@article{KoenigYadavalliSanter2012,
  author    = {K{\"o}nig, Tobias and Yadavalli, Nataraja Sekhar and Santer, Svetlana},
  title     = {Near-Field induced reversible structuring of photosensitive polymer films Gold versus silver nano-antennas},
  series = {Plasmonics},
  volume    = {7},
  journal   = {Plasmonics},
  number    = {3},
  publisher = {Springer},
  address   = {New York},
  issn      = {1557-1955},
  doi       = {10.1007/s11468-012-9339-3},
  pages     = {535 -- 542},
  year      = {2012},
  abstract  = {We report on reversible structuring of photosensitive azo-containing polymer films induced by near-field intensity patterns emanating from illuminated nano-scale metal structures fabricated by colloidal lithography. Two different sets of these nano-antennas, consisting of either gold or silver, were investigated with respect to their ability to induce topography changes in a photosensitive polymer film placed above. Using in situ recorded atomic force microscopy micrographs of polymer topography changes during UV irradiation, we find that the response of the polymer film differs for the two metals at similar geometries of the metal nanostructures. The maximum topography change is stronger for Ag antennas as compared to the Au pattern, whereas the latter material revealed a pronounced splitting of topography maxima into two, a phenomenon less visible in the case of Ag. Finite difference time domain simulations of the electromagnetic field distribution in the vicinity of the metal structures confirm this remarkable observation. The local intensity is twice as large for the Ag as compared to the Au structures, and in each case, a splitting of the intensity pattern results, with a stronger modulation for Au. For both metals, the topography change was found to be reversible between a patterned and a flat by repeated change of irradiation conditions.},
  language  = {en}
}
@article{YadavalliKoenigSanter2015,
  author    = {Yadavalli, Nataraja Sekhar and K{\"o}nig, Tobias and Santer, Svetlana},
  title     = {Selective mass transport of azobenzene-containing photosensitive films towards or away from the light intensity},
  series = {Journal of the Society for Information Display},
  volume    = {23},
  journal   = {Journal of the Society for Information Display},
  number    = {4},
  publisher = {Wiley-Blackwell},
  address   = {Hoboken},
  issn      = {1071-0922},
  doi       = {10.1002/jsid.306},
  pages     = {154 -- 162},
  year      = {2015},
  abstract  = {Here, we report on two photosensitive amorphous polymers showing opposite behavior upon exposure to illumination. The first polymer (PAZO) consists of linear backbone to which azobenzene-containing side chains are covalently attached, while in the second polymer (azo-PEI), the azobenzene side chains are attached ionically to a polyelectrolyte backbone. When irradiated through a mask, the PAZO goes away from the intensity maxima, leaving behind topography trenches, while the direction of the mass transport of the azo-PEI polymer points towards the intensity maxima. This kind of behavior has been reported only for certain liquid crystalline polymers that exhibit in-phase reaction on illumination, that is, topography maxima coincides with the intensity maxima. Furthermore, flat nanocrystals placed on top of azo-PEI film was found to be moved together with the mass transport of the underlying polymer film as visualized using in situ atomic force microscopy (AFM) measurements. It was also demonstrated that the two polymer films respond differently on irradiation with the polarization and intensity interference patterns (IPs). To record the kinetic of the surface relief grating formation within two polymers during irradiation with different IPs, we utilized a homemade setup combining the optical part for the generation of IP and AFM. A possible mechanism explaining different responses on the irradiation of amorphous polymers is discussed in the frame of a theoretical model proposed by Saphiannikova et al. (J. Phys. Chem. B 113, 5032-5045 (2009)).},
  language  = {en}
}