Collaborative Research: Modeling & Model Systems for Adsorbate Behavior in Lateral Confinement

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In this project, funded by the Macromolecular, Supramolecular and Nanochemistry Program of theChemistry Division, Prof. Theodore L. Einstein of University of Maryland and Prof. Ludwig Bartels ofthe University of California, Riverside, and their students will use a combination of scanning tunnelingmicroscopy and methods of statistical mechanics, especially Monte Carlo simulations and lattice-gasmodeling, to understand the formation of large regular self-organized networks of acene-relatedmolecules on substrates with prominent metallic surface states and the role of the resulting nanoscalepores in providing boundaries that modify the arrangements and reactions of small adsorbates like COtherein. With international collaborators we will test theories of modification (from large surfaces) keyreaction rates because of altered entropy of mixing in the confined pores and will study the relation of thesuperstructure to the surface state on the close-packed face of the copper substrate and investigate thecorrections to a simple picture of dot-induced pore formation. We will also take advantage of research intwo dimensional (2D) materials dominated by electronic states with many similarities to metallic surfacestates.This project will provide state of the art modeling and/or laboratory experiences for graduate andundergraduate students who will be learning the techniques of scanning probe microscopy andcomplementary Monte Carlo simulations and calculations of correlation functions, as well as ab initioelectronic structure calculations to help parameterize the statistical mechanical studies. The projectconsists of an exploration of the formation of regular porous superstructures by organic molecules onsubstrates with slowly decaying 2D electronic states. The validation of the novel explanation of porestabilization by 2D quantum-dot-like states will be pursued. The impact of such states on the distributionof small adsorbates (especially carbon monoxide) within the pore will be scrutinized. Calculations ofassociated parameters will require use of the latest advances in incorporating van der Waals interactionsinto density functional theory computations. Through leadership by a theorist experienced in statisticalphysics, this project will foster systematic perspective, deeper understanding and faster testing of resultsfor phase and pattern formation and predictions promising alternative substrates and adsorbates. Theproposed work is expected to have impact on industrial methodologies and society at large by providingaccess to large arrays of identical nanoscale cells in which one can do the experimental equivalent ofparallel computation. Control of such structures will allow tuning of cell sizes to select for favorableconfigurations and enhance particular reactions, as well as to explore natural fluctuations. The work willalso provide opportunities for educational and outreach activities with proven broad national,international and societal impact.