Angular Correlation of Annihilation Photons in Frozen Aqueous Solutions

Linear‐slit angular correlation curves were obtained at about $\text{−140°}\mathrm{C}$ for frozen aqueous solutions of HF, HCl, HBr, HI, NH₃, FeCl₂, FeCl₃, NaI, H₂SO₄, NHO₃, MnSO₄, KMnO₄, K₂Cr₂O₇, NaOH, and LiOH. We found no appreciable influence of a 4% concentration of the last seven impurities. Only halide‐containing impurities strongly changed the form of the curves; ppm concentrations of HCl and HF could be seen. The main change was a broadening of the part of the curve where the narrow and broad components meet. This fact is interpreted as being caused by trapping of para‐positronium in holes in the structure created by the impurities. No evidence of any chemical reactions of positronium and the impurities was found. The annealing of a fast frozen FeCl₂ solution was studied. The strongest changes in the curves occurred on annealing from $\text{−136}$ to $\text{−100°}\mathrm{C}$ .