Speciation of surfaces of the electrodeposited thorium by methods of alpha spectrometry and secondary ion mass spectrometry

The samples with the natural thorium isotope of 232Th were prepared by electrodeposition on the stainless discs from the solution Th(NO3)4.12H2O with the use of solutions of Na2SO4, NaHSO4, KOH and (NH4)2(C2O4) by electric current of 0.75 A. The prepared discs were analyzed by two methods: alpha spectrometry a secondary ion mass spectrometry. The numbers of the registered impulses for 232Th obtained from the alpha spectrometry. Activity and surface's weight was calculated from the numbers of the registered impulses for 232Th. After that, alpha spectrometry discs were analyzed by TOF-SIMS IV which is installed in the International Laser Centre in Bratislava. The integral and normalized intensities of isotope of 232Th and intensities of ions of ThO+, ThOH+, ThO2H+, Th2O4H+, ThO2-, ThO3H-, ThH3O3- a ThN2O5H- were measured. The linear correlation is between surface's weights of Th and intensities of ions of Th+ from SIMS, however the correlation coefficient has relatively low value. With SIMS method we found out that oxidized and hydride forms of thorium are significantly represented in samples with electroplated thorium. (author)