Effects of Cascading Optical Processes: Part II: Impacts on Experimental Quantification of Sample Absorption and Scattering Properties
Effects of Cascading Optical Processes: Part II: Impacts on Experimental Quantification of Sample Absorption and Scattering Properties
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DOI：
10.1021/acs.analchem.2c05055
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发表时间：
2023-02-14
影响因子：
7.4
通讯作者：
Zhang，Dongmao
中科院分区：
文献类型：
--
作者：
Wathudura，Pathum;Wamsley，Max;Zhang，Dongmao
在三篇配套文章的第一部分中，我们报道了光散射对实验定量散射消光，强度和去极化的影响，这些溶液只含有散射体，没有显着的吸收和光致发光活动。目前的工作（第二部分）研究了光散射和吸收的影响，对一系列的光谱测量样品，包含吸收体和散射体，但没有发射器。实验紫外-可见光谱是样品吸收和散射消光光谱的总和。然而，前向散射光的干涉会过早地限制实验中遵守比尔定律的消光的上限。光的吸收不仅降低了样品的散射强度，而且降低了散射的退偏。散射对样品光吸收的影响是复杂的，这取决于是否考虑散射光的吸收。散射减少了沿着从激发源到UV-vis检测器的光路长度的光吸收。然而，散射光的吸收可以足以补偿沿这种光路沿着减少的光吸收，使得光散射对样品总光吸收的影响小得可以忽略（<10%）。后者的发现构成了一个关键的验证积分球辅助共振同步光谱方法的实验量化的吸收和散射的贡献样品的紫外-可见消光光谱。在这项工作中提供的技术和一般准则应有助于提高纳米级或更大的材料，其中许多是同时吸收和散射的光学光谱表征的可靠性。这项工作的见解是本系列工作的第三部分的基础，这是关于荧光样品光谱测量的级联光学过程。
In Part I of the three companion articles, we reported the effects of light scattering on experimental quantification of scattering extinction, intensity, and depolarization in solutions that contain only scatterers with no significant absorption and photoluminescence activities. The present work (Part II) studies the effects of light scattering and absorption on a series of optical spectroscopic measurements done on samples that contain both absorbers and scatterers, but not emitters. The experimental UV–vis spectrum is the sum of the sample absorption and scattering extinction spectra. However, the upper limit of the experimental Beer’s-law-abiding extinction can be limited prematurely by the interference of forward scattered light. Light absorption reduces not only the sample scattering intensity but also the scattering depolarization. The impact of scattering on sample light absorption is complicated, depending on whether the absorption of scattered light is taken into consideration. Scattering reduces light absorption along the optical path length from the excitation source to the UV–vis detector. However, the absorption of the scattered light can be adequate to compensate the reduced light absorption along such optical path, making the impacts of light scattering on the sample total light absorption negligibly small (<10%). The latter finding constitutes a critical validation of the integrating-sphere-assisted resonance synchronous spectroscopic method for experimental quantification of absorption and scattering contribution to the sample UV–vis extinction spectra. The techniques and general guidelines provided in this work should help improve the reliability of optical spectroscopic characterization of nanoscale or larger materials, many of which are simultaneous absorbers and scatterers. The insights from this work are foundational for Part III of this series of work, which is on the cascading optical processes on spectroscopic measurements of fluorescent samples.