Analysis of reflection electron energy loss spectra (REELS) for determination of the dielectric function of solids: Fe, Co, Ni

Werner, Wolfgang

doi:10.1016/j.susc.2007.03.001

Cited by 29 publications

(14 citation statements)

References 43 publications

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“…Deviations from Palik's data were also reported by Werner. 28 In Ref. 21 it was found that the Yubero-Tougaard theory gives a good agreement with experimental effective cross sections determined by the Tougaard-Chorkendorff algorithm for a very wide range of geometries (35 -74 off normal), and energies 200, 500, and 1000 eV for several materials (Cu, Ag, Au, and Fe) all obtained with the same e(k,x) for each material.…”

Section: Introductionmentioning

confidence: 68%

Electronic and optical properties of selected polymers studied by reflection electron energy loss spectroscopy

Tahir¹,

Tougaard²

2012

Journal of Applied Physics

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We have determined the electronic and optical properties of six polymers: Polymethylmethacrylate (PMMA), polyethylene (PE), polyvinyl chloride (PVC), polyester (PET), polypyrrole (PPY), and polyamide (PA6) for energy losses from 0 to 70 eV by analysis of reflection electron energy-loss spectroscopy (REELS) spectra. We found that the surface was easily damaged by the incident electron beam, in particular for energies above 500 eV. The damage results in new peaks in the bandgap region and the polymers become metallic. Great care was exerted to determine experimental conditions under which these effects are minimized. The REELS spectra were corrected for multiple inelastically scattered electrons with the QUASES-XS-REELS software to determine the effective inelastic-scattering cross sections. From these cross sections, we found that the band gaps for PMMA, PE, PVC, PET, PPY, and PA6 are 5.0 eV, 7.5 eV, 7.0 eV, 3.0 eV, 3.5 eV, and 5.1 eV, respectively. Quantitative analysis of the experimental cross sections was carried out by using the QUEELS-e(k,x)-REELS software to determine the dielectric function and optical properties. This is done by comparing the experimental REELS inelastic electron-scattering cross-section with a simulated cross section in which the only input is Im(À1=e). The dielectric function is expressed as a sum of oscillators and the oscillator parameters are determined. Good agreement between the experimental and theoretical cross section is achieved for all polymers. From Im(À1=e), the real and imaginary parts of e (x), the refractive index, and the extinction coefficient were determined for all polymers in the energy range hx ¼ 0 to 70 eV. An oscillator is clearly observed for PPY, PET, and PA6 at $ 6.7 eV, which corresponds to the p plasmon. This oscillator is not found for PMMA, PE, and PVC. A set of oscillators in the 20-30 eV energy range corresponding to the rþp plasmon is found for all polymers. V C 2012 American Institute of Physics.

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Section: Introductionmentioning

confidence: 68%

Electronic and optical properties of selected polymers studied by reflection electron energy loss spectroscopy

Tahir¹,

Tougaard²

2012

Journal of Applied Physics

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“…The accuracy with which these quantities are known determines the reliability of the procedure for restoration of the differential inelas tic scattering cross sections from experiments deter mining the characteristic electron energy losses [17,18].…”

Section: Discussion and Approbation Of The Obtained Resultsmentioning

confidence: 99%

Theory of the formation of the energy spectra of reflected charged particles

Afanas'ev

Kaplya

2015

J. Synch. Investig.

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The theory of the formation of the energy spectra of electrons and light ions reflected form a solid surface is constructed. It is shown that methods based on the numerical solution of boundary value problems for the transport equation are the most effective. The boundary value problem is solved based on the invariant embedding method. Equations for the reflection coefficients describing the flux of atomic parti cles reflected in the direction n and having experienced k events of elastic scattering are obtained. The obtained results are compared with experimental data, the results of simulation using the Monte Carlo method, and the calculations of other authors.

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“…Firstly, the Monte Carlo (MC) simulation, that incorporates all physical phenomena governing the random path of the electrons and allows to reproduce the full REELS spectra, is a convenient way of comparison . Secondly, comparison between cross sections obtained from theoretical calculation and from REELS experiment is also a straightforward way to validate theories. From these two methods, excellent results have been achieved by different groups for various studied materials (see other works, for instance).…”

Section: Introductionmentioning

confidence: 89%

Energy dependence of the energy loss function parametrization of indium in the Drude–Lindhard model

Pauly

Dubus

Monier

et al. 2014

Surface & Interface Analysis

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The energy loss function (ELF) is a key parameter for the calculations of energy losses undergone by electrons in matter. It is often the only input in the calculations performed within the models based on the semi-classical dielectric response theory. Its perfect knowledge is thus of primordial importance. To evaluate the ELF, it is usual to consider as a model an expansion in Drude-Lindhard (DL) type oscillators with fixed values of the strength, width, energy and dispersion for the various oscillators. However, for materials that are characterized by a single sharp oscillator as aluminium or indium, it has been shown [Phys. Rev. B 46 (1992) 2486] that the damping parameter that corresponds in the DL model to the width of the oscillator increases for decreasing incident electron energy. To emphasize this effect, we perform in this work systematic calculation of the ELF for an indium target and for incident electron energies between 200 and 2000 eV. The ELF is determined by comparing REELS (reflection electron energy loss spectroscopy) experimental inelastic electron scattering cross sections with cross sections calculated within the semi-classical dielectric response model, which is implemented in the QUEELS-ε(k,ω)-REELS software (Quantitative analysis of Electron Energy Losses at Surfaces) [Surf. Interface Anal. 36 (2004) 824]. We also perform measurements and calculations for varying incident and exit angles of the electron, namely for angles to the surface normal between 15 o and 75 o , to check the validity of our results for all geometries. Our results show that the damping parameter of indium in the DL model for electron energy of 200 eV is three times larger than for energy of 2000 eV.

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Analysis of reflection electron energy loss spectra (REELS) for determination of the dielectric function of solids: Fe, Co, Ni

Cited by 29 publications

References 43 publications

Electronic and optical properties of selected polymers studied by reflection electron energy loss spectroscopy

Electronic and optical properties of selected polymers studied by reflection electron energy loss spectroscopy

Theory of the formation of the energy spectra of reflected charged particles

Energy dependence of the energy loss function parametrization of indium in the Drude–Lindhard model

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