SOLVATED POSITRON CHEMISTRY .2. REACTION OF HYDRATED POSITRONS WITH CL-,BR- AND I- IONS

The reaction of the hydrated positron, eaq+ with Cl-, Br-, and I- ions in aqueous solutions was studied by means of positron The measured angular correlation curves for [Cl-, e+], [Br-, e+, and [I-, e+] bound states were in good agreement with th Because of this agreement and the fact that the calculated positron wavefunctions penetrate far outside the X- ions in the [X-, e+] sta propose that a bubble is formed around the [X-, e+] state, similar to the Ps bubble found in nearly all liquids. F-ions did not react w Preliminary results showed that CN- ions react with eaq+ while OH-ions are non reactive. The rate constants were 3.9 × 1010 M-1 s-1, 4.4 × 1010 M-1 s-1, and 6.3 × 1010 M-1 s-1 for Cl-, Br-, and I-, respectively, at low (≲ 0.03 M) X- concentrations. A 25% decrease in the rate constant caused by the addition of 1 M ethanol to the I- solutions was i The influence of halide ions on the positronium (Ps) yields in pure water was studied by use of lifetime measurements. The Cl-, Br-, and I- ions reduced the Ps yields at low concentrations (≲ 0.03 M), while F- ions only reduced the Ps-yield However, the Ps yields saturated (e.g. at ≈ 21% ortho-Ps yield in the Cl- case) at higher concentrations. This saturation and the high-concentration effects-in the angular correlation results were interpreted as caused by rather complicated spur effects, wh It is proposed that spur electrons may pick off the positron from the [X-, e+ states with an efficiency which depends on the structure of the. © 1979.