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Philip H. Taylor - One of the best experts on this subject based on the ideXlab platform.
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Rate Coefficients and Mechanistic Analysis for the Reaction of Hydroxyl Radicals with 1,1-Dichloroethylene and trans-1,2-Dichloroethylene over an Extended Temperature Range
The Journal of Physical Chemistry A, 2001Co-Authors: Takahiro Yamada, Philip H. Taylor, Abdulaziz El-sinawi, And Masud Siraj, Jingping Peng, Paul MarshallAbstract:Rate coefficients are reported for the gas-phase reaction of the hydroxyl radical (OH) with 1,1-dichloroethylene (k1) and trans-1,2-dichloroethylene (k2) over an Extended Temperature Range at 740 ± 10 Torr in a He bath gas. Absolute rate measurements were obtained using a laser photolysis/laser-induced fluorescence (LP/LIF) technique under slow flow conditions. Rate measurements for k1 exhibited complex behavior with negative Temperature dependence at Temperatures below 640 K, a rapid falloff in rate between 650 and 700 K, and positive Temperature dependence from 700 to 750 K. The simple Arrhenius equation adequately describes the data below 640 K and above 700 K and is given (in units of cm3 molecule-1 s-1) by k1(291−640 K) = (1.81 ± 0.36) × 10-12 exp(511 ± 71)/T and k1(700−750 K) = 3.13 × 10-10 exp(−5176/T). Rate measurements for k2 also exhibited complex behavior with a near-zero or slightly negative Temperature dependence below 500 K and a near-zero or slightly positive Temperature dependence above 50...
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KINETICS OF THE REACTION OF OH RADICALS WITH CH2CLCF2CL AND CH2CLCF3 OVER AN Extended Temperature Range
The Journal of Physical Chemistry A, 1999Co-Authors: Tunchen D. Fang, Philip H. Taylor, Rajiv BerryAbstract:The fate of anthropogenic halogenated hydrocarbons that are released to the atmosphere in the course of various industrial or technological activities is of great environmental concern. In addition to their well-known connection to stratospheric ozone destruction, these compounds are effective greenhouse gases. Rate coefficients are reported for the gas-phase reaction of hydroxyl (OH) radicals with CH{sub 2}ClCF{sub 2}Cl ({kappa}{sub 1}) and CH{sub 2}ClCF{sub 3} ({Kappa}{sub 2}) over an Extended Temperature Range. The measurements were performed using a laser photolysis/laser-induced fluorescence (PLP/LIF) technique under slow flow conditions at a total pressure of 740 {+-} 10 Torr. The lower Temperature measurements for {kappa}{sub 1} where in agreement with previous measurements using different techniques. Prior measurements for {kappa}{sub 2} using different techniques exhibit significant scatter. The new lower Temperature data reported here lie intermediate to the previous measurements. Arrhenius plots of the data exhibit significant curvature and were fit to the expression {kappa}(T) = AT{sup B} exp({minus}C/T). A semiempirical fitting approach was used in which A and B were obtained from transition-state theory (TST) and C was determined from a nonlinear least-squares fit to the experimental data. Ab initio calculations were used to evaluate the thermochemical properties of the activated complex.
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Kinetics of the OH + CH3CF2Cl Reaction over an Extended Temperature Range
The Journal of Physical Chemistry A, 1997Co-Authors: Tunchen D. Fang, Philip H. Taylor, Barry Dellinger, Chris J. Ehlers, Rajiv BerryAbstract:Rate coefficients of the reaction of hydroxyl (OH) radicals with CH3CF2Cl over an Extended Temperature Range are reported. Measurements were performed using a laser photolysis/laser-induced fluorescence technique under slow flow conditions at a total pressure of 740 ( 10 Torr. Arrhenius plots of the data exhibited significant curvature and were fitted to the form of k(T) ) ATB exp(-C/T). A semiempirical fitting approach was used in which A and B were obtained from transition state theory (TST) and C was determined from a nonlinear least-squares fit to the experimental data. Ab initio calculations were used to reveal the thermochemical properties of the activated complex. The resulting modified Arrhenius expression was k(295-808 K) ) (1.20 ( 0.32) × 10-17 T1.89(0.05 exp[(-1541 ( 128)/T] cm3 molecule-1 s-1. This semiempirical fit is shown to be superior to a purely empirical fit to the data. The expression was in good agreement with experimental results and previous experimental studies between Temperatures of 240 and 480 K. The TST-based modified Arrhenius expression is compared to previous TST and structure-activity relationship predictions.
