61 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 19 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
3
This file contains ONLY grid index numbers and sample times.
No grids from this flight have been analyzed.  See the normal
comments regarding possible analysis of grids from this flight.
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.

1 56366 56607 999999 999999
999 999 999 999 999 999 999
3 60131 60372 999999 999999
999 999 999 999 999 999 999
4 69432 69673 999999 999999
999 999 999 999 999 999 999
5 71555 71796 999999 999999
999 999 999 999 999 999 999
6 74878 75119 999999 999999
999 999 999 999 999 999 999
7 79122 79363 999999 999999
999 999 999 999 999 999 999
8 80961 81202 999999 999999
999 999 999 999 999 999 999
9 82465 82706 999999 999999
999 999 999 999 999 999 999