Instrumentation Development

Instrument development for the next generation of atmospheric chemistry measurements

Development and characterization of chemical ionization – time-of-flight mass spectrometry for atmospheric measurements

 

Direct, simultaneous measurements of a wide array of trace gases has been made possible by the recent development of a new chemical ionization time-of-flight mass spectrometer (T.H. Bertram et al., 2011).  Over the past few years, in a collaborative project with the University of Washington (Thornton), University of Colorado (Jimenez) Aerodyne Inc. (Billerica, MA), and Tofwerk (Thun, Switzerland), we have developed and characterized a compact, field-deployable CI-TOFMS.  As applied to trace acids, the sensitivity (> 300 counts pptv-1) is an order of magnitude better than that reported for similar quadrupole based instruments (Veres et al., 2008), which we attribute to large, novel advances in the high pressure interface described below.  In the laboratory we have used a host of reagent ions (e.g., C6H6+, NO+, H3O+, I, and CH3C(O)O) to demonstrate the versatility of the system toward detection of a wide array of target molecules.  Details of the instrument can be found in Bertram et al., 2011.  This instrument provides the basis for most of our measurements (e.g., research foci 1 and 2).  We have recently received funding from NASA to fly the instrument as part of a series of summer flights over the next three years.

Representative Publications:

Bertram et al. A field-deployable, chemical ionization time-of-flight mass spectrometer in Atmos. Meas. Tech. Link to the article.

Kim et al., Revisiting benzene cluster cations for the chemical ionization of dimethyl sulfide and select volatile organic compounds in Atmos. Meas. Tech. Link to the article.