Direct Detection of OH Radicals and Indirect Detection of H2O2 Molecules in the Gas Phase near a TiO2 Photocatalyst Using LIF

2008 ◽  
Vol 112 (25) ◽  
pp. 9115-9119 ◽  
Author(s):  
Guillaume Vincent ◽  
Alina Aluculesei ◽  
Alexander Parker ◽  
Christa Fittschen ◽  
Orfan Zahraa ◽  
...  
Keyword(s):  
Gas Phase ◽  
Direct Detection ◽  
Indirect Detection ◽  
Oh Radicals ◽  
Tio2 Photocatalyst

scholarly journals Measurements of OH and HO<sub>2</sub> yields from the gas phase ozonolysis of isoprene

2010 ◽  
Vol 10 (3) ◽  
pp. 1441-1459 ◽  
Author(s):  
T. L. Malkin ◽  
A. Goddard ◽  
D. E. Heard ◽  
P. W. Seakins
Keyword(s):  
Gas Phase ◽  
Atmospheric Pressure ◽  
Room Temperature ◽  
Recent Literature ◽  
Direct Detection ◽  
Kinetic Method ◽  
Oh Radicals ◽  
First Order ◽  
Gas Expansion ◽  
First Time

Abstract. The reactions of ozone with alkenes are an important source of hydroxyl (OH) radicals; however, quantification of their importance is hindered by uncertainties in the absolute OH yield. Hydroxyl radical yields for the gas-phase ozonolysis of isoprene are determined in this paper by four different methods: (1) The use of cyclohexane as an OH scavenger, and the production of cyclohexanone, (2) The use of 1,3,5-trimethylbenzene as an OH tracer, and the diminution in its concentration, (3) A kinetic method in which the OH yield was obtained by performing a series of pseudo-first-order experiments in the presence or absence of an OH scavenger (cyclohexane), (4) The OH and HO2 yields were determined by fitting the temporal OH and HO2 profiles following direct detection of absolute OH and HO2 concentrations by laser induced fluorescence at low pressure (Fluorescence Assay by Gas Expansion- FAGE). The following OH yields for the ozonolysis of isoprene were obtained, relative to alkene consumed, for each method: (1) Scavenger (0.25±0.04), (2) Tracer (0.25±0.03), (3) Kinetic study (0.27±0.02), and (4) Direct observation (0.26±0.02), the error being one standard deviation. An averaged OH yield of 0.26±0.02 is recommended at room temperature and atmospheric pressure and this result is compared with recent literature determinations. The HO2 yield was directly determined for the first time using FAGE to be 0.26±0.03.

scholarly journals Measurements of OH and HO<sub>2</sub> yields from the gas phase ozonolysis of isoprene

2009 ◽  
Vol 9 (4) ◽  
pp. 17579-17631 ◽  
Author(s):  
T. L. Malkin ◽  
A. Goddard ◽  
D. E. Heard ◽  
P. W. Seakins
Keyword(s):  
Gas Phase ◽  
Atmospheric Pressure ◽  
Room Temperature ◽  
Recent Literature ◽  
Direct Detection ◽  
Kinetic Method ◽  
Oh Radicals ◽  
First Order ◽  
Gas Expansion ◽  
First Time

Abstract. The reactions of ozone with alkenes are an important source of hydroxyl (OH) radicals; however, quantification of their importance is hindered by uncertainties in the absolute OH yield. Hydroxyl radical yields for the gas-phase ozonolysis of isoprene are determined in this paper by four different methods: (1) The use of cyclohexane as an OH scavenger, and the production of cyclohexanone, (2) The use of 1,3,5-trimethylbenzene as an OH tracer, and the diminution in its concentration, (3) A kinetic method in which the OH yield was obtained by performing a series of pseudo-first-order experiments in the presence or absence of an OH scavenger (cyclohexane), (4) The OH and HO2 yields were determined by fitting the temporal OH and HO2 profiles following direct detection of absolute OH and HO2 concentrations by laser induced fluorescence at low pressure (Fluorescence Assay by Gas Expansion-FAGE). The following OH yields for the ozonolysis of isoprene were obtained, relative to alkene consumed, for each method: (1) Scavenger (0.25 ± 0.04), (2) Tracer (0.25 ± 0.03), (3) Kinetic study (0.27 ± 0.02), and (4) Direct observation (0.26 ± 0.02), the error being one standard deviation. An averaged OH yield of 0.26 ± 0.02 is recommended at room temperature and atmospheric pressure and this result is compared with recent literature determinations. The HO2 yield was directly determined for the first time using FAGE to be 0.26 ± 0.03.

scholarly journals Effective field theory analysis of dark matter-standard model interactions with spin one mediators

2021 ◽  
Vol 2021 (2) ◽  
Author(s):  
Fabiola Fortuna ◽  
Pablo Roig ◽  
José Wudka
Keyword(s):  
Field Theory ◽  
Dark Matter ◽  
Standard Model ◽  
Effective Field Theory ◽  
Gamma Ray ◽  
Direct Detection ◽  
Effective Field ◽  
Indirect Detection ◽  
Theory Analysis ◽  
Invisible Decay

Abstract We analyze interactions between dark matter and standard model particles with spin one mediators in an effective field theory framework. In this paper, we are considering dark particles masses in the range from a few MeV to the mass of the Z boson. We use bounds from different experiments: Z invisible decay width, relic density, direct detection experiments, and indirect detection limits from the search of gamma-ray emissions and positron fluxes. We obtain solutions corresponding to operators with antisymmetric tensor mediators that fulfill all those requirements within our approach.

scholarly journals DARK MATTER DYNAMICS AND INDIRECT DETECTION

2005 ◽  
Vol 20 (14) ◽  
pp. 1021-1036 ◽  
Author(s):  
GIANFRANCO BERTONE ◽  
DAVID MERRITT
Keyword(s):  
Dark Matter ◽  
Total Mass ◽  
Galactic Center ◽  
Direct Detection ◽  
Indirect Detection ◽  
Matter Distribution ◽  
Dark Matter Distribution ◽  
Particle Dark Matter ◽  
The Universe ◽  
Rule Out

Non-baryonic, or "dark", matter is believed to be a major component of the total mass budget of the Universe. We review the candidates for particle dark matter and discuss the prospects for direct detection (via interaction of dark matter particles with laboratory detectors) and indirect detection (via observations of the products of dark matter self-annihilations), focusing in particular on the Galactic center, which is among the most promising targets for indirect detection studies. The gravitational potential at the Galactic center is dominated by stars and by the supermassive black hole, and the dark matter distribution is expected to evolve on sub-parsec scales due to interaction with these components. We discuss the dominant interaction mechanisms and show how they can be used to rule out certain extreme models for the dark matter distribution, thus increasing the information that can be gleaned from indirect detection searches.

Atmospheric chemistry of trans-CF3CHCHCl: Kinetics of the gas-phase reactions with Cl atoms, OH radicals, and O3

2008 ◽  
Vol 199 (1) ◽  
pp. 92-97 ◽  
Author(s):  
M.P. Sulbaek Andersen ◽  
E.J.K. Nilsson ◽  
O.J. Nielsen ◽  
M.S. Johnson ◽  
M.D. Hurley ◽  
...  
Keyword(s):  
Gas Phase ◽  
Atmospheric Chemistry ◽  
Oh Radicals ◽  
Gas Phase Reactions ◽  
Kinetics Of ◽  
Cl Atoms
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