Yan
et al
.,
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2020;
6
: eaay4945 27 May 2020
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ATMOSPHERIC SCIENCE
Size-dependent influence of
NO
x
on
the
growth rates
of
organic aerosol particles
C.
Yan
1
*
†
, W.
Nie
2
*, A.
L.
Vogel
3,4‡
, L.
Dada
1
, K.
Lehtipalo
1,4,5†
, D.
Stolzenburg
6
, R.
Wagner
1
,
M.
P.
Rissanen
1
, M.
Xiao
4
, L.
Ahonen
1
, L.
Fischer
7
, C.
Rose
1§
, F.
Bianchi
1,8
, H.
Gordon
3,9||
,
M.
Simon
10
, M.
Heinritzi
10
, O.
Garmash
1
, P.
Roldin
11
, A.
Dias
3,12
, P.
Ye
13,14
, V.
Hofbauer
13
,
A.
Amorim
12
, P.
S.
Bauer
6
, A.
Bergen
10
, A.-K.
Bernhammer
7
, M.
Breitenlechner
7¶
, S.
Brilke
6,10
,
A.
Buchholz
15
, S.
Buenrostro
Mazon
1
, M.
R.
Canagaratna
14
, X.
Chen
1#
, A.
Ding
2
, J.
Dommen
4
,
D.
C.
Draper
16
, J.
Duplissy
1
, C.
Frege
4
, C.
Heyn
4
, R.
Guida
3
, J.
Hakala
1
, L.
Heikkinen
1
,
C.
R.
Hoyle
4
**, T.
Jokinen
1
, J.
Kangasluoma
1,8
, J.
Kirkby
3,10
, J.
Kontkanen
1
, A.
Kürten
10
,
M.
J.
Lawler
16
, H.
Mai
17
, S.
Mathot
3
, R.
L.
Mauldin III
13,18
, U.
Molteni
4
, L.
Nichman
19††
,
T.
Nieminen
1
, J.
Nowak
14‡‡
, A.
Ojdanic
6
, A.
Onnela
3
, A.
Pajunoja
15
, T.
Petäjä
1,2
, F.
Piel
10§§
,
L.
L. J.
Quéléver
1
, N.
Sarnela
1
, S.
Schallhart
1||||
, K.
Sengupta
9
, M.
Sipilä
1
, A.
Tomé
20
, J.
Tröstl
4
,
O.
Väisänen
15
, A.
C.
Wagner
10¶¶
, A.
Ylisirniö
15
, Q.
Zha
1
, U.
Baltensperger
4
, K.
S.
Carslaw
9
,
J.
Curtius
10
, R.
C.
Flagan
17
, A.
Hansel
1,7,21
, I.
Riipinen
22
, J.
N.
Smith
16
, A.
Virtanen
15
, P.
M.
Winkler
6
,
N.
M.
Donahue
13
, V.-M.
Kerminen
1
, M.
Kulmala
1,2,8,23
, M.
Ehn
1
, D.
R.
Worsnop
1,14,15
Atmospheric new-particle formation (NPF) affects climate by contributing to a large fraction of the cloud conden-
sation nuclei (CCN). Highly oxygenated organic molecules (HOMs) drive the early particle growth and therefore
substantially influence the survival of newly formed particles to CCN.
Nitrogen oxide (NO
x
) is known to suppress
the NPF driven by HOMs, but the underlying mechanism remains largely unclear. Here, we examine the response
of particle growth to the changes of HOM formation caused by NO
x
. We show that NO
x
suppresses particle growth
in general, but the suppression is rather nonuniform and size dependent, which can be quantitatively explained
by the shifted HOM volatility after adding NO
x
. By illustrating how NO
x
affects the early growth of new particles, a
critical step of CCN formation, our results help provide a refined assessment of the potential climatic effects
caused by the diverse changes of NO
x
level in forest regions around the globe.
INTRODUCTION
Atmospheric new-particle formation (NPF) contributes to about
half of the global tropospheric cloud condensation nuclei (CCN)
population (
1
), thereby affecting Earth’s radiation balance via aerosol-
cloud interactions (
2
). However, considerable uncertainties exist on
how atmospheric NPF and CCN production are associated with
anthropogenic emissions of different aerosol precursor gases. The
main reasons for these uncertainties are our incomplete knowledge
on the mechanisms that dictate NPF and subsequent growth of
newly formed particles to CCN sizes in the atmosphere.
1
Institute for Atmospheric and Earth System Research/INAR–Physics, Faculty of Science, University of Helsinki, 00560 Helsinki, Finland.
2
Joint International Research Labora-
tory of Atmospheric and Earth System Sciences, School of Atmospheric Sciences, Nanjing University, Nanjing, China.
3
CERN, CH-1211, Geneva, Switzerland.
4
Laboratory of
Atmospheric Chemistry, Paul Scherrer Institute, 5232 Villigen, Switzerland.
5
Finnish Meteorological Institute, Erik Palménin aukio 1, 00560 Helsinki, Finland.
6
University of
Vienna, Faculty of Physics, Boltzmanngasse 5, 1090 Wien, Austria.
7
University of Innsbruck, Institute for Ion and Applied Physics, 6020 Innsbruck, Austria.
8
Aerosol and
Haze Laboratory, Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing University of Chemical Technology, Beijing, China.
9
University of
Leeds, Leeds LS2 9JT, UK.
10
Goethe University Frankfurt, Institute for Atmospheric and Environmental Sciences, Altenhöferallee 1, 60438 Frankfurt am Main, Germany.
11
Division of Nuclear Physics, Department of Physics, Lund University, P.
O.
Box 118, SE-221 00 Lund, Sweden.
12
CENTRA and FCUL, Universidade de Lisboa, Campo
Grande, 1749-016 Lisboa, Portugal.
13
Carnegie Mellon University Center for Atmospheric Particle Studies, 5000 Forbes Ave., Pittsburgh, PA 15213, USA.
14
Aerodyne
Research Inc., Billerica, MA 01821, USA.
15
University of Eastern Finland, Department of Applied Physics, P.O.
Box 1627, 70211 Kuopio, Finland.
16
Department of Chemistry,
University of California, Irvine, CA 92697, USA.
17
California Institute of Technology, 210-41, Pasadena, CA 91125, USA.
18
Department of Chemistry and Biochemistry,
University of Colorado, Boulder, CO 80309, USA.
19
School of Earth and Environmental Science, University of Manchester, Manchester M13 9PL, UK
20
IDL Universidade
da Beira Interior, Covilhã, Portugal.
21
IONICON GesmbH, Innsbruck, Austria.
22
Department of Environmental Science and Analytical Chemistry (ACES) and Bolin Centre
for Climate Research, Stockholm University, 10691 Stockholm, Sweden.
23
Helsinki Institute of Physics, FI-00014 Helsinki, Finland.
*These authors contributed equally to this work.
†Corresponding author. Email: chao.yan@helsinki.fi (C.Y.); katrianne.lehtipalo@helsinki.fi (K.L.)
‡Present address: Institute for Atmospheric and Environmental Sciences, Goethe University Frankfurt, 60438 Frankfurt am Main, Germany.
§Present address: Université Clermont Auvergne, CNRS, Laboratoire de Météorologie Physique (LaMP), F-63000 Clermont-Ferrand, France.
||Present address: Carnegie Mellon University, Forbes Avenue, Pittsburgh, PA 15213, USA.
¶Present address: Harvard University, 18 Oxford Street, Cambridge, MA 02138, USA.
#Present address: Institute of Physics, University of Tartu, W.
Ostwaldi 1, EE-50411 Tartu, Estonia.
**Present address: Institute for Atmospheric and Climate Science, ETH Zurich, Switzerland.
††Present address: Flight Research Laboratory, National Research Council of Canada, Ottawa K1V 9B4, Canada.
‡‡Present address: NASA Langley Research Center, Hampton, VA 23681, USA.
§§Present address: Department of Chemistry, University of Oslo, 0315 Oslo, Norway.
||||Present address: Atmospheric Composition Research, Finnish Meteorological Institute, 00101 Helsinki, Finland.
¶¶ Present address: Department of Chemistry & CIRES, University of Colorado Boulder, 215 UCB, Boulder, CO 80309-0215, USA.
Copyright © 2020
The
Authors, some
rights reserved;
exclusive licensee
American Association
for the Advancement
of Science. No claim to
original U.S.
Government
Works. Distributed
under a Creative
Commons Attribution
NonCommercial
License 4.0 (CC BY-NC).
