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Overview of CIMS Applications
Doug WorsnopARI/PKU AMS/CIMS Users Meeting
Tuesday, 9 May
Kulmala et al., 2013, Science
BSMA
API-ToFMS(Tofwerk)
Mikael Ehn, Heikki Junninen
Atmospheric (pressure) Ions
Negative ion spectra from Hyytiälä
DAY
NIGHT
C10H14O12N- ?
Negative ion spectra from Hyytiälä
DAY
NIGHT
C10H14O12N- ?
The short life of an ion
O2 O2-
X
X-
O2
A
A+
e-
…
…NO3- HSO4
-
Ions in Air: few minutes
The short life of an ion
O2 O2-
X
X-
O2
…NO3- HSO4
-
CIMS
APi-TOF
CIMS: High NO3- fraction of a second
Ions in Air: Low NO3- few minutes
Negative ion spectra from Hyytiälä
DAY
NIGHT
C10H14O12N- ?
CI-APi-TOF for neutral compound measurements
reflector
detector
3-stageturbopump
Scrollpump
Flowcontrol
Diaphragmpump
103
mba
r
Acquisition
Timing and control
Dataprocessing
Compressor
Filters , Flowcontrol
HNO3 ,Acetone etc
-”Eisele type” inletdesign.-Sheath flow 20 lpm,includes charger ions.-Total flow 30 lpm-> sample flow 10 lpm-Sample mixing withelectric field-APi samples 0.8 lpm
tofTools
ELVOCC10,C20 in the gas phase
O/C > 0.7
ELVOCC10,C20 in the gas phase
O/C > 0.7
Nucleation, ClustersNanoparticle growth
Ehn et al, Nature, 2014
also see Crounse et al, JPC Letters, 2013
Auto-oxidation
A-pinene + O3 addition of (NH4)2SO4 seedYield ~ 7+/- 4% reduces gas ELVOC increases condensed
SOA
0.4
0.3
0.2
0.1
0.0
m/z
44
/ org
ra
tio
2.01.51.00.50.0 O/C ratio
Oxalic Acid
Fulvic Acid
Oleic Acid + Ozone
PSI Chamber
AMS Observations
f44 vs O/C
2004
ELVOC SVOC
Kirkby,Curtius,Carslaw,Baltensperger,Kulmala,(Worsnop,
Donahue)
+theCLOUD KIDS
Negative Ion Composition
Schobesberger, et al, PNAS18
(C2H6N2)n(H2SO4)nHSO4-
(H2SO4)nHSO4-
(NH3)n(H2SO4)nHSO4-
(CaHbOc)n(H2SO4)nHSO4-
Boreal Forest
< 1 ppt
APi-TOF data confirm:Organics participate in cluster formation from
the very beginning
Riccobono et al., Sceince, 2014
Ionization Techniques
Electron Impact (“hard”)
R + e- R+ + 2 e- Ri+ universal
Chemical Ionization (“soft”)
proton transfer
PTRMS R + H3O+ RH+ + H2O hydrocarbons
Acetate RCOOH + C2H4O- RCOO- + C2H5O2 (carboxylic) acids
clustering
Iodide R + I- R.I- polarized species
Nitrate R + NO3- R.NO3- highly oxidized organics
[ H2SO4 + NO3- HSO4- + HNO3 ]
21
Particle-phase ON
Gas-phase ON
22
PAM Reactor Components
• UV lamps: λ = 185 and 254 nm wavelength• Humidifier, Autovalve, RH/T, Photodiode• Electronics box with ballasts and control board• Control software
AERODYNE RESEARCH, Inc. 45 MANNING ROAD, BILLERICA, MA 01821 (978) 663 9500www.aerodyne.com CACC_OPT_12_1
Potential Aerosol Mass(PAM) Oxidation FlowReactorA highly oxidizing environment thatsimulates oxidation processes ontimescales of days in the atmospherein minutes in real time.
• Laboratory or fie
l
d st udi es of secondar y aer osolgeneration via gas-phase hydroxyl (OH) radicalor ozone (O3) oxidation of gas-phase precursors.
• Heterogenous oxidation of primary aerosols.
• Compatible with gas and particle massspectrometry techniques.
• Complement to laboratory smog chamber techniques commonly used to generate secondaryorganic aerosol (SOA).
• Based on Penn State flo
w
react or desi gn int roducedby Kang et al. (2007) and further evaluated by Lambeet al. (2011).
• Field deployable.
• Wide range of oxidant exposure times attainable withdimmable UV lamps (primary emission intensity atλ = 254 nm) at high measurement throughput/resolution.
• OH/HO2 and OH/O3 ratios similar to troposphericratios. Amounts of OH, HO2, and O3 are 100 to
10,000 times larger than in the daytime troposphere,simulating days of atmospheric oxidation in minutes.
APPLICATIONS ADVANTAGES
Typical setup for measurements incorporating PAM reactor. Control software facilitates data-logging at 1 Hz and automated control with event sequencing for unattended operation (dashedgrey = analog input/output; dashed red = digital input/output)
24
Result 2b – Proof of Conceptisoprene + “high OH”
Result 4bα-pinene + “high OH”
25
26
36 ppb isoprene + “high” OH, low NOxcomparison with Krechmer et al.
Hyytiälä NO3- ToF-CIMSPMF Mass Spectral Factors
a-pinene+
O3, OH, NO (NO3)
HOM
“highlyoxidized
multifunctionalorganics”
Yan et al, ACPD, 2016