scholarly journals Estimation of secondary organic aerosol viscosity from explicit modeling of gas-phase oxidation of isoprene and <i>α</i>-pinene

2021 ◽  
Vol 21 (13) ◽  
pp. 10199-10213
Author(s):  
Tommaso Galeazzo ◽  
Richard Valorso ◽  
Ying Li ◽  
Marie Camredon ◽  
Bernard Aumont ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Relative Humidity ◽  
Gas Phase ◽  
Fine Particulate Matter ◽  
Bulk Diffusion ◽  
Accommodation Coefficient ◽  
Gas Phase Reactions ◽  
Chemical Modeling ◽  
High Molar Mass ◽  
Mass Accommodation Coefficient

Abstract. Secondary organic aerosols (SOA) are major components of atmospheric fine particulate matter, affecting climate and air quality. Mounting evidence exists that SOA can adopt glassy and viscous semisolid states, impacting formation and partitioning of SOA. In this study, we apply the GECKO-A (Generator of Explicit Chemistry and Kinetics of Organics in the Atmosphere) model to conduct explicit chemical modeling of isoprene photooxidation and α-pinene ozonolysis and their subsequent SOA formation. The detailed gas-phase chemical schemes from GECKO-A are implemented into a box model and coupled to our recently developed glass transition temperature parameterizations, allowing us to predict SOA viscosity. The effects of chemical composition, relative humidity, mass loadings and mass accommodation on particle viscosity are investigated in comparison with measurements of SOA viscosity. The simulated viscosity of isoprene SOA agrees well with viscosity measurements as a function of relative humidity, while the model underestimates viscosity of α-pinene SOA by a few orders of magnitude. This difference may be due to missing processes in the model, including autoxidation and particle-phase reactions, leading to the formation of high-molar-mass compounds that would increase particle viscosity. Additional simulations imply that kinetic limitations of bulk diffusion and reduction in mass accommodation coefficient may play a role in enhancing particle viscosity by suppressing condensation of semi-volatile compounds. The developed model is a useful tool for analysis and investigation of the interplay among gas-phase reactions, particle chemical composition and SOA phase state.

scholarly journals Estimation of Secondary Organic Aerosol Viscosity from Explicit Modeling of Gas-Phase Oxidation of Isoprene and α-pinene

2021 ◽  
Author(s):  
Tommaso Galeazzo ◽  
Richard Valorso ◽  
Ying Li ◽  
Marie Camredon ◽  
Bernard Aumont ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Relative Humidity ◽  
Gas Phase ◽  
Fine Particulate Matter ◽  
Bulk Diffusion ◽  
Accommodation Coefficient ◽  
Gas Phase Reactions ◽  
High Molar Mass ◽  
Chemical Mechanisms ◽  
Mass Accommodation Coefficient

Abstract. Secondary organic aerosols (SOA) are major components of atmospheric fine particulate matter, affecting climate and air quality. Mounting evidence exists that SOA can adopt glassy and viscous semisolid states, impacting formation and partitioning of SOA. In this study, we conduct explicit modeling of isoprene photooxidation and α-pinene ozonolysis and subsequent SOA formation using the GECKO-A (Generator of Explicit Chemistry and Kinetics of Organics in the Atmosphere) model. Our recently-developed parameterizations to predict glass transition temperature of organic compounds are implemented into a box model with explicit gas-phase chemical mechanisms to simulate viscosity of SOA. The effects of chemical composition, relative humidity, mass loadings and mass accommodation on particle viscosity are investigated in comparison with measurements of SOA viscosity. The simulated viscosity of isoprene SOA agrees well with viscosity measurements as a function of relative humidity, while the model underestimates viscosity of α-pinene SOA by a few orders of magnitude. This difference may be due to missing processes in the model including gas-phase dimerization and particle-phase reactions leading to the formation of high molar mass compounds that would increase particle viscosity. Additional simulations imply that kinetic limitations of bulk diffusion and reduction in mass accommodation coefficient may also play a role in enhancing particle viscosity by suppressing condensation of semi-volatile compounds. The developed model is a useful tool for analysis and investigation of the interplay among gas-phase reactions, particle chemical composition and SOA phase state.

scholarly journals Uptake of HNO<sub>3</sub> to deliquescent sea-salt particles

2002 ◽  
Vol 2 (3) ◽  
pp. 739-763 ◽  
Author(s):  
C. Guimbaud ◽  
F. Arens ◽  
L. Gutzwiller ◽  
H. W. Gäggeler ◽  
M. Ammann
Keyword(s):  
Gas Phase ◽  
Data Interpretation ◽  
Accommodation Coefficient ◽  
Sea Salt ◽  
Uptake Coefficient ◽  
Concentration Data ◽  
Sea Salt Aerosol ◽  
The North ◽  
Partial Pressures ◽  
Mass Accommodation Coefficient

