@misc{HoffmannMikaloYfantisetal., author = {Hoffmann, Patrick and Mikalo, Ricardo Pablo and Yfantis, Alexandros D. and Batchelor, David R. and Appel, G{\"u}nter and Schmeißer, Dieter}, title = {A Spectro-Microscopic Approach for Thin Film Analysis Grain Boundaries in mc-Si and Sn/SnO2 Nano Particles}, series = {Microchimica Acta}, volume = {136}, journal = {Microchimica Acta}, number = {3-4}, issn = {1436-5073}, pages = {109 -- 113}, language = {en} } @inproceedings{MikaloAppelHoffmannetal., author = {Mikalo, Ricardo Pablo and Appel, G{\"u}nter and Hoffmann, Patrick and Schmeißer, Dieter}, title = {Conducting Polypyrrole doped with Phthalocyaninesulfonates - new materials for chemical sensors}, series = {Verhandlungen der Deutschen Physikalischen Gesellschaft}, booktitle = {Verhandlungen der Deutschen Physikalischen Gesellschaft}, publisher = {Deutsche Physikalische Gesellschaft}, address = {Bad Honnef}, abstract = {Polypyrrole - a conducting polymer - is used as an active electrode of a quartz micro ballance and considered as a gate electrode in all-polymer field effect transistors used as chemical sensor. We use substituted phthalocyanines as dopants of polypyrrole as they offer the possibility to enhance the dopant concentration as well as to include functionalized groups. We studied these films by photoelectron spectroscopy, NEXAFS, PEEM, and TEM. These investigations revealed that the electronic structure as well as the morphology are highly dependent on the dopant's structure. We suggest a new charge transport model for 5-ring heterocycle conductive polymers. Whereas in the standard model only the carbon backbone is considered for the charge transport, we found by NEXAFS investigations that the heteroatom has a considerable high participation in the gap states, which are responsible for the charge transport. The dopants π-interactions force the nitrogen lone pair wave functions to contribute to the conducting polymer π-system. This is a novel approach concerning the application as chemical sensors since the reversible interaction of the analyte modifies the dopant and not the matrix.}, language = {en} } @inproceedings{MikaloAppelHoffmannetal., author = {Mikalo, Ricardo Pablo and Appel, G{\"u}nter and Hoffmann, Patrick and Schmeißer, Dieter}, title = {Leitf{\"a}higes Polypyrrol als Elektrodenmaterial: Wechselwirkungen mit Silber}, series = {Verhandlungen der Deutschen Physikalischen Gesellschaft}, booktitle = {Verhandlungen der Deutschen Physikalischen Gesellschaft}, publisher = {Deutsche Physikalische Gesellschaft}, address = {Bad Honnef}, abstract = {Untersuchungen des metallischen Kontaktes von Silber auf tosylat- und phthalocyanindotiertem Polypyrrol wurden mittels XPS- und µ-NEXAFS vorgenommen. Es wurde festgestellt, daß Silber mit dem Polypyrrol keine Verbindung eingeht. Daraus kann geschlossen werden, daß sowohl das leitf{\"a}hige Polymer, als auch das Silber ihren Leitf{\"a}higkeitsmechanismus beibehalten. Es konnte gezeigt werden, daß bei steigender Silberbelegung die Intensit{\"a}t der Polaronenzust{\"a}nde des Polypyrrol in st{\"a}rkerem Maße abnimmt, als die Intensit{\"a}t der unbesetzten Zust{\"a}nde. Das l{\"a}ßt darauf schließen, daß Silber die Grenzfl{\"a}che stabilisiert.}, language = {de} } @misc{HenkelOpreaPaloumpaetal., author = {Henkel, Karsten and Oprea, A. and Paloumpa, Ioanna and Appel, G{\"u}nter and Schmeißer, Dieter and Kamieth, P.}, title = {Selective polypyrrole electrodes for quartz microbalances : NO2 and gas flux sensitivities}, series = {Sensors and Actuators : B, Chemical 76(2001)1-3}, volume = {76}, journal = {Sensors and Actuators : B, Chemical 76(2001)1-3}, number = {1-3}, issn = {0925-4005}, pages = {124 -- 129}, language = {en} } @techreport{HenkelPaloumpaOpreaetal., author = {Henkel, Karsten and Paloumpa, Ioanna and Oprea, A. and Appel, G{\"u}nter and Schmeißer, Dieter and Frandsen, W. and Sch{\"o}lzel, Mario}, title = {Entwicklung von Sensoren mit Elektroden aus leitf{\"a}higen Polymeren}, language = {de} } @article{AppelSchmeisserBaueretal., author = {Appel, G{\"u}nter and Schmeißer, Dieter and Bauer, Jakob and Bauer, Monika and Egelhaaf, H. J. and Oelkrug, D.}, title = {The formation of oligomers in the electrolyte upon polymerization of pyrrole}, language = {en} } @article{YfantisAppelSchmeisseretal., author = {Yfantis, Alexandros D. and Appel, G{\"u}nter and Schmeißer, Dieter and Yfantis, Alexandros D.