PNNL-13501 - Pacific Northwest National Laboratory

Results and Accomplishments
This project effectively began in May 2000. After
5 months the following progress has been made on the
following five activities:
1. Nuclear Magnetic Resonance Spectroscopy. A
research plan was prepared. Concentrated fogwater
samples collected by the research group of Professor
S. Fuzzi who had attempted similar measurements
(Descari et al. in press) were analyzed for soluble
carbonaceous aerosol constituents (Figure 1). An
aerosol high volume sampler for sample collection
and a continuous PM2.5 aerosol mass sampler for
high time resolution event characterization were
acquired.
Figure 1. A proton decoupled 13 C nuclear magnetic
resonance (NMR) spectroscopy spectrum of fogwater
measured at 75 MHz. The sample was collected in the
polluted Po River valley of Italy. The frequency scale is
expressed as a parts per million (ppm) shift from the
reference 13 C signal of tetramethylsilane (TMS). Inset
spectrum: Expansion of the alcohol region showing the power
of this technique for even higher resolution than displayed.
Identification of compounds by the frequency and their
carbon content by the peaks makes this nondestructive
analysis technique a powerful analytical tool for
characterizing complex organic aerosol mixtures.
2. Volatile Organic Gas Measurements Using Proton
Transfer Mass Spectrometry and Membrane
Separation-Ion Trap Mass Spectrometry.
Collaboration with the world’s leading authority on
proton transfer mass spectrometry was initiated
through a visit by Professor Werner Lindinger (U. of
Innsbruck) to the Laboratory in June 2000. A plan
was developed whereby M. Alexander will make a
technical visit to Prof. Lindinger’s laboratory, we will
acquire a proton transfer mass spectrometer, and a
graduate student of Prof. Lindinger will spend 1 to
2 months at Pacific Northwest National Laboratory in
a collaborative effort to apply the instrument to
aircraft measurements. In late September, an
experienced atmospheric instrumental chemist was
interviewed for a research position that will expedite
the application of this instrumentation.
3. Proton-Induced X-Ray Emission and Proton Elastic
Scattering Analysis of Atmospheric Aerosols. The
tandem ion linear accelerator facility was developed
for high time resolution chemical analysis of
atmospheric aerosols. An exchange of visits with
Professor T. Cahill of the University of California at
Davis and the DELTA group was followed by joint
participation in aerosol collection and comparative
multi-elemental analyses during the Texas 2000 Air
Quality study (August and September 2000). An x-yz
manipulator was installed on the accelerator’s beam
end and tests with artificial aerosol samples were
performed in preparation for analysis of ambient
aerosols. Duplicate analysis of the same samples
from Houston by Pacific Northwest National
Laboratory and the DELTA group will mark the
beginning of our multi-elemental capabilities.
4. High Resolution Individual Particle Analysis System.
This activity involves the analysis of individual
aerosol particles after collection on carbon films
using automated scanning electron microscopy and
on cascade impactor stages by time-of-flight
secondary ion mass spectrometry. Samples from the
Texas 2000 Air Quality study (August and September
2000) were collected. This proposal supported the
time-of-flight secondary ion mass spectrometry
analysis and resulted in a presentation by D. Gaspar
at the American Vacuum Society Annual Meeting.
5. Nucleation Detector for Atmospheric Mercury Vapor.
Proof-of-concept experiments were conducted to
demonstrate the feasibility of two-photon laser
excitation and nucleation detection of elemental
mercury (Figure 2). The methodology shows
sensitivity at better than 0.1 ng Hg /m 3 . Atmospheric
Hg 0 is 1 to 5 ng Hg /m 3 .
Summary and Conclusions
In 5 months, a program of aerosol measurement research
has been initiated within the Fundamental Science
Division of Pacific Northwest National Laboratory. In
this short period, collaborations with two internationally
recognized measurement research groups have been
established and the powerful analytical tools of the
Environmental Molecular Sciences Laboratory mobilized
Earth System Science 243