The surface stoichiometry of five samples, two semiconductors (GaAs and InP) and three minerals (galena (PbS), pyrite (FeS2) and sphalerite (Zn, Fe) S), has been determined by a range of surface analysis techniques: ToF-SIMS, XPS, RBS, NRA and PIXE. The strengths and limitations of the five surface and interface analytical techniques have also been assessed by challenging each technique with the above mentioned samples. As a result, a strategy tree for the quantitative surface analysis of real mixed mineral systems has been developed for novice investigators as an operational guide. ToF-SIMS is a technique able to detect species from hydrogen to very complex organic modules with very high sensitivity. SIMS is generally not a quantitative technique due primarily to the matrix effect, i.e. the strong dependence of secondary ion yields on the chemical composition of the sample. However, for well defined systema, quantitative analyses are possible if suitable calibration standards are accessible. / In this study, a preliminary RSF (Relative Sensitivity Factor) study has been conducted on five samples to give RSFs of the major constituents of each sample. XPS is broadly recognised as a surface analysis technique with the ability of determining the elemental composition near the surface region as well as chemical information, but the depth resolution of XPS is poor. RBS is capable of revealing the concentration depth profiles within the sample without destroying the solid surface. RBS is also considered a good quantitative analytical technique. The main disadvantages of RBS are the poor surface sensitivity and the low efficiency in detecting light elements in a high Z substrate. PIXE is a non-destructive multi-element analytical technique based on X-ray spectroscopy and good at detecting medium Z elements (Z~/= 20~30). By using L X-ray lines instead of K X-ray lines, PIXE is also able to detect high Z (>40) elements. However, due to the very low detection efficiency of Si (Li) detectors (typical PIXE detectors) at low X-ray energies, elements lighter than sodium can not be analysed. Another major shortcoming of PIXE is the lack of depth information. Various surface textures of pyrite have been studied in order to investigate the influence of surface conditions on the quantitative results for the individual techniques utilised in this study and the activation induced chemical alteration on pyrite surfaces has also been studied in detail. By comparing the results from these surface analysis techniques, a good understanding of the elemental composition of the mixed minerals has been achieved. / Thesis (PhD)--University of South Australia, 2004.
| Identifer | oai:union.ndltd.org:ADTP/267635 |
| Creators | Gong, Zhenfang |
| Source Sets | Australiasian Digital Theses Program |
| Language | English |
| Detected Language | English |
| Rights | copyright under review |
Page generated in 0.0017 seconds