Radiolytic yields of the hydrated electron from transient conductivity. Improved calculation of the hydrated electron diffusion coefficient and analysis of some diffusion-limited (e{sup -}){sub aq} reaction rates
- Argonne National Lab., IL (United States)
We report new high-precision measurements of the radiolytic yields (G values) of hydrated electron from pulse radiolysis of dilute H{sub 2}O and D{sub 2}O solutions with 15 MeV electrons in the 4-75{degree}C temperature range. Applied radiation dose was calibrated calorimetrically from the change in conductivity of a phosphate buffer solution. The hydrated electron yield was deduced from the yield of stable HCl product produced with various concentrations of methyl chloride scavenger in the presence of 2-propanol to scavenge H and OH radicals. The temperature dependence of yields was determined for solutions of 0.01 M 2-propanol and 0.12 M MeCl in both H{sub 2}O and D{sub 2}O. The results are described by (t in {degree}C) G{sub e}(H{sub 2}O) = 2.73 + 3.76 x 10{sup -3} (t - 25) and G{sub e}(D{sub 2}O) = 3.24 + 3.32 x 10{sup -3} (t - 25). By use of these revised yield measurements, previous experiments to determine the hydrated electron diffusion coefficient could be reanalyzed. The refined values differ only marginally from the original report. In a discussion, we apply electron transfer theory to examine which of the very fast reactions of hydrated electrons can be considered `diffusion limited`. It is shown that the effective reaction distance for (e{sup -}){sub aq} scavenging by nitrobenzene and oxygen changes with temperature as a result of the change in diffusion rate. 53 refs., 10 figs., 2 tabs.
- OSTI ID:
- 81309
- Journal Information:
- Journal of Physical Chemistry, Vol. 99, Issue 26; Other Information: PBD: 29 Jun 1995
- Country of Publication:
- United States
- Language:
- English
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