Absorption terbium

Terbium may be identified by various instrumental techniques including atomic absorption and emission spectrophotometry and neutron activation analysis. 

Oxyhalides. The oxyhalides of yttrium, lanthanum, and gadolinium are good host lattices for activation with other rare-earth ions such as terbium, cerium, and thulium. The use of LaOCl Tb3+ as the green component in projection-television tubes has been discussed [5.419]. LaOBr Tb3+ and LaOBr Tm3+ exhibit high X-ray absorption, and they are used in X-ray intensifying screens [5.420]. 

The Terbium Chloride-Aluminum Chloride Vapor System. I. Absorption and Excitation Spectra, J.A. Caird, W.T. Camall, J.P. Hessler, and C.W. Williams, J. Chem. Phys. 74, 798-804 (1981). 

Another example of a different type of correlation of structural to photophysical properties is shown in a study of a unique terbium compound [63]. This compound will be briefly discussed and is depicted in Figure 7.9 with its nonlinear emission properties with excitation at 800 nm. The photophysical properties are atypical and rather extraordinary due to the unusual molecular structure of the co-crystallization compound (4) of the organic chromophore and the terbium salt This compound shows both multiphoton absorption induced green f-f emission from the terbium ion as well as second-harmonic generation. However, unlike previously... 

Berkelium exhibits both the III and IV oxidation states, as would be expected from the oxidation states displayed by its lanthanide counterpart, terbium. Bk(III) is the most stable oxidation state in noncomplex-ing aqueous solution. Bk(IV) is reasonably stable in solution, undoubtedly because of the stabilizing influence of the half-filled Sf7 electronic configuration. Bk(III) and Bk(IV) exist in aqueous solution as the simple hydrated ions Bk3+(aq) and Bk4+(aq), respectively, unless com-plexed by ligands. Bk(III) is green in most mineral acid solutions. Bk(IV) is yellow in HC1 solution and is orange-yellow in H2S04 solution. A discussion of the absorption spectra of berkelium ions in solution can be found in Section IV,C. 

Four rare-earth elements (yttrium, ytterbium, erbium, and terbium) have been named in honor of this village. A year later, the Swedish chemist Lars Fredrik Nilson (1840-1899), discovered another element in "erbia" and he named it scandium (Sc) in honor of Scandinavia. At the same time, Nilson s compatriot, the geologist and chemist Per Theodor Cleve (1840-1905) succeeded in resolving the "erbia" earths yet another step further, when he separated it into three components erbium, "holmium" (Flo) and thulium (Tm). The name "holmium" refers to Stockholm (Qeve s native city) and had been independently discovered by the Swiss chemists Marc Dela-fontame (1838-1911) and Jacques-Louis Soret (1827-1890), who had coined the metal element X on the basis of its absorption spectrum. 

In absorption spectra, the probability of a transition is expressed by its oscillator strength, /. While / is close to unity for allowed transitions, it is of the order of 10 -10 and 10 -10 respectively for spin-allowed transitions within the 3d and 4f configurations. Efficient conversion of a UV radiation to light (as needed in fluorescent lamps) requires strong absorption properties at the wavelength of incident photons. Figure 1 shows a comparison of the luminescence intensity for 4f- 5d (A/ = 1) and 4f- 4f (A/ = 0) excitations in the case of a terbium compound. 

Contrary to the previous case, parvalbumin binds only two Ca ions. Compared to the technical difficulties encountered at the K-absorption edge of calcium due to increased absorption of 3 A wavelengths, the quantitative replacement of Ca by terbium ions (Lj-edge at 1.648 A) offers an ideal way to obtain structural information about the ion binding sites of parvalbumin by resonance scattering experiments. In fact, Miake-Lye, Doniach and Hodgson were able to determine for the first time the distance between the center of mass of the parvalbumin and its two terbium ion binding sites in solution. 

Fig. I3.X -ray absorption spectra (in arbotrary units) in a region including the terbium L3 edge. The spectra were taken at SSRL beam line 1-5 using a standard transmission EXAFS set up and Si 220 monochromator crystals.

Low-temperature studies of solid tris-bipyridine europium, terbium, lanthanum(III), and sodium clathrochelates were performed on UV excitation [390]. The lanthanum (III) and sodium clathrochelates were examined to get more information on the luminescent properties of the ligand. These clathrochelates showed luminescence at temperatures below 100 K upon longwave UV excitation corresponding to ligand-centred absorption. The quantum yield of the ligand phosphorescence is co 0.02. An increase of temperature results in a drastic decrease in the luminescence intensity, and at 100 K it becomes equal to zero (Fig. 69). 

Absorption and emission of europium (I) and terbium(III) aqua ions and clathrochelates in aqueous solution and in the sohd state [380, 390, 391, 393]. 

The powder contains 0.5 and 0.3 water molecule per europium(III) clathrochelate molecule at 300 K and 4.2 K, respectively, and the quantum yields were calculated to be 0.56 and 0.65, respectively. These values practically coincide with the experimental data. The observed deviation of the quantum yield from 100% for this solid sample is caused by the presence of solvate water molecules [391], The decrease in the luminescence quantum yield in aqueous solutions is also largely caused by an increase in the number of water molecules around the clathrochelate complex. Close to unity luminescence yield for terbium(III) clathrochelate powder may be attributed to the absence of water in this sample. The scheme of the light conversion process absorption - energy transfer emission (A-ET-E) is shown in Fig. 71. 

This is due to the fact that the emission of the tantalate group in YTa04 is at such hi energies (viz. 30000 cm" )> the spectral overlap is no longer with the forbidden narrow absorption lines of the rare earth ions, but with allowed, broad bands. The critical interaction distance, Rq, has been estimated to be 10 A in the case of tantalate to terbium transfer. 

The monochromator is a Ge(220) channel cut. A focussing double crystal monochromator is under development (Goulon and Lemonnier, unpublished work, see section 5.2.4.2). Multiple wavelength data have been collected on terbium parvalbumin at the Lm absorption edge of terbium (Kahn et al 1985) and the structure solved (see 9.7.4). 

The lutetium hahdes (except the fluoride), together with the nitrates, perchlorates, and acetates, are soluble in water. The hydroxide oxide, carbonate, oxalate, and phosphate compotmds are insoluble. Lutetium compounds are all colorless in the solid state and in solution. Due to its closed electronic configuration (4f " ), lutetium has no absorption bands and does not emit radiation. For these reasons it does not have any magnetic or optical importance, see also Cerium Dysprosium Erbium Europium Gadolinium Holmium Lanthanum Neodymium Praseodymium Promethium Samarium Terbium Ytterbium. 

Am. Oiem. Soc- 36, 2060 (1914) by ion exchange Speddtng et al, ibid. 76, 2557 (1954). Prepn of metal by electrodeposition eidem, J. Electrochem. Soc. 100,442 (1953). Absorption spectrum Urbain, foe, cit. Reviews of prepn, proparties and compds of terbium and other lanthanides The Rare... 

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