@article{DiFlorioBruendermannYadavallietal.2014,
  author    = {Di Florio, G. and Bruendermann, E. and Yadavalli, Nataraja Sekhar and Santer, Svetlana A. and Havenith, Martina},
  title     = {Confocal raman microscopy and AFM study of the interface between the photosensitive polymer layer and multilayer graphene},
  series = {Soft materials},
  volume    = {12},
  journal   = {Soft materials},
  publisher = {Taylor \& Francis Group},
  address   = {Philadelphia},
  issn      = {1539-445X},
  doi       = {10.1080/1539445X.2014.945040},
  pages     = {S98 -- S105},
  year      = {2014},
  abstract  = {In this paper we report on the interaction between photosensitive azobenzene-containing polymer films and on top adsorbed graphene multilayers. The photosensitive polymer film changes its topography under irradiation with light interference patterns according to their polarization distribution. The multilayer graphene follows the deformation of the polymer film and stretches accordingly. Using confocal Raman microspectroscopy we can detect the appearance of additional peaks in the Raman spectrum of the photosensitive polymer film upon irradiation indicating a molecular interaction at the interface between the graphene multilayer and the polymer matrix. Multi-component analysis of the specific Raman bands shows that the interaction involves the graphene rings and the aromatic rings of the azobenzenes causing the strong adhesion between the two materials.},
  language  = {en}
}
@article{DiFlorioBruendermannYadavallietal.2014,
  author    = {Di Florio, G. and Bruendermann, E. and Yadavalli, Nataraja Sekhar and Santer, Svetlana A. and Havenith, Martina},
  title     = {Graphene multilayer as nanosized optical strain gauge for polymer surface relief gratings},
  series = {Nano letters : a journal dedicated to nanoscience and nanotechnology},
  volume    = {14},
  journal   = {Nano letters : a journal dedicated to nanoscience and nanotechnology},
  number    = {10},
  publisher = {American Chemical Society},
  address   = {Washington},
  issn      = {1530-6984},
  doi       = {10.1021/nl502631s},
  pages     = {5754 -- 5760},
  year      = {2014},
  abstract  = {In this paper, we show how graphene can be utilized as a nanoscopic probe in order to characterize local opto-mechanical forces generated within photosensitive azobenzene containing polymer films. Upon irradiation with light interference patterns, photosensitive films deform according to the spatial intensity variation, leading to the formation of periodic topographies such as surface relief gratings (SRG). The mechanical driving forces inscribing a pattern into the films are supposedly fairly large, because the deformation takes place without photofluidization; the polymer is in a glassy state throughout. However, until now there has been no attempt to characterize these forces by any means. The challenge here is that the forces vary locally on a nanometer scale. Here, we propose to use Raman analysis of the stretching of the graphene layer adsorbed on top of polymer film under deformation in order to probe the strength of the material transport spatially resolved. With the well-known mechanical properties of graphene, we can obtain lower bounds on the forces acting within the film. Upon the basis of our experimental results, we can deduce that the internal pressure in the film due to grating formation can exceed 1 GPa. The graphene-based nanoscopic gauge opens new possibilities to characterize opto-mechanical forces generated within photosensitive polymer films.},
  language  = {en}
}
@article{FilimonKopfSchmidtetal.2011,
  author    = {Filimon, Marlena and Kopf, Ilona and Schmidt, Dietrich A. and Bruendermann, Erik and R{\"u}he, J{\"u}rgen and Santer, Svetlana A. and Havenith, Martina},
  title     = {Local chemical composition of nanophase-separated polymer brushes},
  series = {Physical chemistry, chemical physics : a journal of European Chemical Societies},
  volume    = {13},
  journal   = {Physical chemistry, chemical physics : a journal of European Chemical Societies},
  number    = {24},
  publisher = {Royal Society of Chemistry},
  address   = {Cambridge},
  issn      = {1463-9076},
  doi       = {10.1039/c0cp02756a},
  pages     = {11620 -- 11626},
  year      = {2011},
  abstract  = {Using scattering scanning nearfield infrared microscopy (s-SNIM), we have imaged the nanoscale phase separation of mixed polystyrene-poly(methyl methacrylate) (PS-PMMA) brushes and investigated changes in the top layer as a function of solvent exposure. We deduce that the top-layer of the mixed brushes is composed primarily of PMMA after exposure to acetone, while after exposure to toluene this changes to PS. Access to simultaneously measured topographic and chemical information allows direct correlation of the chemical morphology of the sample with topographic information. Our results demonstrate the potential of s-SNIM for chemical mapping based on distinct infrared absorption properties of polymers with a high spatial resolution of 80 nm x 80 nm.},
