Europhys. Lett.
Volume 69, Number 1, January 2005
Page(s) 61 - 67
Section Electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics
Published online 08 December 2004
Europhys. Lett., 69 (1), pp. 61-67 (2005)
DOI: 10.1209/epl/i2004-10301-8

Resonant effects in optical second-harmonic generation from alkali covered $\chem{Si(111)}$ $\mth{7\times7}$

V. G. Bordo1, G. Marowsky2, J. Zhang3 and H.-G. Rubahn4

1  Natural Sciences Center, A. M. Prokhorov General Physics Institute Russian Academy of Sciences - 119991 Moscow, Russia
2  Laser Laboratorium Göttingen e.V. - Hans-Adolf-Krebs-Weg 1 D-37077 Göttingen, Germany
3  Optical Engineering Department, Xian Institute of Technology - Xian, PRC
4  Fysisk Institut, Syddansk Universitet - DK-5230 Odense M, Denmark

received 26 May 2004; accepted in final form 26 October 2004
published online 8 December 2004

Polarized second-harmonic generation (SHG) coverage dependencies for alkali ( $\chem{Na, Li}$) adsorption on $\chem{Si(111)}$ $7\times7$ both at room and at low temperatures are obtained for fundamental wavelengths of 497 $\un{nm}$, 570 $\un{nm}$ and 1067 $\un{nm}$, showing characteristic and reproducible non-monotonic changes of SHG efficiency. At submonolayer coverage the SHG intensities are qualitatively different for visible vs. near-resonant IR radiation. In the coverage regime $\theta < 1/3$, low-symmetry $\chem{Na}$- $\chem{Si}$ bonds, resulting from a $\chem{Na}$-induced surface reconstruction, are formed, which are resonant with 1067 $\un{nm}$ radiation. By comparing parallelly and perpendicularly polarized coverage dependencies, we deduce that the resonant contribution in the parallel configuration is due to the $\chi^{(2)}_{zzz}$-component.

42.65.-k - Nonlinear optics.
78.20.-e - Optical properties of bulk materials and thin films.
78.66.-w - Optical properties of specific thin films.

© EDP Sciences 2005