scholarly journals Production of highly oxygenated organic molecules (HOMs) from trace contaminants during isoprene oxidation

2018 ◽  
Vol 11 (8) ◽  
pp. 4763-4773 ◽  
Author(s):  
Anne-Kathrin Bernhammer ◽  
Lukas Fischer ◽  
Bernhard Mentler ◽  
Martin Heinritzi ◽  
Mario Simon ◽  
...  
Keyword(s):  
Organic Molecules ◽  
Nuclear Research ◽  
Proton Transfer Reaction ◽  
Reaction Chamber ◽  
Diels Alder ◽  
Cloud Chamber ◽  
Atmospheric Conditions ◽  
European Organization ◽  
Main Fragment ◽  
Isoprene Oxidation

Abstract. During nucleation studies from pure isoprene oxidation in the CLOUD chamber at the European Organization for Nuclear Research (CERN) we observed unexpected ion signals at m∕z = 137.133 (C10H17+) and m∕z = 81.070 (C6H9+) with the recently developed proton-transfer-reaction time-of-flight (PTR3-TOF) mass spectrometer instrument. The mass-to-charge ratios of these ion signals typically correspond to protonated monoterpenes and their main fragment. We identified two origins of these signals: first secondary association reactions of protonated isoprene with isoprene within the PTR3-TOF reaction chamber and secondly [4+2] cycloaddition (Diels–Alder) of isoprene inside the gas bottle which presumably forms the favored monoterpenes limonene and sylvestrene, as known from literature. Under our PTR3-TOF conditions used in 2016 an amount (relative to isoprene) of 2 % is formed within the PTR3-TOF reaction chamber and 1 % is already present in the gas bottle. The presence of unwanted cycloaddition products in the CLOUD chamber impacts the nucleation studies by creating ozonolysis products as the corresponding monoterpenes and is responsible for the majority of the observed highly oxygenated organic molecules (HOMs), which in turn leads to a significant overestimation of both the nucleation rate and the growth rate. In order to study new particle formation (NPF) from pure isoprene oxidation under relevant atmospheric conditions, it is important to improve and assure the quality and purity of the precursor isoprene. This was successfully achieved by cryogenically trapping lower-volatility compounds such as monoterpenes before isoprene was introduced into the CLOUD chamber.

scholarly journals Production of highly oxygenated organic molecules (HOMs) from trace contaminants during isoprene oxidation

2018 ◽  
Author(s):  
Anne-Kathrin Bernhammer ◽  
Lukas Fischer ◽  
Bernhard Mentler ◽  
Martin Heinritzi ◽  
Mario Simon ◽  
...  
Keyword(s):  
Reaction Time ◽  
Organic Molecules ◽  
Transfer Reaction ◽  
Proton Transfer Reaction ◽  
Reaction Chamber ◽  
Diels Alder ◽  
Cloud Chamber ◽  
Secondary Association ◽  
Main Fragment ◽  
Isoprene Oxidation

Abstract. During nucleation studies from pure isoprene oxidation in the CLOUD chamber at CERN we observed unexpected ion signals at m/z = 137.133 (C10H17+) and m/z = 81.070 (C6H9+) with the recently developed proton transfer reaction time-of-flight mass spectrometer (PTR3‑TOF) instrument. The mass-to-charge ratios of these ion signals typically correspond to protonated monoterpenes and their main fragment. We identified two origins of these signals: First secondary association reactions of protonated isoprene with isoprene within the PTR3 reaction chamber and secondly [4+2] cycloaddition (Diels-Alder) of isoprene inside the gas bottle which presumably forms the favoured monoterpenes limonene and sylvestrene, as known from literature. Under our PTR3 conditions used in 2016 an amount (relative to isoprene) of 2 % is formed within the PTR3 reaction chamber and 1 % is already present in the gas bottle. The presence of unwanted cycloaddition products in the CLOUD chamber impacts the nucleation studies by creating ozonolysis products as corresponding monoterpenes, and is responsible for the majority of the observed highly oxygenated organic molecules (HOMs). In order to study NPF from pure isoprene oxidation under atmospheric relevant conditions, it is important to improve and assure the quality and purity of the precursor isoprene. This was successfully achieved by cryogenically trapping lower volatility compounds such as monoterpenes before isoprene was introduced into the CLOUD chamber.

