Strat-CIMS
High Altitude Chemical Ionization Mass Spectrometer

The High Altitude Chemical Ionization Mass Spectrometer (Strat-CIMS) is an in situ airborne mass spectrometer operated by NOAA. It measures gas-phase inorganic and organic species in the upper troposphere and lower stratosphere. The instrument's ion source uses a photoionization krypton lamp operating in the vacuum ultraviolet (VUV) range (124 and 117 nm) to produce iodide ions. These ions form adducts with the target species and are then detected by a high-resolution mass spectrometer. Strat-CIMS was designed to operate in harsh environments, including low ambient pressure (60 mbar) and low temperatures (190K). It has a response time of less than 1 second and an accuracy of approximately 15 to 30%, depending on the species.