Volume 79, Number 5, September 2007
Article Number 57002
Number of page(s) 5
Section Condensed Matter: Electronic Structure, Electrical, Magnetic and Optical Properties
Published online 30 July 2007
EPL, 79 (2007) 57002
DOI: 10.1209/0295-5075/79/57002

Optical gap between dangling-bond states of a single-domain diamond C(111)- $\mth{2 \times 1}$ by reflectance anisotropy spectroscopy

G. Bussetti1, C. Goletti1, P. Chiaradia1 and T. Derry2

1  Dipartimento di Fisica and CNISM, Università di Roma "Tor Vergata" - Roma, Italy
2  School of Physics and Centre of Excellence in Strong Materials, University of the Witwatersrand - Johannesburg, Wits 2050, South Africa

received 19 April 2007; accepted in final form 6 July 2007; published September 2007
published online 30 July 2007

The optical gap between dangling-bond states has been measured on a single-domain diamond C(111)-$2\times 1$ surface. The experimental result is 1.47 eV. Such a large surface gap (even larger if excitonic effects are considered) so far has not been obtained by state-of-the-art band calculations and its physical origin is still not elucidated. The experimental result suggests a strong electron-phonon interaction in this surface. The renormalization of the bare electronic transition energy by electron-phonon interaction provides a clue to solve the apparent disagreement between theory and experiment.

78.68.+m - Optical properties of surfaces.
73.20.At - Surface states, band structure, electron density of states.
68.35.Bs - Structure of clean surfaces (reconstruction).

© Europhysics Letters Association 2007