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杂质有助于和脂肪酸的紫外线吸收

Shota Saito¹, Naoki Numadate¹, Hidemasa Teraoka¹

¹Komaba Institute for Science and Department of Basic Science, The University of Tokyo, Meguro, Tokyo 153-8902, Japan.

Science advances

|September 20, 2023

概括

认为海洋中和脂肪酸的光化学反应会产生挥发性有机化合物. 这项研究揭示了以前在非纳米酸中观察到的长波长光吸收是由于杂质而不是酸本身.

科学领域:

大气化学大气化学
有机地化学有机地化学

背景情况:

和脂肪酸在海洋环境和海洋喷雾中丰富.
它们的光化学反应是已知的挥发性有机化合物 (VOC) 的非生物来源.
挥发性有机物作为二次有机气溶 (SOA) 的前体.
自1931年以来,液体和脂肪酸的长波长光吸收 (>250 nm) 已经无法解释.

研究的目的:

调查液体和脂肪酸,特别是非酸中长波长光吸收无法解释的来源.
为了确定非酸本身与杂质在这种光吸收中的作用.

主要方法:

液体非酸的光谱分析.
在非纳米酸试剂中的杂质含量量定量.
净化非酸的吸收截面的确定.

主要成果:

之前报道的非纳米酸在波长>250nm的光吸收归因于微量杂质 (≤0.1%).
新获得的吸收截面显示,在这个范围内,nonanoic酸的光吸收率非常低.
非纳米酸的光解速率明显低于大气相关的碳烯化合物 (3-5个数量级).

结论:

杂质,而不是nonanoic酸的内在性质,解释了其报告的长波长光吸收.
像非酸这样的和脂肪酸不太可能在太阳辐射下成为大气VOCs的显著直接光解前体.
这一发现澄清了大气和海洋有机化学中长期存在的问题.

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