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AMS Collection Efficiency

Tim Onasch, Eben Cross, Doug WorsnopAerodyne

Tim Bates, Trish QuinnPMEL

Outline• CE issues

– Size– Shape– Phase

• Ron Brown and Aerodyne laboratory-generated aerosol tests– AMS – PILS IC comparison (Ron Brown)– Humidified inlet (Ron Brown)– Poly-disperse BWP analysis (Ron Brown)– Mono-disperse BWP analysis (Aerodyne)– Light scattering probe analysis (Aerodyne)

CE Issues• SIZE:

– Particle transmission loss at the critical orifice and lens. (Leah Williams, Peter Liu, Ann Middlebrook)

– Large particles may not fully vaporize or may breakup? (Leah Williams, Peter Liu)

– Particles can be focused to different positions on the AMS vaporizer as a function of particle size. (Ann Middlebrook, Eben Cross)

• SHAPE: – Nonspherical particles are not as well focused as spherical liquid

droplets. (CU, Aerodyne)

• PHASE: – Liquid particles “splat” on AMS vaporizer.– Solid particles and particles with low volatility can bounce off the

vaporizer resulting in loss of signal.

FOCUS: Collection Efficiency AFTER passing through the lens.- Phase and Size

Beam Width Probe

Vaporizer

Top View

Front View

Regularly-shaped particles (red)

Not blocking beam Blocking particle beam

Beam Width Probe (with controllable position)

Tightly-focused particle beam

Irregularly-shaped particles (black)Wide particle beam

Some irregular particles may miss vaporizer

NEAQS-ITCT 2004

AMS Mass Loadings

20

15

10

5

0

Mas

s Lo

adin

g (u

g/m

3)

7/11/2004 7/21/2004 7/31/2004 8/10/2004Date and Time

org so4 no3 nh4

AMS – PILS SO4 comparison20

15

10

5

0

Mas

s Lo

adin

g (u

g/m

3)

7/7/2004 7/9/2004 7/11/2004 7/13/2004

Date and Time

org so4 no3 nh4 NSS SO4 PILS

2.01.00.0NH4:SO4 Ratio

20

15

10

5

0

PILS

NSS

Sul

fate

20151050AMS Sulfate

2.0

1.5

1.0

0.5

0.0

NH

4:SO

4 Ratio

Collection Efficiency is directlyrelated to Sulfate acidity

Test #1 Polydisperse AS and AN

RH = 60%12

10

8

6

4

2

0

Mas

s C

once

ntra

tion

(µg

m-3

)

1:00 PM7/23/2004

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

Date and Time

Water Ammonium Nitrate Sulphate Chloride Organics PILS Nitrate PILS Sulfate PILS Ammonium

Test #1 AMS – PILS comparison10

8

6

4

2

0

PILS

1086420AMS

RH = 60% Sulfate Nitrate line1to1 line2to1 line3to1

Test #1Wire Analysis

1.4

1.2

1.0

0.8

0.6

0.4

0.2

0.0

% T

rans

mis

sion

54321

Wire Position

Ammonium Sulfate (1.7 ug/m3) Ammonium Nitrate (2.2 ug/m3) 1.0

0.8

0.6

0.4

0.2

0.0

% T

rans

mis

sion

1:00 PM7/23/2004

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

Date and Time

100

80

60

40

20

0

Relative H

umidity (%

)

no30 no31 no32 no33 no34 no35 relative_humidity

1.0

0.8

0.6

0.4

0.2

0.0

% T

rans

mis

sion

1:00 PM7/23/2004

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

Date and Time

100

80

60

40

20

0

Relative H

umidity (%

)

so40 so41 so42 so43 so44 so45 relative_humidity

• 1 mm wire – 5 overlapping positions selected with an apparent 0.5 mm wire.• wire positions 1 and 5 are still fully on horizontal axis of vaporizer.

Test #1Conclusions

• AMS : PILS = 1 for AN• AMS : PILS = 0.3 for AS• AN and AS particle beam spread are

similar• AN and AS particles appear to all hit

vaporizer

Mass Loadings showing Particle Bounce

Test #2 Polydisperse AS Variable RH

30

25

20

15

10

5

0

dM/d

logD

va (µ

g m

-3)

1002 3 4 5 6 7 8 9

10002

Vacuum Aerodynamic Diameter (nm)

Water Ammonium Sulphate

8

6

4

2

0

Mas

s C

once

ntra

tion

(µg

m-3

)

4:00 PM7/26/2004

5:00 PM 6:00 PM 7:00 PM 8:00 PM

Date and Time

6.0x106

5.04.0

Airbeam

2.01.61.20.8

80

75

70

65

60

55

50

RH

(%)

00000

000

00000

00000

00000

00000

00000

00000

00000

00000

00000

0 0

3 5 5 5 5 5 5 5 5 5 5

Water Ammonium Nitrate Sulphate Chloride Organics PILS SO4 PILS NH4

Test #2AMS – PILS comparison

8

6

4

2

0

PILS

86420

AMS

nh4_ugm3 nss_so4_ugm3 line1to1 line2to1 line3to1

80

75

70

65

60

55

50

Relative H

umidity (%

)