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NPF consists of two consecutive steps: particle nucleation forming
small clusters (usually 1 to 2 nm) and their further growth to larger
sizes (
3
). The efficiencies of both steps together determine the rate
of CCN formation from NPF: Particle nucleation produces an initial
pool of newly formed particles, and these particles need to grow
sufficiently fast to avoid being scavenged by the large preexisting
particles (
4
). Organic vapors play crucial roles in both steps of
NPF.
Under most tropospheric conditions, particle nucleation is
prevailingly driven by sulfuric acid (
3
,
5
), but organic vapors might
act as an important stabilizing agent of sulfuric acid clusters (
6
,
7
).
Organic vapors dominate particle growth in most tropospheric
conditions (
8
,
9
) and therefore are crucial for the survival of newly
formed particles.
The role of organic vapors in NPF differs significantly according
to the volatility, which can span over 10 orders of magnitude (
10
).
The formation and survival of newly formed particles are respon-
sive to only a small fraction of organic vapors, which have (extremely)
low volatility and thus are capable of clustering with themselves or
sulfuric acid (
11
,
12
), and more readily condense onto the smallest
particles and favor their survival from scavenging loss (
13
–
15
).
Although observational evidence has suggested the existence of such
low-volatility organic vapors (
15
), their identity and sources have
been a puzzle for many years. Very recently, the autoxidation of
peroxy radicals (RO
2
), involving a few steps of intramolecular H
migration and subsequent O
2
addition (
16
), has been found as the
most efficient pathway of forming these low-volatility vapors (
17
).
Chemically, these vapors are highly oxygenated and therefore are
also widely referred to as highly oxygenated organic molecules
(HOMs) (
18
).
Nitrogen oxides (NO
x
), mainly emitted by anthropogenic activities
nowadays, are key players in atmospheric chemistry through their
reactions with other radicals (
19
). Their role in regulating atmospheric
oxidants is well established (
20
,
21
), with a direct impact on volatile
organic compound (VOC) oxidation processes and consequently
on the formation of condensable organic vapors. NO
x
has been
found to significantly suppress NPF from monoterpene oxidation
(
22
,
23
), although the cause was only speculated, lacking direct
observations on a molecular level. As HOMs have been known as
key precursors in NPF in multiple studies, it is foreseeable that
investigating the influence of NO
x
on them can help understand the
details about this “NO
x
suppression of particle formation.” Two
recent papers have addressed the role of NO
x
on atmospheric au-
toxidation, suggesting that reduced NO
x
concentrations will make
autoxidation increasingly more important in the future (
24
), although
the HOM formation rates from increased autoxidation may be
counteracted by a concurrent decrease in oxidant concentrations
(
25
). However, while these studies have addressed an overall “bulk”
HOM formation potential, NO
x
will affect not only the total HOM
yield but also their composition and, thereby, their physical properties.
Currently, our understanding of the effect of NO
x
on particle
formation can be improved from two aspects. First, the changes
caused by NO
x
on the chemical composition and bulk volatility of
HOMs need to be understood based on direct measurement on a
molecular level; second, the response of particle formation and
growth to those changes in HOMs needs to be investigated in detail.
We conducted well-controlled NPF experiments using the CLOUD
(Cosmics Leaving Outdoor Droplets) chamber equipped with a col-
lection of state-of-the-art instruments. The comprehensive mea-
surements allowed for obtaining important details of the NPF, from
formation of low-volatility vapors to particle nucleation and further
growth. After adding NO
x
at levels up to only a few parts per billion
by volume (ppbv), we observed substantial changes in both the
growth rates (GRs) of new particles and HOM composition. We
performed detailed analysis on HOM volatility based on their thermal
desorption temperature and found that NO
x
led to a significant in-
crease of HOM volatilities, which, in turn, could be quantitatively
connected to the suppression of particle GRs in a size-dependent
manner.
RESULTS
We performed a set of experiments in the CLOUD chamber at
CERN to investigate the effect of NO
x
on particle formation via
modifying the HOM composition. A typical experiment started with
an injection of ozone and monoterpenes without any NO
x
. A mix-
ture of
-pinene and
-3-carene with 2:1 volume mixing ratio
was used as VOC precursors to better resemble the monoterpene
profile in a boreal forest station [SMEAR II (Station for Measuring
Ecosystem-Atmosphere Relations)] in southern Finland (
26
). The
ultraviolet (UV) system was kept on throughout the experiment which
produces hydroxyl radicals (OH) by photolyzing O
3
(see Materials
and Methods), in addition to those OH from ozonolysis of mono-
terpenes. These two sources together resulted in a steady-state OH
concentration of around 10
6
cm
−3
. Similar to previous CLOUD
experiments (
12
), we started a typical experiment with adding
monoterpene and ozone with zero ions in the chamber (referred to
as neutral condition) and a relatively weak NPF occurred. We then
turned off the high voltage [referred to as galactic cosmic ray (GCR)
condition] and allowed the ions to trigger a stronger NPF that is
distinguishable from the weaker one (see Fig. 1B). After the nucle-
ation rate stabilized and particles grew to a few tens of nanometers,
we injected NO into the chamber, which was oxidized mostly to
NO
2
by O
3
(NO:NO
2
about 1%) and a small fraction further to NO
3
(NO
3
:NO
x
about 0.007%). As the NPF became progressively weaker
when NO
x
level increased, it is impossible to separate the subsequent
weaker NPF case from the former stronger one. Therefore, when
increasing the NO
x
level, we also removed all ions for roughly 15 min
(by turning on the high voltage) to quench the former nucleation,
which resulted in a clear “gap” between the NPF cases (see Fig. 1B).
The change of the HOM composition in both gas and particle phases
as well as the particle dynamics were measured at three different
NO
x
concentration levels. Experiments with similar procedure were
conducted with different monoterpene and SO
2
concentrations, except
for experiment 1748, in which the “NPF gaps” were not inserted
between NPF events, causing later events to be undistinguishable
(see table S1). Other detailed information about the chamber operation
and experimental conditions can be found in Materials and Methods.
NPF at different NO
x
levels
We show in Fig. 1 one example of the resulting data (experiment
1752, see table S1), demonstrating the influence of NO
x
on the HOM
formation and NPF.
A stepwise increase in the NO
x
concentration
caused an evident change in the HOM composition, featured by a
large increase of the HOM monomer (4 ≤ carbon number ≤ 10)
concentration and a simultaneous decrease of the HOM dimer
(10 < carbon number ≤ 20) concentration at higher NO
x
concentrations
(Fig. 1A). The monoterpene concentration did not change notably
during the addition of NO
x
, so the amount of monoterpenes available
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for chemical reactions was roughly constant throughout the ex
-
periment. Some changes in the concentrations of oxidants were
observed, but these changes were relatively small and cannot explain
the observed major change in the HOM composition.
New particles were being formed continuously throughout the
course of the experiment, where stronger bursts of new particles were
observed for GCR conditions (see Supplementary Materials). We show
in Fig. 1B that separated NPF events were triggered at different NO
x
levels. We characterize these NPF events by their particle formation
rate at 1.7 nm (
J
1.7
) and GRs in different size ranges (see the Supple-
mentary Materials). As shown in our previous work, the nucleation
in these experiments was driven by biogenic vapors (independent of
H
2
SO
4
), and the large reduction of
J
1.7
at higher NO
x
levels (Fig. 1C)
is a result of the decreased HOM dimer concentration (
11
).
We calculated the GRs of newly formed particles for different
size ranges according to their appearance time into these sizes (see
the Supplementary Materials). We found that the baseline GRs,
measured at the zero NO
x
condition, were 8.1 ± 4.5, 12.2 ± 4.7,
20.2 ± 3.7, 22.0 ± 0.9, 14.1 ± 0.6, and 10.6 ± 0.2 nm/hour in the size
ranges of 1.3 to 2.3, 1.9 to 3.5, 3.5 to 7, 7 to 20, 20 to 30, and >30 nm,
respectively. Size-segregated GRs after adding NO
x
were also calculated
and normalized to these baseline values (Fig. 1D). We found that
the GRs at different size ranges were reduced by different degrees:
The suppression was most pronounced for the smallest particles and
increasingly weaker for larger ones, eventually becoming almost
negligible for particles larger than 30 nm in diameter. These findings
clearly indicate that the effect of NO
x
cannot be thought of simply
as an overall suppression on the full course of NPF, since otherwise,
the GR at each size interval should have changed in the same way.
Instead, the results suggest a more complicated change in the vola-
tility distribution of condensable vapors.
We list size-segregated particle GRs determined for all experiments
in table S1 and plot the normalized GRs in fig. S1. Experiments 1749
to 1752 were conducted with a high level of monoterpenes, and the
strongest NPF events were observed in these experiments—the events
were still distinguishable even when moderate-level NO
x
was injected.
