Ferroelectric Nanolithography Extended to Flexible Substrates Dawn A. Bonnell, University of Pennsylvania, DMR Recent advances in materials synthesis have yielded an ever increasing array of functional components from which to assemble devices. The ultimate goal is to assemble multiple components of diverse materials types into complex configurations. Ferroelectric Nanolithography achieves this by controlling local electronic structure on substrates that influences electron transfer at the surface. Previously this has been accomplished on rigid oxide substrates. Researchers at the Nanoscale Science and Engineering Center (NSEC) at the University of Pennsylvania demonstrated this on a ferroelectric polymer. Optical excitation of defect states in the band gap of PVDF provide electrons that interact at the surface of ferroelectric domains to produce patterned nanoparticles. Functional molecules can be attached to nanoparticles to produce nano-sized opto electronic devices Rankin, et al ACS Nano 2008

Local Dielectric Constants of Molecular Layers Dawn A. Bonnell, University of Pennsylvania, DMR The idealized system of an atomically flat metallic surface (HOPG) and an organic monolayer composed of porphyrin, is used to demonstrate how the dielectric function and associated properties of thin films can be accessed with a scanning probe technique. The junction of a metallic tip and surface is illiminated with a laser and the light scattering in the near field is detected. The theoretical analysis and numerical modeling, as well as experimental data, demonstrate that higher harmonic scattering can be used to extract the dielectric properties of materials with tens of nms spatial resolution. The 3d harmonic provides the best lateral resolution (~ 50 nm) and dielectric constant contrast for porphyrin molecules film HOPG, and the intensity of scattered s-polarized light is 100 times higher than that of p- polarized light for this configuration. hν

Local Dielectric Constants of Molecular Layers Dawn A. Bonnell, University of Pennsylvania, DMR The idealized system of an atomically flat metallic surface (HOPG) and an organic monolayer composed of porphyrin, is used to demonstrate how the dielectric function and associated properties of thin films can be accessed with a scanning probe technique. The junction of a metallic tip and surface is illuminated with a laser and the light scattering in the near field is detected. The theoretical analysis and numerical modeling, as well as experimental data, demonstrate that higher harmonic scattering can be used to extract the dielectric properties of materials with tens of nms spatial resolution. The 3d harmonic provides the best lateral resolution (~ 50 nm) and dielectric constant contrast for porphyrin molecules film HOPG, and the intensity of scattered s-polarized light is 100 times higher than that of p- polarized light for this configuration. hν

The interaction of micelles and vesicles with surfaces Dawn A. Bonnell, University of Pennsylvania, DMR Using the lessons learned from biological systems is an exciting approach to controlling nanostructures. To implement this strategy in practical applications, the interactions of biomolecules with surfaces must be understood. Micelles, vesicles, bilayers and biological membranes form through self-assembly of amphiphilic molecules such as detergents or lipids. The morphology and properties of self-assembled aggregates will be controlled by interaction with a solid substrate. Atomically smooth graphite is used as an ideal surface on which to explore these interactions. Micelles on a surface arrange to reduce the contact between hydrophobic graphite and water. Under the right conditions a hemicylindrical stripe pattern is developed, as shown on the upper right. Vesicles usually form as a bilayer sheet. However, under some conditions, a monolayer of lipids lying head-to-head in ordered rows forms. This is seen on the right. Vesicles adsorbed on graphite Micelles adsorbed on graphite 25 nm

The effect of metalloproteins on the structure of micelles adsorbed on surfaces Dawn A. Bonnell, University of Pennsylvania, DMR Synthetic peptides have been developed to template optically active molecules. These can be incorporated into micelles to enable nanostructure formation. It is important to understand how the insertion of a molecule such as a metalloprotein influences micelle aggregation. These experiments examine how the inclusion of a protein complex affects the way in which these structures form on a surface. PRIME was successfully incorporated into micelles in bulk solution, but consequences to behavior on surfaces was previously unknown. Hemicylindrical stripes form with the addition of PRIME. The pitch of the stripes in the case of pure micelles is 5.1 nm. With the addition of PRIME, the pitch increases to 5.5 nm. This change in pitch may be an indication that PRIME has remained incorporated in the aggregates during assembly on the surface. 25 nm Micelles adsorbed on graphite Micelles + PRIME adsorbed on graphite PRIME

Determining the electrical properties soft interfaces Dawn A. Bonnell, University of Pennsylvania, DMR The goal of this research is to measure the properties of oriented peptide-based assemblies on an idealized interface with new techniques in SPM for measuring properties. Topographic AFM yields some information about structure, but truly understanding this complicated system requires advanced techniques. A technique has been developed, nanoimpedance microscopy (TR-NIM), and it is capable of detecting small differences in resistivity and current. This technique allows one to implement nanoimpedance microscopy on soft surfaces such as those in lipid or micelle systems. The images on the right are TR-NIM of micelles on graphite. Top: topography of micelles on graphite. Right: current map