62 1010 Reeves, J. Michael; Kojima, Tomoko; Wilson, James C.; Buseck, Peter University of Denver; Arizona State University Twin Otter MACS Ambient Aerosol Chemical Composition from TEM Analysis CRYSTAL-FACE 1 1 2002 07 18 2003 07 20 0 TEM grid index 7 1.0 1.0 1.0 1.0 1.0 1.0 1.0 999 999 999 999 999 999 999 Ammonium sulfate, percent by number Sea salt, percent by number Sulfates, percent by number Crustal, percent by number Soot, percent by number Other, percent by number Unknown, percent by number 4 1.0 1.0 1.0 1.0 999999 999999 999999 999999 Start time (UT seconds since midnight) Stop time (UT seconds since midnight) Mean particle size, mean of largest 2-D dimension of analyzed particles (micrometers) Number of particles analyzed per grid 4 Grid #4 was too heavily loaded for analysis of individual particles. Listed compositions are estimated percentages by volume, and the 'Other' constituent is mainly zinc. The presence of zinc may indicate spurious particles from the MACS, the Twin Otter inlet, or both. 30 Particles were collected on TEM grids at a fixed sample flow of 54 cm^3/s, constant internal pressure of 300 mb, at 293 to 298 K. The MACS lower cut-point (50% collection efficiency) is approximately 70 nm. Particle sizes were determined from digitized TEM images using a public domain image-analysis software package (NIH Image). The images were obtained at a magnification of 2000 from areas near the impaction center. Particles larger than 100 nm were measurable at this magnification. Chemical composition was determined by energy dispersive spectrometry (EDS) and selected area electron diffraction (SAED). The mean particle size may be biased toward larger sizes because the distribution of particles on the grids is not uniform, with more and larger particles occurring near the impaction centers. Also, aerosol compositions may overestimate sea salt and crustal components as these particles tend to be larger than other types. We have many samples from various flights that have not been analyzed. Grid index numbers and sample times only are reported for these samples. Researchers with interesting problems should contact Tomoko Kojima (Tomoko.Kojima@asu.edu) and/or Peter Buseck (pbuseck@asu.edu) with details. Additional studies would be considered, contingent on commitments, resources, and the magnitude of the effort relative to potential results. Particle classifications are as follows: Ammonium sulfate: Peaks at S and O in EDS spectra. Sea salt: Mainly NaCl; some aggregated with Na-, Ca-, K-, and Mg-sulfates. Sulfates: Na-, Ca-, K-, and Mg-sulfates (excluding those aggregated with NaCl). Crustal: EDS spectra and SAED patterns matching those of clay, feldspar, pyroxene, calcite. Soot: C-rich chain aggregates, SAED pattern of graphite. Other: Metals, oxides, flyash; identified from EDS spectra and morphology. Unknown: Particles that could not be identified. Contact Tomoko Kojima (Tomoko.Kojima@asu.edu) or Michael Reeves (jreeves@du.edu) with questions about the data. 2 55410 55651 999999 999999 999 999 999 999 999 999 999 3 57118 57359 0.77 805 97.76 0.50 0.75 0.37 0.00 0.37 0.25 4 57724 57965 999999 999999 67 999 999 999 999 33 999 5 66601 66842 999999 999999 999 999 999 999 999 999 999 6 72439 72680 999999 999999 999 999 999 999 999 999 999 7 73450 73691 999999 999999 999 999 999 999 999 999 999 8 74717 74958 999999 999999 999 999 999 999 999 999 999