Abstract
Two kinds of surface phonons, macroscopic and microscopic, are excited at solid surfaces. Macroscopic surface phonons, such as Rayleigh waves and Fuchs-Kliewer waves, have been long known experimentally and theoretically, and have been applied to electric devices. On the other hand, microscopic surface phonons, whose vibrational amplitude is localized to a few atomic layers near the surface, have been measured only during the last few years. Large progress has recently been made in this field, and is reviewed.
