Supercritical fluid processing of polymer thin films: An X-ray study of molecular-level porosity

2006 ◽  
Vol 128-130 ◽  
pp. 217-226 ◽  
Author(s):  
Tadanori Koga ◽  
J. Jerome ◽  
M.H. Rafailovich ◽  
B. Chu ◽  
J. Douglas ◽  
...  
Keyword(s):  
Thin Films ◽  
Supercritical Fluid ◽  
Molecular Level ◽  
Polymer Thin Films ◽  
X Ray ◽  
Supercritical Fluid Processing

X-ray reflectometer for study of polymer thin films and interfaces

Vacuum ◽  
1990 ◽  
Vol 41 (4-6) ◽  
pp. 1441-1444 ◽  
Author(s):  
M. Foster ◽  
M. Stamm ◽  
G. Reiter
Keyword(s):  
Thin Films ◽  
Polymer Thin Films ◽  
X Ray

Molecular Level Characterization of Thin Paraffinic Films Using NEXAFS Spectroscopy

1993 ◽  
Vol 307 ◽  
Author(s):  
Paul A. Stevens ◽  
David J. Martella
Keyword(s):  
Thin Films ◽  
Phenyl Ring ◽  
Molecular Level ◽  
Van Der Waals ◽  
Intermolecular Forces ◽  
Native Oxide ◽  
X Ray ◽  
Nexafs Spectroscopy ◽  
Surface Normal ◽  
Repulsive Forces

ABSTRACTBecause near edge X-ray absorption fine structures (NEXAFS) are due to dipole transitions from core levels to unoccupied molecular orbitals, it is an ideal technique for obtaining molecular level information about the orientations of ordered species. Such information is important in assessing the relative importance of various intermolecular forces. For example in long chain molecules with bulky functional groups it is not clear a priori whether the attractive van der Waals forces will overcome the repulsive steric interactions to allow for ordering in thin films. To investigate this we have performed C-K edge NEXAFS spectroscopy studies of thin films of the paraffinic molecules C36H74 and (C18H37)2(NCO)C6H4CO2−+NH2(C18H37)2. The films were grown on a Si(111) surface covered with a native oxide. For the normal alkane, the spectra are dominated by three resolvable (Δhυ≈0.5 eV) features: one (C-H)* peak and two σ*(C-C) peaks. The polarization dependence of these peaks indicates that sub-250 Å C36H74 films have the chains of the molecules aligned along the surface normal. For ≈ 2000 Å films the molecular axes are inclined at angle of 32° with respect to the surface normal, in agreement with the crystalline structure determined by X-ray diffraction. In addition to the major structures of the alkane chains, the C-K NEXAFS of (C18H37)2(NCO)C6H4CO2−+NH2(C18H37)2 has a distinct π* peak due to the phenyl ring. Analysis of these resonances indicates that the C-C chains are also aligned along the surface normal, while the phenyl ring is inclined at an angle of 42° with respect to the normal. In conclusion NEXAFS spectroscopy has been used to show that, for the molecules studied, the attractive van der Waals interactions dominate the repulsive forces thus allowing the molecules to orient with their chains aligned along the surface normal in thin films formed on native oxide covered Si(111).

Supercritical fluid processing of mesoporous crystalline TiO2 thin films for highly efficient dye-sensitized solar cells

2007 ◽  
Vol 17 (37) ◽  
pp. 3888 ◽  
Author(s):  
Mingdeng Wei ◽  
Kaixue Wang ◽  
Masatoshi Yanagida ◽  
Hideki Sugihara ◽  
Michael A. Morris ◽  
...  
Keyword(s):  
Thin Films ◽  
Solar Cells ◽  
Supercritical Fluid ◽  
Dye Sensitized Solar Cells ◽  
Tio2 Thin Films ◽  
Dye Sensitized ◽  
Highly Efficient ◽  
Sensitized Solar Cells ◽  
Supercritical Fluid Processing
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