A comparative kinetic study of xenon adsorption on a flat Pt(111) and stepped Pt(557) and Pt(112) surfaces

Journal Article · Fri Jun 15 00:00:00 EDT 1990 · Journal of Chemical Physics; (USA)

DOI:https://doi.org/10.1063/1.458155· OSTI ID:6971899

Siddiqui, H R; Chen, P J; Guo, X; Yates, Jr, J T ^[1]

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1. Surface Science Center, Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260 (US)

The adsorption and desorption kinetics for Xe on three Pt single crystalline surfaces have been measured using threshold temperature programmed desorption measurements. It has been found that the first-order desorption kinetic parameters at zero coverage for Xe on Pt(111) ({ital E}{sup 0}{sub {ital d}} =5.73{plus minus}0.50 kcal/mol; {nu}{sup 0}{sub {ital d}}=10{sup 12.5{plus minus}0.9} s{sup {minus}1}) are in excellent agreement with measurements made by a modulated molecular beam method ({ital E}{sup 0}{sub {ital d}} =5.65{plus minus}0.35 kcal/mol; {nu}{sup 0}{sub {ital d}}=10{sup 12.1} s{sup {minus}1}). The presence of step defect sites of varying density on Pt(557) (1/6 defects) and on Pt(112) (1/3 defects) is shown to have a marked influence on Xe desorption kinetics, producing larger values of {ital E}{sup 0}{sub {ital d}}{congruent}8.5--8.7 kcal/mol and larger values of {nu}{sup 0}{sub {ital d}} {congruent}10{sup 14} s{sup {minus}1} compared to Pt(111). In addition, for Pt(111), slight attractive Xe--Xe interactions are observed, whereas for Xe adsorption on step sites, repulsive Xe--Xe interactions are observed as the steps fill. Xe adsorption kinetics on Pt(111) at 87 K are consistent with an island growth mechanism. In contrast, on Pt(557) and Pt(112), the adsorption process does not seem to produce island growth on the terraces. These results, taken together, show that using Xe, defect sites on metals may be probed effectively with adsorption and desorption kinetic methods.

• OSTI ID: 6971899
• Journal Information: Journal of Chemical Physics; (USA), Vol. 92:12; ISSN 0021-9606
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
PLATINUM
SORPTIVE PROPERTIES
XENON
ADSORPTION
DEFECTS
DESORPTION
KINETICS
LOW TEMPERATURE
MORPHOLOGY
ELEMENTS
FLUIDS
GASES
METALS
NONMETALS
PLATINUM METALS
RARE GASES
SORPTION
SURFACE PROPERTIES
TRANSITION ELEMENTS
400201* - Chemical & Physicochemical Properties