However, reliable determination of particle GRs is challenging for
experiments with lower monoterpene concentrations, e.g., exper-
iments 1753 to 1755, when the NPF events were much weaker. The
presence of H
2
SO
4
led to less pronounced reduction of GRs, as the
contribution of H
2
SO
4
to particle growth was almost unaffected by
NO
x
. This can be seen by comparing experiments with similar
monoterpene concentration but different H
2
SO
4
concentration, e.g.,
experiments 1749 and 1752. We also noticed that there are some
likely increase of
GR
7-20 nm
and
GR
20-30 nm
along with the increase of
NO
x
when H
2
SO
4
is present (e.g., experiments 1749 and 1750;
fig. S1). This indicates that H
2
SO
4
may interact with HOMs on the
surface of big particles, leading to an enhancement of HOM con-
densation. However, since the increase of GRs is not prominent
(around 20% maximum) and is within the uncertainty range, it is
difficult to fully validate this interpretation. For accuracy reasons, we
use experiment 1752 as the best example to show the effect of NO
x
,
but overall, the size-dependent suppression on particle growth is evident
in all experiments as long as the GRs can be well determined.
HOM composition modified by NO
x
We next investigate molecular-level changes in the HOM composition
between conditions with and without NO
x
, measured with a chemical
ionization atmospheric-pressure-interface time-of-flight mass spec-
trometer (CI-APi-TOF, see Supplementary Materials). Changes in
the HOM composition were observed immediately after NO
x
was
injected and were sensitive to the change of NO
x
concentration
(fig. S2). Here, we show the changes in HOM composition when
1.9 ppbv NO
x
was added in comparison to that without NO
x
. This
condition is chosen as it better represents the typical NO
x
level
(about 1.5 ppbv) and also best resembles the HOM composition
observed in a boreal forest station (SMEAR II) (fig. S2). To better
describe the behavior of HOMs, in addition to the division of HOM
monomers (marked with a subscript “mono”) and dimers (subscript
“di”), we further group them according to the number of contained
nitrogen atoms (0, 1, or 2), which are marked with C
x
H
y
O
z
, C
x
H
y
O
z
N,
and C
x
H
y
O
z
N
2
, respectively.
Before the injection of NO
x
, the HOMs formed in our experiment
were mostly C
x
H
y
O
z
_mono
(78.9%) and C
x
H
y
O
z
_di
(19.4%) compounds
with a tiny fraction (1.7%) of residual C
x
H
y
O
z
N
_mono
compounds
Fig. 1. Effect of NO
x
addition on the formation and growth of particles.
(
A
) Time
series of monoterpenes (C
10
H
16
), NO
x
, and HOM concentration. (
B
) Particle size
distribution showing the four different NPF events detected under different NO
x
conditions (0, 0.7, 1.9, and 4.5 ppbv). The appearance time of each particle size is
marked by white dots, based on which we further determined the size-segregated
GRs. (
C
) Temporal change of the nucleation rate at 1.7
nm (
J
1.7
) as well as the total
loss rate (red solid line), which includes both the wall loss rate (red dashed line) and
the condensation sink. (
D
) Normalized GRs at different size ranges. GRs at each
specific size range are normalized to that measured under the zero NO
x
condition,
and the ratios represent the suppression by NO
x
. It should be noted that such
suppression degrees are only valid for this specific condition and will vary in other
experiments (see fig. S1 and table S1).
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left from the previous experiment (Fig. 2, A and C). The presence
of 1.9 ppbv NO
x
resulted in the formation of organic nitrates
(Fig. 2, B and D), including C
x
H
y
O
z
N
_mono
(25.4%), C
x
H
y
O
z
N
2_mono
(3.0%), C
x
H
y
O
z
N
_di
(3.6%), and C
x
H
y
O
z
N
2_di
(0.5%). Meanwhile,
C
x
H
y
O
z
_mono
and C
x
H
y
O
z
_di
decreased to 60.7 and 6.7%, respectively.
The evolution of these species in the full course of the experiment
can be seen in fig. S3.
The HOM formation is a result of several complicated reactions,
in which the reactions between NO
x
and RO
2
play an important role
(
19
,
27
). We are not aiming to determine the exact contributions of
all reaction pathways here, so instead, we summarize below the most
important aspects of HOM formation and provide the supporting
observational evidence in the Supplementary Materials. First, we
found that the presence of NO
x
had a small impact on the overall
oxidative capacity in our experiments. Comparing conditions of
1.9 ppbv NO
x
to zero NO
x
, ozone and OH concentration decreased
by about 3 and 10%, respectively. Some NO
3
radicals were also
formed, as indicated by the presence of C
x
H
y
O
z
N
1-2_di
compounds
(see the Supplementary Materials). Second, the reactions between
NO and RO
2
were the main drivers of the changes in the HOM
composition, i.e., the reduction of C
x
H
y
O
z
_di
and the formation of
different C
x
H
y
O
z
N
_mono
. However, a similar effect via the reaction
between acylperoxy radical and NO
2
was also observed. Last, we did
not observe HOMs containing sulfur, suggesting that SO
2
and
H
2
SO
4
were not directly involved in the HOM formation in the gas
phase. The aforementioned main HOM formation pathways and
the respective fingerprint molecules can be found in table S2.
In addition to the gas-phase HOMs, we also measured the particle-
phase HOMs using the filter inlet for gases and aerosols (FIGAERO)
coupled to an iodide-based chemical ionization time-of-flight mass
spectrometer (see Supplementary Materials). The changes in the
particle-phase HOM composition were generally similar to that of
the gas-phase HOMs, featured by the increase of all types of organic
nitrates and the decrease of non-nitrate HOMs, especially dimers
(C
x
H
y
O
z
_di
) (fig. S2). The simultaneous change of HOM composition
in both gas and particle phases is a strong evidence that the particle
formation is directly affected by condensation of gas-phase HOMs.
Change of
HOM volatility distribution by NO
x
We finally estimate how the altered HOM composition changes the
HOM volatility, a key parameter that governs HOM condensation
and, therefore, connects the HOM chemistry with the particle growth
behavior. We first investigated the HOM volatilities according to
their thermal-desorption temperature (
T
max
, see the Supplementary
Materials). Figure 3A shows the thermograms of three representative
dimer compounds at different NO
x
levels, i.e., C
19
H
28
O
9
(400.17 Th),
C
20
H
31
O
8
N (413.20 Th), and C
20
H
32
O
11
N
2
(476.20 Th), representing
C
x
H
y
O
z
_di
, C
x
H
y
O
z
N
_di
, and C
x
H
y
O
z
N
2_di
compounds. Consistent
with former observations of HOMs in the gas phase, along with the
increase of NO
x
, C
19
H
28
O
9
decreases in contrast to the increase of
C
20
H
31
O
8
N and C
20
H
32
O
11
N
2
.
Although C
20
H
32
O
11
N
2
has a higher molecular weight and a
larger oxygen-to-carbon ratio (
O:C
) than C
19
H
28
O
9
, it desorbs at a
lower temperature, suggesting a higher volatility. Although the
T
max
of HOM dimers shows a weak dependence on the molecular weight
(Fig. 3B), the large discrepancy of
T
max
between different types
suggests that the molecular weight is not the most crucial parameter
for their volatility. We found that
T
max
is strongly correlated with
the effective
O:C
(
O:C
eff
) regardless of the HOM dimer type (Fig. 3C),
indicating that
O:C
eff
can be a good reference to their volatility.
Here, the
O:C
eff
is calculated based on the directly measured carbon
and oxygen numbers but subtracting two oxygen atoms for each
A
CD
%
×
3
B
Fig. 2. Gas-phase HOMs under zero and 1.9 ppbv NO
x
conditions measured by CI-APi-TOF in the CLOUD chamber.
(
A
and
B
) The spectra of HOMs colored by their
types. The pie charts give the fractional contribution of different types of HOMs. (
C
and
D
) Mass defect plots showing HOM composition under the two conditions. The
x
axis is the exact mass of HOMs, and the
y
axis is the mass defect. The color of circles denotes the type of HOMs, and their size is proportional to the logarithm of the count
rate. Each straight line represents a group of compounds with the same number of carbon, hydrogen, and nitrogen but different numbers of oxygen atoms. The line style
is the same as that used for the annotation frame.
