Spectral kinetics

Ramanujan, V. K., Biener-Ramanujan, E., Armmer, K., Centonze, V. E. and Herman, B. A. (2006). Spectral kinetics ratiometry A simple approach for real-time monitoring of fluorophore distributions in living cells. Cytometry A 69, 912-9. 

Rationalise the spectral, kinetic and scavenging effects in terms of the production of Table 3.5). 

In this report the TTA process has been studied taking into account new experimental data indicating that the ADF emitted from metalloporphyrin upper electronic states is of dimeric nature. Moreover low values of P2 obtained in (6) can be explained by the lesser probability of dimer singlet staTes emitting in comparison with the monomer. But true probabilities of Sp state formation from TTA processes may be quite high. We have been able to establish simultaneous relations between diffusion parameters and annihilation characteristics obtained from spectral kinetic measurements. 

A narrow band with a main shoulder at 302 nm with a very short decay time of Ri 25 ns, and another with shoulders at 330 and 360 nm with a longer decay of 75 ns (Fig. 4.31c,d) in time-resolved spectra have spectral-kinetic... 

The spectral-kinetic parameters of the narrow band at 375 nm enable its confident identification as Eu + luminescence, which is confirmed by emission of synthetic BaS04 artificially activated by Eu (Fig. 5.15a). Such emission was also detected and interpreted by steady-state spectroscopy (Tarashchan 1978). It is interesting to note that very often such a band is absent in natural barite and appears only after heating in air at 600-700 °C (Fig. 4.31b). Such a transformation is reversible, at least partly. Under X-ray excitation the intensity of the UV band diminishes, and a new blue-green emission appears (Fig. 5.16). This shows some kind of transformation, which takes place in the barite lattice under these conditions. Several possibihties exist. It is possible that in barite the luminescence is quenched by the components with high-energy phonons. The water and organic matter may represent the latter. They are removed after... 

The spectral-kinetic parameters of the green laser-induced luminescence of the sedimentary apatites allow its association with emission. The spectra... 

According to spectral-kinetic parameters, the optimal conditions of luminescence excitation and detection, so called selection window (SW) parameters, were calculated in the following way. At optimal for the useful component excitation, the liuninescence spectra, decay time and intensity were determined for this mineral and for the host rock. After that, on the personal computer was calculated the proportion between useful and background signals for the full spectral region for each 50 ns after laser impulse. For calculation the spectral band was simulated by the normal distribution and the decay curve by the mono-exponential function. The useful intensity was multiplied by the weight coefficient, which corresponds to the concentration at which this component must be detected. 

Moderate enantioselectivity factors have also been found for electron transfer reactions between HRP or GO and resolved octahedral ruthenium or osmium complexes, respectively. In particular, the rate constants for the oxidation of GO(red) by electrochemically generated and enantiomers of [Os(4,4 - 2 ) ]3 + equal 1.68 x 106 and 2.34 x 106 M-1 s-1, respectively (25 °C, pH 7) (41). The spectral kinetic study of the HRP-catalyzed oxidation of and A isomers of the cyclo-ruthenated complex [Ru(phpy)(phen)2]PF6 (Pig. 21) by hydrogen peroxide has revealed similarities with the oxidation of planar chiral 2-methylferrocene carboxlic acid (211). In both cases the stereoseleci-vity factor is pH dependent and the highest factors are not observed at the highest rates. The kA/kA ratio for [Ru(phpy)(phen)2]PF6 is close to 1 at pH 5-6.5 but increases to 2.5 at pH around 8 (211). 

It has been observed that the concentrated solution viscosity decreases upon addition of TMEDA to solutions of poly(isoprenyl)lithium 93). This would be consistent with the process shown in Eq. (17) or (20) and not with Eqs, (18) or (19). The decrease in viscosity would be consistent with interaction of TMEDA to form an unassociated complex (Eq. (20)), but this does not seem to be in accord /with the stoichiometry observed by calorimetry. It is noteworthy that the break observed by calorimetry at R = 0.5 is consistent with the stoichiometric dependence of spectral, kinetic and microstructure effects 90). Again this shows that these kinetic effects are related to the stoichiometry of formation of base-organolithium adduct, i.e. that they are ground-state solvation effects. 

In chapter 7, special emphasis has been placed on the synthesis of representative polycyclic quinones and their photochromic behavior, including the spectral, kinetic, and fatigue characteristics of such systems. Potential applications are focused on recording and multiplication of images, optical memories, and gradation masking. 

The spectral-kinetic method has been proposed for studying ligand exchange rates [130], Consider the case of Eu(III) and the spectroscopic excited state is 5Do and this state is selectively excited by a pulsed dye laser. Let us consider the equilibrium... 

Korzeniowska-Sobczuk A, Hug GL, Carmichael I, Bobrowski K. (2002) Spectral, kinetics, and theoretical studies of radical cations derived from thioanisole and its carboxylic derivative./Pfryr Chem A 106 9251-9260. 

M. Wikstrom and J.E. Morgan. 1992. The dioxygen cycle Spectral, kinetic, and thermodynamic characteristics of ferryl and peroxy intermediates observed by reversal of the cytochrome oxidase reaction J. Biol. Chem. 267 10266-10273. (PubMed)... 

