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Author McMaster, M. C. ♦ Madix, R.J.
Source United States Department of Energy Office of Scientific and Technical Information
Content type Text
Language English
Subject Keyword INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY ♦ ETHANE ♦ ADSORPTION ♦ DISSOCIATION ♦ METHANE ♦ PLATINUM ♦ CHEMICAL REACTIONS ♦ ADHESION ♦ ALKANES ♦ CHEMICAL BONDS ♦ ENERGY DEPENDENCE ♦ MOLECULAR BEAMS ♦ MOLECULE COLLISIONS ♦ PROBABILITY ♦ SUPERSONIC FLOW ♦ TEMPERATURE DEPENDENCE ♦ VIBRATIONAL STATES ♦ BEAMS ♦ COLLISIONS ♦ ELEMENTS ♦ ENERGY LEVELS ♦ EXCITED STATES ♦ FLUID FLOW ♦ HYDROCARBONS ♦ METALS ♦ ORGANIC COMPOUNDS ♦ PLATINUM METALS ♦ SORPTION ♦ TRANSITION ELEMENTS 400201* -- Chemical & Physicochemical Properties
Abstract Supersonic molecular beam techniques were used to study the reactive adsorption dynamics of methane and ethane on Pt(110)--(1[times]2). The initial dissociative sticking probability, [ital S][sub 0], was measured as a function of surface temperature, incident translational energy, incident total vibrational energy, and incident polar angle at two azimuthal orientations. Under all experimental conditions, both alkanes dissociated via direct collisional activation. Over the range of translational energies studied here neither [ital S][sub 0](CH[sub 4]) nor [ital S][sub 0](C[sub 2]H[sub 6]) exhibited a dependence on nozzle temperature in these experiments suggesting that excitation of the normal vibrational motions of methyl deformation, methyl rocking, C--C stretching, and torsional vibrational modes do not play a significant role in the direct dissociation of either alkane on Pt(110)--(1[times]2) under these experimental conditions. The C--H stretching modes were not sufficiently populated to determine the extent of their participation. Methane and ethane displayed almost identical initial reaction probabilities at a fixed incident translational energy and polar angle, similar to our findings for methane and ethane dissociation on Pt(111). However, the reactivity of both species was about a factor of 2 [ital lower] on Pt(110)--(1[times]2) than observed on Pt(111) at a fixed incident translational energy and polar angle. When the crystal was positioned such that the tangential velocity component of the beam was incident along the atomic rows (the [1[bar 1]0] direction) the dissociation of both alkanes exhibited normal energy scaling.
ISSN 00219606
Educational Use Research
Learning Resource Type Article
Publisher Date 1993-06-15
Publisher Place United States
Journal Journal of Chemical Physics
Volume Number 98
Issue Number 12


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