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51.
Victor L. Cherginets T.P. Rebrova A.L. Rebrov O.I. Yurchenko 《Physics and Chemistry of Liquids》2017,55(2):248-253
The interaction of Eu2O3 with molten NaBr–NaI (0.77:0.23) mixture at 973 K was studied by sequential addition method with the use of YSZ membrane oxygen electrode for controlling of course of the process. The Red-Ox process is accompanied with formation of EuO in the melt. The total solubility of EuO (sum of concentration of Eu2+, O2–, non-dissociated EuO) in the molten NaBr–NaI at 973 K (mole fraction 2.7 × 10–4) is considerably lower than in pure NaI melt (4.2 × 10–4), which can be explained using the ‘hole’ model by reduction of a number of holes of comparable with EuO particle size because of addition of smaller bromide ion to the iodide melt.The solubility of EuO is appreciably affected by its dispersity and the value of surface energy causing these solubility changes is estimated as 37 J m–2. 相似文献
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54.
吡啶—2,6—二羧酸体系导数荧光法同时测定铀,钐,铕,铽,镝 总被引:4,自引:0,他引:4
本研究了吡啶-2,6-二羧酸(DPA)体系导数荧光法同时测定铀,钐,铕,铽,镝的最佳条件。在pH5.5,4.8×10^-^5mol/LDPA,激发波长272nm的条件下,可分别在518,639,621,539和66nm处测定铀,钐,铕,铽和镝,检测限分别达到7,0.4,0.004,0.026和0.25ng/mL。应用本法测定了混合成试液中上术五种离子含量,回收率为92.3-108.1%。 相似文献
55.
Isolated-core-excitation (ICE) scheme and autoionization detection
are employed to study the bound Rydberg states of europium atom. The
high-lying states with odd parity have been measured using the
autoionization detection method with three different excitation
paths via 4f76s6p[ 8P5/2], 4f76s6p[ 8P7/2]
and 4f76s6p[ 8P9/2] intermediate states, respectively. In
this paper the spectra of bound Rydberg states of Eu atom are
reported, which cover the energy regions from 36000~cm-1 to
38250~cm-1 and from 38900~cm-1 to 39500 cm-1.
The study provides the information about level energy, the possible
J values and relative line intensity as well as the effective
principal quantum number n^* for these states. This work not only
confirms the previous results of many states, but also discovers 11
new Rydberg states of Eu atom. 相似文献
56.
Dr. Csongor Szíjjártó Elias Pershagen Nadia O. Ilchenko Dr. K. Eszter Borbas 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(9):3099-3109
Coumarin‐sensitized, long‐wavelength‐absorbing luminescent EuIII‐complexes have been synthesized and characterized. The lanthanide binding site consists of a cyclen‐based chelating framework that is attached through a short linker to a 7‐hydroxycoumarin, a 7‐B(OH)2‐coumarin, a 7‐O‐(4‐pinacolatoboronbenzyl)‐coumarin or a 7‐O‐(4‐methoxybenzyl)‐coumarin. The syntheses are straightforward, use readily available building blocks, and proceed through a small number of high‐yielding steps. The sensitivity of coumarin photophysics to the 7‐substituent enables modulation of the antenna‐absorption properties, and thus the lanthanide excitation spectrum. Reactions of the boronate‐based functionalities (cages) with H2O2 yielded the corresponding 7‐hydroxycoumarin species. The same species was produced with peroxynitrite in a ×106–107‐fold faster reaction. Both reactions resulted in the emergence of a strong ≈407 nm excitation band, with concomitant decrease of the 366 nm band of the caged probe. In aqueous solution the methoxybenzyl caged Eu‐complex was quenched by ONOO?. We have shown that preliminary screening of simple coumarin‐based antennae through UV/Vis absorption spectroscopy is possible as the changes in absorption profile translate with good fidelity to changes in EuIII‐excitation profile in the fully elaborated complex. Taken together, our results show that the 7‐hydroxycoumarin antenna is a viable scaffold for the construction of turn‐on and ratiometric luminescent probes. 相似文献
57.
IntroductionLanthanidecomplexeshaveattractedmuchattentionbecauseoftheirimportantapplications .1InparticularEu(III)andTb(III)canbecharacterizedbylong lived(mstimescale)andstrongluminescentelectronicallyex citedstates ,whichmakesthemimportantinanalyticalchem… 相似文献
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59.
Christian Merten Honggang Li Xuefang Lu Andreas Hartwig Laurence A. Nafie 《Journal of Raman spectroscopy : JRS》2010,41(12):1563-1565
Natural resonance electronic Raman optical activity (ROA) is observed for the first time. Coincidently, the first example of vibrational ROA enhanced by low‐lying electronic transition is reported. These new phenomena were measured using the rare‐earth complex Eu(tfc)3 (+)‐tris[3‐trifluoroacetyl‐D ‐camphorato]europium(III), where electronic resonance occurs between the 532‐nm laser excitation and the 7F1 → 5D1 transition of the Eu3+ metal center. Electronic Raman spectra involve the Raman transitions terminating on the low‐lying electronic states of Eu(tfc)3. The observed vibrational ROA spectra are enhanced relative to typical ROA spectra by the proximity of vibrational states of Eu(tfc)3 to its low‐lying electronic states with significant magnetic‐dipole character, whereas the parent vibrational Raman spectra do not appear to be resonance‐enhanced since the 532‐nm vibrational Raman spectrum has similar relative intensities to the corresponding Raman spectrum measured with 1064‐nm laser excitation. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
60.
Oxidative Conversion of a Europium(II)‐Based T1 Agent into a Europium(III)‐Based paraCEST Agent that can be Detected In Vivo by Magnetic Resonance Imaging 下载免费PDF全文
Dr. Alexander M. Funk Dr. Veronica Clavijo Jordan Prof. A. Dean Sherry Dr. S. James Ratnakar Prof. Zoltan Kovacs 《Angewandte Chemie (International ed. in English)》2016,55(16):5024-5027
The EuII complex of 1,4,7,10‐tetraazacyclododecane‐1,4,7,10‐tetraacetic acid (DOTA) tetra(glycinate) has a higher reduction potential than most EuII chelates reported to date. The reduced EuII form acts as an efficient water proton T1 relaxation reagent, while the EuIII form acts as a water‐based chemical exchange saturation transfer (CEST) agent. The complex has extremely fast water exchange rate. Oxidation to the corresponding EuIII complex yields a well‐defined signal from the paraCEST agent. The time course of oxidation was studied in vitro and in vivo by T1‐weighted and CEST imaging. 相似文献