Please post and forward to your group(s). Joint Seminar: Physical Chemistry and Center for Excitonics Navigating Space-Time with Ultrafast Exciton Photolithography or Scintillating Near-fields to Follow Dynamic Processes in Molecular Materials May 5, 2015 at 4:30pm/ rm: 4-370 Naomi Ginsberg University of California/Department of Chemistry and Physics [nsginsberg] abstract: A cross-cutting theme in my research group is to examine dynamic processes in spatially-heterogeneous condensed phase molecular materials over a wide range of time scales. I will share recent results in multiple areas, all underpinned by the strong correlation between physical structure and the optical properties of materials. Our investigations often require tailoring the spatial and temporal resolution of our measurement approaches. I will explain how by measuring the ultrafast electronic properties of heterogeneous, ‘printed’ semiconducting films of small organic molecules we infer the much slower dynamics by which complex nanoscale structural motifs in the films emerge when they self-assemble in an evaporating solvent. These studies reveal the generation of non-equilibrium nanoscale structures that arise from coupling the dynamics of fundamental phase transformation processes of solute crystallization with solvent evaporation. They also pinpoint the challenges associated with developing high carrier mobility materials for printed plastic electronics. The migration of Frenkel excitons, tightly-bound electron-hole pairs, in organic and hybrid organic-inorganic semiconducting films is critical to the function of many next generation optoelectronic devices. While these materials can exhibit a high degree of structural heterogeneity on the nanoscale, traditional measurements of exciton diffusion lengths are performed on bulk samples. Since both the characteristic length scales of structural heterogeneity and the reported bulk diffusion lengths are typically smaller than the optical diffraction limit, I will describe how we adapt far-field super-resolution fluorescence imaging to determine in-situ exciton diffusivities and to uncover the correlations between the structural and energetic landscapes that the excitons explore. Motivated by the need to observe the dynamics of biomolecular interactions on their characteristic length scales, I will also show how we have appropriated the nanoscale resolution of electron microscopy and the near-field luminescence properties of scintillating oxide films to non-invasively image soft materials that cannot be interrogated directly with a damaging electron beam. In addition to focusing on soft materials in organic electronics and biology, I will also demonstrate this new imaging modality applied to plasmonic nanostructures. bio: Naomi Ginsberg received a B. A. Sc. from the University of Toronto (Engineering Science) (2000) and a Ph.D. from Harvard University with the Physics – Hau group (2007). From 2007 – 2010, she was a Postdoctoral Fellow in the Physical Biosciences Division-Fleming group at the Lawrence Berkeley National Laboratory. Awards include UC Berkeley Department of Chemistry Teaching Award (2013), DARPA Young Faculty Awardee (2012), Packard Fellow for Science and Engineering (2011), and Cupola Era Endowed Chair in the College of Chemistry (2010-2012). Her group focuses on visualizing ultrafast energy flow in natural and artificial light harvesting systems and on combining electron and optical microscopies to facilitate high-resolution studies of living things and molecular interactions in solution. Naomi’s background in chemistry, physics, and engineering has led her to observe coherent and previously obscured energy transfer in light harvesting complexes from plants, to develop polarization techniques in ultrafast multidimensional spectroscopy to extract structure from electronically-coupled systems, to slow, stop, and store light pulses in some of the coldest atom clouds on Earth, and to discover, follow, and understand the interactions of superfluid nonlinear excitations.