| Autor: |
Tait, Steven L., Dohnálek, Zdenek, Campbell, Charles T., Kay, Bruce D. |
| Předmět: |
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| Zdroj: |
Journal of Chemical Physics; 4/22/2005, Vol. 122 Issue 16, p164707, 9p, 10 Graphs |
| Abstrakt: |
High-quality temperature-programmed desorption (TPD) measurements of n-butane from MgO(100) have been made for a large number of initial butane coverages (0–3.70 ML, ML–monolayers) and a wide range of heating ramp rates (0.3–10 K/s). We present a TPD analysis technique which allows the coverage-dependent desorption energy to be accurately determined by mathematical inversion of a TPD spectrum, assuming only that the preexponential factor (prefactor) is coverage independent. A variational method is used to determine the prefactor that minimizes the difference between a set of simulated TPD spectra and corresponding experimental data. The best fit for butane desorption from MgO is obtained with a prefactor of 1015.7±1.6 s-1. The desorption energy is 34.9±3.4 kJ/mol at 0.5-ML coverage, and varies with coverage approximately as Ed(θ)=34.5+0.566θ+8.37 exp(-θ/0.101). Simulations based on these results can accurately reproduce TPD experiments for submonolayer initial coverages over a wide range of heating ramp rates (0.3–10 K/s). Advantages and limitations of this method are discussed. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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