Walter E. Bron – författare

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 resultant research field has most recently blossomed with the development of ever more sophisticated experimental and theoretical methods which can be applied to it. In fact, the field is moving so rapidly that new members of the research community have difficulties in keeping up to date. This NATO Advanced Study Institute (ASI) was organized with the objective of overcoming the information barrier between those expert in the field and those who are new to it. Thus it was decided to (i) organize a set of tutorially based lectures covering most of the important facets in the field, and (ii) to produce an Institute proceedings which would serve both as the first general textbook, as well as a valuable reference book, for this field of knowledge.

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 resultant research field has most recently blossomed with the development of ever more sophisticated experimental and theoretical methods which can be applied to it. In fact, the field is moving so rapidly that new members of the research community have difficulties in keeping up to date. This NATO Advanced Study Institute (ASI) was organized with the objective of overcoming the information barrier between those expert in the field and those who are new to it. Thus it was decided to (i) organize a set of tutorially based lectures covering most of the important facets in the field, and (ii) to produce an Institute proceedings which would serve both as the first general textbook, as well as a valuable reference book, for this field of knowledge.

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 on the dynamics of such excitations, are carried out in the bulk, at surfaces, in thin films, and in quantum wells. The dynamical steps which the excitations usually undergo include photo-excitation, local thermalization, particle-particle interaction, particle phonon interactions and eventual return to true thermal equilibrium. This ASI was organized to benefit particularly advanced graduate students, specifically, those near the end of their Ph.D. thesis projects, and also for postdoctoral scholars already active in the field. The overall organizational goal was centered around a set oftutorially based lectures intermingled with full scale discussion periods of equal time and importance as the lectures. The general discussion periods were designed to offer to the participants ample time to ask detailed questions and to make comments and contributions of their own. In order to complete the involvement of the participants a full length poster session was also held. A representative set of abstracts of these posters appear as an Appendix to the lectures.