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

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).

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

Aerodyne C-ToF-AMS Aerodyne AMS: Aerodynamic focusing (20 nm < dp < 1000 nm, 100% transmission now 60 - 600 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

Aerodyne Q-AMS

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)

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

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

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)

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

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)

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)

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, kdiehl@uni-mainz.de