Characterization of nanoparticles using electron microscopy

Ryan Thompson, advisors: C. Barry Carter (CEMS), Steve Campbell (ECE)

My research is focusing on the characterization of nanoparticles using various microscopy techniques. The transmission electron microscope (TEM) is indispensable in the characterization of nanoscale materials as it combines a large field of view at lower magnifications with the ability to image at the atomic level. Thus, specific particles may be selected for analysis. Structural and chemical characterization is possible using a variety of methods such as high-resolution electron microscopy (HREM), selected area diffraction (SAD), convergent-beam electron diffraction (CBED), electron energy loss spectrometry (EELS), X-ray energy-dispersive spectrometry (XEDS), and energy-filtered imaging (EFI).

However, TEM is limited by its stringent sample requirements. Scanning electron microscopy (SEM) may be used as an alternate or complementary method to image larger particles and for chemical analysis without the limitations imposed by TEM. For delicate samples, a focused ion beam (FIB) tool is especially useful when conventional mechanical and chemical polishing methods are not feasible. Sample preparation using the FIB has the advantages of producing large regions of electron transparency, site-specificity, and prevention of artifacts normally introduced using mechanical techniques.

Future work in my research includes investigation of defects in nanoparticles, and comparison of defect character with their bulk material counterparts, development of techniques for sample preparation, and to provide chemical and structural feedback to the nanoparticle production groups.