Effects of weak attractions. Adding interparticle attractions without modifying the volume fraction provides another window into the role of interparticle structural correlations on the optical response of disordered nanomaterials. Interparicle attraction strengths between 0k B T < U 0 ≤ 3k B T are weak enough so that particles remain mobile in a dispersed fluid phase, but strong enough to enhance the structural correlations relative to hard spheres.