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Suresh Regmi Literature Seminar Presentation CHEM 7800 November 9, 2009

Single Aerosol Particle Analysis Using Aircraft Compatible Time-of-Flight Mass Spectrometers in Real Time (A-ATOFMS & SPLAT II). Suresh Regmi Literature Seminar Presentation CHEM 7800 November 9, 2009. Objective.

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Suresh Regmi Literature Seminar Presentation CHEM 7800 November 9, 2009

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  1. Single Aerosol Particle Analysis Using Aircraft Compatible Time-of-Flight Mass Spectrometers in Real Time(A-ATOFMS & SPLAT II) Suresh Regmi Literature Seminar Presentation CHEM 7800 November 9, 2009

  2. Objective To compare and contrast two TOF instruments ( A-ATOFMS & SPLAT II) developed for real time detection and analysis of single aerosol particles.

  3. Articles Development and characterization of an aircraft aerosol time-of-flight mass spectrometer Kerri A. Pratt, Joseph E. Mayer, John C. Holecek, Ryan C. Moffet, Rene O. Sanchez, Thomas P. Rebotier, Hiroshi Furutani, Marc Gonin, Katrin Fuhrer, Yongxuan Su, Sergio Guazzotti, and Kimberly A. Prather (University of California, San Diego, California). Anal. Chem. 2009, 81, 1792–1800 SPLAT II: an aircraft compatible, ultra-sensitive, high precision instrument for in-situ characterization of the size and composition of fine and ultrafine particles AllaZelenyuk ; Juan Yang ; Eric Choi ; Dan Imre (Pacific Northwest National Laboratory, Richland, Washington). Aerosol Sci. Technol. 2009, 43, 411–424,

  4. Human health • air quality, airborne pathogen transport • Energy balance of earth • aerosol optical properties • direct/indirect effects • Cloud nucleation • Geochemical cycles • metals, nutrients, organics • Acidification (sulfur, nitrogen) Why Study Aerosol? http://www.ucar.edu/learn/1_1_1.htm

  5. Why Single Aerosol Particles in Real Time? Particle size is critical for health effects Chemical composition of a particle and mixed composition particles Individual particle size and composition represents its source. Prevents sampling artifacts / secondary pollutant formation during detection Real picture of the air you breathe

  6. Research Challenges Requires faster data acquisition speeds to provide high spatial resolution No sample collection (advantages and disadvantages) Difference in shape of the particles Enormous variety, complexity, and fragility of particles

  7. Why Aircraft Based Study ? Direct and indirect radiative forcing depend on aerosol vertical and horizontal profiles. Quantify the properties of particles as a function of altitude Horizontal distribution of particles, aircraft route selection Role of particles in cloud nucleation (Aerosol – cloud interaction) Low aerosol concentration High aerosol concentration http://earthobservatory.nasa.gov/Features/Aerosols/

  8. Requirements for Aircraft Based Instrument Size of the instrument Weight of the instrument Vibration shielding Data acquisition

  9. Real Time -Single Aerosol Time of Flight Mass Spectrometer

  10. Time of Flight Mass Spectrometer Ionization chamber Laser Flight tube Reflectron Detector

  11. Aircraft-Aerosol Time of Flight Mass Spectrometer (A-ATOFMS) Principal investigator: Dr. Kimberly Prather

  12. A-ATOFMS in Working Condition

  13. A-ATOFMS : On Board Power consumption- 1.4 kW

  14. A-ATOFMS : Inside 7 × 10 -7Torr

  15. Aerosol particle Po 210 neutralizer Particle Sizing Aerodynamic lens Skimmers Laser PMT

  16. Ionization: Laser Desorption - - + + + - + + + + - + + - - - + + Extractors 266 nm Nd:YAG DI laser

  17. A-ATOFMS : Separation and Detection

  18. A-ATOFMS

  19. Mass Spectra : Organic Carbon - Sulfate - Nitrate

  20. Mass Spectra : Dust - Sulfate - Nitrate

  21. Particle Concentration )

  22. Conclusions Transportable and high data acquisition capability Real time source apportionment software Use of neutralizer Duel polarity mass analyzer Field tested in ground and on board

  23. Single Particle Laser Ablation Time of Flight Mass Spectrometer II (SPLAT II)Principal investigatorDr. AllaZelenyuk

  24. Real Time -Single Aerosol Time of Flight Mass Spectrometer

  25. SPLAT II : Ready to Fly

  26. 2.25 × 10-6Torr SPLAT II : Inside • Power consumption • 3.5 kW • Total wt – 400 kg • Dimension - 143 × 69.6 • × 124.5 cm

  27. Particle Sizing Spot 330 µm 532 nm, 300 mw 532 nm, 300 mw Zelenyuk et al. Aerosol Sci. Technol. 2009_2

  28. Ionization: Evaporation + Laser Ablation • Requires lower laser intensity • Less fragmentation • Flexibility for optimization 193 nm UV excimer laser, 8 ns pulse, 0.5-2 mJ/pulse, Focal spot- 550 × 750 µm UV laser + + + + + + IR laser 10.6 µm CO2 laser, 50 ns pulse, 110 mJ/pulse, spot -1 mm IR/UV ionization

  29. Mass Spectrum : SPLAT II Vs. NIST Trans-sobrerol 170 Lab OC-Nitrate-Sulfate 70 ev EI ionization Trans-sobrerol 170

  30. Mass Spectrum : IR/UV Vs. UV 334 nm DOP- 390.56 Lab OC-Nitrate-Sulfate DOP - 390.56

  31. Mass Spectra: Convair 580 Aircraft Dust particle Biomass burning particle

  32. Conclusion Transportable Can size over 500 particles and record up to 100 individual particles mass spectra per second Real time source apportionment software Can differentiate between spherical and aspherical particles Two step ionization process Field tested in ground and on board

  33. Summary/ Evaluation Both papers summarize an important scientific investigation Devoted in the development of instruments for real time detection and analysis of single aerosol particles Improved version of their predecessor Field as well as on board tested Ionization - major difference

  34. A-ATOFMS Vs. SPLAT II

  35. Instrumentation

  36. Ionization • UV • Hard ionization • Irreproducible mass spectra • Easier optics alignment • Non-linear, multiphoton • process • Matrix and charge transfer • effects • IR/UV • Soft /user controlled ionization • Reproducible mass spectra/ • Independent of UV laser fluence • Difficult optics alignment • Linear relationships between the • integrated mass spectral • intensities and particle mass • Less influence by matrix and • charge transfer

  37. Dual Polarity Vs. Single Polarity TOF Single polarity Dual polarity ? http://www.internetvibes.net/gallery/disney-pixar-cars-images-from-the-cartoon/

  38. Evaluation - Suggestion Comparison with their own instrument Competition to show the instrument portable Stocked with TOF Why not Ion trap?

  39. Alternative to Time of Flight MS: Ion Trap MS Simpson et al. International Journal of Mass Spectrometry 281 (2009) 140–149

  40. Conclusions Online analysis of single particle size, chemical composition, density, and optical properties A-ATOFMS- more sensitive for detection limit and dynamic range SPLAT II- Reproducible mass spectra, accurate chemical composition, differentiate spherical and aspherical particles Ion trap instead of flight tube – smaller, and lighter instrument

  41. Acknowledgement Dr. Gilman Dr. McCarley Dr. Murray Dr. Gilman’s research group Audience

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