Regensburg 2007 – wissenschaftliches Programm

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DS: Fachverband Dünne Schichten

DS 15: Poster Session

DS 15.8: Poster

Dienstag, 27. März 2007, 15:00–17:00, Poster B

Optical Investigation of Thin Photochromic Spiropyran Films — •Martin Schübbe, Michael Karcher, Celine Elsäßer, Christoph Rüdt, and Paul Fumagalli — Freie Universität, Berlin, Deutschland

Photochromic molecules, such as spiropyrans, can be reversibly switched between two different states, a so-called spiropyran and a merocyanine state, using ultraviolet and visible light. Hence, they can be read and addressed by a light source and thus be used for optical devices. Although this switching behavior is established for a series of photochromic molecules in an isotropic environment like, e.g., solutions [1,2], little is known about thin organic films on surfaces.

Here, thin films of spiropyran derivatives with a thickness between 10 and 40 nm have been prepared using thermal evaporation in UHV on quartz, MgO(100), Si(100), Si(111) and Au-coated Si as substrates. The photochromism of the molecules has been studied using optical absorption spectroscopy in the UV-VIS range. The films on quartz and MgO substrates were measured in transmission, the films on Si and Au-coated Si substrates in reflection. Absorption spectra indicate 80 % reversible switching between the spiropyran and the merocyanine state induced by light irradiation. In addition, a setup for time-dependent absorption spectroscopy on a time scale of seconds is presented together with first experimental results.

[1] Berkovic et al., Chem. Rev., 100, 1741-1753 (2000)

[2] Görner, PCCP, 3, 416-423 (2001)