Description: Das Projekt "Analysis of the chemical composition of nucleating clusters with Atmospheric Pressure Interface Time of Flight Mass Spectrometry" wird vom Umweltbundesamt gefördert und von Paul Scherrer Institut, Labor für Atmosphärenchemie durchgeführt. Aerosols and clouds are recognized as representing the largest uncertainty in the current un-derstanding of climate change. Aerosols affect the climate by directly absorbing or scattering the solar radiation. Particles with diameters larger than ca50-100 nm can act as cloud conden-sation nuclei (CCN) and influence the lifetime and optical properties of clouds. Based on cur-rent model estimates, about 40-70Prozent of cloud drops in the present-day global atmosphere are formed on aerosol particles that were created through the process of nucleation. Thus, nuclea-tion is likely to be a major factor controlling changes in the radiative properties of clouds. It is also speculated that cosmic rays have an influence on clouds via a significant contribution of ion-mediated nucleation to the overall source strength of aerosol particles in the atmosphere. However, regarding this step there are large discrepancies in the recent literature. To date, most global climate models use very simple parameterizations of nucleation. However, to make reliable predictions of long-term changes in atmospheric aerosol, and hence past or future cli-mate forcing, a more fundamental understanding of particle formation processes is needed. Progress in this field was hampered by the fact that the capability to measure the aerosol chemical composition of particles in the range of a few nanometers was missing. Just now, the Atmospheric Pressure Interface Time of Flight Mass Spectrometer (APi-TOF MS) has been de-veloped by TOFWERK (Junninen et al., 2010). This instrument measures directly the mass spectra of ambient ions and ion clusters at their natural abundance. Typical naturally charged ion concentrations are around 100-1000 cm-3 per polarity, which indicates the extremely high sensitivity of the instrument. Moreover, TOFWERK has now even coupled an ion mobility spec-trometer (IMS) to the APi-TOF (System 1.0 IMS-HTOF). Thus, ions are separated according to their shape-to-charge ratio before their mass-to-charge is measured in the TOF MS. The addi-tion of an ion mobility cell to a mass spectrometer improves separation of isomers, isobars and conformers and adds a new dimension to the mass spectrometer. This proposal asks for support of an IMS-APi-TOF. The accurate measurement from the APi-TOF in combination with the additional information from the IMS will help to unambiguously resolve the atomic composition of clusters involved in new particle formation. This instrument is vital to unravel fundamental physical and chemical processes involved in new aerosol parti-cle formation and growth. It is our aim to better understand the new particle formation and to develop a mechanistic framework for this process. This will contribute to the reduction of un-certainties with regard to the influence of aerosols on climate change. (...)
SupportProgram
Origin: /Bund/UBA/UFORDAT
Tags: Wolkenbildung ? Luftdruck ? Außenluft ? Atmosphärisches Aerosol ? Wasserdampf ? Absorption ? Aerosol ? Chemische Zusammensetzung ? Eis ? Massenspektrometrie ? Partikelgrößenverteilung ? Gasförmiger Stoff ? Globales Klimamodell ? Ionen ? Isomer ? Kondensation ? Physikalisches Modell ? Messung ? Chemisches Verfahren ? Klimawandel ? Kondensationskern ? Partikel ? Arbeit ? Solarstrahlung ? Atmosphäre ? Ballungsraum ? Laboruntersuchung ? Chemische Reaktion ? Physikalischer Vorgang ? Kosmische Strahlung ? Atmosphärischer Prozess ? Smogkammer ? cloud condensation nuclei (CCN) ? Nanobereich ? cluster ? mass spectrometer ? nucleation ?
License: cc-by-nc-nd/4.0
Language: Englisch/English
Time ranges: 2012-12-01 - 2013-11-30
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