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  • 1
    Electronic Resource
    Electronic Resource
    Gas-phase negative-ion chemistry of diazomethane (1989)
    s.l. : American Chemical Society
    The @journal of organic chemistry 54 (1989), S. 1846-1850 
    Details
    ISSN: 1520-6904
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/jo00269a020
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  • 2
    Electronic Resource
    Electronic Resource
    Gas-phase isotope-exchange reactions with chloride ion (1989)
    s.l. : American Chemical Society
    The @journal of physical chemistry 〈Washington, DC〉 93 (1989), S. 1130-1134 
    Details
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/j100340a021
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  • 3
    Electronic Resource
    Electronic Resource
    Chemistry of CFn+ (n = 1-3) ions with halocarbons (1992)
    s.l. : American Chemical Society
    The @journal of physical chemistry 〈Washington, DC〉 96 (1992), S. 2597-2603 
    Details
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/j100185a038
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  • 4
    Electronic Resource
    Electronic Resource
    Rotational temperature dependence of the branching ratio for the reaction of O+ with HD (1991)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 95 (1991), S. 8120-8123 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Rate constants and branching fractions for the reaction of O+ with HD have been measured as a function of average center-of-mass kinetic energy (〈KEcm〉) at three temperatures: 93, 300, and 509 K. Both OH+ and OD+ were produced. The rate constants were found to equal 1.2×10−9 cm3 s−1, independent of temperature or 〈KEcm〉. The branching into OH+ was observed to increase with 〈KEcm〉. Differences in the branching fractions were seen at a particular 〈KEcm〉 at different temperatures. These differences are attributed to a rotational temperature dependence such that increasing rotational temperature decreases the fraction of OH+ produced. The data are in agreement with a theoretical calculation and previous measurements.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.461291
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  • 5
    Electronic Resource
    Electronic Resource
    Reactions of Ar+ with halocarbons and of I+ with CF3I (1992)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 97 (1992), S. 173-179 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The gas phase reactions of Ar+ with the halocarbons CF3Cl, CF3Br, CF3I, CF4, C2F6, and C2F4 have been studied using a variable temperature-selected ion flow tube (VT-SIFT) instrument operated at 298 and 500 K. Rate constants and product branching percentages were measured at both temperatures. Ar+ reacts at the collisional rate with all of the above neutrals at both 298 and 500 K. The reactions with CF3X yield CF+3 and CF2X+ for all X (the reaction with CF4 produces only CF+3 ). For X=I, there is an additional channel leading to the ionic product I+. The reaction of Ar+ with C2F6 produces both CF+3 and C2F+5. The reaction of Ar+ with C2F4 forms a rich product spectrum consisting of the ions CF+, CF+2, CF+3, C2F+3, and C2F+4. The reaction product distributions are compared with results from ionization experiments such as photoion–photoelectron coincidence (PIPECO) and electron impact mass spectrometry, and in some cases excellent agreement is found. The reaction of I+ with CF3I, which is a secondary reaction in the Ar+/CF3I system, was investigated at 298 K in separate experiments. This reaction is rapid and forms four product ions: CF+3, CF2I+, CF3I+, and I+2. The results are compared with previously published information.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.463605
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  • 6
    Electronic Resource
    Electronic Resource
    Temperature, kinetic energy, and internal energy dependences of the rate constant and branching fraction for the reaction of O+ (4S) with CO2 (1992)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 96 (1992), S. 270-274 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Rate constants and branching fractions were measured for the reaction of O+ (4S) with CO2 as a function of average ion-neutral center-of-mass kinetic energy (〈KEcm〉) at several temperatures. The reaction produces both O+2 and CO+2 as product ions. The total rate constants were found to be nearly collisional at low 〈KEcm〉 and to decrease slightly at higher 〈KEcm〉. No temperature dependence of the rate constants was found at any given 〈KEcm〉, indicating that neither CO2 rotational excitation nor CO2 bending mode excitation has much effect on the overall reactivity. In contrast, the branching fraction for the endothermic charge transfer channel leading to CO+2 was found to increase with increasing 〈KEcm〉 and also to increase with temperature at fixed 〈KEcm〉. Analysis of the data indicates that the branching fraction depends on the total energy in the system (electronic, kinetic, rotational, and vibrational).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.462514
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  • 7
    Electronic Resource
    Electronic Resource
