Adsorption of CO Molecules on Si(001) at Room Temperature
- Authors
- Seo, Eonmi; Eom, Daejin; Kim, Hanchul; Koo, Ja-Yong
- Issue Date
- Aug-2014
- Publisher
- AMER CHEMICAL SOC
- Citation
- JOURNAL OF PHYSICAL CHEMISTRY C, v.118, no.37, pp 21463 - 21468
- Pages
- 6
- Journal Title
- JOURNAL OF PHYSICAL CHEMISTRY C
- Volume
- 118
- Number
- 37
- Start Page
- 21463
- End Page
- 21468
- URI
- https://scholarworks.sookmyung.ac.kr/handle/2020.sw.sookmyung/10797
- DOI
- 10.1021/jp505971w
- ISSN
- 1932-7447
1932-7455
- Abstract
- Initial adsorption of CO molecules on Si(001) is investigated by using room-temperature (RT) scanning tunneling microscopy (STM) and density functional theory calculations. Theoretical calculations show that only one adsorption configuration of terminal-bound CO (T-CO) is stable and that the bridge-bound CO is unstable. All the abundantly observed STM features due to CO adsorption can be identified as differently configured T-COs. The initial sticking probability of CO molecules on Si(001) at RT is estimated to be as small as similar to 1 X 10(-4) monolayer/ Langmuir, which is significantly increased at high-temperature adsorption experiments implying a finite activation barrier for adsorption. Thermal annealing at 900 K for 5 min results in the dissociation of the adsorbed CO molecules with the probability of 60-70% instead of desorption, indicating both a strong chemisorption state and an activated dissociation process. The unique adsorption state with a large binding energy, a tiny sticking probability, and a finite adsorption barrier is in stark contrast with the previous low-temperature (below 100 K) observations of a weak binding, a high sticking probability, and a barrierless adsorption. We speculate that the low-temperature results might be a signature of a physisorption state in the condensed phase.
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