@article{WeberFrankBommeletal.2012,
  author    = {Weber, Cornelia and Frank, C. and Bommel, Sebastian and Rukat, Tammo and Leitenberger, Wolfram and Sch{\"a}fer, Peter and Schreiber, Frank and Kowarik, Stefan},
  title     = {Chain-length dependent growth dynamics of n-alkanes on silica investigated by energy-dispersive x-ray reflectivity in situ and in real-time},
  series = {The journal of chemical physics : bridges a gap between journals of physics and journals of chemistr},
  volume    = {136},
  journal   = {The journal of chemical physics : bridges a gap between journals of physics and journals of chemistr},
  number    = {20},
  publisher = {American Institute of Physics},
  address   = {Melville},
  issn      = {0021-9606},
  doi       = {10.1063/1.4719530},
  pages     = {7},
  year      = {2012},
  abstract  = {We compare the growth dynamics of the three n-alkanes C36H74, C40H82, and C44H90 on SiO2 using real-time and in situ energy-dispersive x-ray reflectivity. All molecules investigated align in an upright-standing orientation on the substrate and exhibit a transition from layer-by-layer growth to island growth after about 4 monolayers under the conditions employed. Simultaneous fits of the reflected intensity at five distinct points in reciprocal space show that films formed by longer n-alkanes roughen faster during growth. This behavior can be explained by a chain-length dependent height of the Ehrlich-Schwoebel barrier. Further x-ray diffraction measurements after growth indicate that films consisting of longer n-alkanes also incorporate more lying-down molecules in the top region. While the results reveal behavior typical for chain-like molecules, the findings can also be useful for the optimization of organic field effect transistors where smooth interlayers of n-alkanes without coexistence of two or more molecular orientations are required.},
  language  = {en}
}
@article{KowarikGerlachLeitenbergeretal.2007,
  author    = {Kowarik, Stefan and Gerlach, Andreas and Leitenberger, Wolfram and Hu J, Witte and W{\"o}ll, Christoph and Schreiber, Frank},
  title     = {Energy-dispersive X-ray reflectivity and GID for real-time growth studies of pentacene thin films},
  issn      = {0040-6090},
  doi       = {10.1016/j.tsf.2006.12.020},
  year      = {2007},
  abstract  = {We use energy-dispersive X-ray reflectivity and grazing incidence diffraction (GID) to follow the growth of the crystalline organic semiconductor pentacene on silicon oxide in-situ and in real-time. The technique allows for monitoring Bragg reflections and measuring X-ray growth oscillations with a time resolution of 1 min in a wide q-range in reciprocal space extending over 0.25-0.80 angstrom(-1), i.e. sampling a large number of Fourier components simultaneously. A quantitative analysis of growth oscillations at several q-points yields the evolution of the surface roughness, showing a marked transition from layer-by-layer growth to strong roughening after four monolayers of pentacene have been deposited. (c) 2006 Elsevier B.V. All rights reserved.},
  language  = {en}
}
@article{LiehrJaegerKarapanagiotisetal.2019,
  author    = {Liehr, Sascha and J{\"a}ger, Lena Ann and Karapanagiotis, Christos and Munzenberger, Sven and Kowarik, Stefan},
  title     = {Real-time dynamic strain sensing in optical fibers using artificial neural networks},
  series = {Optics express : the international electronic journal of optics},
  volume    = {27},
  journal   = {Optics express : the international electronic journal of optics},
  number    = {5},
  publisher = {Optical Society of America},
  address   = {Washington},
  issn      = {1094-4087},
  doi       = {10.1364/OE.27.007405},
  pages     = {7405 -- 7425},
  year      = {2019},
  abstract  = {We propose to use artificial neural networks (ANNs) for raw measurement data interpolation and signal shift computation and to demonstrate advantages for wavelength-scanning coherent optical time domain reflectometry (WS-COTDR) and dynamic strain distribution measurement along optical fibers. The ANNs are trained with synthetic data to predict signal shifts from wavelength scans. Domain adaptation to measurement data is achieved, and standard correlation algorithms are outperformed. First and foremost, the ANN reduces the data analysis time by more than two orders of magnitude, making it possible for the first time to predict strain in real-time applications using the WS-COTDR approach. Further, strain noise and linearity of the sensor response are improved, resulting in more accurate measurements. ANNs also perform better for low signal-to-noise measurement data, for a reduced length of correlation input (i.e., extended distance range), and for coarser sampling settings (i.e., extended strain scanning range). The general applicability is demonstrated for distributed measurement of ground movement along a dark fiber in a telecom cable. The presented ANN-based techniques can be employed to improve the performance of a wide range of correlation or interpolation problems in fiber sensing data analysis and beyond. (C) 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement},
  language  = {en}
}
@article{LangeReiterPaetzeletal.2014,
  author    = {Lange, Ilja and Reiter, Sina and Paetzel, Michael and Zykov, Anton and Nefedov, Alexei and Hildebrandt, Jana and Hecht, Stefan and Kowarik, Stefan and Woell, Christof and Heimel, Georg and Neher, Dieter},
  title     = {Tuning the work function of polar zinc oxide surfaces using modified phosphonic acid self-assembled monolayers},
  series = {Advanced functional materials},
  volume    = {24},
  journal   = {Advanced functional materials},
  number    = {44},
  publisher = {Wiley-VCH},
  address   = {Weinheim},
  issn      = {1616-301X},
  doi       = {10.1002/adfm.201401493},
  pages     = {7014 -- 7024},
  year      = {2014},
  abstract  = {Zinc oxide (ZnO) is regarded as a promising alternative material for transparent conductive electrodes in optoelectronic devices. However, ZnO suffers from poor chemical stability. ZnO also has a moderate work function (WF), which results in substantial charge injection barriers into common (organic) semiconductors that constitute the active layer in a device. Controlling and tuning the ZnO WF is therefore necessary but challenging. Here, a variety of phosphonic acid based self-assembled monolayers (SAMs) deposited on ZnO surfaces are investigated. It is demonstrated that they allow the tuning the WF over a wide range of more than 1.5 eV, thus enabling the use of ZnO as both the hole-injecting and electron-injecting contact. The modified ZnO surfaces are characterized using a number of complementary techniques, demonstrating that the preparation protocol yields dense, well-defined molecular monolayers.},
  language  = {en}
}