ams introduction doug worsnop ams users meeting...

1

AMS Introduction

Doug Worsnop

AMS Users Meeting

Caltech

Georgia Tech

FZ - Juelich

October 24, 2003

October 8, 2004

25 August, 2005

CE Issues – “magic” “fudge factor” ~ 0.5 +/− 0.1

NY, Tokyo, Ron Brown 2004, Chebogue Point

Aircraft: DoE G-1, Env Can King Air, BA146, ONR Twin Otter, NOAA P3

Beam width probe

ambient, soot (Boston College), ozonolysis of oleic acid (Harvard)

Lens transmission – standard, high throughput and high pressures lenses

Light Scattering Probe:

FIRST Direct Measurement of Bounce Eben Cross, Tim Onasch

HOA / OOA – Qi Zhangseparation of “primary” and “secondary” OMdirect estimate of OC content

Tof-AMS – C, V and W Frank Drewnick, Silke Hings, Peter Decarlo

Soft Ionization – VUV, Li+, neg ions Megan Northway, Achim Trimborn

Frag waves - updated diagnostics; SO4/SO3, MSA, orgainc/SO4 interference

2

Aerosols in the Atmosphere

C.E. Kolb, Nature, 2002

Number Density

Surface Area

Mass “Remote Continental”Pandis and Seinfeld, 1998

Ultrafine Fine Coarse

Ambient Aerosol Size Distribution

Goal: Size-Resolved Chemical Composition of Ambient Aerosol

EPA, 1999

3

Number Density

Surface Area

Mass “Remote Continental”Pandis and Seinfeld, 1998

Ultrafine Fine Coarse

Ambient Aerosol Size Distribution

Goal: Size-Resolved Chemical Composition of Ambient Aerosol

EPA, 1999

EPA limits on Aerosol Mass Loading:

Annual: PM2.5 < 15 µg/m3

Daily: < 65

Clean PM2.5= 4 µg m-3

Aerosol Impact on VisibilityUSX Tower

PollutedPM2.5= 45 µg m-3USX Tower

July 2, 2001

July 18, 2001

Taken from same location, same time of day in Pittsburgh(at PAQS main site)

4

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

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

Aerosol Mass Spectrometer (AMS)

• Efficient transmission (40-1000 nm), aerodynamic sizing, linear mass signal

• Non-refractory PM1.0 mass loadings and chemically-speciated mass distributions

Particle Inlet (1 atm)

AMS Particle Detection Process

Universal and quantitative chemical analysis: 0.01µg/m3 sensitivity.Vaporization and analysis of most aerosol chemical constituents

- with primary exception of crustal oxides and elemental carbon.

Positive IonMass

Spectrometry

Vaporizer

e-

Electron EmittingFilament

R+

Focused Particle Beam

FlashVaporization

of Non-RefractoryComponents (NR)

600 C Electron Impact Ionization

5

Operating Modes: Alternate between two modes

Size

Dis

trib

utio

n • Beam Chopped• Spectrometer is fixed (subset of 0-300 amu)

• Beam Open• Spectrometer is scanned (0-300 amu)

Mass Loadings20

15

10

5

0

Mas

s C

once

ntra

tion

(µg

m-3

)12:00 PM4/15/2003

1:00 PM 2:00 PM 3:00 PM 4:00 PM

Date and Time

Ammonium Sulphate Nitrate Organics

14

12

10

8

6

4

2

0

dM/d

logD

va (µ

g m

-3)

2 3 4 5 6 7 8 9100

2 3 4 5 6 7 8 91000

2

Vacuum Aerodynamic Diameter (nm)

Ammonium Nitrate Sulphate Organics

Ion

Sig

nal

0.0060.0040.0020.000Particle TOF (s)

(limited comp. info)

0.001

0.01

0.1

1

10

100

Nitr

ate

Equ

ival

ent M

ass

Con

cent

ratio

n (µ

g m

-3)

120110100908070605040302010m/z

Species

Air 188Water -0.0591Ammonium 1.02Nitrate 1.24Sulphate 1.81Chloride 0.0413PAH 0.00169Organics 7.93Others 0.883

(no size info)

Ave

rage

Com

posi

tion

Mass Distributions

3.0

2.5

2.0

1.5

1.0

0.5

0.0

Nitr

ate

Equi

vale

nt M

ass

Con

cent

ratio

n (µ

g m

-3)

1412010080604020m/z (Daltons)

