| Reaction and growth of ultrathin Ni and Pd films, deposited on Al(110) and Al(001) surfaces at room temperature were studied using high-energy ion scattering, x-ray photoelectron spectroscopy, and x-ray photoelectron diffraction. For Ni deposited on Al(110) surfaces, a strong Ni-Al reaction occurs at the Ni-Al interface. For the first two monolayers (ML) of deposited Ni, a NiAl-like compound is formed. The reaction continues with a different rate, forming a {dollar}rm Nisb3Al{dollar}-like compound for Ni coverages from 2 to 8 ML, at which point a Ni metal film begins to grow on the interface. However, Ni atoms deposited at {dollar}250spcircrm C{dollar} on the Al(110) surface, exhibit no surface compound formation, but diffuse 400 A deep into the Al bulk.; Interatomic potentials based on the embedded atom method are used in a Monte Carlo approach to simulate the evolution of the Ni-Al(110) interface as a function of Ni coverage. The calculated ion scattering yields and x-ray photoelectron intensities from Ni and Al atoms in these simulated interfaces are in good quantitative agreement with the experimental results. The ion scattering simulations show that a large amount of near-surface dechanneling occurs just below the Ni-Al(110) interface.; In contrast to the Al(110) room temperature results, Ni deposited on the Al(001) surface under the same experimental conditions results in the growth of metastable body-centered-cubic Ni at the interface up to 5 ML of Ni coverage in a Stranski-Krastanov growth fashion. After the bcc islands coalesce to cover the surface, a disordered Ni metal film covers the interface.; Ultrathin Pd films deposited on Al(001) surfaces exhibit strong reaction at the Pd-Al(001) interface. For the first 5 ML of deposited Pd, a PdAl-like compound is formed. After 5 ML of Pd coverage, a Pd metal film covers the reacted interface. |
