Coralie Schoemaecker

Université de Lille · Department of Chemistry

The cross-reaction of ethyl peroxy radicals (C2H5O2) with methyl peroxy radicals (CH3O2) (R1) has been studied using laser photolysis coupled to time resolved detection of the two different peroxy radicals by continuous wave cavity ring down spectroscopy (cw-CRDS) in their AÃ-X̃ electronic transition in the near-infrared region, C2H5O2 at 7602.25 c...

INDAIRPOLLNET (INDoor AIR POLLution NETwork https://indairpollnet.eu/) is a European COST Action network programme, running from September 2018 until March 2023. It has more than 200 indoor and outdoor air quality scientists from universities, large and small companies, and research institutes around Europe and beyond. Their expertise covers chemis...

A human-occupied indoor space shares many similarities with Earth and its atmosphere.

Radicals and their precursors play a central role in the chemical transformations occurring in indoor air and on indoor surfaces. Such species include OH, HO2, peroxy radicals, nitrous acid, reactive chlorine species, NO3, N2O5, Criegee intermediates, and glyoxal and methylglyoxal. Recent advances on instrumental analysis and modeling studies have...

The importance of photolysis as an initiator of air chemistry outdoors is widely recognized, but its role in chemical processing indoors is often ignored. This paper uses recent experimental data to modify a detailed chemical model, using it to investigate the impacts of glass type, artificial indoor lighting, cloudiness, time of year and latitude...

The absolute absorption cross-section of the ethyl peroxy radical C2H5O2 in the Ã←X˜ electronic transition with the peak wavelength at 7596 cm−1 has been determined by the method of dual wavelengths time resolved continuous wave cavity ring down spectroscopy. C2H5O2 radicals were generated from pulsed 351 nm photolysis of C2H6/Cl2 mixture in presen...

The absolute absorption cross section of the ethyl peroxy radical, C2H5O2, in the Ã←X ̃ electronic transition with the peak wavelength at 7596 cm-1, has been determined by the method of dual wavelengths time resolved continuous wave cavity ring down spectroscopy. C2H5O2 radicals were generated from pulsed 351 nm photolysis of C2H6/Cl2 mixture in pr...

Trace gas measurements were performed during the LANDEX (the LANDes EXperiment) Episode 1 field campaign in the summer 2017, in one of the largest European maritime pine forests (> 95% Pinus pinaster) located in southwestern France. Efforts have been focused on obtaining a good speciation of 20 major biogenic volatile organic compounds (BVOCs, incl...

“In developed countries, we spend 80%-90% of our time indoors” is the opening sentence for most grant applications and publications in our field. But has this well-worn truism lost its impact? We know that the majority of our exposure to air pollution occurs indoors, so why has indoor air quality not received the attention it deserves and how do we...

Recent publications suggested that water catalyzes the reaction of OH radicals with alcohols (R. A. Jara-Toro; F. J. Hernandez; R. A. Taccone; S. I. Lane; G. A. Pino. Angew. Chem. Int. Ed. 2017, 56, 2166 for methanol and R. A. Jara-Toro; F. J. Hernandez; M. d. l. A. Garavagno; R. A. Taccone; G. A. Pino. Phys. Chem. Chem. Phys. 2018, 20, 27885 for e...

Total hydroxyl radical (OH) reactivity measurements were conducted during the LANDEX intensive field campaign in a coniferous temperate forest located in the Landes area, southwestern France, during July 2017. In order to investigate inter-canopy and intra-canopy variability, measurements were performed inside (6 m) and above the canopy level (12 m...

Total OH reactivity measurements were conducted during the LANDEX intensive field campaign in a coniferous temperate forest located in the Landes area, south-western France, during July 2017. In order to investigate inter-canopy and intra-canopy variability, measurements were performed inside (6 m) and above the canopy level (12 m), as well as at t...

In a context where a significant fraction of the population lives near industrial areas, the main objectives of this study are to provide (a) new data on PM2.5 chemical compositions, heavy-metal concentrations and trace gases released by metalworking activities and (b) new information on the near-field evolution (up to about a thousand meters) of s...

Recent works [Jara‐Toro et al., Angew. Chem. Int. Ed. 2017, 56, 2166 and PCCP 2018, 20, 27885] suggest that the rate coefficient of OH reactions with alcohols would increase by up to 2 times from dry to high humidity. This finding would have an impact on the budget of alcohols in the atmosphere and that it may explain differences in measured and mo...

