Before interpreting the ddGs in more detail, we would like to establish that the signals are, indeed, the PDF of amine-water MCSs in the amine-water mixture and not artifacts of data acquisition and pro-cessing. We note that the measured ddG, (Figure , red and yellow) and that computed from MD simulations (described below, Figure , blue), are very similar. The similarity gives confidence that, on the one hand, the measured signal is originating from the sample and, on the other, that the MD is correctly capturing atomic arrangements in the mixture. We also address a possible concern that the subtraction according to Eq. 2 (Experimental section) did not correctly subtract one of the components. This can be ruled out on the basis that the major features in the ddG do not line up with strong peaks in the total PDFs, G, of pure water (gray) or pure DIPA (green) in Figure . Thus, features in the ddG are only present in the mixture and cannot be attributed to imperfectly subtracted total PDF components. Finally, confidence comes from the fact that the ddG is highly reproducible. Measurements taken of different samples with similar compositions, measured months apart at different x-ray beamlines (NSLS-II, 28-ID-1 and 28-ID-2), and in slightly different experimental geometries, yield remarkably similar ddG curves (Figure , red and yellow). We can be confident that the signal is intrinsic to the samples.