Berlin 2012 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 64: Plasmonics and nanooptics III

O 64.8: Vortrag

Donnerstag, 29. März 2012, 12:15–12:30, MA 005

Near-field Spectroscopic Imaging with Parabolic Mirror Assisted Gap-Mode Optical Microscopy — •Kai Braun, Dai Zhang, Xiao Wang, and Alfred J. Meixner — Institut für Physikalische und Theoretische Chemie, Universität Tuebingen, Germany

The recognition and identification of individual components is essential in many scientific issues. Raman microscopy is well established to detect chemical contrasts, however with a diffraction limited resolution. In this work we will present our recent work of high-resolution spectroscopic imaging using parabolic mirror assited gap-mode optical microscopy. A high NA parabolic mirror has been adopted in this new type of microscope as focusing and collecting element [1] which enables to investigate opaque samples with the highest NA achievable in air. Optical field enhancement is achieved in the gap between a sharp Au-tip and the substrate. The tip is excited efficiently by a radially polarized laser beam [2]. The optical signal emerging from the gap is simultaneously collected by an avalanche photo diode and a spectrometer. In addition the simultaneously obtained topographic information can be used for analysing the morphology correlated local material distribution We will show topographic and spectroscopic imaging of different components in a modified Diamond like Carbon (DLC) film etc. We demonstrate the prospective application of this microscope in a variety of important fields.

[1] M. A. Lieb, A. J. Meixner, Opt. Exp. 2001, 8, 456. [2] D. Zhang et all. PRL, 2010, 104, 5.