Abstract: The romance of a bottle of wine and a technicolor sunset – perhaps the perfect pairing of a liquid-liquid mixture with light scattering phenomena. This talk will strive for a second-best pairing by showing how light scattering may be used to understand the physical properties of liquid-liquid mixtures. At first glance, pouring two nonreactive liquids together to make a mixture seems like a very simple physical process. Sometimes two liquids mix completely, like ethanol and water do in alcoholic beverages. Sometimes the liquids stay in two layers and do not mix very much at all, like oil and water. However, many pairs of liquids show both types of behavior: the liquids mix completely for some temperatures and some mixing ratios, but the liquids separate into two layers at other conditions. In this talk I will discuss the laser light scattering method we use to make maps of the exact conditions in which two liquids mix to form a single layer, or phase. I will introduce special points on the maps called critical points, and show the universal and beautiful physical behavior that all liquid-liquid mixtures exhibit at a critical point, like critical opalescence and spinodal decomposition. I will also present a new type of fundamental liquid-liquid phase behavior my students and I have observed here at Willamette. Throughout the talk I will illustrate the complex ways in which light can scatter from a liquid-liquid mixture by incorporating examples of light scattering found in the atmosphere, such as the whiteness of clouds and fog, the blueness of the sky, and solar halos. There is also a brief shout out to Edvard Munch.
Please feel free to invite students to attend this talk.
We look forward to seeing you there.
Doreen Simonsen and Bobby Brewer-Wallin
Faculty Colloquium Coordinators