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ISSAOS 2008 l‘Aquila, September 2008 Aerosol Mass Spectrometry: The Aerosol mass Spectrometer PowerPoint PPT Presentation


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ISSAOS 2008 l‘Aquila, September 2008 Aerosol Mass Spectrometry: The Aerosol mass Spectrometer Hugh Coe School of Earth, Atmospheric and Environmental Sciences University of Manchester. Reading:

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ISSAOS 2008 l‘Aquila, September 2008 Aerosol Mass Spectrometry: The Aerosol mass Spectrometer

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ISSAOS 2008

l‘Aquila, September 2008

Aerosol Mass Spectrometry:

The Aerosol mass Spectrometer

Hugh Coe

School of Earth, Atmospheric and Environmental Sciences

University of Manchester

Reading:

  • D Murphy, The design of single particle laser mass spectrometers, in: Mass Spectrometry Reviews, 2007, 26, 150-165.

  • M. R. Canagaratna et al., Chemical and microphysical characterisation of ambient aerosols with the Aerodyne Aerosol Mass Spectrometer in: Mass Spectrometry Reviews, 2007, 26, 185-222.

  • H. Coe and J. D. Allan, “Aerosol Mass Spectrometry” in “Atmospheric techniques” ed D. E. Heard, Blackwell Scientific Publishing, 2006

  • http://cires.colorado.edu/jimenez/ams-papers.html


Aerodyne Aerosol Mass Spectrometer (AMS)

http://cires.colorado.edu/jimenez/ams-papers.html

Particle

Particle Beam

Aerodynamic Sizing

Composition

Generation

Quadrupole

Mass Spectrometer

Chopper

Thermal Vaporization &

Electron Impact Ionization

TOF Region

Aerodynamic Lens

(2 Torr)

Turbo Pump

Turbo Pump

Turbo Pump

Particle Inlet (1 atm)

100% transmission (30-600 nm), aerodynamic sizing, linear mass signal.

Development of an Aerosol Mass Spectrometer for Size and Composition Analysis of Sub-micron Particles. Jayne et al., Aerosol Science and Technology 33:1-2(49-70), 2000.


Flash

Vaporization

of Volatiles

and Semi-Volatiles

Electron Emitting

Filament

Focused

Particle Beam

e-

Oven

500 C

R+

Electron Impact Ionization

AMS Detection Process

Separation of Vaporization/Ionization allows for Quantitative Measurements

Universal and quantitative chemical analysis: 0.1mg/m3 sensitivity.

Vaporization and analysis of most aerosol chemical constituents

- with primary exception of crustal oxides and elemental carbon.


Calibration & Experimental Set up…


Quantification of Aerosol Mass…(Jimenez et al., 2003)

General Formula..

Nitrate Mass loading..

IE Ionisation EfficiencyNA Avogadro’s number

Q flow rateI ion rate

MW molecular weightC mass concentration


Electron Impact a well defined ionisation


Quantification of Aerosol Mass…

So the Mass loading of component s is..

IE Ionisation EfficiencyNA Avogadro’s number

Q flow rateI ion rate

MW molecular weightC mass concentration

RIE relative ionisation efficiency


Quantification of Aerosol Mass…

Allan JD, Delia AE, Coe H, Bower KN, Alfarra MR, Jimenez JL, Middlebrook AM, Drewnick F, Onasch TB, Canagaratna MR, Jayne JT, Worsnop DR. 2004b. A generalised method for the extraction of chemically resolved mass spectra from Aerodyne aerosol mass spectrometer data. J Aerosol Sci 35:909–922, doi:910.1016/j.jaerosci.

2004.1002.1007.


This is what we measure………

Alfarra MR, Coe H, Allan JD, Bower KN, Boudries H, Canagaratna MR, Jimenez JL, Jayne JT, Garforth A, Li S-M, Worsnop DR. 2004.

CHARACTERIZATION OF AMBIENT AEROSOLS WITH AN AEROSOL MASS SPECTROMETER &

Mass Spectrometry Reviews DOI 10.1002/mas 217

Characterization of urban and regional organic aerosols in the lower Fraser Valley using two Aerodyne Aerosol Mass Spectrometers. Atmos Environ 38:5745–5758.


Aerodyne Aerosol Mass Spectrometer (AMS)

http://cires.colorado.edu/jimenez/ams-papers.html

Particle

Particle Beam

Aerodynamic Sizing

Composition

Generation

Quadrupole

Mass Spectrometer

Chopper

Thermal Vaporization &

Electron Impact Ionization

TOF Region

Aerodynamic Lens

(2 Torr)

Turbo Pump

Turbo Pump

Turbo Pump

Particle Inlet (1 atm)

100% transmission (30-600 nm), aerodynamic sizing, linear mass signal.

Development of an Aerosol Mass Spectrometer for Size and Composition Analysis of Sub-micron Particles. Jayne et al., Aerosol Science and Technology 33:1-2(49-70), 2000.


Aerodynamic Particle Focusing

Predicted and Measured Particle Collection Efficiency

Particle Velocity Calibration


Example of AMS Output

Organics

Sulphate

Nitrate

Ammonium


Example of AMS Output

Organics

Sulphate

Nitrate

Ammonium


Example of AMS Output

Organics

Sulphate

Nitrate

Ammonium


Collection Efficiency (CE)

Matthew, B.M., T.B. Onasch, and A.M. Middlebrook. Collection Efficiencies in an Aerodyne Aerosol Mass Spectrometer as a Function of Particle Phase for Laboratory Generated Aerosols. Aerosol Science and Technology, In press, July 2008.

Takegawa, N., Y. Miyazaki, Y. Kondo, Y. Komazaki, T. Miyakawa, J.L. Jimenez, J.T. Jayne, D.R. Worsnop, J. Allan, and R. J. Weber (2005), Characterization of an Aerodyne Aerosol Mass Spectrometer (AMS): Intercomparison with other Aerosol Instruments, Aerosol Science and Technology, 39, 760-770, 2005


Quantification of Aerosol Mass…

Including the CE, the Mass loading of component s is..

IE Ionisation EfficiencyNA Avogadro’s number

Q flow rateI ion rate

MW molecular weightC mass concentration

RIE relative IECE collection efficiency


Understanding Organic Aerosols – Zhang et al., 2005


Understanding Organic Aerosols – Zhang et al., 2005


Understanding Organic Aerosols – Zhang et al., 2005

A factor analysis of the time series of organic mass spectra……


Extended to Positive Matrix Factorisation (PMF)


Evidence for OOA being a Secondary Photochemical Product

Data from Gaffney, Marley, Brune, Volkamer, Cardenas et al.

Mexico City

April 9, 2003

Volkamer, Jimenez, et al., GRL, 2006.


Increase in SOA with residence time in atmosphere – observations much greater than models

DeGouw et al.

Johnson

et al.

Heald et al.

Volkamer, Jimenez, et al., GRL, 2006.

  • Much higher SOA than predicted with current models

    • Discrepancy appears to increase with time


A Compact Time of Flight AMS

Data from Shane Murphy Caltech


A High resolution time of Flight AMS


The Ability to resolve atomic composition


The Ability to resolve atomic composition


Ambient aerosol is much more oxygenated than chamber aerosol


Something for the future……

SP2-AMS schematic


Oil Lamp Soot Particles

Obtain chemical information on elemental carbon clusters and organic compounds coating the soot cores


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