Mixing state of size selected submicronmeter particles during photochemical and combustion events measured with the tandem system

Abstract

A hygroscopicity tandem differential mobility analyzer (HTDMA) system with a thermodenuder (heated tube and charcoal absorber) was applied to determine mixing state of atmospheric ultrafine particles at urban Gwangju in Korea when ultrafine particle events were produced. Core-shell mixing state was determined by indentifying existence of non-volatile core after removing volatile species with increasing temperature up to ~250 oC. Data showed that in the combustion event ultrafine particles exist as core-shell mixture (i.e., non-volatile core coated with some volatile species) while in the photochemical event there was no such non-volatile core. particle events were produced. Core-shell mixing state was determined by indentifying existence of non-volatile core after removing volatile species with increasing temperature up to ~250 oC. Data showed that in the combustion event ultrafine particles exist as core-shell mixture (i.e., non-volatile core coated with some volatile species) while in the photochemical event there was no such non-volatile core.