Speaker: Jin Zhang, UC Santa Cruz
Date & Time: April 13, 2006 - 12:00pm
Location: Room 260, Wright-Rieman Chemistry
Novel Optical and Dynamic Properties and Emerging Applications of Semiconductor and Metal Nanomaterials
Laboratory for Surface Modification
Jin Zhang, UC Santa Cruz
12:00 Noon, Room 260, Wright-Rieman Chemistry
Nanomaterials are of strong interest for both fundamental and technological reasons. At the fundamental level, nanomaterials possess novel physical and chemical properties that differ from those of isolated atoms or molecules and bulk matter due to quantum confinement effects and exceedingly larger surface area relative to volume. These novel properties are highly promising for applications in emerging technologies such as nanoelectronics, nanophotonics, non-linear optics, miniaturized sensors and imaging devices, solar cells, and detectors.
Semiconductor nanoparticles have been studied extensively because of their potential application in electronic devices and the opportunity they offer to study the effects of quantum confinement. A unique subset of semiconductor nanoparticles is doped semiconductor nanoparticles. We have recently studied several doped semiconductor nanoparticle systems with the goal to understand the relation between their optical properties and the structure of the host nanoparticles as well as that of the dopant. In the case of Mn2+-doped ZnSe nanoparticles, we have found that the location of the Mn2+ significantly influences its optical emission properties. This understanding is important for designing new nanophotonics materials. We have also investigated the bioconjugation of silica-coated CdSe quantum dots to IgG proteins for potential applications in cancer biomarker detection and have found that the silica coating significantly enhance the stability of the CdSe quantum dots in buffer solutions based on photoluminescence properties.
Metal nanoparticles have also attracted considerable attention due to their interesting properties and potential applications. We have studied the optical and structural properties of different metal nanostructures including aggregates, nanorods, and nanoshells with the goal to optimize their SERS (surface-enhanced Raman scattering) activities. For example, we have very recently demonstrated SERS from single, hollow gold nanostructures. Exceptional sample homogeneity leads to a nearly tenfold increase in signal consistency over standard silver substrates. SERS offers a unique combination of molecular specificity and extremely high sensitivity that few other analytical techniques can offer. SERS based on metal nanoparticles, in conjunction with photoluminescence from semiconductor quantum dots, have been exploited for detection of cancer biomarkers.