Ammonium 4.8 ug/m3Nitrate 5.8Sulphate 9.4Organics 13.4Chloride 0.15

Mexico City 2/2002

43 44

57

Urban organic aerosol is a mixture of hydrocarbon and oxygenated components

6

MS Signatures for Aerosol Species Identificationcolor coded to match spectra

Water H2O H2O+ , HO+ , O+ 18, 17, 16Ammonium NH3 NH3+, NH2+, NH+ 17, 16, 15Nitrate HNO3 HNO3+, NO2+, NO+ 63, 46, 30

Sulfate H2SO4 H2SO4+, HSO3+, SO3+ 98, 81, 80SO2+, SO+ 64, 48

Organic CnHmOy H2O+, CO+, CO2+ 18, 28, 44(Oxygenated) H3C2O+, HCO2+, Cn’Hm+ 43, 45, ...

Organic CnHm Cn’Hm’+ 27,29,41,43,55,57,69,71...(hydrocarbon)

Group Molecule/Species Ion Fragments Mass Fragments

e-e-

e-

e-

e-

e-

Standard electron impact ionization @ 70 eVEasy to quantify: ca. NIST MS libraryEasy to separate inorganic and organic componentsSpeciation of organic composition is challenging

ELECTRON IMPACT (EI) IONIZATION

Measure all ions:

Ion Rate = Σ Ri+

independent of parent or fragment (neutral or ion)molecular mass

EI Cross Section (σ) ∝ electrons/molecule ∝ mass/molecule

Ion Rate = 2ndary electrons/sec ∝ σ • molecules/sec

Ion Rate = Σ Ri+ ∝ total mass/sec

σR + e- → R+ + e- + e-

↓Ri

+ + Rj

7

Mass Loading A ∝ (MWA/IEA) ∑ Ion Signal

EI Ionization: A + e- ----> A+ ----> ai+

Calibration Factor * (MWNO3/IENO3)

EI Ionization Cross Sections

6

4

2

0

Nitr

ate

Equi

vale

nt C

ross

Sec

tion

200150100500

Molecular Mass

Oxygenated Organics = 1.5 X NITRATE

Diesel Fuel

NitrateSulfate

Inorganics NITRATE = 1.0

Chloride

AMS Particle Detection

Universal / quantitative chemical analysis: 0.01µg/m3 sensitivity.

“EVERTYHING AT THE SAME TIME” No Separation - bulk analysis

[ no dust (oxides) or elemental (black) carbon ]

Positive IonMass

Spectrometry

Vaporizer

e-

Electron EmittingFilament

R+

Focused Particle Beam

FlashVaporization

of Non-RefractoryComponents (NR)

600 C Electron Impact Ionization

8

Aerosol Composition

• Organic aerosols are composed of thousands of compounds.

• Chemical analysis of organics is a significant challenge.

• Compound specific study can only explain a small fraction of total organic mass. Large fraction unidentified.

Figure 3.10. Speciation results for organic aerosol in Southern California (Rogge et al., 1993). Even if a hundred or so individual organic compounds were identified and quantified they represented only 15 percent or so of the total organic mass.

2003 NARSTO Assessment

CE Issues – “magic” “fudge factor” ~ 0.5 +/− 0.1

NY, Tokyo, Ron Brown 2004, Chebogue Point

Aircraft: DoE G-1, Env Can King Air, BA146, ONR Twin Otter, NOAA P3

Beam width probe

ambient, soot (Boston College), ozonolysis of oleic acid (Harvard)

Lens transmission – standard, high throughput and high pressures lenses

Light Scattering Probe:

FIRST Direct Measurement of Bounce Eben Cross, Tim Onasch

HOA / OOA – Qi Zhangseparation of “primary” and “secondary” OMdirect estimate of OC content

Tof-AMS – C, V and W Frank Drewnick, Silke Hings, Peter Decarlo

Soft Ionization – VUV, Li+, neg ions Megan Northway, Achim Trimborn

Frag waves - updated diagnostics; SO4/SO3, MSA, orgainc/SO4 interference

9

Observed ‘Traffic’ Mode in Size Distributions

Scotland SASUA-3

Remote Site Mono-modal Aged-Transported

Urban Site Bi-modalLocal Sources

ACE ASIA

Allan, Alfarra et al. (U. Manchester)

