Abstract The partitioning of semi-volatile organic compounds (SVOCs) between particle and gas phases is a primary focus in the study of the formation and lifetime of secondary organic aerosols (SOAs). To predict the temporal and spatial distribution of SOAs, it is essential to retrieve the fundamental parameters of SVOCs that govern the distribution of organic compounds between the condensed and gas phases. In the present work, the volatility of 1,2,6-hexanetriol in sucrose/1,2,6-hexanetriol/water mixed aerosol droplets was studied by employing optical tweezers coupled with cavity-enhanced Raman spectroscopy. The radii and refractive indexes of the levitated droplets were determined in real time using the wavelength positions of stimulated Raman spectra, and the effective vapor pressures of 1,2,6-hexanetriol at different relative humidity (RH) were obtained according to Maxwell equation. For the droplets with sucrose/1,2,6-hexanetriol molar ratio of 1:1, the effective vapor pressure of 1,2,6-hexanetriol decreased with the decrease of RH. When the RH decreased from 70% to 10%, the effective vapor pressure of 1,2,6-hexanetriol decreased from (2.16 ± 0.229 ) × 10 − 4 P a to (6.72 ± 0.7 ) × 10 − 6 P a . Compared to the vapor pressure of pure 1,2,6-hexanetriol (1.16 ± 0.025) × 10 − 4 P a ~ ( 3.82 ± 1.16 ) × 10 − 4 P a , the evaporation of 1,2,6-hexanetriol in the mixed droplet was suppressed by sucrose, especially at low RH. For the mixed droplets with sucrose/1,2,6-hexanetriol molar ratio of 3:1, 1:3, a similar phenomenon was observed. Besides, for the mixed droplets under constant RH, the effective vapor pressure of 1,2,6-hexanetriol decreased with the sucrose increasing, and the presence of 1,2,6-hexanetriol caused viscosity decline of sucrose in the meantime. To characterize the water mass transfer of mixed droplets at different RH, the characteristic time ratios between the droplet radius and the RH were calculated. Compared to the characteristic time ratio of pure sucrose droplets, the characteristic time ratio of the mixed droplets apparently decreased. And for constant RH, the characteristic time of sucrose/1,2,6-hexanetriol/H2O decreased with the increase of 1,2,6-hexanetriol. In general, we report the studies of both volatility and molecular diffusion process in the aerosol phase for the sucrose/1,2,6-hexanetriol/H2O ternary system, these results may provide a theoretical basis for subsequent research concerning the volatility of SVOCs in super viscous aerosols.

中文翻译：

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悬浮的粘性气溶胶颗粒中 1, 2, 6-己三醇的挥发性测量

摘要 半挥发性有机化合物 (SVOC) 在颗粒相和气相之间的分配是二次有机气溶胶 (SOA) 形成和寿命研究的主要焦点。为了预测 SOA 的时间和空间分布，必须检索 SVOC 的基本参数，这些参数控制着冷凝相和气相之间的有机化合物的分布。在目前的工作中，1,2,6-己三醇在蔗糖/1,2,6-己三醇/水混合气溶胶液滴中的挥发性通过使用光镊结合腔增强拉曼光谱进行了研究。悬浮液滴的半径和折射率使用受激拉曼光谱的波长位置和 1,2 的有效蒸气压实时确定，根据麦克斯韦方程得到不同相对湿度(RH)下的6-己三醇。对于蔗糖/1,2,6-己三醇摩尔比为1:1的液滴，1,2,6-己三醇的有效蒸气压随着RH的降低而降低。当相对湿度从 70% 降低到 10% 时，1,2,6-己三醇的有效蒸气压从 (2.16 ± 0.229 ) × 10 - 4 Pa 降低到 (6.72 ± 0.7) × 10 - 6 Pa。与纯 1,2,6-己三醇的蒸气压 (1.16 ± 0.025) × 10 − 4 Pa ~ ( 3.82 ± 1.16 ) × 10 − 4 Pa 相比，1,2,6-己三醇在混合液滴被蔗糖抑制，特别是在低 RH 下。对于蔗糖/1,2,6-己三醇摩尔比为3:1、1:3的混合液滴，观察到类似的现象。此外，对于恒定 RH 下的混合液滴，有效蒸气压为 1,2，6-己三醇随蔗糖的增加而减少，同时1,2,6-己三醇的存在导致蔗糖粘度下降。为了表征不同RH下混合液滴的水传质，计算了液滴半径与RH之间的特征时间比。与纯蔗糖液滴的特征时间比相比，混合液滴的特征时间比明显降低。而对于恒定RH，蔗糖/1,2,6-己三醇/H2O的特征时间随着1,2,6-己三醇的增加而减小。总的来说，我们报告了蔗糖/1,2,6-己三醇/H2O三元体系气溶胶相中挥发性和分子扩散过程的研究，