27680-53-1Relevant articles and documents
State selected ion-molecule reactions by a TESICO technique. X. O+(ν) + CH4
Tanaka, Kenichiro,Kato, Tatsuhisa,Koyano, Inosuke
, p. 750 - 755 (1986)
Vibrational state selected (relative) reaction cross sections have been determined for ν=4-3 of the O2+ ion, for each of the three product channels of the reaction O2+(ν) + CH4, viz.O2+ (ν) + CH4 -> CH3O2+ + H ( 1 ) -> CH3+ + HO2 ( 2 ) -> CH4+ + O2, ( 3 ) using the TESICO (threshold electron-secondary ion coincidence) technique.At a fixed collision energy of 0.27 eV, it has been found that the cross section of exoergic channel ( 1 ) increases most prominently with increasing vibrational quantum number ν in the range ν = 0-2, but decreases sharply in going from ν = 2 to ν = 3.The cross sections of endoergic channels ( 2 ) and ( 3 ) also increase with increasing ν but their rates of increase are much smaller than that of channel ( 1 ) in the range ν = 0-2.When ν is increased to 3, however, charge transfer channel ( 3 ) is enhanced dramatically and the CH4+ ion becomes the most abundant product ion.The cross section of channel ( 2 ) also increases more sharply in going from ν = 2 to ν = 3 than in the range ν = 0-2, but the CH3+ ion still remains the least abundant of the three product ions.As a result of these variations in the individual cross sections, the overall cross section for the O2+ + CH4 reaction increases monotonically with increasing ν throughout the range studied (ν = 4-3) .The results are compared with that of the collision energy dependence as obtained in drift and flow- drift experiments and the implications are discussed in conjunction with the structure of the CH3O2+ ion and the relevant potential energy surfaces.
A crossed-beam scattering study of CH4+ and CH3+ formation in charge transfer collisions of Kr+ with CH4 at about 1 eV
Herman, Zdenek,Friedrich, Bretislav
, p. 7017 - 7023 (2007/10/02)
The dynamics of CH4+ and CH3+ ion formation in collisions of Kr+(2P3/2'1/2) with thermal CH4 has been investigated in a crossed beam experiment at a hyperthermal collision energy of 1.18 eV.The scattering data show that the CH4+ product is formed in a near-resonant exoergic process in which the most probable energy transferred to the target is practically equal to the recombination energy of the Kr+ projectile (resonant energy transfer); in addition a wide band of internal states of CH4+ up to +/-0.6 eV is populated in inelastic and superelastic collisions.In contrast, the CH3+ product is formed in dissociative charge transfer, with about one-half of the yield due to nonresonant, endoergic collisions of Kr+ (2P3/2).The other half of the CH3+ product is found to originate in near-resonant exoergic collisions of Kr+ (2P1/2).An estimate is given of the distribution of the total energy deposited in methane by the above processes.
Competitive reaction and quenching of vibrationally excited O2+ ions with SO2, CH4, and H2O
Durup-Ferguson, M.,Boehringer, H.,Fahey, D. W.,Fehsenfeld, F. C.,Ferguson, E. E.
, p. 2657 - 2666 (2007/10/02)
Vibrationally excited O2+ ions injected into a He buffered flow tube react rapidly with SO2 and H2O by charge transfer and with CH4 to produce CH3O2+, CH3+, and CH4+.It is found that the rapidly reacting states at thermal energy are O2+ (ν2) for SO2 and CH4 and O2+(ν3) for H2O, while the lower vibrationally excited states are rapidly quenched.When the reactions of SO2 and CH4 are studied in Ar buffer as a function of kinetic energy it is found that the vibrational temperature of Oz established through collisional excitation by the Ar buffer is perturbed by quenching collisions with the reactant molecules.This leads to observed reaction rate constants that change with reactant gas concentration.For the reaction of O2+ with CH4 the influence of kinetic and vibrational energy on the branching ratio of the reaction channels has been investigated.The present vibrational relaxation data for O2+(ν) by CH4, in conjunction with other recent measurements, allows a rather detailed picture of the mechanism to be drawn for this complicated reaction that involves the making and breaking of four chemical bonds.
