Abstract
Advances in ultrafast laser technologies encourage surface scientists to explore electron and nuclear dynamics at surfaces. Major spectroscopic means are time-resolved nonlinear laser spectroscopy including second harmonic generation (SHG), sum frequency generation (SFG), and two-photon photoemission (2PPE). After introducing fundamental aspects of the nonlinear spectroscopy briefly, this paper describes some recent applications of the nonlinear spectroscopy to ultrafast dynamics at surfaces. Examples include: (1) SFG with tunable infrared pulsed lasers is used for exploring how the vibrational modes of adsorbate couple to bulk phonons when a metal surface is rapidly heated by an ultrafast laser pulse. (2) A vibrational motion of adsorbate on a metal surface is coherently excited by an ultrafast laser pulse and the dephasing of the vibrational mode is probed by time-resolved SHG. (3) Ultrafast electron decay and electron hydration dynamics are explored by 2PPE.
