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Pursuit of the Ultimate Regression Model for Samarium(III), Europium(III), and LiCl Using Laser-Induced Fluorescence, Design of Experiments, and a Genetic Algorithm for Feature Selection
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Europium doping of cadmium selenide (CdSe) quantum dots via rapid microwave synthesis for optoelectronic applications
UV-Vis spectroscopy and PL data show that structural incorporation of Eu 3+ has an effect on the optical properties of CdSe QDs via energy transfer from host to dopant. This allows for QDs with tunable optical properties via numerous pathways.
Europium-151 and iron-57 nuclear resonant vibrational spectroscopy of naturally abundant KEu( iii )Fe( ii )(CN) 6 and Eu( iii )Fe( iii )(CN) 6 complexes
We have performed and analyzed the first combined 151 Eu and 57 Fe nuclear resonant vibrational spectroscopy (NRVS) for naturally abundant KEu( iii )[Fe( ii )(CN) 6 ] or Eu( iii )[Fe( iii )(CN) 6 ] complex.
Amplified spontaneous emission from europium-based molecular complexes coupled to photonic crystal cavities
Rare-earth ion-based materials bear many remarkable optical properties that render them highly appealing for lighting and quantum-related applications. However, their small oscillator strength and weak emission often pose limitations. Here, in this work, we synthesize and couple Eu(III)-based molecular complexes to nanobeam photonic crystals supporting air modes. A reasonable spatial overlap between the molecular complexes and cavity modes leads to an average spontaneous emission coupling efficiency of 0.19. Our pump power-dependent photoluminescence measurements evidence amplified spontaneous emission from the molecular complexes with an amplification threshold as low as 4.4 W/cm 2 , likely benefiting from the efficient coupling. These findings suggest that integrating rare-earth ion-based molecular complexes with photonic structures could be a viable approach for regulating their emission characteristics for particular applications.
Europium c -axis ferromagnetism in Eu ( Co 1 - x Ni x ) 2 - y As 2 : A single-crystal neutron diffraction study
Here we report neutron diffraction results for the body-centered-tetragonal series Eu(Co 1-x Ni x ) 2-y As 2 , x=0.10, 0.20, 0.42, and 0.82, y≤0.10, that detail changes to the magnetic ordering with nominal hole doping. We report the antiferromagnetic (AFM) propagation vectors, magnetic transition temperatures, and the ordered magnetic moments. We find a nonmonotonic change of the AFM propagation vector with x, with a minimum occurring at the tetragonal to collapsed-tetragonal phase crossover. For x=0.10 and 0.82 we find c-axis helix ordering of the Eu magnetic moments (spins) similar to x=0 and 1, with the spins oriented within the ab-plane. For x=0.20 and 0.42 we find higher-temperature c-axis ferromagnetic (FM) order and lower-temperature c-axis cone order. Using the extinction conditions for the space group, we discovered that the Eu spins are ordered in the higher-temperature c-axis FM phase for intermediate values of x, contrary to a previous report suggesting only Co/Ni spin ordering. Although we cannot directly confirm that the Co/Ni spins are also ordered, we suggest that c-axis itinerant-FM ordering of the Co/Ni spins could provide a molecular field that drives FM ordering of the Eu spins, which in turn provides the anisotropy for the lower-temperature c-axis cone order.
Crystal Growth and Characterization of Europium-Doped Rubidium Calcium Bromide Scintillators
National security strategies like gamma spectroscopy and high-energy X-ray radiography are limited, in part, by the scintillator used, prompting research into novel materials with improved properties. In this paper, Eu 2+ activated rubidium calcium bromide scintillators were grown via the vertical Bridgman method with a range of dopant concentrations. Light yield, energy resolution, and the afterglow of Rb 4 CaBr 6 :Eu and RbCaBr 3 :Eu improved with increasing Eu 2+ concentration, and scintillation decay time increased. The highest light yields of Rb 4 CaBr 6 :Eu and RbCaBr 3 :Eu were 71000 and 45000 ph/MeV, respectively.
Spectral broadening of europium ions in glass
Spectral broadening mechanisms for trivalent Eu ions in glass, considering fluorescence and absorption spectra measurements
On the abundance of Europium
The inclusion of the effects of hyperfine splitting can significantly lower the abundance estimate of Eu from singly ionized lines which lie on the flat portion of the curve of growth. In the 21 cool Ap stars studied by Adelman and the five Am stars studied by Smith, the Eu abundance was reduced by 0.4 dex on the average. In individual cases, the reductions were as great as 0.9 dex. This makes the Eu abundance comparable to that of its neighboring rare earths Sm and Gd in the Ap stars and less than Sm and Gd in the Am stars, but still substantially overabundant with respect to solar values.
