CINT Nanoscience Integration Grand Challenges

Achieving the vision of nanoscience integration requires major advances in a number of nanoscience’s most challenging areas, including: 1) invention of bottom up assembly methods that can be integrated with top down fabrication; 2) understanding of interfaces and energy transfer between nanoscale objects to control properties of nanosystems; and 3) determination of design principles by which collective properties of nanosystems result from the assembly of nanoscale objects.  Success in these areas will enable tailoring the behavior of nanosystems. All three of these challenges figure prominently in our plan for CINT science.  The second and third areas define our current Nanoscience Integration Grand Challenges while the first area is included within both these Grand Challenges. 

Our Grand Challenges for nanoscience integration will exploit the strengths of CINT, cutting across all the thrusts to create a center of excellence for the key issues of integration.  These Grand Challenges have been identified through discussions and strategic planning by CINT scientists, discussions with the user community, and ongoing dialogue with CINT’s Science Advisory Committee. They are being focused and refined through the research of CINT scientists User projects. Special workshops, such as the Workshop on Energy Transfer: from the Nanoscale to the Macroscale, co-hosted by CINT and the International Institute on Complex Adaptive Matter on Mar. 12-13, 2007 further evolve these areas.

Energy Transfer – Exploiting the properties of materials that emerge at the nanoscale in functioning systems depends critically on the ability to transfer different forms of energy between nanoscale objects.  Nanoscale structures can interact strongly with various forms of energy (electronic, photonic, magnetic, etc.), and these interactions can provide new ways to control the collection, emission, transduction, and transfer of energy in various forms (excitons, plasmons, polaritons, etc.). Understanding the principles of energy transfer between nanoscale structures remains one of the grand challenges of nanoscience and is essential to achieving integration. Critical questions include:

• How can we understand and control energy transfer processes at the nanoscale?
• What are the fundamental limits and enabling principles for the integration of nanoscale heterostructures into systems that detect, transfer, and transduce energy with extreme sensitivity and efficiency?
• How can we design interfaces between soft and hard materials that allow one to achieve the great functionality and efficiency of nature’s designed systems while retaining the robustness of synthetic systems?

Answering these questions will provide a foundation for the application of nanotechnology in many areas, such as the sensitive detection of radiation and the high efficiency conversion of solar energy into electrical or chemical energy.

Efforts to understand and control energy transfer will cut across all the thrusts as described in the individual thrust proposals. Examples include designing new composite nanomaterials to allow the transfer of plasmons without loss in the Nanophotonics and Optical Nanomaterials thrust, the highly efficient separation and transport of electrons and holes in core-shell nanowires in the Nanoscale Electronics, Mechanics, and Systems thrust, the energy driven assembly in the Soft, Biological and Composite Nanomaterials thrust and the description of these processes at the quantum and molecular level in the Theory and Simulation of Nanoscale Phenomena thrust.
           
Emergent Properties – The concept of emergence is simply that the properties of a composite material cannot be predicted or understood in terms of the properties of the constituents comprising the material. This is often stated as the “whole is more than the sum of the parts.”  Emergence is a unifying theme across disciplines ranging from biology to condensed matter physics to nanotechnology. Examples of emergent behavior abound including, as examples, biological function of membranes, simple ferromagnetism, or intrinsic electronic inhomogeneities in correlated electron materials.

Emergence is particularly important in the context of nanoscience integration. Nanoscale architectures may be integrated to produce material systems where the coupling between structures can lead to new behavior. Understanding the principles underlying the collective behavior or emergent properties of composite nanoscale systems will open the door to the design of new nanoscale systems with desired performance.  In general, the collective properties of these systems cannot be anticipated from the properties of the individual constituents, making this one of the great challenges of nanoscience integration. Developing a fundamental understanding of the principles underlying the emergent behavior of composite nanoscale systems remains a daunting task, but success in exploiting such behavior in the integration of nanoscale structures offers the possibility of designing and fabricating new nanoscale systems with unprecedented performance.

Our challenge is to develop sufficient understanding to be able to design and assemble nanomaterials with a desired set of emergent properties and resultant functionality. Examples of areas of nanosystems functionality we seek to control include: energy collection, storage, and conversion; electronic and optical transport; electromagnetic response; magnetic properties; mechanical response; chemical response; ability to engage in self-assembly, self-healing, and self-replication; and molecular functionality (recognition, adhesion, transduction, specific catalysis, etc.). Critical questions include:

• How can we understand and control the collective response of composite nanoscale systems?
• How can we selectively tune competing interactions at the nanoscale to achieve specific emergent properties?
• How can we integrate bottom-up assembly with top-down fabrication to achieve bio-inspired assembly and hybrid nanostructures (including coupling bio, soft and hard materials) that exhibit some of the sorts of emergent behavior found in biological systems?