Development of a nanosecond time-resolved Brewster angle microscope to observe phase change at an interface

A nanosecond time-resolved Brewster angle microscope was developed in order to observe pulsed-laser-induced spinodal de-mixing of binary liquid mixtures of triethylamine (TEA)–water and 2-butoxyethanol (2BE)–water at interfaces. At an air–liquid interface the phase changing regions spread across the liquid surface due to convection, which also resulted in the formation of larger domain areas than were observed at a quartz–liquid interface, for which convectional spreading was not observed. In the case of 2BE–water, de-mixing at an air–liquid interface, the domains developed a branched structure in the late stages of coarsening. At the same time the Reynolds numbers of the growing phases were estimated to be >3, which may account for the morphological changes that were observed in this time.