    The effect of low frequency vibrations in CH4 on the rate constant for the reaction of O+2 (X 2Πg, v=0) with CH4 (1992)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 96 (1992), S. 275-284 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The rate constant for the reaction of O+2 with CH4 has been measured as a function of average center-of-mass kinetic energy, 〈KEcm〉, at several temperatures over the range 93–545 K. The rate constant decreases with increasing 〈KEcm〉 at low 〈KEcm〉 and increases at higher 〈KEcm〉; the position of the resulting minimum depends on temperature. We have observed small differences in the rate constants measured at the same total 〈KEcm〉 but at different temperatures in the low temperature regime (T≤300 K). These differences, i.e., decreasing rate constants with increasing temperature, are discussed in terms of the possibility of a rate constant which is dependent upon rotational energy. At higher temperatures, 430 and 545 K, we find that the rate constant is significantly larger than that measured at lower temperatures at a given 〈KEcm〉. This enhanced reactivity is attributed to vibrational excitation in the CH4. From these data, we derive a rate constant for vibrationally excited CH4 (in the low frequency modes) that is approximately a factor of 20 greater than the rate constant for the ground vibrational state. The data disagree with an early study of this type at low temperature. The disagreement is discussed, and arguments are presented which indicate that the earlier data are in error at low temperature with an applied drift field. The use of these data for deriving effective reaction temperatures in other nonthermal experiments is also discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.462515
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  • 8
    Electronic Resource
    Electronic Resource
    Evidence for an influence of rotational energy on the rate constants for the reaction of Ar+(2P3/2) with N2 (1990)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 93 (1990), S. 4761-4765 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Rate constants for the charge transfer reaction of Ar+(2P3/2) with N2 were measured as a function of average center-of-mass kinetic energy (〈KEcm〉) at three temperatures. The rate constants increase rapidly with (〈KEcm〉) at all temperatures. The thermal activation energy is derived to be 0.07 eV, which is approximately the value of the endothermicity of the reaction when N+2 (v=1) is produced. The rate constants vary with temperature at a particular 〈KEcm〉, indicating either an effect due to differing energy distributions in the drift tube at different temperatures or that the reactivity depends on the rotational temperature of N2. Comparing the data at constant average total energy indicates that translational and rotational energy have a similar effect on the reactivity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.458666
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  • 9
    Electronic Resource
    Electronic Resource
    Negative ion chemistry of SF4 (1995)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 102 (1995), S. 8865-8873 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: A selected ion flow tube was used to conduct an extensive study of negative ion–molecule reactions of SF4 and SF−4. Rate constants and product ion branching fractions were measured for 56 reactions. The reactions bracket both the electron affinity of SF4 (1.5±0.2 eV or 34.6±4.6 kcal mol−1) and the fluoride affinity of SF3 (1.84±0.16 eV or 42.4±3.2 kcal mol−1). These results may be combined to give the neutral bond energy D(SF3–F)=3.74±0.34 eV or 86.2±7.8 kcal mol−1, independent of other thermochemical data except for the accurately known electron affinity of F. The heat of formation of SF−4 is derived from the electron affinity of SF4: ΔfH(SF−4)=−9.2±0.3 eV or −212.9±7.5 kcal mol−1. Lower limits to EA(SF2) and EA(SF3) are deduced from observation of SF−2(35%) and SF−3(65%) ion products of the reaction S−+SF4. Rapid fluoride transfer from both SF−2 and SF−3 to SF4 places upper limits on the electron affinities of SF2 and SF3. The combined results are 0.2 eV≤EA(SF2)≤1.6 eV and 2.0 eV≤EA(SF3)≤3.0 eV. We review the status of measurements of EA(SFn), n=1–7. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.468940
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  • 10
    Electronic Resource
    Electronic Resource
    The formation and destruction of H3O− (1994)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 100 (1994), S. 5706-5714 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We report the first measurements of rate constants for formation and reaction of the hydrated-hydride ion H3O−. We studied the Kleingeld–Nibbering reaction [Int. J. Mass Spectrom. Ion Phys. 49, 311 (1983)], namely, dehydrogenation of formaldehyde by hydroxide to form hydrated-hydride ion and carbon monoxide. The OD−+H2CO reaction is about 35% efficient at 298 K, with OD−/OH− exchange occurring in about half the reactions. H3O− was observed to undergo thermal dissociation in a helium carrier gas at room temperature with a rate constant of 1.6×10−12 cm3 s−1. We also studied a new reaction in which H3O− is formed: The association of OH− with H2 in a He carrier gas at low temperatures. The rate coefficient for this ternary reaction is 1×10−30 cm6 s−1 at 88 K. Rate coefficients and product branching fractions were determined for H3O− reactions with 19 neutral species at low temperatures (88–194 K) in an H2 carrier. The results of ion-beam studies, negative-ion photoelectron spectroscopy, and ion-molecule reaction data allow us to specify the hydride–water bond energy D0298(H−−H2O)=14.4±1.0 kcal mol−1 (0.62±0.04 eV). The heat of formation of H3O−, −37.5±1.0 kcal mol−1, and the proton affinity of H3O−, 386.0±1.0 kcal mol−1, are derived from these results. Dissociation of H3O− into OH− and H2 requires 4.5±1.0 kcal mol−1 energy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.467136
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