Abstract
Infrared-visible sum-frequency generation (SFG) spectroscopy is a modern surface vibrational spectroscopy that uses non-linear optical processes with ultra-short laser pulses. An advantage of the SFG spectroscopy is its ultra-short time resolution, which enables the observation of vibrational spectra on the picosecond time scale. Irradiation with near-infrared (NIR) pulses causes a temporary temperature jump at metal surfaces, with the surface temperature jumping by several hundred degrees, before recovering in the time of sub-nanosecond. The surface species is thermally excited by the irradiation and sometimes changes its chemical structure, without desorbing from the surface. This technique is regarded as a powerful tool for the identification of unstable states of surface molecules involved in thermal reactions. This article describes the dynamic behavior of surface molecules under the irradiation with NIR pulse for the CO/Ni(111), cyclohexane/Ni(111), and D2O/CO/Pt(111) systems.
