Anna Novelli

Bio: Anna Novelli is an academic researcher from Forschungszentrum Jülich. The author has contributed to research in topics: Radical & Isoprene. The author has an hindex of 19, co-authored 42 publications receiving 1482 citations. Previous affiliations of Anna Novelli include Peking University & Max Planck Society.

The reaction of Criegee intermediates with NO, RO2, and SO2, and their fate in the atmosphere

Abstract: The reaction of Criegee intermediates (CI) with NO and RO2 radicals is studied for the first time by theoretical methodologies; additionally, the reaction of CI with SO2 molecules is re-examined. The reaction of CI with NO was found to be slow, with a distinct energy barrier. Their reaction with RO2 radicals proceeds by the formation of a pre-reactive complex followed by addition of the RO2 radical on the CI carbon over a submerged barrier, leading to a larger peroxy radical and opening the possibility for oligomer formation in agreement with experiment. The impact of singlet biradicals on the reaction of CI with SO2 is examined, finding a different reaction mechanism compared to earlier work. For larger CI, the reaction with SO2 at atmospheric pressures mainly yields thermalized sulfur-bearing secondary ozonides. The fate of the CI in the atmosphere is examined in detail, based on observed concentration of a multitude of coreactants in the atmosphere, and estimated rate coefficients available from literature data. The impact of SCI on tropospheric chemistry is discussed.

Wintertime photochemistry in Beijing: observations of RO x radical concentrations in the North China Plain during the BEST-ONE campaign

Abstract: . The first wintertime in situ measurements of hydroxyl (OH), hydroperoxy ( HO2 ) and organic peroxy ( RO2 ) radicals ( ROx = OH + HO 2 + RO 2 ) in combination with observations of total reactivity of OH radicals, kOH in Beijing are presented. The field campaign “Beijing winter finE particle STudy – Oxidation, Nucleation and light Extinctions” (BEST-ONE) was conducted at the suburban site Huairou near Beijing from January to March 2016. It aimed to understand oxidative capacity during wintertime and to elucidate the secondary pollutants' formation mechanism in the North China Plain (NCP). OH radical concentrations at noontime ranged from 2.4 × 10 6 cm - 3 in severely polluted air ( k OH ∼ 27 s - 1 ) to 3.6 × 10 6 cm - 3 in relatively clean air ( k OH ∼ 5 s - 1 ) . These values are nearly 2-fold larger than OH concentrations observed in previous winter campaigns in Birmingham, Tokyo, and New York City. During this campaign, the total primary production rate of ROx radicals was dominated by the photolysis of nitrous acid accounting for 46 % of the identified primary production pathways for ROx radicals. Other important radical sources were alkene ozonolysis (28 %) and photolysis of oxygenated organic compounds (24 %). A box model was used to simulate the OH, HO2 and RO2 concentrations based on the observations of their long-lived precursors. The model was capable of reproducing the observed diurnal variation of the OH and peroxy radicals during clean days with a factor of 1.5. However, it largely underestimated HO2 and RO2 concentrations by factors up to 5 during pollution episodes. The HO2 and RO2 observed-to-modeled ratios increased with increasing NO concentrations, indicating a deficit in our understanding of the gas-phase chemistry in the high NOx regime. The OH concentrations observed in the presence of large OH reactivities indicate that atmospheric trace gas oxidation by photochemical processes can be highly effective even during wintertime, thereby facilitating the vigorous formation of secondary pollutants.

Unimolecular decay strongly limits the atmospheric impact of Criegee intermediates

Abstract: Stabilized Criegee intermediates (SCI) are reactive oxygenated species formed in the ozonolysis of hydrocarbons. Their chemistry could influence the oxidative capacity of the atmosphere by affecting the HOx and NOx cycles, or by the formation of low-volatility oxygenates enhancing atmospheric aerosols known to have an important impact on climate. The concentration of SCI in the atmosphere has hitherto not been determined reliably, and very little is known about their speciation. Here we show that the concentration of biogenic SCI is strongly limited by their unimolecular decay, based on extensive theory-based structure–activity relationships (SARs) for the reaction rates for decomposition. Reaction with water vapor, H2O and (H2O)2 molecules, is the second most important loss process; SARs are also proposed for these reactions. For SCI derived from the most common biogenic VOCs, we find that unimolecular decay is responsible for just over half of the loss, with reaction with water vapor the main remaining loss process. Reactions with SO2, NO2, or acids have negligible impact on the atmospheric SCI concentration. The ambient SCI concentrations are further characterized by analysis of field data with speciated hydrocarbon information, and by implementation of the chemistry in a global chemistry model. The results show a highly complex SCI speciation, with an atmospheric peak SCI concentrations below 1 × 105 molecule cm−3, and annual average SCI concentrations less than 7 × 103 molecule cm−3. We find that SCI have only a negligible impact on the global gas phase H2SO4 formation or removal of oxygenates, though some contribution around the equatorial belt, and in select regions, cannot be excluded.

The reactions of Criegee intermediates with alkenes, ozone, and carbonyl oxides.

