scholarly journals Spectral Characterization and Excited-State Interactions Between Rare Earth Ions Doped in Borosilicate and Sol-Gel Glasses: Energy Transfer Up-Conversion in the Pr-Sm System

1996 ◽  
Vol 455 ◽  
Author(s):  
Z. Assefa ◽  
R. G. Haire ◽  
N. A. Stump
Keyword(s):  
Energy Transfer ◽  
Excited State ◽  
High Temperature ◽  
Electric Dipole ◽  
Sol Gel ◽  
Local Symmetry ◽  
Rare Earth Ions ◽  
Photon Absorption ◽  
Gel Glasses ◽  
Glass Matrices

ABSTRACTSpectroscopie properties of selected 4f-elements in a sol-gel and two high temperature silicate based glasses are reported. In particular, the spectral properties of the Eu3+ ion have been used to probe the local coordination environment of the f-elements in these glass matrices. Luminescence studies of the high temperature glasses indicated that the electric dipole allowed f-f transitions dominate the spectra which suggests that the local symmetry around the 4f-ions is low. Temperature-dependent spectroscopie studies of the sol-gel glasses indicated that the f-elements retain a “solution-like” environment prior to thermal processing. After heat treatment, an increase in the emission intensities of the electric-dipole transitions is accompanied by a concomitant decrease in the magnetic-dipole allowed transitions. Moreover, excited state interactions has also been observed in the high temperature glasses that contain certain multiple f-elements. In Pr-Sm systems, exclusive excitation of the Sm3+ ion with a 514 nm argon ion laser line provides a higher-energy emission band (ca. 490 nm) from the Pr3+ ion (3P0 → 3H4) transition. This energy up-conversion is attributed to energy transfer from the 6H13/2 level of the Sm3+ ion to the 3Hg6 state of the Pr3+ ion. Following a second photon absorption, the Pr3+ ion is excited to the emitting 3P0level.

Fundamental Science of f-Elements in Selected Immobilization Glasses: Significance for TRU Disposal Schemes

1997 ◽  
Vol 506 ◽  
Author(s):  
R. G. Haire ◽  
Z. Assefa ◽  
N. Stump
Keyword(s):  
High Temperature ◽  
Materials Science ◽  
Sol Gel ◽  
Oxidation States ◽  
Melting Points ◽  
The Third ◽  
Oxidation Potentials ◽  
The Stability ◽  
Gel Glasses ◽  
Glass Matrices

ABSTRACTWe have investigated certain aspects of the fundamental chemistry and materials science of the 4fand several 5f-elements in three glass matrices. Two of these matrices were high-temperature (850° and 1450°C melting points) silicate-based glasses and the third was a sol-gel glass. Optical spectroscopy was the principal investigating tool. One aspect of the work here was to ascertain the oxidation state exhibited by these elements in the different glasses, as well as the factors that control and/or may alter this state. An important finding was noting a general correlation between the oxidation states obtained in the two high-temperature glasses and those observed in the oxides of these elements. Of the twenty three f-elements considered here, only three exceptions (Ce, Am and Bk) or examples of variable behavior (Pr, Tb, U and Cf) to this correlation were noted. One explanation offered for the exceptions is based on the stability afforded by the oxides' fluorite lattice. The correlation also applied to the sol-gel glasses after they had been heated. Other oxidation states for some elements could be obtained in the sol-gel glasses prepared at 25°C. Presented here is a summary of the oxidation states observed for these elements in three glass matrices and how these states correlate with those observed in the oxides of these elements and with the relative oxidation potentials for the elements.

scholarly journals Fundamental Chemistry and Materials Science of Americium in Selected Immobilization Glasses

1996 ◽  
Vol 465 ◽  
Author(s):  
R. G. Haire ◽  
N. A. Stump
Keyword(s):  
High Temperature ◽  
Oxidation State ◽  
Materials Science ◽  
Sol Gel ◽  
Melting Points ◽  
Pertinent Data ◽  
High Temperature Oxide ◽  
Temperature Oxide ◽  
Gel Glasses ◽  
Glass Matrices

ABSTRACTWe have pursued some of the fundamental chemistry and materials science of americium in three glass matrices, two being high-temperature (850° and 1400°C melting points) silicate-based glasses and the third a sol-gel glass. Optical spectroscopy was the principal investigating tool in the studies. One aspect of this work was to determine the oxidation state exhibited by americium in these matrices, as well as factors that control and/or may alter this state. We have noted a correlation between the oxidation state of the f-elements in the two high-temperature glasses with their high-temperature oxide chemistries. One exception was americium: although americium dioxide is the stable oxide encountered in air, when this dioxide was incorporated into the high-temperature glasses, only trivalent americium was found in the products. When trivalent americium was used to prepare the sol-gel glasses at ambient temperature, and after these products were heated in air to 800°C, again only trivalent americium was observed. Potential explanations for the unexpected behavior of americium is offered in the context of its basic chemistry. Experimental spectra, spectroscopie assignments and other pertinent data obtained in the studies are discussed.

