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  • 1
    Electronic Resource
    Electronic Resource
    Reaction cross section and product ion time-of-flight measurements for collisions of N+ and N+2 with CO2 at suprathermal energies (1990)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 93 (1990), S. 7780-7786 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Charge exchange and dissociative ionization cross sections are reported for N+–CO2 and N+2–CO2 collisions at center-of-mass energies between 2 and 40 eV. Product ion kinetic energies are measured using time-of-flight techniques. Energy resonance considerations based on CO2 ionization Franck–Condon factors predict charge exchange to be slow for both of these reaction pairs. The N+–CO2 charge exchange, however, exhibits a large cross section and proceeds about one order of magnitude faster than the N+2–CO2 charge exchange. The formation of CO+ in N+–CO2 collisions is reported, while no dissociative ionization products are observed in the N+2–CO2 system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.459358
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  • 2
    Electronic Resource
    Electronic Resource
    Cross section and product time-of-flight measurements of the reaction of N+2 with H2O and D2O at suprathermal energies (1990)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 92 (1990), S. 1117-1125 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Charge exchange and hydrogen atom pickup cross sections, and product ion time-of-flight measurements are reported for N+2 –H2O(D2O) collisions at center-of-mass collision energies ranging between 1 and 15 eV. No isotope effect is detected for the charge exchange branch, while a significant isotope effect is observed for the atom pickup reaction. Throughout the measured energy range, the time-of-flight measurements show that the H2O+(D2O+) charge exchange product is produced with near-thermal energy in the laboratory frame, implying little or no momentum transfer. The charge exchange reaction products are therefore formed with internal energy comparable to the exothermicity of the reaction (2.96 eV). The atom pickup ion product velocity distributions and the atom pickup isotope effect are consistent with a spectator stripping mechanism.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.458173
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  • 3
    Electronic Resource
    Electronic Resource
    Cross sections and product kinetic energy analysis of H2O+–H2O collisions at suprathermal energies (1990)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 93 (1990), S. 3196-3206 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The reaction of H2O+ with H2O is studied using a longitudinal geometry double mass spectrometer in the collision energy range Ec.m.=0.5–25 eV. Cross sections are reported for oxonium ion (H3O+) production and the symmetric charge exchange. Isotopic substitution is used to discern the product branches, including the separation of the two channels for oxonium ion production: (i) proton transfer to the target molecule; and (ii) atom pickup by the primary ion. The largest branching ratio is observed for the charge exchange channel, where no isotope effect is detected in the investigated energy range. Proton transfer exhibits the second largest branching ratio and accounts for more than 90% of the oxonium ion production throughout the measured energy range. The proton transfer cross section is dependent on isotopic substitution, while the atom pickup channel is too weak to make a distinct statement on its isotopic behavior. Product ion energies, determined by time-of-flight measurements, are also reported for each of the three channels. These measurements show that most (〉95%) of the oxonium ions are formed via a direct, spectator stripping type mechanism while a small amount of reaction products exhibit considerable internal excitation. The charge exchange secondary ions are primarily formed at near-thermal energies in the laboratory frame. Small amounts of high laboratory energy product ions are also observed which at least partly originate through the dissociation of excited oxonium ions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.458852
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  • 4
    Electronic Resource
    Electronic Resource
    Chemiluminescence measurements of the N+2, N++H2O charge transfer systems at suprathermal energies: Direct probe of the dynamics of large cross section charge transfer processes (1990)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 93 (1990), S. 9189-9191 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The chemiluminescence from suprathermal N+2–H2O and N+–H2O collisions is studied using a new experiment. Intense H2O+A˜ 2A1–X˜ 2B1 emission is observed from the N+2 +H2O charge transfer whereas no emissions are detected from the N+–H2O system. OH A 2Σ+–X 2Π emission originating from the N+2+H2O atom pickup channel is also observed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.459208
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  • 5
    Electronic Resource
    Electronic Resource
    Dynamics of hyperthermal Kr++H2O charge-transfer collisions (1995)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 102 (1995), S. 6110-6120 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Cross section, time-of-flight (TOF) and luminescence measurements are reported for the Kr++H2O charge-transfer system. Cross section and TOF measurements were carried out in an octopole guided-ion beam apparatus and are reported for collision energies between 0.10–10 eV (c.m.). The charge-transfer cross section has approximately an E−0.5 dependence at low collision energies. TOF measurements of H2O+ products are characteristic of a near-resonant direct charge-transfer mechanism proceeding at long range. A smaller contribution of forward-scattered ions is attributed to the formation of longer-lived collision complexes. The TOF analysis based on the osculating complex model reveals significant energy transfer for orbiting trajectories. Low resolution product ion luminescence spectra (4 nm FWHM), taken at collision energies between 0.1–15 eV (c.m.), are consistent with the TOF measurements. The optical spectra show that H2O+ product ions are formed in A˜-state vibrational levels that are at or below the energy level of Kr+(2P1/2) reactants. No evidence is found for luminescence stemming from Kr+(2P3/2) reactants. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.469345
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  • 6
    Electronic Resource
    Electronic Resource
