AAAR 34th Annual Conference
October 12 - October 16, 2015
Hyatt Regency
Minneapolis, Minnesota, USA
Abstract View
The Sensitivity of a Thermal Desorption Mass Spectrometer to Molecular Weight
DANIEL MURPHY, NOAA CSD
Abstract Number: 215 Working Group: Carbonaceous Aerosols in the Atmosphere
Abstract In free molecular flow, the lower speed of heavier or cooler molecules means that they spend more time in the ion source of a thermal desorption mass spectrometer. Therefore, the sensitivity of a thermal desorption mass spectrometer should scale as the square root of the molecular weight, although thermal fragmentation on the vaporizer may reduce this effect. Residence time in the ion source also depends on the translational temperature of the desorbed molecules. The dependence of sensitivity on molecular weight, fragmentation, and temperature has important implications for interpreting both field and laboratory data from the AMS and similar instruments.