Aerosol Chemical Speciation Monitor (ACSM) Advances

Aerosol Chemical Speciation Monitor (ACSM)

Thermal Vaporization &

Electron Impact

Ionization

Aerodynamic lens

Particle Beam

Generation

Particle

Composition

Data AcquisitionComputer

TOF

or

Q-M

S

Turbo Pumps

Aerosol

SamplingIn from cyclone

Out to sampling pump

Filter

3-way Valve

Ng, et al., Aerosol Sci. Technol., 45:7, 770-784, 2011

No Sizing

9/8/2018 AMS Users Meeting 2016 2

Quadrupole, Q-ACSM Time-of-Flight, ToF-ACSM

9/8/2018 AMS Users Meeting 2016 3

Von der Weiden et al., Atmos. Meas. Tech., 2, 479-494, 2009.

Improved aerosol sampling system for efficient delivery of PM2.5 to aerodynamic lens

Intermediate Pressure Lens (IPL) delivers PM2.5 to detector

PM2.5 Capable ACSM – Laboratory CharacterizationXu et al., AS&T, 2016

9/8/2018 AMS Users Meeting 2016 4

Capture Vaporizer effectively vaporizes all large particles for complete detection of NR-PM2.5

PM2.5 Capable ACSM – Ambient CharacterizationZhang et al., ACPD, 2017

9/8/2018 AMS Users Meeting 2016 5

PM2.5 Capable ACSM – Ambient CharacterizationZhang et al., ACPD, 2017

9/8/2018 AMS Users Meeting 2016 6

Towards simplified calibration of ACSM - electrospray

Inlet (e.g., CPC)

Vacuum Pump

10 mCiPolonium Dryer/denuder

Needle Valve

AMS inletSyringe pump

Capillary

Grounded platewith orifice

sheath gas

Micro-positioner

static neutralizer

Capillary Grounded plate

Plastic cover

3025201510

50

AM

S O

rg d

M/d

log

10d

va (

µg

m-3

)3 4 5 6 7 8 9

1002 3 4 5 6 7 8 9

PToF Dva (nm)

30x109

2520151050

SM

PS

dV

/dlo

g10 d

M

3 4 5 6 7 8 9100

2 3 4 5 6 7 8 91000

SMPS Dm (nm)

15

10

5

0

15

10

5

0

20x109

15

10

5

0

15x109

10

5

0

1st Run

2nd Run

3rd Run

Dva = Dm * 0.91

Want repeatable (narrow) distribution to eliminate particle sizingWorked for oleic acid in acetonitrile but not for aqueous or saltsPractical concerns as well (e.g. radioactive source)

9/8/2018 AMS Users Meeting 2016 7

Towards new calibrations techniques – gas introduction

9/8/2018 AMS Users Meeting 2016 8

m/z

44

dif

f

CO2 Input / ppm

Slope = 1.37e-13

1e6*0.78*1.37e-13 amps/ppm = 1.06e-7 amps

Our airbeam signal is 1e-7 amps

Gases are easier to use for calibration than aerosols (by far).We get a nice calibration curve at varying CO2 concentrations.But what does this add?

Towards simplified calibration – Ultrasonic nebulizer and OPC

9/8/2018 AMS Users Meeting 2016 9

Generate particles with UN that are large enough to be counted by the OPCFeed ACSM and OPC the polydisperse and integrate the size distribution to calculate the input mass

Towards simplified calibration – Ultrasonic nebulizer and OPC

9/8/2018 AMS Users Meeting 2016 10

Towards simplified calibration – Ultrasonic nebulizer and OPC

9/8/2018 AMS Users Meeting 2016 11

UN/OPC Calibration Standard ACSM Calibration