The volatility of sub-micrometer atmospheric aerosol particles wasstudied in a rural background environment in Finland using acombination of a heating tube and a scanning mobility particlesizer. The analysis focused on nanoparticles formed throughnucleation which were subsequently observed during their growth inthe diameter range between 5 and 60 nm. During the 6 days of newparticle formation shown in detail, the concentrations of newlyformed particles increased up to 10 000 cm−3. The number ofnucleation mode particles measured after volatilization in theheating tube at 280°C was up to 90% of the total numberunder ambient conditions. Taking into account the absoluteaccuracy of the size distribution measurements, all ambientparticles found in the rural atmosphere could have a non-volatilecore after volatilization at 280°C. As the regional newparticle formation events developed over time as a result offurther vapor condensation, the newly formed particles grew at anaverage growth rate of 2.4±0.3 nm h−1. Importantly, thenon-volatile cores of nucleation mode particles were also observedto grow over time, however, at a lower average growth rate of 0.6±0.3 nm h−1. One implication of the volatility analysisis that the newly formed particles, which have reached ambientdiameters of 15 nm, are unlikely to consist of sulfuric acid,ammonium sulfate, and water alone. A relatively constant ratiobetween the growth rate of the ambient particles as well as theirnon-volatile cores indicates that non-volatile matter is formedonly gradually in the growing particles. The non-volatile fractionof the particles showed some correlation with the ambienttemperature. The composition and formation mechanism of thisnon-volatile material in nucleation mode particles are, to date,not known.
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机译：使用加热管和扫描迁移率粒度仪的组合，研究了芬兰农村背景环境中亚微米级大气气溶胶颗粒的挥发性。该分析集中于通过成核形成的纳米颗粒，随后在其生长过程中观察到直径在5至60 nm之间。在详细显示的6天新颗粒形成过程中，新形成的颗粒浓度增加到10000 cm -3 。在环境条件下，在加热管中于280°C挥发后测得的成核模式颗粒数量高达总数的90％。考虑到尺寸分布测量的绝对准确性，在280°C挥发后，在农村大气中发现的所有环境粒子可能具有不挥发核。随着进一步的水蒸气凝结，随着时间的推移局部新颗粒的形成事件逐渐发展，新形成的颗粒以2.4±0.3 nm h -1 的平均生长速率生长。重要的是，还观察到成核模式颗粒的非挥发性核随时间而生长，但是平均生长速率较低，为0.6±0.3 nm h -1 。挥发性分析的一个含义是，新形成的粒子已经达到15 nm的环境直径，不可能仅由硫酸，硫酸铵和水组成。周围颗粒及其非挥发性核的生长速率之间的相对恒定的比率指示非挥发性物质仅在生长的颗粒中逐渐形成。颗粒的非挥发性部分与环境温度显示出一定的相关性。迄今为止，这种非挥发性材料在成核模式颗粒中的组成和形成机理尚不清楚。
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