EPR measurement of the effect of glass composition on the oxidation states of europium
An investigation was conducted concerning the dependence of the concentration ratio of Eu(2+) to Eu(3+) on composition for silicate liquids whose compositional end members are CaAl2Si2O8 and MgSiO3, MG2SiO4, CaMgSi2O6, CaMgSiO4, CaSiO3, or Ca2SiO4. The liquids were quenched to produce glasses. An electron paramagnetic resonance spectrometer was used to determine the concentration ratios of Eu(2+) to Eu(3+) in the glasses.
Measurement of the effects of temperature and partial pressure of oxygen on the oxidation states of europium in silicate glasses
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The oxidation state of europium as an indicator of oxygen fugacity
Empirical oxygen barometers based on Eu(2+)/Eu(3+) ratios in plagioclase feldspar and magmatic liquid were developed using Philpott's (1970) approach and the experimental data of Drake (1972). Oxygen fugacities calculated on the basis of Eu(2+)/Eu(3+) ratios for terrestrial basalts cluster tightly around 10 to the negative seventh power. Oxygen fugacities for Apollo 11 and 12 lunar ferrobasalts cluster tightly around 10 to the negative 12.7 power. Calculated oxygen fugacities for achondritic meteorites are lower than for lunar samples by several orders of magnitude.
Europium mass balance in polymict samples and implications for plutonic rocks of the lunar crust
The mean concentrations of Sm and Eu in the lunar surface crust were analyzed by correlating the Sm concentration and the Sm/Eu ratio with Th concentration obtained from published data on a large number of polymict samples from various locations in the lunar highlands, and using the value of 0.91 microg/g for the mean Th concentration of the highlands surface crust obtained by the orbiting gamma-ray experiments. The mean concentration of Sm in the lunar surface crust was found to be between 2 and 3 microg/g, and that of Eu between 0.7 and 1.2 microg/g. The results indicate that there is no significant enrichment or depletion of Eu, compared to Sm, relative to chondritic abundances; i.e., there is no significant 'Eu anomaly' in average upper crust, contrary to predictions by some earlier investigators.
Europium anomalies in mare basalts as a consequence of mafic cumulate fractionation from an initial lunar magma
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Optical fiber spectroscopy: A study of the luminescent properties of the europium ion for thermal sensors
Recently, there has been interest in developing a distributed temperature sensor integrated into an optical fiber. Such a system would allow embedding of the optical fiber within or on a structural material to provide for continuous monitoring of the material's temperature. Work has already begun on the development of a temperature sensor using the temperature dependent emission spectra from the lanthanide rare earths doped into crystalline hosts. The lifetime, the linewidth and the integrated intensity of this emission are each sensitive to changes in the temperature and can provide a basis for thermometry. One concept for incorporating this phenomena into an optical fiber based sensor involves bonding the optically active material to the cladding of an optical fiber and allowing the luminescent light to couple into the the fiber by the evanescent wave. Experimental work developing this concept has already been reported. Measurements of the linewidth of Eu3+:Y2O3, diffused into a fiber, made by Albin clearly show a strong and regular dependence on temperature over the range of 300 to 1000 K. We report here on a study of the temperature dependence of the lineshape of the emission at 611 nm using the data in references. We focus attention on understanding the general behavior of the Eu3+:Y2O3 system. Building upon understanding of this system we will be able to establish the physical criterial for a good optical fiber based temperature sensor and then to examine available data on other lanthanide rare earths and transition metal ions to determine the best luminescent system for temperature sensing in an optical fiber.
Oxygen Fugacity of the Martian Mantle from Pigeonite/Melt Partitioning of Samarium, Europium and Gadolinium
This study is part of an ongoing effort to calibrate the pyroxene/melt REE oxybarometer for conditions relevant to the martian meteorites. These efforts have been motivated by reports of redox variations among the shergottites . We have conducted experiments on martian composition pigeonite/melt rare earth element partitioning as a function of fO2.
Oxygen Fugacity of the Martian Mantle from Pigeonite/Melt Partitioning of Samarium, Europium and Gadolinium
This study is part of an ongoing effort to calibrate the pyroxene/melt Eu oxybarometer for conditions relevant to the martian meteorites. There is fairly good agreement between a determinations using equilibria between Fe-Ti oxides and the estimates from Eu anomalies in shergottite augites in tenns of which meteorites are more or less oxidized. The Eu calibration was for angrite composition pyroxenes which are rather extreme. However, application of a calibration for martian composition augites 113 does not significantly reduce the discrepancy between the two methods. One possible reason for this discrepancy is that augites are non-liquidus. The use of pigeonite rather than augite as the oxy-barometer phase is considered. We have conducted experiments on martian composition pigeonite/melt REE partitioning as a function of fO2.