多角度动态光散射法的纳米颗粒精确测量

基于动态光散射原理,采用自主研发的多角度动态光散射装置,对纳米及亚微米颗粒粒径准确测量方法进行了探究。自研装置采用带有光阑组的精密入射光路设计,以及匹配液池及Beam-stop设计,极大提高了信噪比;同时避免了测量角度的互补方向上,由于样品池与空气界面折射率不同导致的反射光信号对有效信号的干扰。在此基础上,对不同浓度、粒径的聚苯乙烯(PS)颗粒溶液进行了测定及不确定度分析。结果表明,对同一粒径的PS颗粒,增加颗粒浓度时,多重散射首先发生于大、小测量角度,越接近90°,发生多重散射的浓度越高;随着粒径增大,受不可忽略的颗粒间相互作用的影响,粒径测量结果表现出了强烈的角度依赖性,甚至波动性。

Accurate Measurement of Nanoparticles By Using Multi-angle Dynamic Light Scattering

Based on the principle of dynamic light scattering, an independent multi-angle dynamic light scattering device was used to investigate the accurate measurement methods of nano and submicron particle size. The precision incident light path design with diaphragm group, matching liquid pool and beam-stop design were adopted in the self-developed device, which greatly improved the signal-to-noise ratio. At the same time, the interference of the reflected light signal caused by the different refractive index between the sample cell and the air interface in the complementary direction of the measurement angle was avoided. On this basis, the polystyrene (PS) particle solution with different concentration and particle size was determined and its uncertainty was analyzed. The results showed that for PS particles with the same particle size, multiple scattering first occurs at large and small measurement angles when the particle concentration is increased. The closer to 90°, the higher the multiple scattering concentration is. With the increase of particle size, the particle size measurement results showed a strong angular dependence and even volatility due to the non-negligible interaction between particles.