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Measurement and Evaluation of Elastic Light Scattering from a Single Levitated Irregular Particle
Yuan-Yi Kao1, Sheng-Hsiu Huang2, Chih-Chieh Chen2, Cheng-Shiun Tsai1, Chang-Huei Wu3, Wen-Yinn Lin1
1 Institute of Environmental Engineering and Management, National Taipei University of Technology, Taipei 10608, Taiwan
2 Institute of Occupational Medicine and Industrial Hygiene, National Taiwan University, Taipei 10617, Taiwan
3 Department of Mechanical Engineering, Yuan Ze University, Taoyuan 320, Taiwan
- The EDB was used to levitate a single irregular particle.
- The Lorenz-Mie theory was employed to compute the Mie intensity.
- A Raman spectroscopy was utilized to the elastic light scattering.
- The elastic scattering of a PMMA and carbon particle were measured and evaluated.
This study introduced a convenient experimental method to measure and to evaluate the elastic light scattering from a single irregular particle. The particle levitation system was used to trap a particle and to maintain the particle at null position by utilizing electrodynamic balance. Moreover, the Raman spectroscopy was applied to observe the light scattering of a single particle. The influences of relative humidity on optical properties of particle were also discussed. For comparison with experimental results, the classical Lorenz-Mie theory was employed to compute the phase function of a single particle. The experimental results demonstrated that the measurements of light scattering were in approximate trend with the model. In particular, numerical simulation results showed that the scattering intensity was underestimated in backward scattering directions. Consequently, the effect of surface roughness and irregular morphology of particle might be resulted in deviations of backward scattering. Besides, the experiments suggested that while using the weighted average method to estimate the refractive index might cause some significant deviations of light scattering between measuring and modeling.
Irregular particle; Light scattering; Electrodynamic balance; Levitation.