10th International Aerosol Conference September 2 - September 7, 2018 America's Center Convention Complex St. Louis, Missouri, USA
Abstract View
Probing the Molecular Composition of Model Systems and Secondary Organic Aerosol during Evaporation
DAVID BELL, Veronika Pospisilova, Amelie Bertrand, Houssni Lamkaddam, Chuan Ping Lee, Ruby Marten, Jay G. Slowik, Andre S.H. Prévôt, Urs Baltensperger, Imad El Haddad, Josef Dommen, Paul Scherrer Institute
Abstract Number: 1157 Working Group: Aerosol Chemistry
Abstract Secondary organic aerosol (SOA) makes up a significant fraction of the fine particulate matter in the atmosphere. Because of their prevalence in the atmosphere organic aerosol has a significant impact on human health and the earth’s climate. Therefore, an accurate assessment of the time scale of the aerosol lifecycle is needed to evaluate its impact on the environment. One constraint on the aerosol lifecycle is its volatility. If a particle rapidly evaporates then the impact on the environment will be correspondingly short. However, if organic aerosol consists mainly of low-volatility components, it will not readily evaporate and will be long-lived in the atmosphere, undergo long range transport, and grow large enough to act as cloud condensation nuclei.
Extractive electrospray ionization time-of-flight mass spectrometry (EESI-TOF) is a soft ionization technique and makes it possible to determine the molecular composition of aerosols without fragmentation. Here, we will use EESI-TOF to follow the change in composition of a variety of aerosols during the process of iso-thermal evaporation. We will demonstrate that it is possible to separate changes from wall-losses versus evaporative losses. This technique will be expanded to probe the composition dependent evaporation of ideal multi-component systems and will be compared to their expected volatility. Finally, this method will be applied to complex SOA systems (α-pinene SOA and toluene SOA) generated in atmospheric simulation chambers. Here, we will discuss how the composition of SOA changes as a function of evaporation and aging.