News & Events

Steven Sjostedt, Ph.D.

Posted on February 5, 2016


Date - February 5, 2016
1:00 pm


Research Scientist II
NOAA Earth System Research Laboratory,
Chemical Sciences Division

“In situ measurement of trace gases and radicals using Chemical Ionization Mass Spectrometry”


The study of air pollution has historically focused on the formation of photochemical smog (O3) and particulate matter (PM 2.5). The oxidation of volatile organic compounds (VOCs) by hydroxyl radicals (OH) contributes to the formation of both through multi-step processes.  However, the measurement of some trace gases and the HOx radical family (OH + hydroperoxy radical (HO2) the reservoir species) has proven challenging due to low concentrations and short lifetimes.

Chemical Ionization Mass Spectrometry (CIMS) provides a measurement technique that can provide the sensitivity and time resolution required.  Furthermore, a wide array of atmospherically relevant traces gas can be measured by (CIMS). The species analyzed are dependent on the ion chemistry utilized. The implementation and operation of CIMS to measure in a variety of field sites will be discussed.