A5070722681- Atmospheric chemistry and aerosols
- Atmospheric Ozone and Climate
- Atmospheric and Environmental Gas Dynamics
- Air Quality and Health Impacts
- Air Quality Monitoring and Forecasting
- Mercury impact and mitigation studies
- Toxic Organic Pollutants Impact
- Water Quality Monitoring and Analysis
- Spectroscopy and Laser Applications
- Various Chemistry Research Topics
- Erosion and Abrasive Machining
- Atmospheric aerosols and clouds
- Odor and Emission Control Technologies
- Laser-induced spectroscopy and plasma
- Injection Molding Process and Properties
- Plant responses to elevated CO2
- Analytical chemistry methods development
- Particle Dynamics in Fluid Flows
- Catalytic Processes in Materials Science
- Marine and coastal ecosystems
- Catalysis and Oxidation Reactions
- Vehicle emissions and performance
- Advanced Chemical Sensor Technologies
- Electrochemical sensors and biosensors
- Analytical Chemistry and Sensors
Max Planck Institute for Chemistry
2012-2021
University Medical Center of the Johannes Gutenberg University Mainz
2016-2021
Johannes Gutenberg University Mainz
2016-2021
University of Miami
2012-2017
Forschungszentrum Jülich
2016
California Institute of Technology
2016
Auburn University at Montgomery
2005
Abstract. Measurements of OH and HO2 radicals were conducted in a pine-dominated forest southern Finland during the HUMPPA-COPEC-2010 (Hyytiälä United Photochemistry Particles Air – Comprehensive Organic Precursor Emission Concentration study) field campaign summer 2010. Simultaneous side-by-side measurements hydroxyl with two instruments using chemical ionization mass spectrometry (CIMS) laser-induced fluorescence (LIF), indicating small systematic disagreement, OHLIF / OHCIMS = (1.31 ±...
Abstract. Atmospheric measurements of hydroxyl radicals (OH) are challenging due to a high reactivity and consequently low concentration. The importance OH as an atmospheric oxidant has motivated sustained effort leading the development number highly sensitive analytical techniques. Recent work indicated that laser-induced fluorescence molecules method based on assay by gas expansion technique (LIF-FAGE) for measurement in some environments may be influenced artificial generated within...
Abstract. We analysed the extensive dataset from HUMPPA-COPEC 2010 and HOPE 2012 field campaigns in boreal forest rural environments of Finland Germany, respectively, estimated abundance stabilised Criegee intermediates (SCIs) lower troposphere. Based on laboratory tests, we propose that background OH signal observed our IPI-LIF-FAGE instrument during aforementioned is caused at least partially by SCIs. This hypothesis based correlations with temperature concentrations unsaturated volatile...
Abstract. 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 field, two campaigns were conducted performing experiments atmospheric simulation chamber SAPHIR at Forschungszentrum Jülich October 2015 and April 2016. Chemical conditions chosen either be representative atmosphere or test potential limitations instruments. All types that are currently used measurements one...
Abstract. Laser-induced fluorescence (LIF) is a widely used technique for both laboratory-based and ambient atmospheric chemistry measurements. However, LIF instruments require calibrations in order to translate instrument response into concentrations of chemical species. Calibration measuring OH HO2 (HOx) typically involves the photolysis water vapor by 184.9 nm light, thereby producing quantitative amounts HO2. For ground-based HOx instruments, this method calibration done at one pressure...
Abstract. In situ airborne measurements of OH and HO2 with the HORUS (HydrOxyl Radical measurement Unit based on fluorescence Spectroscopy) instrument were performed in summertime upper troposphere across Europe during HOOVER 2 (HOx OVer EuRope) campaign July 2007. Complementary trace gas species photolysis frequencies conducted to obtain a broad data set, which has been used quantify significant HOx sources sinks. this study we compare simulated mixing ratios from constrained box model...
Abstract. Various atmospheric sources and sinks regulate the abundance of tropospheric formaldehyde (HCHO), which is an important trace gas impacting HOx (≡ HO2 + OH) budget concentration ozone (O3). In this study, we present formation destruction terms ambient HCHO O3 calculated from in situ observations various gases measured at three different sites across Europe during summertime. These include a coastal site Cyprus, scope Cyprus Photochemistry Experiment (CYPHEX) 2014, mountain southern...
Abstract. Hydrogen peroxide (H2O2) plays a significant role in the oxidizing capacity of atmosphere. It is an efficient oxidant liquid phase and serves as temporary reservoir for hydroxyl radical (OH), most important agent gas phase. Due to its high solubility, removal H2O2 due wet dry deposition efficient, being sink HOx (OH+HO2) radicals. In continental boundary layer, budget controlled by photochemistry, transport processes. Here we use situ observations account chemical source mechanisms...
Absolute room temperature (294 ± 2 K) absorption cross sections for the Ã(1)A(2)-X̃(1)A(1) electronic transition of formaldehyde have been measured over spectral range 30,285-32,890 cm(-1) (304-330 nm) using ultraviolet (UV) laser spectroscopy. Accurate high-resolution are essential atmospheric monitoring and understanding photochemistry this important compound. Absorption were obtained at an instrumental resolution better than 0.09 cm(-1), which is slightly broader Doppler width a...
