AAAR 35th Annual Conference October 17 - October 21, 2016 Oregon Convention Center Portland, Oregon, USA
Abstract View
Light Pushing or Pulling of Absorbing Airborne Particles
CHUJI WANG, Zhiyong Gong, Yong-Le Pan, Gorden Videen, Mississippi State University
Abstract Number: 365 Working Group: Single Aerosol Particle Studies - Fundamentals
Abstract Optical manipulation of microscopic objects using light is an emerging tool used in diverse research fields such as physics, chemistry, biology, materials. Research related to optical manipulation using optical forces ranges from the early demonstration of particle levitation and trapping in different media such as solution or air to the recent breakthrough in controlled optical manipulation. Of those significant theoretical or experimental studies in controllable optical manipulation of small particles using light, the fundamental light-particle interaction phenomenon, light can push or pull a small particle, has been demonstrated using transparent spherical particles, transparent nonspherical particles, and absorbing spherical particles (all except absorbing nonspherical particles). Whether it is a general fundamental light-particle interaction phenomenon for arbitrary particles lies in a theoretical or experimental breakthrough in controlled optical manipulation for the last yet unexplored categoryabsorbing nonspherical particles. However, to the best of our knowledge, this challenge has been addressed neither theoretically nor experimentally.
Here we report our experimental observation that light can push or pull small absorbing non-spherical particles, too. A single absorbing particle formed by carbon nanotubes in the size range of 10-50 µm is trapped in air by a laser trapping beam and concurrently illuminated by another laser manipulating beam. When the trapping beam is terminated, the motion of the particle is controlled by the manipulating beam. Both pushing and pulling motions are observed. Additionally, the movement direction has little relationship to the particle size and manipulating beam’s parameters but is dominated by the particle’s orientation and morphology. With this observation, the controllable optical manipulation is now able to be generalized to arbitrary particles regardless of being transparent spherical, transparent non-spherical, absorbing spherical, or absorbing non-spherical that is shown in this work. Our observation would motivate future theoretical work to be extended for arbitrary particles. By then our understanding of optical forces would be unified.