Real-time three-dimensional single-particle tracking spectroscopy for complex systems

Complex systems are characterized by dynamical processes spread over multiple time and length scales. At a given instant, these systems can display spatial heterogeneities in which the local physical and chemical properties are non-uniform, depending on the location. They can also exhibit dynamical heterogeneities in which the local dynamical characteristics vary with time. These types of systems pose unique experimental challenges for their characterization and test of theoretical ideas. Recently, real-time three-dimensional (3D) single-particle tracking spectroscopy has been developed to address these kinds of problems. With this approach, in principle, one can follow how a system evolves spatially as well as temporally. This article attempts to provide an introduction to this promising new technique by discussing the aims of studying a complex system Cartoon illustrating a complex system, whose dynamics change and recent experimental advances towards this goal. as a function of time and position, studied using 3D particle-tracking spectroscopy.