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| - Structural Models and Thermal Desorption Energetics for Multilayer Assemblies of then-Alkanes on Pt(111)
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| - The structural and thermodynamic properties of linear hydrocarbon multilayer assemblies supported on aPt(111) single-crystalline substrate are investigated with temperature-programmed desorption and infraredreflection absorption spectroscopies. The multilayer assemblies are comprised of all-trans chains preferentiallyaligned with their ccc planes parallel to that of the surface. Coverage-dependent vibrational spectra revealthat the deposition process, up to the first monolayer total coverage, proceeds first via an island growthmechanism. This result demonstrates that an important contribution is made by (chain-length-dependent)attractive lateral interactions to the binding energies of the monolayer films. The subsequent layers depositedin a multilayer appear to contain a modest concentration of conformational/orientational defects (and perhapslayer misplacements as well). The energetics of the desorption processes for these hydrocarbon assembliesare rationalized on the basis of a conserved value of a prototypical segmental heat of adsorption. The kineticmodel embodying this description involves a layer-by-layer desorption and invokes a central role for lateralinteractions and diffusion in maintaining the kinetic competence of a general mechanism of monolayerevaporation from two-dimensional island domains.
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