Charge Neutralization in Nickel Coated Simulated High Level Waste Glass Analyzed by Secondary Ion Mass Spectrometry

Secondary ion mass spectrometer (SIMS) analysis of insulator samples suffers from charge build up problems. Most widely used method for charge neutralization using SIMS is to coat the sample with a precious metal like Au, Pt or Pd and operating SIMS in negative secondary ion detection mode in conjunction with Normal incidence Electron Gun (NEG). For routine sample analysis, in order to investigate the surface, depth and spatial distribution of elements and molecules in the sample to study various phenomena (corrosion, diffusion, precipitate formation, grain boundary diffusion etc.), this method is less economical because of the use of precious metal in coating the sample. In the present work, a novel method for charge neutralization has been investigated by using Ni coating instead of Au, Pd or Pt on simulated HLW (High Level Liquid Waste) glass sample and carrying out SIMS analysis. Overlapping of normalized energy distribution curves for the elemental ions Ni- and Fe- in the Ni film (conductive) and HLW glass (non-conductive) respectively, confirmed that effective charge neutralization was obtained in the Ni coated sample. Surface, depth and 3D (3-Dimensional) distribution analyses of elements were also carried out after pre-sputtering the Ni film deposited on the sample which revealed uniform spatial distribution of all the elements in the HLW sample