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nitrogen atom. The use of
O:C
eff
can be justified by the volatility
dependence on the functional groups: It is suggested that the alcohol
(-OH) and nitrate (-ONO
2
) groups, contributing the same to
O:C
eff
,
reduce the volatility by a comparable amount (
28
). The strong
correlation between
T
max
and
O:C
eff
was derived from the measurement
of HOM dimers, as the observed
T
max
of HOM monomers often
suffer from influences by the thermal decomposition of oligomeric
compounds (
29
), which can be clearly seen in fig. S4. However, the
fundamental assumption that the volatility is affected by functional
groups should hold for monomers as well. Therefore, the relation-
ship between
T
max
and volatility of monomers is expected to follow
the same behavior. While we conclude that the influence of molecular
weight on HOM volatility is minor when comparing different
HOMs with similar carbon numbers, it becomes important for
molecules containing very different numbers of carbon atoms, such
as a HOM monomer versus a HOM dimer.
In our previous work, we parameterized the HOM volatility to
the apparent
O:C
(
14
), which is equal to the
O:C
eff
for HOMs not
containing nitrogen atoms. Here, we show that the same parame
-
terization can be extended to other types of HOMs by simply re-
placing the apparent
O:C
with the
O:C
eff
. The volatility of all types of
HOMs in this study is thus estimated as log
10
C
*
= (0.672 −
O:C
eff
)/
0.078 and log
10
C
*
= (0.209 −
O:C
eff
)/0.052 for HOM monomers and
dimers, respectively.
After applying the volatility parameterization to all HOMs, we
can obtain the overall HOM volatility distribution by grouping
them into volatility bins. For simplicity, we compare the volatility
distribution at zero NO
x
and 1.9 ppbv NO
x
(Fig. 4A). In both cases,
the volatility spans a large range from extremely low-volatility
organic compounds (ELVOCs,
C
*
≤ 10
–4.5
g m
−3
or roughly
equivalent to
N
*
≤ 5 × 10
4
cm
−3
assuming an average molar mass of
300 Da), through low-volatility organic compounds (LVOCs,
10
–4.5
<
C
*
≤ 10
–0.5
g m
−3
; 5 × 10
4
<
N
*
≤ 5 × 10
8
cm
−3
), and on to
semivolatile organic compounds (SVOCs, 10
–0.5
<
C
*
≤ 10
2.5
g
m
−3
or 5 × 10
8
<
N
*
≤ 5 × 10
11
cm
−3
). Adding NO
x
considerably
shifts the overall distribution toward a higher volatility. As shown
in fig. S5, the fractional decrease of ELVOCs is mostly due to the
suppressed C
x
H
y
O
z
_di
formation by NO
x
, which is slightly compensated
by the formation of C
x
H
y
O
z
N
1-2_di
. The increase of LVOCs and
SVOCs mostly results from the formation of C
x
H
y
O
z
N
1-2_mono
. Simply
put, NO
x
suppresses dimer formation and replaces dimers with or-
ganic nitrate monomers.
Since the particle GR depends approximately linearly on the
concentration of condensable vapors, the ratio of particle GRs at
different NO
x
conditions shown in Fig. 1 should be reflective of the
corresponding HOM concentration ratios. Figure 4B shows the
cumulative HOM concentrations for the two NO
x
conditions together
with their ratio, which increases from ~0.2 for the nonvolatile
HOMs (
C
*
≤ 10
−15
g m
−3
or
N
*
≪
1 cm
−3
) close to unity when
counting all LVOCs (
C
*
< 10
–0.5
g m
−3
or 5 × 10
8
cm
−3
). This
volatility measurement, relying on the identity and
T
max
of HOMs,
provides the confirmation of our initial hypothesis that the change
in HOM composition caused by NO
x
is indeed able to explain the
observed size-dependent GRs: The abundance of the least volatile
vapors is substantially reduced, thus affecting the growth of the
smallest particles, while the total concentration of vapors able to
condense onto particles with diameters of a few tens of nanometers
remains similar.
The tight connection between HOM volatility and particle for
-
mation is also supported by the correlogram between the cumulative
HOM concentration and particle formation and GRs using data
from all experiments listed in table S1. As shown in fig. S6, the
correlation coefficient for
GR
1.9-3.5 nm
is at maximum for HOMs
with
C
*
≤ 10
–7.5
g m
−3
(
N
*
≤ 5 × 10
1
cm
−3
), and quickly decreases
if HOMs of higher volatility are included, indicating that these
higher-volatility HOMs do not contribute to the particle growth in
this size range. Such quick decline of the correlation coefficient for
the
GR
20-30 nm
only occurs when HOMs of
C
*
≥ 10
–2.5
g m
−3
(
N
*
≥ 5 × 10
6
cm
−3
) are counted, showing a less strict volatility
requirement for growing 20- to 30-nm particles owing to the
diminished curvature effect. Moreover, the correlations for
J
1.7
and
GR
1.9-3.5 nm
show very similar patterns, suggesting that the formation
and growth of particles at these size ranges are likely led by the same
vapors or at least by vapors with nearly fixed relative yields.
DISCUSSION
In summary, using the CERN CLOUD facilities, we performed
dedicated experiments to investigate the role of NO
x
in the particle
growth under conditions that mimic the atmosphere in a boreal forest
AB
C
Fig. 3. Thermal desorption of particle-phase HOM dimers measured with the FIGAERO.
(
A
) The thermogram of three example molecules under different NO
x
condi-
tions. Different line styles represent different NO
x
conditions. The
T
max
is defined as the temperature at which the signal intensity reaches the maximum. (
B
) Correlation
between
T
max
and mass-to-charge ratio for all HOM dimers. (
C
) Correlation between
T
max
and the effective O:C for all HOM dimers. The size of the circles in (B) and (C) is
linearly proportional to the signal intensity of the desorption thermogram.
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with slight influence by human activities. The comprehensive mea-
surements of both the particle precursors vapors (HOMs) and the
particle dynamics allow us to evaluate the influence of NO
x
at all
stages of gas-to-particle conversion—from the oxidation of VOC
forming HOMs to the particle nucleation and the subsequent particle
growth over various size ranges. Our results show a generally con-
sistent picture with the few recent studies that NPF is suppressed by
NO
x
due to the change of HOM chemistry (
22
,
23
). However, on the
basis of the detailed analysis on particle dynamics, we reveal that the
suppression effect of NO
x
on particle formation is rather nonuniform
and size dependent. Furthermore, we elucidate that the size-dependent
suppression on particle growth can be quantitatively connected to
the increased HOM bulk volatility as a result of changes in the
HOM chemistry and composition.
In our experiments, we also observed suppressed particle formation
rates (
J
1.7
) and attributed this to the reduced HOM dimer formation
(
11
). However, this effect becomes significantly weaker when also
NH
3
and H
2
SO
4
are present (
11
). This means that the suppression
effect of NO
x
on particle nucleation, reported in previous studies
(
22
,
23
) and in this work, cannot be directly applied to the atmo-
sphere where NH
3
or even stronger bases together with H
2
SO
4
tend
to drive the nucleation.
However, unlike the particle nucleation, the suppression of
particle growth driven by HOMs is directly relevant to the ambient
atmosphere. After adding NO
x
, we observed much stronger influence
(suppression) on particle growth of small particles (~2 nm), while
that on large particles (>30 nm) was negligible. This observation has
important implications. First, as smaller particles are more easily
scavenged by preexisting particles, the attenuated GR of small
particles significantly reduces the survival probability of the newly
formed particles and thus causes a reduction of the concentration of
CCN-size particles, as seen in our experiments. Second, it also
provides a plausible explanation for the laboratory observations showing
that NO
x
has a smaller effect on the yield regarding secondary
organic aerosol (SOA) formation than on NPF (
22
,
23
). In addition,
our results show that NO is more effective than NO
2
in changing
the HOM composition and volatility. This indicates that, besides
the commonly used term “VOC/NO
x
,” the NO:NO
2
ratio is another
crucial parameter in understanding the influence of NO
x
on SOA
formation.
From a more general perspective, our results contribute to the
understanding on the climatic effects of NO
x
. It is well known that
NO
x
can form inorganic nitrate aerosol via HNO
3
condensation and
reactive uptake of N
2
O
5
(
30
) and contribute to the formation of
organic nitrate aerosol via the NO
3
-initiated oxidation (
31
). The
nitrate constituents are able to modify several aerosol properties,
including their hygroscopicity (
32
) and light absorption capability
(
33
). Our results suggest that in monoterpene-rich environments, such
as forested areas, NO
x
can significantly reduce the CCN formation
and thereby influence cloud properties. Our experimental insights, as
presented above, can also help improve the modeling of such effects.
