Aerosol and Trace Gases Group (Methods)
The aerosol and trace gas group uses a variety of instruments and methods. These include:
- Nitrate Chemical Ionization-Atmospheric Pressure interface-Time Of Flight mass spectrometer (nitrate CI-APi-TOF) using a long time of flight chamber (LTOF); the instrument is mainly used for the measurement of gas phase sulfuric acid and highly oxygenated organic molecules (HOMs) during laboratory and field studies.
- Water cluster Chemical Ionization-Atmospheric Pressure interface-Time Of Flight mass spectrometer (water cluster CI-APi-TOF) mainly for ammonia, amine and diamine measurements during laboratory and field studies; the instrument is currently modified to a nitrate CI-APi-TOF for aircraft measurements.
- Proton Transfer Reaction-Mass Spectrometer (PTR-MS) using a quadrupole MS for measurement of volatile organic compounds (VOCs)
The group has also developed / uses several instruments, techniques and numeric models:
- Corona ion source generating nitrate reagent ions mainly for ultrasensitive (parts per quadrillion, ppqv, range) sulfuric acid, iodic acid and highly oxygenated organic compound (HOM) measurements.
- Cross-flow corona ion source generating protonated water clusters mainly for ammonia, amine, diamine and iodine species measurement at parts per quadrillion, ppqv, or parts per trillion, pptv, levels.
- Sulfuric acid source for accurate calibration of a nitrate CI-APi-TOF.
- Thermal Desorption-Differential Mobility Analyzer (TD-DMA) combined with a nitrate CI-APi-TOF, which can measure the chemical composition of nano aerosol particles (ca. 5 to 30 nm in diameter) at atmospherically relevant concentrations.
- Condensation particle counter VIPER (VIsual expansion-type Particle counter) using water as condensing fluid for measurement of nano particle concentrations (above ca. 3 nm).
- A flow tube has been set-up for laboratory measurements relating to new particle formation and aerosol growth.
- Sulfuric acid Ammonia NucleaTIon And GrOwth (SANTIAGO) numeric process model for calculation of new particle formation and growth rates from sulfuric acid, water and ammonia.
Furthermore, a set of particle counting and sizing instruments as well as trace gas monitors are used to conduct field measurements and to characterize other instruments.