CINT User Workshop
January 19-21, 2005  

The Discovery Platform breakout sessions (and invited speakers)

I. Energy Transport (Marcus, Harvard; Klimov, LANL)

Nonradiative energy transfer is an important communication and transport mechanism at the nanoscale. In contrast to coherent coupling that requires strong interactions via, e.g., electron exchange; incoherent energy transfer relies on long-range electrostatic Coulomb interactions that can potentially enable highly parallel, defect tolerant, and easily scalable communicating structures. As an alternative to traditional charge transport, Förster-type exciton transfer can provide an efficient energy transport mechanism in semiconductor nanostructures. On the other hand, strong electrostatic "plasmonic" interactions can be used for controlling energy flows in metal nanoassemblies. The ability to predictably control interfacial electrostatic interactions can lead to such important applications as electrically pumped tunable light emitters, on-chip plasmonic circuitry, artificial photosynthesis, low-cost photovoltaics, Terahertz detectors, and bio/chemical sensors.

This session will explore the range of scientific issues and discuss the feasibility of a “platform approach” in studies of electrostatic interactions as a mechanism for controllable coupling between individual building blocks in nanoscale assemblies, novel quantum coherent electronic states with potential applications to solid state quantum computing, as well as a mechanism for interfacing nanoscale systems with a “macro-world.” Suggested topics for discussion include but are not limited to:

• Platforms for real-time, real-space monitoring of energy flows in nano-assemblies
• On-chip excitonic generators/detectors
• Platforms for studies of energy-gradient excitonic nanostructures
• On-chip plasmonic generators, waveguides, and focusing structures
• Platforms for quantum coherent transport and pseudo-spin states in nanoelectronic structures
• Mechanically and electrically controlled plasmonic and excitonic circuits
• Platforms for studies of electrostatic interactions in hybrid excitonic-plasmonic nanostructures
• Exciton transport in photonic nanostructures

II. Synthesis and Assembly (Braun, UIUC ; Lu, Tulane)

Self-assembly methods offer great potential for building nanomaterial-based structures and devices. In order to move from current state of scientific discovery to a state where self-assembly can be used as a highly predictable and controllable manufacturing tool, better understanding of assembly process and methods are required. Of particular importance is understanding the role of external fields and interfaces on the self-assembly process. CINT’s technical vision for the integration of nano and micro lengthscales places significant importance on understanding the interplay between top-down, lithographic assembly techniques and the bottom-up self-assembly methods. Of key importance to understand how the geometric and chemical tailoring of micro/nano fabricated interfaces as well as the application of localized mechanical, optical, magnetic, and electrical fields can be used to control molecular and nanoscale self-assembly processes.

This session will explore the range of scientific issues and discuss the feasibility of a “platform approach” to control materials synthesis on multiple length scales and to integrate so-called bottom-up self-assembly and top-down lithography approaches. The ideal platforms will contain nano- and macroscale patterns obtained from the state-of-the art microfabrication techniques, and should be integrated with temperature and/or electronic control microdevices and appropriate in-situ analytical tools. By providing optical, electronic, magnetic and fluidic addressability, we hope to use external fields to direct assembly and to provide multiple means to characterize in situ nanomaterials structure and function. Suggested topics of discussion include:

• Length scale and the geometric confinement of the nano- and micropatterns to control the assembly and alignment of the nanomaterials.
• Use of micro- and nano-fluidic environments to control chemical synthesis of nanomaterials.
• Use micropatterned arrays and on-board stimuli to direct, control and program materials assembly and/or synthesis.
• Analytical tools on the platform to provide in-situ capabilities for characterizing the structures and the properties of the materials, including real-time spectroscopic monitoring.

