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