Dynamics of molecular adsorption of ethane with Pt(111): A supersonic molecular beam study

Journal Article · Thu Feb 07 04:00:00 EST 1991 · Journal of Physical Chemistry; (United States)

DOI:https://doi.org/10.1021/j100156a005· OSTI ID:5201926

Arumainayagam, C R; Schoofs, G R; McMaster, M C; Madix, R J ^[1]

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1. Stanford Univ., CA (USA)

The molecular interaction of ethane with Pt(111) was investigated by using supersonic molecular beam techiques and temperature-programmed desorption (TPD). Ethane adsorbs molecularly on the terrace sites of Pt(111) at 95 K with a saturation coverage of ca. 0.3 monolayer and desorbs at ca. 132 K during TPD. Isothermal desorption experiments suggest that ethane desorbs from the second layer with first-order desorption kinetics. Dissociation of molecularly adsorbed ethane is negligible upon subsequent heating. The trapping probability of ethane on the clean surface at normal incidence decreases from approximately 0.91 to 0.13 as the incident translational energy, E{sub T}, increases from 6 to 40 kJ/mol at a surface temeprature of 95 K in apparent semiquantitative agreement with a modified hard-cube model. However, over a range of incident angles, {theta}{sub i}, the initial trapping probability scales with E{sub T}cos{sup 0.6} {theta}{sub i} rather than with E{sub t} cos{sup 2}{theta}{sub i}, demonstrating the participation of momentum parallel to the surface in the trapping process and the necessity of more sophisticated theories, such as three-dimensional trajetory calculations, to adequately describe trapping over a wide range of incident translational energies and incident angles.

• DOE Contract Number: FG03-86ER13468
• OSTI ID: 5201926
• Journal Information: Journal of Physical Chemistry; (United States), Journal Name: Journal of Physical Chemistry; (United States) Vol. 95:3; ISSN 0022-3654; ISSN JPCHA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
ADSORPTION
ALKANES
BEAMS
CHEMICAL REACTION KINETICS
DATA
ELEMENTS
ETHANE
EXPERIMENTAL DATA
HYDROCARBONS
INFORMATION
KINETICS
LOW TEMPERATURE
MEASURING METHODS
METALS
MOLECULAR BEAMS
NUMERICAL DATA
ORGANIC COMPOUNDS
PLATINUM
PLATINUM METALS
REACTION KINETICS
SORPTION
SURFACE PROPERTIES
TRANSITION ELEMENTS