Departmental Colloquium

Nanoscale Optical Spectroscopy and Detection

Lukas Novotny
University of Rochester, Institute of Optics

Time
Wed. December 7, 2005     1:00 PM     Stirling C

Abstract

Recently, near-field optics has extended the range of optical measurements beyond the diffraction limit and stimulated interests in many disciplines. I will present a near-field optical technique that makes use of the strongly enhanced electric field close to a sharply pointed metal tip under laser illumination. The tip is held a few nanometers above the sample surface so that a highly localized interaction between the enhanced field and the sample is achieved. The method has been successfully combined with vibrational spectroscopy by making use of the well-known effect of surface enhanced Raman scattering (SERS). We mapped out the vibrational modes of individual single-walled carbon nanotubes (SWNT) with a resolution of 20nm and measured fluorescence enhancement and quenching on single molecules. (a) Confocal and (b) near-field Raman scattering images of the same area of a carbon nanotube sample acquired at  nu= 2615 cm^−1 (G′-band). (c) The Raman scattering spectrum uniquely identifies the chemical nature of the sample.

Lunch will be available in Stirling C before the talk!

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