The aim of my project is to perform in-situ imaging of iron oxide nanoparticles during nucleation and growth. From a scientific standpoint, the dynamics of such nanoscale systems remain relatively unexplored. This is particularly true of magnetic materials. Additionally, a better understanding of nanoparticle formation will aid in the tailoring of physical and magnetic properties, crucial to the safe and effective biomedical application of these materials.
I am working jointly with Dr. Nigel Browning's group at the Pacific Northwest National Laboratory (PNNL). The group has developed novel in-situ liquid phase, and dynamic Transmission Electron Microscopy (TEM) techniques. These technologies will allow for high spatial and temporal resolution imaging of nanoparticles during the initial stages of formation. A specially designed sample holder allows for microscopy of liquid samples. The solution is sandwiched between two thin, transparent silicon nitride windows. Images can be taken of chemical reactions and processes occurring inside the cell. Dynamic TEM makes use of synchronized laser pulses to trigger electron emission and simultaneously initiate reaction in the sample. As in conventional TEM, electrons are directed down column, through a series of lenses, to the sample and are collected on a scintillator screen, or CCD. In DTEM, however images can be synchronized with reactions and captured with picosecond resolution.
Our iron oxide nanoparticles are manufactured via thermal decomposition of iron oleate. My intentions are to prepare a similar precursor solution in the liquid stage of the DTEM. Thermal decomposition and subsequent nanoparticle formation can be initiated by the DTEM's sample laser, heating of the stage, or another method. Utilizing the microscopes sub-nanometer and sub-nanosecond resolutions, we hope to observe atomic interactions during initial stages of nanoparticle growth. The culmination of these technologies holds the potential to study never before seen nucleation events and atomic interactions.