Light-torqued nanomotors free of a surface

摘要

We use polarized light to generate light torques for controlling nanoparticles and for producing nanomotors. We report on experiments where we apply light torques to glass nanorods in an optical trap at a known distance from a nearby surface. We tried two different optical traps: (1) a standing wave trap using 20 mW and (2) a single beam trap using 80 mW of light at wavelength 514 nm from an Ar+ laser. The rods studied here are 250-500 nm in diameter and are 1-4 microns long. The motion of the rotating rods is studied and a theoretical model of the motion is presented. The motion can be heavily affected by the presence of a nearby surface. For example, past studies have provided evidence that rotatory motion near a surface can change to rocking motion and vice versa. In this study, we present results of motion free of such surface effects. Studies of the motion of nano-objects are useful in understanding nanorheological phenomena in both biological and inorganic systems.