On the temperature dependence of the primary yield and the product G[[epsilon].sub.max] of hydrated electrons in the low-LET radiolysis of liquid water

Citation metadata

From: Canadian Journal of Chemistry(Vol. 80, Issue 7)
Publisher: NRC Research Press
Document Type: Author abstract
Length: 269 words

Document controls

Main content

Abstract :

Monte-Carlo simulations are performed to calculate the temperature dependence of the primary hydrated electron yield ([G.sub.e.sup.-.sub. aq]) for liquid water irradiated by low linear-energy-transfer radiation (LET ~ 0.3 keV [[micro]m.sup.-1]) in the range 25-325[degrees]C. Calculations are carried out by taking properly into account the effect of the time and temperature dependencies of the water dielectric constant on the electron-cation geminate recombination. Our computed [G.sub.e.sup.-.sub.aq] values slightly increase with increasing temperature, in good agreement with experiment. The product [G.sub.e.sup.-.sub.aq][[epsilon].sub.max] ([e.sup.-.sub.aq]), estimated by using existing experimental data of the maximum molar extinction coefficient [[epsilon].sub.max] ([e.sup.-.sub.aq]), remains nearly constant or slightly increases, depending on the temperature dependence chosen for [[epsilon].sub.max]. Our [G.sub.e.sup.-.sub.aq][[epsilon].sub.max]([e.sup.-.sub.aq]) values compare generally well with most experimental data, as well as with the predictions of deterministic diffusion-kinetic model calculations. Moreover, our results indicate that the static dielectric constant of water ([[epsilon].sub.s]) does not play any significant role on the electron-cation recombination at early times. Such a finding is inconsistent with the interpretation, proposed by certain authors in the literature, that [G.sub.e.sup.-.sub.aq] should in fact decrease as temperature is increased because of an increased electron-cation geminate recombination due to a lowering of [[epsilon].sub.s]. Finally, the temperature dependence of the hydrated electron yields, calculated at various times between 10 ps and 1 [micro]s, shows that at low LET, the time required to establish homogeneous chemistry in the bulk of the solution is ~[10.sup.-6] s in the range ~25-100[degrees]C, and that this time diminishes to ~[10.sup.-7] s at higher temperatures. Key words: liquid water, radiolysis, temperature, hydrated electron ([e.sup.-.sub.aq]), radiolytic yields, electron-cation geminate recombination, dielectric constant, molar extinction coefficient of [e.sup.-.sub.aq], homogenization time.

Source Citation

Source Citation   

Gale Document Number: GALE|A109130866