MATERIALS AND
METHODS
The CLOUD facility
The CLOUD chamber is a stainless steel cylinder with a volume of
ca. 26.1 m
3
, located at CERN, Geneva, Switzerland. The most im-
portant feature of this chamber is its ultracleanliness, which allows
one to study the NPF phenomenon under carefully controlled and
atmospherically relevant conditions, i.e., with precursors of similar
concentrations to those in the atmosphere. Dedicated efforts are
made to ensure a low contamination level in the chamber; besides
the electropolished inner surfaces of the chamber, vigorous rinsing
with ultrapure water at 373 K is done before each campaign, and
ultraclean synthetic air produced by mixing cryogenic liquid nitrogen
and oxygen is used throughout the experiments. The background
total VOC concentration is at sub-ppbv level, and the total condensable
vapor concentration is at sub-pptv (parts per trillion by volume)
level. Ion concentrations in the chamber can be controlled with a
high-voltage clearing field. By turning on the high-voltage field
(20 kV m
−1
), all ions and charged particles are removed; we refer to
this as the neutral condition state. When the high voltage is switched
off, ions are produced by the GCR in the chamber; we refer to this
as the GCR condition.
To mimic the photochemistry caused by sunlight in the atmo-
sphere, a UV light system was used. The system consists of three
light sources that cover different regions of the UV and visible spectrum.
A krypton fluoride excimer UV laser (3 W,
= 248 nm) is used to
produce OH via O
3
photolysis. Two UV light-emitting diodes
(LEDs; 2 × 16.5 W,
= 370 to 390 nm) are used to photolyze
NO
2
into NO.
In addition, four Hamamatsu Xenon arc lamps
(4 × 200 W,
= 250 to 580 nm) are used to provide broad range UV
light and bring the overall UV spectrum closer to atmospheric levels.
The xenon arc light and the UV laser are fed vertically through the
top of the chamber by optical fibers, while the UV LEDs shine into
the chamber horizontally from opposite sides in the middle plane.
All gases are injected through a dedicated inlet system from the
bottom of the chamber. In order to improve the homogeneity of gas
mixing inside the big chamber volume, two mixing fans are mounted
on the top and the bottom of the chamber.
Fig. 4. Volatility distribution of gas-phase HOMs under zero and 1.9 ppbv
NO
x
conditions.
(
A
) The summed HOM concentrations of each bin. (
B
) The cumu-
lative HOM concentrations. Red and blue markers denote HOM concentrations under
zero and 1.9 ppbv NO
x
, respectively. The black dots give the ratio of cumulative
concentrations of [HOM]
NOx
:[HOM]
w/o NOx
.
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Experimental design
We conducted a set of experiments for studying the effect of NO
x
on HOM production and NPF at constant temperature (278 K) and
relative humidity (38%). We kept the injection rate of ozone constant
throughout the experiments, thereby maintaining an ozone volume
mixing ratio of ca. 40 ppbv. We started a typical experiment with
adding monoterpenes under neutral conditions. The monoterpene
precursors were a mix of
-pinene and
-3-carene, the two most
abundant monoterpenes at the Hyytiälä station with an initial
mixing ratio of 2:1 (
26
); these compounds are structurally similar,
both having one endocyclic double bond on the six-carbon ring.
Once the HOM concentration reached steady state and the nucle-
ation rate also stabilized, we turned off the high voltage and allowed
the ion concentration to build up, which is referred to in CLOUD
experiments as the GCR condition. The ions triggered a stronger
particle nucleation that can be easily distinguished from the previous,
weaker one under neutral conditions. After the nucleation rate at
the GCR condition reached the plateau and the particles grew to a
few tens of nanometers, we started injecting NO into the chamber,
most of which is quickly oxidized to NO
2
by O
3
; a small fraction of
the NO
2
can be further oxidized to NO
3
. The injection rate of NO
was equivalent to a photolysis rate
J
NO2
of 1.5 × 10
−4
s
−1
, about one
order of magnitude lower than that at the Hyytiälä station in spring
daytime (median value of 2.7 × 10
−3
s
−1
). As a result, the final
NO:NO
2
was at ca. 1%, lower than in the atmosphere at our reference
station. After all types of HOMs reached steady state and a stable
nucleation rate was obtained, the NO
x
level was further increased.
In most of the experiments, we increased NO
x
in three stages: ~0.7,
1.9, and 4.5 ppbv NO
x
. Because each step of increasing NO
x
led to a
weaker NPF event, we activated the clearing field for about 15 min
to quench the previous NPF event, thereby separating the new
nucleation event from the previous one for better characterization.
We refer the aforementioned experimental sequence as one complete
run, which was repeated with various initial monoterpene concen-
trations coupled with different initial SO
2
concentrations. Throughout
the run, the UV light system was kept on to avoid any change in
NPF associated to a varied UV irradiation. The main experimental
variables are listed in table S1.
We monitored the NPF events with a variety of instruments (see
the Supplementary Materials) and calculated size-resolved particle
GRs according to their appearance time (see the Supplementary
Materials and fig.S6). In addition, we deployed two chemical ion-
ization mass spectrometers (CIMS) to extend observations of NPF
into a molecular level: a nitrate-based CIMS, also known as CI-APi-
TOF, for measuring sulfuric acid and more oxidized HOMs in the
gas phase and an iodide-based CIMS equipped with FIGAERO focusing
on detecting oxidation products of VOCs in the particle phase (see
the Supplementary Materials). We estimated the HOM volatility from
their thermal desorption temperature (
T
max
) together with the vola-
tility parameterization developed by Tröstl and co-
wo
rkers (
14
).
SUPPLEMENTARY MATERIALS
Supplementary material for this article is available at http://advances.sciencemag.org/cgi/
content/full/6/22/eaay4945/DC1
REFERENCES AND NOTES
1.
J.
Merikanto, D.
V.
Spracklen, G.
W.
Mann, S.
J.
Pickering, K.
S.
Carslaw, Impact
of
nucleation on
global CCN.
Atmos. Chem. Phys.
9
, 8601–8616 (2009).
2.
O.
Boucher, D.
Randall, P.
Artaxo, C.
Bretherton, G.
Feingold, P.
Forster, V.-M.
Kerminen,
Y.
Kondo, H.
Liao, U.
Lohmann, P.
Rasch, S.
K. Satheesh, S.
Sherwood, B.
Stevens, X.
Y. Z
hang,
Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth
Assessment Report of the Intergovernmental Panel on Climate Change
(Cambridge Univ.
Press, 2013), pp.
571–657.
3.
M.
Kulmala, J.
Kontkanen, H.
Junninen, K.
Lehtipalo, H.
E.
Manninen, T.
Nieminen,
T.
Petäjä, M.
Sipilä, S.
Schobesberger, P.
Rantala, A.
Franchin, T.
Jokinen, E.
Järvinen,
M.
Äijälä, J.
Kangasluoma, J.
Hakala, P.
P.
Aalto, P.
Paasonen, J.
Mikkilä, J.
Vanhanen,
J.
Aalto, H.
Hakola, U.
Makkonen, T.
Ruuskanen, R.
L.
Mauldin
III, J.
Duplissy, H.
Vehkamäki,
J.
Bäck, A.
Kortelainen, I.
Riipinen, T.
Kurtén, M.
V.
Johnston, J.
N.
Smith, M.
Ehn,
T.
F.
Mentel, K.
E.
J.
Lehtinen, A.
Laaksonen, V.-M.
Kerminen, D.
R.
Worsnop, Direct
observations of
atmospheric aerosol nucleation.
Science
339
, 943–946 (2013).
4.
H.
Vehkamäki, I.
Riipinen, Thermodynamics and
kinetics of
atmospheric aerosol particle
formation
and
growth.
Chem. Soc. Rev.
41
, 5160–5173 (2012).
5.
P.
H.
Mcmurry, M.
Fink, H.
Sakurai, M.
R.
Stolzenburg, R.
L.
Mauldin
III, J.
Smith, F.
Eisele,
K.
Moore, S.
Sjostedt, D.
Tanner, L.
G.
Huey, J.
B.
Nowak, E.
Edgerton, D.
Voisin, A criterion
for
new particle formation in
the
sulfur–rich Atlanta atmosphere.
J.
Geophys. Res. Atmos.
110
, 2935–2948 (2005).
6.
F.
Riccobono, S.
Schobesberger, C.
E.
Scott, J.
Dommen, I.
K.
Ortega, L.
Rondo, J.
Almeida,
A.
Amorim, F.
Bianchi, M.
Breitenlechner, A.
David, A.
Downard, E.
M.
Dunne, J.
Duplissy,
S.
Ehrhart, R.
C.
Flagan, A.
Franchin, A.
Hansel, H.
Junninen, M.
Kajos, H.
Keskinen, A.
Kupc,
A.
Kürten, A.
N.
Kvashin, A.
Laaksonen, K.
Lehtipalo, V.
Makhmutov, S.
Mathot,
T.
Nieminen, A.
Onnela, T.
Petäjä, A.
P.
Praplan, F.
D.
Santos, S.
Schallhart, J.
H.
Seinfeld,
M.
