Optical and Nanoscopic Physics

Professor Bonin's research interests include studying fundamental optical properties of nanoparticles and in using nanoparticles to study important physical systems - specifically nanomotors and biomolecular motors. Light forces and light torques have been applied in unique ways to nanoscopic systems. We have successfully produced a light-driven nanomotor that uses optical tweezers to trap glass nanorods. Close to a surface, surface effects play a large role in the motion of such motors. When moved away from a surface, the motion is nonlinear with interesting behavior once the nanomotor is driven above a critical frequency determined by the particle polarizability, the light intensity, and the viscosity of the surrounding medium. Such a system could potentially probe the effects of chaotic motion in a regime where viscosity is made negligible.

Current experiments involve attempts to control and manipulate smaller nanoparticles. – This are developing techniques to optically manipulate single nanoparticles to produce novel nanoelectronics or chemical sensors. These investigations involve cw lasers and a research-class microscope in conjunction with interesting nanostructures. Our optical tweezers nanomotor setup currently consists of an AR+ ion laser coupled into an Olympus microscope.

Another area of interest is the use of light and novel techniques, such as single-molecule detection, optical tweezers, and total-internal reflection to investigate and understand the operation of biological motors. In collaboration with biophysicists in the department and neurobiolgists at the Wake Forest University School of Medicine, the detailed motion of molecular motors in vivo is being studied. This research involves the use of a research-class microscope and a advanced imaging and tracking system.