AAAR 34th Annual Conference
October 12 - October 16, 2015
Hyatt Regency
Minneapolis, Minnesota, USA
Abstract View
Optical Trap, Manipulation, and Characterization of Light-absorbing Single Aerosol Particles in Air
CHUJI WANG, Yong-Le Pan, Zhiyong Gong, Brandon Redding, Mississippi State University, US Army Research Laboratory
Abstract Number: 481 Working Group: Aerosol Physics
Abstract We report on light-absorbing particle trap and transport in air using a simply focused Gaussian beam. Trapping a single particle at a point, several particles in a line, and many particles on a plan is demonstrated at 488 nm. Furthermore, transporting a single stably trapped particle in three dimensions in air is achieved. In addition to the normally observed pulling force on light-absorbing particles, we show strong pushing force that shoots particles along the propagation direction of the laser beam. This phenomenon is wavelength independent at the wavelengths of 266 nm, 409 nm, and 532 nm used in this work.
These latest experimental observations pose a big challenge in explanation of the forces, torques, and motions of the light-absorbing particles, e.g. Bermuda grass spores, small wall carbon nanotubes, multi-wall carbon nanotubes, and carbon blacks. An extensive literature survey shows that there is no single theory that can be universally applicable to explanation of the observed phenomena of the light absorbing particles under light illumination. Tentative speculation and discussion with regard to trapping forces and motions of the particles are presented.
Finally, some preliminary results of Raman and cavity ringdown spectroscopy of single particles trapped in air are also reported.
This research was supported by the US Army Research Office grants (W911NF-13-1-0429 and W911NF-13-1-0297), the Defense Threat Reduction Agency (DTRA), and the ARL mission funds.