In several recent field campaigns the existence of a strong daytime source nitrous acid was demonstrated. The mechanism this remains unclear. Accordingly, in present laboratory study, effect light (in range 300-500 nm) on uptake kinetics NO2 various surfaces taken as proxies for organic encountered troposphere (as aerosol but also ground surfaces) investigated. collaborative and product formation rate were measured by different flow tube reactors combination with sensitive HONO instrument....

This proposal involves direct photolysis processes occurring in the troposphere incorporating photochemical excitation and intermolecular energy transfer. The study of such could provide a better understanding ·OH radical formation pathways atmosphere consequence, more accurate prediction oxidative capacity atmosphere. Compounds that readily absorb tropospheric actinic window (ionic organic complexes, PAHs, aromatic carbonyl compounds) acting as potential photosensitizers atmospheric...

The uptake coefficients of NO2 on aqueous solutions containing guaiacol, syringol and catechol were determined over the pH range from 1 to 13 using wetted wall flowtube technique. measured used determine rate for reaction physically dissolved with neutral deprotonated forms phenolic compounds listed above. These organic are ubiquitous not only in biomass burning plumes but also soils, where they form part building blocks humic acids. kinetics or observed be strongly dependent increasing...

Hydroxyl radicals (OH) are known to control the oxidative capacity of atmosphere but their influence on reactivity within indoor environments is believed be little importance. Atmospheric direct sources OH include photolysis ozone and nitrous acid (HONO) ozonolysis alkenes. It has been argued that ultraviolet light fraction solar spectrum largely attenuated environments, thus, limiting extent photolytic sources. Conversely, alkenes suggested as main pathway formation settings. According this...

[1] The rate coefficient for the reaction of O(1D) with N2 at 295 K has been measured in three laboratories to be 3.1 × 10−11 cm3 molecule−1 s−1, an uncertainty 10% 95% confidence level, and 2.1 exp {(115 ± 10) /T} s−1 as a function temperature. (The quoted E/R will allow calculation constant various temperatures.) The implications this finding are decrease calculated OH production via H2O atmosphere by roughly 15% mid-troposphere above greatly reduce uncertainties HOx NOx rates atmosphere.

HCN profiles measured by solar occultation spectrometry during 10 balloon flights of the JPL MkIV instrument are presented. The reveal a compact correlation with stratospheric tracers. Calculations 2D‐model using established rate coefficients for reactions OH and O( 1 D) severely underestimate in middle upper stratosphere. use newly available these gives reasonable agreement modeled HCN. An yield ∼30% from reaction CH 3 CN is consistent measurements.

Our investigation focused on the efficacy of new nano-TiO 2 catalysts in consuming indoor volatile organic compounds (VOCs) when integrated into inorganic paint binders. A photocatalytic stability binders has also been studied.

This work focuses on the development and application of UV diffuse reflectance−laser flash photolysis technique to directly study kinetics reactions occurring at gas−liquid-phase boundary. The reaction Cl2•- radical anion with ethanol was chosen "probe" air−water surface. rates surface are shown be more rapid than in bulk liquid. Direct kinetic evidence is provided that least 2 times faster bulk. rate coefficient for + found (4.45 ± 0.80) × 105 M-1 s-1. For comparison, aqueous phase (1.77...

Flash photolysis (FP) coupled to resonance fluorescence (RF) was used measure the absolute rate coefficients (k1) for reaction of OH(X2Π) radicals with diiodomethane (CH2I2) over temperature range 295–374 K. The experiments involved time-resolved RF detection OH (A2Σ+ → X2Π transition at λ = 308 nm) following FP H2O/CH2I2/He mixtures. were produced by H2O in vacuum-UV wavelengths > 120 nm. Decays presence CH2I2 are observed be exponential, and decay rates found linearly dependent on...

Henry's law constants for acetone, 2-butanone, 2,3-butanedione, and isobutyraldehyde were investigated using a horizontal flow reactor coupled to molecular beam mass spectrometer. These organics belong class of oxygenated compounds that are increasingly used as industrial solvents chosen better understand evaluate their atmospheric fate. All experiments performed at pressure temperature over the range (275 298) K. The Hx T = 298 K following (in units M·atm-1): (26 ± 6); (2.7 0.3); (57 8);...

Flash photolysis (FP) coupled with resonance fluorescence (RF) was used to measure the absolute rate coefficients for reactions of OH(X(2)Π) radicals C(2)H(5)I (k(1)), n-C(3)H(7)I (k(2)), and iso-C(3)H(7)I (k(3)) at temperatures between 297 372 K in 188 Torr He; this represents first temperature-dependent kinetics studies title reactions. The experiments involved time-resolved RF detection OH (A(2)Σ(+) → X(2)Π transition λ = 308 nm) following FP H(2)O/C(2)H(5)I/He, H(2)O/n-C(3)H(7)I/He,...

A flash photolysis-resonance fluorescence (FP-RF) technique was employed to study the kinetics and mechanism of reaction OH radicals with p-cymene at temperatures between 297 413 K in helium buffer gas. FP-RF experiments involved time-resolved detection by RF following vacuum-UV photolysis H2O–p-cymene–He H2O–He mixtures. Biexponential functions were fitted decays according reversible addition form a single adduct. rate constant (15.7 ± 1.1) × 10−12 is obtained (in units cm3 s−1) room...

A laser flash photolysis–resonance fluorescence technique has been employed to investigate the kinetics of reactions electronically excited oxygen atoms, O(1D2), with N2 (k1) and O2 (k2) as a function temperature (197–427 K) in helium buffer gas at pressures 11–40 Torr. The results are well-described by following Arrhenius expressions (units 10−11 cm3 molecule−1 s−1): k1(T) = (1.99 ± 0.06) exp{(145 9)/T} k2(T) (3.39 0.03) exp{(63 3)/T}. Uncertainties parameters 2σ represent precision only;...

Abstract A flash photolysis resonance fluorescence technique has been employed to investigate the kinetics and mechanism of reaction OH(X 2 Π) radicals with CH 3 I over temperature pressure ranges 295–390 K 82–303 Torr He, respectively. The experiments involved time‐resolved RF detection OH (A Σ + → X Π transition at λ = 308 nm) following FP H O/CH I/He mixtures. were produced by O in vacuum‐UV wavelengths > 115 nm using a commercial Perkin‐Elmer Xe lamp. Decays presence are observed be...

Bimolecular rate coefficients for the reactions of hydroxyl radical, OH, with methanol, ethanol, tetrahydrofuran, dimethylmalonate [CH3OC(O)CH2C(O)OCH3], dimethylsuccinate [CH3OC(O)CH2CH2C(O)OCH3], dimethylcarbonate [CH3OC(O)OCH3] and diethylcarbonate [CH3CH2OC(O)OCH2CH3] in aqueous solutions have been measured using a novel experimental approach. The centrepiece new technique reported this work is Teflon AF 2400 liquid core waveguide. physical properties waveguide allow construction...

The rate coefficient for the reaction of O( 1 D) with N 2 at 295 K has been measured in three laboratories to be 3.1 × 10 −11 cm 3 molecule −1 s , an uncertainty 10% 95% confidence level, and 2.1 exp {(115 ± 10) /T} as a function temperature. (The quoted E/R will allow calculation constant various temperatures.) implications this finding are decrease calculated OH production via H O atmosphere by roughly 15% mid‐troposphere above greatly reduce uncertainties HO x NO rates atmosphere.