de Boer F Y, van Dijk-Moes R J A, Imhof A, Velikov K P
Soft Condensed Matter & Biophysics, Debye Institute for Nanomaterials Science , Utrecht University , Princetonplein 1 , 3584 CC Utrecht , The Netherlands.
Unilever R&D Vlaardingen , Olivier van Noortlaan 120 , 3133 AT Vlaardingen , The Netherlands.
Langmuir. 2019 Sep 17;35(37):12091-12099. doi: 10.1021/acs.langmuir.9b01357. Epub 2019 Sep 9.
In this research, we model the color of optically dense colloidal dispersions of dyed and undyed zein particles using results from multiple light scattering theory. These particles, as well as monodisperse silica colloids, were synthesized and characterized to obtain particle properties such as particle size, particle size distribution, refractive index, and absorption spectrum of the dye. This information was used to model the diffuse transmission of concentrated particle dispersions, which was measured using a specially designed variable path length quartz glass cuvette. For the nonabsorbing silica dispersions, a transport mean-free path throughout the visible range was obtained. Results showed a difference of less than 5% from the values calculated with a multiple scattering model using the single-particle properties as an input. For undyed zein particles, which are off-white, the deviation between the model and the experiment was about 30% because of slight absorption at wavelengths below 550 nm but <7% at higher wavelengths. From these results, it was concluded that the model correctly describes diffuse transmission and that the measurements are sensitive to absorption. Finally, this method was applied to dispersions of dyed zein particles. Here, the transport mean-free path was first determined for wavelengths at which there is no absorption, which agreed with the theory better than 4%. The modeled transport mean-free path was then used to extract the reciprocal absorption mean-free path in the remaining parts of the visible spectrum, and a reasonable agreement with the absorption spectrum of the dye solution was obtained.
在本研究中，我们利用多重光散射理论的结果对染色和未染色的玉米醇溶蛋白颗粒的光学致密胶体分散体的颜色进行建模。合成并表征了这些颗粒以及单分散二氧化硅胶体，以获得颗粒性质，如粒径、粒径分布、折射率和染料的吸收光谱。这些信息用于对浓颗粒分散体的漫透射进行建模，漫透射是使用专门设计的可变光程石英玻璃比色皿测量的。对于非吸收性二氧化硅分散体，获得了整个可见光范围内的输运平均自由程。结果表明，与使用单颗粒性质作为输入的多重散射模型计算的值相差不到5%。对于灰白色的未染色玉米醇溶蛋白颗粒，由于在波长低于550 nm时存在轻微吸收，模型与实验之间的偏差约为30%，但在较高波长时偏差小于7%。从这些结果可以得出结论，该模型正确地描述了漫透射，并且测量对吸收敏感。最后，将该方法应用于染色玉米醇溶蛋白颗粒的分散体。在这里，首先确定了无吸收波长下的输运平均自由程，其与理论的吻合度优于4%。然后，使用建模的输运平均自由程来提取可见光谱其余部分的倒数吸收平均自由程，并与染料溶液的吸收光谱获得了合理的吻合。
