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DS: Fachverband Dünne Schichten

DS 18: Symposium: In situ Optics I

DS 18.2: Hauptvortrag

Mittwoch, 28. März 2007, 15:30–16:00, H34

Optical Spectroscopy with high Spatial Resolution — •Wolfgang Richter, Eugen Speiser, Benjamin Buick, and Silvano Del Gobbo — U Roma2 "Tor Vergata", Roma, Italy

Optical spectroscopy, energetically and interactionwise, is one of the ideal experimental tools to study the physical properties of materials. On the other hand, the properties of such materials are modified nowadays in a controlled manner by reducing the physical size in one or more dimensions down into the nanometer scale. For such a situation, standard optical equipment has a non-sufficient spatial resolution, because it detects the secondary radiation from the sample in distances much larger than the wavelength (Far-Field) which gives at best (confocal microscope) a spatial resolution of several 100 nm using visible light. The reason for this limited resolution is that finer details of the sample are carried only in the evanescent fields, detectable only in subwavelength distance from the sample (Near-Field). By putting, however, a Nano-sized structure (small aperture, sharp metallic tip) within wavelength distance near the sample the evanescent waves can be converted into propagating waves which then can be detected in far field. This is the scope of Near Field Optics or Nano-Optics. While this secondary radiation is widely used for nanoscale imaging (Near Field Optical Microscopy) we will concentrate here on optical spectroscopy with nanoscale spatial resolution. We will focus especially the apertureless techniques, with their definite intensity advantage and concentrate mainly on Raman scattering. The experimental considerations and measurements on semiconductor nanorods will be discussed.