Structure investigations of thin carbon foils

Dollinger, G.; Maier-Komor, P.; Mitwalsky, A.

doi:10.1016/0168-9002(91)90767-k

Cited by 25 publications

(11 citation statements)

References 11 publications

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“…These findings are supported by Díaz et al 52 who report that annealing of LPA foils at temperatures above 1100 K let the sp 3 content fall to zero. It is also interesting to note that recent HREM investigations 53 of thin carbon films made by laser-arc evaporation showed the same dense array of parallel curved graphene sheet segments packed in random orientations as the HREM pictures of Dollinger et al 44 which are representative for our LPA foils. They even show the same tendency to form onionlike graphene arrangements.…”

Section: The Graphite Targetssupporting

confidence: 74%

“…45 Foils which had been prepared under identical conditions have extensively been investigated by either high resolution electron microscopy ͑HREM͒ or electron diffraction ͑ED͒ with 80 keV electrons. 44 While for the LPA foil all low indexed rings of graphite can be observed and their intensity pattern indicates an isotropic distribution of crystallites, 41,44 the ͑002͒ ring is missing in case of the TE foil. Since diffraction angles are small for 80 keV electrons (⌰ 002 ϭ6.2 mrad͒ the lack of this ring implies that ͑002͒ planes cannot lie more or less perpendicular to the foil surface.…”

Section: The Graphite Targetsmentioning

confidence: 97%

“…The mounted foils were finally laser annealed: the TE foil at 4200 K for about 10 ns 44 and the LPA foil for 30 s at about 3000 K. 41 Transmission electron microscopy revealed a complete graphitezation of the foils and that the average length L a of the basal planes increased from less than 1 nm immediately after condensation to about 10 nm by this treatment. 44 ͑Interestingly, it was found by Dollinger et al 41 that heating LPA foils to 4200 K introduces anisotropies in LPA foils by preferential evaporation of oriented C clusters during annealing.͒ The evaporation time at the relevant vapor pressure (Ϸ10 Pa͒ of carbon is too low to result in noticeable ablation. Detailed elemental analysis by elastic recoil detection ͑ERD͒ showed that the major contamination is a hydrogen coverage of both surfaces of the foils which amounts to an overall content of a few atomic percent.…”

Section: The Graphite Targetsmentioning

confidence: 99%

“…The extent of anisotropy was estimated from the azimuthal intensity distribution of the ͑002͒ rings and yielded a deviation of the c axis from the foil normal with Ϯ7°full width at half maximum ͑FWHM͒. 44 Although the (h k 0) and (0 0 l)-rings of both the LPA and TE foils are identical to those of graphite, there are no (h k l) rings with h and l or k and l simultaneously nonzero. The same effect can be observed in special cases of bulk graphite ͑e.g., carbon black, 47,48 often also called ''turbostratic'' graphite 49,50 ͒.…”

Section: The Graphite Targetsmentioning

confidence: 99%

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Anisotropy of the electron momentum density of graphite studied by(γ,eγ)and(e,2e)spectroscopy

et al. 2001

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The electron momentum density ͑EMD͒ of two different modifications of graphite has been measured and the results of the measurements have been compared with theoretical calculations from three different theories: a full potential linear muffin-tin orbital, a modified augmented plane wave, and a pseudopotential calculation. Experimental results have been obtained by two different methods. The complete three-dimensional EMD is determined by inelastic photon-electron scattering, i.e., by the so-called (␥,e␥) experiment, and by electronelectron scattering, the (e,2e) experiment, cuts in the spectral electron momentum density are studied. For the (␥,e␥) experiment 180 keV synchrotron radiation from the PETRA storage ring at the Deutsches Elektronen-Synchrotron has been used with coincident detection of the recoil electrons. The (e,2e) experiments were carried out at the new (e,2e) spectrometer at the Australian National University using 40 keV primary electron energy and simultaneous detection of the outgoing electrons in an equal energy sharing mode. As samples we have prepared approximately 20 nm thin self-supporting graphite foils either by thermal evaporation ͑TE͒ or by laser plasma ablation ͑LPA͒. They are thin enough to suppress in essence electron multiple scattering. Electron diffraction analysis revealed that the LPA foil contains graphitic basal planes with a random distribution of c axes, whereas the TE foil was strongly c-axis oriented in the sense that the basal planes were parallel to the foil surface. In the analysis of the results special attention was devoted to anisotropies in the EMD revealed by comparison of TE and LPA foils. The (e,2e) measurements showed furthermore a strong orientation dependence of the intensity of and states ͑here we have for comparison additionally measured highly oriented pyrolytic graphite͒. The EMD's obtained by both techniques show anisotropies in the momentum distribution of graphite and are discussed in view of the theoretical results.

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Section: The Graphite Targetssupporting

confidence: 74%

Section: The Graphite Targetsmentioning

confidence: 97%

Section: The Graphite Targetsmentioning

confidence: 99%

Section: The Graphite Targetsmentioning

confidence: 99%

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Anisotropy of the electron momentum density of graphite studied by(γ,eγ)and(e,2e)spectroscopy

et al. 2001

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“…Thus, carbon foils should be best suited for this application. The highest possible homogenous density [13,14] combined to practically amorphous structure [15] is presented by foils prepared by laser plasma ablation. Laser plasma carbon foils not really have an amorphous structure but the randomly oriented nanocrystals consist only of a few atoms.…”

Section: Application Of Thick Carbon Stripper Foilsmentioning

confidence: 99%

Preparation and investigation of thick carbon foils prepared by laser plasma ablation deposition

Maier-Komor

Dollinger

Krücken

2006

Nuclear Instruments and Methods in Physics Research Section A:

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Self-Supporting Carbon Thin Films Used in the Heavy-Ion Beam

Thalheimer¹,

Hartmann²,

Klemm³

et al. 1999

Cryst. Res. Technol.

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Cryst. Res. Technol. 34 1999 2 175-179Self-supporting carbon thin films are needed for the heavy-ion beam at the Gesellschaft für Schwerionenforschung (GSI) as targets, as stripper foils, and as carrying substrates. The thin films are produced through resistance evaporation under high vacuum. Carbon is deposited on a glass plate that is covered with an organic material that is soluble in water. Through dissolving the interlayer a selfsupporting carbon film is obtained, which is fetched on an aluminium frame. Thin films of 5 µg/cm 2 up to 100 µg/cm 2 can be produced with this method. The production process as well as the changing of the layer structure through the energy deposit is going to be discussed.

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Structure investigations of thin carbon foils

Cited by 25 publications

References 11 publications

Anisotropy of the electron momentum density of graphite studied by(γ,eγ)and(e,2e)spectroscopy

Anisotropy of the electron momentum density of graphite studied by(γ,eγ)and(e,2e)spectroscopy

Preparation and investigation of thick carbon foils prepared by laser plasma ablation deposition

Self-Supporting Carbon Thin Films Used in the Heavy-Ion Beam

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