Induced Transients with First-Order Kinetics

LASER-INDUCED TRANSIENTS WITH FIRST-ORDER KINETICS 

Consider that the laser-induced potential change, A , contains two contributions  

Consider that the first contribution, AEi, is virtually instantaneous. Accordingly, AE will be given by the product of the temperature coefficient of this process, i, and the laser-induced temperature change, AT  

Consider that the second contribution follows ffist-order kinetic. Accordingly, the potential relaxation will be given by  

In conclusion, the laser-induced potential transient will be given by  

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A spectroscopic investigation of the formation of THF-Cu"Cl2 complexes has been described, and irradiation of [Cu(Dto)2] (Dto = dithiooxalate) has been found to induce an intramolecular Dto Cu two-electron transfer with cleavage of the C-C bond in the Dto ligand and the formation of SCO. The kinetics of photo-oxidation of pyrene by Cu" in SDS micelles have been measured, but oxidants such as Eu" and Hg do not produce pyrene cations. A non-exponential decay of fluorescence is observed, and this is interpreted in terms of a model due to Tachiya which restricts the numbers of quenchers in a micelle. Transient Cu"-alkyl species are formed on flash photolysis of Cu -bis(amino-acid) complexes such as those of serine and valine, and pseudo first order rate constants for the decay of the transients have been obtained. 

Competition experiments again feature prominently in another discussion of the possible role of transient five-coordinate [Co(NH3)5] in induced and in spontaneous aquation of pentaaminecobalt(III) derivatives. " The operation or nonoperation of the D mechanism at various cobalt(III) centers and at penta-cyanoferrate(II) still requires a few experiments providing unambiguous results. Its operation at molybdenum(O)- and tungsten(0)-penta or tetracarbonyl complexes seems more firmly based. The question of its operation at pentacyanoferrates(III) does not seem to have caused much concern. The only recent paper which mentions kinetics of such a reaction, replacement of 2-methyl imidazolate in [Fe "(CN)5(2-Meimid)] ", reports that the limiting first-order rate constant is 2.3 x 10 s at 298 K, but is more preoccupied with redox catalysis by traces of iron(II) than with simple substitution. 

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