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Developing an absorption spectrometer for the simultaneous measurement of HONO and NO 2

Developing an absorption spectrometer for the simultaneous measurement of HONO and NO 2. Ben H. Lee 1 , Greg W. Santoni 1 , J. William Munger 1 , Steven C. Wofsy 1 , Ezra C. Wood 2 , Scott C. Herndon 2 , J. Barry McManus 2 , David D. Nelson 2 , Richard C. Miake-Lye 2 and Mark S. Zahniser 2.

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Developing an absorption spectrometer for the simultaneous measurement of HONO and NO 2

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  1. Developing an absorption spectrometer for the simultaneous measurement of HONO and NO2 Ben H. Lee1, Greg W. Santoni1, J. William Munger1, Steven C. Wofsy1, Ezra C. Wood2, Scott C. Herndon2, J. Barry McManus2, David D. Nelson2, Richard C. Miake-Lye2 and Mark S. Zahniser2 December 18, 2009 1 Harvard University, School of Engineering and Applied Sciences, 20 Oxford Street, Cambridge, MA 2 Aerodyne Research Inc., Center for Atmospheric and Environmental Chemistry, 45 Manning Road, Billerica, MA

  2. Significance of HONO • HONO + hνNO + OH (τ ~ 10 to 20 mins); • NighttimeHONO buildup provides early morning kick to chemistry; • Recent observations of daytime HONO in urban, rural and remote environments suggest significance as HOx source.

  3. Motivation for instrumentation • Desire for direct spectroscopic measurement to unambiguously identify HONO; • High time resolution capable of eddy covariance flux measurements; • To be deployed at Harvard Forest to measure atmosphere-biosphere exchange of HONO and NO2 over multiple seasons.

  4. Tunable Infrared Laser Differential Absorption Spectroscopy (TILDAS)

  5. TILDAS…continued HONO laser (1660 cm-1) NO2 laser (1604 cm-1) HONO NO2 H2O

  6. Performance • Absorbance precision of less than 3×10-6 Hz-1/2 in one-second; • Sensitivity can improve indefinitely with time-averaging and frequent background subtractions; • Detection limits (S/N = 3) of 400 and 40 ppt in one second for HONO and NO2, respectively.

  7. Sampling technique • Siloxyl-coated quartz inlet with built-in critical orifice minimizes surface H2O interaction and separates out large particles; • Inlet and tubing are shielded/heated; • Injection of HONO and CH4 after week of sampling aircraft exhaust show no attenuation through inlet/tubing.

  8. Study of Houston Atmospheric Radical Precursor April-May ’09 - Houston, TX • Good agreement between different techniques; • Inter-comparison study by S. Thomas [manuscript in prep].

  9. Alternative Aviation Fuels Experiment Jan ’09 – Palmdale, CA • EI independent of fuel type, ambient conditions; • HONO EI increases with rated engine thrust, plateaus between 60 and 100%; • HONO to NOx ratio in aircraft exhaust (3 and 7%) higher than that of on-road vehicles (0.2 to 0.8%).

  10. Thank you! Aerodyne Research John Jayne, Tim Onash, Mike Timko, Zhenhong Yu, BerkKnighton, Sally Ng, Ed Fortner, Ryan McGovern, Dan Glenn, Rick Wehr Harvard University Josh McLaren, Bruce Daube, Marcos Longo, Eric Kort, VY Chow, Elaine Gottlieb AAFEX team Bruce Anderson and Andreas Beyersdorf SHARP team Barry Lefer, Bernhard Rappenglueck, James Flynn, Bill Brune, XinrongRen, Winston Luke, Jack Dibb, Jochen Stutz Funding agencies NSF FAA, NASA (AAFEX) Houston Advanced Research Center (SHARP) Transportation Research Board (ACRP Graduate Research Fellowship)

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