engleski

D-band quantum well states in Ag(111) monolayer films ; substrate-induced shifts

We report a study of 4d electronic states in monolayer silver films grown on Pd(111), Ni(111), Mo(110) and Cu(100) surfaces studied by means of high resolution angle-resolved photoemission spectroscopy (ARPES). The Ag-4d states, when measured in the surface Brillouin zone (SBZ) centre, show substrate dependent shifts. Density functional theory (DFT) calculations of free-standing silver monolayer provide evidence that the observed shifts are not induced by lateral expansion, compression or distortion of the silver unit cell. Using the phase accumulation model we show that 4d-derived electronic states in silver monolayers can be described in terms of quantum well states and that the matching of the electron wave functions at the interface with the substrate is one of the important mechanisms that generates the Ag-4d energy shifts. The dispersion of the states around SBZ centre is measured and discussed.

Quantum well states; Quantum effects; Ultra-thin films; Electronic properties

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