HR: 09:15h
AN: A51H-05    [Abstracts]
TI: A new instrument for measuring the chemical composition of soot containing particles
AU: * Trimborn, A M
EM: trimborn@aerodyne.com
AF: Aerodyne Research Inc, 45 Manning Rd., Billerica, MA 01821, United States
AU: Kok, G
AF: Droplet Measurement Technologies, 5710 Flatiron Parkway Suite, Boulder, CO 80301, United States
AU: Onasch, T B
AF: Aerodyne Research Inc, 45 Manning Rd., Billerica, MA 01821, United States
AU: Jayne, J T
AF: Aerodyne Research Inc, 45 Manning Rd., Billerica, MA 01821, United States
AU: Trimborn, D
AF: Aerodyne Research Inc, 45 Manning Rd., Billerica, MA 01821, United States
AU: Canagaratna, M
AF: Aerodyne Research Inc, 45 Manning Rd., Billerica, MA 01821, United States
AU: Kroll, J
AF: Aerodyne Research Inc, 45 Manning Rd., Billerica, MA 01821, United States
AU: Williams, L
AF: Aerodyne Research Inc, 45 Manning Rd., Billerica, MA 01821, United States
AU: Cross, E
AF: Boston College, 40 Commonwealth Ave., Chestnut Hill, MA 02467, United States
AU: Hings, S
AF: Boston College, 40 Commonwealth Ave., Chestnut Hill, MA 02467, United States
AU: Davidowitz, P
AF: Boston College, 40 Commonwealth Ave., Chestnut Hill, MA 02467, United States
AU: Baumgartner, D
AF: Droplet Measurement Technologies, 5710 Flatiron Parkway Suite, Boulder, CO 80301, United States
AU: Worsnop, D R
AF: Aerodyne Research Inc, 45 Manning Rd., Billerica, MA 01821, United States
AB: Black carbon containing aerosols play important roles in governing the optical properties of atmospheric aerosol. Absorption of incident solar radiation by elemental carbon containing aerosol leads to atmospheric heating, potentially affecting cloud formation, for example. An outstanding question is the role of coatings on black carbon cores and how such coatings may alter the optical properties of the particles. Instruments such as the Photoacoustic Spectrometer (PASS) and the Single Particle Soot Photometer (SP2) are well suited to characterize total black carbon and the size of black carbon cores in ambient particles (via absorption and incandescence measurements, respectfully). However, these instruments lack the capability to measure the chemical composition of species adsorbed on the black carbon cores. We present a new instrument for measuring the chemical composition of adsorbed inorganic and organic material coating particles containing black carbon. This new instrument couples SP2 laser heating with the aerosol mass spectrometer (AMS). Black carbon containing particles intersect an intense, continuous intracavity laser beam, absorbing the 1064 nm radiation. Vaporized components are then ionized by electron impact ionization and detected using a time of flight mass spectrometric (TOFMS) approach. We report results which demonstrate the utility of this technique for a variety of particles with and without black carbon cores, with and without various coatings. These measurements clearly show that the method is sensitive only for particles containing an absorbing component. The results also show that the mass spectrometric signals vary linearly with the amount of the condensed species. This allows for the quantification and identification of the nonrefractory chemical composition of absorbing particles with the goal of tracking and characterizing primary combustion particles as they are processed and transported in the ambient atmosphere. Signals for vaporized carbon atom clusters are also observed; on-going work is aimed at interpreting the significance of these signals.
DE: 0305 Aerosols and particles (0345, 4801, 4906)
DE: 0394 Instruments and techniques
SC: Atmospheric Sciences [A]
MN: 2007 Fall Meeting