Abstract: The reaction of Criegee intermediates with a number of coreactants is examined using theoretical methodologies, combining ROCCSD(T)//M06-2X quantum calculations with theoretical kinetic predictions of the rate coefficients. The reaction of CI with alkenes is found to depend strongly on the substitutions in the reactants, resulting in significant differences in the predicted rate coefficient as a function of the selected alkene and CI. Despite submerged barriers, these entropically disfavored reactions are not expected to affect CI chemistry. The reaction of H2COO + H2COO is found to be barrierless, with a rate coefficient nearing the collision limit, ≥4 × 10−11 cm3 molecule−1 s−1. The dominant reaction products are expected to be carbonyl compounds and an oxygen molecule, though chemically activated reactions may give rise to a plethora of different (per)acids and carbonyl compounds. CI + CI reactions are expected to be important only in laboratory environments with high CI concentrations. The reaction of H2COO with O3 was predicted to proceed through a pre-reactive complex and a submerged barrier, with a rate coefficient of 1 × 10−12 cm3 molecule−1 s−1. A study of the dominant CI reactions under experimental and atmospheric conditions shows that the latter reaction might affect CI chemistry.

Direct observation of OH formation from stabilised Criegee intermediates.

Abstract: The syn-CH3CHOO Criegee intermediate formed from the ozonolysis of propene and (E)-2-butene was detected via unimolecular decomposition and subsequent detection of OH radicals by a LIF-FAGE instrument. An observed time dependent OH concentration profile was analysed using a detailed model focusing on the speciated chemistry of Criegee intermediates based on the recent literature. The absolute OH concentration was found to depend on the steady state concentration of syn-CH3CHOO at the injection point while the time dependence of the OH concentration profile was influenced by the sum of the rates of unimolecular decomposition of syn-CH3CHOO and wall loss. By varying the most relevant parameters influencing the SCI chemistry in the model and based on the temporal OH concentration profile, the unimolecular decomposition rate k (293 K) of syn-CH3CHOO was shown to lie within the range 3–30 s−1, where a value of 20 ± 10 s−1 yields the best agreement with the CI chemistry literature.

Ab initio calculation of vibrational absorption and circular dichroism spectra using density functional force fields

Abstract: : The unpolarized absorption and circular dichroism spectra of the fundamental vibrational transitions of the chiral molecule, 4-methyl-2-oxetanone, are calculated ab initio. Harmonic force fields are obtained using Density Functional Theory (DFT), MP2, and SCF methodologies and a 5S4P2D/3S2P (TZ2P) basis set. DFT calculations use the Local Spin Density Approximation (LSDA), BLYP, and Becke3LYP (B3LYP) density functionals. Mid-IR spectra predicted using LSDA, BLYP, and B3LYP force fields are of significantly different quality, the B3LYP force field yielding spectra in clearly superior, and overall excellent, agreement with experiment. The MP2 force field yields spectra in slightly worse agreement with experiment than the B3LYP force field. The SCF force field yields spectra in poor agreement with experiment.The basis set dependence of B3LYP force fields is also explored: the 6-31G* and TZ2P basis sets give very similar results while the 3-21G basis set yields spectra in substantially worse agreements with experiment. jg

This is How the Discussion Started

Abstract: A copy of Guangbo jiemu bao [Broadcast Program Report] was being passed from hand to hand among a group of young people eager to be the first to read the article introducing the program "What Is Revolutionary Love?" It said: "… Young friends, you are certainly very concerned about this problem'. So, we would like you to meet the young women workers Meng Xiaoyu and Meng Yamei and the older cadre Miss Feng. They are the three leading characters in the short story ‘The Place of Love.’ Through the description of the love lives of these three, the story induces us to think deeply about two questions that merit further examination.

Multiphase chemistry at the atmosphere-biosphere interface influencing climate and public health in the anthropocene.