Sipilä, D.
V.
Spracklen, Y.
Stozhkov, F.
Stratmann, A.
Tomé, G.
Tsagkogeorgas,
P.
Vaattovaara, Y.
Viisanen, A.
Vrtala, P.
E.
Wagner, E.
Weingartner, H.
Wex, D.
Wimmer,
K.
S.
Carslaw, J.
Curtius, N.
M.
Donahue, J.
Kirkby, M.
Kulmala, D.
R.
Worsnop,
U.
Baltensperger, Oxidation products of
biogenic emissions contribute to
nucleation
of
atmospheric particles.
Science
344
, 717–721 (2014).
7.
R.
Zhang, I.
Suh, J.
Zhao, D.
Zhang, E.
C.
Fortner, X.
Tie, L.
T.
Molina, M.
J.
Molina,
Atmospheric new particle formation enhanced by organic acids.
Science
304
, 1487–1490
(2004).
8.
I.
Riipinen, J.
R.
Pierce, T.
Yli-Juuti, T.
Nieminen, S.
Häkkinen, M.
Ehn, H.
Junninen,
K.
Lehtipalo, T.
Petäjä, J.
Slowik, R.
Chang, N.
C.
Shantz, J.
Abbatt, W.
R.
Leaitch,
V.-M.
Kerminen, D.-R.
Worsnop, S.
N.
Pandis, N.
M.
Donahue, M.
Kulmala, Organic
condensation: A
vital link connecting aerosol formation to
cloud condensation nuclei
(CCN) concentrations.
Atmos. Chem. Phys.
11
, 3865–3878 (2011).
9.
J.
N.
Smith, M.
J.
Dunn, T.
M.
Van
Reken,
K.
Iida, M.
R.
Stolzenburg, P.
H.
McMurry,
L.
G.
Huey, Chemical composition of
atmospheric nanoparticles formed from
nucleation
in
Tecamac, Mexico: Evidence for
an
important role for
organic species in
nanoparticle
growth.
Geophys. Res. Lett.
35
, 228–236 (2008).
10.
N.
M.
Donahue, J.
H.
Kroll, S.
N.
Pandis, A.
L.
Robinson, A two-dimensional volatility basis
set—Part 2: Diagnostics of
organic-aerosol evolution.
Atmos. Chem. Phys.
12
, 615–634
(2012).
11.
K.
Lehtipalo, C.
Yan, L.
Dada, F.
Bianchi, M.
Xiao, R.
Wagner, D.
Stolzenburg, L.
R.
Ahonen,
A.
Amorim, A.
Baccarini, P.
S.
Bauer, B.
Baumgartner, A.
Bergen, A.-K.
Bernhammer,
M.
Breitenlechner, S.
Brilke, A.
Buchholz, S.
B.
Mazon, D.
Chen, X.
Chen, A.
Dias,
J.
Dommen, D.
C.
Draper, J.
Duplissy, M.
Ehn, H.
Finkenzeller, L.
Fischer, C.
Frege, C.
Fuchs,
O.
Garmash, H.
Gordon, J.
Hakala, X.
He, L.
Heikkinen, M.
Heinritzi, J.
C.
Helm, V.
Hofbauer,
C.
R.
Hoyle, T.
Jokinen, J.
Kangasluoma, V.-M.
Kerminen, C.
Kim, J.
Kirkby, J.
Kontkanen,
A.
Kürten, M.
J.
Lawler, H.
Mai, S.
Mathot, R.
L.
Mauldin
III, U.
Molteni, L.
Nichman, W.
Nie,
T.
Nieminen, A.
Ojdanic, A.
Onnela, M.
Passananti, T.
Petäjä, F.
Piel, V.
Pospisilova,
L.
L.
J.
Quéléver, M.
P.
Rissanen, C.
Rose, N.
Sarnela, S.
Schallhart, S.
Schuchmann,
K.
Sengupta, M.
Simon, M.
Sipilä, C.
Tauber, A.
Tomé, J.
Tröstl, O.
Väisänen, A.
L.
Vogel,
R.
Volkamer, A.
C.
Wagner, M.
Wang, L.
Weitz, D.
Wimmer, P.
Ye, A.
Ylisirniö, Q.
Zha,
K.
S.
Carslaw, J.
Curtius, N.
M.
Donahue, R.
C.
Flagan, A.
Hansel, I.
Riipinen, A.
Virtanen,
P.
M.
Winkler, U.
Baltensperger, M.
Kulmala, D.
R.
Worsnop, Multicomponent new particle
formation from
sulfuric acid, ammonia, and
biogenic vapors.
Sci. Adv.
4
, eaau5363 (2018).
12.
J.
Kirkby, J.
Duplissy, K.
Sengupta, C.
Frege, H.
Gordon, C.
Williamson, M.
Heinritzi,
M.
Simon, C.
Yan, J.
Almeida, J.
Tröstl, T.
Nieminen, I.
K.
Ortega, R.
Wagner, A.
Adamov,
A.
Amorim, A.-K.
Bernhammer, F.
Bianchi, M.
Breitenlechner, S.
Brilke, X.
Chen, J.
Craven,
A.
Dias, S.
Ehrhart, R.
C.
Flagan, A.
Franchin, C.
Fuchs, R.
Guida, J.
Hakala, C.
R.
Hoyle,
T.
Jokinen, H.
Junninen, J.
Kangasluoma, J.
Kim, M.
Krapf, A.
Kürten, A.
Laaksonen,
K.
Lehtipalo, V.
Makhmutov, S.
Mathot, U.
Molteni, A.
Onnela, O.
Peräkylä, F.
Piel, T.
Petäjä,
A.
P.
Praplan, K.
Pringle, A.
Rap, N.
A.
D.
Richards, I.
Riipinen, M.
P.
Rissanen, L.
Rondo,
N.
Sarnela, S.
Schobesberger, C.
E.
Scott, J.
H.
Seinfeld, M.
Sipilä, G.
Steiner, Y.
Stozhkov,
F.
Stratmann, A.
Tomé, A.
Virtanen, A.
L.
Vogel, A.
C.
Wagner, P.
E.
Wagner, E.
Weingartner,
D.
Wimmer, P.
M.
Winkler, P.
Ye, X.
Zhang, A.
Hansel, J.
Dommen, N.
M.
Donahue,
D.
R.
Worsnop, U.
Baltensperger, M.
Kulmala, K.
S.
Carslaw, J.
Curtius, Ion-induced
nucleation of
pure biogenic particles.
Nature
533
, 521–526 (2016).
13.
N.
M.
Donahue, I.
K.
Ortega, W.
Chuang, I.
Riipinen, F.
Riccobono, S.
Schobesberger,
J.
Dommen, U.
Baltensperger, M.
Kulmala, D.
R.
Worsnop, H.
Vehkamaki, How do organic
vapors contribute to
new-particle formation?
Faraday Discuss.
165
, 91–104 (2013).
14.
J.
Tröstl, W.
K.
Chuang, H.
Gordon, M.
Heinritzi, C.
Yan, U.
Molteni, L.
Ahlm, C.
Frege,
F.
Bianchi, R.
Wagner, M.
Simon, K.
Lehtipalo, C.
Williamson, J.
S.
Craven, J.
Duplissy,
on May 27, 2020
http://advances.sciencemag.org/
Downloaded from
Yan
et al
.,
Sci. Adv.
2020;
6
: eaay4945 27 May 2020
SCIENCE ADVANCES
|
RESEARCH ARTICLE
8 of 9
A.
Adamov, J.
Almeida, A.-K.
Bernhammer, M.
Breitenlechner, S.
Brilke, A.
Dias, S.
Ehrhart,
R.
C.
Flagan, A.
Franchin, C.
Fuchs, R.
Guida, M.
Gysel, A.
Hansel, C.
R.
Hoyle, T.
Jokinen,
H.
Junninen, J.
Kangasluoma, H.
Keskinen, J.
Kim, M.
Krapf, A.
Kürten, A.
Laaksonen,
M.
Lawler, M.
Leiminger, S.
Mathot, O.
Möhler, T.
Nieminen, A.
Onnela, T.
Petäjä, F.
M.
Piel,
P.
Miettinen, M.
P.
Rissanen, L.
Rondo, N.
Sarnela, S.
Schobesberger, K.
Sengupta,
M.
Sipilä, J.
N.
Smith, G.
Steiner, A.
Tomè, A.
Virtanen, A.
C.
Wagner, E.
Weingartner,
D.
Wimmer, P.
M.
Winkler, P.
Ye, K.
S.
Carslaw, J.
Curtius, J.
Dommen, J.
Kirkby, M.
Kulmala,
I.
Riipinen, D.
R.
Worsnop, N.
M.
