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High-resolution microscope for tip-enhanced optical processes in ultrahigh vacuum. Jens Steidtner Fritz Haber Institute, Physical Chemistry Department. Outline. Lateral resolution of aSNOM aSNOM - Optical configurations Focusing with a parabolic mirror Experimental setup
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High-resolution microscope for tip-enhanced optical processes in ultrahigh vacuum Jens Steidtner Fritz Haber Institute, Physical Chemistry Department
Outline • Lateral resolution of aSNOM • aSNOM - Optical configurations • Focusing with a parabolic mirror • Experimental setup • Experimental results • Outlook 2
Overcoming the diffraction limit Rayleigh`s criterion: (a) SNOM with a metal-coated tapered fiber tip (b) Apertureless SNOM with a metallic probe 3
TERS - Optical configurations Bottom-illumination1 Side-illumination2 Top-illumination3 [1] R. Stöckle, Y. D. Suh, V. Deckert, R. Zenobi, Chem. Phys. Lett. 318, 131 (2000) [2] B. Pettinger, G. Picardi, R. Schuster, G. Ertl, J. Electroanal. Chem. 554, 293 (2003) [3] J. Steidtner, B. Pettinger, Rev. Sci. Instrum., in print 5
Focusing with a parabolic mirror Linear polarization Radial polarization Si phonon band at 520 cm-1 6
Raman imaging the focus Linear polarization Radial polarization 10
TERS of BCB adsorbates BCB monolayer on Au(111) Brillant cresyl blue • ~36000 molecules are in the focal spot • Only 90 molecules are in the tip-enhanced region • By approaching the tip the signal is raised by a factor of 3920 • This equals a Raman enhancement factor of 1.6*106 11
Single molecule aSNOM Lateral resolution of ~15 nm 14
Outlook • Implementation of a combined AFM/STM scanner • Application of silver tips • Investigation of catalytic reactions on single crystals and oxide supported metal clusters 16
Acknowledgement • Dr. Bruno Pettinger • Workshops of the Fritz Haber Institute • Danish Micro Engineering • Fritz Haber Institute of the MPS 17