2 research outputs found
Energy distribution analysis of the wavepacket simulations of CH4 and CD4 scattering
The isotope effect in the scattering of methane is studied by wavepacket
simulations of oriented CH4 and CD4 molecules from a flat surface including all
nine internal vibrations. At a translational energy up to 96 kJ/mol we find
that the scattering is still predominantly elastic, but less so for CD4. Energy
distribution analysis of the kinetic energy per mode and the potential energy
surface terms, when the molecule hits the surface, are used in combination with
vibrational excitations and the corresponding deformation. They indicate that
the orientation with three bonds pointing towards the surface is mostly
responsible for the isotope effect in the methane dissociation.Comment: 20 pages LaTeX, 1 figure (eps), to be published in Surf. Sc
Bond breaking in vibrationally excited methane on transition metal catalysts
The role of vibrational excitation of a single mode in the scattering of
methane is studied by wave packet simulations of oriented CH4 and CD4 molecules
from a flat surface. All nine internal vibrations are included. In the
translational energy range from 32 up to 128 kJ/mol we find that initial
vibrational excitations enhance the transfer of translational energy towards
vibrational energy and increase the accessibility of the entrance channel for
dissociation. Our simulations predict that initial vibrational excitations of
the asymmetrical stretch (nu_3) and especially the symmetrical stretch (nu_1)
modes will give the highest enhancement of the dissociation probability of
methane.Comment: 4 pages REVTeX, 2 figures (eps), to be published in Phys. Rev. B.
(See also arXiv:physics.chem-ph/0003031). Journal version at
http://publish.aps.org/abstract/PRB/v61/p1565