Subject europium

By means of a stopped-flow technique, Carlyle and Espenson ° ° have subjected the reaction between europium(II) and iron(III) to a detailed examination. In perchloric acid solution two processes are discerned, viz. 

Iieser et al. [628] studied the application of neutron activation analysis to the determination of trace elements in seawater. The rare earths included in this study were cerium and europium. The element concerned were adsorbed onto charcoal. Between 75% and 100% of the elements were adsorbed onto the charcoal which was then subjected to analysis by neutron activation analysis. Cerium (300 p,g/l) and europium (0.00082 pg/1) were found in North Sea water by this method. 

This volume provides the first unified treatment of the coordination die-mistry and spectral diaracteristics of europium and its complexes. The subject has been reviewed balancing the experimental facts with the theory as far as possible. 

Acid soluble rare earth salt solution after the removal of cerium may be subjected to ion exchange, fractional crystalhzation or solvent extraction processes to separate individual rare earths. Europium is obtained commercially from rare earths mixture by the McCoy process. Solution containing Eu3+ is treated with Zn in the presence of barium and sulfate ions. The triva-lent europium is reduced to divalent state whereby it coprecipitates as europium sulfate, EuS04 with isomorphous barium sulfate, BaS04. Mixed europium(ll) barium sulfate is treated with nitric acid or hydrogen peroxide to oxidize Eu(ll) to Eu(lll) salt which is soluble. This separates Eu3+ from barium. The process is repeated several times to concentrate and upgrade europium content to about 50% of the total rare earth oxides in the mixture. Treatment with concentrated hydrochloric acid precipitates europium(ll) chloride dihydrate, EuCb 2H2O with a yield over 99%. 

One group was used for spin-on deposition of europium-containing sol prepared from aqueous-alcoholic solution of Ti(OC2Hs)4 precursor and europium nitrate [5]. Then the sample was subjected to heat treatment at 200°C for 30 min... 

For the second group of samples the photoresist was removed (Fig. le) and the samples were anodized in the electrolyte of orthophosphoric acid (Fig. 1 f). Then europium was introduced in the pores of the anodic alumina by immersion of specimen in alcoholic solution of europium nitrate [6]. The specimens were immersed for 2 days and, after removal, subjected to heat treatment within the temperature range of200-500 °C for 30 min (Fig. Ig). 

Europium and PAA luminescences from the second group of specimens, subjected to sequential anodizing in two electrolytes (Fig. Ig) were excited efficiently with 337 nm light (Fig. 3). The PL spectrum measured from the area of aluminium films anodized initially in oxalic acid electrolyte into open windows (Fig. ld,e) reveals mainly strong blue luminescence band of PAA (Fig. 3a). Significantly, red emission from this area of the sample is not observed. At the same time, the PL spectrum measured from the area of... 

The products of the asymmetric alkylation have been used as key building blocks in syntheses of morphanes, phyllanthocin, and periplanone B natural products. In the case of the synthesis of the morphane skeleton, a phenolic nucleophile was reacted with cyclohexenyl methyl carbonate and the resulting ether was subjected to a europium-induced Claisen rearrangement followed by an intramolecular aldehyde-ene reaction to generate the key tricyclic intermediate. Scheme 27 [56]. 

The first test of the theory was made to the solution spectra of Hoogschagen and Gorter (1948) for Nd 4f and Er 4f . This involved summing over the quantum numbers n and ji, since the sublevel structure becomes blurred to at least some degree when the lanthanides are in solution. A remarkably good fit could be made to the experimental data with just three parameters, corresponding to t = 2, 4 and 6 (Judd 1962). The field soon developed a life of its own and is the subject of the review by Carnall (1979) in the third volume of this Handbook. Axe (1963) examined the fluorescence bands Dq F4 and Di - F3, F4 in europium ethylsulphate and showed that the theory works equally well for the individual transitions of the type Two other bands, Do-> Fi and Di - F2, were... 

Closely related to the heavy fermions and spin fluctuators are the valence fluctuation/intermediate valence materials. The origin of this phenomenon starts with cerium and its a 7 transformation (see sections 3.3.4 and 3.7.2). Today it involves many cerium materials and also compounds of samarium, europium, thulium and ytterbium. Because of the breadth of the subject matter and space limitations in this chapter we refer the reader to the following reviews Jayaraman (1979), Lawrence et d. (1981), de Chatel (1982), Coqblin (1982), Nowik (1983), Brandt and Moshchalkov (1984), Varma (1985) and Stassis (1986). 

The only data that have been provided on Gd levels in plasma and urine of healthy subjects were those of Allain et al. [16] reporting normal concentrations of the element in these biological fluids to be <0.3 p.g/liter. Data on the tissue distribution of Gd are scarce. As for some other medium lanthanides, i.e., the subgroup of lanthanides that comprises the elements from europium (Eu) to holmium (Ho), the element is supposed to be equally deposited in the liver and the skeleton [2]. Administration of Gd-DOTA and Gd-DTPA contrast agents in rats resulted in a 0. l-1.0% retention in liver and spleen [17]. 

Meggers 1942) and that of element 61 is obtained by interpolation consequently, these are subject to some doubt. The ground states given for neodymium (Schuurmans 1946), samarium, europium and gadolinium are those spectroscopically determined (Meggers 1942) for the neutral atoms and should be considered as well established. 

R.G. Barnes, NMR, EPR and Mossbauer effect metals, alloys and compounds 387 P. Wachter, Europium chalcogenides EuO, EuS, EuSe and EuTe 507 A. Jayaraman, Valence changes in compouruls 575 Subject index 613... 

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