Recent works [Jara‐Toro et al., Angew. Chem. Int. Ed. 2017, 56, 2166 and PCCP 2018, 20, 27885] suggest that the rate coefficient of OH reactions with alcohols would increase by up to 2 times from dry to high humidity. This finding would have an impact on the budget of alcohols in the atmosphere and that it may explain differences in measured and mo...

Field campaigns have been carried out with the FAGE (fluorescence assay by gas expansion) technique in remote biogenic environments in the last decade to quantify the in situ concentrations of OH, the main oxidant in the atmosphere. These data have revealed concentrations of OH radicals up to a factor of 10 higher than predicted by models, whereby...

Methanol is a benchmark for understanding tropospheric oxidation, but is underpredicted by up to 100% in atmospheric models. Recent work has suggested this discrepancy can be reconciled by the rapid reaction of hydroxyl and methylperoxy radicals with a methanol branching fraction of 30%. However, for fractions below 15%, methanol underprediction is...

The assessment of VOC emission rates and sorption coefficients was performed for ten surfaces present within a classroom, using field and laboratory emission cells (FLEC) coupled to online and offline VOC quantification techniques. 21 identified VOCs were emitted by the different surfaces. VOC emission rates measured using PTR‐ToF‐MS were compared...

Field campaigns have been carried out with the FAGE technique in remote biogenic environments in the last decade to quantify the in situ concentrations of OH, the main oxidant in the atmosphere. These data have revealed concentrations of OH radicals up to a factor of 10 higher than predicted by models, whereby the disagreement increases with decrea...

The HO2 yield in the reaction of peroxy radicals with OH radicals has been determined experimentally at 50 Torr helium by measuring simultaneously OH and HO2 concentration time profiles, following the photolysis of XeF2 in the presence of different hydrocarbons and O2. The following yields have been obtained: = (0.90 ± 0.1), = (0.75 ± 0.15), = (0.4...

The absorption spectrum of HO2 radicals has been measured in the range 6636–6639 cm⁻¹ at several pressures between 20 and 760 Torr of air. Absolute absorption cross sections of the strongest line at around 6638.2 cm⁻¹ have been determined from kinetic measurements, taking advantage of the well known rate constant of the self-reaction. Peak absorpti...

The characteristics of indoor light (intensity, spectral, spatial distribution) originating from outdoors have been studied using experimental and modeling tools. They are influenced by many parameters such as building location, meteorological conditions and the type of window. They have a direct impact on indoor air quality through a change in che...

Xenondifluoride, XeF2, has been photolysed in the presence of methanol, CH3OH to study the reaction of F-atoms with methanol. Two reaction pathways are possible: F + CH3OH → CH2OH + HF (R1) F + CH3OH → CH3O + HF (R2) Both products, CH2OH and CH3O are converted to HO2 in the presence of O2. The rate constants for the reaction of both radicals with O...

The chemical composition of indoor air changes due to the reactive nature of the indoor environment. Historically, only the stable parent compounds were investigated due to their ease of measurement by conventional methods Today, however, scientists can better characterize oxidation products (gas and particulate-phase) formed by indoor chemistry. A...

Hydroxyl (OH) radical reactivity (kOH) has been measured for 18 years with different measurement techniques. In order to compare the performances of instruments deployed in the field, two campaigns were conducted performing experiments in the atmospheric simulation chamber SAPHIR at Forschungszentrum Jülich in October 2015 and April 2016. Chemical...

Hydroxyl (OH) radical reactivity (kOH) has been measured for 18 years with different measurement techniques. In order to compare the performances of instruments deployed in the field, two campaigns were conducted performing experiments in the atmospheric simulation chamber SAPHIR at Forschungszentrum Jülich in October 2015 and April 2016. Chemical...

Hydroxyl (OH) radical reactivity (kOH) has been measured for 18 years with different measurement techniques. In order to compare the performances of instruments deployed in the field, two campaigns were conducted performing experiments in the atmospheric simulation chamber SAPHIR at Forschungszentrum Jülich in October 2015 and April 2016. Chemical...

