Sie befinden Sich nicht im Netzwerk der Universität Paderborn. Der Zugriff auf elektronische Ressourcen ist gegebenenfalls nur via VPN oder Shibboleth (DFN-AAI) möglich.
mehr Informationen...
Steric Effects in the Chemisorption of Vibrationally Excited Methane on Ni(100)
Ist Teil von
Science (American Association for the Advancement of Science), 2010-07, Vol.329 (5991), p.553-556
Ort / Verlag
Washington, DC: American Association for the Advancement of Science
Erscheinungsjahr
2010
Link zum Volltext
Quelle
American Association for the Advancement of Science
Beschreibungen/Notizen
Newly available, powerful infrared laser sources enable the preparation of intense molecular beams of quantum-state prepared and aligned molecules for gas/surface reaction dynamics experiments. We present a stereodynamics study of the chemisorption of vibrationally excited methane on the (100) surface of nickel. Using linearly polarized infrared excitation of the C-H stretch modes of two methane isotopologues [CH₄(ν₃) and CD₃H(ν₁)], we aligned methane's angular momentum and vibrational transition dipole moment in the laboratory frame. An increase in methane reactivity of as much as 60% is observed when the laser polarization is parallel rather than normal to the surface. The dependence of the alignment effect on the rotational branch used for excitation indicates that alignment of the vibrational transition dipole moment of methane is responsible for the steric effect. Potential explanations for the steric effect in terms of an alignment-dependent reaction barrier height or electronically nonadiabatic effects are discussed.