Soft X‐Ray Absorption in CuNi Alloys

Abstract

Cu-Ni alloy films have been investigated in the vicinity of the onset of 3p electron absorption in the photon energy range 50 to 90 eV. The spectra obtained can be described as a stoichiometric superposition of the individual Cu and Ni metal spectra. Any rearrangement of the states due to an alloy interaction is of no great influence. This result is in general agreement with results on soft X-ray emission, uv and X-ray photoelectric emission. It is in contradiction to the rigid band model and supports more recent alloy theories such as the coherent-potential approximation. This result, moreover, supports the interpretation of the wide structures in the transition metal spectra as a predominantly atomic effect.Dunne Schichten einer Cu-Ni-Legierung wurden in der Umgebung der Absorption der 3p-Elektronen im Photonenenergiebereich 50 bis 90 eV untersucht. Die Spektren konnen als stochiometrische Superposition der Spektren von Cu und Ni beschrieben werden. Veranderungen der ZustLnde durch die Legierungsbildung sind ohne merklichen EinfluB. Dieses Ergebnis zeigt die gleiche Tendenz wie Rontgenemissionsmessungen im weichen Rontgengebiet und Photoelektronenuntersuchungen im UV-und Rontgengebiet. Es steht im Widerspruch zum ,,rigid-band-model" und unterstiitzt neuere Theorien wie die ,,coherentpotential approximation". Dariiber hinaus spricht dieses Ergebnis fur eine atomare Deutung der breiten Maxima in den Spektren der ubergangsmetalle.

Photoabsorption Coefficient of Alloys of AI with Transition Metals V, Fe, Ni and with Cu and Pr from 30 to 150 eV Photon Energy

“…This need not always be the case, see e.g., Cu-Ni [23]: The L-absorption of A1 is changed more than the M-absorption of the transition metals or Cu. A complete understanding of the spectra we have measured is clearly not possible at this time.…”

Influence of alloying on the electron momentum density in the Cu-Ni system

“…At p z ϭ0 it amounts to about 2% of the total coincident profile, i.e., it is a rather small effect. These findings are supported by x-ray photoemission 57 and x-ray absorption spectroscopy, 54 which show that the density of states of Cu-Ni alloys can, to a very good approximation, be made up by superimposing those of Ni and Cu. This means that there is indeed only a very limited sharing of electrons by the two constituents.…”

“…Especially the use of ultrathin target foils opens the possibility to study a large class of random binary alloys that are produced far from thermodynamic equilibrium. Instead of producing the alloy by interdiffusion, they could be made either by simultaneous evaporation and condensation 54 of the constituents or by cosputtering. In this way arbitrary alloy compositions are achieved that would otherwise be impossible to get from the melt.…”

Optical properties and electronic structures of d- and f-electron metals and alloys, Ag-In, Ni-Cu, AuGa2, PtGa2, [beta]'-NiAl, [beta]'-CoAl, CeSn3, and LaSn3

“…Then the j-electrons near Ep come from only ATt-sites. This charge neutrality of the Ni-Cu system was also indicated by the soft-x-ray-emission[90] and -absorption measurements[80] [91]. Therefore, as the Ni concentration decreases, the density of states of the minority j-bands decreases…”