Lasers time-resolved laser-induced fluorescence

The hydrolysis of the uranyl(VI) ion, UO " 2> has been studied extensively and begins at about pH 3. In solutions containing less than lO " M uranium, the first hydrolysis product is the monomeric U02(OH)", as confirmed using time-resolved laser induced fluorescence spectroscopy. At higher uranium concentrations, it is accepted that polymeric U(VI) species are predominant in solution, and the first hydrolysis product is then the dimer, (U02)2(0H) " 2 (154,170). Further hydrolysis products include the trimeric uranyl hydroxide complexes (U02)3(0H) " 4 and (1102)3(OH)(154). At higher pH, hydrous uranyl hydroxide precipitate is the stable species (171). In studying the sol-gel U02-ceramic fuel process, O nmr was used to observe the formation of a trimeric hydrolysis product, ((U02)3( -l3-0)(p.2-0H)3) which then condenses into polymeric layers of a gel based on the... 

Thouvenot P, Hubert S, Moulin C, et al. 1993. Americium trace determination in aqueous and solid matrices by time-resolved laser-induced fluorescence. Radiochim Acta 61 15-21. 

Bublitz [62] used time resolved laser induced fluorescence spectroscopy and fibre optics to determine polyaromatic hydrocarbons in oil polluted soils. The detection limit was 5mg kgy1 oil in soil. 

Gabriel, U., Charlet, L., Schlapfer, C. W., Vial, J. C., Brachmann, A. Geipel, G. 2001. Uranyl surface speciation on silica particles studied by time-resolved laser-induced fluorescence spectroscopy. Journal of Colloid and Interface Science, 239, 358-368. 

Conventional analytical techniques generally operate at the part per million or higher levels. Some techniques such as laser photo acoustic spectroscopy are capable of measuring phenomena at the 10-8-10-6 mol/L level. The most sensitive conventional analytical techniques, time-resolved laser-induced fluorescence, and ICP-MS are capable of measuring concentrations at the part per trillion level, that is, 1 part in 1012, but rarely does one see detection sensitivities at the single atom level as routinely found in some radioanalytical techniques. While techniques such as ICP-MS are replacing the use of neutron activation analysis in the routine measurement of part per billion concentrations, there can be no doubt about the unique sensitivity associated with radioanalytical methods. 

The radiative lifetimes of many excited states of Li,16 Na,17-21K,22 Rb,23-25 and Cs,26-28 have been measured using a variety of techniques, the most common being time resolved laser induced fluorescence, which is typically carried out using a cell, as shown in Fig. 4.4. In all cases, the observed lifetimes are in reasonable agreement with values calculated in the coulomb approximation, corrected for the decrease due to black body radiation.29 In the following chapter we show that if the 0 K lifetime of a state is r that its lifetime at a finite temperature T is given by24 30... 

CLM method can also be combined with various kinds of spectroscopic methods. Fluorescence lifetime of an interfacially adsorbed zinc-tetra-phenylporphyrin complex was observed by a nanosecond time-resolved laser induced fluorescence method [25]. Microscopic resonance Raman spectrometry was also combined with the CLM. This combination was highly advantageous to measure the concentration profile at the interface and a bulk phase [14]. Furthermore, circular dichroic spectra of the liquid-liquid interface in the CLM could be measured [19]. 

Figure 3. Effect of metal concentration on the interaction constant of trivalent actinides with Aldrich humic acids (at a ionic strength of O.IM). TRLIF Time-Resolved Laser-Induced Fluorescence, SP Spectrophotometry.

Ashjian, P., Elbarbary, A., Zuk, P., DeUgrate, D.A., Benhaim, P., Marcu, L. and Hedrick, M.H. (2004) Noninvasive in situ evaluation of osteogenic differentiation by time-resolved laser-induced fluorescence spectroscopy. 

Time resolved laser induced fluorescence spectroscopy has been successfully applied to study sorption of Cm(IIl) on silica in situ [40]. Peak deconvolution of the... 

Time differential perturbed angular correlation spectroscopy, 353 Time, dimensionless, 535 Time resolved laser induced fluorescence spectroscopy, 349, 350 Titanates... 