De Panafieu also measured the spectral kinetic response on KN3 single crystals (Figure 28). Photodecomposition of a previously unirradiated crystal started at about 3 eV but increased in the region of the (N3) band around 4.5 eV. In previously irradiated samples, decomposition also occurred at longer wavelengths in the Ni band around 800 nm. The results lend support to the theory that excited states of the azide anion lead to decomposition. It also shows that bleaching of the N4 leads to nitrogen evolution. 

Moderate enantioselectivity factors have also been found for electron transfer reactions between HRP or GO and resolved octahedral ruthenium or osmium complexes, respectively. In particular, the rate constants for the oxidation of GO(red) by electrochemically generated A and A enantiomers of [Os(4,4 -Me2bpy)3] equal 1.68 x 10 and 2.34 X 10 respectively (25 °C, pH 7) 41). The spectral kinetic... 

Such results reveal that upon electrochemical and enzymic (peroxidase) oxidation of uric acid and uric acid derivatives a uv-absorbing intermediate is formed. The spectral, kinetic, and electrochemical behavior of this intermediate whether generated enzymically or electrochemically are identical. Analytical data on the trapped and derivatized electrochemical intermediate are in accord with the uv-absorbing intermediate having an imine-alochol structure (i.e.. Ill, Figure 25). 

The mechanisms obtained in these enzyme studies are, in fact, based on rather insubstantial chemical evidence. However, by parallel investigation of the enzymic and electrochemical oxidations, signihcant mechanistic insights are obtained. Spectral, kinetic, and electrochemical information confirm that under both enzymic and electrochemical oxidation conditions the same uv-absorbing intermediate is formed upon oxidation of uric acid or its N-methy-lated derivatives. The GC/MS data on the trapped and derivatized intermediate generated electrochemically is that expected for the imine-alcohol struc-... 

Farges B, Laroche C, Comet JF, Dussap CG Spectral kinetic modeling and long-term behavior assessment of arthrospira platensis growth in photobioreactor imder red (620 nm) light fllumination, Biotechnol Prog 25(1) 151-162, 2009. 

Ermolaev VL, Gruzdev VP (1984) Novel spectral-kinetic method for investigation of ligand exchange in labile metal complexes in solutions. Inorg Chim Acta 95 179-185... 

Ritonavir is one of the most potent inhibitors of P450 3A4 [1416], A number of analogs have been compared using spectral, kinetic, and structural (ciystallography) approaches [1409, 1410, 1433],... 

A narrow band with a main shoulder at 302 nm with a very short decay time of 25 ns, and another with shoulders at 330 and 360 nm with a longer decay of 75 ns (Fig. 4.74c, d) in time-resolved spectra have spectral-kinetic parameters suitable for Ce " ". It is known that narrow bands near 300 nm are especially strong in (Ba,Sr)S04 (baritocelestine), while in barite they are situated at a longer wavelength (Gaft et al. 1985). The ionic radius of Ce + is 128 pm and a possible accommodation is isomorphic substitution for Ba (156 pm) or Sr " " (140 pm). Thus, two types of Ce " " centers may be connected with Sr impurity, the presence of which in barite samples is confirmed by ICP analysis (450-720 ppm). Luminescence of Ce in anhydrite is seen under excitation at 266 nm (Fig. 4.30b) and it is... 

The spectral-kinetic parameters of the narrow band at 375 nm enable its confident identification as Eu " " luminescence, which is confirmed by emission of synthetic BaS04 artificially activated by Eu (Fig. 5.17a). Such emission was also detected and interpreted by steady-state spectroscopy (Tarashchan 1978). It is interesting to note that very often such band is absent in natural barite and appears only... 

The spectral-kinetic parameters of the green laser-induced luminescence of the sedimentary apatites allow its association with 1102 " emission. The spectra presented in Fig. 4.5b, c are typical for uranyl minerals and it is possible to suppose that we are dealing with separate uranyl mineral phase on the apatite surface. Comparison with known uranyl minerals laser-induced luminescence shows that the most similar spectral-kinetic parameters have minerals andersonite Na2Ca (U02)(C03)3 X 6H2O and liebigite Na2(U02)(C03)3.10H20, but this identification is ambiguous. 

The luminescence properties of 82 centers correspond well to the spectral-kinetic characteristics of the stmctured yellow-orange spectra observed in time-resolved spectra of sodalite, tugtupite (Fig. 5.103), hackmanite (Fig. 5.104) (Gaftet al. 2009) and lasurite (Fig. 5.105). Molecules of 82 are unstable in the free-state, but become stabilized in a crystal lattice. 8ulfur substitutes for Cl atoms in the tugtupite and sodalite structures, and are surrounded by four Na atoms (Tarashchan 1978). Luminescence spectra of 82 have vibrational structure due to symmetric vibrations of sulfur atoms in the molecules. Quite the contrary, the excitation spectrum of sodalite and tugtupite luminescence is structureless at room and low temperatures. Thus the vibrational sublevels of the ground state are not stable and do not actively... 

Measurements of entrainment bands and similar dynamic features are examples of what we call spectral kinetics, the response of a complex kinetic system far from equilibrium to external periodic perturbations. There is an interesting analogy with optical spectroscopy. The structure of a... 

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