AAAR 32nd Annual Conference
September 30 - October 4, 2013
Oregon Convention Center
Portland, Oregon, USA
Abstract View
TPD Aerosol-CIMS – Investigating the Volatility of Organic Salts
SILJA HÄKKINEN, Joseph Woo, Greg Drozd, V. Faye McNeill, Columbia University
Abstract Number: 310 Working Group: Aerosol Chemistry
Abstract Understanding aerosol volatility, i.e. aerosol partitioning between gaseous and particulate phases, is important in order to accurately determine total atmospheric aerosol loadings and furthermore assess the climatic effect of aerosols. It is known that atmospheric organics have a significant contribution to the mass of aerosol particles. The lower the volatility, the more likely it is that an organic species will partition to aerosols, including the very smallest particles. We demonstrate here the use of TPD Aerosol-CIMS (Temperature Programmed Desorption Aerosol-Chemical Ionization Mass Spectrometry) to investigate the volatility properties of the aerosols under laboratory conditions. We generated low-volatility oxalate salt aerosols via the reactive uptake of oxalic acid to CaCl$_2 particles in an aerosol flow tube reactor as well as by atomizing a solution of sodium oxalate. The TPD Aerosol-CIMS was used to demonstrate the depressed volatility of these particles compared to pure oxalic acid aerosols. As in the Aerosol-CIMS technique, aerosols are passed through a heated flow tube inlet and the volatilized organic compounds are ionized chemically and detected using a quadrupole mass spectrometer. In the TPD Aerosol-CIMS, the inlet temperature is varied between room temperature and 180 degrees Celsius while tracking the evaporation of the organic species of interest. TPD Aerosol-CIMS measurements yield information about the gas-particle partitioning of individual compounds in the studied aerosol, including their effective heat of vaporization.