Europium luminescence spectra

Traditionally, lanthanide-based assays have used ions which emit light in the visible region of the spectrum. Europium has been favored over other alternatives since it has a long luminescence... 

Study of these and other transitions can thus yield valuable information. Crystals of the nine-coordinate complex [Eu(tmhd)3(terpy)] contain two slightly different molecules present in the crystal, its luminescence spectrum showing a broad but imresolved Do Fo transition. In solid [Eu(tmhd)3(Me2phen)] (Ln = La, Eu, Tb, Ho), there are two different square-antiprismatic isomers in the unit cell, and in this case emissions from both isomers can be distinguished in the fluorescence spectrum of the europium complex, which shows an unusually high splitting of the Dq Fq transition. ... 

Fig. 4. The excitation and the luminescence spectrum of the uranyl ion in phosphate glass compared with positions of J-levels in trivalent europium and samarium (taken from Fig. 3)...

Until very recently, studies of the use of luminescent lanthanide complexes as biological probes concentrated on the use of terbium and europium complexes. These have emission lines in the visible region of the spectrum, and have long-lived (millisecond timescale) metal-centered emission. The first examples to be studied in detail were complexes of the Lehn cryptand (complexes (20) and (26) in Figure 7),48,50,88 whose luminescence properties have also been applied to bioassay (vide infra). In this case, the europium and terbium ions both have two water molecules... 

Different lanthanide metals also produce different emission spectrums and different intensities of luminescence at their emission maximums. Therefore, the relative sensitivity of time-resolved fluorescence also is dependent on the particular lanthanide element complexed in the chelate. The most popular metals along with the order of brightness for lanthanide chelate fluorescence are europium(III) > terbium(III) > samarium(III) > dysprosium(III). For instance, Huhtinen et al. (2005) found that lanthanide chelate nanoparticles used in the detection of human prostate antigen produced relative signals for detection using europium, terbium, samarium, and dysprosium of approximately 1.0 0.67 0.16 0.01, respectively. The emission... 

The luminescence center of divalent europium in fluorite is well known (Haber-land et al. 1934 Tarashchan 1978 Krasilschikova et al. 1986 Barbin et al. 1996). It is clearly seen in laser-induced time-resolved luminescence spectra with a decay time of 600-800 ns (Fig. 4.10a). In several samples the band with a spectrum similar to those of Eu + has a very long decay time and remains even after a delay of several ms. Principally it may be connected with energy migration from a UV emitting center with a long decay time, for example, Gd ". ... 

Due to the modifications of the electronic cloud induced by complexation, the quantum yield and the excitation spectrum are also modified. As the direct determination of the absolute quantum yield is very difficult to achieve, one usually finds in the literature quantum yield values determined by comparison to well-known standards, such as quinine sulfate. For example, some values can be found in Georges (1993) or in Klink et al. (2000) for some europium complexes but may be found also in many other papers on lanthanide luminescence. Studies on the correlations between the photophysical properties of a given type of europium complexes and the energy levels can be found in Latva et al. (1997), Klink et al. (2000). A correlation has been found between the excitation properties and the stoichiometry of various Eu(III) complexes (Choppin and Wang, 1997). Note that the changes in the excitation maximum induced by complexation usually amount to a few tenths of nanometers, which requires high resolution for detection. In the case of Eu(III), a correlation has been found between the frequency... 

B. The effect of adding different metals ions on the emission was investigated at pH 7.4. Groups I and II ions, as well as Zn +, had no effect. Addition of Cu + ions shifted the absorption spectrum of the phenanthroline ligand slightly from 255 to 280 nm and caused a substantial quenching of the europium luminescence. This was reversed, with recovery of the europium emission, on adding EDTA solution. Comment on this. 

The excitation spectra of europium and terbium (III) clathrochelates contain a strong dominant band at 27 000 cm-h The CTB at 23 809 cm-i (4.2 K) is mirror-symmetric to the luminescence band. The red emission is detected for the exited europium(III) clathrochelate. The emission spectrum of this complex (Fig. 70) also contains a set of lines corresponding to the °Do —> transitions,... 

Terbium clathrochelate showed green emission of very high intensity. The emission spectrum contains the D4 —> Fj transition bands of the encapsulated terbium ion. The same but less intense emission spectrum was observed at higher temperatures. The luminescence quantum yield is close to 1 at 4.4 K and is approximately 0.05 at room temperature [390]. The decrease in intensity of the terbium(III) ion luminescence starts at 100 K (higher than that of free macrobicyclic tris-bipyridine ligand and lower than that of the corresponding europium(III) compound, Fig. 69). It may be... 

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 trivalent lanthanide (Ln) ions have been known for their unique optical properties such as line-like emission spectra and high-luminescence quantum efficiency (see Luminescence) Historically, detailed research has been almost exclusively devoted to visible-luminescent lanthanide ions, particularly europium and terbium. In the last decade, much effort has focused on the sensitization of NIR-luminescent lanthanides (with Ln = Nd, Er, Yb, Ho, Tm, Dy, Sm, and Pr), which are emissive in the NIR region of the spectrum (750-2500 nm). - ... 

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