Abstract. The operation of a laser-based sensor for gas-phase elemental mercury, Hg(0), is described. It utilizes sequential two-photon laser excitation with detection blue-shifted laser-induced fluorescence (LIF) to provide highly specific scheme that precludes anything other than atomic mercury. has high sensitivity, fast temporal resolution, and can be deployed in situ measurements the open atmosphere essentially no perturbation environment. An ambient sample also pulled through cell,...
Programmable Thermal Dissociation (PTD) has been used to investigate the chemical speciation of Reactive Gaseous Mercury (RGM, Hg2+). RGM was collected on denuders and analyzed using PTD. The technique tested in a field campaign at coal-fired power plant Pensacola, Florida. Stack gas samples were from ducts located after electrostatic precipitator prior entering stack. An airship sample stack plume, downwind exit. PTD profiles these compared with HgCl2. Comparison in-plume suggest that are...
Abstract. We analysed the extensive dataset from HUMPPA-COPEC 2010 and HOPE 2012 field campaigns in boreal forest rural environments of Finland Germany, respectively, estimated abundance stabilised Criegee intermediates (SCI) lower troposphere. Based on laboratory tests, we propose that background OH signal observed our IPI-LIF-FAGE instrument during afore-mentioned is caused at least partially by SCI. This hypothesis based correlations with temperature concentrations unsaturated volatile...
The relative quantum yield for the production of radical products, H + HCO, from UV photolysis formaldehyde (HCHO) has been measured using a pulsed laser photolysis–pulsed induced fluorescence (PLP–PLIF) technique across 30,400–32,890 cm(–1) (304–329 nm) spectral region Ã(1)A2–X̃(1)A1 electronic transition. had bandwidth 0.09 cm(–1), which is slightly broader than Doppler width rotational line at 300 K (0.07 cm(–1)), and spectrum shows detailed structure. HCO photofragments were monitored...
Abstract. The University of Miami (UM) deployed a sequential two-photon laser-induced fluorescence (2P-LIF) instrument for the in situ measurement gaseous elemental mercury, Hg(0), during Reno Atmospheric Mercury Intercomparison Experiment (RAMIX) campaign. A number extended sampling experiments, typically lasting 6–8 h but on one occasion extending to ∼ 24 h, were conducted, allowing 2P-LIF measurements Hg(0) concentrations be compared with two independently operated instruments using gold...
Abstract. Ambient measurements of hydroxyl radicals (OH) are challenging due to a high reactivity and consequently low concentration. The importance OH as an atmospheric oxidant has resulted in sustained effort leading the development number analytical techniques. Recent work indicated that laser-induced fluorescence molecules method based on assay by gas expansion technique (LIF-FAGE) for measurement some environments may be influenced artificial generated within instrument, chemical remove...
Abstract. Measurements of OH and HO2 radicals were conducted in a~pine dominated forest Southern Finland during the HUMPPA-COPEC-2010 (Hyytiälä United Photochemistry Particles Air – Comprehensive Organic Precursor Emission Concentration study) field campaign summer 2010. Simultaneous side-by-side measurements hydroxyl with two instruments using chemical ionization mass spectrometry (CIMS) laser-induced fluorescence (LIF), indicating good agreement. Subsequently, LIF instrument was moved to...
Abstract. 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 field, two campaigns were conducted performing experiments atmospheric simulation chamber SAPHIR at Forschungszentrum Jülich October 2015 and April 2016. Chemical conditions chosen either be representative atmosphere or test potential limitations instruments. All types that are currently used measurements took...
Abstract. The use of programmable thermal dissociation (PTD) as an approach to investigating the chemical speciation reactive gaseous mercury (RGM, Hg2+) has been explored in a field study. In this RGM is collected on denuder and analyzed using PTD. placed oven measured, function temperature, by monitoring evolution elemental (GEM, Hg0) real time laser-induced fluorescence (LIF). technique was tested campaign at coal-fired power plant Pensacola, Florida. Uncoated tubular denuders were used...
Abstract. In-situ airborne measurements of OH and HO2 with the HORUS (HydrOxyl Radical measurement Unit based on fluorescence Spectroscopy) instrument were performed in summertime upper troposphere across Europe during HOOVER 2 (HOx OVer EuRope) campaign July 2007. Complementary trace gas species photolysis frequencies conducted to obtain a broad data set, which has been used quantify significant HOx sources sinks. In this study we compare in-situ simulated mixing ratios from constrained box...
Abstract. Hydrogen peroxide (H2O2) plays a significant role in the oxidizing capacity of atmosphere. It is an efficient oxidant liquid phase, and serves as temporary reservoir for hydroxyl radical (OH), most important agent gas phase. Due to its high solubility, removal H2O2 due wet dry deposition efficient, being sink HOx (OH + HO2) radicals. In continental boundary layer, budget controlled by photochemistry, transport processes. Here we use in-situ observations H2O2, account chemical...
Dr. Schofield [1] states that:[...]
Table SI-1.Average concentrations with 1σ standard deviation of measured unsaturated VOC 2