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39.
Combined Operation of an Aerodynamic Particle Sizer and a Laser
Based Single Particle Mass Spectrometer
S.
Gallavardin(1), T. Ferge(2), and Ralf Zimmermann(3)
(1)GSF Forschungszentrum, Institut für Ökologische Chemie,
Ingolstädter Landstr. 1, 85764 Neuherberg, Germany
(2)BIfA-Bayerisches Institut für Angewandte Umweltforschung
und -technik GmbH, Abteilung Umweltchemie und Prozessanalytik,
Am Mittleren Moos 46, D-86167 Augsburg, Germany
(3)Analytische Chemie, Institut für Physik, Universität
Au gsburg, Universitätsstraße 1, D-86159 Augsburg,
Germany
* Corresponding author, e-mail: ralf.zimmermann@gsf.de
Keywords:
on-line, single particle, chemical characterization, mass spectrometer.
Introduction
A recent study (Zimmermann et al., 2003) showed the interest of
operating a single particle mass spectrometer in order to state
about the mixing state of an aerosol and about the dependency
of the aerosol composition as a function of its size distribution.
Such analyses are required in order to better identify the aerosol
sources and their formation processes. An aerosol time-of-flight
mass spectrometer (ATOFMS) has been build at GSF-Forschungszentrum
and is operated simultaneously with an Aerodynamical Particle
Sizer (APS 3320, TSI Inc.) to get a “complete” description
of the aerosol being examined. The experimental set-up is presented
here.
Experimental Set-Up (see Fig.1)
The aerosol stream is split in two streams: one
leading to the APS and the other one to the aerosol mass spectrometer.
The particle is sampled in the ATOFMS by the inlet system (1).
The particle is then sized in the module (2) according to the
APS principle. This module detects the particle and calculate
the time at which the particle will reach the center ion source
region (3). At this time, a pulsed laser (337 nm) is fired. The
energy of the laser pulse (fluence 1010 W/cm2 ) in the ion source
(3) volatilizes and ionizes the constituents of the particle.
The resulting ions are then analyzed immediately in a bipolar
mass spectrometer (4) in linear or reflectron mode.
First results.
The ATOFMS is now operated with a dynamic sizing system which
provides the size and information about the chemical composition
of the single particle being analyzed, here, particle from flame
soot. In Fig.2 is presented the size information of the particle,
given by Particle TOF = 41 µs (corresponding to a aerodynamical
diameter of ca. 1,9 µm after our calibration). Thus the
negative mass spectra (see time series (MS[-])), which shows many
anionic carbons clusters, indicate the presence of carbonaceous
material in the particle.
Further developments
In a next future, a two-step laser ionization approach will be
implemented in order to focus on the analysis of organic material
in aerosols.
Reference: Zimmermann, R., Ferge,
T., Gälli, M., Karlsson, R., (2003), Rapid Communications
in Mass Spectrometry, 17, 851-859
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