Secondary ion and Auger electron emissions from Ar+-ion-sputtered FeAl alloys |
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Authors: | J-F Hennequin R-L Inglebert PViaris de Lesegno |
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Institution: | CNRS, Laboratoire PMTM, Université Paris-Nord, Avenue Jean-Baptiste Clément, F-93430 Villetaneuse, France |
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Abstract: | Some FeAl alloys, and pure Al and Fe samples, are sputtered in ultrahigh vacuum with Ar+ ions between 4 and 15 keV. As previously observed with CuAl alloys, the intensity of the principal Al Auger peak at 63.5 eV is a parabolic function of the Al concentration. Symmetric collisions Al → Al are thus much more efficient for Auger emission from pure aluminium than asymmetric collisions Ar → Al, the proportion of which among effective collisions hardly reaches 20% at 15 keV. Whatever the initial ion energy, the intensities of singly charged atomic secondary ions Al+ and Fe+, normalized to pure metals, are equal to the atomic concentration of the corresponding elements, whereas the normalized intensities of the multiply charged ions Al2+ and Al3+ are roughly equal to the square of Al concentration. These results agree with the occurence of two mechanisms in intrinsic ion emission: an electronic excitation process during the separation of the outgoing particle from the target (singly charged ions) and a collisional process from the symmetric collisions Al → Al only, with multiple Auger de-excitation outside the target (multicharged ions of light elements). |
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