The rate constants for the reaction of three peroxy radicals with OH have been measured using different precursors. Peroxy radicals have been prepared by either the reaction of Cl-atoms with C2H6, C3H8 and n-C4H10 or through photolysis of the corresponding alkyliodide. Using Cl-atoms, the following rate constants have been measured:C2H5O2+OH→produc...

The absorption spectrum of the à ²A’ ← ²A” 000-000 band of HO2 and DO2 radicals has been measured in the range 6941 – 7077 cm⁻¹ with a resolution of around 0.005 cm⁻¹. HO2 and DO2 radicals were generated from the reaction of Cl-atoms with CH3OH and CD3OD, respectively, whereby Cl-atoms were generated by pulsed photolysis of (COCl)2 at 248nm. One ti...

The reaction between CH3O2 and OH radicals has been shown to be fast and to play an appreciable role for the removal of CH3O2 radials in remote environments such as the marine boundary layer. Two different experimental techniques have been used here to determine the products of this reaction. The HO2 yield has been obtained from simultaneous time-r...

The reaction between CH3O2 and OH radicals has been studied in a laser photolysis cell using the reaction of F-atoms with CH4 and H2O for the simultaneous generation of both radicals, with F-atoms generated through 248 nm photolysis of XeF2. An experimental set-up combining cw-Cavity Ring Down Spectroscopy (cw-CRDS) and high repetition rate laser i...

The pollutant pattern inside a low energy school building, equipped with a time controlled ventilation system, has been investigated by two approaches. In a first step, 4.5-days passive sampling measurements have been done simultaneously inside and outside, in order to determine the chemical fingerprint and the origin of the pollutants. In a second...

In order to study the dynamic of pollutants and the chemistry in a low energy-consumption building as a function of the ventilation status and outdoor conditions, fields campaigns have been conducted in a low energy school in northern France. A large set of instruments has been deployed to characterize with a high temporal resolution (range of minu...

The photolysis of HONO has been found to be the oxidation driver through OH formation in the indoor air measurement campaign SURFin, an extensive campaign carried out in July 2012 in a classroom in Marseille. In the present study, the INCA-Indoor model is used to evaluate different HONO formation mechanisms that have been used previously in indoor...

OH and HO2 profiles measured in a real environment have been compared to the results of the INCA-Indoor model to improve our understanding of indoor chemistry. Significant levels of both radicals have been measured and their profiles display similar diurnal behavior, reaching peak concentrations during direct sunlight (up to 1.6 × 10(6) and 4.0 × 1...

A test emission chamber called CLIMPAQ has been coupled to a chromatography analyzer GC to measure volatile organic compounds (VOC) concentration during a sorption experiments (Fast sorption measurements of VOCs on building materials: Part 2 – Comparison between FLEC and CLIMPAQ methods, (Rizk et al., In press) [1]). The equations used to calculate...

To study the reactivity in different environments : urban or biogenic To test the reliability of the different instruments available (pump-probe, CRM) to measure OH reactivity in these environments  To study the reactivity of specific biogenic species in laboratory (i.e : isoprene, monoterpenes, playing a role in the production of tropospheric oz...

A Proton Transfer Reaction-Mass Spectrometer (PTR-MS) has been coupled to the outlet of a Field and Laboratory Emission Cell (FLEC), to measure volatile organic compounds (VOC) concentration during a sorption experiments (Rizk et al., in press) [1]. The limits of detection of the PTR-MS for three VOCs are presented for different time resolution (2,...

Several physicochemical processes occurring within buildings are key drivers of indoor concentrations of Volatile Organic Compounds VOCs. Many models and experimental studies have been proposed to predict VOCs concentration indoors given these processes. However, there is a lack of representative data in literature to present gas–surface interactio...

Indoor air quality was characterized in ten recently built energy-efficient French schools during two periods of 4.5 days. Carbon dioxide time-resolved measurements during occupancy clearly highlight the key role of the ventilation rate (scheduled or occupancy indexed), especially in this type of building, which was tightly sealed and equipped with...

The investigation of hydroxyl radical (OH) chemistry during intensive field campaigns has led to the development of several techniques dedicated to ambient measurements of total OH reactivity, which is the inverse of the OH lifetime. Three techniques are currently used during field campaigns, including the total OH loss rate method, the pump–probe...

The investigation of hydroxyl radical (OH) chemistry during intensive field campaigns has led to the development of several techniques dedicated to ambient measurements of total OH reactivity, which is the inverse of the OH lifetime. Three techniques are currently used during field campaigns, including the total OH loss rate method, the pump-probe...