III. Biology/Fluidics (Bonnell, U Penn; Meldrum, UW)

Analysis of the properties and functions of biological systems beginning with single molecules and progressing to the behavior of individual cells and small populations of cells in a rapid and high-throughput manner will provide new information that will contribute to reliable and predictive models for biological systems. As an example, individual cell based studies of responses to environment, signaling pathways, metabolic processes, cell proliferation, and host-pathogen interactions. Technologically, such studies require the development of integrated tools for single cell manipulation and ultra-sensitive detection of small numbers of target molecules. Similarly the examination of molecular-level function will benefit from new tools and platforms that enable manipulation of biomolecules within environments where optical, electrical, mechanical, etc. energy can be coupled into and out of molecules and small molecular assemblies.

This session will explore the range of scientific issues and discuss the feasibility of a “platform approach” to provide fluidic, mechanical, thermal, optical, etc. manipulation of individual molecules, cells and cellular contents, and the integration of fluidic systems to sensitive detection approaches will be the focus of this breakout session. Suggested topics of discussion include:

• Scientific motivation for single molecule through single-cell analysis
• Fluidic systems for cell manipulation, lysing and handling of cellular contents
• Use of biological recognition elements in platforms
• The role of surface modification in platform performance
• Integration of fluidic systems with transduction based on electronic or optical methods

IV. Nanomechanics (Nix, Stanford ; Clelland, UCSB)

The mechanical response of nanoscale materials and structures has important implications diverse areas of science spanning topics that include understanding of biological recognition, development of lightweight structural materials, to exploration of new concepts for switches and chemical sensors. While instruments, such as nanoindentation, exist to measure mechanical properties of nanostructured films on substrates, the development of techniques to reliably measure mechanical response of structures with nanometer-scale architectural dimensions such as nano-wires, nano-tubes, nano-dots, nano-films, nano-pillars, nano-porous, etc, remains a challenge in nanomechanics. In parallel there is need to elucidate the mechanisms of deformation in nanometer-scale structures via a combination of in situ electron microscopy and atomistic modeling. This session will explore the range of scientific issues and discuss the feasibility of a "platform approach" to elucidate mechanisms of elastic and plastic behavior for nanostructured materials, and to test new scientific concepts based on integrating nanomechanical structures together with other functional elements (electrical, optical, biological, chemical). It is envisioned that some measurement techniques may combine mechanical test with real time observation of deformation in a suitable microscope such as TEM or AFM. Suggested topics of discussion include:

• Differences in mechanical behavior of materials with nanometer-scale architectural dimensions from the same material in the bulk form.
• Influence of interfaces and boundary conditions on mechanical response of nanomaterials including nano-wires, nano-tubes, nano-dots, etc represent the building blocks of integrated nanoscale devices.

V. Electronics and Organic/Inorganic Materials (Reed, Yale; Basov, UCSD; Tanaka, Osaka)

Improving our understanding of the complex coupling between the electronic and structural degrees of freedom in organic molecules such as polymers, DNA, and other macromolecules requires a suite of complementary experimental probes including, for example, inelastic tunneling spectroscopy, and dynamic and time-integrated optical spectroscopies. In addition, the ability to easily manipulate organic materials to isolate, though detailed experimental study, intrinsic phenomena from phenomena arising due to intermolecular coupling or environmental interactions is highly desirable. This will facilitate an improved understanding of the potentially useful properties of organic materials and aid in designing hybrid organic/inorganic functional nanomaterials.

This session will explore issues on such electronic degrees of freedom with a view towards controlling the properties of these materials and the constraints such investigations imply for the design of platforms in this arena. The utility of general, user-friendly, platforms must address several important questions.

• Can platforms be designed which allow for the facile incorporation of a variety of different organic materials to meet user needs?
• What level of complexity will be required in the platform design to permit experiments in which the local environment can be modified during the experiment?
• Should the platforms focus primarily on single molecule experiments?
• What level of sensitivity is required and can this be balanced with multifunctional operation? Hopefully, these questions and others that arise during the breakout session will provide a roadmap for fabricating first-generation platforms of broad utility with a view towards improving our understanding of the coupled degrees of freedom in organic materials.