1.4

1.2

1.0

0.8

0.6

0.4

0.2

0.0

Wire

Tra

nsm

issi

on

4:00 PM7/26/2004

5:00 PM 6:00 PM 7:00 PM

Date and Time

80

75

70

65

60

55

50

RH

(%)

W ire Positions (0 = no wire) so40 so41 so42 so43 so44 so45 relative_humidity

Test #2Wire Analysis

2.0

1.8

1.6

1.4

1.2

1.0

0.8

0.6

0.4

0.2

0.0

% T

rans

mis

sion

43210wire step number

High Relative Humidity sulfate ammonium

Low Relative Humidity sulfate ammonium

80

75

70

65

60

55

50

RH

(%)

4:00 PM7/26/2004

4:30 PM 5:00 PM 5:30 PM

Date and Time

10

8

6

4

2

0

Mas

s C

once

ntra

tion

(µg

m-3

)

5.0x106

4.03.0

Airbeam

1.00.90.80.70.60.5

000000000000000000000000000000000000000000000000000000 0

12

3

34 4

5 Water Ammonium Nitrate Sulphate Chloride Organics PILS SO4 PILS NH4

• 1 mm wire – 5 overlapping positions selected with an apparent 0.5 mm wire.• wire positions 1 and 5 are still fully on horizontal axis of vaporizer.

Test #2Conclusions

• AMS : PILS dependent upon RH• AMS : PILS NH4 ranges from <1/3 to 1• AMS : PILS SO4 ranges from <1/3 to 0.9

RH controls AMS SO4 CE

Test #3Polydisperse AS, AS+Org, AN

Variable RH

Organics used for this test are a mixture of :

Succinic Acid Malonic Acid

Test #3 Polydisperse AS, AS+Org, AN

Variable RHAS

50% AS

50% Org

25% AS

75% Org

75% AS

25% OrgAN 50% AN

50% OrgOrg

8

6

4

2

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

100

80

60

40

20

0

Relative H

umidity

Ammonium relative_humidity Nitrate no3_ugm3 Sulfate nh4_ugm3 Chloride nss_so4_ugm3 Organics

Test #3: AMS – PILS SO4 comparison6

5

4

3

2

1

0

PILS

IC

6543210

AMS

nss_so4_ugm3 line1to1 line2to1 line3to1

90

85

80

75

70

65

60

Relative H

umidity

6

5

4

3

2

1

0

PILS

IC

6543210

AMS


90

85

80

75

70

65

60

Relative H

umidity

100% AS50% AS

50% Org

25% AS

75% Org

75% AS

25% Org

6

5

4

3

2

1

0

PILS

IC

6543210

AMS


90

85

80

75

70

65

60

Relative H

umidity

6

5

4

3

2

1

0

PILS

IC

6543210

AMS


90

85

80

75

70

65

60

Relative H

umidity

Test #3AMS – PILS

SO4 comparison

1.0

0.8

0.6

0.4

0.2

0.0

AMS/

PIL

S S

O4

Rat

io

1.00.80.60.40.20.0

Sulfate Mass Fraction

90

85

80

75

70

65

60

Relative H

umidity

1.0

0.8

0.6

0.4

0.2

0.0

AMS/

PIL

S S

O4

Rat

io

1.00.80.60.40.20.0

Organic Mass Fraction

90

85

80

75

70

65

60

Relative H

umidity

6

5

4

3

2

1

0

PILS

IC

6543210

AMS

line1to1 line2to1 line3to1

90

85

80

75

70

65

60

Relative H

umidity

Ambient Sampling at High RH

20

15

10

5

0

PIL

S N

SS S

ulfa

te

20151050AMS Sulfate

20

15

10

5

0

Mas

s Lo

adin

g (u

g/m

3)

7/11/2004 7/21/2004 7/31/2004 8/10/2004Date and Time

806040

9050Relative Humidity

Ambient DataAMS to PILS comparison

AMS NH4:SO4 RatioAMS Organic Mass Fraction

15

10

5

0

PILS

NSS

Sul

fate

151050AMS Sulfate

2.0

1.5

1.0

0.5

0.0

15

10

5

0

PILS

NSS

Sul

fate

151050AMS Sulfate

1.0

0.8

0.6

0.4

0.2

Test #3Conclusions

• AMS:PILS sulfate dependent upon RH, when aerosol are pure ammonium sulfate.

• AMS:PILS sulfate is not very dependent upon RH when aerosols are internal mixture of sulfate and solid organic acids.

• AMS:PILS sulfate IS dependent upon organic (or sulfate) mass fraction in the internally mixed sulfate and organic particles.

RH does NOT control ambient AMS SO4 CE, when organics are present.

