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