The influence of ions on atmospheric particle growth - flow tube and aerosol chamber studies

二次气溶胶的形成是大气中颗粒物的主要来源，对气候和人类健康具有重要影响。本计画探讨在实验室控制条件下，于流管及气溶胶室实验中，空气离子在二次气溶胶形成中所扮演的角色。尽管在测量大气成核和颗粒增长能力方面取得了相当大的进展，但在理解基本的物理和化学过程方面仍然存在差距。特别是，离子-粒子相互作用和离子化学对二次气溶胶形成的潜在影响是科学讨论的主题。作为现有研究工作的补充，调查离子在初始成核步骤中的作用，我们建议研究离子-粒子相互作用，在随后的颗粒生长的重点是直接测量的充电状态，增长率和化学成分的二次有机气溶胶。要做到这一点，充电状态和增长率的气溶胶人口将在定义明确的条件下，在实验室实验中与修改后的迁移率粒子光谱仪进行量化。下一步，我们将充分利用气溶胶质谱仪CAChUP的新测量能力，量化不同充电状态下不同有机前体气体对二次有机气溶胶化学成分的贡献。最后，这些实验的结果将与气溶胶室设置研究二次有机气溶胶形成在定义明确的离子浓度进行验证。因此，拟议的研究议程的目的是解开离子化学二次气溶胶形成的潜在贡献。

Secondary aerosol formation is a major source of particles in the atmosphere with important implications for climate and human health. This project investigates the role of air ions in secondary aerosol formation both in flow tube and aerosol chamber experiments under controlled laboratory conditions. Despite considerable progress with respect to measuring capabilities for atmospheric nucleation and particle growth, gaps still exist in the understanding of the underlying physical and chemical processes. In particular, the potential impact of ion-particle interactions and ion chemistry on secondary aerosol formation is a topic of scientific discussion. As a complement to existing research efforts, which investigate the role of ions in the initial nucleation step, we propose to study ion-particle interactions in subsequent particle growth with a focus on direct measurements of the charging state, the growth rates and the chemical composition of secondary organic aerosol. To do this, the charging state and growth rates of aerosol populations will be quantified under well-defined conditions in laboratory experiments with a modified mobility particle spectrometer. In a next step, we will fully exploit the novel measuring capabilities of our aerosol mass spectrometer CAChUP, quantifying the contribution of different organic precursor gases at various charging states to the chemical composition of the secondary organic aerosol. Finally, the findings of these experiments will be validated with an aerosol chamber setup studying secondary organic aerosol formation at well-defined ion concentrations. Thus, the proposed research agenda is designed to untangle the potential contributions of ion chemistry to secondary aerosol formation.