Interestingly, some compositions of the DMDBPMA/hexane mixture have larger values of I Q=0 (but not ξ) than longer alkanes. This can be attributed to the larger density difference between shorter alkane diluents and the extractant than for longer alkanes (DMDBPMA has a mass density of 0.935 g/cm 3 compared to 0.750 g/cm 3 for dodecane and 0.655 g/cm hexane ), which contributes to I Q=0 but not ξ. Decreasing diluent chain length reduces the correlation length of fluctuations less and less at smaller chain lengths, but the decrease in diluent density remains roughly linear with chain length. Therefore, the contribution to I Q=0 from the increasing difference in density between the two components out-competes the decrease in concentration fluctuations at sufficiently low diluent chain length. We account for this by converting I Q=0 to a structure factor using