TY - JOUR A1 - Schrader, Sigurd A1 - Prescher, Dietrich T1 - Fluorine-containing chromophores with special nonlinear optical properties Y1 - 1995 ER - TY - JOUR A1 - Otto, Andreas H. A1 - Prescher, Dietrich A1 - Gey, E. A1 - Schrader, Sigurd T1 - Proton affinities of some polyfluoroalkanes in comparison to the unsubstituted alkanes. The estimation of the proton affinities of polyfluorethylene and polyethylene by applying theoretical methods Y1 - 1997 ER - TY - JOUR A1 - Otto, Andreas H. A1 - Schrader, Sigurd A1 - Steiger, Th. A1 - Schneider, M. T1 - Gas phase deprotonation energies of Sulfuric Acid, Perchloric Acid, Chlorsulfuric Acid and Fluorosulfuric Acid Y1 - 1997 ER - TY - JOUR A1 - Schrader, Sigurd A1 - Schürmann, H. A1 - Druska, P. A1 - Teppner, Randolf A1 - Prescher, Dietrich T1 - Ultraviolet photoelectron spectroscopy of conjugated organic model compounds Y1 - 1997 ER - TY - JOUR A1 - Schrader, Sigurd A1 - Pfeiffer, Karl A1 - Reuther, Freimut A1 - Lorkowski, Hans-Joachim T1 - Stable polymer chromophore systems for nonlinear optics Y1 - 1997 ER - TY - JOUR A1 - Schrader, Sigurd A1 - Prescher, Dietrich T1 - Molecular substitution and nonlinear optical properties of chromophores Y1 - 1997 ER - TY - JOUR A1 - Otto, Andreas H. A1 - Steiger, Th. A1 - Schrader, Sigurd T1 - The gas phase acidity of trifluoromethanesulphonic acid : an ab initio MO and density functional theory study Y1 - 1998 ER - TY - JOUR A1 - Otto, Andreas H. A1 - Steiger, Th. A1 - Schrader, Sigurd T1 - HAICI4 in the gas phase is stronger than HTaF6. Y1 - 1998 ER - TY - JOUR A1 - Schrader, Sigurd A1 - Prescher, Dietrich A1 - Zauls, V. T1 - New chromophores and polymers for second order nonlinear optics Y1 - 1998 ER - TY - JOUR A1 - Schrader, Sigurd A1 - Rieß, Walter A1 - Vestweber, H. A1 - Koch, Norbert T1 - New polymeric heterolayer systems for efficient light-emitting devices Y1 - 1998 ER - TY - JOUR A1 - Schrader, Sigurd A1 - Wortmann, Hanna Rosalie A1 - Prescher, Dietrich A1 - Lukaszuk, K. A1 - Otto, Andreas H. T1 - Solvatochromy and electro-optical study of new fluorine-containing chromophores Y1 - 1998 ER - TY - BOOK A1 - Strehmel, Bernd A1 - Schrader, Sigurd A1 - Seifert, H. ED - Rettig, W. T1 - Applied fluorescence in chemistry, biology and medicine Y1 - 1999 SN - 3-540-64451-2 PB - Springer CY - Berlin ER - TY - JOUR A1 - Schrader, Sigurd A1 - Schürmann, H. A1 - Koch, Norbert A1 - Prescher, Dietrich T1 - Electronic structure of new donor acceptor substituted chromophores Y1 - 1999 ER - TY - JOUR A1 - Schürmann, H. A1 - Koch, Norbert A1 - Vollmer, A. A1 - Schrader, Sigurd A1 - Neumann, M. T1 - Angle resolved ultraviolet photoelectron spectroscopy (ARUPS) of oriented sexiphenyl layers Y1 - 1999 ER - TY - JOUR A1 - Schürmann, H. A1 - Koch, Norbert A1 - Imperia, Paolo A1 - Schrader, Sigurd A1 - Jandke, M. A1 - Strohriegl, P. A1 - Schulz, Burkhard A1 - Leising, G. A1 - Brehmer, Ludwig T1 - Ultraviolet photoelectron spectroscopic study of heterocyclic model compounds for electroluminescent devices Y1 - 1999 ER - TY - JOUR A1 - Schrader, Sigurd A1 - Imperia, Paolo A1 - Koch, Norbert A1 - Leising, G. A1 - Falk, B. T1 - Organic Light-emitting devices based on new heterocyclic compounds Y1 - 1999 ER - TY - JOUR A1 - Schrader, Sigurd A1 - Vismants, Z. A1 - Dietzel, Birgit A1 - Flueraru, C. A1 - Prescher, Dietrich A1 - Reiche, Jürgen A1 - Motschmann, H. A1 - Brehmer, Ludwig T1 - Linear and nonlinear optical properties of Langmuir-Blodgett multilayers from chromophore-containing maleic acid anhydride polymers Y1 - 1999 ER - TY - JOUR A1 - Rossi, L. A1 - Alvarado, Santos F. A1 - Rieß, Walter A1 - Schrader, Sigurd A1 - Lidzey, D. G. A1 - Bradley, D. D. C. T1 - Influence of alkoxy substituents on the exciton binding energy of conjugated polymers Y1 - 2000 ER - TY - JOUR A1 - Fazio, V. S. U. A1 - Lagerwall, S. T. A1 - Zauls, V. A1 - Schrader, Sigurd A1 - Busson, P. A1 - Hult, A. A1 - Motschmann, H. T1 - Nonlinear optical properties of a channel waveguide produced with crosslinkable ferroelectric liquid crystals Y1 - 2000 ER - TY - JOUR A1 - Flueraru, C. A1 - Schrader, Sigurd A1 - Zauls, V. A1 - Motschmann, H. T1 - Sensitivity analysis of ellipsometry applied to uniaxial optical films Y1 - 2000 ER - TY - JOUR A1 - Stephan, Jörg A1 - Schrader, Sigurd A1 - Brehmer, Ludwig T1 - Monte Carlo simulations of charge transport in molecular solids : a modified Miller Abrahams type jump rate approach Y1 - 2000 ER - TY - JOUR A1 - Möller, Gunter Eric A1 - Schrader, Sigurd A1 - Motschmann, H. A1 - Prescher, Dietrich T1 - Influence of a base electrolyte on the adsorption behavior of an anionic surfactant as observed by second harmonic generation Y1 - 2000 ER - TY - JOUR A1 - Schürmann, H. A1 - Koch, Norbert A1 - Vollmer, A. A1 - Schrader, Sigurd A1 - Neumann, M. T1 - Angle resolved ultraviolet photoelectron spectroscopy of oriented sexiphenyl layers Y1 - 2000 ER - TY - THES A1 - Schrader, Sigurd T1 - Elektronische Struktur und Anregungsprozesse orgainscher Halbleiter Y1 - 2003 ER - TY - JOUR A1 - Nagy, A. A1 - Strahl, A. A1 - Neuhauser, H. A1 - Schrader, Sigurd A1 - Behrens, I. A1 - Peiner, E. A1 - Schlachetzki, A. T1 - Mechanical spectroscopy of thin layers of PPV polymer on Si substrates N2 - The vibrating reed technique with electro "static" excitation and optical detection has been applied to investigate thin layers of poly-phenylene-vinylene, deposited by spin coating onto microfabricated Si cantilevers, during temperature cycling programs between 90 and 540 K at a rate of 1 K/min. From the vibration frequencies the Young's modulus of the film can be estimated to be about 10 MPa at room temperature in the precursor phase (if prepared from a solution in toluene), which increases by conversion to the conjugate bonded polymer to about 50 MPa. The temperature dependence of internal friction reveals the processes of gamma relaxations (crankshaft motion of side branches in the precursor) and P-relaxation (movements of a few monomer blocks in the polymer chain), as well as peaks indicating the structural transformations during conversion, and possibly a glass transition in the amorphous precursor phase. After conversion only the P-relaxation persists. (C) 2003 Elsevier B.V. All rights reserved Y1 - 2004 SN - 0921-5093 ER - TY - JOUR A1 - Schrader, Sigurd A1 - Penzkofer, Alfons A1 - Holzer, W. A1 - Velagapudi, Ramakrishna A1 - Grimm, Bernhard T1 - Laser spectroscopic investigation of a new precursor - type polyparaphenylenevinylene N2 - Optical, structural and morphological properties of thin films of polyparaphenylenevinylene (PPV) formed by an alkyl sulfinyl precursor route have been studied. Thin films were fabricated on an optical glass and on quartz glass either by spin-coating of the precursor solution or by layer-by-layer deposition using Langmuir-Blodgett technique. PPV precursor films were also spin-coated on gold-coated glass in order to study thin-film optical parameters by surface plasmon spectroscopy. We have been successful in forming about 40 precursor mono layers on quartz glass by Langmuir- Blodgett technique using optimized surface pressure and dipping conditions. After thermal conversion