Six years passed by since the NATO ASI on "Liquid and Amorphous Metals" was held in Zwiesel, Germany, in September 1979. The present one is the second NATO School devoted to research on disordered condensed matter, mainly liquid and amorphous metals. This time the title contains the word "materials" to explicitely include those aspects of the glassy state of insulators either shared with metallic glasses - e.g. the glass tran sition - or on the border line with metallic systems - e.g. the metal non-metal transition. The long period which purposely elapsed between the two Institutes indi cates...

VI The idea to hold such a meeting in Germany for the first time was due to Prof. H. Pelzl. Its realization was greatly supported by financial help of the Stiftung Volkswagenwerk and the Deutsche Physikalische Gesellschaft, which is gratefully acknowledged. The Editors VII Contents 1. Basic Principles Photoacoustic Effect in Condensed Matter - Historical Development E. LUscher 1 Opto-Acoustic Spectroscopy - A Tool for the Study of Optical Spectra of very Transparent Materials 21 C. K. N. Patel Thermodynamic r ode 1 s of the Photoacousti c Effect P. Korpiun 40 Frequency Dependent Photoacous...