Thursday, December 18, 2008, 10:00 am — Bldg 735 (CFN) Conference Room B
The recent discovery of a fundamentally new sound-like plasmon on a bare metal surface of beryllium may introduce a new research direction in the area of plasmonics [1]. While conventional surface plasmons are optical modes and have a finite excitation energy of a few eV, the novel acoustic surface plasmon (ASP) mode can be excited with very low energies of a few meV. This allows, in principle, for a coupling with visible light for signal processing and advanced microscopies as well as new catalysts on metallic surfaces. I will present results showing the acoustic character of the new plasmon as measured with electron energy loss spectroscopy on the compact surfaces of Be, Cu, and Au, and also the influence of vicinal surface band structure on the ASP modes as seen for Au(788). Furthermore, I will show that the novel ASP mode is a general phenomenon on metal surfaces that support a partially occupied surface state within a wide bulk energy gap. The ASP mode is caused by the non-local screening of the surface electrons due to bulk electron plural.
[1] B. Diaconescu, et al., Nature 448, 57 (2007).
This work was supported in parts by the NSF under Grant No. DMR-0134933 and DMR-0753467.
Hosted by: Peter Sutter
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