9710140 Nelson The aim of this proposal is to achieve an improved fundamental understanding of the dynamical and structural evolution of amorphous and partially disordered materials. Density dynamics of super cooled liquids in the picosecond through millisecond range will be examined, together with the mode-coupling theoretical predictions of supercooled liquid behavior. Linear and (primarily) nonlinear lattice dynamics in crystals near structural phase transitions will be studied to elucidate anharmonic crystalline potential energy surfaces that dictate phase transition mechanisms as well as the dynamics of phase transitions under the influence of short laser pulses. Measurements will also be conducted on thin film structures using laser generated acoustic waves to carry out a systematic study of adhesion, and to develop a new kind of photoacoustic imaging of patterned films and film-substrate assemblies such as those used in microelectronics. %%% An understanding of condensed materials such as glass forming liquids and sol-gel glasses with viscous liquid guests are of tremendous importance to industries involved with the advancement of various technologies dependent on both bulk and thin film materials applications. For example, this project will develop new techniques that will allow for the first-time a thorough characterization of adhesion mechanics in highly spatially resolved film substrate structures, the study of semiconductor transitions under the influence of short laser pulses, and density dynamics in glass forming liquids that will allow more complete testing of theoretical predictions and additional guidance for theoretical development.
