Abstract

The azimuthal dependence of optical second harmonic generation at the surface of centrosymmetric crystals is a sensitive tool for the investigation of geometrical order and structure of these surfaces^1-4. The technique consists of irradiating the sample under study by pulsed laser light with a fixed polarization and detecting the second harmonic radiation in reflection, also at fixed polarization. The azimuthal dependence of the nonlinear process is then obtained by rotating the sample about the surface normal. A detailed description of the experimental set-up can be found in Ref.⁴. This technique provides a sensitive way of probing the surface dipolar susceptibility, in other words the degree of freedom of the electronic motion in the surface layer. Its advantage is that it can be used as well in ultra-high vacuum with clean and defined surfaces as in ambient atmosphere. Hence, it is possible to relate observations under wel1-controlled conditions to identical experiments in a realistic environment.

© 1989 Optical Society of America