A5065075201- Atmospheric chemistry and aerosols
- Atmospheric Ozone and Climate
- Spectroscopy and Laser Applications
- Air Quality Monitoring and Forecasting
- Atmospheric and Environmental Gas Dynamics
- Water Quality Monitoring and Analysis
- Atmospheric aerosols and clouds
- Astro and Planetary Science
- Air Quality and Health Impacts
- Mass Spectrometry Techniques and Applications
- Fluorine in Organic Chemistry
- Astrophysics and Star Formation Studies
- Catalytic Processes in Materials Science
- Advanced Chemical Physics Studies
- Wastewater Treatment and Nitrogen Removal
- Ion-surface interactions and analysis
- Constructed Wetlands for Wastewater Treatment
- Solar Radiation and Photovoltaics
- Solar and Space Plasma Dynamics
- Synthesis and Reactions of Organic Compounds
- Adaptive optics and wavefront sensing
- Isotope Analysis in Ecology
- Smart Materials for Construction
- Origins and Evolution of Life
- Odor and Emission Control Technologies
University of Leeds
2006-2013
University of Birmingham
1987-2005
University of York
2000
High Altitude Observatory
1956
Abstract. The lifetime of methane is controlled to a very large extent by the abundance OH radical. tropics are key region for removal, with oxidation in lower tropical troposphere dominating global removal budget (Bloss et al., 2005). In forested environments where biogenic VOC emissions high and NOx concentrations low, assumed be low due rapid reactions sink species such as isoprene. New, simultaneous measurements reactivity, k'OH, Borneo rainforest reported show much higher than...
Abstract. Fluorescence Assay by Gas Expansion (FAGE) has been used to detect ambient levels of OH and HO2 radicals at the Cape Verde Atmospheric Observatory, located in tropical Atlantic marine boundary layer, during May June 2007. Midday radical concentrations were high, with maximum 9 ×106 molecule cm−3 6×108 observed for HO2, respectively. A box model incorporating detailed Master Chemical Mechanism, extended include halogen chemistry, heterogeneous loss processes constrained all...
Laboratory studies were conducted to investigate the kinetics of HO2 radical uptake onto submicron inorganic salt aerosols. reactive coefficients measured at room temperature using an aerosol flow tube and Fluorescence Assay by Gas Expansion (FAGE) technique that allowed for measurements be under atmospherically relevant concentrations ([HO2] = 108 109 molecule cm−3). The coefficient dry aerosols was consistently below detection limit (γHO2 < 0.004). mass accommodation radicals Cu(II)-doped...
Abstract. The reactions of ozone with alkenes are an important source hydroxyl (OH) radicals; however, quantification their importance is hindered by uncertainties in the absolute OH yield. Hydroxyl radical yields for gas-phase ozonolysis isoprene determined this paper four different methods: (1) use cyclohexane as scavenger, and production cyclohexanone, (2) 1,3,5-trimethylbenzene tracer, diminution its concentration, (3) A kinetic method which yield was obtained performing a series...
Copper(I) trifluoromethanethiolate reacts with a range of diazonium salts containing electron-withdrawing groups to give the corresponding trifluoromethyl aryl sulfides in high yield; it is also possible carry out diazotisation and trifluoromethylthiolation one pot directly from anilines.
The kinetics of the reaction between O atoms and OH radicals, both in their electronic ground state, have been investigated at temperatures down to ca. 39 K. experiments employed a CRESU (Cinétique deRéaction en Ecoulement Supersonique Uniforme) apparatus attain low temperatures. Both reagents were created using pulsed laser photolysis 157.6 nm mixtures containing H2O O2 diluted N2 carrier gas. radicals formed by direct O(1D) H2O. O(3P) as product rapid quenching that O2. rates removal...
Abstract. A field instrument utilising the artificial generation of OH radicals in a sliding injector flow-tube reactor with detection by laser-induced fluorescence spectroscopy has been developed to measure rate decay reaction its atmospheric sinks. The reactivity calibrated using known concentrations CO, NO2 and single hydrocarbons flow zero air, impact recycling via HO2+NO→OH+NO2 on measured quantified. As well as detailed description apparatus, capabilities new are illustrated...
Abstract. The NERC UK SOLAS-funded Reactive Halogens in the Marine Boundary Layer (RHaMBLe) programme comprised three field experiments. This manuscript presents an overview of measurements made within two simultaneous remote experiments conducted tropical North Atlantic May and June 2007. Measurements were from mobile one ground-based platforms. heavily instrumented cruise D319 on RRS Discovery Lisbon, Portugal to São Vicente, Cape Verde back Falmouth, was used characterise spatial...
Abstract. The design of a Highly Instrumented Reactor for Atmospheric Chemistry (HIRAC) is described and initial results obtained from HIRAC are presented. ability to perform in-situ laser-induced fluorescence detection OH HO2 radicals with the Fluorescence Assay by Gas Expansion (FAGE) technique establishes it as internationally unique chamber its size pressure/temperature variable capabilities. In addition FAGE technique, features suite analytical instrumentation, including: multipass FTIR...
