Abstract

Second-order nonlinear optical processes are forbidden in bulks with inversion symmetry, but necessarily allowed at surfaces and interfaces. This intrinsic surface specificity has rendered second harmonic generations (SHG) and sum frequency generation (SFG) exceptionally useful as surface probes. SFG in particular has been developed into an extremely powerful surface spectroscopic tool. It is applicable to all interfaces accessible by light and therefore has provided new research opportunities in many areas of surface science.

© 1998 Optical Society of America