van Holde - Weischet Tutorial

Speed too large/experiment too long

Figure 17: Single component system. Scans drawn in red do not have a stable plateau and should not be included in the analysis. If the same number of scans is desired, the speed should be reduced (or the scan delay should be reduced, if possible).

Figure 18: van Holde - Weischet analysis of data including scans drawn in red. The extrapolation plot clearly shows a diagnostic identifying the scans that should be excluded from the analysis. All scans which do not have a stable plateau display the loss of material in the upper boundary fractions and cause poor correlation in the linear fits. The extrapolation lines cross over similar to concentration dependent samples, however, after excluding inappropriate scans, the data reverts to nearly perfect correlation (see below).

Figure 19:van Holde - Weischet analysis of data excluding scans drawn in red. The extrapolation plot shows a good correlation for all scans across the entire boundary.