Surface excitation correction of the inelastic mean free path in selected conducting polymers

Gergely, György; Menyhárd, M.; Orosz, Tamás; Lesiak, B.; Kosinski, Andrzej S.; Jabłoński, A.; Nowakowski, Robert; Tóth, J.; Varga, D.

doi:10.1016/j.apsusc.2005.07.017

Cited by 9 publications

(19 citation statements)

References 24 publications

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“…Surface morphology, line scans and values of average surface roughness (between 5.59-19.93 nm) reported elsewhere [18,28] show negligible differences among the three polythiophenes. The PDOBT sample, however, seems to be different from the others having the largest surface roughness.…”

Section: Discussionmentioning

confidence: 99%

“…The surface excitation is described by the surface excitation parameter (SEP), P s (E, θ in , θ out ), that is defined by the number of surface plasmon excitations experienced by an electron with an energy E, impacting the surface at an incidence angle, θ in , and leaving the surface at an emission angle, θ out , with respect to the surface normal [15][16][17][18][19][20][21][22][23]. Then, the SEP consists of the incoming, P in , and the outgoing, P out , contributions…”

Section: Surface Excitationsmentioning

confidence: 99%

“…Values of a ch for selected elements have been proposed [23]. Otherwise, the material parameters by Werner et al [22], a H , and by Chen [23], a ch , for any multicomponent material can be estimated from the EPES [18,19,28] and reflection electron energy loss spectroscopy (REELS) methods [19]. For correcting the IMFPs due to surface excitation the measured intensity ratios are multiplied by the reciprocal of the surface excitation correction factor, f s :…”

Section: Surface Excitationsmentioning

confidence: 99%

“…Several methods have been proposed for the surface excitation correction [15][16][17][18][19][20][21][22][23]. The surface excitation is described by the surface excitation parameter (SEP), P s (E, θ in , θ out ), that is defined by the number of surface plasmon excitations experienced by an electron with an energy E, impacting the surface at an incidence angle, θ in , and leaving the surface at an emission angle, θ out , with respect to the surface normal [15][16][17][18][19][20][21][22][23].…”

Section: Surface Excitationsmentioning

confidence: 99%

“…The Monte Carlo (MC) algorithm used for simulating electron transport in a solid neglects recoil effect [11][12][13][14] and surface excitations [15][16][17][18][19][20][21][22][23]. The IMFPs for polythiophenes measured by EPES using a high resolution analyser have already been published [10].…”

Section: Introductionmentioning

confidence: 99%

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Influence of Recoil Effect and Surface Excitations on the Inelastic Mean Free Paths of Electrons in Polymers

et al. 2006

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In this work, the influence of recoil effect and surface excitations on the inelastic mean free paths for polythiophenes is investigated. The inelastic mean free paths of electrons in polythiophenes are measured with the elastic peak electron spectroscopy method using the Ag standard and the electron elastic scattering cross-sections from the database NIST 3.1 in the electron kinetic energy range 200-5000 eV. The Monte Carlo model is applied for evaluating the electron backscattering intensities from the polymers and the Ag standard, as well as for evaluating electrons quasi-elastically backscattered from atoms of different atomic numbers (the recoil effect). The surface excitation corrections are accounted for using the formalism of Chen, with the material parameters for polythiophenes evaluated from the elastic peak electron spectroscopy method. Deviations due to recoil effect and surface excitations to the inelastic mean free paths are compared and discussed. Correction to the inelastic mean free paths due to recoil effect is considerable but is smaller, however, than the correction due to surface excitations. Accounting for recoil effect and surface excitations leads to improvement of the inelastic mean free paths, as compared to the inelastic mean free paths resulting from the predictive formulae of Gries.

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Section: Discussionmentioning

confidence: 99%

Section: Surface Excitationsmentioning

confidence: 99%

Section: Surface Excitationsmentioning

confidence: 99%

Section: Surface Excitationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Influence of Recoil Effect and Surface Excitations on the Inelastic Mean Free Paths of Electrons in Polymers

et al. 2006

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Morphology, surface roughness, electron inelastic and quasielastic scattering in elastic peak electron spectroscopy of polymers

Lesiak

Kosinski

Nowakowski

et al. 2007

Surface & Interface Analysis

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In elastic peak electron spectroscopy (EPES), the nearest vicinity of elastic peak in the low kinetic energy region reflects electron inelastic and quasielastic processes. Incident electrons produce surface excitations, inducing surface plasmons, with the corresponding loss peaks separated by 1-20 eV energy from the elastic peak.In this work, X-ray photoelectron spectroscopy (XPS) and helium pycnometry are applied for determining surface atomic composition and bulk density, whereas atomic force microscopy (AFM) is applied for determining surface morphology and roughness. The component due to electron recoil on hydrogen atoms can be observed in EPES spectra for selected primary electron energies. Simulations of EPES predict a larger contribution of the hydrogen component than observed experimentally, where hydrogen deficiency is observed. Elastic peak intensity is influenced more strongly by surface morphology (roughness and porosity) than by surface excitations and quasielastic scattering of electrons by hydrogen atoms.

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Surface excitation parameter for selected polymers

Pauly¹,

Tougaard²

2008

Surface & Interface Analysis

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The surface excitation parameter (SEP) is theoretically determined for different polymers, namely, polyethylene (PE), polystyrene (PS), polyacetylene (PA) and polymethyl methacrylate (PMMA), for electron energies between 300 and 5000 eV and for angles between 0 and 70 o to the surface normal. We use our previous definition of SEP as the change in excitation probability of an electron caused by the presence of the surface in comparison with an electron moving in an infinite medium. The calculations are performed within the dielectric response theory by means of the QUEELS-ε(k, ω)-REELS software determining the energy-differential inelastic electron scattering cross-sections for reflection-electron-energy-loss spectroscopy (REELS). More precisely, the volume component for an infinite medium is subtracted from the calculated REELS cross-section and in this way the surface excitation component of the cross-section is determined and the SEP calculated. We find that the presence of an energy band gap reduces the SEP values compared to those for metals, and this decrease is larger for polymers with larger gaps.

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Surface excitation correction of the inelastic mean free path in selected conducting polymers

Cited by 9 publications

References 24 publications

Influence of Recoil Effect and Surface Excitations on the Inelastic Mean Free Paths of Electrons in Polymers

Influence of Recoil Effect and Surface Excitations on the Inelastic Mean Free Paths of Electrons in Polymers

Morphology, surface roughness, electron inelastic and quasielastic scattering in elastic peak electron spectroscopy of polymers

Surface excitation parameter for selected polymers

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