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Rate Coefficients of Hydroxyl Radical Reaction with Dimethyl Ether and Methyl tert-Butyl Ether over an Extended Temperature Range
The Journal of Physical Chemistry A, 1997Co-Authors: Muhammad Arif, Barry Dellinger, Philip H. TaylorAbstract:Rate coefficients of the reaction of hydroxyl (OH) radicals with CH3OCH3 (k1) and CH3OC(CH3)3 (k2) over an Extended Temperature Range are reported. Measurements were performed using a laser photolysis−laser-induced fluorescence technique under slow flow conditions at a total pressure of 740 ± 10 Torr. Arrhenius plots of the data exhibited significant curvature and were fitted in the form of k(T) = ATB exp(−C/T). The resulting modified Arrhenius expressions (error limits ±2σ) that best described these Extended Temperature measurements and prior low-Temperature measurements were (in units of cm3 molecule-1 s-1) k1(295−650 K) = (1.05 ± 0.10) × 10-17T2.0 exp[(328 ± 32)/T] and k2(293−750 K) = (1.15 ± 0.11) × 10-17T2.04 exp[(266 ± 41)/T]. Comparison of our measurements for k1 with previous, overlapping low-Temperature measurements indicated generally good agreement. Our measurements for k2, although consistent with previous room Temperature measurements, exhibited a larger Temperature dependence than previously...
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ABSOLUTE RATE MEASUREMENTS OF THE REACTION OF OH RADICALS WITH HCFC-21 (CHFCL2) AND HCFC-22 (CHF2CL) OVER AN Extended Temperature Range
The Journal of Physical Chemistry, 1996Co-Authors: Tunchen D. Fang, Philip H. Taylor, Barry DellingerAbstract:Rate coefficients of the reaction of hydroxyl (OH) radicals with CHFCl2 (k1) and CHF2Cl (k2) over an Extended Temperature Range are reported. Measurements were performed using a laser photolysis−laser-induced fluorescence (LP/LIF) technique under slow flow conditions at a total pressure of 740 ± 10 Torr. Arrhenius plots of the data exhibited significant curvature and were fitted in the form of k(T) = ATB exp(−C/T). A semiempirical fitting approach was used in which A and B were obtained from a transition state theory (TST) calculation and C was determined from a nonlinear least squares fit to the experimental data. The resulting modified Arrhenius expressions were k1(T) = (3.13 ± 0.2) × 10-18 T1.93±0.01 exp[(−552 ± 18)/T] cm3 molecule-1 s-1 and k2(T) = (3.10 ± 0.2) × 10-18 T1.94±0.01 exp[(−1112 ± 26)/T)] cm3 molecule-1 s-1. This semiempirical fit is shown to be superior to a purely empirical fit to the data. The expressions for k1 and k2 are in good agreement with the previous studies between Temperatures...
Luís Paulo N. Rebelo - One of the best experts on this subject based on the ideXlab platform.
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viscosity of c2 c14 1 alkyl 3 methylimidazolium bis trifluoromethylsulfonyl amide ionic liquids in an Extended Temperature Range
Fluid Phase Equilibria, 2011Co-Authors: Mohammad Tariq, Pedro J. Carvalho, João A. P. Coutinho, Isabel M. Marrucho, Jose Canongia N Lopes, Luís Paulo N. RebeloAbstract:Abstract Dynamic viscosities of several members of the 1-alkyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide, [Cnmim][NTf2], ionic liquids family, with the cation alkyl side-chain length varying from 2 to 14 carbon atoms, have been measured in the 278.15 K to 393.15 K Temperature Range using two different apparatuses. To the best of our knowledge, it is the first time that such an extensive assessment of viscosity – in terms of the number of compounds of a single ionic liquid homologous series, of the broad Range of Temperature covered, and the use of two different experimental techniques – is reported. The use of two different instruments, using different methodologies, provides information about the uncertainties in the measurement of viscosity of ionic liquids, including its dependence on the presence of traces of water and other impurities. An extensive critical analysis of the deviations between the data measured in this work and those reported in literature has been carried out.
