Polarized and Evanescent Guided Wave Surface-Enhanced Raman Spectroscopy of Ligand Interactions on a Plasmonic Nanoparticle Optical Chemical Bench.

This study examined applications of polarized evanescent guided wave surface-enhanced Raman spectroscopy to determine the binding and orientation of small molecules and ligand-modified nanoparticles, and the relevance of this technique to lab-on-a-chip, surface plasmon polariton and other types of field enhancement techniques relevant to Raman biosensing. A simplified tutorial on guided-wave Raman spectroscopy is provided that introduces the notion of plasmonic nanoparticle field enhancements to magnify the otherwise weak TE- and TM-polarized evanescent fields for Raman scattering on a simple plasmonic nanoparticle slab waveguide substrate. The waveguide construct is called an optical chemical bench (OCB) to emphasize its adaptability to different kinds of surface chemistries that can be envisaged to prepare optical biosensors.

Insights into Permanent Encodings of Macroscopic Spike Patterns by Magnetic-Field-Directed Evaporative Self-Assembly from Ferrofluids.

Field-directed assembly has the potential to make large hierarchically ordered structures from nanoscale objects. Shear forces and optical, electric, and magnetic fields have been used for this purpose. Ferrofluids consist of magnetic nanoparticles hosted in mobile liquids.

Resonance Raman Vibrational Mode Enhancement of Adsorbed Benzenethiols on CdSe Is Predominantly Franck-Condon in Nature and Governed by Symmetry.

Here, we report mode-specific resonance Raman enhancements of ligands covalently bound to the surface of colloidal CdSe nanocrystals (NCs). By the systematic comparison of a set of structural derivatives, the extent of resonance Raman enhancement is shown to be directly related to the molecular symmetry of the bound ligands. The enhancement dependence on molecular symmetry is further discussed in terms of Franck-Condon and Herzberg-Teller contributions and their associated selection rules.

Visible laser self-focusing in hybrid glass planar waveguides.

We report that self-focusing occurs with simultaneous self-inscription of a cylindrical waveguide when 514.5-nm light from a cw argon-ion laser propagates in a solgel-derived silica methacrylate hybrid glass planar waveguide. Spatially localized free-radical polymerization of methacrylate substituents is initiated in the path of the guided wave.