Berlin 2001 – scientific programme

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CPP: Chemische Physik und Polymerphysik

CPP 17: Poster: Spectroscopy and Single Particle Spectroscopy of Molecular Systems, Photoprocesses, Biological Systems

CPP 17.13: Poster

Tuesday, April 3, 2001, 12:30–15:00, AT1

Detection of single molecules using molecular exciton microscopy (MEM) — •Elisabeth Paule and Peter Reineker — Theo. Physik, Universität Ulm, 89069 Ulm, Germany

Scanning near–field optical microscopy (SNOM) allows for the investigation of subwavelength structures. The size of the probe tip determines the spatial resolution. Single-molecule probes may result molecular resolution[1]. By using a MEM[2] single molecules on an organic surface should be detected. We present a theoretical framework to calculate the detected intensity in dependence on the wavelength of the incident electric field and the distance between tip and sample. The tip and sample are treated quantum mechanically. The electromagnetic field is described classically. Using a selfconsistent solution of the Schrödinger and the Maxwell equations we calculate the intensity which is observed in the far field. Numerical investigations allow to explain the realization of the contrast in the x-y-scans. Out of resonance there is a uniform contrast in each distance between the tip and the sample and the resolution decreases with increasing distance. In the range of resonance contrast and resolution depend sensitively on the distance.

[1] Michaelis, J., et. al. Nature 405 (2000) 325.

[2] Liebermann, K., et. al. Science, 247 (1990) 59.