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