Triplet-state energies determination

The triplet-state energy level of oxytetracycline, the excitation maximum (412 nm), lifetimes of Eu-OxTc (58 p.s) and Eu-OxTc-Cit (158 p.s), were determined. A 25-fold luminescence enhancement at 615 nm occurs upon addition of citrate within a short 5-min incubation time at neutral pH. It s accompanied by a threefold increase of the luminescence decay time. The optimal conditions for determination of OxTc are equal concentrations of Eu(III) and citrate (C = T lO mol-E ), pH 7.2. Eor determination of citrate, the optimal conditions concentrations of Eu(HI) and OxTc are 1 0,5 (Cg = MO Huol-E-i, = 5-10-HuohE-i) at pH 7.2. 

Rios, A. de O., A. Z. Mercadante, and C. D. Borsarelli. 2007. Triplet state energy of the carotenoid bixin determined by photoacoustic calorimetry. Dyes Pigments 74 561-565. 

Transfer of Triplet State Energy in Fluid Solutions I. Sensitized Phosphorescence and Its Application to the Determination of Triplet State Lifetimes. Acta Chem. Scand. 14, 48 (1960). 

Goez and Frisch have used photo-CIDNP to measure the activation energy of a biradical rearrangement reaction. Roth ° has studied the electron transfer back reactions of photoexcited cis- and trans-1,2-diphenylcyclopropane in the presence of singlet acceptors. He finds that the pair energy relative to the reactant ground states and an accessible triplet state, respectively, determines whether the back reaction is competitive. 

Backstrdm HLJ, Sandros K (1960) Transfer of triplet-state energy in fluid solutions. I. Sensitized phosphorescence and its application to the determination of triplet-state lifetimes. Acta Chem Scand 14 48-62... 

The long triplet lifetimes are attributed to reversible triplet energy transfer with the appended pyrene moieties and, using ultrafast transient absorption spectroscopy, the rates of formation of the equilibrium distribution of triplet states were determined [188]. 

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