Energy transfer between UO22+ and Eu3+ in sol-gel glasses: a spectroscopic investigation

1996 ◽  
Vol 262 (3-4) ◽  
pp. 315-320 ◽  
Author(s):  
Sheng Dai ◽  
Wu Xu ◽  
D.H. Metcalf ◽  
L.M. Toth
Keyword(s):  
Energy Transfer ◽  
Spectroscopic Investigation ◽  
Sol Gel ◽  
Gel Glasses

Cooperative energy transfer in Yb3+–Tb3+ codoped silica sol-gel glasses

2001 ◽  
Vol 89 (5) ◽  
pp. 2520-2524 ◽  
Author(s):  
I. R. Martı́n ◽  
A. C. Yanes ◽  
J. Méndez-Ramos ◽  
M. E. Torres ◽  
V. D. Rodrı́guez
Keyword(s):  
Energy Transfer ◽  
Sol Gel ◽  
Silica Sol ◽  
Gel Glasses ◽  
Cooperative Energy

Structural and optical characterization of CdSe nanocrystallites/rare earth ions in sol–gel glasses

2007 ◽  
Vol 29 (11) ◽  
pp. 1495-1500 ◽  
Author(s):  
Gijo Jose ◽  
Cyriac Joseph ◽  
M.A. Ittyachen ◽  
N.V. Unnikrishnan
Keyword(s):  
Rare Earth ◽  
Sol Gel ◽  
Optical Characterization ◽  
Rare Earth Ions ◽  
Gel Glasses

Chromophore Dynamics in Sol-Gel Glasses and Xerogel Clad Fiber Optic Sensors

1994 ◽  
Vol 346 ◽  
Author(s):  
Drew L'Esperance ◽  
Clarice A. Browne ◽  
Eric L. Chronister
Keyword(s):  
Energy Transfer ◽  
Fiber Optic ◽  
Rotational Diffusion ◽  
Sol Gel ◽  
Fiber Optic Sensors ◽  
Fiber Optic Sensor ◽  
Time Resolved ◽  
Optic Sensor ◽  
Sensor Device ◽  
Gel Glasses

ABSTRACTTime-resolved depolarization measurements are used to investigate rotational diffusion and optical energy transfer dynamics of chromophores incorporated into silica and aluminosilica solutions, gels, and glasses. The use of an organically doped sol-gel clad waveguide as a novel intrinsic fiber optic sensor device is also demonstrated, and advantages of time-resolved detection of the fiber optic sensor are illustrated.

Local symmetry and Z-scan analysis of ZnSe/Eu3+ doped sol–gel silica hosts

2010 ◽  
Vol 88 (7) ◽  
pp. 493-500 ◽  
Author(s):  
Siby Mathew ◽  
K. V. Arun Kumar ◽  
C. Sudarsanakumar ◽  
V. P.N. Nampoori ◽  
N. V. Unnikrishnan
Keyword(s):  
Rare Earth ◽  
Sol Gel ◽  
Glass Network ◽  
Local Symmetry ◽  
Wide Distribution ◽  
Rare Earth Ions ◽  
Saturable Absorption ◽  
Rare Earth Ion ◽  
Enhanced Absorption ◽  
The Rare Earth

Vibrational state side-band spectral analysis of silica matrices, doped with ZnSe/Eu3+ ions, associated with the excitation transition 7F0→5D2 is used to analyze the local asymmetry of the rare earth ions in the glass host. The large inhomogeneous linewidth for the ZnSe co-doped samples indicates the wide distribution of the Eu3+ ions in the matrix and is related to the flexibility of the local glass network. The fluorescence spectra reveal that the intensity of the characteristic emission of europium increases considerably in the presence of ZnSe particles. This phenomenon can be explained by the energy transfer resulting from electron–hole recombination in the ZnSe to the rare earth ion. Nonlinear optical absorption of the sample is also investigated at a wavelength of 532 nm, using open aperture Z-scan technique. The sample exhibits reversible saturable absorption (RSA), which is found to depend on excitation fluence. RSA is due to the enhanced absorption resulting from the electron dynamics in nano-crystallites.

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