Hamburg 2001 – wissenschaftliches Programm

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O: Oberflächenphysik

O 25: Postersitzung (Grenzfl
äche fest-flüssig, Methodisches, Nanostrukturen, Organische Dünnschichten, Rastersondentechniken, reine Oberfl
ächen, Teilchen und Cluster, Zeitaufgelöste Spektroskopie, Sonstiges)

O 25.48: Poster

Mittwoch, 28. März 2001, 15:00–18:00, Foyer zu B

SNOM imaging of monolayers of aggregated dye molecules by Scanning probe enhanced elastic resonant scattering (SPEERS) — •J. Heimel, U.C. Fischer, and H. Fuchs — Physikalisches Institut, Westfälische Wilhelms-Universität, Münster, Germany

We succeeded recently to obtain clear images of small domains in a monolayer of J-aggregated dye molecules by using a SNOM (Scanning Near Field Optical Microscope) with the tetrahedral tip as a light emitting probe and using an auxiliary STM mode for distance control [1,2]. Domains as small as 10 - 20 nm could be imaged with a high contrast especially well in a depolarized imaging mode [3]. Assuming the brickstone structure of such J-aggregates as revealed by STM [4], we estimate that a number of 10 - 40 molecules give rise to the contrast in such a small area. Presently the possibility to image single molecules by the SNOM at molecular resolution is being explored. The surprisingly large contrast is tentatively explained by a scanning probe enhanced elastic resonant scattering (SPEERS).

This work was supported by the Volkswagen Foundation

[1] J. Koglin, U.C. Fischer, H. Fuchs. Phys. Rev. B 55 (12), 7977-7984 (1997)

[2] J. Heimel, U.C. Fischer, H. Fuchs. J. Microscopy, in print

[3] J. Heimel et al. to be published