A new method has been developed to measure sorption parameters on indoor surfaces on the field, based on the coupling of a Field and Laboratory Emission Cell (FLEC) and a Proton Transfer Reaction - Mass Spectrometer (PTR-MS). In this work, the method used for field applications is compared to the conventional method (used for laboratory scale exper...

Pollutant concentrations in the indoor environment are controlled by numerous physical and chemical processes. In energy-efficient buildings, modern materials are used and ventilation is controlled. These specific conditions based on energy saving considerations can have a strong impact on Indoor Air Quality (IAQ). The MERMAID project aims at chara...

A transportable device based on the coupling of a Field and Laboratory Emission Cell (FLEC) and a Proton Transfer Reaction - Mass Spectrometer (PTR-MS) has been used for the first time to perform in-situ measurements of sorption parameters. The measurements were carried out during an intensive field campaign conducted in a low energy French school....

The aim of the NANO-INDUS project was to study the evolution of the physico-chemical properties of industrial fine particles over a short-range distance, after their release from the stacks. First, measurements were performed directly at the stacks of a plant manufacturing iron-manganese alloy near Dunkirk Port, France. Separately, an intensive fie...

The rate constant of the reactionC2H5O2 + OH → Products has been measured at T = 296 K using laser photolysis coupled to CRDS and LIF. C2H5O2 was generated from the reaction of Cl-atoms with C2H6 at 55 Torr O2, whereby Cl-atoms were generated by 248 nm photolysis of (COCl)2. OH radicals were generated simultaneously by photolysing H2O2. The initial...

Adsorption and desorption of Volatile Organic compounds (VOCs) on indoor surfaces are key drivers of indoor concentrations. Sorption coefficients were investigated in emission test chambers and then introduced in Indoor Air Quality model to predict concentrations in real environments. Since predicted concentrations are different from measured ones...

In France, due to the recent thermal regulation and the low emissivity standards for materials, changes are ongoing in building conceptions. The goal of the MERMAID program is to investigate Indoor Air Quality in low energy buildings through a joint experimental and modeling approach. The experimental part includes: -a preliminary campaign, to meas...

The aim of the MERMAID project is to assess the air quality in low energy buildings. In the framework of this project, a new Indoor Air Quality (IAQ) model, called INCA-Indoor is developed. The objective is to propose a numerical tool able to analyze the contribution of the physical and chemical processes occurring in the specific indoor conditions...

All public buildings in France have to comply with the 2011 French IAQ regulations, setting limit values of 30 μg/m3 and 5 μg/m3 for formaldehyde and benzene respectively. In this work, we conducted a campaign in 10 low energy schools to check for the compliance with the regulations, and to search for possible specific pollution patterns in LEPB. P...

Radical quantum yields have been measured following the 248 nm photolysis of acetaldehyde, CH3CHO. HCO radical and H atom yields have been quantified by time resolved continuous wave Cavity Ring Down Spectroscopy in the near infrared following their conversion to HO2 radicals by reaction with O2. The CH3 radical yield has been determined using the...

In the present work, measurements of absolute mole fraction profiles of CN and HCN were jointly performed in low pressure (5.3 kPa) premixed CH4/O2/N2 flames of three equivalent ratios (ϕ = 0.8–1.25). These species were the missing link of the database comprising CH, NCN, NCO and NO species previously acquired in Lille to improve detailed mechanism...

ABSTRACT: Rate and equilibrium constants for the reaction of HO2 with formaldehyde CH2O+HO2 ↔ HOCH2O2 (R1) and acetaldehyde CH3CHO+HO2 ↔ CH3CH(OH)O2 (R2) havebeendirectlymeasured.TheconcentrationofHO2 radicalswasfollowedinatime-resolved method by coupling cw-CRDS (cavity ringdown spectroscopy) to laser photolysis. The reaction of HO2 with CH2O (R1)...

An instrument implementing Incoherent BroadBand Cavity-Enhanced Absorption Spectroscopy (IBBCEAS) for quantitative measurements of molecular iodine (I2) at ambient pressure and in the presence of aerosols is presented. The instrument is based on a LED emitting in the green spectral region around 500–550 nm, exciting a multitude of rovibronic transi...

