拖曳效应对低相干动态光散射测量粒径的影响

Influence of Wall-Drag Effect on Particle Sizing in Low-Coherence Dynamic Light Scattering

低相干动态光散射技术利用低相干干涉计的特性,有效抑制了从浓悬浮液中散射的多次散射光,从而能够检测到的单散射光信号中获取颗粒的动态信息。该技术以单散射理论为解析基础,为避免多重散射的影响,测量区域一般局限于固-液界面附近。分析了固-液界面附近壁的拖曳效应对粒径测量值的影响。利用相位调制低相干动态光散射装置,对体积分数为10%的不同粒径的标准聚苯乙烯溶液进行了检测。通过对结果考虑拖曳效应进行修正,发现不同粒径的粒子在界面附近10～30μm范围内的测量值与给定粒径值标准偏差在5%以内。表明在低相干动态光散射光程可分割测量中,考虑拖曳效应的影响,可以对固-液界面附近的测量结果通过修正并得到准确的颗粒大小信息。

Low-coherence dynamic light scattering（DLS）technique can be used to obtain dynamic characteristics of particles from dense suspensions,in which the multiple scattered light can be effectively suppressed by use of low-coherence interferometer.Based on the single-scattering theory,the measurement region is usually limited to the vicinity of solid-liquid interface.Influences of wall-drag effect close to the interface on particle sizing in low-coherence DLS are investigated.Particle sizes are measured for polystyrene latex particles volume fraction of 10% with different radii using the phase modulated low-coherence dynamic light scattering measurement.The results are corrected by considering wall drag effects.It is found that the measured values of particle radii agree to the given values for different samples with the standard deviations within 5% in the region of 10~30 μm close to the interface.As a result,considering the wall-drag effect close to the interface,the accurate particle size information can be obtained near the interface region in the path-length resolved measurement of low-coherence DLS.