Seminars Archives
May 2005 | June 2005 | July 2005| Thursday, June 02, 2005 |
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"Local field confinement at metallic nanostructures: optical antennas for ultrahigh resolution microscopy and spectroscopy." Markus B. Raschke, Max-Born-Institut, Berlin 12pm, Room 260, Wright-Rieman Chemistry Laboratory ABSTRACT: The optical antenna properties of nanoscopic metal tips to detect, transfer and concentrate light to highly confined regions can be employed for near-field imaging. Making use of the local field enhancement at the tip apex, spectroscopic imaging with sub-10 nm spatial resolution will be demonstrated. For both linear and nonlinear light scattering the nature of the tip-sample coupling will be discussed in terms of dielectric properties, resonant plasmon excitation and symmetry: A) With the expansion of the technique into the infrared spectral region imaging of nanodomains of block-copolymer surfaces based on vibrational contrast has been achieved. B) In resonance Raman scattering sensitivity down to the single molecule level has been made possible by the plasmonic enhancement of the tip scattering response. C) In nonlinear light scattering the partially asymmetric tip geometry allows for the distinction of different nonlinear source polarizations and enables simultaneous surface and bulk investigations. |
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