5 6 7 8 9100

2 3 4 5 6 7 8 91000

2 3

3

2

1

04 5 6 7 8 9

1002 3 4 5 6 7 8 9

10002 3 5 6 7 8 9

1002 3 4 5 6 7 8 9

10002 35 6 7 8 9

1002 3 4 5 6 7 8 9

10002 35 6 7 8 9

1002 3 4 5 6 7 8 9

10002 3

SulfateOrganicsNitrate

Cheju-Do Island, KoreaApril, 2001

3

2

1

04 5 6 7 8 9

1002 3 4 5 6 7 8 9

10002 3

3

2

1

04 5 6 7 8 9

1002 3 4 5 6 7 8 9

10002 3

3

2

1

04 5 6 7 8 9

1002 3 4 5 6 7 8 9

10002 3

3

2

1

04 5 6 7 8 9

1002 3 4 5 6 7 8 9

10002 3

Aerodynamic Diameter (nm)

OrganicsNitrateSulfate

Edinburgh, ScotlandNovember, 2000

dM/d

logD

(µg

m-3

)

Aerodynamic Diameter (nm)Accumulation modeAccumulation mode‘Traffic’ mode

NO3= SO4= NH4+ nss-Cl-

OM vs OC

Takegawa et al., 2005Assumed CE = 0.5

OM CnHmOp⎯⎯ = ⎯⎯⎯⎯OC Cn

10

46

45

44

43

42

41

40

Latit

ude

-74 -72 -70 -68 -66

Longitude

Boston

New York City

Ronald H. BrownNEAQS 2004Cruise Track

outflow

ICARTT – International Consortium for Atmospheric Resaerchon Transport and Transformation

Onasch, Quinn, Bates et al

AMS (NR-PM1) quantification

25

20

15

10

5

0

AMS

SO

4

2520151050PILS SO4

5

4

3

2

1

0

AMS

NH

4

543210PILS NH4

14

12

10

8

6

4

2

0

AMS

Org

6420OCEC

35

30

25

20

15

10

5

0

AMS

tota

l

35302520151050DMPS mass

Slope = 1.0R2 = 0.92

Slope = 1.94R2 = 0.71

Slope = 1.16R2 = 0.87

Slope = 0.87R2 = 0.81

1:1 line

1:1 line

1:1 line

2:1 line

• Composition/phase-dependent collection efficiency (CE) applied• Correction for smaller cut diameter in AMS lens compared to PM1 impactors

11

1.0

0.8

0.6

0.4

0.2

0.0

CE

3.02.52.01.51.00.50.0

NH4/SO4 Ratio

0.4

0.3

0.2

0.1

0.0

AM

S W

ater Mass Fraction

Apparent CE depends on NH4/SO4 ratio

14

12

10

8

6

4

2

0

AMS

SO

4=

14121086420Impactor nss SO4=

12

10

8

6

4

2

0

ug/m

3

220210200190

DOY

y = 1.2x - 0.52, r^2 = 0.86

Impactor nssSO4 AMS SO4

ICARTT Chebogue Point AMS - Impactor Comparison

AMS SO4 vs Impactor nssSO4 (Quinn, NOAA PMEL)

CE = 0.5

12

PMTACS-NY 2004 Weimer, Drewnick, Demerjian et al

CE = 0.42

4) Measurements of Particulate Water with the AMS

• Using Brendan’s CE data, we looked at the water mass fraction/total mass (water plus dry mass) as f(RH) for both ammonium sulfate and ammonium nitrate particles

• For both particle compositions, the gas phase water was subtracted from the difference signal as a f(RH) before the particulate water was derived.

13

Gas phase water calibration

• Measure RH and Temperature (water vapor pressure)

•Subtract gas phase water contribution using water vapor pressure and calibration

Middlebrook, Matthews 2005

6000

4000

2000

0

dM/d

T (µ

g m

-3 s

-1)

5x10-343210Time of Flight (s)

Water

Gas phase Particle source

4) Ammonium Sulfate Water Content

-1.0

-0.5

0.0

0.5

1.0

Mw

ater

/Mto

tal

100806040200

Sampling Line Relative Humidity (%)

Ammonium Sulfate Particles hydration expts.

dehydration expts. Tang, 1980

Ddma,dry = 343 nmDdma,dry = 199 nmDdma,dry = 100 nm

14

4) Ammonium Nitrate Water Content

-1.0

-0.5

0.0

0.5

1.0M

wate

r/Mto

tal

100806040200

Sampling Line Relative Humidity (%)

Ammonium Nitrate Particles hydration expts.

dehydration expts. Tang, 1980

Ddma,dry = 343 nmDdma,dry = 199 nm

Do we have a chance to get information about xH2O – at least a lower limit ? (calculations with Pitzer + Unifac)NH4HSO4 / Glutaric Acid - mole fractions from AMS data

