Darmstadt 2008 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 55: Poster Laseranwendungen

Q 55.1: Poster

Thursday, March 13, 2008, 16:30–19:00, Poster C2

Absorption spectroscopy of isolated molecules using sub-wavelength diameter optical fibres — •Ariane Stiebeiner, Ruth García Fernández, and Arno Rauschenbeutel — Institut für Physik, Universität Mainz, Staudingerweg 7, 55128 Mainz

Particles on the surface of sub-wavelength diameter air-clad fibres are strongly coupled to the pronounced evanescent field of the fibre guided modes. This makes such fibres a powerful tool for absorption spectroscopy of surface-adsorbed molecules, based upon the measurement of the reduction in fibre transmission. We have shown that the corresponding detection sensitivity for a given surface coverage of molecules can be orders of magnitude higher than for conventional techniques [1].

We present an improved setup for the detection of small numbers of isolated molecules at room temperature. The measurements are carried out on different species of organic molecules in a dry nitrogen atmosphere, thus permitting spectroscopy of molecules that are not stable under ambient conditions. Also, due to the absence of water in this atmosphere, reordering processes to monolayer islands or even a polycrystalline phase, which are possible for some molecular species, will be slowed down, enabling us to prepare and observe molecules on the fibre surface for extended periods of time.

[1] F. Warken et al., Opt. Express, 15, 11952-11958 (2007)