The Experts below are selected from a list of 114 Experts worldwide ranked by ideXlab platform
I. I. Morozov - One of the best experts on this subject based on the ideXlab platform.
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Experimental simulation of stratospheric ozone reactions with chloroalkane organic pollutants
Environmental Chemistry, 2021Co-Authors: Serguei V. Savilov, N. E. Strokova, Anton S. Ivanov, I. I. MorozovAbstract:Environmental context Chlorinated organic atmospheric pollutants, which can be produced naturally or anthropogenically, are considered as a factor responsible for stratospheric ozone depletion. Based on experimental simulations and low temperature vibrational spectroscopy, this work reports a mechanism for the reaction of chloroalkanes with ozone. This reaction leads to the formation of the photochemically reactive Chlorine Oxide species. Kinetics and implications of the reactions are discussed. Abstract The present work deals with the important problem of stratospheric ozone depletion and an investigation of the atmospheric decay of organic pollutants. The products of the heterogeneous reactions of ozone with chloroethane and 1-chloropropane in a flow-through vacuum electric discharge unit under conditions similar those observed in the stratosphere are studied by low-temperature infrared (IR) absorption spectroscopy. Taking into account the literature data, a scheme for the interaction of ozone with halogen-substituted alkanes at low temperatures is proposed, which shows the formation of Chlorine Oxides that have high photochemical activity and can cause damage to the ozone layer even when present in small concentrations. The conversion of chloroalkanes over time demonstrates the first-order-decay behaviour of the investigated processes.
Helge Willner - One of the best experts on this subject based on the ideXlab platform.
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Chlorine Oxide radicals clox x 1 4 studied by matrix isolation spectroscopy
Chemistry: A European Journal, 2002Co-Authors: Rodion Kopitzky, Hinrich Grothe, Helge WillnerAbstract:Low pressure flash thermolysis of different precursor molecules containing-ClO, -ClO3 or -OClO3 yield, when highly diluted in Ne or O2 and subsequent quenching of the products in a matrix at 5 or 15 K, ClOx (x = 1, 3, 4) radicals, respectively. If Ne or O2 gas is directed over solid ClO2 at -120 degrees C and the resulting gas mixtures are immediately deposited as a matrix, a high fraction of (OClO)2 is trapped. This enables recording of IR and UV spectra of weakly bonded (OClO)2 dimers and detailed studying of their photochemistry. For Ne or O2 matrix isolated ClO radicals the vibrational wavenumbers and electronic transitions are only slightly affected compared with the gas phase. In this study strong evidence is found for long lived ClO in the electronically excited 2 [symbol: see text] 1/2 state. A comprehensive IR study of Ne matrix isolated ClO3 (fundamentals at 1081, 905, 567, 476 cm-1) yield i) a reliable force field; ii) a OClO bond angle of alpha e = 113.8 +/- 1 degrees and iii) a ClO bond length of 148.5 +/- 2 pm in agreement with predicted data from quantum chemical calculations. The UV/Vis spectrum of ClO3 isolated in a Ne matrix (lambda max at 32,100 and 23,150 cm-1) agrees well with the photoelectron spectrum of ClO3- and theoretical predictions. The origin of the structured high energy absorption is at 22,696 cm-1 and three fundamentals (794, 498, 280 cm-1) are detected in the C2E state. By photolysis of ClO3 with visible light the complex ClO.O2 with ClO in the 2 [symbol: see text] 1/2 state is formed. In an extended spectroscopic study of the elusive ClO4 radical, isolated in a Ne or O2 matrix, three additional IR bands, a complete UV spectrum and a strong interaction with O2 are found. This leads to the conclusion that ClO4 exhibits C2v or Cs symmetry with a shallow potential minimum and forms with O2 the previously unknown peroxy radical O3ClO-O2. All these results are discussed in the context of recent developments in the chemistry and spectroscopy of the important and interesting ClOx (x = 1-4) family of radicals.
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Chlorine Oxide radicals ClOx (x = 1-4) studied by matrix isolation spectroscopy.