15

Beam Width Probe

Alex Huffman et al – detailed description in press

Dara Salcedo – analysis of Mexico City Data

also James Allan

Interesting but not critical

…. “all” ambient particles are focused on the oven

BWP analysis from Mexico City0.9

0.8

0.7

0.6

0.5

0.4

0.3

0.2

sigm

a

4/11/2003 4/16/2003 4/21/2003 4/26/2003 5/1/2003dat

sigma (pt every 34 min) 90% : 0.28 - 0.50 95% : 0.265 - 0.55 98% : 0.25 - 0.60

16

Figures from Huffman et alRed line is the fit that I used in order to calculate sigma for the BWP data

100

80

60

40

20

0

% o

f Tot

al

807060504030Wire sector (arbitrary units)

100

80

60

40

20

0

No cooling 90 % RH

QUEST (Finland) Beam Width Probe Attenuation

Allan et al

DRY (Ambient)

90% RH (Cooled)

17

0.4

0.3

0.2

0.1

0.0 ∆M

/ ∆L

ogD

aero

(µg

m-3

)

102 3 4 5 6 7 8

1002 3 4 5 6 7 8

10002

Daero (nm)

1.0

0.8

0.6

0.4

0.2

0.0

Collection E

fficiency

Queens Surface Corp.

Flame generated soot in the lab(Slowik et al, 2005; DeCarlo et al., 2005)

Diesel particles on the road

(Canagaratna et al., 2003)

What is the nature of the small mode organics?8

4

0

-4

2 3 4 5 6 7 8 9100 2 3 4 5 6 7 8 91000Vacuum Aerodynamic Diameter (nm)

2.01.00.0-1.0

dM/d

logD

va (µ

g m

-3)

3210-1

m/z 57

m/z 202

m/z 226

Dmob100 nm150 nm200 nm250 nm300 nm350 nm400 nm

18

Calculation of Black Carbon Content, Particle Density, and Dynamic Shape Factor

Assumptions: 1. No internal voids2. Dynamic shape factor is the same in continuum and free-molecular regimes3. BC, PAH, aliphatic species are immiscible4. Component densities estimated (ρBC = 2.0 g/cc, ρPAH = 1.3 g/cc, ρAL = 0.85 g/cc)

System of equations relating equivalent diameter and mass:

dm = dve χCc(dm)Cc(dve)

dva = dveρpρ0

1χ mp = mBC + mPAH + mAL = (π/6) dve

3 ρp

The system is underdetermined (3 equations, 4 unknowns: dve, ρp, χ, mBC). However, using assumptions 3 and 4, ρp may be expressed as:

ρp =mBC + mPAH + mALmBCρBC

mPAHρPAH

mALρAL

+ +

The system has been reduced to 3 equations with 3 unknowns, and can be solved for mBC, ρp, and χ.

D_mob = d * X

D_va = pro * d / X

19

Aging of fractal combustion particles

100

0

200

300

400

500

100

0

200

300

400

500

12

8

4

dM/d

logD

a(µ

gm

-3)

12

8

4

dM/d

logD

a(µ

gm

-3)

20

15

10

5

03 4 5 6 7

1002 3 4 5 6 7

10002

20

15

10

5

03 4 5 6 7

1002 3 4 5 6 7

10002

20

15

10

5

03 4 5 6 7

1002 3 4 5 6 7

10002

Aerodynamic Diam. (nm)

0

Ammonium Nitrate Sulphate Organics Chloride Diesel Truck Emission

~1 sec average

Fixed Site~100 min average(morning rush hour)

Photochemical processing and

transport(afternoon)

EMISSIONS

URBANAging/Processing

Urban Down WindOxidized and internally mixed

with secondary organicand inorganic compounds

20

Lens Transmission issues

Reasonable understanding of current lenses

Peter Liu, Leah Williams, John Jayne

Ann Middlebrook, Brendan Matthew, Ken Docherty

“standard” vs “high throughput”

some variability

New “high pressure” lens – modification of Schreiner lens

1.4

1.2

1.0

0.8

0.6

0.4

0.2

0.0

Sig

nal (

arb.

uni

ts)

2 3 4 5 6 7 8 9100

2 3 4 5 6 7 8 91000

Dva (nm)

