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Urban Ammonia Source Characterization Using Infrared Quantum Cascade Laser Spectroscopy

AERODYNE RESEARCH, Inc. Urban Ammonia Source Characterization Using Infrared Quantum Cascade Laser Spectroscopy. Mark S. Zahniser. NADP Ammonia Workshop October 2003. NH 3 DETECTION WITH INFRARED SPECTROSCOPY. Strong infrared absorber  high sensitivity

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Urban Ammonia Source Characterization Using Infrared Quantum Cascade Laser Spectroscopy

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  1. AERODYNE RESEARCH, Inc. Urban Ammonia Source Characterization Using Infrared Quantum Cascade Laser Spectroscopy Mark S. Zahniser NADP Ammonia Workshop October 2003

  2. NH3 DETECTION WITHINFRARED SPECTROSCOPY • Strong infrared absorber  high sensitivity • Distinct absorption lines  high selectivity • Known molecular properties  absolute concentrations without calibration standards Beer’s Law: A = N s l • Methods: • Fourier Transform Infrared (FTIR) • Photoacoustic detection with CO2 laser (PA) • Tunable Infrared Laser Absorption (TILDAS) • Near-IR • Mid-IR • Lead-salt diode lasers (cryogenic cooling) • Quantum Cascade Lasers (new- TE cooling)

  3. Cryogen-Free Pulsed QC Lasers ADVANTAGES: • Decreased Instrument Size and Weight • Improved Laser Mode Stability • Unattended Remote Monitoring • “Turn-Key” Operation DISADVANTAGES: • Narrow Wavelength Tuning • Increased Laser Line Width

  4. Compact QC Laser Spectrometer • 56 m cell • 0.1 s response time • TE or LN2 Detectors • 19 inch rack mount • MULTIPLE GASES • NH3-C2H4 (967 cm-1) • CO2-N2O (2240 cm-1) • CH4-N2O-H2O(1270 cm-1)

  5. NH3 at Iowa Swine Farm • Automated single QC laser instrument at 966 cm-1 • Continuous operation for 4 weeks during ETV program • Enormous ammonia signals! • 10 Hz data rate suitable for eddy correlation

  6. AMMONIA DETECTION WITH QCL Path Length 210 m Line Width 0.006 cm-1 (180 MHz) PRECISION 55 ppt Hz-1/2 3x10-5 absorbance

  7. U. Manchester Inst. Technol. QC-TILDAS NH3 - NO - NO2 at Chelmsford UK Field Site August 2003

  8. Open-path FTIR in Mexico City View Michel Grutter, Edgar Flores, Roberto Basaldud Centro de Ciencias de la Atmósfera Universidad Nacional Autónoma de México (UNAM)

  9. Set Up sample Compounds: NH3, O3, CO, NO, N2O, CO2, CH4, HCHO references OPEN PATH FTIR SPECTROMETER (Grutter et al.) 100 – 500 m spectrometer detector

  10. NH3 FTIR SPECTRUM in MEXICO CITY (Grutter et al.) Sun Apr 06 05:25:08 2003 92.9 ppb NH3 100 ppb 100 50 0 NH3 Mixing Ratios (ppb)

  11. Mexico City NH3 FTIR Data DIURNAL CYCLE APRIL 2003 CO2 CORRELATION 0.9 mmol NH3/mol CO2

  12. MEXICO CITY AIR POLLUTION STUDY, APRIL 2003 FRONT INLET REAR INLET QCL (NH3) Dual TDL (NO2, HCHO)

  13. AMMONIA INLET DESIGN

  14. General Traffic & Market Area Mexico City, 2003

  15. Mexico City Automobile Traffic

  16. BOSTON TUNNEL NH3

  17. BOSTON HIGHWAY NH3 FREEWAY OVER-PASS

  18. QUAD-QC OPEN PATH TILDAS • Four QC Lasers with time-multiplexing • NO, NO2, N2O, NH3,CO • CO2 reference • Cross-road retro- reflector • Range 200 meters

  19. AUTOMOBILE EXHAUST PLUME SPECTRA LASER 1 2240 cm-1 LASER 2 967 cm-1 LASER 3 1906 cm-1 NO N2O NH3 CO2 0.02 s

  20. Automobile exhaust plume

  21. CATALYTIC CONVERTER WARM-UP NO NH3 REPEATED PASSES OF SAME AUTOMOBILE 0 - 5 minutes after cold start NO emissions decrease NH3 emissions increase

  22. CATALYST WARM-UP NO N2O  (N2)  NH3

  23. CONCLUSIONS • QC LASER METHOD FOR NH3 • OPEN PATH • EXTRACTIVE SAMPLING • MOBILE “MAPPING” FOR SOURCE IDENTIFICATION AND QUANTIFICATION • AUTOMOBILE EXHAUST IS SIGNIFICANT SOURCE OF URBAN AMMONIA FROM CATALYTIC REDUCTION OF NO

  24. Aerodyne Colleagues Joanne Shorter Scott Herndon David Nelson Barry McManus Quan Shi Patrick Kirwin Jeff Mulholland Chuck Kolb UNAM (FTIR) Michel Grutter M.I.T Ed Dunlea Luisa Molina Mario Molina Alpes Lasers Antoine Meuller Yargo Bonnetti U. Manchester Inst. Tech. Martin Gallagher Keith Bower Jamie Whitehead Danish Inst. Agriculture Sci Willem Asman Anton Thomsen Kirsten Schelde Acknowledgments • US EPA, NSF, NASA, DOE, NIST Small Business Innovation Research Programs

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