Spectroscopic Studies of Chemical Reactions and Dynamics in Sol-Gel Matrices

1994 ◽  
Vol 346 ◽  
Author(s):  
F. Akbarian ◽  
B. Dunnt ◽  
P.D. Fuquat ◽  
J. Mckiernan ◽  
E. Simoni ◽  
...  
Keyword(s):  
Chemical Reactions ◽  
Optical Materials ◽  
Copper Phthalocyanine ◽  
Sol Gel ◽  
Spectroscopic Studies ◽  
Pump Probe ◽  
Silica Monoliths ◽  
Sol Gel Process ◽  
Different Types ◽  
Gel Glasses

ABSTRACTThe synthesis of sol-gel glasses containing organic and organometallic molecular dopants has been well established as an approach for creating new optical materials. Some of these properties are dependent upon chemical reactions which occur in porous xerogel matrices during the sol-gel process or when encapsulated molecules are exposed to other molecules in solution. In this paper, the study of two different types of chemical reactions in the pores of xerogel matrices is reported. In one case copper phthalocyanine is used to characterize dimerization within the pores. The results show that dimer formation is most likely to occur towards the end of the drying stage as the dye concentration in the pores increases from solvent evaporation. A second example involves the use of a pump-probe technique to determine the rate of proton recombination inside the pores of silica monoliths. The behavior of sols and gels is similar to aqueous solution while recombination of protons in the xerogel seems to be affected by the walls of the pores.

The use of multinuclear solid state NMR for the characterization of siloxane-oxide hybrid nanocomposites

2004 ◽  
Vol 847 ◽  
Author(s):  
Christel Gervais ◽  
Beatriz Julián ◽  
Eloisa Cordoncillo ◽  
Purificación Escribano ◽  
Mark E. Smith ◽  
...  
Keyword(s):  
Solid State ◽  
Solid State Nmr ◽  
Sol Gel ◽  
Hybrid Nanocomposites ◽  
Sol Gel Process ◽  
Hydrolysis And Condensation ◽  
Silicon Alkoxides ◽  
Different Types ◽  
Nmr Techniques

ABSTRACTThe objective of this paper is to review various solid state NMR techniques that have been, or can be used for the structural characterization of siloxane—oxide hybrid systems prepared by sol-gel process, and to discuss the type of information they provide, as well as their limitations. More precisely, this paper focuses on NMR techniques to probe and quantify the different types of oxo-bridges (M–O–M of oxide network, Si–O–Si of siloxane chains and Si–O–M siloxane–MxOy interface) in siloxane-oxide nanocomposites prepared through hydrolysis and condensation of organosilanes and M(OR)n alkoxides. In addition the influence of the functionality of the silicon alkoxides and the nature of the MxOy oxides on the extent of the Si-O-M interface will be examined.

Photoinduced Birefringence in Nanostructured SiO2:DR1 Sol–Gel Films

2008 ◽  
Vol 8 (12) ◽  
pp. 6576-6583
Author(s):  
Alfredo Franco ◽  
Jorge A. García-Macedo ◽  
I. G. Marino ◽  
P. P. Lottici
Keyword(s):  
Cetyltrimethylammonium Bromide ◽  
Sol Gel ◽  
Sodium Dodecyl ◽  
X Ray Diffraction ◽  
Pump Probe ◽  
Heat Treated ◽  
Sol Gel Process ◽  
Photoinduced Birefringence ◽  
Xrd Patterns ◽  
Sol Gel Films

Pump-probe photoinduced birefringence measurements were carried out in amorphous and in nanostructured sol–gel films with Disperse Red 1 (DR1) azochromophores embedded in a SiO2 matrix. X-ray diffraction (XRD) patterns determine the long-range nanostructure order of the films, exhibiting a lamellar nanostructure, with two different d-spacings, due to the presence during the sol–gel process of the Sodium Dodecyl Sulfate (SDS) or of the Cetyltrimethylammonium Bromide (CTAB) ionic surfactants. The photoinduced birefringence measurements were performed on fresh and on heat treated films as a function of the pumping time. The measurements give us information about the effect of the nanostructures on the azochromophores orientation dynamics. As a result, for the same azochromophores concentration, annealed nanostructured films exhibited the largest azochromophore mobilities but by the other side, amorphous films had the largest signal intensities. Besides, we established a phenomenological model for the analysis of the azochromophores orientation in the films as a function of the pumping time.