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Viscosity of (C2–C14) 1-alkyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide ionic liquids in an Extended Temperature Range
Fluid Phase Equilibria, 2011Co-Authors: Mohammad Tariq, Pedro J. Carvalho, João A. P. Coutinho, Isabel M. Marrucho, José N. Canongia Lopes, Luís Paulo N. RebeloAbstract:Abstract Dynamic viscosities of several members of the 1-alkyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide, [Cnmim][NTf2], ionic liquids family, with the cation alkyl side-chain length varying from 2 to 14 carbon atoms, have been measured in the 278.15 K to 393.15 K Temperature Range using two different apparatuses. To the best of our knowledge, it is the first time that such an extensive assessment of viscosity – in terms of the number of compounds of a single ionic liquid homologous series, of the broad Range of Temperature covered, and the use of two different experimental techniques – is reported. The use of two different instruments, using different methodologies, provides information about the uncertainties in the measurement of viscosity of ionic liquids, including its dependence on the presence of traces of water and other impurities. An extensive critical analysis of the deviations between the data measured in this work and those reported in literature has been carried out.
Michel Jean Rossi - One of the best experts on this subject based on the ideXlab platform.
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The Kinetics of the Reaction C2H5• + HI → C2H6 + I• over an Extended Temperature Range (213 - 623 K): Experiment and Modeling
Zeitschrift für Physikalische Chemie, 2015Co-Authors: Nicholas Leplat, Jozef Federic, Katarina Sulkova, Maria Sudolska, Florent Louis, Ivan Cernusak, Michel Jean RossiAbstract:The present study reports Temperature dependent rate constants k1 for the title reaction across the Temperature Range 213 to 293 K obtained in a Knudsen flow reactor equipped with an external free radical source based on the reaction C2H5I + H• → C2H5• + HI and single VUV-photon ionization mass spectrometry using Lyman-α radiation of 10.2 eV. Combined with previously obtained high-Temperature data of k1 in the Range 298–623 K using the identical experimental equipment and based on the kinetics of C2H5• disappearance with increasing HI concentration we arrive at the following Temperature dependence best described by a three-parameter fit to the combined data set: k1 = (1.89 ± 1.19)10−13(T/298)2.92±0.51 exp ((3570 ± 1500)/RT), R = 8.314 J mol–1 K–1 in the Range 213–623 K. The present results confirm the general properties of kinetic data obtained either in static or Knudsen flow reactors and do nothing to reconcile the significant body of data obtained in laminar flow reactors using photolytic free radical generation and suitable free radical precursors. The resulting rate constant for wall-catalyzed disappearance of ethyl radical across the full Temperature Range is discussed. Highly correlated ab initio quantum chemistry methods and canonical transition state theory were applied for the reaction energy profiles and rate constants. Geometry optimizations of reactants, products, molecular complexes, and transition states are determined at the CCSD/cc-pVDZ level of theory. Subsequent single-point energy calculations employed the DK-CCSD(T)/ANO-RCC level. Further improvement of electronic energies has been achieved by applying spin-orbit coupling corrections towards full configuration interaction and hindered rotation analysis of vibrational contributions. The resulting theoretical rate constants in the Temperature Range 213–623 K lie in the Range E-11–E-12 cm3 molecule–1 s–1, however experiments and theoretical modelling seem at great odds with each other.
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The Kinetics of the Reaction C2H5• + HI → C2H6 + I• over an Extended Temperature Range (213–623 K): Experiment and Modeling
Zeitschrift für Physikalische Chemie, 2015Co-Authors: Nicholas Leplat, Jozef Federic, Katarina Sulkova, Maria Sudolska, Florent Louis, Ivan Černušák, Michel Jean RossiAbstract:AbstractThe present study reports Temperature dependent rate constantsHighly correlated
Barry Dellinger - One of the best experts on this subject based on the ideXlab platform.