Abstract. The uptake of HNO3 to deliquescent airborne sea-salt particles (RH = 55%, P = 760 torr, T = 300 K) at concentrations from 2 to 575 ppbv is measured in an aerosol flow tube using 13N as a tracer. Small particles (~ 70 nm diameter) are used in order to minimize the effect of diffusion in the gas phase on the mass transfer. Below 100 ppbv, an uptake coefficient (gupt) of 0.50 ± 0.20 is derived. At higher concentrations, the uptake coefficient decreases along with the consumption of aerosol chloride. Data interpretation is further supported by using the North American Aerosol Inorganics Model (AIM), which predicts the aqueous phase activities of ions and the gas-phase partial pressures of H2O, HNO3, and HCl at equilibrium for the NaCl/HNO3/H2O system. These simulations show that the low concentration data are obtained far from equilibrium, which implies that the uptake coefficient derived is equal to the mass accommodation coefficient under these conditions. The observed uptake coefficient can serve as input to modeling studies of atmospheric sea-salt aerosol chemistry. The main sea-salt aerosol burden in the marine atmosphere is represented by coarse mode particles (> 1 mm diameter). This implies that diffusion in the gas-phase is the limiting step to HNO3 uptake until the sea-salt has been completely processed.

scholarly journals Chemical composition of nanoparticles from α-pinene nucleation and the influence of isoprene and relative humidity at low temperature

2021 ◽  
Author(s):  
Lucía Caudillo ◽  
Birte Rörup ◽  
Martin Heinritzi ◽  
Guillaume Marie ◽  
Mario Simon ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Relative Humidity ◽  
Gas Phase ◽  
Particle Formation ◽  
Oxidation Products ◽  
Mixed System ◽  
Chemical Information ◽  
New Particle Formation ◽  
Detection Scheme ◽  
Wide Range

Abstract. New Particle Formation (NPF) from biogenic organic precursors is an important atmospheric process. One of the major species is α-pinene, which upon oxidation, can form a suite of products covering a wide range of volatilities. A fraction of the oxidation products is termed Highly Oxygenated Organic Molecules (HOM). These play a crucial role for nucleation and the formation of Secondary Organic Aerosol (SOA). However, measuring the composition of newly formed particles is challenging due to their very small mass. Here, we present results on the gas and particle phase chemical composition for a system where α-pinene was oxidized by ozone, and for a mixed system of α-pinene and isoprene, respectively. The measurements took place at the CERN Cosmics Leaving Outdoor Droplets (CLOUD) chamber at temperatures between −50 °C and −30 °C and at low and high relative humidity (20 % and 60 to 100 % RH). These conditions were chosen to simulate pure biogenic new particle formation in the upper free troposphere. The particle chemical composition was analyzed by the Thermal Desorption-Differential Mobility Analyzer (TD-DMA) coupled to a nitrate chemical ionization time-of-flight mass spectrometer. This instrument can be used for particle and gas phase measurements using the same ionization and detection scheme. Our measurements revealed the presence of C8-10 monomers and C18-20 dimers as the major compounds in the particles (diameter up to ~ 100 nm). Particularly, for the system with isoprene added, C5 (C5H10O5-7) and C15 compounds (C15H24O5-10) are detected. This observation is consistent with the previously observed formation of such compounds in the gas phase. However, although the C5 and C15 compounds do not easily nucleate, our measurements indicate that they can still contribute to the particle growth at free tropospheric conditions. For the experiments reported here, most likely isoprene might enhance growth at particle sizes larger than 15 nm. Besides the chemical information regarding the HOM formation for the α-pinene (plus isoprene) system, we report on the nucleation rates measured at 1.7 nm and found that the lower J1.7nm values compared with previous studies are very likely due to the higher α-pinene and ozone mixing ratios used in the present study

scholarly journals Gas-phase prebiotic chemistry in extraterrestrial environments

2009 ◽  
Vol 5 (H15) ◽  
pp. 682-683 ◽  
Author(s):  
Nadia Balucani
Keyword(s):  
Gas Phase ◽  
Gas Phase Reactions ◽  
Chemical Modeling ◽  
Elementary Reactions ◽  
Interstellar Clouds ◽  
Neutral Gas ◽  
Prebiotic Molecules ◽  
Complex Chemistry ◽  
Cometary Comae