of the precursor layers good quality fluorescent PPV films of yellow colour have been obtained. Optical characterization of the films was carried out by linear absorption and emission spectroscopy, ellipsometry, and surface plasmon spectroscopy. Structural and morphological studies on the thin films were carried out by using X-ray scattering and atomic force microscopy. Wave- guided travelling-wave laser action has been achieved in a PPV film on quartz glass. The sample was transversally pumped with picosecond laser pulses (wavelength 347.15 nm, duration 35 ps). Laser emission occurred at 550 nm for pump pulse energy densities above 1 x 10(-4) J cm(-2). (C) 2004 Elsevier B.V. All rights reserved Y1 - 2004 SN - 0022-2313 ER - TY - JOUR A1 - Smertenko, P. S. A1 - Dimitriev, O. P. A1 - Schrader, Sigurd A1 - Brehmer, Ludwig T1 - Doping of polyaniline by transition metal salts : current-voltage characteristics of the ITO/polymer film/metal heterostructures N2 - Films of emeraldine base of polyaniline (PAni) doped by various transition metal salts have been prepared, and current-voltage characteristics of the indium-tin oxide (ITO)/PAni film/metal electrode heterostructures were investigated. It was found that the electrical characteristics of the heterostructures are greatly affected by the dopant used and the metal electrode used. Different dopants resulted in different current anomalies with asymmetric current-voltage characteristics. Depending on the dopant used, the exponential and power law of the current behavior can be distinguished. Depending on the metal electrode used, two different regimes of current passing have been found at low applied voltages, namely, a nearly ohmic regime for the indium electrode, and a diode regime for the aluminum electrode. The diode regime was found to accompany by a positive charge accumulation in the film near the film/metal interface, which creates a built-in potential in the film. The amount of positive charges accumulated at the interface and therefore the value of the built-in potential can be reversibly increased or reduced by successive runs of the applied voltage in the forward or reverse direction, respectively. (C) 2004 Elsevier B.V. All rights reserved Y1 - 2004 SN - 0379-6779 ER - TY - JOUR A1 - Breu, J. A1 - Stossel, P. A1 - Schrader, Sigurd A1 - Starukhin, A. A1 - Finkenzeller, W. J. A1 - Yersin, H. T1 - Crystal structure of fac-Ir(ppy)(3) and emission properties under ambient conditions and at high pressure N2 - Solution and refinement of the crystal structure of fac-Ir(ppy)(3) is severely hampered by systematic twinning and pseudo-symmetry.fac-Ir(ppy)(3) Crystallizes in the centrosymmetric space group P (3) over bar as has been deduced from single-crystal structure refinement and investigations of the second harmonic generation (SHG) of fac-Ir(ppy)(3) powder as compared to two standard materials. The topology of the molecular packing of fac-Ir(ppy)(3) is identical to the packing observed for [Ru(bpy)(3)](0), however, the site symmetry of all Ir(ppy)(3) molecules is necessarily lowered from D-3 to C-3. Packing motifs with intermolecular "pi-pi interactions" of T-shaped and "shifted pi stack" geometry are realized. The systematic twinning leads to the occurrence of crystalline domains with rigorously alternating chirality within the bulk of the domains but with homochiral fac-Ir(ppy)(3) contacts at the domain interfaces. These differences in packing motifs are displayed in the emission spectra and in the high-pressure-induced shifts of the emission. The emission maximum of the