Photoinduced structural relaxation and densification in sol-gel-derived nanocomposite thin films: implications for integrated optics device fabrication
Article Abstract:
Photoinduced structural densification and relaxation in sol-gel-derived nanocomposite thin films have been studied. The solution sol-gel method was used to put thin films of photosensitive hybrid organic-inorganic glass on silicon. The resulting films were clear, low-optical-loss ones, an indication of nanophase homogeneity in samples. Changes in refractive index are related to collateral densification. That leads to compaction of the silicate network in organic free-radical polymerization with unreacted methoxysilane and free silanol used up in the process. There are related implications for making integrated optics devices. The ways in which integrated optics devices, Bragg gratings and ridge wave guides, for instance, are inscribed by photolithography in hybrid sol-gel silica glass films rich in acrylates on silicon are now better understood. It takes almost twice as much photon energy to densify sol-gel silica without an organic component.
Publication Name: Canadian Journal of Chemistry
Subject: Chemistry
ISSN: 0008-4042
Year: 1998
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Three-dimensional magnetic resonance imaging of rigid polymeric materials using single-point ramped imaging with T1 enhancement (SPRITE)
Article Abstract:
Three-dimensional (3-D) magnetic resonance imaging (MRI) of rigid polymeric materials has been carried out using single-point ramped imaging with T1 enhancement (SPRITE). The goal was to investigate what advantages might be found in the use of the SPRITE technique vs conventional imaging methods.. SPRITE is a new MRI method for imaging rigid polymeric materials and is intended for spatially encoding short-lifetime signals found with rigid materials. A 2D SPRITE image of four common polymers was compared to a 2D spin-echo image. 3-D images of millimeter resolution show internal physical differentiation and chemical inhomogeneities that are not seen with the other methods. Incorporation of active spoiler gradients in SPRITE for looking at samples with long spin-spin relaxation times has been looked at.
Publication Name: Canadian Journal of Chemistry
Subject: Chemistry
ISSN: 0008-4042
Year: 1998
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