Abstract

The observation and analysis of surface second harmonic generation (SHG) phenomena by Shen and coworkers (1) suggest that SHG spectroscopy is an effective interface - specific approach to detecting electronic spectra of surface and interfacial species. Since SHG is only possible in regions lacking inversion symmetry, the interface between two such materials will be the only source of an SHG signal. If a dye laser beam at frequency ω is focused upon this interface and the harmonic at 2ω is monitored as the laser is scanned in frequency, then an electronic spectrum of interfacial species can be generated because of the great enhancement of the second order susceptibility, χ⁽²⁾, when 2ω concides with an electronic transition. In this way, spectra of species at solid-solid, solid-liquid, solid-vapor, liquid-liquid and liquid-vapor interfaces can be considered.

© 1985 Optical Society of America