Structure and dynamics of Na adsorption on Al(100)

• The adsorption of 0.2 monolayers (ML) of Na on Al(100) has been studied both experimentally, using low energy electron diffraction (LEED) and high resolution core level spectroscopy (HRCLS), and theoretically, using density functional theory (DFT). Two ordered phases are found: Islands of c (2×2) symmetry with Na atoms occupying four-fold hollow sites result from low temperature deposition and a (√5×√5)R27° structure with Na in surface substitutional sites is formed by annealing of the low temperature island structure at 300 K and subsequent cooling below 230 K. The (√5×√5)R27° structure undergoes a reversible order-disorder phase transition at ~230 K. To investigate this phase transition further, we performed additional DFT calculations for a wide range of coverages (from 0.0625 to 0.5 ML), for adsorption in both hollow and substitutional sites, from which we extract interaction energies which are used in a lattice gas Monte Carlo simulations

Ämnesord

NATURVETENSKAP  -- Fysik -- Den kondenserade materiens fysik (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences -- Condensed Matter Physics (hsv//eng)

NATURVETENSKAP  -- Fysik -- Atom- och molekylfysik och optik (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences -- Atom and Molecular Physics and Optics (hsv//eng)

Nyckelord

Al(100) substrate

Na adsorption dynamics

monolayers

density functional theory

four fold hollow sites

low temperature deposition

substrate substitutional sites

annealing

island structure

cooling

Monte Carlo simulations

order-disorder phase transition

300 K

230 K

Al

Na

high resolution core level spectroscopy

LEED

low energy electron diffraction

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