1. ASCOS planning meeting, 8 th April 2008 IAC ETH Single Particle Chemical Characterization and Measurements of Cloud Condensation Nuclei Berko Sierau, Maria Martin ETH Zurich, Switzerland ASCOS Planning Workshop Landskrona, 8 th -10 th April 2008

2. ASCOS planning meeting, 8 th April 2008 IAC ETH Instrumentation I: Chemical Analysis and Size Online chemical characterization of individual aerosols using the Aerosol-Time-of-Flight Mass Spectrometer (ATOFMS, TSI-3800) Aerodynamic Sizing  Sample polydisperse aerosol  NOT a scanning technique  Determine size distribution of aerosol (250 nm – 3000 nm) by composition by time 2

3. ASCOS planning meeting, 8 th April 2008 IAC ETH Instrumentation II: Chemical Analysis Time-of-Flight Mass Spectrometry  Positive and negative ion mass spectra of single particles  Complete mass spectra of each particle  Mass spectra indicate particle composition  Both non-volatile and semi-volatile compounds can be detected  Detection of refractory material (sea salt aerosol, soot) cp. to AMS  Non-quantitative measurement (parallel measurements of Aerodyne- MS is an important addition) 3

4. ASCOS planning meeting, 8 th April 2008 IAC ETH Instrumentation III: Single Particle Mass Spectrometry 4 Desorption/Ionization laser (266 nm) Sizing lasers (532 nm) Aerodynamic lens

5. ASCOS planning meeting, 8 th April 2008 IAC ETH Instrumentation IV: Measurments of Cloud Condensation Nuclei Properties 5 Measurement of CCN-active fraction of the ambient aerosol using the Cloud Condensation Nuclei Counter (CCNC; DMT, Boulder, USA)  Supersaturation range 0.1-2%, 30 second supersaturation change  CCN activation ratio and concentration measured as a function of water vapor saturation  CCN activation ratio and concentration measured as a function of particle diameter  CCN activation ratio and concentration of one particle diameter and at one supersaturation as a function of time (standard measurement procedure can be extended as a second CCNC will be provided)

6. ASCOS planning meeting, 8 th April 2008 IAC ETH Instrumentation V: CCN Counter, Mode of Operation

7. ASCOS planning meeting, 8 th April 2008 IAC ETH Open Questions / Discussion Operational mode of CCNC ?  Measurement of size-segregated CCN properties only possible if a DMA is employed upstream of the instrument (not provided by ETH)  Routine calibration of CCNC using DMPS system employed for standard size distribution measurements?  CCNC and IN chamber on common inlet as they share a CPC upstream of the instrument 7