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Title: Modulated molecular beam scattering of CO and NO from Pt(111) and the stepped Pt(557) crystal surfaces

Abstract

The modulated molecular beam scattering of CO and NO from Pt(111) and Pt(557) have been studied in the temperature range of 350-1100 K. For CO scattered from Pt(111), an adsorption-desorption model with constant sticking coefficient fits the data well above 500°K, The best rate parameters are: {nu}=2.9x10{sup 13}, E=29.9 kcal/mole, and S=0.74. For CO scattered from Pt(557) the same model fits the data well above 550°K and the best rate parameters are {nu}=7.9x10{sup 13}, E=33.6 kcal/mole, and S=0.74. The higher activation energy for desorption from the stepped Pt(557), as compared to the flat Pt(111), suggests that while the incident molecules can be adsorbed at the step as well as at the terrace, their desorption energy is influenced by the presence of steps. An adsorption-desorption model with coverage-dependent sticking coefficient fits the data obtained at all temperatures well for both surfaces without change of the kinetic parameters. For NO scattered from Pt(111), the adsorption-desorption model with constant sticking coefficient fits the data well above 525°K using the rate parameters of {nu}=6.2x10{sup 13}, E=28.6 kcal/mole, and S=0.65. For NO scattered from Pt(557), the same model fits the data well above 525°K with {nu}=1.2x10{sup 14}, E=32.3 kcal/mole, and S=0.71. The higher activation energymore » suggests again that NO desorption is influenced by the presence of steps. Below 525°K, the NO scattering results are quite different from those of CO and can not be simulated with the simple models that were tried. The data can be used, however, to rule out several models of surface interactions. NO does not dissociate detectably between 400 K ~1200 K under our experimental conditions. The sticking coefficient decreases with increasing coverage.« less

Authors:
;
Publication Date:
Research Org.:
Ernest Orlando Lawrence Berkeley National Laboratory, Berkeley, CA (US). Materials Sciences Division
Sponsoring Org.:
USDOE
OSTI Identifier:
1108709
Report Number(s):
LBL-11787
Journal ID: ISSN 0039-6028
DOE Contract Number:  
DE-AC02-05CH11231
Resource Type:
Journal Article
Journal Name:
Surface Science
Additional Journal Information:
Journal Volume: 107; Journal Issue: 2-3; Related Information: pp. 573-585 in published journal article; Journal ID: ISSN 0039-6028
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY

Citation Formats

Lin, T. H., and Somorjai, G. A. Modulated molecular beam scattering of CO and NO from Pt(111) and the stepped Pt(557) crystal surfaces. United States: N. p., 1980. Web.
Lin, T. H., & Somorjai, G. A. Modulated molecular beam scattering of CO and NO from Pt(111) and the stepped Pt(557) crystal surfaces. United States.
Lin, T. H., and Somorjai, G. A. 1980. "Modulated molecular beam scattering of CO and NO from Pt(111) and the stepped Pt(557) crystal surfaces". United States. https://www.osti.gov/servlets/purl/1108709.
@article{osti_1108709,
title = {Modulated molecular beam scattering of CO and NO from Pt(111) and the stepped Pt(557) crystal surfaces},
author = {Lin, T. H. and Somorjai, G. A.},
abstractNote = {The modulated molecular beam scattering of CO and NO from Pt(111) and Pt(557) have been studied in the temperature range of 350-1100 K. For CO scattered from Pt(111), an adsorption-desorption model with constant sticking coefficient fits the data well above 500°K, The best rate parameters are: {nu}=2.9x10{sup 13}, E=29.9 kcal/mole, and S=0.74. For CO scattered from Pt(557) the same model fits the data well above 550°K and the best rate parameters are {nu}=7.9x10{sup 13}, E=33.6 kcal/mole, and S=0.74. The higher activation energy for desorption from the stepped Pt(557), as compared to the flat Pt(111), suggests that while the incident molecules can be adsorbed at the step as well as at the terrace, their desorption energy is influenced by the presence of steps. An adsorption-desorption model with coverage-dependent sticking coefficient fits the data obtained at all temperatures well for both surfaces without change of the kinetic parameters. For NO scattered from Pt(111), the adsorption-desorption model with constant sticking coefficient fits the data well above 525°K using the rate parameters of {nu}=6.2x10{sup 13}, E=28.6 kcal/mole, and S=0.65. For NO scattered from Pt(557), the same model fits the data well above 525°K with {nu}=1.2x10{sup 14}, E=32.3 kcal/mole, and S=0.71. The higher activation energy suggests again that NO desorption is influenced by the presence of steps. Below 525°K, the NO scattering results are quite different from those of CO and can not be simulated with the simple models that were tried. The data can be used, however, to rule out several models of surface interactions. NO does not dissociate detectably between 400 K ~1200 K under our experimental conditions. The sticking coefficient decreases with increasing coverage.},
doi = {},
url = {https://www.osti.gov/biblio/1108709}, journal = {Surface Science},
issn = {0039-6028},
number = 2-3,
volume = 107,
place = {United States},
year = {Sat Nov 01 00:00:00 EST 1980},
month = {Sat Nov 01 00:00:00 EST 1980}
}