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 is designed to measure 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 react with the target species through an adduct formation process and are then detected with a high-resolution mass spectrometer. Strat-CIMS was designed to operate in harsh environments like low ambient pressure (60 mbar) and temperatures (190K). It has a response time of less than 1 second and an accuracy of approximately 15 to 30%, depending on the species.