Product Translational Energy Distributions of Methyl Radical Reactions

1977 ◽  
Vol 81 (2) ◽  
pp. 142-144 ◽  
Author(s):  
L. C. Brown ◽  
J. C. Whitehead ◽  
R. Grice
Keyword(s):  
Radical Reactions ◽  
Translational Energy ◽  
Methyl Radical ◽  
Energy Distributions

Scattering of Low-Energy (5-12 eV) C2D4•+ Ions from Room-Temperature Carbon Surfaces

2008 ◽  
Vol 73 (6-7) ◽  
pp. 755-770 ◽  
Author(s):  
Andriy Pysanenko ◽  
Ján Žabka ◽  
Zdeněk Herman
Keyword(s):  
Survival Probability ◽  
Room Temperature ◽  
Incident Angle ◽  
Pyrolytic Graphite ◽  
Carbon Surface ◽  
Translational Energy ◽  
Energy Distributions ◽  
Surface Mass ◽  
Fragment Ions ◽  
Product Ions

The scattering of the hydrocarbon radical cation C2D4•+ from room-temperature carbon (highly oriented pyrolytic graphite, HOPG) surface was investigated at low incident energies of 6-12 eV. Mass spectra, angular and translational energy distributions of product ions were measured. From these data, information on processes at surfaces, absolute ion survival probability, and kinematics of the collision was obtained. The projectile ion showed both inelastic, dissociative and reactive scattering, namely the occurrence of H-atom transfer reaction with hydrocarbons present on the room-temperature carbon surface. The absolute survival probability of the ions for the incident angle of 30° (with respect to the surface) decreased from about 1.0% (16 eV) towards zero at incident energies below 10 eV. Estimation of the effective surface mass involved in the collision process led to m(S)eff of about 57 a.m.u. for inelastic non-dissociative collisions of C2D4•+ and of about 115 a.m.u. for fragment ions (C2D3+, C2D2•+) and ions formed in reactive surface collisions (C2D4H+, C2D2H+, contributions to C2D3+ and C2D2•+). This suggested a rather complex interaction between the projectile ion and the hydrocarbon-covered surface during the collision.

Charge Transfer Between CO22+ and Ar or Ne at Collision Energies 3-10 eV

2003 ◽  
Vol 68 (1) ◽  
pp. 178-188 ◽  
Author(s):  
Libor Mrázek ◽  
Ján Žabka ◽  
Zdeněk Dolejšek ◽  
Zdeněk Herman
Keyword(s):  
Charge Transfer ◽  
Excited States ◽  
Ground State ◽  
Scattering Method ◽  
Translational Energy ◽  
Centre Of Mass ◽  
Energy Distributions ◽  
Zener Model ◽  
Beam Scattering ◽  
Product Ions

The beam scattering method was used to investigate non-dissociative single-electron charge transfer between the molecular dication CO22+ and Ar or Ne at several collision energies between 3-10 eV (centre-of-mass, c.m.). Relative translational energy distributions of the product ions showed that in the reaction with Ar the CO2+ product was mainly formed in reactions of the ground state of the dication, CO22+(X3Σg-), leading to the excited states of the product CO2+(A2Πu) and CO2+(B2Σu+). In the reaction with Ne, the largest probability had the process from the reactant dication excited state CO22+(1Σg+) leading to the product ion ground state CO2+(X2Πg). Less probable were processes between the other excited states of the dication CO22+, (1∆g), (1Σu-), (3∆u), also leading to the product ion ground state CO2+(X2Πg). Using the Landau-Zener model of the reaction window, relative populations of the ground and excited states of the dication CO22+ in the reactant beam were roughly estimated as (X3Σg):(1∆g):(1Σg+):(1Σu-):(3∆u) = 1.0:0.6:0.5:0.25:0.25.

Individual rate constants of methyl radical reactions in the pyrolysis of dimethyl ether

1977 ◽  
Vol 55 (23) ◽  
pp. 4128-4134 ◽  
Author(s):  
Andrew M. Held ◽  
Kim C. Manthorne ◽  
Philip D. Pacey ◽  
Howard P. Reinholdt
Keyword(s):  
Dimethyl Ether ◽  
Rate Constants ◽  
Flow System ◽  
Average Concentration ◽  
Radical Reactions ◽  
Methyl Radical ◽  
Warm Up ◽  
Secondary Reactions ◽  
Ultraviolet Absorption Spectroscopy ◽  
Individual Rate

Dimethyl ether was pyrolyzed in a flow system at 10 to 80 Torr and 1005 K. The average concentration of CH3 radicals in the reactor was measured by ultraviolet absorption spectroscopy. Product yields were measured by gas chromatography. The system was simulated using a computer program, taking into account the warm-up of the entering gas and the occurrence of secondary reactions. Rate constants were varied to find values consistent with experimental observations. The limiting, high pressure rate constant for the recombination of CH3 was estimated to be 1010.5 ± 0.5ℓ mol−1 s−1. Estimated rate constants for the reactions[Formula: see text]were 107.12 ± 0.2ℓ mol−1 s−1 and 107.5 ± 0.4ℓ mol−1 s−1, respectively.

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