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Kinetics of the OH + CH3CF2Cl Reaction over an Extended Temperature Range
The Journal of Physical Chemistry A, 1997Co-Authors: Tunchen D. Fang, Philip H. Taylor, Barry Dellinger, Chris J. Ehlers, Rajiv BerryAbstract:Rate coefficients of the reaction of hydroxyl (OH) radicals with CH3CF2Cl over an Extended Temperature Range are reported. Measurements were performed using a laser photolysis/laser-induced fluorescence technique under slow flow conditions at a total pressure of 740 ( 10 Torr. Arrhenius plots of the data exhibited significant curvature and were fitted to the form of k(T) ) ATB exp(-C/T). A semiempirical fitting approach was used in which A and B were obtained from transition state theory (TST) and C was determined from a nonlinear least-squares fit to the experimental data. Ab initio calculations were used to reveal the thermochemical properties of the activated complex. The resulting modified Arrhenius expression was k(295-808 K) ) (1.20 ( 0.32) × 10-17 T1.89(0.05 exp[(-1541 ( 128)/T] cm3 molecule-1 s-1. This semiempirical fit is shown to be superior to a purely empirical fit to the data. The expression was in good agreement with experimental results and previous experimental studies between Temperatures of 240 and 480 K. The TST-based modified Arrhenius expression is compared to previous TST and structure-activity relationship predictions.
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Rate Coefficients of Hydroxyl Radical Reaction with Dimethyl Ether and Methyl tert-Butyl Ether over an Extended Temperature Range
The Journal of Physical Chemistry A, 1997Co-Authors: Muhammad Arif, Barry Dellinger, Philip H. TaylorAbstract:Rate coefficients of the reaction of hydroxyl (OH) radicals with CH3OCH3 (k1) and CH3OC(CH3)3 (k2) over an Extended Temperature Range are reported. Measurements were performed using a laser photolysis−laser-induced fluorescence technique under slow flow conditions at a total pressure of 740 ± 10 Torr. Arrhenius plots of the data exhibited significant curvature and were fitted in the form of k(T) = ATB exp(−C/T). The resulting modified Arrhenius expressions (error limits ±2σ) that best described these Extended Temperature measurements and prior low-Temperature measurements were (in units of cm3 molecule-1 s-1) k1(295−650 K) = (1.05 ± 0.10) × 10-17T2.0 exp[(328 ± 32)/T] and k2(293−750 K) = (1.15 ± 0.11) × 10-17T2.04 exp[(266 ± 41)/T]. Comparison of our measurements for k1 with previous, overlapping low-Temperature measurements indicated generally good agreement. Our measurements for k2, although consistent with previous room Temperature measurements, exhibited a larger Temperature dependence than previously...
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ABSOLUTE RATE MEASUREMENTS OF THE REACTION OF OH RADICALS WITH HCFC-21 (CHFCL2) AND HCFC-22 (CHF2CL) OVER AN Extended Temperature Range
The Journal of Physical Chemistry, 1996Co-Authors: Tunchen D. Fang, Philip H. Taylor, Barry DellingerAbstract:Rate coefficients of the reaction of hydroxyl (OH) radicals with CHFCl2 (k1) and CHF2Cl (k2) over an Extended Temperature Range are reported. Measurements were performed using a laser photolysis−laser-induced fluorescence (LP/LIF) technique under slow flow conditions at a total pressure of 740 ± 10 Torr. Arrhenius plots of the data exhibited significant curvature and were fitted in the form of k(T) = ATB exp(−C/T). A semiempirical fitting approach was used in which A and B were obtained from a transition state theory (TST) calculation and C was determined from a nonlinear least squares fit to the experimental data. The resulting modified Arrhenius expressions were k1(T) = (3.13 ± 0.2) × 10-18 T1.93±0.01 exp[(−552 ± 18)/T] cm3 molecule-1 s-1 and k2(T) = (3.10 ± 0.2) × 10-18 T1.94±0.01 exp[(−1112 ± 26)/T)] cm3 molecule-1 s-1. This semiempirical fit is shown to be superior to a purely empirical fit to the data. The expressions for k1 and k2 are in good agreement with the previous studies between Temperatures...