TransEff, NH4NO3nh4no3_sep0104_CE, Peter Liu, N transeff_countsEl_model_new_585torr, Deng calc Trans_760torr, Deng, calc. AN_ObsCalcRat (AN_ARI) DEHS_ObsCalcRat (DEHS_ARI) SN_ObsCalcRat (NaNO3_ARI) DEHS_dec1304_CE dehs_small_dec1404_CE NaNO3_CE_dec1304 ARI2_Na_TOF_CPC ARI2_NH4_TOF_CPC SN_2_obspredrat

21

High Pressure Lens Assembly

-0.36 -0.30 -0.24 -0.18 -0.12 -0.06 0.00-0.015

-0.010

-0.005

0.000

0.005

0.010

0.015

Nozzle

Diameter of pinhole is 120/140/160 microns.Diameters of connection and lens tube are 4.4mm.Diameter of the nozzle is 0.8mm.

LensConnectionPinhole

Y (m

)

X (m)

Deng Rensheng (MIT)

Transmission Efficiency

O140, Q=149.2sccm, Window: 0.21- 4µm

10 100 1000 10000

0.0

0.2

0.4

0.6

0.8

1.0

10 100 1000 10000

O160 O140 O120

Tran

smis

sion

effi

cien

cy

Dp, nm

O120, Q=108.0sccmWindow: 0.135-4.5µm

O160, Q=198.0sccmWindow: 0.33-3.4µm

Deng Rensheng (MIT)

22

Light Scattering Probe – Eben Cross (Tim Onasch)

In-situ quantification of the refractory and/or particle bounce events for single particles

30

20

10

0

ls_s

ig

5x10-343210time-of-flight

1.00.80.60.40.20.0

tof_sig

50

40

30

20

10

0

ls_s

ig

4x10-33210time-of-flight

250

200

150

100

50

0

tof_sig

Refractory or Particle Bounce Event

Non-Refractory Particle Event NH4NO3

(NH4)2SO4

23

15

10

5

0

Mas

s C

once

ntra

tion

(µg

m-3

)

12:00 PM8/12/2004

3:00 PM 6:00 PM 9:00 PM

Date and Time

Ammonium Nitrate Sulphate Chloride Organics PAH

High and Low RH Nitrate600

500

400

300

200

100

0

dN/d

LogD

va

3 4 5 6 7 8 9100

2 3 4 5 6 7 8 91000

Dva

3

2

1

0

ce_b

ounc

e

dNdLogD_LS dNdLogDtoflsd_30_46 ce = 1.08+/- 0.3

NH4NO3

15

10

5

0

Mas

s C

once

ntra

tion

(µg

m-3

)

12:00 PM8/12/2004

3:00 PM 6:00 PM 9:00 PM

Date and Time

Water Ammonium Nitrate Sulphate Chloride Organics PAH

RH = 54% Sulfate

150100

500dN

/dLo

gDva

3 4 5 6 7100

2 3 4 5 6 71000

Dva

0.40.30.20.10.0 ce

_bou

nce

dNdLogD_LS dNdLogDtoflsd_48_64_80_81_98 ce = 0.16 +/- 0.15

DRY (NH4)2SO4

24

15

10

5

0

Mas

s C

once

ntra

tion

(µg

m-3

)

12:00 PM8/12/2004

3:00 PM 6:00 PM 9:00 PM

Date and Time

Water Ammonium Nitrate Sulphate Chloride Organics PAH

RH = 84% Sulfate

600

400

200

0

dN/d

LogD

va

3 4 5 6 7100

2 3 4 5 6 71000

Dva

1.2

0.8

0.4

0.0

ce_b

ounc

e

dNdLogD_LS dNdLogDtoflsd_48_64_80_81_98 ce = 0.81 +/- 0.12

WET (NH4)2SO4

250

200

150

100

50

0

dNdL

ogD

_LS

4 5 6 7 8 91000

2

Dva

1.2

0.8

0.4

0.0

ce_bounce

dNdLogD_LS dNdLogD_NO3_30_46 dNdLogD_org_43_44 dNdLogD_SO4_48_64

Sulfate Event 7/30/04 Species Mean ce sdev

NO3 0.53 0.10

SO4 0.62 0.17

Org 0.65 0.12

Region over which the mean was calculated

Ambient Particles

Chebogue Point

Nova Scotia

25

1.4

1.2

1.0

0.8

0.6

0.4

0.2

0.0

AMS/

PIL

S C

E (S

O4

or N

O3)

1.61.41.21.00.80.60.40.20.0

Light Scattering CE

85

80

75

70

65

60

55

Relative H

umidity (%

)

