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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. Instrumentation I: Chemical Analysis and Size.
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Single Particle Chemical Characterization andMeasurements of Cloud Condensation NucleiBerko Sierau, Maria MartinETH Zurich, SwitzerlandASCOS Planning WorkshopLandskrona, 8th-10th April 2008
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
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)
Instrumentation III: Single Particle Mass Spectrometry Aerodynamic lens Sizing lasers (532 nm) Desorption/Ionization laser (266 nm)
Instrumentation IV: Measurments of Cloud Condensation Nuclei Properties 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)
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