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Time Dependent Yield of the Hydrated Electron and the Hydroxyl Radical in D2O: a Picosecond Pulse Radiolysis Study

Abstract

Picosecond pulse radiolysis measurements were performed in neat D2O and H2O in order to study the isotopic effect on the time-resolved yield of hydrated electron and hydroxyl radical. First, the absorption band of the hydrated electron in D2O, , is measured between 250 and 1500 nm. The molar absorption coefficient of the solvated electron spectrum in D2O was determined using the isosbestic point method by scavenging the solvated electron using methyl viologen. The amplitude and shape of the absorption spectrum of the hydrated electron in D2O are different from those previously reported in the literature. The maximum of hydrated electron in D2O absorption band is ca. 704 nm with a molar absorption coefficient of (22900 ± 500) L mol-1 cm-1. Based on this extinction coefficient, the radiolytic yield of just after the 7 ps electron pulse was determined to be (4.4 ± 0.2) × 10-7 mol J-1, which coincides with the one for in H2O. The time dependent radiolytic yield of was determined from few ps to 9.5 ns. To determine the OD• radical yield, the contribution of the solvated electron and of the transient species produced by the electron pulse in the windows of the fused silica optical cell were taken into account for the analysis of the transient absorption measurements at 260 nm. Therefore, an approprite experimental methodology is used for measuring low absorbance at two different wavelenths in ps pulse radiolysis. The yield of the radical OD• just after the 7 ps electron pulse was found to be (5.0 ± 0.2) × 10-7 mol J-1. In the spurs of ionization, the decay rate of is slower than , whereas the decay rate of OD• is similar to the one of OH•. The here established time dependent yield of the solvated electron and the hydroxyl radical provide the fundament for improving the models used for spur reaction simulations in heavy water mainely for CANDU reactor chemistry.

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Publication details

The article was received on 10 Apr 2018, accepted on 09 May 2018 and first published on 10 May 2018


Article type: Paper
DOI: 10.1039/C8CP02276C
Citation: Phys. Chem. Chem. Phys., 2018, Accepted Manuscript
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    Time Dependent Yield of the Hydrated Electron and the Hydroxyl Radical in D2O: a Picosecond Pulse Radiolysis Study

    F. wang, U. Schmidhammer, J. Larbre, Z. Zong, J. Marignier and M. Mostafavi, Phys. Chem. Chem. Phys., 2018, Accepted Manuscript , DOI: 10.1039/C8CP02276C

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