Threshold Energy for Substitution of T for D in CD4

Chou, C. C.; Rowland, F. S.

doi:10.1063/1.1671443

Cited by 49 publications

(15 citation statements)

References 12 publications

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“…The threshold energy has been measured for one comparable case, tritium + CH4, and an estimate of 150 kJ mol-' was given. 14 No similar fall in IRP has been observed in isotopically mixed systems, but with mass-spectrometric detection of H D product it is not possible to distinguish between the two reaction modes.…”

Section: Reaction Probabilities For H + Cjhsmentioning

confidence: 95%

Reaction probabilities and cross-sections in the reaction of isotopically pure hydrogen atoms and propane

Nicholas¹,

Vaghjiani²

1987

J. Chem. Soc., Faraday Trans. 2

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Section: Reaction Probabilities For H + Cjhsmentioning

confidence: 95%

Reaction probabilities and cross-sections in the reaction of isotopically pure hydrogen atoms and propane

Nicholas¹,

Vaghjiani²

1987

J. Chem. Soc., Faraday Trans. 2

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“…The exchange reaction, however, will only be of importance at very high energies, the energy barrier to exchange being 35 kcal mol Ϫ1 , 19 whereas that to abstraction is approximately 10 kcal mol Ϫ1 . 12 Thus, at thermally accessible energies the abstraction reaction will dominate alleviating the need for a fivefold symmetric potential surface.…”

Section: Potential Energy Surfacementioning

confidence: 99%

Classical trajectory studies of the reaction CH4+H→CH3+H2

Jordan

Gilbert

1995

The Journal of Chemical Physics

157

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Articles you may be interested inMode specific dynamics of the H2 + CH3 → H + CH4 reaction studied using quasi-classical trajectory and eightdimensional quantum dynamics methods J. Chem. Phys. 143, 154307 (2015) Trajectory data are reported for the reaction CH 4 ϩH→CH 3 ϩH 2 , designed to provide information that can be used to test approximate quantitative theories for the dynamics of abstraction reactions. A potential function was devised which properly reflects the nuclear permutation symmetry of the process. Microscopic reaction rate coefficients were obtained as functions of fixed rotational and vibrational energy, and of the angular momentum. The data indicated significant uncoupling between the various modes although, at a minimum, the symmetric stretch is directly coupled to the reaction coordinate at the transition state. The data were used to test the assumption that the total angular momentum, J, may be approximated by the orbital angular momentum, L. L is approximately conserved from the reactant to the saddle point configuration in reactive and nonreactive collisions and may be well approximated by J. The angular momentum about the long axis of the reacting system ͑equivalent to the K quantum number͒ is not conserved in either reactive or nonreactive trajectories.

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“…Hot‐atom chemistry has established the existence of the abstraction and exchange channels by using T atoms from nuclear recoil experiments16 and photolytic sources 17…”

mentioning

confidence: 99%

Dynamics of the Simplest Reaction of a Carbon Atom in a Tetrahedral Environment

2003

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Reactions occurring at a carbon center are one of the most important and useful classes of reactions in chemistry. The simplest reaction at a carbon atom with a tetrahedral environment is that of an H atom with methane, and understanding this prototypical reaction has implications for a number of fields ranging from organic and combustion chemistry to fundamental reaction dynamics. Consequently, it has been the subject of numerous experimental studies [1] exploring the kinetics and isotope effects of both the forward and reverse reactions. Recent theoretical work includes new potential energy surface calculations, [2][3][4][5][6] direct dynamics studies, [7] calculation of isotope effects, [8] and new quantum scattering methods [9] that have been reviewed by Althorpe and Clary.[10]Herein we report the first study of the nascent CD 3 products from the H + CD 4 reaction. This isotope combination was chosen for experimental reasons because this arrangement allows for the detection of all possible reaction products: CD 3 , HD and D. We also examined the CH 3 products from the H + CH 4 reaction and find that it shows very similar behavior [11] to that reported herein for the H + CD 4 reaction. By using the well-established photoloc technique, [12] we find that at a collision energy of 1.95 AE 0.05 eV the CD 3 products are produced in their ground vibrational state or have one quantum of excitation in the low-frequency umbrella-bending mode (n 2 ). In addition, the CD 3 products are sideways/backward scattered [hcos qi = À0.20 AE 0.09] with respect to the incident H-atom direction. This result stands in stark contrast with the benchmark H + D 2 !HD + D bimolecular exchange reaction in which the D atom is scattered in the same direction as the incoming H atom, thus indicating a rebound mechanism.[13] The H + D 2 reaction is a logical choice for comparison with the H + CD 4 abstraction reaction because they are both nearly thermoneutral and have similar classical barriers. [14,15] We propose two possible explanations for the unusual angular distribution of the CD 3 products: (1) a stripping mechanism is more important at this energy than a rebound mechanism, and (2) a competition between abstraction and exchange diminishes the probability for abstraction at small impact parameters.Hot-atom chemistry has established the existence of the abstraction and exchange channels by using T atoms from nuclear recoil experiments [16] and photolytic sources.[17] Equation (1) and Equation (2) are close to thermoneutralbut have very different classical barrier heights (0.65 and 1.65 eV respectively). [14] Since the early hot-atom studies, experimental probes of the dynamics have been rather sparse. Valentini and coworkers [18] examined the abstraction channel by measuring the rovibrational state distributions of the HD product from H + CD 4 at 1.5 eV by using coherent antiStokes Raman spectroscopy (CARS). They found that the total cross section for reaction is 0.14 AE 0.03 2 , from which it is concluded that the maximum impact paramete...

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Threshold Energy for Substitution of T for D in CD4

Cited by 49 publications

References 12 publications

Reaction probabilities and cross-sections in the reaction of isotopically pure hydrogen atoms and propane

Reaction probabilities and cross-sections in the reaction of isotopically pure hydrogen atoms and propane

Classical trajectory studies of the reaction CH4+H→CH3+H2

Dynamics of the Simplest Reaction of a Carbon Atom in a Tetrahedral Environment

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