Zeitschriftenaufsätze

Maaß, Philipp; Peibst, Robby
Ion diffusion and mechanical losses in mixed alkali glasses. - In: Journal of non-crystalline solids, ISSN 0022-3093, Bd. 352 (2006), 42/49, S. 5178-5187

Based on general theoretical considerations we show that the fraction cV of vacant sites for the mobile ions in glasses should be small in order to understand the peculiar behavior of the internal friction in the mixed alkali effect. Moreover, for small cV, the steep fall of the conductivity in the dilute foreign alkali region can be explained by a trapping of vacancies induced by the minority ions. To demonstrate our general analysis we study a simple hopping model and show that it allows one to recover both the typical behavior of the internal friction (shifts of single and mixed alkali peak positions with the mixing ratio and associated changes in activation energies, changes of peak heights) and the typical behavior of tracer diffusion coefficients (drastic fall of mobility of one type of ion by replacement with a second type of mobile ion and associated changes in activation energies). Reasonable values of model parameters can be estimated from measured data and predictions are made for experiments.

http://dx.doi.org/10.1016/j.jnoncrysol.2005.12.061

Ashraf, Raja Shahid; Hoppe, Harald; Shahid, Munazza; Gobsch, Gerhard; Sensfuss, Steffi; Klemm, Elisabeth
Synthesis and properties of fluorene-based polyheteroarylenes for photovoltaic devices. - In: Journal of polymer science, ISSN 1099-0518, Bd. 44 (2006), 24, S. 6952-6961

https://doi.org/10.1002/pola.21645

Shokhovets, Sviatoslav; Gobsch, Gerhard; Ambacher, Oliver
Excitonic contribution to the optical absorption in zinc-blende III-V semiconductors. - In: Physical review. Condensed matter and materials physics / American Physical Society. - College Park, Md. : APS, 1970-2015 , ISSN: 1550-235X , ZDB-ID: 1473011-X, ISSN 1550-235X, Bd. 74 (2006), 15, S. 155209, insges. 11 S.

http://dx.doi.org/10.1103/PhysRevB.74.155209

Westenhoff, Sebastian; Beenken, Wichard J. D.; Yartsev, Arkady; Greenham, Neil C.
Conformational disorder of conjugated polymers. - In: The journal of chemical physics, ISSN 1089-7690, Bd. 125 (2006), 15, 154903, insges. 7 S.

Conformational disorder of conjugated polymers is an important issue to be understood and quantified. In this paper we present a new method to assess the chain conformation of conjugated polymers based on measurements of intrachain energy transfer. The chain conformation is modeled on the basis of monomer-monomer interactions, such as torsion, bending, and stretching of the connecting bond. The latter two potentials are assumed to be harmonic, while the torsional potential was calculated by density functional theory using B3-LYP functional with the SVP basis set. The energy transfer dynamics of excitons on these chains are quantitatively simulated using Förster-type line-dipole energy transfer. This allows us to compare the simulated ground state conformation of single polymer chains to ultrafast depolarization experiments of poly [3-(2,5-dioctylphenyl)thiophene] in solution. We identify torsional rotation as the main contributor to conformational disorder and find that this disorder is mainly controlled by the energy difference between syn and anti bonds.

https://doi.org/10.1063/1.2358682

Liu, Yonghe; Schäfer, Jürgen A.; Jäger, Gerd
Materials, bearings, and lubricants for nanopositioning. - In: Technisches Messen, ISSN 2196-7113, Bd. 73 (2006), 9, S. 500-510

http://dx.doi.org/10.1524/teme.2006.73.9.500