That is, more extractant is needed to maximize fluctuations the stronger those fluctuations are. This is attributed to the negative slope of the Widom line in the φ E -T phase diagram that is imparted by the asymmetry in the high-and low-density branches of the liquid-liquid coexistence curve. This impacts the slope of the line of rectilinear diameters, which the Widom line tracks into the single phase region.