Polydisperse Aerosols Ammonium sulfate Ammonium nitrate 25:75 AS:Org mixture 50:50 AS:Org mixture 75:25 AS:Org mixture Organic acid mixture 50:50 AN:Org mixture Ambient

Peter Decarlo

26

20

15

10

5

0

ug/m

^3

7/25/2004 7/27/2004 7/29/2004 7/31/2004dat

1.81.71.61.51.41.31.2d

ensi

ty(g

/cc)

1.4s

SO4 Org NH4 NO3 MAAP

Aerodynamic and Optical Diameters Particle Density

Eben Cross, Boston College

Density:OpticalChemical

CnH2n+0,2 ----> CmH2m±1+27, 29, 41, 43, 55, 57, 69, 71, ...

CnHmOy ----> H2O+ , CO+ , CO2+ , C2H3O+18 28 44 43

29, 55, ….

Organic Mass Spectra

Following flash vaporization at ~600oC

e-

e-

C5H9+C4H7+C3H5+

27

Organic Mass Distributions

• Small mode, hydrocarbon-based, primary traffic organic PM• Accumulation mode oxidized organic PM

Morning Rush Hour

Accumulation mode

m/z = 57C4H9+

‘Traffic’ mode m/z = 44CO2+


m/z = 44CO2+

Accumulation mode

‘Traffic’ mode

m/z = 57C4H9+

Morning Rush Hour

Investigate specific mass spectra during morning rush hour and late afternoon

28

Hydrocarbon and oxidized organics

2.0

1.5

1.0

0.5

0.0

Nitr

ate

Equi

vale

nt M

ass

Con

cent

ratio

n (µ

g m

-3)

150140130120110100908070605040302010m/z

Species

Air 295 ± 0.2Water 1.62 ± 0.1Ammonium 0.896 ± 0.02Nitrate 0.486 ± 0.007Sulphate 1.98 ± 0.01Chloride 0.0727 ± 0.007PAH 0.00739 ± 0.004Organics 13.1 ± 0.05Others 1.38 ± 0.2

m/z = 44CO2+

16

14

12

10

8

6

4

2

0

dM/d

logD

va (µ

g m

-3)

2 3 4 5 6 7 8 9100

2 3 4 5 6 7 8 91000

2


Organics

5

4

3

2

1

0

Nitr

ate

Equi

vale

nt M

ass

Con

cent

ratio

n (µ

g m

-3)

150140130120110100908070605040302010m/z

Species

Air 293 ± 0.3Water 1.53 ± 0.2Ammonium 1.81 ± 0.03Nitrate 1.79 ± 0.02Sulphate 2.29 ± 0.03Chloride 0.901 ± 0.02PAH 0.066 ± 0.008Organics 39.2 ± 0.1Others 2.77 ± 0.2

m/z = 43C3H7+

30

20

10

0

dM/d

logD

va (µ

g m

-3)

2 3 4 5 6 7 8 9100

2 3 4 5 6 7 8 91000

2


Organics

Small traffic mode

Hydrocarbonseries

m/z = 57C4H9+

AMS Mass Spectral Tracersm/z 57 (mostly C4H9+): Hydrocarbon-like Organic Aerosol (HOA; likely POA)

m/z 44 (mostly CO2+): Oxygenated Organic Aerosol (OOA; likely SOA)

Gas & EC data from E. Wittig & R. Subramanian (CMU)

29

0.00

0.05

0.10

0.15

0.20

0.25

0.30

050

100150

200250

23:20:00 23:30:00 23:40:00

23:50:00 00:00:00 00:10:00 00:20:00

Sign

al In

tens

ity

m/z

Sampling timet0t1

t2t3

......


Deconvolve AMS Organic Data: MathematicsAn AMS organic mass spectrum is the linear superposition of the mass spectra of individual organic species.

= + E

Residual matrix

×

mass spectra matrix of n components

⎥⎥⎥⎥

⎦

⎤

⎢⎢⎢⎢

⎣

⎡

nttt

n

n

ccc

cccccc

,2,1,

,22,21,2

,12,11,1

L

LLLL

L

L

Conc. matrix of n components

⎥⎥⎥⎥

⎦

⎤

⎢⎢⎢⎢

⎣

⎡

300,2,1,

300,22,21,2

300,12,11,1

nnn msmsms

msmsmsmsmsms

L

LLLL

L

L

⎥⎥⎥⎥

⎦

⎤

⎢⎢⎢⎢

⎣

⎡

300,2,1,

300,22,21,2

300,12,11,1

ttt mmm

mmmmmm

L

LLLL

L

L

t

iRow: mass spec

Column: t series

?Our approach:

Custom PCA initializes with

unique MS tracers

Nt: 1,000 ~ 10,000

30

Indications of other (small) components or small variation in the spectra

Hydrocarbon-type OAOxygenated OA

HOA and OOA Time Series in Pittsburgh

31

Mexico City Map

Measurements were obtained at several fixed sites in Mexico City(Xalostoc, Merced, Cenica, Pedregal, and Santa Ana)

with differing influences of air pollution sources and meteorology.

