Surface chemical characterization of 2.5-microm particulates (PM2.5) from air pollution in Salt Lake City using TOF-SIMS, XPS, and FTIR.
Particulate matter with a diameter of 2.5 microm collected in Salt Lake City (SLC PM2.5) was studied using TOF-SIMS (time-of-flight secondary-ion mass spectrometry), XPS (X-ray photoelectron spectroscopy), and FTIR (Fourier transform infrared spectroscopy). The high spatial resolution and high surface sensitivity of TOF-SIMS allow the surfaces of individual particulates to be analyzed. The high mass-resolution of TOF-SIMS provides good separation of signals from different chemical species at the same nominal mass, and the extremely high detection sensitivity of TOF-SIMS makes the detection of trace elements possible. Metallic elements such as Li, Na, Mg, Al, K, Ca, Cr, Mn, Fe, Cu, Zn, Cs, and Bi were detected by TOF-SIMS on the surface of SLC PM25. The uranium ion U+ together with its oxide ions UO+ and UO2+ were also found. Inorganic compounds detected include oxides, hydroxides, nitrates, sulfates, silicates, borates, chlorides, etc. Organic compounds detected include hydrocarbons, alcohols, aldehydes, ethers, carboxylic acids, amines, amides, nitriles, etc. A number of polycyclic aromatic hydrocarbons (PAH) and nitrated polycyclic aromatic hydrocarbons were detected by TOF-SIMS. High-resolution XPS Cls spectrum shows functional groups such as C-O, CO2, C-CO2, C-C, and C-H and aromatic pi-pi* shake-up transitions. High-resolution XPS O 1s spectrum indicates the coexistence of different oxygen compounds on the surface of PM2.5. FTIR results confirm the presence of various organic compounds in SLC PM2.5 detected by TOF-SIMS and XPS.
Zhu
Y J
YJ
Department of Chemistry and Surface Analysis Facility, University of Utah, Salt Lake City 84112, USA.
Olson
N
N
Beebe
T P
TP
D000393:Air Pollutants / Q000032:analysis*; D002947:Cities; D004784:Environmental Monitoring / Q000379:methods*; D006838:Hydrocarbons / Q000032:analysis; D013058:Mass Spectrometry; D010100:Oxygen / Q000032:analysis; D010316:Particle Size; D017550:Spectroscopy, Fourier Transform Infrared; D014131:Trace Elements / Q000032:analysis
D000393:Air Pollutants; D006838:Hydrocarbons; D014131:Trace Elements; D010100:Oxygen