Donahue, U.
Baltensperger, The role of
low-volatility
organic compounds in
initial particle growth in
the
atmosphere.
Nature
533
, 527–531
(2016).
15.
I.
Riipinen, T.
Yli-Juuti, J.
R.
Pierce, T.
Petäjä, D.
R.
Worsnop, M.
Kulmala, N.
M.
Donahue,
The contribution of
organics to
atmospheric nanoparticle growth.
Nat. Geosci.
5
, 453–458
(2012).
16.
J.
D.
Crounse, L.
B.
Nielsen, S.
Jørgensen, H.
G.
Kjaergaard, P.
O.
Wennberg, Autoxidation
of
organic compounds in
the
atmosphere.
J.
Phys. Chem. Lett.
4
, 3513–3520 (2013).
17.
M.
Ehn, J.
A.
Thornton, E.
Kleist, M.
Sipilä, H.
Junninen, I.
Pullinen, M.
Springer, F.
Rubach,
R.
Tillmann, B.
Lee, F.
Lopez-Hilfiker, S.
Andres, I.-H.
Acir, M.
Rissanen, T.
Jokinen,
S.
Schobesberger, J.
Kangasluoma, J.
Kontkanen, T.
Nieminen, T.
Kurtén, L.
B.
Nielsen,
S.
Jørgensen, H.
G.
Kjaergaard, M.
Canagaratna, M.
D.
Maso, T.
Berndt, T.
Petäjä,
A.
Wahner, V.-M.
Kerminen, M.
Kulmala, D.
R.
Worsnop, J.
Wildt, T.
F.
Mentel, A large
source of
low-volatility secondary organic aerosol.
Nature
506
, 476–479 (2014).
18.
M.
Ehn, E.
Kleist, H.
Junninen, T.
Petäjä, G.
Lönn, S.
Schobesberger, M.
Dal
Maso,
A.
Trimborn, M.
Kulmala, D.
R.
Worsnop, A.
Wahner, J.
Wildt, T.
F.
Mentel, Gas phase
formation of
extremely oxidized pinene reaction products in
chamber and
ambient air.
Atmos. Chem. Phys.
12
, 5113–5127 (2012).
19.
J.
J.
Orlando, G.
S.
Tyndall, Laboratory studies of
organic peroxy radical chemistry:
An
overview with
emphasis on
recent issues of
atmospheric significance.
Chem. Soc. Rev.
41
, 6294–6317 (2012).
20.
J.
H. Seinfeld, S.
N. Pandis,
Atmospheric Chemistry and Physics: From Air Pollution to Climate
Change
(John Wiley & Sons, 2012).
21.
B.
J. Finlayson-Pitts, J.
N. Pitts Jr.,
Atmospheric Chemistry: Fundamentals and Experimental
Techniques
(Wiley, 1986).
22.
J.
Wildt, T.
F.
Mentel, A.
Kiendler-Scharr, T.
Hoffmann, S.
Andres, M.
Ehn, E.
Kleist,
P.
Müsgen, F.
Rohrer, Y.
Rudich, M.
Springer, R.
Tillmann, A.
Wahner, Suppression of
new
particle formation from
monoterpene oxidation by NO
x
.
Atmos. Chem. Phys.
14
,
2789–2804 (2014).
23.
D.
Zhao, S.
H.
Schmitt, M.
Wang, I.-H.
Acir, R.
Tillmann, Z.
Tan, A.
Novelli, H.
Fuchs,
I.
Pullinen, R.
Wegener, F.
Rohrer, J.
Wildt, A.
Kiendler-Scharr, A.
Wahner, T.
F.
Mentel,
Effects of
NO
x
and
SO
2
on
the
secondary organic aerosol formation from
photooxidation
of
-pinene and
limonene.
Atmos. Chem. Phys.
18
, 1611–1628 (2018).
24.
E.
Praske, R.
V.
Otkjær, J.
D.
Crounse, J.
C.
Hethcox, B.
M.
Stoltz, H.
G.
Kjaergaard,
P.
O.
Wennberg, Atmospheric autoxidation is increasingly important in
urban
and
suburban North America.
Proc. Natl. Acad. Sci. U.S.A.
115
, 64–69 (2018).
2
5.
H.
O.
Pye, E.
L.
D’Ambro, B.
H.
Lee, S.
Schobesberger, M.
Takeuchi, Y.
Zhao, F.
Lopez-Hilfiker,
J.
Liu, J.
E.
Shilling, J.
Xing, R.
Mathur, A.
M.
Middlebrook, J.
Liao, A.
Welti, M.
Graus,
C.
Warneke, J.
A.
de
Gouw,
J.
S.
Holloway, T.
B.
Ryerson, I.
B.
Pollack, J.
A.
Thornton,
Anthropogenic enhancements to
production of
highly oxygenated molecules
from
autoxidation.
Proc. Natl. Acad. Sci. U.S.A.
116
, 6641–6646 (2019).
26.
J.
Rinne, H.
Hakola, T.
Laurila, Ü.
Rannik, Canopy scale monoterpene emissions of
Pinus
sylvestris
dominated forests.
Atmos. Environ.
34
, 1099–1107 (2000).
27.
F.
Bianchi, T.
Kurtén, M.
Riva, C.
Mohr, M.
P.
Rissanen, P.
Roldin, T.
Berndt, J.
D.
Crounse,
P.
O.
Wennberg, T.
F.
Mentel, J.
Wildt, H.
Junninen, T.
Jokinen, M.
Kulmala, D.
R.
Worsnop,
J.
A.
Thornton, N.
Donahue, H.
G.
Kjaergaard, M.
Ehn, Highly oxygenated organic
molecules (HOM) from
gas-phase autoxidation involving peroxy radicals: A
key
contributor to
atmospheric aerosol.
Chem. Rev.
119
, 3472–3509 (2019).
28.
W.
K.
Chuang, N.
M.
Donahue, A two-dimensional volatility basis set—Part 3: Prognostic
modeling
and
NO
x
dependence.
Atmos. Chem. Phys.
16
, 123–134 (2016).
29.
H.
Stark, R.
L.
N.
Yatavelli, S.
L.
Thompson, H.
Kang, J.
E.
Krechmer, J.
R.
Kimmel, B.
B.
Palm,
W.
Hu, P.
L.
Hayes, D.
A.
Day, P.
Campuzano-Jost, M.
R.
Canagaratna, J.
T.
Jayne,
D.
R.
Worsnop, J.
L.
Jimenez, Impact of
thermal decomposition on
thermal desorption
instruments: Advantage of
thermogram analysis for
quantifying volatility distributions
of
organic species.
Environ. Sci. Technol.
51
, 8491–8500 (2017).
30.
H.
Wang, K.
Lu, X.
Chen, Q.
Zhu, Q.
Chen, S.
Guo, M.
Jiang, X.
Li, D.
Shang, Z.
Tan, Y.
Wu,
Z.
Wu, Q.
Zou, Y.
Zheng, L.
Zeng, T.
Zhu, M.
Hu, Y.
Zhang, High N
2
O
5
concentrations
observed in
urban Beijing: Implications of
a
large nitrate formation pathway.
Environ. Sci.
Technol. Lett.
4
, 416–420 (2017).
31.
A.
Kiendler-Scharr, A.
A.
Mensah, E.
Friese, D.
Topping, E.
Nemitz, A.
S.
H.
Prevot, M.
Äijälä,
J.
Allan, F.
Canonaco, M.
Canagaratna, S.
Carbone, M.
Crippa, M.
Dall
Osto,
D.
A.
Day,
P.
De
Carlo,
C.
F.
Di
Marco,
H.
Elbern, A.
Eriksson, E.
Freney, L.
Hao, H.
Herrmann,
L.
Hildebrandt, R.
Hillamo, J.
L.
Jimenez, A.
Laaksonen, G.
McFiggans, C.
Mohr, C.
O’Dowd,
R.
Otjes, J.
Ovadnevaite, S.
N.
Pandis, L.
Poulain, P.
Schlag, K.
Sellegri, E.
Swietlicki, P.
Tiitta,
A.
Vermeulen, A.
Wahner, D.
Worsnop, H.-C.
Wu, Ubiquity of
organic nitrates
from
nighttime chemistry in
the
European submicron aerosol.
Geophys. Res. Lett.
43
,
7735–7744 (2016).
32.
M.
H.
Barley, D.
Topping, D.
Lowe, S.
Utembe, G.
McFiggans, The sensitivity of
secondary
organic aerosol (SOA) component partitioning to
the
predictions of
component
properties—Part 3: Investigation of
condensed compounds generated by a
near-explicit
model of
VOC oxidation.
Atmos. Chem. Phys.