Urban Aerosols – City Center and Down Wind

• City center

• Residential urban

• Boundary site

32

Oxygenated organic composition from AMS

0.8

0.6

0.4

0.2

0.0

m/z

44

6420Organics

6

4

2

0

Org

anic

s (u

g/m

3)

12:00 AM7/9/2004

Date and Time

High O:C Ratio (m = 0.17) Medium O:C Ratio (m = 0.10) Low O:C Ratio (m = 0.03)

33

0.25

0.20

0.15

0.10

0.05

0.00

m/z

44 (C

O2+

) /

orga

nic

6050403020100

Ozone (ppb)

350300250200150100500

Wind Direction

Secondary Organic Oxidation CO2+ (m/z 44) vs Ozone

Sulfate NR Organic Nitrate

Northwest – Southerly Aerosol Loading

14

12

10

8

6

4

2

0

dM/d

logD

va (µ

g m

-3)

5 6 7 8 9100

2 3 4 5 6 7 8 91000

2


Nitrate Sulphate Organics Ammonium

4

3

2

1

0

dM/d

logD

va (µ

g m

-3)

5 6 7 8 9100

2 3 4 5 6 7 8 91000

2


Nitrate Sulphate Organics Ammonium

1 0

8

6

4

2

0

7 /2 6 /20 0 4 7 /2 9 /200 4 8 /1 /2004d a t

34

1 .0

0 .8

0 .6

0 .4

0 .2

0 .0

Nitr

ate

Equ

ival

ent M

ass

Con

cent

ratio

n (µ

g m

-3)

1 5014 013012 01101 0090807 0605040302 010m/z

Sp ecies

Air 89.6 ± 0.03W ater 0 .424 ± 0.02Am monium 0.2 93 ± 0.005Nitrate 0.07 65 ± 0 .0008MSA 0 ± 0Sulphate 1.59 ± 0.0 03Chlo ride 0 .0008 83 ± 0.0006PAH -0.000 657 ± 0.001Orga nics 1.27 ± 0.006Others 0.149 ± 0.004

Southerly airflow

0 .8

0 .6

0 .4

0 .2

0 .0

Nitr

ate

Equ

ival

ent M

ass

Con

cent

ratio

n (µ

g m

-3)

1 501401301 201101009 08070605040302010m /z

Spe cies

A ir 89 .6 ± 0 .03W ater -0.11 4 ± 0 .02A mm on ium 0.23 6 ± 0 .005N itrate 0.192 ± 0.0 01S ulphate 0.411 ± 0.0 02C hloride 0.00525 ± 0.0 006P AH 0.000 348 ± 0.000 9O rgan ics 3.96 ± 0.00 7O th ers 0 .643 ± 0.00 7

Northwest airflow

0 .6

0 .5

0 .4

0 .3

0 .2

0 .1

0 .0

Nitr

ate

Equ

ival

ent M

ass

Con

cent

ratio

n (µ

g m

-3)

1 501401301 201101009 08070605040302010m /z

S pec ies

Air 89.6 ± 0.03W ate r -0. 114 ± 0.02Am mo niu m 0. 236 ± 0.00 5Nitrate 0.19 2 ± 0 .001Sulpha te 0.4 11 ± 0 .002Chloride 0.005 25 ± 0 .0006PA H 0.00 0348 ± 0.0 009O rg anic s 3.9 6 ± 0.007O thers 0.643 ± 0.007

Northwest airflow

0 .30

0 .25

0 .20

0 .15

0 .10

0 .05

0 .00

Nitr

ate

Equ

ival

ent M

ass

Con

cent

ratio

n (µ

g m

-3)

1 501 401301201 10100908070605040302010m /z

Sp ec ies

A i r 8 9 .6 ± 0.03W ater 0 .424 ± 0.02Am m o nium 0.2 93 ± 0 .005N itrate 0 .07 65 ± 0 .0008M SA 0 ± 0Sulphat e 1.59 ± 0.0 03C hlo ride 0 .0008 83 ± 0 .000 6PA H -0.000 657 ± 0.001Orga nic s 1.27 ± 0.0 06Ot hers 0.149 ± 0.0 04

Southerly a irflow

CO2+ (m/z 44)

C2H3O+ (m/z 43)

35

“First” Single Particle - Mixed (NH4)2SO4 and Organic

Drewnick, Hings, DeCarlo, Jimenez et al.

