Tropospheric Chemistry: VOC Instruments

Long Time-of-Flight Chemical Ionization Mass Spectrometer (LTOF-CIMS) with optional VOCUS Inlet for Aerosols (VIA) or Extractive Electrospray Ionization (EESI)

schematic
LTOF-CIMS: one instrument for VOC PM composition - partitioning - highly oxidized VOCs

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

Species Measured

LTOF-CIMS

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.

Time Response

Gas phase: 10Hz
Aerosol phase VIA: 1Hz
Aerosol phase EESI: 1Hz

Manufacturer

TOFWERK Vocus

Field Projects

Secondary organic aerosol Chamber Experiments for Non-Traditional Species (SCENTS) 2022

Southwest Urban NOx and VOC Experiment (SUNVEx) 2021