11
, 13145–13159 (2011).
33.
T.
Moise, J.
M.
Flores, Y.
Rudich, Optical properties of
secondary organic aerosols and
their
changes by chemical processes.
Chem. Rev.
115
, 4400–4439 (2015).
34.
T.
Jokinen, T.
Berndt, R.
Makkonen, V.-M.
Kerminen, H.
Junninen, P.
Paasonen,
F.
Stratmann, H.
Herrmann, A.
B.
Guenther, D.
R.
Worsnop, M.
Kulmala, M.
Ehn, M.
Sipilä,
Production of
extremely low volatile organic compounds from
biogenic emissions:
Measured yields and
atmospheric implications.
Proc. Natl. Acad. Sci. U.S.A.
112
,
7123–7128 (2015).
35.
T.
Jokinen, M.
Sipilä, H.
Junninen, M.
Ehn, G.
Lönn, J.
Hakala, T.
Petäjä, R.
L.
Mauldin
III,
M.
Kulmala, D.
R.
Worsnop, Atmospheric sulphuric acid and
neutral cluster
measurements using CI-APi-TOF.
Atmos. Chem. Phys.
12
, 4117–4125 (2012).
36.
H.
Junninen, M.
Ehn, T.
Petäjä, L.
Luosujärvi, T.
Kotiaho, R.
Kostiainen, U.
Rohner, M.
Gonin,
K.
Fuhrer, M.
Kulmala, D.
R.
Worsnop, A high-resolution mass spectrometer to
measure
atmospheric ion composition.
Atmos. Meas. Tech.
3
, 1039–1053 (2010).
37.
M.
Heinritzi, M.
Simon, G.
Steiner, A.
C.
Wagner, A.
Kürten, A.
Hansel, J.
Curtius,
Characterization of
the
mass-dependent transmission efficiency of
a
CIMS.
Atmos. Meas.
Tech.
9
, 1449–1460 (2016).
38.
N.
Hyttinen, O.
Kupiainen-Määttä, M.
P.
Rissanen, M.
Muuronen, M.
Ehn, T.
Kurtén,
Modeling the
charging of
highly oxidized cyclohexene ozonolysis products using
nitrate-based chemical ionization.
J.
Phys. Chem. A
119
, 6339–6345 (2015).
39.
T.
Berndt, S.
Richters, T.
Jokinen, N.
Hyttinen, T.
Kurtén, R.
V.
Otkjær, H.
G.
Kjaergaard,
F.
Stratmann, H.
Herrmann, M.
Sipilä, M.
Kulmala, M.
Ehn, Hydroxyl radical-induced
formation of
highly oxidized organic compounds.
Nat. Commun.
7
, 13677 (2016).
40.
F.
D.
Lopez-Hilfiker, C.
Mohr, M.
Ehn, F.
Rubach, E.
Kleist, J.
Wildt, T.
F.
Mentel, A.
Lutz,
M.
Hallquist, D.
Worsnop, J.
A.
Thornton, A novel method for
online analysis of
gas
and
particle composition: Description and
evaluation of
a
Filter Inlet for
Gases
and
AEROsols (FIGAERO).
Atmos. Meas. Tech.
7
, 983–1001 (2014).
41.
D.
Stolzenburg, L.
Fischer, A.
L.
Vogel, M.
Heinritzi, M.
Schervish, M.
Simon, A.
C.
Wagner,
L.
Dada, L.
R.
Ahonen, A.
Amorim, A.
Baccarini, P.
S.
Bauer, B.
Baumgartner, A.
Bergen,
F.
Bianchi, M.
Breitenlechner, S.
Brilke, S.
Buenrostro
Mazon,
D.
Chen, A.
Dias, D.
C.
Draper,
J.
Duplissy, I.
El
Haddad,
H.
Finkenzeller, C.
Frege, C.
Fuchs, O.
Garmash, H.
Gordon, X.
He,
J.
Helm, V.
Hofbauer, C.
R.
Hoyle, C.
Kim, J.
Kirkby, J.
Kontkanen, A.
Kürten, J.
Lampilahti,
M.
Lawler, K.
Lehtipalo, M.
Leiminger, H.
Mai, S.
Mathot, B.
Mentler, U.
Molteni, W.
Nie,
T.
Nieminen, J.
B.
Nowak, A.
Ojdanic, A.
Onnela, M.
Passananti, T.
Petäjä, L.
L.
J.
Quéléver,
M.
P.
Rissanen, N.
Sarnela, S.
Schallhart, C.
Tauber, A.
Tomé, R.
Wagner, M.
Wang, L.
Weitz,
D.
Wimmer, M.
Xiao, C.
Yan, P.
Ye, Q.
Zha, U.
Baltensperger, J.
Curtius, J.
Dommen,
R.
C.
Flagan, M.
Kulmala, J.
N.
Smith, D.
R.
Worsnop, A.
Hansel, N.
M.
Donahue,
P.
M.
Winkler, Rapid growth of
organic aerosol nanoparticles over a
wide tropospheric
temperature range.
Proc. Natl. Acad. Sci.
115
, 9122–9127 (2018).
42.
M.
Breitenlechner, L.
Fischer, M.
Hainer, M.
Heinritzi, J.
Curtius, A.
Hansel, PTR3:
An
instrument for
studying the
lifecycle of
reactive organic carbon in
the
atmosphere.
Anal. Chem.
89
, 5824–5831 (2017).
43.
J.
Vanhanen, J.
Mikkilä, K.
Lehtipalo, M.
Sipilä, H.
E.
Manninen, E.
Siivola, T.
Petäjä,
M.
Kulmala, Particle size magnifier for
nano-CN detection.
Aero. Sci. Technol.
45
, 533–542
(2011).
44.
K.
Lehtipalo, J.
Leppa, J.
Kontkanen, J.
Kangasluoma, A.
Franchin, D.
Wimnner,
S.
Schobesberger, H.
Junninen, T.
Petaja, M.
Sipila, J.
Mikkila, J.
Vanhanen, D.
R.
Worsnop,
M.
Kulmala, Methods for
determining particle size distribution and
growth rates between
1 and
3
nm using the
Particle Size Magnifier.
Boreal Environ. Res.
19
, 215–236 (2014).
45.
D.
Stolzenburg, G.
Steiner, P.
M.
Winkler, A DMA-train for
precision measurement
of
sub-10
nm aerosol dynamics.
Atmos. Meas. Tech.
10
, 1639–1651 (2017).
46.
S.
Mirme, A.
Mirme, The mathematical principles and
design of
the
NAIS—A spectrometer
for
the
measurement of
cluster ion and
nanometer aerosol size distributions.
Atmos. Meas. Tech.
6
, 1061–1071 (2013).
47.
J.
Kangasluoma, A.
Samodurov, M.
Attoui, A.
Franchin, H.
Junninen, F.
Korhonen,
T.
Kurtén, H.
Vehkamäki, M.
Sipilä, K.
Lehtipalo, D.
R.
Worsnop, T.
Petäjä, M.
Kulmala,
Heterogeneous nucleation onto ions and
neutralized ions: Insights into sign-preference.
J.
Phys. Chem. C
120
, 7444–7450 (2016).
48.
K.
Lehtipalo, L.
Rondo, J.
Kontkanen, S.
Schobesberger, T.
Jokinen, N.
Sarnela, A.
Kürten,
S.
Ehrhart, A.
Franchin, T.
Nieminen, F.
Riccobono, M.
Sipilä, T.
Yli-Juuti, J.
Duplissy,
A.
Adamov, L.
Ahlm, J.
Almeida, A.
Amorim, F.
Bianchi, M.
Breitenlechner, J.
Dommen,
A.
J.
Downard, E.
M.
Dunne, R.
C.
Flagan, R.
Guida, J.
Hakala, A.
Hansel, W.
Jud, J.
K
angasluoma,
V.-M.
Kerminen, H.
Keskinen, J.
Kim, J.
Kirkby, A.
Kupc, O.
Kupiainen-Määttä, A.
Laaksonen,
M.
J.
Lawler, M.
Leiminger, S.
Mathot, T.
Olenius, I.
K.
Ortega, A.
Onnela, T.
Petäjä,
A.
Praplan, M.
P.
Rissanen, T.
Ruuskanen, F.
D.
Santos, S.
Schallhart, R.
Schnitzhofer,
M.
Simon, J.
N.
Smith, J.
Tröstl, G.
Tsagkogeorgas, A.
Tomé, P.
Vaattovaara, H.
Vehkamäki,
A.
E.
Vrtala, P.
E.
Wagner, C.
Williamson, D.
Wimmer, P.
M.
Winkler, A.
Virtanen,
on May 27, 2020
http://advances.sciencemag.org/
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