Time-Resolved Laser-Induced Fluorescence Characterization of Uranium Complexes and Processes in ScF CO2... 

L. Marcu, W.S. Grundfest, M.C. Fishbein, Time-resolved laser-induced fluorescence spectrocopy for staging atherosclecotic lesions, in M.-A. Mycek, B.W. Pogue (eds.), Handbook of Biomedical Fluorescence, Marcel Dekker Inc. New York, Basel, 397-430 (2003)... 

Miller, K. J., Leesong, 1., Bao, J., Regnier, RE., and Lytle, RE. ElectrophoreticaUy mediated microanalysis of leucine aminopeptidase in complex matrices using time-resolved laser-induced fluorescence detection. Ana/. Chem., 65, 3267, 1993. 

The uranium content in plants and mushrooms grown on a uranium-contaminated site in Germany was determined by ICPMS (Baumann et al. 2014). All samples were sent to the laboratory immediately after collection and processed there. First, the samples were rinsed with deionized water and then cut with a knife and separated into liquid sap and solid residue by centrifugation. Birch leaves were hacked by a food processor and centrifuged, but the amount of sap was not always sufficient for analysis. The residues were digested in a closed Teflon vessel in a microwave oven for half an hour. The uranium content in the sap and digested samples was determined by ICPMS. Some samples were also analyzed by time-resolved laser-induced fluorescence (TREES) in a He-cryostat that is suitable for speciation studies. 

TRLFS Time-resolved laser-induced fluorescence spectrometry (analyti-... 

In pesticide trace analysis, efforts have been made to observe directly the coupling of antigen-antibody in the quenching of the fluorophore bound to a tracer molecule, by the use of time-resolved. laser-induced fluorescence [31]. On formation of an Ag -AB complex, a significant change in the fluorescence lifetime is observed. However, the fluorescence quantum yield suffers drastically, and this test has never been used. 

I I R. Niessner el al. Application of Time-Resolved Laser-Induced Fluorescence for the Immunological Determination of Pesticides in the Water Cycle, in B. Hock,... 

Time-resolved laser-induced fluorescence experiments have demonstrated that the photodissociation of T-Ar is preceded by intramolecular vibrational redistribution (IVR) processes in which the pumped level C. develops into levels C of the complex which are not accessible by optical excitation because they include highly excited van der Waals vibrations. The isoenergetic levels C and C of the cluster are characterized by different vibronic states of the tetrazine moiety. 

Using space-time-resolved laser-induced fluorescence and plasma-induced emission spectroscopy, the interaction between BCI3 and Ar gives metastable and dissociation product densities that vary nonlinearly as Ar is diluted by BCI3. A model is proposed in which argon metastable states indirectly enhance molecular dissociation [7]. 

Fig. 9.20. Time-resolved laser-induced fluorescence recordings in a sequence of sulphur, employing the transient digitizer technique [9.122]...

RS Addleman, CM Wai. On-Line time-resolved laser-induced fluorescence of U02(N03)2 2TBP in supercritical fluid CO2. Anal Chem 72 2109-2116, 2000. 

RS Addleman, JW Hills, CM Wai. A high pressure flow cell for on-hne absorption, Raman, and time resolved laser induced fluorescence spectroscopy in supercritical fluids. Rev Sci Instrum 69(9) 3127-3131, 1998. 

Lifetimes x of 51 odd levels (taken from [17]) have been measured with an accuracy of 5% by the technique of time-resolved laser-induced fluorescence on an Ru atomic beam [11,12] and compared to earlier measurements [13], see Table 2/2. 

Using time resolved laser induced luminescence spectroscopy the relative yields of T-T Intra-ET and S-S Intra-ET were determined. Typical examples are shown in Figs. 3-6 where comparison is made between the relative quantum yields of fluorescence and phosphorescence of the o-diketone chromophore upon direct excitation of the a-diketone chromophore at 430 nm to that obtained by exciting the aromatic moiety at 266nm followed by S-S and T-T Intra-ET. The results indicate competition between T-T Intra-ET and S-S Intra-ET leading to a more efficient T-T process whenever S-S Intra-ET becomes less efficient. 

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