Stuttgart 2012 – wissenschaftliches Programm

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MO: Fachverband Molekülphysik

MO 8: Photochemistry

MO 8.2: Vortrag

Dienstag, 13. März 2012, 10:45–11:00, V38.02

Control of photochromic molecules adsorbed to optical microfibres — •Ulrich Wiedemann, Wolfgang Alt, and Dieter Meschede — Institut für Angewandte Physik, Universität Bonn, Wegelerstraße 8, 53115 Bonn

The high light intensity on the surface of an optical microfibre can be used for strong light-matter interaction experiments with surface adsorbates. In previous experiments in our group ultra-sensitive absorption spectroscopy of surface-adsorbed organic dye molecules has been demonstrated [1]. After the passive observation of organic dyes, the next level of complexity is the optical manipulation of photochromic molecules. Switching between the molecular states is achieved by exposure to the evanescent field of a few nanowatts of UV or white light guided in the microfibre. The internal state of the molecules is detected via their state-dependent light absorption.

We present a quantitative analysis of the time-resolved photoswitching dynamics, which are measured and mathematically modelled with a rate equation model. By adjusting the microfibre evanescent field strength the dynamic equilibrium state of the molecules is controlled. Finally, we investigate how many times the photochromic system can be switched before undergoing significant photochemical degradation.
[1] F. Warken, E. Vetsch, D. Meschede, M. Sokolowski, and A. Rauschenbeutel, “Ultra-sensitive surface absorption spectroscopy using sub-wavelength diameter optical fibers,” Opt. Express 15(19), 11952–11958 (2007).