1. AEROSOL MASS SPECTROMETRY
Cloud Physics and Chemistry Department (CPCD)
AEROSOL MASS SPECTROMETRY
Application of the Aerodyne AMS in various field studies
Johannes Schneider
Department of Cloud Physics and Chemistry Max Planck Institute for Chemistry / University of Mainz, Germany

2. Outline The Cloud Physics and Chemistry Department at Mainz
The Aerodyne Aerosol Mass Spectrometer (AMS)
Ground based aerosol measurements (MINOS, Crete, August 2001)
Aircraft based aerosol measurements (PAZI, May 2003)
Diesel exhaust measurements
Cloud residual particle measurements: Åreskutan/Sweden (Juli 2003) and Jungfraujoch/Switzerland (CLACE-3, March 2004)
Summary / Answers to leading questions

3. Cloud Physics and Chemistry Department (CPCD)
Head: Prof. Dr. Stephan Borrmann
Research Groups:
Johannes Schneider
Subir Mitra
Aerosol Mass Spectrometer (AMS) Field Campaigns
Vertical Wind Tunnel (Rain Droplet and Ice Crystal Research)
Frank Drewnick
Joachim Curtius
Time-of-flight Aerosol Mass Spectrometry (Instrument Development)
Ion Trap Aerosol Mass Spectrometry (Instrument Development) High Altitude Aircraft Particle Measurements
Max Planck Institute
University

4. The Aerodyne Aerosol Mass Spectrometer AMS
Vaporizer
( 600 °C)
Einlass: aus umgebender Atmosphäre durhc 0.1 mm kritische Düse, dann aerodynamisch Linse.
Strahl wird fokussiert, trifft nach 39 cm auf Vaporizer, T = 400 – 700 °C, variabel.
Volatiel und semivolatile ("non–refractory") Bestandeteile verdampfen, Ionisation des Gases mit Elektronenstoß (70eV), dann Analyse im Quadrupol-MS (16 mm ,Balzers)
Chopper: rotiert mit ca. 100 Hz, kann benutzt werden um Größenverteilung zumessen, indem MS auf eine Masse gesezt wird (z.B. 48 SO+) für Sulfat.

5. AMS - Modes of Operation
Time-of-flight mode
Mass size distribution for various m/z‘s as a function of “vacuum aerodynamic diameter“ (Dva).
Mass spec mode
Continuous scanning of mass range
Quantitative chemical composition (non-refractory)
Transmission
dM/dlog(Dva)
Ion Rate (Hz)
Vacuum aerodynamic diameter (nm)
Vacuum aerodynamic diameter
m/z

6. Mediterranean INtensive Oxidant Study Crete, August 2001
MINOS
Mediterranean INtensive Oxidant Study Crete, August 2001
Crete
from: Lelieveld, J., et al., Global air pollution crossroads over the Mediterranean, Science, 298, ,

7. Aerosol is dominated by sulfate.
MINOS - Time Series
Aerosol wird von Sulfat dominiert, nur teilweise neutralisiert von Ammonium
-> Bildung von Ammoniumnitrat nicht möglich (auch wegen hoher Temperatur, aber hauptsächlich wegen Mangel an Ammonium)
-> Passt zu den niedrigen Nitratwerten.
Organische Komponenten zeigen längere atmosphärsiche Verweilzeiten (photochemische Konversion) -> Beleg für Transport von weiter her (3-4 Tage)
Schneider et al., Atmos. Chem. Phys., 4, 65-80, 2004.
Aerosol is dominated by sulfate.
Fossil fuel combustion in Middle and Eastern Europe influences Eastern Mediterranean.

8. MINOS - Size Distributions
MOUDI: Impactor with subsequent filter analysis
Comparison between MOUDI and AMS: good agreement for sulfate and ammonium, AMS has better detection limit than MOUDI
Better time resolution of AMS (Minutes  Hours)
Schneider et al., Atmos. Chem. Phys., 4, 65-80, 2004.

