Principle of the Measurement
Gas phase: Chemical ionization of VOCs in a VOCUS inlet via proton transfer with hydronium ions (H3O+) or ammonium ion (NH4O+) ligand-switching reactions and detection using a long time-of-flight mass spectrometer
Aerosol phase: The VOCUS Inlet for Aerosols (VIA) front end for thermal desorption of particles into the gas-phase for analysis using the VOCUS LTOF
Aerosol phase: The Extractive Electrospray Ionization (EESI) source is an atmospheric pressure interface for the detailed measurement of aerosol composition
Chemically detailed trace gas composition including small oxygenated compounds (PTR) or highly functionalized S/IVOCs and oxidized VOCs (NH4O+). The VIA and EESI sources measure individual aerosol constituents with a wide range of volatility and oxidation state.
Gas phase: 10Hz
Aerosol phase VIA: 1Hz
Aerosol phase EESI: 1Hz