Laboratory Experiments with Light Scattering Module

Eben Cross, Tim OnaschAMS Users Meeting 10-07-04

Percent Coverage of the Laser Beam on the Oven

Oven Diameter = 3.8 mm

Laser beam 1/e height 2.0 mm at the oven 63.8%* Coverage

Laser beam height for 100% particle detection = 1.7 mm 55%* Coverage

*NOTE that these calculations are based on the long chamber (5 Port) version of the AMS

Particle Walk in Vertical DirectionNormalized

100

80

60

40

20

0

% C

ount

ed L

S /

CP

C a

nd T

OF/

CP

C N

itrat

e

3210-1-2dy_OVEN (mm)

80

60

40

20

LS/C

PC

Sulfate

18

16

14

12

10

8

6

4

%TO

F/C

PC

Sul

fate

Laser Trace w/ Nitrate Oven Trace w/Nitrate Laser Trace w/Sulfate Oven Trace w/Sulfate

• 350 nm Ammonium Nitrate – well defined vaporizer (dark red) and laser beam (dark blue) signal.• 350 nm Ammonium Sulfate – less well defined vaporizer (light red) and laser beam (light blue) signal.

Particle Walk in Vertical DirectionTo Scale

100

80

60

40

20

0

% C

ount

ed L

S /

CP

C a

nd T

OF/

CP

C N

itrat

e

3210-1-2dy_OVEN (mm)

100

80

60

40

20

0

LS/C

PC

Sulfate

100

80

60

40

20

0

%TO

F/C

PC

Sul

fate

Laser Trace w/ Nitrate Oven Trace w/Nitrate Laser Trace w/Sulfate Oven Trace w/Sulfate


Counting Statistics showing Particle Bounce

Fractal Soot Collection Efficiency

• Even fractal particles strike the AMS vaporizer with a high efficiency!!

• Jay Slowik’s work

Beam Probe Resultsw/ HTP Lens Rotated

Lens in initial position. Lens rotated ~ 180 degrees.

2000

1500

1000

500

0

dM/d

logD

va (µ

g m

-3)

3 4 5 6 7 8 9100

2 3 4 5 6 7 8 91000


ug_NO3_r1014 ug_NO3_r1015 ug_NO3_r1016 ug_NO3_r1017 ug_NO3_r1018 ug_NO3_r1019 ug_NO3_r1020 ug_NO3_r1021 ug_NO3_r1022 ug_NO3_r1023

4/5/04160 micron orif icew/o p-control inlet

AN solutionHTP Lens rotated

2000

1500

1000

500

0

dM/d

logD

va (µ

g m

-3)

3 4 5 6 7 8 9100

2 3 4 5 6 7 8 91000



4/2/04160 micron orif icew/o p-control inlet

AN solution

Smaller particles focused to the RIGHT of larger particles.

Smaller particles focused to the LEFT of larger particles.

Beam Probe ResultsStandard Lens 4/6/04

200

150

100

50

0

Mas

s C

once

ntra

tion

(µg

m-3

)11:10 AM4/6/2004

11:15 AM 11:20 AM 11:25 AM 11:30 AM

Date and Time

200x103

150

100

50

0

CP

C (#/cm

3)

1051 1052 10531054

1055

1056

10571058

1059 1060250

200

150

100

50

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



4/6/04Standard Lens

100 micron orificeAN solution

w/o P-control inlet

Particle Walk in Horizontal DirectionNormalized

80

60

40

20

0

% C

ount

ed /

CPC

3210-1dx_OVEN (mm)

70

60

50

40

30

20

10

16

14

12

10

8

6

4

2


1.4

1.2

1.0

0.8

0.6

0.4

0.2

0.0

Rel

ativ

e A

ttenu

atio

n of

the

mas

s

43210Wire Position

NO3 SO4

Estimated center of the sulfate beam 350nm monodisperse

Shift 0.25mm at the BWP

LEFTRIGHT

This is the attentuation for the 350nm systems used in the previous particle walk experiments. The beam width probe infosays that the sulfate beam is slightly off center. The beam positions are supposed to run from left to right according to the model program, but I have the module flipped upside down, so it is really right to left 0-4. Therfore, the position where the true center of the sulfate beam is located is slightly LEFT. Left on the apparatus corresponds to the non-laser side of the chamber, so thisis the same as the ellipsoid hole excess side (furthest from the laser beam)

0.25 mm movement at the BWP position = 0.325 mm at the oven. So that is why I shifted the LS/CPC sulfate line in the previous walk plots for the x direction.

80

60

40

20

0

% C

ount

ed /

CPC

3210-1dx_OVEN (mm)

70

60

50

40

30

20

10

16

14

12

10

8

6

4

2

80

60

40

20

0

% C

ount

ed /

CPC

3210-1-2dx_OVEN (mm)

70

60

50

40

30

20

10

16

14

12

10

8

6

4

2

AMS Collection Efficiency - welcome | CIREScires.colorado.edu/jimenez-group/UsrMtgs/UsersMtg5/...–...

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