Absorption Spectroscopy and Imaging from the Visible through Mid-IR with 20 nm Resolution Using AFM Probes

Correlated nanoscale composition and optical property maps are important to engineer nanomaterials in applications ranging from photovoltaics to sensing and therapeutics. Light absorption in the visible and near-IR probes electronic transitions, providing information on the band gap and defects. Light absorption in mid-IR probes vibrational transitions and provides information on chemical composition.

Single molecule dynamics at soft interfaces: from basic science to a $100,000,000,000 problem

Practical goals in materials engineering include minimal cost, maximum efficiency, and optimized longevity. As our experimental and theoretical methods to study nature’s molecular-scale design principles have improved, we have begun to understand that one reason nature can be so successful is that her engineering strategy often differs from ours.

Unconventional vibrational fingerprints at the scanning tunneling microscope junction: A personal look at tip-enhanced Raman spectroscopy

Scanning tunneling microscopy (STM) is an attractive tool to be complemented by optical spectroscopy because the molecule under optical interrogation can be directly visualized with the otherwise unattainable angstrom resolution. The simplest ensuing technique from that combination is tip-enhanced Raman spectroscopy (TERS). TERS utilizes a localized surface plasmon (LSP) at the tip apex to enhance the Raman signal. It is the gap-mode LSP that is sensitive to the gap distance, thereby provides the spatial resolution better than the diffraction limit.

Designing Absorption with Nanophotonics: from Photovoltaics to Chiral Metamaterials

Subwavelength nanostructures enable the manipulation and molding of light in nanoscale dimensions. This talk will first discuss the opportunities for enhancing photovoltaic performance using nanophotonic design, with a focus on recent work addressing luminescent solar concentrators. The combination of narrow band light emitting nanocrystals with wavelength-selective photonic materials enables high concentration ratios while capturing diffuse, rather than direct, sunlight and thereby improves photovoltaic performance.

On-Chip Integrated Nanowire Device with Controlled Nanogap for Electrical Characterization at Nanoscale Junctions

Electric field assisted precise positioning of Au and Ag segmented nanowires from dispersion onto a patterned chip surface has shown to be a facile, reliable and economical approach to create nanometer separated electrodes. The talk covers steps of fabrication of nanogap electrodes from the electrofluidically aligned nanowires and the performance of these devices in electrical measurement of different  molecular biorecognition. The main theme of the talk will be on creation of on-chip integrated nanowire device with controllable nanogap.

Cooperative Function in Atomically Precise Nanoscale Assemblies

We use molecular design, tailored syntheses, intermolecular interactions, and selective chemistry to direct molecules into desired positions to create nanostructures, to connect functional molecules to the outside world, and to serve as test structures for measuring single or bundled molecules. Interactions within and between molecules can be designed, directed, measured, understood, and exploited at unprecedented scales. Such interactions can be used to form precise molecular assemblies, nanostructures, and patterns, and to control and to stabilize function.

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