Berlin 2005 – scientific programme

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O: Oberflächenphysik

O 47: Rastersondentechniken III

O 47.1: Talk

Tuesday, March 8, 2005, 15:45–16:00, TU EB202

Optical interaction between tip and substrate in apertureless SNOM — •Ruben Esteban, Ralf Vogelgesang und Klaus Kern — Max Planck Institute für Festkörperforschungg

Scanning near field optical microscopes (SNOM) have proved able to overcome the resolution limit and study light-matter interaction in nanometer sized structures. Resolution of ∼ 10 nm is achievable at optical and infrared frequencies using the apertureless configuration (a-SNOM), which detects the fields scattered when a sharp tip is approached to a substrate under focused illumination. We use numerical simulation to better understand the phenomena involved. In our modelling we go significantly beyond the “spherical tip” model towards realistic, extended, conical tips. We can approach the experimental, “infinite-tip” case very well, including the presence of a large background field from the tip bulk. We also simulate the behavior of an efficient demodulation scheme that helps to discriminate the field generated in the strongly localized tip-substrate interaction. Good qualitative agreement with experimental measurements is found.