Recent progress in analytical SHG spectroscopy

The progress of laser technology has brought extensive applications of nonlinear optical (NLO) spectroscopy to analytical fields. Especially, optical second harmonic generation (SHG), which is one of the most popular NLO phenomena, has been successfully applied to the study of interfaces (surfaces). Several fine reviews on surface SHG spectroscopies have appeared recently. The present article will concentrate on some new applications of SHG: second harmonic microscopy (SHM) for microstructural characterization, SHG interferometry for the determination of absolute molecular orientation, surface analysis of microstructures, and some molecular interactions at the interfaces.