy Loss ◽  
Electron Energy ◽  
Cross Sections ◽  
Differential Cross ◽  
Electronic States ◽  
Impact Excitation ◽  
Spectroscopic Constants ◽  
Differential Cross Sections ◽  
Electron Energy Loss ◽  
Electron Energy Loss Spectra

A set of three computer programs is reported which allow for the deconvolution of overlapping molecular electronic state structure in electron energy-loss spectra, even in highly perturbed systems. This procedure enables extraction of absolute differential cross sections for electron-impact excitation of electronic states of diatomic molecules from electron energy-loss spectra. The first code in the sequence uses the Rydberg–Klein–Rees procedure to generate potential energy curves from spectroscopic constants, and the second calculates Franck–Condon factors by numerical solution of the Schrödinger equation, given the potential energy curves. The third, given these Franck–Condon factors, the previously calculated relevant energies for the vibrational levels of the respective electronic states (relative to the v″ = 0 level of the ground electronic state) and the experimental energy-loss spectra, extracts the differential cross sections for each state. Each program can be run independently, or the three can run in sequence to determine these cross sections from the spectroscopic constants and the experimental energy-loss spectra. The application of these programs to the specific case of electron scattering from nitric oxide (NO) is demonstrated.

Practical Materials Microanalysis by Electron Spectrometry

1977 ◽  
Vol 35 ◽  
pp. 244-247
Author(s):  
David C. Joy ◽  
Dennis M. Maher
Keyword(s):  
Electron Microscope ◽  
Data Collection ◽  
Energy Loss ◽  
Inelastic Scattering ◽  
Electron Spectrometer ◽  
X Ray ◽  
Electron Energy Loss Spectrometry ◽  
Data Collection And Analysis ◽  
Electron Spectrometry ◽  
Electron Energy Loss

Electron energy loss spectrometry (EELS) is the study of the inelastic scattering events which an electron undergoes during its passage through a sample. When an analysis of the elemental constituents of the specimen is required the most important inelastic events are the ionizations of inner shells of the atom since these cause discontinuities ("edges") in the EEL spectrum at energies which are charactertistic of the element concerned. A simple electron spectrometer combined with an electron microscope makes it possible to use this information for sensitive elemental identification and localization for all elements above Lithium. The EELS can thus be regarded as an adjunct to the more conventional energy dispersive X-ray spectrometer (EDS), which is restricted to elements above Magnesium. This paper discusses the necessary parameters of a EEL spectrometer designed for materials microanalysis, its coupling to the microscope and the basic techniques of data collection and analysis.

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.

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