L emission spectrum

Figure 8.29 X-ray fluorescence transitions forming (a) a K emission spectrum and (b) an L emission spectrum. The energy levels are not drawn to scale...

Figure 8.31 L emission spectrum of gold. The ] and Yj lines are at 1.277 A and 0.927 A, respectively. (Reproduced, with permission, from Jenkins, R., An Introduction to X-ray Spectrometry, p. 28, Heyden, London, 1976)...

Fig.l, Emission spectrum from dithionite reduced chromatophores at 4.2 K in glycerol/water at pH7. Maximum at 1065 + 1 nm. Emission intensity in arbitrary units. 

Eckstein, J. W., et al. (1990). A time-dependent bacterial bioluminescence emission spectrum in an in vitro single turnover system energy transfer alone cannot account for the yellow emission of Vibrio fischeri Y-l. Proc. Natl. Acad. Sci. USA 87 1466-1470. 

Figure 1. Average corrected emission spectrum (- -) and excitation spectrum (- -) for quinine sulfate In 0.1 mol/L HC10 obtained during round-robin test with ten laboratories coefficient of variation at each wavelength (-t).

The emission spectrum has been reported only for l.41 A plot of the absorption, emission, and excitation spectra for 1 is shown in Fig. 1. 

As mentioned previously, the complex emission spectrum F (l) of samples containing multiple fluorophores is assumed to be the linear sum of individual component spectra Ffl), F2(X), FfX), weighted by their abundance xu x2, x3. Let Fj(X) and F2(X) be the reference emission spectra of pure samples of fluorophore (e.g., Cerulean and Venus). The term reference emission spectra is used because these spectra describe the emission at excitation wavelength /. x of a defined concentration of fluorophore (e.g., 10 /rM) acquired using the same excitation light intensity as was used to acquire an emission spectra of an unknown sample mixture. Under these conditions, the shape and magnitude of the fluorophore mixture spectra will be ... 

In Eq. (4.5) the donor emission spectrum/ and the acceptor absorption spectrum eA are separately normalized to unity, so that the transfer rate is independent of the oscillator strength of either transition. Unfortunately, the constants W and L are not easily determined by experiment. Nevertheless, an exponential dependence on the distance is expected. It should be noted that this type of transfer involves extensive orbital overlap and is guided by Wigner s (1927) spin rule. 

There is a small solvent dependence for [Ru(L)3]2+complexes which depends on the structure of L. The emission spectra of the Ru(bpy)32+ is mildly sensitive to media, the Ru(phen)32+ much less so, and the Ru(Ph2phen)32+ is virtually media independent. This decreasing sensitivity to solvent perturbation is a consequence of the excitation being localized in the metal a-diimine portion of the complex (-N=C-C=N).(27) The more extended the complex, the greater the shielding of the excited portion and the smaller the solvent perturbations of the emission spectrum. In particular, the bulky phenyl groups are extremely effective at shielding the excited state from environmental perturbations. 

Fig. 10. (A) Structure and (B) fluorescence emission spectrum of Tb-[N-2-pyridylmethyl)-N, N",N" -tris(methylenephosphonic acid butyl ester)-l,4,7,10-tetraazacyclododecane] (Tb-PCTMB). Reprinted with permission from [126], Copyright 1999 American Chemical Society...

The phosphine-functionalized tpy ligand 4 -Ph2Ptpy has both hard and soft donor sites the ligand is prone to oxidation to 4 -Ph2P(0)tpy and this affects the method of preparation of [Ru(4 -Ph2Ptpy)2]. " The complex [RuL(4,4 -Me2bpy)(NCS)] where L = 4-phosphonato-2,2 6, 2"-terpyridine, shows two ground-state pKi values at 6.0 and <4.0. The emission spectrum of the complex and the excited-state lifetimes are pFI-dependent. ... 

A convenient method is the spectrometric determination of Li in aqueous solution by atomic absorption spectrometry (AAS), using an acetylene flame—the most common technique for this analyte. The instrument has an emission lamp containing Li, and one of the spectral lines of the emission spectrum is chosen, according to the concentration of the sample, as shown in Table 2. The solution is fed by a nebuhzer into the flame and the absorption caused by the Li atoms in the sample is recorded and converted to a concentration aided by a calibration standard. Possible interference can be expected from alkali metal atoms, for example, airborne trace impurities, that ionize in the flame. These effects are canceled by adding 2000 mg of K per hter of sample matrix. The method covers a wide range of concentrations, from trace analysis at about 20 xg L to brines at about 32 g L as summarized in Table 2. Organic samples have to be mineralized and the inorganic residue dissolved in water. The AAS method for determination of Li in biomedical applications has been reviewed . 

Fig. 17 Ratio of third to first vibrational peak of pyrene emission spectrum as a function of DTAB concentration in the presence of 1 g/L sodium polyacrylate...

Both compounds crystallize with the cadmium diiodide structure (space group P3ml) as previously reported on polycrystalline samples.3 For platinum disulfide, ao = 3.542(1) A and c0 = 5.043(1) A, and for platinum ditelluride, a0 = 4.023(1) A and c0 = 5.220(3) A. Direct chemical analysis for the component elements was not carried out. Instead, precision density and unit-cell determinations were performed to characterize the samples. The densities of both compounds as determined by a hydrostatic technique with heptadecafluorodeca-hydro-l-(trifluoromethyl)naphthalene as the density fluid4 indicated that they are slightly deficient in platinum. For platinum disulfide, = 7.86 g/cm3 and Pmeas = 7.7(1) gm/cm3, and for platinum ditelluride, p = 10.2 gm/cm3 and Pmeas = 9.8(1) gm/cm3. In a typical experiment an emission spectrum of the platinum disulfide showed that phosphorus was present in less than 5 ppm. A mass spectroscopic examination of the platinum ditelluride revealed a small doping by sulfur (less than 0.4%) and traces of chlorine and phosphorus (less than 100 ppm). 

Figure 2 X-ray emission spectrum for "(Bi,Pb)2Sr2Ca2CusO10" showing overlap of Pb and B L lines...

Forbes, P. D., R. E. Davies, L. C. D Aloisio, and C. Cole, Emission Spectrum Differences in Fluorescent Blacklight Lamps, Pho-tochem. Photobiol., 24, 613-615 (1976). 

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