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

ISSAOS 2008

l‘Aquila, September 2008

Aerosol Mass Spectrometry:

The Aerosol mass Spectrometer

Hugh CoeSchool of Earth, Atmospheric and Environmental Sciences

University of ManchesterReading:

• 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

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.

QuadrupoleMass Spectrometer

Thermal Vaporization

&Electron Impact

Ionization

Aerodynamic Lens

(2 Torr)

Chopper

Turbo Pump

Turbo Pump

Turbo Pump

TOF Region

Particle Beam Generation

Aerodynamic Sizing Particle Composition

Aerodyne Aerosol Mass Spectrometer (AMS)http://cires.colorado.edu/jimenez/ams-papers.html

AMS Detection Process

Oven

e-

Electron EmittingFilament

R+

Focused Particle Beam

FlashVaporizationof Volatiles

and Semi-Volatiles

500 C

Electron Impact Ionization

Universal and quantitative chemical analysis: 0.1g/m3 sensitivity.Vaporization and analysis of most aerosol chemical constituents - with primary exception of crustal oxides and elemental carbon.

Separation of Vaporization/Ionization allows for Quantitative Measurements

AtomiserAMS

DMA

CPC

Polydisperse Aerosol Monodisperse Aerosol

SheathAir

Dry, Compressed Air

AtomiserAMS

DMA

CPC

Polydisperse Aerosol Monodisperse Aerosol

SheathAir

Dry, Compressed Air

Calibration & Experimental Set up…

IN

MW

QIEC

A

11

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

General Formula..

Nitrate Mass loading..

30,46f

fA

NO

NONO I

N

MW

QIEC 3

3

3

11

IE Ionisation Efficiency NA Avogadro’s numberQ flow rate I ion rateMW molecular weight C mass concentration

Electron Impact a well defined ionisation

3

3

NO

NOs

s

s

MW

IERIE

MW

IE

Quantification of Aerosol Mass…

So the Mass loading of component s is..

i

isA

NO

NOss I

N

MW

QIERIEC ,

3

3

111

IE Ionisation Efficiency NA Avogadro’s numberQ flow rate I ion rateMW molecular weight C mass concentrationRIE 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………

101

102

103

104

105

106

Det

ecte

d I

on

s

2902702502302101901701501301109070503010m/z

Organics NitrateSulphateAmmonium Chloride Water Air

Ambient Mass Spectrum taken in an urban site in Vancouverduring the Pacific 2001 field study.

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 217Characterization of urban and regional organic aerosols in the lower Fraser Valley using two Aerodyne Aerosol Mass Spectrometers. Atmos Environ 38:5745–5758.

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.

QuadrupoleMass Spectrometer

Thermal Vaporization

&Electron Impact

Ionization

Aerodynamic Lens

(2 Torr)

Chopper

Turbo Pump

Turbo Pump

Turbo Pump

TOF Region

Particle Beam Generation

Aerodynamic Sizing Particle Composition

Aerodyne Aerosol Mass Spectrometer (AMS)http://cires.colorado.edu/jimenez/ams-papers.html

Particle Velocity Calibration

6

7

8

9100

2

3

Vel

ocity

(m s

-1)

4 5 6 7100

2 3 4 5 6 71000

2

Aerodynamic Diameter (nm)

NH4NO3 DOP PSL Fluent Fit to Data

Predicted and Measured Particle

Collection Efficiency

Aerodynamic Particle Focusing

1.0

0.8

0.6

0.4

0.2

AM

S C

olle

ctio

n E

ffic

ien

cy10

12 4 6 8

102

2 4 6 8

103

2 4 6 8

104

Aerodynamic Diameter (nm)

FLUENT Simulation Data

Example of AMS Output

Organics

Sulphate

Nitrate

Ammonium

Organics

Sulphate

Nitrate

Ammonium

Example of AMS Output

Organics

Sulphate

Nitrate

Ammonium

Example of AMS Output

Collection Efficiency (CE)

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

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.

Quantification of Aerosol Mass…

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

i

isA

NO

NOss I

N

MW

QIERIECEC ,

3

3

1111

IE Ionisation Efficiency NA Avogadro’s numberQ flow rate I ion rateMW molecular weight C mass concentrationRIE relative IE CE 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)

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

Mexico CityApril 9, 2003

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

Evidence for OOA being a Secondary Photochemical Product

Much higher SOA than predicted with current modelsDiscrepancy appears to increase with time

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

DeGouw et al.Heald et al.

Johnsonet al.

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

A Compact Time of Flight AMS

-0.2

0.0

0.2

3:30 PM5/25/2005

3:45 PM 4:00 PM 4:15 PM 4:30 PM 4:45 PM

2

1

0

-1

-2

11:4519/07/2004

12:00 12:15 12:30

Nitrate Sulphate Organics

Ma

ss C

once

ntr

atio

n (

µg

m-3

)

FAAM quadrupole

Caltech TOF

-0.2

0.0

0.2

3:30 PM5/25/2005

3:45 PM 4:00 PM 4:15 PM 4:30 PM 4:45 PM

2

1

0

-1

-2

11:4519/07/2004

12:00 12:15 12:30

Nitrate Sulphate Organics

-0.2

0.0

0.2

3:30 PM5/25/2005

3:45 PM 4:00 PM 4:15 PM 4:30 PM 4:45 PM

-0.2

0.0

0.2

3:30 PM5/25/2005

3:45 PM 4:00 PM 4:15 PM 4:30 PM 4:45 PM

2

1

0

-1

-2

11:4519/07/2004

12:00 12:15 12:30

Nitrate Sulphate Organics

Ma

ss C

once

ntr

atio

n (

µg

m-3

)

FAAM quadrupole

Caltech TOF

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

SP2-AMS schematicSomething for the future……

Oil Lamp Soot Particles

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

70x103

60

50

40

30

20

10

0

Sig

nal

10080604020

m/z

C8

m/z=96

C7

m/z=84

Air Beam Organics Elemental Carbon

C6

m/z=72

C5

m/z=60

C3

m/z=36

C4

m/z=48

C2

m/z=24

C1

m/z=12

H2Om/z=18

N2

m/z=28