Acid-Base Clusters during Atmospheric New Particle Formation in Urban Beijing
Acid-Base Clusters during Atmospheric New Particle Formation in Urban Beijing
复制标题
北京城区大气新颗粒物形成过程中的酸碱团簇
DOI：
10.1021/acs.est.1c02701
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发表时间：
2021
影响因子：
11.4
通讯作者：
Jiang Jingkun
中科院分区：
文献类型：
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作者：
Yin Rujing;Yan Chao;Cai Runlong;Li Xiaoxiao;Shen Jiewen;Lu Yiqun;Schobesberger Siegfried;Fu Yueyun;Deng Chenjuan;Wang Lin;Liu Yongchun;Zheng Jun;Xie Hongbin;Bianchi Federico;Worsnop Douglas R.;Kulmala Markku;Jiang Jingkun
分子成团是大气新粒子形成的第一步，产生大量的二次粒子。利用两台带和不带化学电离入口的在线质谱仪，对北京城区NPF期间的中性团簇和自然带电离子团簇进行了表征。在离子团簇中，我们观察到了纯硫酸（SA）团簇、SA-胺团簇、SA-氨（NH 3）团簇和SA-胺-NH 3团簇。然而，只有SA簇和SA-胺簇中观察到的中性形式。同时，在离子簇中观察到由硝酸根离子和硫酸氢根离子充电的含氧有机分子（OOM）簇。酸碱团簇与3 nm以下颗粒的出现有很好的相关性，而OOM团簇则没有。随着团簇尺寸的增大，离子型酸碱团簇中的胺组分减少，而NH3组分增加.这种变化是由于SA-胺簇合物和SA-NH 3簇合物之间稳定性差异减小所致，这一点得到了量子化学计算和小室实验的支持。二甲胺（DMA）分子在大气离子团簇中的平均数低于SA-DMA成核实验的饱和值，表明北京城区DMA不足以完全稳定大的SA团簇，因此NH3等其他基本分子起着重要作用。
Molecular clustering is the initial step of atmospheric new particle formation (NPF) that generates numerous secondary particles. Using two online mass spectrometers with and without a chemical ionization inlet, we characterized the neutral clusters and the naturally charged ion clusters during NPF periods in urban Beijing. In ion clusters, we observed pure sulfuric acid (SA) clusters, SA–amine clusters, SA–ammonia (NH3) clusters, and SA–amine–NH3clusters. However, only SA clusters and SA–amine clusters were observed in the neutral form. Meanwhile, oxygenated organic molecule (OOM) clusters charged by a nitrate ion and a bisulfate ion were observed in ion clusters. Acid–base clusters correlate well with the occurrence of sub-3 nm particles, whereas OOM clusters do not. Moreover, with the increasing cluster size, amine fractions in ion acid–base clusters decrease, while NH3fractions increase. This variation results from the reduced stability differences between SA–amine clusters and SA–NH3clusters, which is supported by both quantum chemistry calculations and chamber experiments. The lower average number of dimethylamine (DMA) molecules in atmospheric ion clusters than the saturated value from controlled SA–DMA nucleation experiments suggests that there is insufficient DMA in urban Beijing to fully stabilize large SA clusters, and therefore, other basic molecules such as NH3play an important role.