| Autor: |
Wang Y; Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131, USA., Nieman R; Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131, USA., Minton TK; Ann and H. J. Smead Department of Aerospace Engineering Sciences, University of Colorado, Boulder, Colorado 80303, USA., Guo H; Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131, USA. |
| Jazyk: |
angličtina |
| Zdroj: |
The Journal of chemical physics [J Chem Phys] 2021 Feb 21; Vol. 154 (7), pp. 074708. |
| DOI: |
10.1063/5.0042298 |
| Abstrakt: |
To gain insight into the nitrogen-related gas-surface reaction dynamics on carbon-based thermal protection systems of hypersonic vehicles, we have investigated the adsorption, diffusion, and reactions of atomic nitrogen, N( 4 S), on the (0001) face of graphite using periodic density functional theory with a dispersion corrected functional. The atomic nitrogen is found to bind with pristine graphite at a bridge site, with a barrier of 0.88 eV for diffusing to an adjacent bridge site. Its adsorption energy at defect sites is significantly higher, while that between graphene layers is lower. The formation of N 2 via Langmuir-Hinshelwood (LH) and Eley-Rideal (ER) mechanisms was also investigated. In the LH pathway, the recombinative desorption of N 2 proceeds via a transition state with a relatively low barrier (0.53 eV). In addition, there is a metastable surface species, which is capable of trapping the nascent N 2 at low surface temperatures as a result of the large energy disposal into the N-N vibration. The desorbed N 2 is highly excited in both of its translational and vibrational degrees of freedom. The ER reaction is direct and fast, and it also leads to translationally and internally excited N 2 . Finally, the formation of CN from a defect site is calculated to be endoergic by 2.75 eV. These results are used to rationalize the results of recent molecular beam experiments. |
| Databáze: |
MEDLINE |
| Externí odkaz: |
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