LIMITING DYNAMICS OF C60 IN SOLID MATRICES

2000 ◽  
Vol 09 (03) ◽  
pp. 315-342 ◽  
Author(s):  
J. SCHELL ◽  
R. LÉVY ◽  
B. HÖNERLAGE
Keyword(s):  
Singlet State ◽  
Sol Gel ◽  
Saturable Absorption ◽  
Reverse Saturable Absorption ◽  
Solid Samples ◽  
Pump Probe ◽  
Crystalline Films ◽  
Level Model ◽  
Gel Glasses ◽  
Pulse Pump

We study the limiting dynamics of C 60-doped porous sol-gel glasses by single- and double-pulse pump-probe experiments. We find that, contrary to crystalline films of C60, reverse saturable absorption (RSA) of these solid samples can be described by a 5-level model developed for C 60-solutions. We observe an ultrafast rise time, a large transmission-decrease at high fluence, a shortened singlet-state lifetime as compared to solutions, but nevertheless an important triplet yield. We explain differences with respect to solutions by the absence of stabilizing aromatic solvents and by the interaction of the amorphous environment with the molecules, broadening considerably the spectral features of RSA.

On-Line Spectroscopic Studies of Group iv Alkoxides and their Interactions with Polymerizable Organic Additives During the Sol-Gel Process

1998 ◽  
Vol 519 ◽  
Author(s):  
R. Cinier ◽  
J. Guilment ◽  
O. Poncelet ◽  
S. Truchet ◽  
D. Wettling
Keyword(s):  
Sol Gel ◽  
Nir Spectroscopy ◽  
Relevant Information ◽  
Spectroscopic Studies ◽  
Organic Additives ◽  
Hydrolysis Process ◽  
Sol Gel Process ◽  
On Line ◽  
Versatile Technique ◽  
Ir And Raman

AbstractThe monitoring of different reactions such as the stabilization of the alkoxides with polymerizable organic additives, the building of the inorganic network during the hydrolysis process, and in a same manner, the polymerization of the organic additives, can be of great importance for the development of hybrid materials with improved processability.NIR spectroscopy is a very versatile technique but lacks of specificity. IR and Raman give more interpretative results but are not always easy to run on a process. We used both techniques along with chemometric tools to extract relevant information from our processes. Then 2D correlation allowed to benefit from the specificity of IR and Raman to develop robust NIR methods able to be used on line to control the different steps of the sol-gel process.The hydrolysis of mixed species of titanium containing chloro, isopropoxo and methacrylato ligands will be discussed in terms of mechanism occuring during the sol-gel process.

Hybrid Nonlinear Optical Materials Containing Imidazole Chromophore through the Sol-Gel Process

2007 ◽  
Vol 28 (20) ◽  
pp. 2019-2023 ◽  
Author(s):  
Yuanjing Cui ◽  
Guodong Qian ◽  
Lujian Chen ◽  
Zhiyu Wang ◽  
Minquan Wang
Keyword(s):  
Optical Materials ◽  
Nonlinear Optical ◽  
Sol Gel ◽  
Nonlinear Optical Materials ◽  
Sol Gel Process

Comparisons and analyses on heterostructures consisting of ZnO and different ferroelectric films

2011 ◽  
Vol 1368 ◽  
Author(s):  
Nai-wen ZHANG ◽  
Ze JIA ◽  
Ming-ming ZHANG ◽  
Tian-ling REN
Keyword(s):  
Remnant Polarization ◽  
Sol Gel ◽  
Semiconductor Heterostructures ◽  
Ferroelectric Films ◽  
Channel Resistance ◽  
Current Voltage ◽  
Sol Gel Process ◽  
Different Types ◽  
Current Voltage Characteristics

ABSTRACTTwo different types of ferroelectric/semiconductor heterostructures, made up of Pb(Zr,Ti)O3/ZnO and BiFeO3/ZnO respectively, were fabricated on Pt(111)/Ti/SiO2/Si(100) by sol-gel process. Obvious diodelike behavior were observed in BiFeO3/ZnO heterostructures when current-voltage characteristics were measured, while Pb(Zr,Ti)O3/ZnO heterostructures exhibited a symmetrical behavior. It is found that Pb(Zr,Ti)O3/ZnO heterostructures showed a large polarization and the remnant polarization was approximately 15μC/cm2. The remnant polarization performed a modulation on the channel resistance. The different properties of two heterostructures might lead to different applications.

Self-encapsulation of a drug-containing ionic liquid into mesoporous silica monoliths or nanoparticles by a sol–gel process

RSC Advances ◽  
2016 ◽  
Vol 6 (86) ◽  
pp. 82916-82923 ◽  
Author(s):  
David Brevet ◽  
Claire Jouannin ◽  
Corine Tourné-Péteilh ◽  
Jean-Marie Devoisselle ◽  
André Vioux ◽  
...  
Keyword(s):  
Ionic Liquid ◽  
Mesoporous Silica ◽  
Sol Gel ◽  
Silica Monoliths ◽  
Templating Agent ◽  
Sol Gel Process

Mesoporous silica monoliths and nanospheres were obtained using the same ionic liquid acting as a templating agent and catalyst.

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