Zhili Zhang

UTK mechanical, aerospace, and biomedical engineering

Fundamental discoveries in science and engineering rarely get the press they deserve.

One such discovery occurred in the last decade when scientists succeeded in “squeezing” spectral light into sub-wavelengths and thus revolutionized conventional optics for the purpose of studying nanoparticles.

This breakthrough enables close examination of surfaces at the metal/dielectric (insulating) interface and, if current experimentation is successful, promises dramatic innovations in renewable energy, single molecule spectroscopy, and signal transmission.

JDRD Project: Active control of surface plasmonics for nanoscale diagnostics;
LDRD Project: Active control of surface plasmonics with ferroelectricity, Jian Shen.

Basically, nanoparticles are inserted into an impressive new material (LuFe2O4 ) recently engineered and fabricated at ORNL; then small amounts of voltage are applied, in a sense “tuning” the surface spectral response. In this way the specially-engineered surfaces can adapt to different environments such that diverse applications are possible with a single device. For example, in third-generation photovoltaic devices, nanostructures on the surface could automatically track solar spectra from ultraviolet to infrared and adjust to changing conditions for maximum efficiency.

While previous investigations along these lines have been limited to static (passive) structures, calibrating by applying voltage to the surface material allows for far greater control and discernment of nanoparticles, both in changing environments and in diagnoses of the special, dynamic characteristics of flow. For instance, the technique could potentially be critically important in aerospace engineering for diagnosing hypersonic flow around and about external surfaces of vehicles in flight.

JDRD researcher Zhili Zhang, undergraduate research assistant Jeremy Petersen, and the rest of the team, will use Surface Enhanced Raman Scattering (SERS) spectroscopy and a new fiber optic laser purchased specifically in support of this project to validate both experimentally and by computer modeling the properties of the new material fabricated by ORNL. Their results will provide feedback and a comprehensive analysis to the LDRD team led by Jian Shen.