Development of a high mass resolution time of flight aerosol mass spectrometer

1. Development of a high mass resolution time of flight aerosol mass spectrometer P.F. DeCarlo, J. Kimmel, A. Aiken, K. Docherty, J.L. Jimenez University of Colorado A. Trimborn, J. Jayne, D.R. Worsnop Aerodyne Research Inc. M. Gonin, K. Furher, T. Horvath Tofwerk, A.G. In press in Analytical Chemistry http://cires.colorado.edu/jimenez/ams-papers.html (Paper 109)

2. Talk Outline • Instrument Schematic • Example Mass Spectra • Resolving Power • Detection Limit Comparison • Time Resolution • Aircraft, Plume Studies • Data processing • High resolution “sticks” • Example Data • Future Work

3. High Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS) MCP Reflectron Grid ToF Mass Spectrometer Signal to ADC Optional Hard Mirror (W mode) W mode Vmode Generation Pulsed Orthogonal Extraction Chopper PTOF Region Thermal Vaporization & 70 ev EI Ionization Aerodynamic Lens (2 Torr) Turbo Pump Turbo Pump Turbo Pump Particle Inlet (1 atm)

4. Sample PFK spectra for V and W modes 1000 mg/m3 atomized PFK in 2-propanol

5. Res. Power 3400 Res. Power 1200 CHNO C2H3O C3H7 Benefits of High Resolution

6. AMS Spectra comparison

7. Res. Power 3400 Res. Power 1200 CHNO C2H3O C3H7 Resolving Power = m / Dm

8. Instrument Detection Limits • 1-minute averages of HEPA filtered air. • 3 * std. dev. of species mass concentration

9. Fast time resolution • Preliminary MIRAGE data (March 2006) • V-mode data • 12 second data high correlation light scattering (Univ. of Hawaii)

10. Custom algorithm to integrate ion signals Modified Gaussian Peak Shape Data Processing (m/z 81)

11. Size Resolved Chemistry • 1 hour averages on 12x VACES aerosol concentrator (USC) • Kim et al. (2004), J. of Aerosol Sci., 32: 1281. • Unit resolution instrument would only measure black curve. • High resolution allows detailed investigation of size resolved chemistry.

12. Separation of Ion Classes • 5 minute afternoon average from SOAR-1 • Unit resolution instrument would only resolve peak height

13. Future and Ongoing work • Utilize the richness of the chemical information from the HR-ToF-AMS • Field Studies (e.g. as input PMF) • Laboratory work (e.g. O/C ratios) • New Instrument development • MS/MS capability • Collisional cooling for more sensitivity and higher resolution • Soft-ionization strategies

14. Acknowledgements • A. Clarke, J. Zhou, Y. Shinozuka, and S. Howell from the University of Hawaii for the use of their Nephelometer data. • C. Sioutas, P. Fine, M. Geller, and S. Sardar (USC) for use of VACES concentrator • M. Northway, P. Ziemann • Funding Sources • NSF CAREER ATM-0449815, NASA NNG04GA67G, and NSF/UCAR S05-39607 • Grants EPA RD-83216101-0 and NSF ATM-0513116 • EPA Star – Graduate Research Fellowship • Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not reflect the views of the funding agencies. • Rest of the Jimenez Group

15. Questions?

16. Modified Gaussian Peak Shape

17. Particle Sampling Statistics