Dresden 2006 – scientific programme

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O: Oberflächenphysik

O 6: Scanning probe techniques I

O 6.3: Talk

Monday, March 27, 2006, 11:45–12:00, WIL B321

Optical versus mechanical contrast mechanism in dynamic apertureless SNOM — •Ralf Vogelgesang, Alpan Bek, Ruben Esteban, and Klaus Kern — Max Planck Institut für Festkörperforschung

In dynamic mode apertureless or scattering-type scanning near-field optical microscopy (SNOM) an oscillating scanning probe tip excites optical interactions at a surface. Ideally, the local optical information can be extracted by lock-in amplification at a higher harmonic of the oscillation frequency. This signal, however, is easily contaminated by mechanical crosstalk.

We have developed a quantitative model to specify the proper conditions [1]. We show that the contrast mechanism is in general a combination of both spatially nonlinear optical interaction and temporally anharmonic mechanical tip motion. Our algebraic analysis provides a systematic framework to identify and control the relative influence of the competing contrast origins.

[1] A. Bek, R. Vogelgesang, and K. Kern, Appl. Phys. Lett., 87, 163115 (2005)