| Autor: |
White, M. G., Beuhler, R. J. |
| Předmět: |
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| Zdroj: |
Journal of Chemical Physics; 2/1/2004, Vol. 120 Issue 5, p2445-2455, 11p, 1 Diagram, 2 Charts, 5 Graphs |
| Abstrakt: |
Rotationally resolved, velocity distributions for desorbed O[sub 2] molecules formed by O-atom recombination on the surface of a polycrystalline Ag surface are reported. Surface O atoms are generated by oxygen permeation through a 0.25-mm-thick Ag foil heated to 1020 K. Desorbing O[sub 2] molecules are probed by (2+1) resonant multiphoton ionization via the C [sup 3]Π[sub g] (3sσ), v[sup ′]=2←←X [sup 3]Σ[sub g][sup -], v[sup ″]=0 transition and time-of-flight mass spectrometry. Measured velocity distributions are near Maxwell–Boltzmann and yield average translational energies which are significantly lower than the surface temperature (/2k[sub B]∼515 K) and essentially independent of rotational excitation. Comparison of the observed C–X (2,0) resonantly enhanced multiphoton ionization spectrum with spectral simulations suggests that the v[sup ″]=0 rotational state distribution is more consistent with the surface temperature, but spectral congestion and apparent intensity perturbations prevent a more quantitative analysis. The calculated, sticking curves show a small barrier energy barrier (∼10 meV) beyond which sticking decreases. These observations are consistent with low energy desorption and adsorption pathways involving a weakly bound molecular O[sub 2] precursor. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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