Picosecond pulse radiolysis studies on geminate ion recombination in saturated hydrocarbon

doi:10.1016/0146-5724(83)90128-0

Radiation Physics and Chemistry (1977)

Volume 21, Issues 1–2, 1983, Pages 45-52

https://doi.org/10.1016/0146-5724(83)90128-0 Get rights and content

Abstract

The geminate recombination kinetics of the excess electron and the electron hole are discussed, based on time-resolved data on picosecond and nanosecond time scales.

The recombination times of the excess electron and the electron hole are evaluated to be 3 ps for cyclohexane on the basis of the comparison between the experimental and the calculated results.

The spin correlation decay of the geminate ion pairs and the triplet state formation before the spin correlation loss have also been discussed.

The rapidly decaying species with very broad absorption spectra, which are similar to the absorption spectra of the cation radicals of saturated hydrocarbons, have been observed in neat saturated hydrocarbons in the sub-nanosecond and a few nanosecond time regions. The identification of the rapidly decaying species were not definitely made but those species are tentatively assigned to the excited states and/or the tail of the geminate cation radicals of saturated hydrocarbons.

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The kinetics of geminate ion recombination was studied by the femtosecond pulse radiolysis of n-dodecane with biphenyl solution. The complicated biphenyl concentration-dependence behaviors of the transient absorptions at 800 nm are observed and elucidated with a Monte Carlo simulation of geminate recombination and charge transfer processes in the biphenyl-dodecane solution. The experimental data suggested the existence of n-dodecane excited radical cation in the radiolysis. It plays very important roles especially in the high-concentration solution. The reaction rate constant of the excited radical cation with biphenyl molecule was 3.5×10¹¹ dm³ mol⁻¹ s⁻¹, which is comparable with the reaction rate constant of the electron with biphenyl molecule. The contributions of the geminate ion recombination, the charge transfer reaction and the relaxation of the excited radical cation were obtained as a function of the biphenyl concentration.
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The primary process of radiation chemistry was studied by the femtosecond pulse radiolysis in n-dodecane. The time-dependent behavior of geminate ion recombination in n-dodecane was investigated in neat n-dodecane and the solutions containing electron and cation scavengers. The excited radical cation was found from analyzing the geminate process by the theoretical simulation based on the diffusion theory. The life time of the excited radical cation was 7 ps in n-dodecane. The reaction rate constant of the excited radical cation with the triethylamine (TEA) was 3.3×10¹¹ dm³ mol⁻¹ s⁻¹, which is one order higher than the normal diffusion rate constant. Although 74% of the excited radical cations are relaxed to the radical cation, the residual 26% are geminately recombined with electrons.
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Picosecond pulse radiolysis studies on geminate ion recombination in saturated hydrocarbon

Abstract

J. Phys. Chem.

Chem. Phys. Lett.

J. Chem. Phys.

Radiat. Phys. Chem.

Radiat. Res. Rev.

J. Phys. Chem.

Phys. Rev. Lett.

Can. J. Chem.

Adv. Radiat. Chem.

Adv. Chem.

J. Phys. Chem.

J. Phys. Chem.

J. Chem. Phys.

J. Chem. Phys.

J. Chem. Phys.

J. Chem. Phys.

J. Chem. Phys.

J. Chem. Phys.

J. Chem. Phys.

J. Chem. Phys.

J. Chem. Phys.

J. Chem. Phys.

J. Chem. Phys.

J. Chem. Phys.

J. Chem. Phys.

J. Chem. Phys.

Radiat. Phys. Chem.

Radiat. Phys. Chem.

Radiat. Phys. Chem.