Radiolysis transients in viscous liquids. Biphenyl in liquid paraffin

Fuller, Joan; Peteleski, N.; Ruppel, D.; Tomlinson, M.

doi:10.1021/j100710a008

Cited by 12 publications

(2 citation statements)

References 8 publications

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“…AE* = -R7 fin (12) ^= R7 Jd In t?\ l dP }t (13) The values of AE*S for MEA and DCNA and the values of £** for anthracene and MEA, calculated over a range of pressures, are summarized in Table 3, together with the values of AE* calculated from literature data33a'b using eqs 3 and 12.…”

Section: Dp 7t Rt ~' Dp > V Dp 'mentioning

confidence: 99%

Study of the Fractional Power Dependence on Solvent Viscosity of the Rate Constant for Bimolecular Diffusion-Influenced Quenching Reactions between Oxygen and the Singlet and Triplet States of Anthracene Derivatives

Hirayama¹,

Yasuda²,

Scully³

et al. 1994

J. Phys. Chem.

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The effect of solvent viscosity on the quenching by oxygen of S1 and T1 states was investigated for a number of meso-substituted anthracene derivatives. The solvent viscosity, r], was varied by applying hydrostatic pressure at several temperatures. The fluorescence from the S1 state of the anthracene derivatives that have one or two electron-donating substituents was quenched nearly collisionally, and the dependence of the rate constant for fluorescence quenching, kS, on r] was shown to be described satisfactorily by the empirical function, Aq". It was shown for 9-methylanhracene in methylcyclohexane that the exponent, a, has a value of 0.68 f 0.06, which is independent of temperature and pressure but that thevalue of the constant of proportionality, A, is temperature dependent. The dependence of A on temperature was described empirically using the functions P.36 or exp(-AEIRT). An alternative function for is (T/r])@, but this function failed to describe correctly the dependence of kt on 9 and T. The fractional power dependence of k: on 4 suggests that the rate constant for the intrinsic fluorescence quenching reaction, kaCt, is not significantly larger than the rate constant for diffusion.The values of k: for the anthracene derivatives containing one or two electron-attracting substituents were smaller than that found for anthracene, decreased with Hammett's up parameter, and could not be described by the empirical function A?* with a constant value for a. A typical example is 9,lO-dicyanoanthracene whose values for k: exhibit a convex dependence on In r]. In accordance with this, the activation energy associated with k: was negative at low viscosities and displayed a transition from negative to positive values as the viscosity was increased. The values of the rate constant for the quenching by oxygen of the T1 states of the anthracene derivatives, k t , did not vary significantly, all being approximately 3 X lo9 M-1 s-l at 25 OC and 0.1 MPa. The logarithmic values of k;, when plotted as a function of In r], displayed appreciable downward curvature for all of the anthracene derivatives examined in this work.

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Section: Dp 7t Rt ~' Dp > V Dp 'mentioning

confidence: 99%

Study of the Fractional Power Dependence on Solvent Viscosity of the Rate Constant for Bimolecular Diffusion-Influenced Quenching Reactions between Oxygen and the Singlet and Triplet States of Anthracene Derivatives

Hirayama¹,

Yasuda²,

Scully³

et al. 1994

J. Phys. Chem.

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“…Furthermore, the effects of triplet-triplet annihilation can be shown to be negligible because the decay of related triplets in the viscous solvent, liquid paraffin, decay by a predominantly first-order process which has little or no second-order contribution. 28 In benzene solutions, the fluorene fluorescence is not affected by an applied magnetic field either in pulse or continuous radiolysis with a small y source. 7 Therefore the fluorescence lifetime, the fluorescence decay time, and the fluorescence efficiency are not changed by a magnetic field and, assuming the same to hold in squalane, the fluorescence observed in our system after the pulse is justifiably attributed solely to ion recombination.…”

Section: Discussion Of Resultsmentioning

confidence: 99%

Pulse radiolysis in an applied magnetic field. The time dependence of the magnetic field enhancement of the fluorescence from solutions of fluorene in squalane

Sargent¹,

Brocklehurst²,

Dixon³

et al. 1977

J. Phys. Chem.

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Publication costs assisted by Atomic Energy of Canada Limited The effect of a magnetic field on the light emission from squalane solutions of fluorene, pulse irradiated at the center of a large electromagnet, is described. The fluorescence intensity following pulse radiolysis was found to be 40-50% higher in an applied field of 0.3 T (3000 G) and the triplet yield showed a small decrease. The enhancement of the singlet emission is attributed to an increase in the fraction of geminate solute ion recombinations leading to excited singlet fluorene. The magnetic field effect was time dependent, being undetectable during the pulse and reaching a maximum value after about 100 ns. These observations are compared with the theory of Brocklehurst which describes the singlet to triplet conversion of geminate solute ion pairs quantitatively in terms of the electron-nuclear hyperfine interactions in the radical ions. After correction for the large in-pulse fluorescence and its decay, satisfactory agreement between experiment and theory was obtained.The results emphasize the importance of ion recombination in the generation of excited states in radiolysis and confirm the role of the electron-nuclear spin interaction in determining the ratio of Ringlet and triplet yields.

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Photoreduction of IrCl62? complex in alcohol solutions and its reaction with hydroxyalkyl radicals

Glebov

Plyusnin

Grivin

et al. 1998

Int. J. Chem. Kinet.

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The photochemistry of complex in simple alcohols have been studied using 2ϪIrCl 6 laser-flash photolysis. Single electron transfer from the solvent molecule to the light-excited complex has been shown to be the primary photochemical process. Quantum yields of the photoreduction of complex and the rate constants of its reaction with hydroxyalkyl 2ϪIrCl 6 radicals were determined at Deviations of the rate constants from Debye-Smo-200-330 K. luchowski equation for diffusion-controlled reactions are discussed.

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Radiolysis transients in viscous liquids. Biphenyl in liquid paraffin

Cited by 12 publications

References 8 publications

Study of the Fractional Power Dependence on Solvent Viscosity of the Rate Constant for Bimolecular Diffusion-Influenced Quenching Reactions between Oxygen and the Singlet and Triplet States of Anthracene Derivatives

Study of the Fractional Power Dependence on Solvent Viscosity of the Rate Constant for Bimolecular Diffusion-Influenced Quenching Reactions between Oxygen and the Singlet and Triplet States of Anthracene Derivatives

Pulse radiolysis in an applied magnetic field. The time dependence of the magnetic field enhancement of the fluorescence from solutions of fluorene in squalane

Photoreduction of IrCl62? complex in alcohol solutions and its reaction with hydroxyalkyl radicals

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