Institute of Meteorology and Climate Research, Karlsruhe Institute of Technology, Karlsruhe 76344, Germany.
Institute of Geography and Geoecology, Working Group for Environmental Mineralogy and Environmental System Analysis, Karlsruhe Institute of Technology, Karlsruhe 76131, Germany.
Environ Sci Technol. 2023 Jun 20;57(24):8965-8974. doi: 10.1021/acs.est.3c01151. Epub 2023 Jun 7.
We investigated secondary organic aerosol (SOA) from β-caryophyllene oxidation generated over a wide tropospheric temperature range (213-313 K) from ozonolysis. Positive matrix factorization (PMF) was used to deconvolute the desorption data (thermograms) of SOA products detected by a chemical ionization mass spectrometer (FIGAERO-CIMS). A nonmonotonic dependence of particle volatility (saturation concentration at 298 K, ) on formation temperature (213-313 K) was observed, primarily due to temperature-dependent formation pathways of β-caryophyllene oxidation products. The PMF analysis grouped detected ions into 11 compound groups (factors) with characteristic volatility. These compound groups act as indicators for the underlying SOA formation mechanisms. Their different temperature responses revealed that the relevant chemical pathways (e.g., autoxidation, oligomer formation, and isomer formation) had distinct optimal temperatures between 213 and 313 K, significantly beyond the effect of temperature-dependent partitioning. Furthermore, PMF-resolved volatility groups were compared with volatility basis set (VBS) distributions based on different vapor pressure estimation methods. The variation of the volatilities predicted by different methods is affected by highly oxygenated molecules, isomers, and thermal decomposition of oligomers with long carbon chains. This work distinguishes multiple isomers and identifies compound groups of varying volatilities, providing new insights into the temperature-dependent formation mechanisms of β-caryophyllene-derived SOA particles.
我们研究了 β-石竹烯在大气温度范围内（213-313 K）通过臭氧氧化生成的二次有机气溶胶（SOA）。我们使用正矩阵因子分解（PMF）来解卷积由化学电离质谱仪（FIGAERO-CIMS）检测到的 SOA 产物的解吸数据（热谱）。观察到粒子挥发性（298 K 时的饱和浓度，）对形成温度（213-313 K）的非单调依赖性，主要是由于β-石竹烯氧化产物的形成途径随温度而变化。PMF 分析将检测到的离子分为 11 种具有特征挥发性的化合物组（因子）。这些化合物组是 SOA 形成机制的指标。它们的不同温度响应表明，相关的化学途径（例如自动氧化、低聚物形成和异构体形成）在 213 和 313 K 之间具有明显的最佳温度，远远超过温度依赖性分配的影响。此外，PMF 解析的挥发性组与基于不同蒸气压估算方法的挥发性基础集（VBS）分布进行了比较。不同方法预测的挥发性变化受到高度氧化的分子、异构体和长链低聚物的热分解的影响。这项工作区分了多种异构体并确定了具有不同挥发性的化合物组，为β-石竹烯衍生 SOA 颗粒的温度依赖性形成机制提供了新的见解。
