Surface Vibrational Spectroscopy of Adsorbates on Metals, Semiconductors and Liquid/Solid Interfaces by Sum-Frequency Generation

Surface vibrational spectroscopy is of central importance for surface studies. Most of the existing spectroscopic techniques, unfortunately, have serious limitations. Recently, we have developed a new versatile surface spectroscopic tool, infrared-visible sum-frequency generation (SFG)1, that has a number of clear advantages over the existing techniques. Like optical second harmonic generation, SFG is highly surface-specific, and is applicable to all interfaces accessible by light. With the help of ultrashort pump pulses, it has the potential of being able to monitor in-situ surface dynamics, surface reactions, and intermediate transient species with picosecond time resolution.