Highly oxygenated organic molecules (HOM) formation in the isoprene oxidation by NO3 radical

2021 ◽  
Author(s):  
Defeng Zhao ◽  
Iida Pullinen ◽  
Hendrik Fuchs ◽  
Stephanie Schrade ◽  
Rongrong Wu ◽  
...  
Keyword(s):  
Organic Molecules ◽  
Closed Shell ◽  
Open Shell ◽  
Reaction Chamber ◽  
Peroxy Radicals ◽  
Night Time ◽  
Time Profiles ◽  
No3 Radical ◽  
Isoprene Oxidation ◽  
First And Second Generation

<p><strong>       </strong>Highly oxygenated organic molecules (HOM) are found to play an important role in the formation and growth of secondary organic aerosol (SOA). SOA is an important type of aerosol with significant impact on air quality and climate. Compared to the oxidation of volatile organic compounds by O<sub>3</sub> and OH, HOM formation in the oxidation by NO<sub>3</sub> radical, an important oxidant at night-time and dawn, has received less attention. In this study, HOM formation in the reaction of isoprene with NO<sub>3</sub> was investigated in the SAPHIR chamber (Simulation of Atmospheric PHotochemistry In a large Reaction chamber). A large number of HOM including monomers (C<sub>5</sub>), dimers (C<sub>10</sub>), and trimers (C<sub>15</sub>), both closed-shell compounds and open-shell peroxy radicals, were detected. HOM were classified into various series according to their formula, which included monomers containing one or more N atoms, dimers containing 1-4 N atoms, and trimers containing 3-5 N atoms. Tentative formation pathways of HOM were proposed reflecting known NO<sub>3</sub> and RO<sub>2</sub> chemistry in the literature under consideration of the autoxidation via peroxy pathways and peroxy-alkoxy pathways. Further mechanistic constraints were given by the time profiles of HOM after sequential isoprene addition which enabled to differentiate first- and second-generation products. Total HOM molar yield was estimated, which suggests that HOM may contribute a significant fraction to SOA yield in the reaction of isoprene with NO<sub>3</sub>.</p>

scholarly journals Characterisation of organic contaminants in the CLOUD chamber at CERN

2014 ◽  
Vol 7 (7) ◽  
pp. 2159-2168 ◽  
Author(s):  
R. Schnitzhofer ◽  
A. Metzger ◽  
M. Breitenlechner ◽  
W. Jud ◽  
M. Heinritzi ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Organic Contaminants ◽  
Nuclear Research ◽  
Proton Transfer Reaction ◽  
Galactic Cosmic Rays ◽  
Nucleation And Growth ◽  
Dead Volume ◽  
Background Concentration ◽  
Strongly Correlated ◽  
European Organization

Abstract. The CLOUD experiment (Cosmics Leaving OUtdoor Droplets) investigates the nucleation of new particles and how this process is influenced by galactic cosmic rays in an electropolished, stainless-steel environmental chamber at CERN (European Organization for Nuclear Research). Since volatile organic compounds (VOCs) can act as precursor gases for nucleation and growth of particles, great efforts have been made to keep their unwanted background levels as low as possible and to quantify them. In order to be able to measure a great set of VOCs simultaneously in the low parts per trillion (pptv) range, proton-transfer-reaction mass spectrometry (PTR-MS) was used. Initially the total VOC background concentration strongly correlated with ozone in the chamber and ranged from 0.1 to 7 parts per billion (ppbv). Plastic used as sealing material in the ozone generator was found to be a major VOC source. Especially oxygen-containing VOCs were generated together with ozone. These parts were replaced by stainless steel after CLOUD3, which strongly reduced the total VOC background. An additional ozone-induced VOC source is surface-assisted reactions at the electropolished stainless steel walls. The change in relative humidity (RH) from very dry to humid conditions increases background VOCs released from the chamber walls. This effect is especially pronounced when the RH is increased for the first time in a campaign. Also the dead volume of inlet tubes for trace gases that were not continuously flushed was found to be a short but strong VOC contamination source. For lower ozone levels (below 100 ppbv) the total VOC contamination was usually below 1 ppbv and therewith considerably cleaner than a comparable Teflon chamber. On average about 75% of the total VOCs come from only five exact masses (tentatively assigned as formaldehyde, acetaldehyde, acetone, formic acid, and acetic acid), which have a rather high vapour pressure and are therefore not important for nucleation and growth of particles.