Chemistry (Weinheim an der Bergstrasse Germany), 2002Co-Authors: Rodion Kopitzky, Hinrich Grothe, Helge WillnerAbstract:Low pressure flash thermolysis of different precursor molecules containing-ClO, -ClO3 or -OClO3 yield, when highly diluted in Ne or O2 and subsequent quenching of the products in a matrix at 5 or 15 K, ClOx (x = 1, 3, 4) radicals, respectively. If Ne or O2 gas is directed over solid ClO2 at -120 degrees C and the resulting gas mixtures are immediately deposited as a matrix, a high fraction of (OClO)2 is trapped. This enables recording of IR and UV spectra of weakly bonded (OClO)2 dimers and detailed studying of their photochemistry. For Ne or O2 matrix isolated ClO radicals the vibrational wavenumbers and electronic transitions are only slightly affected compared with the gas phase. In this study strong evidence is found for long lived ClO in the electronically excited 2 [symbol: see text] 1/2 state. A comprehensive IR study of Ne matrix isolated ClO3 (fundamentals at 1081, 905, 567, 476 cm-1) yield i) a reliable force field; ii) a OClO bond angle of alpha e = 113.8 +/- 1 degrees and iii) a ClO bond length of 148.5 +/- 2 pm in agreement with predicted data from quantum chemical calculations. The UV/Vis spectrum of ClO3 isolated in a Ne matrix (lambda max at 32,100 and 23,150 cm-1) agrees well with the photoelectron spectrum of ClO3- and theoretical predictions. The origin of the structured high energy absorption is at 22,696 cm-1 and three fundamentals (794, 498, 280 cm-1) are detected in the C2E state. By photolysis of ClO3 with visible light the complex ClO.O2 with ClO in the 2 [symbol: see text] 1/2 state is formed. In an extended spectroscopic study of the elusive ClO4 radical, isolated in a Ne or O2 matrix, three additional IR bands, a complete UV spectrum and a strong interaction with O2 are found. This leads to the conclusion that ClO4 exhibits C2v or Cs symmetry with a shallow potential minimum and forms with O2 the previously unknown peroxy radical O3ClO-O2. All these results are discussed in the context of recent developments in the chemistry and spectroscopy of the important and interesting ClOx (x = 1-4) family of radicals.
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Synthesis and properties of chloryl chloride, ClCLO2
Inorganic Chemistry, 1992Co-Authors: Holger S. P. Mueller, Helge WillnerAbstract:Halogene exchange between FClO 2 and AlCl 3 , BCl 3 , or HCl afforded chloryl chloride, ClClO 2 , identified by IR and UV spectroscopy in noble gas matrices and in the gas phase. All six fundamental vibrations, as well as some over and combination tones of 12 isotopomcrs were detected for the novel Chlorine Oxide having C, symmetry
Serguei V. Savilov - One of the best experts on this subject based on the ideXlab platform.
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Experimental simulation of stratospheric ozone reactions with chloroalkane organic pollutants
Environmental Chemistry, 2021Co-Authors: Serguei V. Savilov, N. E. Strokova, Anton S. Ivanov, I. I. MorozovAbstract:Environmental context Chlorinated organic atmospheric pollutants, which can be produced naturally or anthropogenically, are considered as a factor responsible for stratospheric ozone depletion. Based on experimental simulations and low temperature vibrational spectroscopy, this work reports a mechanism for the reaction of chloroalkanes with ozone. This reaction leads to the formation of the photochemically reactive Chlorine Oxide species. Kinetics and implications of the reactions are discussed. Abstract The present work deals with the important problem of stratospheric ozone depletion and an investigation of the atmospheric decay of organic pollutants. The products of the heterogeneous reactions of ozone with chloroethane and 1-chloropropane in a flow-through vacuum electric discharge unit under conditions similar those observed in the stratosphere are studied by low-temperature infrared (IR) absorption spectroscopy. Taking into account the literature data, a scheme for the interaction of ozone with halogen-substituted alkanes at low temperatures is proposed, which shows the formation of Chlorine Oxides that have high photochemical activity and can cause damage to the ozone layer even when present in small concentrations. The conversion of chloroalkanes over time demonstrates the first-order-decay behaviour of the investigated processes.
Laisheng Wang - One of the best experts on this subject based on the ideXlab platform.
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the electronic structure and electron affinities of higher Chlorine Oxide radicals clox x 2 4 from photoelectron spectroscopy of clox anions
Journal of Chemical Physics, 2000Co-Authors: Xuebin Wang, Laisheng WangAbstract:The electronic structure of ClOx (x=2–4) radicals were experimentally investigated using anion photoelectron spectroscopy of the respective anions at several photon energies. The electron affinities of ClO3 and ClO4 were obtained for the first time and were found to be very high, 4.25±0.10 and 5.25±0.10 eV, respectively. Three low-lying excited states were observed for ClO2 with excitation energies of 2.10 eV (2B2), ∼2.60 eV (2A1 and 2A2). The 2A1 and 2A2 states were found to be nearly degenerate. Two low-lying states were observed for ClO3 at ∼1.20 eV (2A2) and ∼2.65 eV (2E), whereas no excited state was observed for ClO4 even at our highest photon energy of 157 nm (7.866 eV). The photoelectron spectra were assigned and compared with available theoretical calculations. The excellent agreement between the experimental and theoretical results confirmed the previous calculations.
James G. Anderson - One of the best experts on this subject based on the ideXlab platform.
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The performance of a new instrument for in situ measurements of ClO in the lower stratosphere
Geophysical Research Letters, 1993Co-Authors: Darin W. Toohey, Linnea M. Avallone, Norton Allen, J. N. Demusz, J. N. Hazen, N. L. Hazen, James G. AndersonAbstract:Abundances of Chlorine Oxide (ClO) have been measured from 16 km to 30 km by a new balloon-borne in situ instrument developed from an optical design flown previously on the NASA ER-2 aircraft. This instrument, a prototype for one to be flown on the Perseus remotely piloted aircraft, was one-third the weight of that on the ER-2, yet retained the high precision and accuracy necessary for detailed photochemical studies of the lower stratosphere. In this paper we discuss the performance of the instrument during its first flight on March 31, 1991 over eastern New Mexico.