Phonons are always present in the solid state even at an absolute temperature of 0 K where zero point vibrations still abound. Moreover, phonons interact with all other excitations of the solid state and, thereby, influence most of its properties. Historically experimental information on phonon transport came from measurements of thermal conductivity. Over the past two decades much more, and much more detailed, information on phonon transport and on many of the inherent phonon interaction processes have come to light from experiments which use nonequilibrium phonons to study their dynamics....

The Advanced Study Institute (AS ) considered a number offacets of the very rapidly advancing field of theoretical and experimental aspects of ultrashort processes in condensed matter. Common threads exist between a series of example cases. One major subgroup of topics involves the ultrashort dynamics of excitations of various "particles" produced through the interactions of condensed matter with ultrashort duration laser light. Examples ofthe excitations include electronic and hole carriers, electron-hole plasma, phonons, vibrons and rotons, two phonon states, and excitons. Experimentation...