Isoprene is a crucial precursor of secondary organic aerosols (SOAs) that reacts with radicals or oxidants such as OH, O3, and NO3. The reaction mechanisms under various conditions have been elucidated through years of research. In this study, the UV–vis light absorptive ability of oxydates for isoprene was calculated at the PBE1PBE/6-311g (d) level using Gaussian 09. The results indicated that reactions of isoprene with OH and O3 would produce less absorptive organics; the intensity of the absorption peaks and the maximum absorption wavelength decreased relative to those of the precursor. The oxydates formed from isoprene through an NO3-initiated reaction had different light absorption properties. The optical properties of the oxydates exhibited a bathochromic shift and hyperchromic effect relative to those of the precursor. NO3 mainly originated from vehicular traffic, indicating that anthropogenic activity heavily affected the formation of oxydates and light absorption. The light absorption properties and irradiation effect of SOAs caused by isoprene heavily depended on the reaction route. Transformation of functional groups was the dominated factor in photobleaching and photoenhancement of oxidative products. This study provides a detailed mechanism that explains the changes in optical absorption properties during isoprene oxidation.

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从前体（异戊二烯）到其大气氧化产物的光学特性变化

异戊二烯是二次有机气溶胶 (SOA) 的重要前体，可与自由基或氧化剂（如 OH、O3 和 NO3）发生反应。经过多年的研究，已经阐明了各种条件下的反应机理。在本研究中，使用 Gaussian 09 在 PBE1PBE/6-311g (d) 水平计算了氧化物对异戊二烯的紫外-可见光吸收能力。吸收峰的强度和最大吸收波长相对于前驱体的强度降低。异戊二烯通过 NO3 引发的反应形成的氧化物具有不同的光吸收特性。相对于前体的光学性质，氧化物的光学性质表现出红移和增色效应。NO3 主要来源于车辆交通，表明人为活动严重影响了氧化物的形成和光吸收。异戊二烯引起的 SOA 的光吸收特性和辐照效果在很大程度上取决于反应路线。官能团的转化是氧化产物光漂白和光增强的主要因素。这项研究提供了解释异戊二烯氧化过程中光吸收特性变化的详细机制。官能团的转化是氧化产物光漂白和光增强的主要因素。这项研究提供了解释异戊二烯氧化过程中光吸收特性变化的详细机制。官能团的转化是氧化产物光漂白和光增强的主要因素。这项研究提供了解释异戊二烯氧化过程中光吸收特性变化的详细机制。