F+:Highly flammable;74-82-8Relevant articles and documents
Kinetics of the reaction of O2+ with CH4 from 500 to 1400 K: A case for state specific chemistry
Dotan,Viggiano
, p. 6112 - 6118 (2007/10/03)
The temperature dependent rate constants and branching ratios for the reaction of O2+ with CH4 and O2 with CD4 from 500 to 1400 K were determined. By comparing to previous studies, the influence on vibrational excitation in the CH4 reactant was derived.
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.
Dissociation dynamics of CH4+ core ion in the 2A1 state
Furuya, Kenji,Kimura, Katsumi,Sakai, Yasuhiro,Takayanagi, Toshinobu,Yonekura, Nobuaki
, p. 2720 - 2728 (2007/10/02)
Threshold-photoelectron photoion coincidence (TPEPICO) spectra of CH4 have been observed with synchrotron radiation at the excitation to the 2A1 (υ1=0-3) ionic states as well as to the 4pt2 Rydberg (υ1 = 0-4) states.In all the TPEPICO spectra observed, the CH3+ band shape was almost rectangular, which suggests that the translational and internal energy distributions of CH3+ are very narrow.The total kinetic energy releases (KERs) have been estimated from the CH3+ band shape.As a result, it was found that the CH3+ species were in an electronically excited state.There was a narrow distribution of the total KERs and similarity in the TPEPICO CH3+ band shapes between the spectra at the 2A1 ionic state and the 4pt2 Rydberg state excitations, which led to the conclusion that the Rydberg electron is just a spectator and the dissociation of the core ion plays an important role in dissociation through the 4pt2 Rydberg state.Similar results have also been obtained for CH2+ and CH+ productions.However, on the other hand, an H+ fragment has been observed only at the 2A1 state excitation.It showed a band with a long tail in the slower flight time region.The total average KERs and the decay rates have been estimated from band shape simulation.From these results, it has been found that a dissociation limit of the H+ ion exists just below the 2A1 ionic state.The dissociation mechanisms through the 4pt2 Rydberg state have been discussed in detail in comparison with those of the 2A1 ionic state.
State selected ion-molecule reactions by a TESICO technique. X. O+(ν) + CH4
Tanaka, Kenichiro,Kato, Tatsuhisa,Koyano, Inosuke
, p. 750 - 755 (2007/10/02)
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.
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.
Reactions of He+, Ne+, and Ar+ with CH4, C2H6, SiH4, and Si2H6
Chatham, H.,Hils, D.,Robertson, R.,Gallagher, A. C.
, p. 1301 - 1311 (2007/10/02)
The rate coefficients and product-ion distributions for the reactions of He+ and Ar+ with silane and disilane have been measured in a drift tube, typically for collision energies of 0.01-1 eV.The total charge-exchange rate coefficients are found to be roughly independent of E/N, or collision energy, and are about equal to the Langevin values for the reactions of He+ with SiH4 and C2H6 and Ar+ with CH4 and C2H6.The He+ rate coefficients on CH4 and Si2H6, and the Ne+ rate coefficients on SiH4 and Si2H6 are 50percent to 80percent of the Langevin values, while the Ar+ rate coefficients on SiH4 and Si2H6 are much smaller.Product ions tend to be hydrogen poor with very infrequent breaking of the C-C or Si-Si bonds.Furthermore, hydrogen stripping is more severe for the silanes than the alkanes.These product-ion distributions bear no resemblance to the product-ion distributions of either photoionization or electron collisional ionization.