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laser photolysis laser induced fluorescence studies of the reaction of hydroxyl with 1 1 1 2 and 1 1 2 2 tetrachloroethane over an Extended Temperature Range
The Journal of Physical Chemistry, 1993Co-Authors: Zhen Jiang, Philip H. Taylor, Barry DellingerAbstract:Absolute rate coefficients are reported for the gas-phase reaction of OH radicals with 1,1,1,2-(k 1 ) and 1, 1,2,2-tetrachloroethane (k 2 ) over an Extended Temperature Range. Employing a laser photolysis/laser-induced fluorescence technique, experiments were conducted with a flow system at a total pressure of 740±10 Torr using He as diluent and carrier gas. The Temperature dependence of the rate coefficients was best described by the modified Arrhenius expressions k 1 (293-882 K)=(3.36±0.52)×10 -12 (T/300) 1.21 exp[(-1553±92)/T] cm 3 molecule -1 s -1 and k 2 (295-701 K)=(2.72±0.42)×10 -12 (T/300) 0.22 exp[(-915±62)/T] cm 3 molec -1 s -1
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Laser photolysis/laser-induced fluorescence studies of the reaction of hydroxyl with 1,1,1,2- and 1,1,2,2-tetrachloroethane over an Extended Temperature Range
The Journal of Physical Chemistry, 1993Co-Authors: Zhen Jiang, Philip H. Taylor, Barry DellingerAbstract:Absolute rate coefficients are reported for the gas-phase reaction of OH radicals with 1,1,1,2-(k 1 ) and 1, 1,2,2-tetrachloroethane (k 2 ) over an Extended Temperature Range. Employing a laser photolysis/laser-induced fluorescence technique, experiments were conducted with a flow system at a total pressure of 740±10 Torr using He as diluent and carrier gas. The Temperature dependence of the rate coefficients was best described by the modified Arrhenius expressions k 1 (293-882 K)=(3.36±0.52)×10 -12 (T/300) 1.21 exp[(-1553±92)/T] cm 3 molecule -1 s -1 and k 2 (295-701 K)=(2.72±0.42)×10 -12 (T/300) 0.22 exp[(-915±62)/T] cm 3 molec -1 s -1
Stanislaw Gierlotka - One of the best experts on this subject based on the ideXlab platform.
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electrical properties vs microstructure of nanocrystallized v2o5 p2o5 glasses an Extended Temperature Range study
Solid State Ionics, 2011Co-Authors: Tomasz K. Pietrzak, Jerzy E. Garbarczyk, Marek Wasiucionek, Irena Gorzkowska, Jan L. Nowiński, Stanislaw GierlotkaAbstract:Abstract An electronically conducting nanomaterial was synthesized by nanocrystallization of a 90V 2 O 5 ·10P 2 O 5 glass and its electrical properties were studied in an Extended Temperature Range from − 170 to + 400 °C. The conductivity of the prepared nanomaterial reaches 2 ∙ 10 − 1 S cm − 1 at 400 °C and 2 ∙ 10 − 3 S cm − 1 at room Temperature. It is higher than that of the original glass by a factor of 25 at room Temperature and more than 100 below − 80 °C. A key role in the conductivity enhancement was ascribed to the material's microstructure, and in particular to the presence of the large number of small (ca. 20 nm) grains of crystalline V 2 O 5 . The observed conductivity dependencies are discussed in terms of the Mott's theory of the electronic hopping transport in disordered systems. Since V 2 O 5 is known for its ability to intercalate lithium, the presented results might be helpful in the development of cathode materials for Li-ion batteries.
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Electrical properties vs. microstructure of nanocrystallized V2O5–P2O5 glasses — An Extended Temperature Range study
Solid State Ionics, 2011Co-Authors: Tomasz K. Pietrzak, Jerzy E. Garbarczyk, Marek Wasiucionek, Irena Gorzkowska, Jan L. Nowiński, Stanislaw GierlotkaAbstract:Abstract An electronically conducting nanomaterial was synthesized by nanocrystallization of a 90V 2 O 5 ·10P 2 O 5 glass and its electrical properties were studied in an Extended Temperature Range from − 170 to + 400 °C. The conductivity of the prepared nanomaterial reaches 2 ∙ 10 − 1 S cm − 1 at 400 °C and 2 ∙ 10 − 3 S cm − 1 at room Temperature. It is higher than that of the original glass by a factor of 25 at room Temperature and more than 100 below − 80 °C. A key role in the conductivity enhancement was ascribed to the material's microstructure, and in particular to the presence of the large number of small (ca. 20 nm) grains of crystalline V 2 O 5 . The observed conductivity dependencies are discussed in terms of the Mott's theory of the electronic hopping transport in disordered systems. Since V 2 O 5 is known for its ability to intercalate lithium, the presented results might be helpful in the development of cathode materials for Li-ion batteries.