The kinetics of reactions the OH radical with ethene, ethyne (acetylene), propyne (methyl acetylene) and t-butyl-hydroperoxide were studied at temperatures 69 86 K using laser flash-photolysis combined laser-induced fluorescence spectroscopy. A new pulsed Laval nozzle apparatus is used to provide low-temperature thermalised environment a single density approximately 4x10(16) molecule cm(-3) in N2. temperature within flow are determined measurements impact pressure rotational populations from...
The rate coefficients (k) for reactions of OH with acetone, methyl ethyl ketone (MEK) and dimethyl ether (DME) have been measured in the temperature range 86-112 K using a pulsed Laval nozzle apparatus. Large increases k at lower temperatures were observed, k(86K)/k(295K) = 334 k(93K)/k(295K) 72 3, MEK DME respectively. A mechanism involving formation hydrogen bonded complex prior to an overall barrier on potential energy surface is proposed explain this behaviour.
The design of and initial results obtained from a multipass matrix system (MMS) for mid-infrared spectroscopy that operates in the Highly Instrumented Reactor Atmospheric Chemistry (HIRAC) recently constructed School at University Leeds, is described. HIRAC an evacuable, temperature variable, photochemical atmospheric reaction chamber. MMS modified Chernin cell, utilizing three objective mirrors two field mirrors. In addition to providing paraxial equations required throughput matched cell...
A time-resolved time-of-flight mass spectrometer (TOF-MS) that can simultaneously monitor multiple species on the millisecond time scale has been constructed. pulsed photolysis laser is used to initiate reaction, and then via a pinhole reaction mixture sampled by TOF-MS. The ions are created photoionization either discharge lamp or laser. Comparison between two ionization sources showed at least an order of magnitude more efficient, based accumulate data. Also, unlike continuous not limited....
Abstract In this paper, the time resolution for kinetic studies of reactions with mass spectrometric detection is characterized in detail, and it shown how allows faster processes to be determined. The time‐resolved technique used pulsed laser photolysis initiate reaction a time‐of‐flight spectrometer (TOFMS) monitor progress, where reactant gas was sampled by sampling orifice photoionized using pulsed, vacuum ultraviolet light before being analyzed TOFMS. Characterization setup has been...
Infrared-vacuum ultraviolet double resonance experiments have been implemented in the ultracold environment provided by a Cinetique de Reaction en Ecoulement Supersonique Uniforme apparatus. With this technique rate coefficients of two kinds measured for rotational energy transfer collisions between CO and He: (a) those total removal from selected states J = 0, 1, 4, 6 vibronic state X 1Sigma+, v 2, (b) initial specific final states. Using different Laval nozzles, results obtained at several...
A balloon-borne system for tracking the sun both in elevation and azimuth is described. The weighs approximately 125 lb capable of ``pointing'' as much 20 payload at a predetermined position sky. Power requirements are w. An accuracy pointing ±15 min arc has been achieved. At some sacrifice simplicity, this could perhaps be improved to ±5 min. Results two flights, each attaining an altitude excess 100 000 ft, given.
The first excited electronic state of molecular oxygen, O2(a1Δg), is formed in the upper atmosphere by photolysis O3. Its lifetime over 70 min above 75 km, so that during day its concentration about 30 times greater than In order to explore potential reactivity with atmospheric constituents produced meteoric ablation, reactions Mg, Fe, and Ca O2(a) were studied a fast flow tube, where metal atoms either thermal evaporation (Ca Mg) or pulsed laser ablation target (Fe), detected induced...
Ab initio calculations, combined with experimental studies on the anaerobic hydrolysis of phosphaalkynes under thermal and photochemical conditions suggest a potential, exogenous source reduced oxidation state phosphorus for early Earth.
Abstract. We demonstrate a new instrument for in situ detection of atmospheric iodine atoms and molecules based on atomic molecular resonance off-resonance ultraviolet fluorescence excited by lamp emission. The combines the robustness, light weight, low power consumption efficient excitation radio-frequency discharge sources with high sensitivity photon counting technique. Calibration I2 is achieved via quantitative molecule Incoherent Broad Band Cavity-enhanced Absorption Spectroscopy....
Abstract. The lifetime of methane is controlled to a very large extent by the abundance OH radical. tropics are key region for removal, with oxidation in lower tropical troposphere dominating global removal budget (Bloss et al., 2005). In forested environments where biogenic VOC emissions high and NOx concentrations low, assumed be low due rapid reactions sink species such as isoprene. New, simultaneous measurements reactivity, k'OH, Borneo rainforest reported show much higher than...
Abstract. Fluorescence Assay by Gas Expansion (FAGE) has been used to detect ambient levels of OH and HO2 radicals at the Cape Verde Atmospheric Observatory, located in tropical Atlantic marine boundary layer, during May June 2007. Midday radical concentrations were high, with maximum 9×106 molecule cm−3 6×108 observed for HO2, respectively. A box model incorporating detailed Master Chemical Mechanism, extended include halogen chemistry, constrained all available measurements including...
Abstract. The design of a Highly Instrumented Reactor for Atmospheric Chemistry (HIRAC) is described and initial results obtained from HIRAC are presented. ability to perform in-situ laser-induced fluorescence detection OH HO2 radicals with the Fluorescence Assay by Gas Expansion (FAGE) technique establishes it as internationally unique chamber its size pressure/temperature variable capabilities. In addition FAGE technique, features suite analytical instrumentation, including: multipass FTIR...