9. Aircraft-based measurements
First employment of an AMS on a jet aircraft (DLR-Falcon)
(PAZI) Particles From Aircraft: Impact on Cirrus Clouds and Climate,
May 2003, Oberpfaffenhofen, Germany

10. AMS aircraft configuration

11. Aircraft Inlet
M. Fiebig, Ph.D. Thesis, 2001

12. Pronounced boundary layer on flight #1
Vertical Profiles
Flug 1: klar ausgeprägte Grenzschicht, Maximum der Organics am oberen Rand der Grenzschicht
Flug 2: anscheinend mehr Konvektion, Grenzschicht weniger stark ausgeprägt.
Nitrat nimmt stärker ab mit der Höhe als Sulfat.
An der Tropopause liegen die Werte etwa bei der Nachweisgrenze des Instruments
Pronounced boundary layer on flight #1
Time resolution: 1 min sampling, averaged by altitude bins

13. Size distributions 3000 m 6000 m Daten aus Flug 2.
Bimodale Verteilung von Sulfat, verschiebt sich zu kleineren Duchmessern in größerer Hohe.
Nitrat monomodal

14. Diesel exhaust particles
Chassis dynamometer test facility of the Ford Research Center Aachen

15. Nucleation particles I
High FSC, w/o thermodenuder
High FSC, with thermodenuder
Low FSC, w/o thermodenuder

16. Individual car chasing
Individual car chasing on test track
AMS in Ford Mobile Lab
Distance 10 m, various speeds and FSCs

17. Nucleation Particles II
J. Schneider et al., Nucleation particles in Diesel exhaust: Composition inferred from in-situ mass spectrometric analysis, to be submitted to Env. Sci. Techn., May 2004.

18. Cloud residual particles
SOACED (Sources and Origins of Atmospheric Cloud Droplets)
Åreskutan / Sweden (July 2003) 1250 m asl., 63.4°N, 13.1°E
CLACE-3 (Cloud and Aerosol Characterization Experiment)
Jungfraujoch / Switzerland, (March 2004) 3580 m asl., 46.55°N, 7.98°E

19. Cloud particle sampling
Total
aerosol
Sampling
Ice crystals
Interstitial
aerosol
CVI
Residuals
Ice nuclei
Cloud droplets Interstitial aerosol

20. Warm cloud (Sweden, July)
Interstitial Particles
Residual particles slightly larger than interstitial particles (average: +60 nm).
Activation of nitrate down to 150 nm, other species down to 200 nm
Relative enrichment of nitrate and ammonium compared to organics and sulfate
Cloud Residual Particles

21. Ice cloud (preliminary results)
Interstitial Particles
Low concentration of non-refractory material in ice nuclei (CVI enrichment ca. 10)
Nitrate activated down to 250 nm, sulfate down to 300 nm
Relative enrichment of sulfate compared to nitrate
CVI residuals

22. Supercooled cloud (preliminary results)
Interstitial Particles
Almost all particles activated as CCN
interstitial aerosol almost depleted (from SPMS: activation from 70 nm on)
Nitrate and sulfate similar
CVI residuals

23. Summary Answers to leading questions I
The AMS as one representative of "new directions" – what can be learned ?
Good time resolution, quantitative information, quasi-simultaneous composition and size distribution (however, non-refractory PM only)
Quantification needs laboratory work and additional information
Time resolution -> suited for aircraft-based measurements
Coupling of CVI and MS offers insight into cloud formation processes

24. Summary Answers to leading questions II
Mass spectrometric techniques may move into mainstrem monitoring in future (ca. 10 years) (Several issues still to be solved)
Missing:
Quantitative measurement of refractory components (Quantitative Single Particle Laser Ablation MS)
Quantitative non-refractory single particle information -> Aerodyne ToF-AMS
Identification of unknown mass peaks (organics) -> Ion trap - AMS
Extend size ranges!  5 nanometers (nucleation) to  50 micrometers (clouds)

25. Acknowledgments
Frank Drewnick, Nele Hock, Silke Henseler, Silke Weimer, Saskia Walter, Joachim Curtius, Andreas Kürten, Matthias Ettner, Thomas Böttger, Stephan Borrmann
Jos Lelieveld et al. (Crete campaign) Ulf Kirchner et al., (Ford Research Center) Bernd Kärcher et al. (PAZI aircraft campaign) Kevin Noone et al. (Areskutan) Ernest Weingartner et al. (Jungfraujoch) Doug Worsnop et al. (Aerodyne)