Electron Energy Loss Spectroscopy of CO, O2, and H2 Adsorbed on Au-Ni(111)
Event details
| Date | 17.03.2016 |
| Hour | 16:30 › 17:30 |
| Speaker |
Dr. Christopher Leon Postdoctoral Fellow Ceyer Group Surface Science at MIT - Department of Chemistry |
| Location | |
| Category | Conferences - Seminars |
The adsorptive behavior of CO, O2, and H2 on Au‑Ni(111) surface alloys is investigated as a function of surface Au coverage, up to 0.79 ML Au. Vibrational spectra (obtained via high-resolution electron energy loss spectroscopy) of Au‑Ni(111) subject to saturation exposures of CO, O2 and H2 at 77 K reveal new adsorption states identifiable by the internal vibrational stretch frequency of molecularly adsorbed species. These include: CO adsorption at Ni-bridge (1960 cm‑1), Ni-atop (2110 cm‑1), and Au‑atop (2160 cm‑1); and O2 adsorption at bridge (856 cm‑1) and fcc/hcp hollows (743, 957 cm‑1) with sensitivity to subsurface atoms. There is also evidence for H2 dissociative adsorption leading to subsurface interstitial site population (750, 820 cm-1). An analysis of the adsorption site occupation fractions leads to self-consistent structural models of the Au-Ni(111) surface alloy. The stability of these chemical species normally absent on Ni(111) can be explained by considering changes to the d-band center due to alloying, and structural effects induced by an accompanying complex surface reconstruction.
Practical information
- Informed public
- Free
- This event is internal
Organizer
- Prof. Ulrich Lorenz