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          Institute: Fritz-Haber-Institut     Collection: Physical Chemistry     Display Documents

ID: 433630.0, Fritz-Haber-Institut / Physical Chemistry
Reversible photoisomerization of an azobenzene-functionalized self-assembled monolayer probed by sum-frequency generation vibrational spectroscopy
Authors:Wagner, Steffen; Leyssner, Felix; Kördel, Christian; Zarwell, Sebastian; Schmidt, Roland; Weinelt, Martin; Rück-Braun, Karola; Wolf, Martin; Tegeder, Petra
Date of Publication (YYYY-MM-DD):2009-05-20
Title of Journal:Physical Chemistry Chemical Physics
Journal Abbrev.:Phys. Chem. Chem. Phys.
Issue / Number:29
Start Page:6242
End Page:6248
Copyright:© 2009 Royal Society of Chemistry
Review Status:Peer-review
Audience:Experts Only
Abstract / Description:Sum-frequency generation (SFG) vibrational spectroscopy is employed to investigate the reversible, photoinduced trans/cis isomerization of an azobenzene-functionalized self-assembled monolayer (SAM) on a gold substrate. A C≡N marker group at the outer phenyl ring is used as a direct measure of the switching state. The azobenzene unit is connected to the surface by a tripodal linker system with an adamantane core, which results in both a sufficient decoupling of the functional azobenzene unit from the metallic substrate and a free volume to prevent steric hinderance, thus allowing the isomerization process. Optical excitation at 405 nm induces the trans → cis isomerization, whereas light exposure at 470 nm leads to the back reaction. The effective cross sections for the reactions are σeff(cis) = 4 ± 1 × 1018 cm2 at 405 nm (trans → cis) and σeff(trans) = 2.5 ± 0.9 × 1019 cm2 at 470 nm (cis → trans). We propose that the photoisomerization is driven by a direct (intramolecular) electronic excitation of the azobenzene conjugate, analogous to the free molecules in solution.
External Publication Status:published
Document Type:Article
Communicated by:Martin Wolf
Affiliations:Fritz-Haber-Institut/Physical Chemistry
External Affiliations:Wagner S, Leyssner F, Kördel C, Weinelt M, Wolf M, Tegeder P, FU Berlin, FB Physik, Arnimallee 14, 14195 Berlin, Germany; Schmidt R, Weinelt M, Max-Born-Inst, Max-Born-Str. 2A, 12489 Berlin, Germany; Zarwell S, Rück-Braun K, TU Berlin, Inst Chem, Str. 17. Juni 135, 10623 Berlin, Germany
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