scholarly journals Enhanced growth rate of atmospheric particles from sulfuric acid

2020 ◽  
Vol 20 (12) ◽  
pp. 7359-7372 ◽  
Author(s):  
Dominik Stolzenburg ◽  
Mario Simon ◽  
Ananth Ranjithkumar ◽  
Andreas Kürten ◽  
Katrianne Lehtipalo ◽  
...  
Keyword(s):  
Growth Rate ◽  
Sulfuric Acid ◽  
Growth Rates ◽  
Particle Number ◽  
Nuclear Research ◽  
Initial Growth ◽  
Atmospheric Conditions ◽  
European Organization ◽  
Dipole Interactions ◽  
The Impact

Abstract. In the present-day atmosphere, sulfuric acid is the most important vapour for aerosol particle formation and initial growth. However, the growth rates of nanoparticles (<10 nm) from sulfuric acid remain poorly measured. Therefore, the effect of stabilizing bases, the contribution of ions and the impact of attractive forces on molecular collisions are under debate. Here, we present precise growth rate measurements of uncharged sulfuric acid particles from 1.8 to 10 nm, performed under atmospheric conditions in the CERN (European Organization for Nuclear Research) CLOUD chamber. Our results show that the evaporation of sulfuric acid particles above 2 nm is negligible, and growth proceeds kinetically even at low ammonia concentrations. The experimental growth rates exceed the hard-sphere kinetic limit for the condensation of sulfuric acid. We demonstrate that this results from van der Waals forces between the vapour molecules and particles and disentangle it from charge–dipole interactions. The magnitude of the enhancement depends on the assumed particle hydration and collision kinetics but is increasingly important at smaller sizes, resulting in a steep rise in the observed growth rates with decreasing size. Including the experimental results in a global model, we find that the enhanced growth rate of sulfuric acid particles increases the predicted particle number concentrations in the upper free troposphere by more than 50 %.

scholarly journals Characterisation of organic contaminants in the CLOUD chamber at CERN

2013 ◽  
Vol 6 (4) ◽  
pp. 7709-7734 ◽  
Author(s):  
R. Schnitzhofer ◽  
A. Metzger ◽  
M. Breitenlechner ◽  
W. Jud ◽  
M. Heinritzi ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Organic Contaminants ◽  
Nuclear Research ◽  
Proton Transfer Reaction ◽  
Galactic Cosmic Rays ◽  
Nucleation And Growth ◽  
Dead Volume ◽  
Background Concentration ◽  
European Organization ◽  
Polished Stainless Steel

Abstract. The CLOUD experiment (Cosmics Leaving OUtdoor Droplets) investigates the nucleation of new particles and how this process is influenced by galactic cosmic rays in an electro-polished, stainless-steel environmental chamber at CERN (European Organization for Nuclear Research). Since volatile organic compounds (VOCs) can act as precursor gases for nucleation and growth of particles, great efforts have been made to keep their unwanted background levels as low as possible and to quantify them. In order to be able to measure a great set of VOCs simultaneously in the low parts per trillion (pptv) range, proton-transfer-reaction mass spectrometry (PTR-MS) was used. Initially the total VOC background concentration strongly correlated with ozone in the chamber and ranged from 0.1 to 7 parts per billion (ppbv). Plastic used as sealing material in the ozone generator was found to be a major VOC source. Especially oxygen-containing VOCs were generated together with ozone. These parts were replaced by stainless steel from CLOUD4 (June 2011) on, which strongly reduced the total VOC background. An additional ozone induced VOC source is surface assisted reactions at the electropolished stainless steel walls. The change in relative humidity (RH) from very dry to humid conditions increases background VOCs released from the chamber walls. This effect is especially pronounced when the RH is increased for the first time in a campaign. Also the dead volume of inlet tubes for trace gases that were not continuously flushed were found to be a short but strong VOC contamination source. For the later CLOUD campaigns lower ozone levels (below 100 ppbv) were used. During these conditions the total VOC contamination was usually below 1 ppbv and therewith considerably cleaner than a comparable Teflon chamber. On average more than 80% of the total VOCs are coming from only 5 exact masses (tentatively assigned as formaldehyde, acetaldehyde, acetone, formic acid, and acetic acid), which have a rather high vapour pressure and are therefore not important for nucleation and growth of particles.