  language  = {en}
}
@misc{DiFlorioBruendermannYadavallietal.2013,
  author    = {Di Florio, Giuseppe and Br{\"u}ndermann, Erik and Yadavalli, Nataraja Sekhar and Santer, Svetlana A. and Havenith, Martina},
  title     = {Polarized 3D Raman and nanoscale near-field optical microscopy of optically inscribed surface relief gratings},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-95233},
  pages     = {1544 -- 1554},
  year      = {2013},
  abstract  = {We have used polarized confocal Raman microspectroscopy and scanning near-field optical microscopy with a resolution of 60 nm to characterize photoinscribed grating structures of azobenzene doped polymer films on a glass support. Polarized Raman microscopy allowed determining the reorientation of the chromophores as a function of the grating phase and penetration depth of the inscribing laser in three dimensions. We found periodic patterns, which are not restricted to the surface alone, but appear also well below the surface in the bulk of the material. Near-field optical microscopy with nanoscale resolution revealed lateral two-dimensional optical contrast, which is not observable by atomic force and Raman microscopy.},
  language  = {en}
}
@article{DiFlorioBruendermannYadavallietal.2014,
  author    = {Di Florio, Giuseppe and Bruendermann, Erik and Yadavalli, Nataraja Sekhar and Santer, Svetlana A. and Havenith, Martina},
  title     = {Polarized 3D Raman and nanoscale near-field optical microscopy of optically inscribed surface relief gratings: chromophore orientation in azo-doped polymer films},
  series = {Soft matter},
  volume    = {10},
  journal   = {Soft matter},
  number    = {10},
  publisher = {Royal Society of Chemistry},
  address   = {Cambridge},
  issn      = {1744-683X},
  doi       = {10.1039/c3sm51787j},
  pages     = {1544 -- 1554},
  year      = {2014},
  abstract  = {We have used polarized confocal Raman microspectroscopy and scanning near-field optical microscopy with a resolution of 60 nm to characterize photoinscribed grating structures of azobenzene doped polymer films on a glass support. Polarized Raman microscopy allowed determining the reorientation of the chromophores as a function of the grating phase and penetration depth of the inscribing laser in three dimensions. We found periodic patterns, which are not restricted to the surface alone, but appear also well below the surface in the bulk of the material. Near-field optical microscopy with nanoscale resolution revealed lateral two-dimensional optical contrast, which is not observable by atomic force and Raman microscopy.},
  language  = {en}
}
@article{DiFlorioBruendermannYadavalletal.2014,
  author    = {DiFlorio, Giuseppe and Br{\"u}ndermann, Erik and Yadavall, Nataraja Sekhar and Santer, Svetlana A. and Havenith, Martina},
  title     = {Polarized 3D Raman and nanoscale near-field optical microscopy of optically inscribed surface relief gratings: chromophore orientation in azo-doped polymer films},
  issn      = {1744-683x},
  doi       = {10.1039/c3sm51787j},
  year      = {2014},
  abstract  = {We have used polarized confocal Raman microspectroscopy and scanning near-field optical microscopy with a resolution of 60 nm to characterize photoinscribed grating structures of azobenzene doped polymer films on a glass support. Polarized Raman microscopy allowed determining the reorientation of the chromophores as a function of the grating phase and penetration depth of the inscribing laser in three dimensions. We found periodic patterns, which are not restricted to the surface alone, but appear also well below the surface in the bulk of the material. Near-field optical microscopy with nanoscale resolution revealed lateral two-dimensional optical contrast, which is not observable by atomic force and Raman microscopy.},
  language  = {en}
}
@article{FilimonKopfBalloutetal.2010,
  author    = {Filimon, Marlena and Kopf, Ilona and Ballout, Fuad and Schmidt, Dietrich A. and Bruendermann, Erik and R{\"u}he, J{\"u}rgen and Santer, Svetlana A. and Havenith, Martina},
  title     = {Smart polymer surfaces : mapping chemical landscapes on the nanometre scale},
  issn      = {1744-683X},
  doi       = {10.1039/C0sm00098a},
  year      = {2010},
  abstract  = {We show that Scattering Infrared Near-field Microscopy (SNIM) allows chemical mapping of polymer monolayers that can serve as designed nanostructured surfaces with specific surface chemistry properties on a nm scale. Using s- SNIM a minimum volume of 100 nm x 100 nm x 15 nm is sufficient for a recording of a "chemical'' IR signature which corresponds to an enhancement of at least four orders of magnitudes compared to conventional FT-IR microscopy. We could prove that even in cases where it is essentially difficult to distinguish between distinct polymer compositions based solely on topography, nanophase separated polymers can be clearly distinguished according to their characteristic near-field IR response.},
  language  = {en}
}