AbstractA variety of molecular species up to complex polyatomic molecules/radicals have been identified in many extraterrestrial gaseous environments, including interstellar clouds, cometary comae and planetary atmospheres. Amongst the identified molecules/radicals, a large percentage are organic in nature and encompass also prebiotic molecules. Different types of microscopic processes are believed to be involved in their formation, including surface processes, ion- and radical- molecule reactions. A thorough characterization of such a complex chemistry relies on a multi-disciplinary approach, where the observations are complemented by accurate chemical modeling. Unfortunately, a literature survey reveals that only a small percentage of the elementary reactions considered in the available models have been characterized in laboratory experiments. In this contribution, a brief overview will be given of recent experimental techniques that have allowed us to reach a better description of neutral-neutral gas-phase reactions, which might be responsible for the formation of simple prebiotic molecules.

scholarly journals Uptake of HNO<sub>3</sub> to deliquescent sea-salt particles: a study using the short-lived radioactive isotope tracer <sup>13</sup>N

2002 ◽  
Vol 2 (4) ◽  
pp. 249-257 ◽  
Author(s):  
C. Guimbaud ◽  
F. Arens ◽  
L. Gutzwiller ◽  
H. W. Gäggeler ◽  
M. Ammann
Keyword(s):  
Gas Phase ◽  
Data Interpretation ◽  
Accommodation Coefficient ◽  
Sea Salt ◽  
Uptake Coefficient ◽  
Concentration Data ◽  
Isotope Tracer ◽  
Sea Salt Aerosol ◽  
The North ◽  
Mass Accommodation Coefficient

Abstract. The uptake of HNO3 to deliquescent airborne sea-salt particles (RH = 55%, P = 760 torr, T = 300 K) at concentrations from 2 to 575 ppbv is measured in an aerosol flow tube using 13N as a tracer. Small particles (<approx> 70 nm diameter) are used in order to minimize the effect of diffusion in the gas phase on the mass transfer. Below 100 ppbv, an uptake coefficient (gupt) of 0.50 ± 0.20 is derived. At higher concentrations, the uptake coefficient decreases along with the consumption of aerosol chloride. Data interpretation is further supported by using the North American Aerosol Inorganics Model (AIM), which predicts the aqueous phase activities of ions and the gas-phase partial pressures of H2O, HNO3, and HCl at equilibrium for the NaCl/HNO3/H2O system. These simulations show that the low concentration data are obtained far from equilibrium, which implies that the uptake coefficient derived is equal to the mass accommodation coefficient under these conditions. The observed uptake coefficient can serve as input to modeling studies of atmospheric sea-salt aerosol chemistry. The main sea-salt aerosol burden in the marine atmosphere is represented by coarse mode particles (> 1 µm diameter). This implies that diffusion in the gas-phase is the limiting step to HNO3 uptake until the sea-salt has been completely processed.

Gas-Phase Reactions

1981 ◽  
Author(s):  
Victor N. Kondratiev ◽  
Evgeniĭ E. Nikitin
Keyword(s):  
Gas Phase ◽  
Gas Phase Reactions

scholarly journals An Atmospheric Origin for HCN-Derived Polymers on Titan

Processes ◽  
2021 ◽  
Vol 9 (6) ◽  
pp. 965
Author(s):  
Zoé Perrin ◽  
Nathalie Carrasco ◽  
Audrey Chatain ◽  
Lora Jovanovic ◽  
Ludovic Vettier ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Gas Phase ◽  
Formation Process ◽  
Upper Atmosphere ◽  
Gas Mixture ◽  
Space Probe ◽  
Atmospheric Haze ◽  
Formation And Evolution ◽  
Haze Formation

Titan’s haze is strongly suspected to be an HCN-derived polymer, but despite the first in situ measurements by the ESA-Huygens space probe, its chemical composition and formation process remain largely unknown. To investigate this question, we simulated the atmospheric haze formation process, experimentally. We synthesized analogues of Titan’s haze, named Titan tholins, in an irradiated N2–CH4 gas mixture, mimicking Titan’s upper atmosphere chemistry. HCN was monitored in situ in the gas phase simultaneously with the formation and evolution of the haze particles. We show that HCN is produced as long as the particles are absent, and is then progressively consumed when the particles appear and grow. This work highlights HCN as an effective precursor of Titan’s haze and confirms the HCN-derived polymer nature of the haze.

Influence of Gas Mixing and Heating on Gas-Phase Reactions in GaN MOCVD Growth

2012 ◽  
Vol 1 (1) ◽  
pp. P46-P53 ◽  
Author(s):  
Ran Zuo ◽  
Haiqun Yu ◽  
Nan Xu ◽  
Xiaokun He
Keyword(s):  
Gas Phase ◽  
Gas Mixing ◽  
Gas Phase Reactions ◽  
Mocvd Growth
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