Significance The design of internal combustion engines relies on a good understanding of the kinetic mechanism of the autoignition of hydrocarbons. •OH and •HO 2 radicals are known to be the key species governing all stages of the development of ignition. A direct measurement of these radicals under low-temperature oxidation conditions has been ach...

The absorption spectrum of CH3O2 radicals and CH3I molecules has been measured in the range 7473 - 7497 cm-1. CH3O2 radicals have been generated by 248 nm laser photolysis of CH3I in the presence of O2 and the relative absorption has been measured by time resolved cw-CRDS. Calibration of the relative absorption spectrum has been carried out on thre...

The gas-phase oxidation of n-butane has been studied in an atmospheric jet-stirred reactor (JSR) at temperatures up to 950 K. For the first time, continuous wave cavity ring-down spectroscopy (cw-CRDS) in the near-infrared has been used, together with gas chromatography (GC), to analyze the products formed during its oxidation. In addition to the q...

The hydroxyl (OH) radical is the most important oxidant in the atmosphere since it controls its self-oxidizing capacity. The main sources of OH radicals are the photolysis of ozone and the photolysis of nitrous acid (HONO). Due to the attenuation of solar radiation in the indoor environment, the possibility of OH formation through photolytic pathwa...

A novel instrument for measuring total HO2 reactivity in the troposphere was successfully developed using a laser-flash photolysis and laser-induced fluorescence detection technique. Validation and testing were conducted through kinetic measurements of the reaction of HO2 radicals with NO2, and the results were found to be in good agreement with re...

The hydroxyl radical (OH) drives the oxidation of organic trace gases that can lead to the production of ozone and secondary organic aerosols in the atmosphere. A complete understanding of the sources and sinks of OH is therefore important to address issues related to both air quality and climate change. However, recent measurements of total OH rea...

Work on the relevance of the reaction of excited NO2 with water vapour as an atmospheric source of OH radicals is presented and measurement of absolute absorption cross sections of HONO in the near infrared are reported.

In April 2010, we performed a 9 days intercomparative measurement at the SAPHIR chamber (Juelich, Germany) between the FZJ-LIF (Forschungszentrum Jülich – Laser Induced Fluorescence) and the newly developed UL-FAGE (University of Lille – Fluorescence Assay by Gas Expansion) in the frame of the European project Eurochamp 2 which aims at integrating...

Absolute absorption cross sections of formaldehyde, CH2O, have been measured at total pressures of 14.5 and 66 mbar Helium by cw-CRDS for two selected lines at around 6625 cm−1. Absolute CH2O concentrations have been determined in situ by measuring the pseudo-first order decays of OH radicals using high repetition rate laser induced fluorescence (L...

A new FAGE setup has recently been built at the University of Lille, France. It permits the quantification of OH and HO2 in the atmosphere with a detection limit of 3 x 105 molecules/(cm3 x min) for OH and 1 x 10(6) molecules/(cm3 x min) for HO2. Its coupling to a photolysis cell enables the measurement of the total reactivity of the hydroxyl radic...

The first reliable quantification of hydrogen peroxide (H(2)O(2)) formed during the low-temperature oxidation of an organic compound has been achieved thanks to a new system that couples a jet stirred reactor to a detection by continuous wave cavity ring-down spectroscopy (cw-CRDS) in the near-infrared. The quantification of this key compound for h...

Hydrogen peroxide (H2O2) is an important reactive oxygen species (ROS) involved in photocatalysis. To study the photocatalytic behavior of H2O2, the decomposition of H2O2 on illuminated TiO2 films was investigated using cavity ring down spectroscopy (CRDS). A mixture of H2O2 and O2 gas was flowed through a cavity reactor which contained a TiO2-coat...

We present the coupling of a jet-stirred reactor to detection by cw-CRDS in the near infrared and first results obtained during the oxidation of methane. The mixture is rapidly expanded from the jet-stirred reactor into a 80 cm-long cw-CRDS cell maintained at a the pressure around 1.33 kPa, thus freezing the reaction and decreasing pressure broaden...

The excitation energy dependence of HO(2) radical formation from the 248 nm irradiation of four different aromatic hydrocarbons (benzene, toluene, o-xylene, and mesitylene) in the presence of O(2) has been studied. HO(2) has been monitored at 6638.20 cm(-1) by cw-CRDS, and the formation of a short-lived, unidentified species, showing broad-band abs...