The scavenging of the precursors of the solvated electrons fom the positron lifetime spectroscopy and the Doppler broadening of annihilation line shape technique

The electron scavenging properties in water of two series of solutes are investigated, using the positron as a probe. For a better interpretation of the data, both the lifetime specroscopy and the Doppler broadening of annihilation line shape technique are used. All solutes inhibit the positronium (Ps) formation, by the scavenging of electron. The first series consists of the halate ions, that should follow the Hunt linear relation between the rate constant for reaction with the solvated electrons, ksub(e-sub(aq)+S) and that for its precursors(s), 1/C37. The Ps inhibition constants, k, are 0.14, 1.44 and 3.45M-1 for ClO3- , BrO3- and IO3- respectively. This sequence is quantitatively consistent with that of the respective ksub(e-sub(aq)+S). The second series includes the SeO4--, Te(OH)6 and BrO4- species, and the Ps inhibition constants are 5.62, 10.5 and 14.3 respectively. Theses values are much higher than expected from the ksub(e-sub(aq)+S) constants, on basis of the Hunt relation, in agreement with previous results from pulse radiolysis experiments