TY  - JOUR
A1  - Pietsch, Ullrich
A1  - Bodenthin, Yves
A1  - Grenzer, Jörg
A1  - Geue, Thomas
A1  - Möhwald, Helmuth
A1  - Kurth, Dirk G.
T1  - Structure and temperature behavior of metallo-supramolecular assemblies
N2  - A detailed structural analysis of a Langmuir-Blodgett (LB) multilayer composed of a polyelectrolyte-amphiphile complex (PAC) is presented. The PAC is self-assembled from metal ions, ditopic bis-terpyridines, and amphiphiles. The vertical structure of the LB multilayer is investigated by X-ray reflectometry. The multilayer has a periodicity of 57 A, which corresponds to an architecture of flat lying metallo-supramolecular coordination polyelectrolyte (MEPE) rods and upright-standing amphiphiles (dihexadecyl phosphate, DHP). In-plane diffraction reveals hexagonal packing of the DHP molecules. Using extended X-ray absorption fine structure (EXAFS) experiments, we prove that the central metal ion is coordinated to the terpyridine moieties in a pseudo-octahedral coordination environment. The Fe-N bond distances are 1.82 and 2.0 angstrom, respectively. Temperature resolved measurements indicate a reversible phase transition in a temperature range up to 55 degrees C. EXAFS measurements indicate a lengthening of the average Fe-N bond distance from 1.91 to 1.95 angstrom. The widening of the coordination cage upon heating is expected to lower the ligand field stabilization, thus giving rise to spin transitions in these composite materials
Y1  - 2005
ER  - 
TY  - JOUR
A1  - Pietsch, Ullrich
A1  - Mukhopadhyay, M. K.
A1  - Sanyal, M. K.
A1  - Datta, A.
A1  - Mukherjee, M.
A1  - Geue, Thomas
A1  - Grenzer, Jörg
T1  - Transition from two-dimensional to three-dimensional melting in Langmuir-Blodgett films
N2  - Results of energy-dispersive x-ray reflectivity and grazing incidence diffraction studies of Langmuir-Blodgett films exhibited evolution of conventional three-dimensional melting from continuous melting, characteristic of two- dimensional systems, as a function of deposited monolayers. Continuous expansion followed by a sharp phase transition of the in-plane lattice was observed before the melting point and found to be independent of number of deposited layers. Evolution of conventional melting with an increase in the number of monolayers could be quantified by measuring stiffness against tilting of the vertical stack of molecules, which are kept together by an internal field. The internal field as defined in this model reduces as the in-plane lattice expands and the sample temperature approaches melting point. The sharpness of the melting transition, which has been approximated by a Langevin function, increases with the number of deposited monolayers
Y1  - 2004
ER  - 
TY  - JOUR
A1  - Pietsch, Ullrich
A1  - Panzner, Tobias
A1  - Leitenberger, Wolfram
A1  - Grenzer, Jörg
A1  - Bodenthin, Th.
A1  - Geue, Thomas
A1  - Möhwald, Helmuth
T1  - Coherence experiments at the energy-dispersive reflectometry beamline at BESSY II
Y1  - 2003
ER  - 
TY  - JOUR
A1  - Pietsch, Ullrich
A1  - Bhattacharya, M. K.
A1  - Mukherjee, M.
A1  - Sanyal, M. K.
A1  - Geue, Thomas
A1  - Grenzer, Jörg
T1  - Energy dispersive x-ray reflectivity technique to study thermal properties of polymer films
Y1  - 2003
ER  - 
TY  - JOUR
A1  - Geue, Thomas
A1  - Henneberg, Oliver
A1  - Grenzer, Jörg
A1  - Pietsch, Ullrich
A1  - Natansohn, Almeria
A1  - Rochon, Paul
A1  - Finkelstein, Kenneth D.
T1  - Formation of a buried density grating on thermal erasure of azobenzene polymer surface gratings
Y1  - 2002
SN  - 0927-7757
ER  - 
TY  - JOUR
A1  - Pietsch, Ullrich
A1  - Grenzer, Jörg
A1  - Geue, Thomas
A1  - Neißendorfer, Frank
A1  - Brezesinski, Gerald
A1  - Symietz, Christian
A1  - Möhwald, Helmuth
A1  - Gudat, Wolfgang
T1  - The energy dispersive reflectometer at BESSY II : a challenge for thin film analysis
Y1  - 2001
SN  - 0167- 5087
ER  - 
TY  - JOUR
A1  - Grenzer, Jörg
A1  - Darowski, Nora
A1  - Geue, Thomas
A1  - Pietsch, Ullrich
A1  - Daniel, A.
A1  - Rennon, Siegfried
A1  - Reithmaier, Johann-Peter
A1  - Forchel, Alfred
T1  - Strain analysis and quantum well intermixing of a laterally modulated multiquantum well system produced by focused ion beam implantation
Y1  - 2001
ER  - 
TY  - JOUR
A1  - Stahn, Jochen
A1  - Geue, Thomas
A1  - Grenzer, Jörg
A1  - Pietsch, Ullrich
T1  - Interaction of short-chain alkanes with surface and interfaces of multilayer films built from amphiphilic molecules: an in-situ X-ray and neutron scattering probe
Y1  - 2000
ER  - 
TY  - JOUR
A1  - Karcenko, Anatolij V.
A1  - Englisch, Uwe
A1  - Grenzer, Jörg
A1  - Geue, Thomas
A1  - Pietsch, Ullrich
A1  - Siebrecht, R.
T1  - Investigation of partially deuterated multilayers by means of X-ray and polarized neutron reflectometry
Y1  - 2000
SN  - 1044-8632
ER  - 
TY  - JOUR
A1  - Mukherjee, M.
A1  - Bhattacharya, M. K.
A1  - Sanyal, M. K.
A1  - Geue, Thomas
A1  - Grenzer, Jörg
A1  - Pietsch, Ullrich
T1  - Temperature dependent thickness and surface tension of polymer films
Y1  - 2000
SN  - 81-7371295-6
ER  -