scholarly journals Temperature uniformity in the CERN CLOUD chamber

2017 ◽  
Vol 10 (12) ◽  
pp. 5075-5088 ◽  
Author(s):  
António Dias ◽  
Sebastian Ehrhart ◽  
Alexander Vogel ◽  
Christina Williamson ◽  
João Almeida ◽  
...  
Keyword(s):  
Steady State ◽  
Air Temperature ◽  
Elevated Temperatures ◽  
Trace Gases ◽  
Vertical Direction ◽  
Cloud Chamber ◽  
Temperature Uniformity ◽  
Atmospheric Conditions ◽  
Cloud Droplets ◽  
Experimental Conditions

Abstract. The CLOUD (Cosmics Leaving OUtdoor Droplets) experiment at CERN (European Council for Nuclear Research) investigates the nucleation and growth of aerosol particles under atmospheric conditions and their activation into cloud droplets. A key feature of the CLOUD experiment is precise control of the experimental parameters. Temperature uniformity and stability in the chamber are important since many of the processes under study are sensitive to temperature and also to contaminants that can be released from the stainless steel walls by upward temperature fluctuations. The air enclosed within the 26 m3 CLOUD chamber is equipped with several arrays (strings) of high precision, fast-response thermometers to measure its temperature. Here we present a study of the air temperature uniformity inside the CLOUD chamber under various experimental conditions. Measurements were performed under calibration conditions and run conditions, which are distinguished by the flow rate of fresh air and trace gases entering the chamber at 20 and up to 210 L min−1, respectively. During steady-state calibration runs between −70 and +20 °C, the air temperature uniformity is better than ±0.06 °C in the radial direction and ±0.1 °C in the vertical direction. Larger non-uniformities are present during experimental runs, depending on the temperature control of the make-up air and trace gases (since some trace gases require elevated temperatures until injection into the chamber). The temperature stability is ±0.04 °C over periods of several hours during either calibration or steady-state run conditions. During rapid adiabatic expansions to activate cloud droplets and ice particles, the chamber walls are up to 10 °C warmer than the enclosed air. This results in temperature differences of ±1.5 °C in the vertical direction and ±1 °C in the horizontal direction, while the air returns to its equilibrium temperature with a time constant of about 200 s.

scholarly journals Large Hadron Collider as a Legal Phenomenon

Lex Russica ◽  
2019 ◽  
pp. 161-173 ◽  
Author(s):  
A. O. Chetverikov
Keyword(s):  
Large Hadron Collider ◽  
Legal Status ◽  
Hadron Collider ◽  
Nuclear Research ◽  
European Organization ◽  
History Of Development ◽  
Scientific Organizations ◽  
Legal Nature ◽  
History Of ◽  
Scientific Collaborations

   Сontinued. See: LEX RUSSICA. 2019. № 4. Pp. 151—169This paper is the first in Russia comprehensive theoretical and practical study of one of the world’s largest international scientific installations of the «megasience» class — the Large Hadron Collider (LHC) — from the standpoint of legal science.The author focuses on the unique legal status and legal nature of international scientific collaborations, with the help ofwhichscientistsfromdozensofcountries, including Russia, carry outresearchandmakescientificdiscoveries on the LHC. The paper considers and analyzed the following: the history of development, general principles of the LHC and the European organization for nuclear research (CERN), under the auspices of which its construction was carried out; the principles of the structure and functioning of international scientific collaborations around the LHC; the legal nature of their constituent documents as acts of soft law; the ratio of soft and hard law mechanisms in the regulation of international scientific collaborations around the LHC.The final section presents data and proposals on the use of the legal mechanisms studied in other countries and international organizations, including for the purpose of the construction of scientific installations of the «megasience» class under the auspices of the national scientific organizations of Russia and the Joint Institute for Nuclear Research in Dubna (Moscow region).

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