Post on 27-Jan-2021
Potential Aerosol Mass (PAM)flow reactor updates
• Andy Lambe, Tim Onasch, Paola Massoli, DavidCroasdale, Justin Wright, Adam Ahern, Leah
Williams, Doug Worsnop, Bill Brune, Paul DavidovitsBoston College / Aerodyne / Penn State
AMS Userʼs Meeting, Oct 2011, Orlando
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PAM overview• Flow tube reactor developed by Bill Brune
– lower surface-to-volume ratio than other flow tubes• OH exposures ranging from (1-20)×1011 molec cm-3 s• Applications as technique for SOA generation/aging
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f44-f43 triangle plot of PAM SOA/OPOA
• PAM measurements define a larger f43 - f44 triangle with oxalic acid asan oxidation endpoint
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Van Krevelen Diagram of PAM SOA/OPOA
• Dotted lines: range of ambient AMS measurements (Ng et al, ACP, 2011)
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Correlation of hygroscopicity (κCCN) with O/C ratio
• Extends work of Massoli et al (GRL, 2010)• Good agreement with previous OOA hygroscopicity studies
κ CC
N
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Studies using the PAMtechnique
• Kang et al., ACP, 2007• Massoli et al., GRL, 2010• Lambe et al., AMT, 2011• Kang et al., ACP, 2011• Lambe et al., ACP, 2011• Cubison et al., ACPD, 2011
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Main PAM issues
Lambe et al.,AMT, 2011
Residence time distributions Wall losses
Lambe et al.,AMT, 2011
Unfortunately, all laboratory reactors have flaws. In spite ofthese issues, we can make relevant measurements.
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SOA/OPOA precursors we’ve studied
Pennzoil
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Correlation of α-pinene SOA with ambientHOA, SV-OOA & LV-OOA
• HOA, SV-OOA, and LV-OOA factors from Ng et al. (ES&T, 2011)
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An example of “HOA-like” SOA