Referenced to the submitted proposal, my work on this award was related to background sections 4.1.2, 4.1.3, and 4.1.5 on step energetics and dynamics, island nucleation and growth, and quantum size effects in growth of ultrathin metal films, respectively. Generically this is work on complex morphology and nanostructures at surfaces and interfaces.Regarding proposed work, my efforts were directed toward sections on kinetic Monte Carlo (KMC) and step dynamics, with some attention to continuum modeling, focused on islands and quantum dots on flat and stepped surfaces. In some cases, long-range interactions, both elastic and electronic, were involved. The relevant sections are 4.2.1.3-4 and 4.2.2.2.
Collaborations fostered by this CMSN award:Consistent with the goals of this program, this award led to several collaborations with other members of the team. Most notably, I interacted repeatedly with James W. Evans and his group at Iowa State on work to characterize capture zones (proximity cells) around growing islands. This led to their performing detailed simulations which uncovered shortcomings in our meanfield analysis, which led us to improve our analytic treatment of the problem. Specifically, this research eventually led to a comment by them and a reply by my group The essence of this work is that new islands due not nucleate randomly but rather form preferential near the borders between capture zones, where newly deposited atoms are least likely to diffuse quickly to a preexisting island.As a result of several discussions with Michael Tringides at Iowa State, he applied our capture zone analysis to his extensive data on islands (Pb on Si) with heights determined by quantum size effects. We are still working on analysis of his data.Over the years I have had many interactions with K.-M. Ho and C.-Z. Wang on a wide range of topics, including my belief that quantum islands extend down to the substrate rather than riding on the wetting layer that is known to permeate between the islands, an idea that they later confirmed with painstaking calculations.Over the years I have had broad and continued discussions with Zhenyu Zhang at U. of Tennessee and formerly at ORNL, most notably on quantum size effects (which after many iterations led to a Phys. Rev. Letter, cited below), but also on adsorption on graphene, electromigration, and other topics. I had arranged for a graduate student to spend some weeks at ORNL and currently my postdoc is being supported through U. of Tennessee. The PRL showed that Friedel oscillations on Pb(111) decay more slowly than for other metal surfaces, due to the unusual shape of lead's Fermi surface. The paper carefully characterizes the oscillatory behavior of electron density and displacements as a function of distance from the