James R. Cournoyer

Generation and assembly of spheroid-like particles.

This paper reports a straightforward approach in generating spheroid-like particles and also the orientational orders observed in the self-assembly of these particles. Nonspherical particles, such as spheroid-like particles, are useful in both fundamental studies and industrial applications due to the geometry impact that they bring to the bulk properties of various material systems. Developing processes to generate nonspherical particles is an ongoing quest to meet the need of using such particles in different applications. The approach reported here takes advantage of a controlled chemical etching process. Exposing the spherical silica particles partially to carbon tetrafluoride in a reactive ion plasma-etching chamber transformed the particles from spherical shape into spheroid-like shape. A simple model is proposed to predict the geometry of the resulting nonspherical particles. The shape and dimension of the nonspherical particles generated through such a process matched well with the prediction of the model. The assembly of these spheroid-like particles showed a unique orientational order associated with the alignment of their axes. This approach will help further studies on the fundamental properties of the nonspherical particles, such as packing, rheology, and optical interaction.

Exploration of a Butterfly Wing Using a Diverse Suite of Characterization Techniques

Much effort is currently being expended in nanotechnology and other fields to build biometric, or nature-inspired, materials. The first step in this process is often to develop a more complete understanding of the structure and chemistry of biological systems. In this presentation, we will compare and contrast data collected on a simple biological sample, a butterfly wing, using a variety of analytical techniques. Transmission Electron Microscopy (TEM) was used in order to perform high lateral resolution imaging of the sample cross section [1]; Optical Microscopy (OM) and Scanning Electron Microscopy (SEM) were used to provide structural information of the outer wing surface at various magnifications [1]; Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) was used in order to image the chemical composition of the outer most surface layer; and Focused Ion Beam (FIB) techniques were used to cut (micro machine) features into the wing [1]. Each of these analytical techniques have sample preparation and data collection challenges which will be summarized and compared [1]. We will demonstrate that these analytical techniques provide complimentary information which helps the researcher understand the sample.

Solar Review: Characterizing Thin Film Photovoltaics

Materials characterization plays critical role in the development of new materials and technologies. In this paper, we review recent worldwide progress in solar CdTe and CIGS thin film technologies including device background, materials challenges and corresponding approaches to characterization, with particular emphasis on probing at nano-scale. Significant characterization breakthroughs will be discussed as well as the most challenging aspect of each materials system.