J. Tóth

Recoil effect in carbon structures and polymers

Abstract The recoil effect on quasi-elastic scattering of electrons has been described by Boersch. The Rutherford type scattering on the nucleus produces a shift of the elastic peak maximum of Δ E em , proportional to 1/ M (atomic mass) and electron energy. Laser et al. studied the recoil effect for exact calibration of the energy scale for XPS. The other effect is broadening of the elastic peak. Reflection electron energy loss spectra were studied by an electron spectrometer ESA 31 of high energy resolution. Various modifications of C (electrode and reactor graphite, glassy C, powder) and conducting polymers (polyacetylene, polyaniline, polythiophene) have been studied with varying composition of C, O, H, S, Pd etc. In the case of the samples containing different elements the complex nature of the elastic peaks (consisting of the sum of components having different intensities and shifts) was clearly observed. Possible explanations for the recoil effects detected are reviewed.

Crystalline effects in elastic peak electron spectroscopy

Abstract Elastic peak electron spectroscopy (EPES) is confined to incoherent elastic scattering, appearing in the elastic peak intensity I e . Ion bombardment cleaning disorganizes the surface layer and might produce a component enrichment. EPES was used for the experimental determination of the inelastic mean free path of electrons on ion bombarded Si, GaAs, InP, InSb and GaSb crystals. Imperfect amorphization can produce diffraction or directional elastic peak electron spectroscopy (DEPES) effects influencing the elastic peak intensity. They appear in the Renninger plots of I e rotating the sample around its azimuthal axis. The problem was met with the inelastic mean free path studies on InSb and GaSb crystalline samples working with a hemispherical analyser. The surface composition after Ar bombardment was checked by in situ X-ray photoelectron spectroscopy and electron energy loss spectroscopy. Using 2xa0keV Ar + sputtering, the enrichment of In or Ga was avoided, whereas In metallic phase was formed by 10xa0keV ions. The energy values of diffraction on Si(1xa01xa01), and III–V (1xa00xa00) crystals was calculated for a cylindrical mirror analyser and for a hemispherical analyser. Incoherent elastic scattering occurs in the minima of Renninger plots. The goal is to avoid diffraction and DEPES effects. They are eliminated by Ar + ion bombardment. The thickness of the amorphized layer was controlled by the Ar + ion energy and dose.

Recoil broadening of the elastic peak in electron spectroscopy

Abstract Electrons scattered elastically by the atomic nuclei suffer Rutherford-type recoil losses. This results in the shift Δ E em and width broadening Δ E eR of the elastic peak. This paper deals with the recoil broadening Δ E eR and the shape of the elastic peak, varying considerably for low Z (atomic number) elements and compounds. For the high Z region we assume, that Δ E emAu and Δ E eRAu can be neglected. Gold was used as the reference in our work. The E p primary energy dependence (1–5xa0keV) of Δ E eR was studied by spectrometers of high-energy resolution ESA 31 and DESA 100 on elemental Au, Ag, Pd, Ge, Ni, Cu, Si, C (graphite and glassy carbon powder) and on LiF. The elastic peak in the latter case is split to those due to Li and F. Several processes, possibly contributing to the recoil broadening (multiple elastic scattering, Doppler broadening, low-energy losses, e.g. phonons) are considered. The effects of recoil on the shape of the elastic peaks confirm that the peak areas should be used in determining the elastic yield ratios which are important for derivation of the inelastic mean-free path in solids.

Laser direct writing of tin oxide patterns

Abstract Tin oxide pattern generation by laser deposition from SnCl 4 · 5H 2 O in isopropanol is reported. Smooth, even stripes of thicknesses ranging from 20 to 120 nm with sharp, well defined edges and cross-section are deposited by scanning Ar + laser beam (λ = 514.5 nm) focused onto the substrate—solution interface with a constant speed of 1 mm s −1 . The linewidth linearly increases from 26 to 42 μm with increasing the power from 40 to 120 mW. The reproducibility of pattern generation is extremely good as revealed by SEM-EDXI and μRBS. The minimum DC resistivity of 1.7×10 −2 Ωcm, measured without any process optimization, favourably compares with those reported for films prepared by other techniques. The chemical composition of the film material is SnO x with 1.1 x

Determination of the inelastic mean free paths of electrons by elastic peak electron spectroscopy in organic samples

Abstract The inelastic mean free path (IMFP) values for selected polymers were determined using elastic peak electron spectroscopy (EPES). Large scatter between measured and calculated IMFPs for polymers has been observed. In the present work the IMFPs in CH3- and OCH3-substituted polyanilines undoped and doped with Pd of various concentrations using the EPES method with a standard are investigated. This method requires knowledge of surface composition and density. Composition was determined by X-ray photoelectron spectroscopy (XPS) and bulk density by helium pycnometry. Bulk Pd concentration was evaluated by atomic absorption (AA). The EPES measurements using the Ag standard covering the energy range 200–5000 eV were made with the ESA-31 spectrometer. The influence of Pd dopant in polymers on measured IMFPs has been investigated. The scatter between measured and the G1 of Gries predicted IMFPs and its reason are discussed.

Resolution correction in EELS

Abstract Correction for inelastically scattered electrons is important in determining intensities in elastic peak electron spectroscopy (EPES), e.g. for obtaining information on inelastic mean free paths in the material, relevant parameters in quantitative applications of electron spectroscopy. The spectral shape of electron energy loss spectra depends more strongly on the spectrometer function in the elastic peak region, than in the continuous energy part. Therefore the resolution correction of the EELS spectra results in a considerable change of the spectral shape. The importance and the role of this correction is demonstrated in the case of REELS of Ni sample comparing the shapes of EELS spectra measured at different energy resolutions using different type spectrometers : (1) home-made HSA (ESA 31). Debrecen ; (2) home-made HSA (Clermont Ferrand) ; (3) CMA MAC2 by CAMECA-RIBER and a HSA (Lyon) ; (4) CMA OPC105 type by RIBER (Budapest).