bulk material at 18 350 cm(-1) (545 nm) and of the domain interfaces at 19 700 cm-1 (507 nm) experience for p < 25 kbar and T = 295 K red shifts of Delta nu/Delta p = -(12 +/- 2) cm(-1)/kbar, and -(22 +/- 4) cm(- 1)/kbar, respectively Y1 - 2005 SN - 0897-4756 ER - TY - JOUR A1 - Holzer, Wolfgang A1 - Penzkofer, Alfons A1 - Schrader, Sigurd A1 - Grimm, Bernhard T1 - Photo-physical and lasing characterisation of a polyparaphenylenevinylene (PPV) neat film N2 - The wave-guided travelling-wave laser action (amplified spontaneous emission) of a neat film of poly(p- phenylenevinylene) (PPV) on a quartz glass substrate prepared by a sulfinyl precursor technique is studied. The samples are transversally pumped with picosecond excitation pulses (wavelength 347.15 nm, duration 35 ps). Lasing occurs at 550 nm. The optical constants of the neat films are determined by transmittance measurements exploiting the multiple beam interference in the transparency region. A fluorescence spectroscopic characterisation is carried out determining the fluorescence quantum distribution, fluorescence quantum yield, degree of fluorescence polarisation, and fluorescence lifetime. The emitting chromophore size (emitting singlet exciton extension) is determined by the ratio of exciton radiative lifetime to repeat-unit based radiative lifetime. The obtained size of about two repeat units is discussed in a disordered solid-state polymer model Y1 - 2005 SN - 0306-8919 ER - TY - BOOK A1 - Smertenko, P. A1 - Fenenko, L. A1 - Brehmer, Ludwig A1 - Schrader, Sigurd T1 - Differential approach to the study of integral characteristics in polymer films N2 - The differential approach is based on the determination of dimensionless differential slope, for instance, of current-voltage characteristics (IVC), I=f(V). This slope (a) is given by formula alpha=d(lgI)/d(lgV). With such definition the ranges of constancy of the a(V) dependency correspond to the part of IVC characterized by the power behaviour (I similar to V-alpha). The differential slope of alpha(V) dependency gamma = d(lg alpha)/dlgV determines the exponent behaviour of curve (I similar to exp {eV(y)/kT}). Processing by the differential approach of the investigated theoretical or experimental characteristics permits us to determine the peculiarity of charge flow mechanisms, temperature behaviour of conductivity, etc. The theoretical base and some applications of differential approach to the investigation of the current-voltage, temperature and degradation characteristics of the polyaniline and poly(p- phenilenevinilene) based structures have been shown. (c) 2005 Elsevier B.V. All rights reserved Y1 - 2005 ER - TY - JOUR A1 - Wong, J. E. A1 - Detert, H. A1 - Brehmer, Ludwig A1 - Schrader, Sigurd T1 - Green light-emitting devices based on soluble oligo(phenylenevinylenes) N2 - In this work, we report our investigations on the film-forming properties as well as the optical and electroluminescent characterisations of a series of lateral-substituted soluble oligo(phenylenevinylenes) of various conjugation length. Preliminary investigations show that these materials are potential candidates for use in organic light-emitting devices (OLEDs). Two types of OLEDs were fabricated: single layer (SL) and single heterostructure (SHS), with poly(p-phenylenevinylene) (PPV) as hole transporting layer. Our best results were obtained with single layer device emitting green light with a luminance of 0.18 cd m(-2) and 0.24 cd m(-2) at a driving voltage of 10 V. (c) 2004 Elsevier B.V. All rights reserved Y1 - 2005 SN - 0169-4332 ER -