The importance of charge-transfer interactions in determining chromophoric dissolved organic matter (CDOM) optical and photochemical properties.
The importance of charge-transfer interactions in determining chromophoric dissolved organic matter (CDOM) optical and photochemical properties.
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DOI：
10.1039/c3em00573a
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发表时间：
2014-03
期刊：
影响因子：
--
通讯作者：
Charles M. Sharpless;N. Blough
中科院分区：
文献类型：
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作者：
Charles M. Sharpless;N. Blough
发色天然有机物(CDOM)对太阳光的吸收具有重要的环境意义，因为它控制着光区的深度，并引起影响元素循环和污染物归宿的光化学。CDOM的光学(吸光度和荧光)和光化学都显示出不寻常的性质，这些性质不容易归因于单个生色团的叠加。这些包括(I)广泛的、非结构化的吸收，它单调地下降到可见光和近红外，(Ii)荧光发射光谱，无论激发波长如何，都落在一个包层中，以及(Iii)光漂白和光化学量子产率随着波长的增加而单调下降。与简单的叠加模型相比，这些现象和其他现象可以用一个物理模型很好地解释，在这个物理模型中，CDOM中电子供体和接受发色团之间的电荷转移相互作用控制着光学和光物理性质。本文综述了目前人们对CDOM光物理和光化学过程及其物理基础的理解。
Absorption of sunlight by chromophoric dissolved natural organic matter (CDOM) is environmentally significant because it controls photic zone depth and causes photochemistry that affects elemental cycling and contaminant fate. Both the optics (absorbance and fluorescence) and photochemistry of CDOM display unusual properties that cannot easily be ascribed to a superposition of individual chromophores. These include (i) broad, unstructured absorbance that decreases monotonically well into the visible and near IR, (ii) fluorescence emission spectra that all fall into a single envelope regardless of the excitation wavelength, and (iii) photobleaching and photochemical quantum yields that decrease monotonically with increasing wavelength. In contrast to a simple superposition model, these phenomena and others can be reasonably well explained by a physical model in which charge-transfer interactions between electron donating and accepting chromophores within the CDOM control the optical and photophysical properties. This review summarizes current understanding of the processes underlying CDOM photophysics and photochemistry as well as their physical basis.