El-Sayed and his group are studying the ultrafast electronics optical and ultrafast relaxation properties of both Noble metal and semiconductor nanoparticle as well as the catalytic properties of transition metal nanoparticles as a function their size and shape. Unravelling the properties of nanoparticles assist the nanotechnologists in using them in appropriate applications. For ultrafast dynamic studies, their Laser Dynamics Lab facilities are used. The shape dependence of the optical studies enables the technologist to tune the color of gold or silver nanocrystals. The nonradiative relaxation of the electronic motion leads to coherent oscillation of the lattice of the nanoparticles allowing its optical (and electric) properties to be modulated at the oscillation frequency. This ability to tune and modulate these properties should be useful in the optoelectronic and photonic applications of gold and silver nanoparticles.
The ability of these nanoparticle to strongly absorb or strongly scatter light at a certain frequency is shown quantitatively to depend on the shape and size of the nanoparticle. This group used this property recently to detect one cancer cell by conjugating these particles to antibodies that binds mostly to cancer cells and not to healthy cells.
In a Science report, the El-Sayed's group were the first to synthesize metallic nanoparticles of different shape. It would be quite profitable if one can determine the type of reactions each shape would catalyze. Selectivity in catalysis saves a great deal of energy and money in reducing the need for exhaustive and expensive separation costs. Different nanocrystal shapes have different facets and different defect structures that could impose electronic and sterric requirements in their catalytic functions. The El-Sayed's group is also studying different techniques to stabilize the nanocrystal shapes, which due to their high surface energies, could be reactive and unstable in the harsh reactive environment.
El-Sayed's group is also studying the rapid electronic cooling in excited semiconductor nanoparticles of different sizes, shapes and composition. The understanding of the rapid dynamics properties of these nanoparticles is important in many future applications in the field of nanoelectronics.