科研之友
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摘要
Single particle mass spectrometer (SPAMS) can be used to determine the size and chemical compositions of single particles rapidly in real-time, while no need for sample pretreatment and avoiding the change of the sample components. In this study, homemade SPAMS was used to study the signatures of diesel exhaust particles. The fresh emitted particles were analyzed firstly. The fresh particles collected in the suction flask were then reanalyzed after 15-hour aging. Results showed that fresh emitted particles were mainly composed by elemental carbon (EC), organic carbon (OC), calcium phosphate (Ca-Phosphate), sodium and potassium mixing with elemental carbon (NaK-EC), potassium mixing with secondary (K-Secondary) and polycyclic aromatic hydrocarbons (PAH), with diameters concentrating in less than 300 nm. Aged particles had a broader size distribution than that of fresh particles and were composed by EC and OC mixing with secondary species (OCEC-Secondary), EC containing only positive mass spectra, K-Secondary, OC, NaK-EC, metal containing (Metal) particles. Aged particles mix with secondary species including organics, nitrate, sulfate, ammonium in the atmosphere. This study has reference sense for domestic engine manufacture, oil processing, catalyst performance study and environmental particles apportionment.
