Computer simulation of the collision frequency of two particles in optical tweezers
Xu Sheng-Hua (徐升华)ab, Li Yin-Mei (李银妹)ab, Lou Li-Ren (楼立人)a, Sun Zhi-Wei (孙祉伟)a
a Department of Physics, University of Science and Technology of China, Hefei 230026, China; b National Laboratory for Physical Science at Microscale, University of Science and Technology of China, Hefei 230026, China
Abstract Optical tweezers have been successfully used in the study of colloid science. In most applications people are concerned with the behaviour of a single particle held in the optical tweezers. Recently, the ability of the optical tweezers to simultaneously hold two particles has been used to determine the stability ratio of colloidal dispersion. This new development stimulates the efforts to explore the characteristics of a two-particle system in the optical tweezers. An infinite spherical potential well has been used to estimate the collision frequency for two particles in the optical trap based on a Monte Carlo simulation. In this article, a more reasonable harmonic potential, commonly accepted for the optical tweezers, is adopted in a Monte Carlo simulation of the collision frequency. The effect of hydrodynamic interaction of particles in the trap is also considered. The simulation results based on this improved model show quantitatively that the collision frequency drops down sharply at first and then decreases slowly as the distance between the two particles increases. The simulation also shows how the collision frequency is related to the stiffness of the optical tweezers.
Received: 04 April 2004
Revised: 06 September 2004
Accepted manuscript online:
(Mechanical effects of light on atoms, molecules, and ions)
Fund: Project supported by the National Natural Science Foundation of China (Grant No 20273065) and "the Knowledge Innovation Programme" of Chinese Academy of Sciences.
Cite this article:
Xu Sheng-Hua (徐升华), Li Yin-Mei (李银妹), Lou Li-Ren (楼立人), Sun Zhi-Wei (孙祉伟) Computer simulation of the collision frequency of two particles in optical tweezers 2005 Chinese Physics 14 382
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