Browsing by Author "Chang, Albert"

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    Exploration of Chemical Analysis Techniques for Nanoscale Systems
    (2013-09-16) Chang, Albert; Kelly, Kevin F.; Natelson, Douglas; Hafner, Jason H.
    As the critical dimensions of many devices, especially electronics, continue to become smaller, the ability to accurately analyze the properties at ever smaller scales becomes necessary. Optical techniques, such as confocal microscopy and various spectroscopies, have produced a wealth of information on larger length scales, above the diffraction limit. Scanning probe techniques, such as scanning tunneling microscopy and atomic force microscopy, provide information with an extremely fine resolution, often on the order of nanometers or angstroms. In this document, plasmon coupling is used to generate large signal increases, with clear future applications toward scanning probe optical spectroscopies. A variation on scanning tunneling microscopy is also used to study the surface structure of environmentally interesting nanoparticles. Traditional Raman spectroscopy is used to examine doped graphene, which is becoming a hot material for future electronic applications.
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    Plasmon coupling between a gold colloid and a gold film and its implications on tip enhanced Raman spectroscopy
    (2007) Chang, Albert; Kelly, Kevin F.
    Engineering of plasmon resonances is important for a variety of applications, including but not limited to surface enhanced Raman spectroscopy (SERS) and near field scanning optical microscopy (NSOM). Of special interest are systems where the plasmon is coupled between a nanoparticle and a thin gold film. This coupling allows for a greater degree of control of the plasmon resonance of the system, as well as a strong, localized, enhancement of the incident electric field. We demonstrate that this coupling, and the resulting enhancement, can be used for SERS applications, and explore its impact on potential NSOM applications.