Berlin 2018 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 42: Poster: Organic-Inorganic Hybrid Systems and Organic Films

O 42.6: Poster

Dienstag, 13. März 2018, 18:15–20:30, Poster A

Photoisomerization characteristics of azobenzene-functionalized SAMs/Au(111) — •Wibke Bronsch, Larissa Boie, Thomas Moldt, Jan Böhnke, Beatrice Andres, Daniel Przyrembel, Cornelius Gahl, and Martin Weinelt — Freie Universität Berlin, Institut für Experimentalphysik, Arnimallee 14, 14195 Berlin

Self-assembled monolayers (SAMs) of azobenzene-functionalized alkanethiolates form molecular ensembles with preferential orientation and significant excitonic coupling among the azobenzene chromophores. It has been under debate if the excitonic coupling influences the trans-cis photoisomerization of the azobenzene units in the ensemble. In this contribution we use the sensitivity of the sample work function on the density of trans and cis isomers [1] to investigate this question by means of two-photon-photoemission. The photon-energy dependence of the photostationary state and the effective isomerization cross-sections in SAMs with different azobenzene content allows for disentangling different excitation pathways. It turns out that predominantly localized excitations contribute to photoswitching while the contribution of intermolecular coupled and thus delocalized excitonic states is minor [2].

[1] W. Bronsch, D. Przyrembel, L. Boie, C. Gahl and Martin Weinelt, Fast optical work-function tuning at an organic/metal interface, Appl. Phys. Lett. 111, 081601 (2017)

[2] W. Bronsch, T. Moldt, L. Boie, C. Gahl and Martin Weinelt, Delocalized versus localized excitations in the photoisomerization of azobenzene-functionalized alkanethiolate SAMs, J. Phys.: Condens. Matter 29, 484002 (2017)