Understanding how gases interact with and are incorporated into atmospheric secondary organic aerosol particles is crucial for predicting particle effects on climate and human health. This work examined how three gaseous organic nitrates (ON) are taken up into viscous particles formed from the ozonolysis of α-pinene (AP). Experiments were performed in a flow reactor at room temperature under dry conditions, either with or without an OH scavenger present, with constant ozone and variable AP concentrations. Each ON was introduced independently into the flow reactor and was present during particle formation/growth. ON gas-phase concentrations were determined by gas chromatography–mass spectrometry, and particle phase concentrations were measured by high-resolution time-of-flight aerosol mass spectrometry. Partition coefficients (K_SOA) for each ON were independent of the initial AP concentration, except for 2-ethylhexyl nitrate which was undetectable in the particles at the lowest AP concentration. Measured K_SOA values were larger than those previously determined for equilibrium partitioning, which points to a potential burying mechanism for incorporation of ON during particle growth. Estimated effective net uptake coefficients (γ_ΟΝ) were found to increase with initial AP concentration. Concentrations of gas-phase oxidation products (including dimers and autoxidation products) predicted using an updated master chemical mechanism increased with AP concentration, with little change in the overall species distribution, consistent with increased trapping/burying of ON during particle growth and thus increased values of γ_ΟΝ. These results provide further evidence that kinetically controlled burying can contribute significantly to particle growth, provided that the incoming gas-phase molecules have sufficient residence time on the particle surface to become buried via subsequent gas–surface collisions.

中文翻译：

---

α-P烯臭氧分解过程中气体吸收的增加表明了埋藏机制

了解气体如何与大气中的次级有机气溶胶颗粒相互作用并掺入其中，对于预测颗粒对气候和人类健康的影响至关重要。这项工作研究了如何将三种气态有机硝酸盐（ON）吸收到由α-pine烯（AP）的臭氧分解作用形成的粘性颗粒中。实验是在室温下在干燥条件下的流动反应器中进行的，有或没有OH清除剂，且臭氧恒定且AP浓度可变。每个ON独立地引入到流动反应器中，并在颗粒形成/生长期间存在。通过气相色谱-质谱法确定ON气相浓度，并通过高分辨率飞行时间气溶胶质谱法测量颗粒相浓度。分配系数（每个ON的K _SOA）均与初始AP浓度无关，除了在最低AP浓度下无法在颗粒中检测到的硝酸2-乙基己基硝酸酯外。测得的K _SOA值大于先前为平衡分配确定的K _SOA值，这表明在颗粒生长过程中掺入ON的潜在掩埋机制。估计有效净摄取系数（_γΟΝ被发现随着初始AP浓度的增加而增加。使用更新的主化学机制预测的气相氧化产物（包括二聚体和自氧化产物）的浓度随AP浓度的增加而增加，总体物种分布变化不大，与颗粒生长过程中ON的捕获/掩埋增加有关，因此值增加的γ _ΟΝ。这些结果提供了进一步的证据，即只要进入的气相分子在颗粒表面上具有足够的停留时间以通过随后的气-面碰撞而被掩埋，动力学控制的掩埋就可以显着促进颗粒的生长。