}, title = {Polypyrrole doped with fluoro-metal complexes: thermal stability and structural properties}, language = {en} } @phdthesis{Appel, author = {Appel, G{\"u}nter}, title = {Untersuchungen zur mesoskopischen und elektronischen Struktur von Polypyrroltosylat und Polypyrrolkupferphthalocyaninsulfonat}, publisher = {Shaker}, address = {Aachen}, isbn = {3-8265-4830-2}, pages = {118}, language = {de} } @article{AppelBoehmeSchmeisser, author = {Appel, G{\"u}nter and B{\"o}hme, O. and Schmeißer, Dieter}, title = {NEXAFS-Spectroscopy of Differently Doped Polypyrroles}, language = {en} } @misc{GuerekAppelMikaloetal., author = {G{\"u}rek, A. G. and Appel, G{\"u}nter and Mikalo, Ricardo Pablo and Schmeißer, Dieter}, title = {Synthesis of dihydroxy silicon phthalocyanine tetrasulfonic acid and poly-µ-oxo silicon phthalocyanine tetrasulfonic acid}, series = {Journal of Porphyrins and Phthalocyanines}, volume = {5}, journal = {Journal of Porphyrins and Phthalocyanines}, number = {10}, issn = {1099-1409}, pages = {751 -- 757}, language = {en} } @article{MikaloAppelHoffmannetal., author = {Mikalo, Ricardo Pablo and Appel, G{\"u}nter and Hoffmann, Patrick and Schmeißer, Dieter}, title = {Band Bending in Doped Conducting Polypyrrole Interaction with Silver}, language = {en} } @article{MikaloAppelSchmeisser, author = {Mikalo, Ricardo Pablo and Appel, G{\"u}nter and Schmeißer, Dieter}, title = {Conductivity of Silver exposed Polypyrrole Films}, language = {en} } @article{MikaloAppelHoffmannetal., author = {Mikalo, Ricardo Pablo and Appel, G{\"u}nter and Hoffmann, Patrick and Schmeißer, Dieter and Mast, M.}, title = {Multi-Atom Resonant Photoemission applied to study the silver to nitrogen interaction in polypyrrole films}, language = {en} } @article{SchmeisserAppelBoehmeetal., author = {Schmeißer, Dieter and Appel, G{\"u}nter and B{\"o}hme, O. and Heller, Thomas and Mikalo, Ricardo Pablo and Hoffmann, Patrick and Batchelor, David R.}, title = {Nanoparticles and polarons: active centers in thin film sensor devices}, language = {de} } @article{MikaloHoffmannHelleretal., author = {Mikalo, Ricardo Pablo and Hoffmann, Patrick and Heller, Thomas and Batchelor, David R. and Appel, G{\"u}nter and Schmeißer, Dieter}, title = {Doping and defect inhomogeneities of polypyrrole tosylate films as revealed by ?-NEXAFS}, language = {en} } @article{OpreaHenkelOehmgenetal., author = {Oprea, A. and Henkel, Karsten and Oehmgen, R. and Appel, G{\"u}nter and Schmeißer, Dieter and Lauer, H. and Hausmann, P.}, title = {Increased sensor sensitivities obtained by polymer coated quartz microbalances}, language = {en} } @article{AppelYfantisGoepeletal., author = {Appel, G{\"u}nter and Yfantis, Alexandros D. and G{\"o}pel, W. and Schmeißer, Dieter}, title = {Highly conductive polypyrrole films on nonconductive substrates}, language = {en} } @misc{AppelAdeGuereketal., author = {Appel, G{\"u}nter and Ade, H. and G{\"u}rek, A. G. and Stadler, S. and Mikalo, Ricardo Pablo and Schmeißer, Dieter}, title = {Orientation studies of Si-Phthalocyanines sulfonic acids cast on SiOx substrates}, series = {Applied Physics / A}, volume = {76}, journal = {Applied Physics / A}, number = {2}, issn = {1432-0630}, doi = {10.1007/s003390201320}, pages = {177 -- 182}, abstract = {Layers of dihydroxy silicon phthalocyanine tetrasulfonic acid and oligo-7-oxo silicon phthalocyanine tetrasulfonic acid were prepared by solution-casting methods. The purity of the material was checked by X-ray photoemission spectroscopy. The orientation of the molecules in respect to the substrate plane was investigated by angle-dependent near-edge X-ray absorption fine-structure spectroscopy. The morphology was characterized by atomic force microscopy. Most samples exhibited a significant orientation that was accompanied by crystalline structures; others had no orientation at all with a dominant amorphous morphology. This behavior indicates that several preparation parameters affect the crystallinity and the orientation of the phthalocyanines.}, language = {en} } @article{AppelMikaloHenkeletal., author = {Appel, G{\"u}nter and Mikalo, Ricardo Pablo and Henkel, Karsten and Oprea, A. and Yfantis, Alexandros D. and Paloumpa, Ioanna and Schmeißer, Dieter}, title = {Polymeric Electrodes}, language = {en} } @article{MikaloAppelHoffmannetal., author = {Mikalo, Ricardo Pablo and Appel, G{\"u}nter and Hoffmann, Patrick and Schmeißer, Dieter}, title = {Determination of the Vacuum Level in NEXAFS-spectra by Selected-Yield-NEXAFS}, language = {en} } @article{AppelBoehmeMikaloetal., author = {Appel, G{\"u}nter and B{\"o}hme, O. and Mikalo, Ricardo Pablo and Schmeißer, Dieter}, title = {The polaron and bipolaron contributions to the electronic structure of polypyrrole films}, language = {en} }