1. Particle Chemistry Department
Contributions of Uni-MZ to the
Helmholtz Virtual Institute
"Aerosol-Cloud Interactions" (VI-ACI)
J. Schneider, K. Diehl, S. Borrmann
Institute for Atmospheric Physics, Johannes Gutenberg University, Mainz
Max Planck Institute for Chemistry, Mainz
ACI Kick-Off Meeting, FZK, May 14, 2007

2. Aerodyne Aerosol Mass Spectrometer (C-ToF or HR-ToF-AMS),
1) Aerosol and ice particle characterization in work packages 1,2 and 4:
WP L1: AIDA laboratory experiments at Forschungszentrum Karlsruhe
WP L2: LACIS laboratory experiments at IfT Leipzig
WP L4: Chemical characterization of CCN and IN
Instrumentation:
Aerodyne Aerosol Mass Spectrometer (C-ToF or HR-ToF-AMS),
Single Particle Laser Ablation Time-of-Flight MS (SPLAT or ALABAMA).

3. Aerodyne C-ToF-AMS T PC timing controller HV pulser preamp
averaging ADC T
filament
ionization
chamber
aerosol vaporizer
particle ToF measurement
orthogonal
extractor
ion reflector
MCP detector
chopper
aerosol inlet
(aerodynamic lens)
turbo molecular pumps

4. Aerodyne C-ToF-AMS Aerodyne AMS:
Aerodynamic focusing (20 nm < dp < 1000 nm, 100% transmission now nm, future option:  300 – 3000 nm)
Aerodynamic particle sizing
Thermal evaporation (600°C)
Electron impact ionization (70 eV)
Mass concentrations of non-refractory components with high time resolution
Species-resolved size distributions
Advantages of C-ToF-AMS compared to Q-AMS:
High ion duty cycle (Increased sensitivity compared to quadrupole AMS)
Complete size-resolved mass spectra
Quantitative single particle information of non-refractory components

5. Aerodyne Q-AMS

6. 2) Supporting measurements at the wind tunnel of the University of Mainz
Supporting measurement to
WP 1 (AIDA freezing experiments)
WP 3 (ZINC freezing experiments)

7. Vertical wind tunnel at Uni-MZ
plenum chamber
nets and honeycomb
contraction section
experimental section
vacuum pump
sonic nozzle
particle filter
cooling units drying unit

8. Vertical wind tunnel at Uni-MZ
Freezing experiments
freely floating of hydrometeors
no wall effects
controlled temperatures down to -30°C
observation of single freezing events
immersion and contact freezing
plenum chamber
nets and honeycomb
contraction section
experimental section
vacuum pump
sonic nozzle
particle filter
cooling units drying unit

9. Vertical wind tunnel at Uni-MZ
Heterogeneous ice formation: Freezing of super-cooled drops
immersion and contact freezing distinguished by different experimental techniques
immersion freezing:
floating of drops which contain insoluble particles
→ freezing of the drops affected by particles inside
contact freezing:
floating of pure drops and adding of insoluble particles to the tunnel air
→ freezing of the drops after collision with particles outside
observation of single freezing drops in temperature intervals
determination of median freezing temperature Tm
(where 50% of observed drops freeze)

10. Vertical wind tunnel: Results
Immersion freezing: volume dependence
Soot particles from kerosene burner exhaust (Diehl and Mitra, 1998)

11. Vertical wind tunnel: Results
immersion freezing: significantly different effects in dependence of ice nuclei
soot particles from kerosene burner (Diehl and Mitra, 1998)
pollen
(Diehl et al., 2002, v. Blohn et al., 2006)
leaf litter
(Diehl et al., 2001)

12. Vertical wind tunnel: Results
Higher ice nucleation efficiency in contact mode than in immersion mode
Pollen
(Diehl et al., 2002,v. Blohn et al., 2006)

13. Goals contact: Karoline Diehl, kdiehl@uni-mainz.de
Ice nucleation experiments at the Mainz vertical wind tunnel:
Complementary experiments to AIDA, LACIS and ZINC measurements
Effects of ice nuclei in single freezing events
Freezing of super-cooled drops in immersion and contact modes
Determination of median freezing temperature Tm
contact: Karoline Diehl,