    Guided-ion beam measurements of X++NO (X=Ar, N2) reactions (1994)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 100 (1994), S. 7348-7359 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Cross section and product ion time-of-flight measurements are presented for the X++NO (X=Ar, N2) collision systems over a collision energy range of 0.1–20 eV (c.m.). The experiments are carried out in an octopole guided-ion beam apparatus. Charge transfer is the main channel observed and dissociative charge-transfer products are observed for collision energies equal to or greater than their respective thermodynamic thresholds. A weak channel leading to ArN+ and/or ArO+ is observed in the X=Ar system. The charge-transfer cross sections of the two collision systems are similar in magnitude and have approximately an E−1/2 dependence at near-thermal collision energies. The near-thermal cross sections are significantly less than the Langevin–Gioumousis–Stevens predictions for a reaction mediated by ion–induced dipole interactions and complex formation. The time-of-flight distributions of the Ar+, N+2+NO charge-transfer products are characteristic of near-resonant charge-transfer processes. At all collision energies studied, the charge-transfer reaction is dominated by a direct mechanism, but below 1 eV, the formation of a long-lived intermediate complex is also significant. The results are discussed in relation to statistical models and to constraints imposed by requirements of energy resonance and Franck–Condon overlap in charge-transfer reaction dynamics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.466879
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  • 7
    Electronic Resource
    Electronic Resource
    Guided-ion beam measurements of the O+(4S)+Xe charge-transfer reaction (1995)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 103 (1995), S. 144-149 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Guided-ion beam integral cross section measurements, product ion time-of-flight (TOF) measurements, and doubly differential cross sections are presented for the O+(4S)+Xe→O+Xe+ charge-transfer reaction. The integral cross section is observed to increase monotonically with mean center-of-mass collision energy (ET) from 0.72 A(ring)2 at 0.1 eV to 26.9 A(ring)2 at 35.2 eV. Product ion TOF measurements show that the primary contribution to the charge-transfer cross section arises from a direct electron transfer at long range of the Demkov type. The collision energy dependence of the cross section for center-of-mass (c.m.) forward-scattered Xe+ ions reveals that this minor contribution to the total cross section arises from a hard-sphere-type scattering that primarily involves a Landau–Zener-type diabatic curve crossing at shorter range. Doubly differential cross sections at 4.4 eV indicate that translational to product internal energy transfer is inefficient even at small impact parameters and that the spin-allowed Xe+(2P)+O(3P) product channels are preferentially populated. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.469652
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  • 8
    Electronic Resource
    Electronic Resource
    Guided-ion beam measurements of N++H2O charge-transfer and chemical reaction channels (1994)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 100 (1994), S. 5656-5665 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Guided-ion beam measurements of N++H2O charge-transfer and chemically reactive channels are presented for collision energies ranging from 0.1 eV to 20 eV c.m. The charge-transfer reaction is not as efficient as expected considering the favorable Franck–Condon overlap at resonance. The analysis of product-ion time-of-flight spectra demonstrates that energy transfer is efficient in orbiting collisions at all investigated collision energies. At low collision energies, formation of NO+, and HNO+ and/or NOH+, is observed. The chemically reactive channels exhibit a near 1/ET dependence at low collision energies. Above 0.5 eV, the HNO+/NOH+ cross section drops abruptly below the instrumental sensitivity. The NO+ cross section exhibits a minimum at 1.2 eV, followed by an increase in cross section with energy reaching a maximum of 4×10−16 cm2 at 7 eV before decreasing again. The decline at higher energies is partly attributed to a dissociative loss of the product ions. O+ formation is observed at and above the thermodynamic threshold associated with the O++N+2H asymptotic limit.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.467275
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  • 9
    Electronic Resource
    Electronic Resource
    The reaction of O+(4S) and N2(X 1Σg+) revisited: Recoil velocity analysis of the NO+ product (1999)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 111 (1999), S. 3954-3960 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The guided-ion beam method has been used to measure time-of-flight (TOF) spectra of the NO+ produced in the reaction of O+(4S) and N2(X 1Σg+). Particular care was taken to minimize the participation of the O+(2D,2P) metastables in the reactions, the success of which is validated by measuring the absolute cross section for the reaction as a function of collision energy in the near-thermal to 1.5 eV range. In this range, the cross section exhibits a region of low reactivity at near-thermal energies, which can be obscured by reactions of metastables and other effects, and a region of sharply increasing reactivity above a threshold of collision energy (approximate)0.3 eV. The velocity-transformed TOF spectra, at collision energies of 0.51 eV, 0.80 eV, 3.2 eV, and 6.3 eV, indicate two reaction mechanisms: in the first, product ions are scattered backward with inefficient translational to internal energy conversion; in the second, product ions arise from intermediate collision complexes with efficient translational energy conversion. The first mechanism is associated with the passage through the spin-forbidden doublet ground state N2O+ intermediate, while the second involves passage through an endothermic quartet intermediate. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.479697
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  • 10
    Electronic Resource
    Electronic Resource
    THE SHUTTLE GLOW PHENOMENON (1998)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Physical Chemistry 49 (1998), S. 73-98 
    Details
    ISSN: 0066-426X
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Chemistry and Pharmacology , Physics
    Notes: Abstract Spacecraft in low earth orbit exhibit an unusual phenomenon: Surfaces facing the atmospheric wind produce a bright orange glow. This phenomenon was first noticed on the space shuttle but has since been verified as occurring on all spacecraft. The intensity of the glow depends on atmospheric density, on the angle between the velocity vector and the spacecraft surface, and on the temperature of the surface. This review summarizes the observations as well as the current explanation for the glow, namely its being due to NO*2 formed in surface-aided recombination between O and NO. Laboratory measurements and surface studies related to the phenomenon are briefly discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1146/annurev.physchem.49.1.73
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