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Electronic sputtering of LiF, CaF 2 , LaF 3 and UF 4 with 197 MeV Au ions. Is the stoichiometry of atom emission preserved?

Toulemonde, M. and Assmann, W. and Muller, D. and Trautmann, C. (2017):
Electronic sputtering of LiF, CaF 2 , LaF 3 and UF 4 with 197 MeV Au ions. Is the stoichiometry of atom emission preserved?
In: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, Elsevier Science Publishing, pp. 501-506, 406, ISSN 0168583X, DOI: 10.1016/j.nimb.2016.11.034, [Online-Edition: https://doi.org/10.1016/j.nimb.2016.11.034],
[Article]

Abstract

Sputtering experiments with swift heavy ions in the electronic energy loss regime were performed by using the catcher technique in combination with elastic recoil detection analysis. Four different fluoride targets, LiF, CaF2, LaF3 and UF4 were irradiated in the electronic energy loss regime using 197 MeV Au ions. The angular distribution of particles sputtered from the surface of freshly cleaved LiF and CaF2 single crystals is composed of a broad cosine distribution superimposed by a jet-like peak that appears perpendicular to the surface independent of the angle of beam incidence. For LiF, the particle emission in the entire angular distribution (jet plus broad cosine component) is stoichiometric, whereas for CaF2 the ratio of the sputtered F to Ca particles is at large angles by a factor of two smaller than the stoichiometry of the crystal. For single crystalline LaF3 no jet component is observed and the angular distribution is non-stoichiometric with the number of sputtered F particles being slightly larger than the number of sputtered La particles. In the case of UF4, the target was polycrystalline and had a much rougher surface compared to cleaved crystals. This destroys the appearance of a possible jet component leading to a broad angular distribution. The ratio of sputtered U atoms compared to F atoms is in the order of 1–2, i.e. the number of collected particles on the catcher is also non-stoichiometric. Such unlike behavior of particles sputtered from different fluoride crystals creates new questions.

Item Type: Article
Erschienen: 2017
Creators: Toulemonde, M. and Assmann, W. and Muller, D. and Trautmann, C.
Title: Electronic sputtering of LiF, CaF 2 , LaF 3 and UF 4 with 197 MeV Au ions. Is the stoichiometry of atom emission preserved?
Language: English
Abstract:

Sputtering experiments with swift heavy ions in the electronic energy loss regime were performed by using the catcher technique in combination with elastic recoil detection analysis. Four different fluoride targets, LiF, CaF2, LaF3 and UF4 were irradiated in the electronic energy loss regime using 197 MeV Au ions. The angular distribution of particles sputtered from the surface of freshly cleaved LiF and CaF2 single crystals is composed of a broad cosine distribution superimposed by a jet-like peak that appears perpendicular to the surface independent of the angle of beam incidence. For LiF, the particle emission in the entire angular distribution (jet plus broad cosine component) is stoichiometric, whereas for CaF2 the ratio of the sputtered F to Ca particles is at large angles by a factor of two smaller than the stoichiometry of the crystal. For single crystalline LaF3 no jet component is observed and the angular distribution is non-stoichiometric with the number of sputtered F particles being slightly larger than the number of sputtered La particles. In the case of UF4, the target was polycrystalline and had a much rougher surface compared to cleaved crystals. This destroys the appearance of a possible jet component leading to a broad angular distribution. The ratio of sputtered U atoms compared to F atoms is in the order of 1–2, i.e. the number of collected particles on the catcher is also non-stoichiometric. Such unlike behavior of particles sputtered from different fluoride crystals creates new questions.

Journal or Publication Title: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms
Volume: 406
Publisher: Elsevier Science Publishing
Uncontrolled Keywords: Sputtering, Swift heavy Ions, LiF, CaF2, LaF3, UF4
Divisions: 11 Department of Materials and Earth Sciences > Material Science > Ion-Beam-Modified Materials
11 Department of Materials and Earth Sciences > Material Science
11 Department of Materials and Earth Sciences
Date Deposited: 29 Dec 2017 12:04
DOI: 10.1016/j.nimb.2016.11.034
Official URL: https://doi.org/10.1016/j.nimb.2016.11.034
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