SAMPLE PREPARATION: The importance of being flat
Sample topography (polishing relief) has a significant effect on the precision and accuracy of WiscSIMS analyses.
Details of the effects of sample topography are reported in Kita et al. (2009). Kita et al. nicely illustrates the effect of polishing relief on the reproducibility of oxygen isotope measurements in zircon standard grains (KIM5). Here is a visual summary of their results (pdf). A polishing relief of <3 μm is generally necessary for high-precision analysis, and a relief of <1 μm is optimal. For epoxy mounts made for other analyses (e.g. U-Pb analysis by SIMS), polishing relief is sometimes ~10 μm. You can remove this type of relief by hand with 3 μm and 1 μm diamond lapping films in succession.
For the sake of the quality of your results, please take the utmost care to obtain a flat analytical surface with as few scratches as possible.
The next sections will offer advice on how best to prepare flat samples.