Experimental evidence for a nonparabolic nanoscale interface shift during the dissolution of Ni into bulk Au(111)

Abstract

We report experimental evidence for the violation of the "diffusional parabolic law" ͑x ϰ t 0.5 , where x is the interface shift and t is time͒ as predicted recently by computer simulation ͓Z. Erdélyi et al., Phys. Rev. B 69, 113407 ͑2004͔͒ for a binary system with restricted mutual solubility. Using x-ray photoelectron spectroscopy we investigated the shift of the interface between a thin Ni layer ͑3 nm͒ deposited under UHV conditions on top of a Au͑111͒ single crystal during its thermally driven dissolution into the Au substrate. From the temporal evolution of the Ni-2p and Au-4f core level intensities at various fixed temperatures, a power law could be extracted for the time dependence of the interface shift ͑ϰt k c ͒ with exponents in the range of 0.6-0.7. Thus, clear experimental evidence is provided that the kinetics of such a shift might differ from the well known parabolic law if restricted to the nanometer scale.

Studying the bulk band structure of niobium by scanning tunneling spectroscopy

“…The Ni sample showed bright hexagonally arranged LEED spots and X-ray photoelectron spectroscopy revealed a clean Ni layer on gold. STM images of the Ni surface revealed atomically flat terraces of width several nanometer separated by monatomic steps [14].…”

Alloy formation in the Au{111}/Ni system – An investigation with scanning tunnelling microscopy and medium energy ion scattering

“…This finding was supported by Jones et al [12] who concluded that the density of Au is substantially higher in the ultrathin film than that of bulk Au. Katona et al [13] examined the deposition of Ni ($13 ML) on Au{1 1 1} and reported that upon thermal treatment at between 643 and 733 K, Au atoms preferentially segregated on top of the Ni film, followed by the dissolution of Ni atoms into the Au single crystal with further thermal treatment.…”

Kinetic critical radius in nucleation and growth processes – Trapping effect

“…For example at 800 K, m ′ 6.5 in Fe-Cr, m ′ 4.5 in Cu-Co systems (see also some other examples and interesting phenomena related to the large asymmetry in Ref. 19,20,21,22,23,24). Note, that according to the Arrhenius-type temperature dependence of the diffusion coefficient, m ′ increases with decreasing temperature due to the different activation energies in A and B.…”