Quaternary diffusion in aqueous potassium chloride-potassium dihydrogen phosphate-phosphoric acid mixtures

Abstract

anion substantially enhances the production of MV,+ sensitized by Eosin Y.31 Eosin Y is a heavy-atom-substituted xanthene dye (tetrabromofluorescein), for which the internal heavy-atom effect would be expected to reduce the cage escape yield by increasing the singlet -* triplet or back-electron-transfer rates within the solvent cage. Similarly, Edel et al. report a very large enhancement of MV*+ when anthracenecarboxylate acts as a shuttle for a copper(I) complex.9 Their data indicate that the anthracene shuttle causes an enhancement of greater than 60-fold in MV'+ production, indicating that the cage escape yield for the [Cu complex, MV+] pair is <0.02. This suggests a rapid rate of back-electron-transfer within the solvent cage, which in turn can (31) Mau, A. W.-H.; Johansen, O.; Sasse, W. H. F. Photochem. Photobiol. 1985, 41, 503. be attributed to paramagnetism and rapid spin interconversion at the copper complex. A similar explanation was also proposed for the very low yields of charge pairs in the CuTPP-benzoquinone system.13Acknowledgment. This research was supported by a grant from the National Science Foundation, Grant No. CHE-8503092. J.O. thanks the California State University, Fullerton, for providing a sabbatical leave and the University of North Carolina at Chapel Hill for a visiting appointment for the time during which this work was accomplished.

Cross-diffusion and pattern formation in reaction–diffusion systems

“…57,58 They used optical interferometry, Gouy and Rayleigh methods. 59,60 Other approaches, like the diaphragm-cell technique [61][62][63] and the Taylor method [64][65][66][67] have also been adapted to measure cross-diffusion coefficients. The Taylor method, which we discuss below, is probably the most widely employed technique at present.…”

“…Thus far we have considered the role of cross-diffusion only in linear, monomolecular reactions. Consider now the more complex but more common case of bimolecular reactions of the general form A + S 2 B + P (62) with forward and reverse rate constants k 1 and k 2 , respectively. As we did for reaction (33), we can seek the condition for Turing instability in this equilibrium reaction by applying linear stability analysis.…”

“…If only D 12 a 0 and all other off-diagonal elements of D are zero, then linear stability analysis gives the condition for Turing instability as To obtain Turing patterns in a system described by reaction (62), the coefficient D 13 must be negative or the coefficient D 12 positive. Intuitively, positive D 12 reduces the concentration of S at the site of a positive perturbation of A at x = x 0 (opposite of the situation shown in Fig.…”

Relating multicomponent mutual diffusion and intradiffusion for associating solutes. Application to coupled diffusion in water-in-oil microemulsions

“…In fact, D ik coefficients are available for only a handful of four-component or higher-order systems. 29,34,[47][48][49] Intradiffusion measurements for many-component solutions, on the other hand, can be relatively convenient if suitable magnetic resonances or radioactive labels are available. It would be useful, therefore, to develop procedures for the evaluation of multicomponent mutual diffusion coefficients from the more readily available intradiffusion coefficients.…”

Thermal diffusion of weak electrolytes: aqueous phosphoric and iodic acids

“…This simplification is supported by the observation that the limiting slope dH */dl 'I2 agrees qualitatively with the value -10.8 kl kg1'' m~l -~'~ expected for a simple 1: 1 electrolyte (1 1). Moreover, previously measured (27) isothermal diffusion coefficients of aqueous KH2P04 extrapolate co~~ectly to the limiting Nernst value for a strong 1 : 1 electrolyte.…”