Radiochemical studies of ion-exchange

The first part of the work described in this thesis deals with the preparation of uniformly thin sources suitable for the counting of weak β-emitting radioisotopes. The method developed involved the preparation of a thin sulphonated polystyrene layer supported on a thin VYNS film on which cations were deposited by ion-exchange. The p-counting efficiency of the sources in a 4 II β-proportional counter was determined by coincidence counting. Autoradiography was used to determine the uniformity of the sources. Evaporated gold on the VYNS film support was found to promote the surface diffusion of mercury and investigations led to a procedure applicable to the measurement of the counting efficiency of p-emitting mercury isotopes; a method for the calibration of a proportional counter used in the determination of the Tl(^203)(n,pHg(^203) cross-section was thereby evolved. In Part II preliminary experiments were directed towards finding a suitable "liquid ion exchanger" for an investigation of ion-exchange behaviour, particularly at high electrolyte concentrations; mono-(2-ethylhexyl) phosphoric acid (H(_2)MEHP) in toluene was eventually selected.