Nanosecond pulse radiolysis studies.

Abstract

Nanosecond pulse radiolysis studies on the behaviour of ē aq at high concentrations as a preliminary to the investigation of ē aq* have shown that contrary to normal classical homogeneous kinetics the electron decays initially in a first order manner, moving into second order decay within about 100 nanoseconds after the electron pulse. Further investigations have shown that for a comparable time after the pulse the distribution of the absorbing species is not homogeneous thus rendering any classical kinetic interpretation invalid. Qualitative calculations on the duration of the inhomogeneity were performed and the experimental results are in reasonable agreement with their predictions, The first order decay that is observed is considered to be more than a random sequence of reactions and two possible models are tentatively proposed to account for these events. Comparisons are made between this work and others in which inhomogeneity undoubtedly accounts for the unusually fast bimolecular rate constants for the primary decay ē aq + ē aq → H₂ + 2OH ̄ aq The deuterated electron was investigated with similar conclusions. The rate constants evaluated from this work were: [ Formulas omitted ] and the bimolecular rate constant, determined in a homogeneous environment, is in good agreement with the accepted literature values for the probable reactions involving ē aq in our system.