Nanotechnology Project

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Environment, Health and Safety Research

ADVANCE Fellow: Microscopy of Nanomaterials

Project Information

Principal InvestigatorValerie Leppert
InstitutionUniversity of California-Davis
Project URLView
Relevance to ImplicationsSubstantial
Class of NanomaterialGeneric
Impact SectorCross-cutting
Broad Research Categories Characterization
NNI identifier

Funding Information

Anticipated Total Funding$448,833.00
Annual Funding$89,766.60
Funding SourceNSF
Funding MechanismExtramural
Funding SectorGovernment
Start Year2002
Anticipated End Year2007


The purpose of the proposed research is to develop a new characterization technique for investigating the size-dependent magnetic, optical, and electronic behavior of nanomaterials. An understanding of the origin of these new properties is essential for their exploitation in a variety of technologies, including high-density magnetic recording, high-speed optical computing, solar energy, environmental toxicology, biomaterials, and biosensors. The technique that will be developed is electron energy-loss spectroscopy (EELS) in the transmission electron microscope (TEM). New developments in the energy-resolution of EELS (<0.3 eV) will be used in concert with the high spatial-resolution of TEM to correlate the electronic and optical properties of individual nanoparticles to their size, shape, composition, and surface morphology. Specific materials for initial investigation will be gallium nitride and silicon nanoparticles, synthesized by the PI and her collaborators. The electronic and optical properties of individual nanoparticles will be extracted from the low energy-loss and fine structure portions of the EELS spectrum. Results will be compared to information collected from X-ray absorption spectroscopy (XAS) and optical spectroscopy, as well as modeling efforts. This information will in turn be related to the physical morphology (size and shape) of the individual nanoparticles, particular surface reconstructions present (via phase-contrast microscopy), and elemental composition and distribution (e.g. doping, core/shell structures). The potential impact of this work on understanding the origins of size-dependent properties is expected to be enormous, given that the capability of the proposed technique is unique in permitting the study of individual nanoparticles, rather than ensembles of nanoparticles. Intense worldwide research over the last twenty years has been focused on understanding the effect on the magnetic, optical, and electronic properties of a bulk material when size is reduced to less than about 10 nanometers (less than one in a hundred millionths of a meter). Investigation of the behavior and origin of these size-dependent properties is critical for their full exploitation in a broad range of technologies: high-density magnetic recording, high-speed optical computing, solar energy, environmental toxicology (including chemical and biological weapons detection), biomaterials (for example, artificial organs), and biosensors for advanced medical testing. The small size scale of the materials under investigation demands that new techniques be developed for understanding their properties, since traditional characterization techniques typically study millions of particles at a time, rather than single particles alone. The goal of this project is to use new developments in electron microscopy to correlate the magnetic, optical and electronic behavior of individual nanoparticles to their specific size, shape, composition and surface structure. This will be achieved by taking full advantage of the ability of electron microscopy to image features less than 0.2 nm in size, as well as new developments in spectroscopic methods in the electron microscope that will allow optical and electronic data to be collected from individual nanoparticles. An understanding of how the properties of nanomaterials are influenced by these various factors will extend knowledge of the basic properties of matter, as well as point to new synthesis strategies to optimize the performance of this important class of materials. This award is supported through the NSF ADVANCE Fellows Program. The overall mission of the ADVANCE Program is to increase the participation of women in the scientific and engineering workforce through the increased representation and advancement of women in academic science and engineering careers.