Regensburg 2010 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 56: Metal substrates: Adsorption of organic / bio molecules VI
O 56.2: Vortrag
Mittwoch, 24. März 2010, 15:15–15:30, H36
Optical Isomerization of tetra(tert-butyl)azobenzene (TBA) on Gold (111) and Coverage Dependent Conformation of the Corresponding Imine — •Daniel Brete1, Roland Schmidt1, Cornelius Gahl1, Robert Carley1, Sebastian Hagen2, Petra Tegeder2, and Martin Weinelt1,2 — 1Max-Born-Institut, Max-Born-Str. 2A, 12489 Berlin — 2Freie Universität Berlin, Fachbereich Physik, Arnimallee 14, 14195 Berlin
NEXAFS and XPS have been used to investigate optically induced conformational changes of 3,3’,5,5’-tetra(tert-butyl)azobenzene (TBA) monolayers and the influence of coverage and temperature on the conformation of the analogue imine 3,5-di-tert-butylbenzaldehyde-(3,5-di-tert-butyl-phenylimine)(TBI) on gold (111) surfaces.
Monolayers of TBA adsorb flat on the surface. Upon illumination with blue light TBA is transformed into a non-planar configuration. This change is thermally reversible. The photoisomerization cross section of TBA is reduced by two orders of magnitude compared to solution suggesting a substrate induced photoisomerization mechanism.
In contrast the monolayer of TBI exhibits a non-planar configuration, while submonolayers obtained by partial desorption exhibit a planar adsorbtion geometry. Both are very similar to the non-planar and planar species of TBA. We conclude that the energy gained by a higher packing density favours the non-planar configuration in the case of TBI.