36

1.5

1.0

0.5

0.0

1600155015001450140013501300

QMSApproximately 1.5 ug/m3 of sulfate, 30 second acquisition

m/z 48, SO+ m/z 64, SO2+

FIG 2a

37

1.0

0.8

0.6

0.4

0.2

0.0

4100400039003800370036003500

40

30

20

10

0

x10-

3

4100400039003800370036003500

ToF-AMSApproximately 1.5 ug/m3 of sulfate, 30 second acquisition

m/z 48, SO+m/z 64, SO2+

x40

“organics”

FIG 2b

IONS

IONS

C-ToF

W-ToF

38

0 . 6

0 . 4

0 . 2

0 . 0

W M

ode

Sign

al (b

its)

4 3 . 1 04 3 . 0 84 3 . 0 64 3 . 0 44 3 . 0 24 3 . 0 04 2 . 9 8

3 0

2 0

1 0

0

V Mode S

ignal (bits)

H N 3C H N OC H 3 N 2

C 2 H 3 O C 2 H 5 NC 3 H 7

N 2H 2C OC H 2C H 4C 2 HC 2 HC 3H NC H NC H 3C 2 HC 2 HC 2 HC 3 HC 3 HC 4

D ie s e l D if f e r e n c e S p e c t r a W M o d e V M o d e

H N 3C H N O

C H 3 N 2C 2 H 3 O C 2 H 5 N

C 3 H 7

r e n c e S p e c tr a

Diesel Exhaust

WToF-AMS: m/z 43

Albumen (protein)

C2H3O+ C3H7+

DeCarlo et al,

unpublished results (2005)

V-Mode

W-Mode

FIG 4

High Resolution MS

OOA Marker

m/z 44: dominated by CO2+HOA Marker

m/z 57: dominated by C4H9+

Albumen (protein) particles Diesel Exhaust

39

VUV (10.5 eV) lamp assembly in ionization region of AMS

“softer”

ionization

Switch between EI and Photoionization

8

6

4

2

0

-2 8 910

Energy (eV)

150 140 130 120 110

Wavelength (nm)

AlkanesAlcohols

AldehydesKetones

EthersAromatic

O Kr

LiFCaF2

ArLampWindow

Acids

Organic Groups

11 1210

Single Photon - Ionization Kr at 10/10.5 eV

MgF2

40

40

30

20

10

0

500400300200100

40

30

20

10

0

x10-3

Cigarette Smoke – ToFAMS with VUV (JARI)

EI

VUV

Akiyama (JARI)

12

10

8

6

4

2

0

12010080604020

NO2- (m/z = 46)

NO3- (m/z =62)

HCOO- (m/z = 45)

CH3COO- (m/z = 59)

C2H5COO- (m/z = 73)

HSO4- (m/z = 97,99)

SO2- (m/z = 64)

SO3- (m/z = 80)

Cl- (m/z = 35,37)

CNO- (m/z = 42)

NO- (m/z = 30)

CN- (m/z = 26)

OH- (m/z = 17)

O- (m/z = 16)

Electron attachment (neg ion) spectrum of ambient (Riverside)

41

Li attachment spectrum of pinene – ozon experiment

220210200190180170160150140130m/z

220210200190180170160150140130m/z

pinic acid + Li+ (m/z = 192)

pinonic acid + Li+ (m/z = 190)

norpinic acid + Li+ (m/z = 178)

norpinonic acid + Li+ (m/z = 176)

pinonaldehyde + Li+ (m/z = 174)

norpinonaldehyde + Li+ (m/z = 160)

dialdehyde + Li+ (m/z = 146)

Cs+ (m/z = 133)

Findings from EPA’s Findings from EPA’s Particulate Matter Particulate Matter

Supersites ProgramSupersites Program

Cover of JGR-Atmospheres, in press

Data from:Zhang et al., ES&T 38, 4797, 2004

JGR 110 (D07S09), 2005Stainer et al, ES&T; JGR

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