| Title: | Chemical compositions of black carbon particle cores and coatings via soot particle aerosol mass spectrometry with photoionization and electron ionization |
| Author(s): | Canagaratna MR; Massoli P; Browne EC; Franklin JP; Wilson KR; Onasch TB; Kirchstetter TW; Fortner EC; Kolb CE; Jayne JT; Kroll JH; Worsnop DR; |
| Address: | "daggerCenter for Aerosol and Cloud Chemistry, Aerodyne Research Inc., Billerica, Massachusetts 01821, United States. double daggerDepartment of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States. parallelChemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States. perpendicularEnvironmental Energy and Technologies Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States. #Department of Civil and Environmental Engineering, University of California-Berkeley, Berkeley, California 94720, United States" |
| ISSN/ISBN: | 1520-5215 (Electronic) 1089-5639 (Linking) |
| Abstract: | "Black carbon is an important constituent of atmospheric aerosol particle matter (PM) with significant effects on the global radiation budget and on human health. The soot particle aerosol mass spectrometer (SP-AMS) has been developed and deployed for real-time ambient measurements of refractory carbon particles. In the SP-AMS, black carbon or metallic particles are vaporized through absorption of 1064 nm light from a CW Nd:YAG laser. This scheme allows for continuous 'soft' vaporization of both core and coating materials. The main focus of this work is to characterize the extent to which this vaporization scheme provides enhanced chemical composition information about aerosol particles. This information is difficult to extract from standard SP-AMS mass spectra because they are complicated by extensive fragmentation from the harsh 70 eV EI ionization scheme that is typically used in these instruments. Thus, in this work synchotron-generated vacuum ultraviolet (VUV) light in the 8-14 eV range is used to measure VUV-SP-AMS spectra with minimal fragmentation. VUV-SP-AMS spectra of commercially available carbon black, fullerene black, and laboratory generated flame soots were obtained. Small carbon cluster cations (C(+)-C5(+)) were found to dominate the VUV-SP-AMS spectra of all the samples, indicating that the corresponding neutral clusters are key products of the SP vaporization process. Intercomparisons of carbon cluster ratios observed in VUV-SP-AMS and SP-AMS spectra are used to confirm spectral features that could be used to distinguish between different types of refractory carbon particles. VUV-SP-AMS spectra of oxidized organic species adsorbed on absorbing cores are also examined and found to display less thermally induced decomposition and fragmentation than spectra obtained with thermal vaporization at 200 degrees C (the minimum temperature needed to quantitatively vaporize ambient oxidized organic aerosol with a continuously heated surface). The particle cores tested in these studies include black carbon, silver, gold, and platinum nanoparticles. These results demonstrate that SP vaporization is capable of providing enhanced organic chemical composition information for a wide range of organic coating materials and IR absorbing particle cores. The potential of using this technique to study organic species of interest in seeded laboratory chamber or flow reactor studies is discussed" |
| Keywords: | Aerosols/*analysis Carbon/analysis Cations/analysis Citric Acid/analysis Ethylenes/analysis Fullerenes/analysis Gold Compounds/chemistry Mass Spectrometry/*methods Metal Nanoparticles/chemistry Platinum Compounds/chemistry Silver Compounds/chemistry Soot/; |
| Notes: | "MedlineCanagaratna, Manjula R Massoli, Paola Browne, Eleanor C Franklin, Jonathan P Wilson, Kevin R Onasch, Timothy B Kirchstetter, Thomas W Fortner, Edward C Kolb, Charles E Jayne, John T Kroll, Jesse H Worsnop, Douglas R eng Research Support, Non-U.S. Gov't Research Support, U.S. Gov't, Non-P.H.S. 2014/12/21 J Phys Chem A. 2015 May 14; 119(19):4589-99. doi: 10.1021/jp510711u. Epub 2015 Jan 15" |