Abstract: This is an open access article published under a Creative Commons Attribution (CC-BY) License, which permits unrestricted use, distribution and reproduction in any medium, provided the author and source are cited. Review pubs.acs.org/CR Multiphase Chemistry at the Atmosphere−Biosphere Interface Influencing Climate and Public Health in the Anthropocene Ulrich Po schl* and Manabu Shiraiwa* Multiphase Chemistry Department, Max Planck Institute for Chemistry, 55128 Mainz, Germany air contaminants (SHCC) and their multiphase chemical interactions at the atmosphere−biosphere interface, including human lungs and skin, plant leaves, cryptogamic covers, soil, and aquatic surfaces. After an overview of different groups of SHCC, we address the chemical interactions of reactive oxygen species and reactive nitrogen species (ROS, RNS), primary biological and secondary organic aerosols (PBA, SOA), as well as carbonaceous combustion aerosols (CCA) including soot, black/elemental carbon, polycyclic aromatic hydrocarbons, and related compounds (PAH, PAC). ROS and RNS interact strongly with other SHCC and are central to both atmospheric and physiological processes and their coupling through the atmosphere−biosphere interface, for example, in the formation and aging of biogenic and combustion aerosols as well as in CONTENTS inflammatory and allergic immune responses triggered by air pollution. Deposition of atmospheric ROS/RNS and aerosols 1. Introduction and Motivation can damage biological tissues, modify surface microbiomes, and 2. Health- and Climate-Relevant Air Contaminants induce oxidative stress through Fenton-like reactions and 2.1. Reactive Oxygen and Nitrogen Species immune responses. The chemical mechanisms and kinetics are 2.2. Primary Biological Aerosols not yet fully elucidated, but the available evidence suggests that 2.3. Secondary Organic Aerosols multiphase processes are crucial for the assessment, prediction, 2.4. Carbonaceous Combustion Aerosols and handling of air quality, climate, and public health. Caution 2.5. Other Air Contaminants Linking Atmospher- should be taken to avoid that human activities shaping the ic and Physiological Chemistry Anthropocene create a hazardous or pathogenic atmosphere 3. Multiphase Chemical Reactions at Specific Bio- overloaded with allergenic, corrosive, toxic, or infectious logical Interfaces contaminants. 3.1. Lung Lining Fluid Multiphase chemistry deals with chemical reactions, trans- 3.2. Human Skin port processes, and transformations between gaseous, liquid, 3.3. Plant Surfaces and Cryptogamic Covers and solid matter. These processes are essential for Earth system 3.4. Soil and Aquatic Surfaces science and climate research as well as for life and health 4. Conclusions and Outlook sciences on molecular and global levels, bridging a wide range Author Information of spatial and temporal scales from below nanometers to Corresponding Authors thousands of kilometers and from less than nanoseconds to Notes years and millennia as illustrated in Figure 1. Biographies From a chemical perspective, life and the metabolism of most Acknowledgments living organisms can be regarded as multiphase processes References involving gases like oxygen and carbon dioxide; liquids like water, blood, lymph, and plant sap; and solid or semisolid substances like bone, tissue, skin, wood, and cellular 1. INTRODUCTION AND MOTIVATION membranes. Even primitive forms of life and metabolic activity Multiphase chemistry plays a vital role in the Earth system, under anaerobic conditions generally involve multiple liquid climate, and health. Chemical reactions, mass transport, and and solid or semisolid phases structured by cells, organelles, and phase transitions between gases, liquids, and solids are essential membranes. 2 On global scales, the biogeochemical cycling of for the interaction and coevolution of life and climate. chemical compounds and elements, which can be regarded as Knowledge of the mechanisms and kinetics of these processes the metabolism of planet Earth, also involves chemical is also required to address societally relevant questions of global reactions, mass transport, and phase transitions within and environmental change and public health in the Anthropocene, that is, in the present era of globally pervasive and steeply Special Issue: 2015 Chemistry in Climate increasing human influence on planet Earth. 1 In this work, we review the current scientific understanding and recent advances Received: September 1, 2014 in the investigation of short-lived health- and climate-relevant Published: April 9, 2015 © 2015 American Chemical Society DOI: 10.1021/cr500487s Chem. Rev. 2015, 115, 4440−4475

Highly Oxygenated Organic Molecules (HOM) from Gas-Phase Autoxidation Involving Peroxy Radicals: A Key Contributor to Atmospheric Aerosol

Abstract: Highly oxygenated organic molecules (HOM) are formed in the atmosphere via autoxidation involving peroxy radicals arising from volatile organic compounds (VOC). HOM condense on pre-existing particles and can be involved in new particle formation. HOM thus contribute to the formation of secondary organic aerosol (SOA), a significant and ubiquitous component of atmospheric aerosol known to affect the Earth's radiation balance. HOM were discovered only very recently, but the interest in these compounds has grown rapidly. In this Review, we define HOM and describe the currently available techniques for their identification/quantification, followed by a summary of the current knowledge on their formation mechanisms and physicochemical properties. A main aim is to provide a common frame for the currently quite fragmented literature on HOM studies. Finally, we highlight the existing gaps in our understanding and suggest directions for future HOM research.

Tropospheric OH and HO2 radicals: field measurements and model comparisons.

Abstract: The hydroxyl radical, OH, initiates the removal of the majority of trace gases in the atmosphere, and together with the closely coupled species, the hydroperoxy radical, HO2, is intimately involved in the oxidation chemistry of the atmosphere. This critical review discusses field measurements of local concentrations of OH and HO2 radicals in the troposphere, and in particular the comparisons that have been made with numerical model calculations containing a detailed chemical mechanism. The level of agreement between field measurements of OH and HO2 concentrations and model calculations for a given location provides an indication of the degree of understanding of the underlying oxidation chemistry. We review the measurement-model comparisons for a range of different environments sampled from the ground and from aircraft, including the marine boundary layer, continental low-NOx regions influenced by biogenic emissions, the polluted urban boundary layer, and polar regions. Although good agreement is found for some environments, there are significant discrepancies which remain unexplained, a notable example being unpolluted, forested regions. OH and HO2 radicals are difficult species to measure in the troposphere, and we also review changes in detection methodology, quality assurance procedures such as instrument intercomparisons, and potential interferences.